WorldWideScience

Sample records for maillard reaction mixtures

  1. Identification of hydrogen peroxide as a major cytotoxic component in Maillard reaction mixtures and coffee.

    Science.gov (United States)

    Hegele, Jörg; Münch, Gerald; Pischetsrieder, Monika

    2009-06-01

    The cytotoxic activity of Maillard reaction products and coffee was studied using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay and the neutral red uptake (NRU) assay. Equimolar mixtures of sugars and lysine were heated at 120 degrees C and used to stimulate bovine aorta endothelial cells for 24 h. The cytotoxic activity increased with increase in educt concentration and heating time. Mixtures containing ribose were most active, followed by lactose and glucose. Hydrogen peroxide, which was present in the Maillard mixtures in concentrations between 7 and 87 microM, was identified as one of their major cytotoxic components. H2O2-concentrations increased further up to 130 microM under cell culture conditions. Filter coffee, espresso, and green coffee extract reduced cell viability significantly to 10, 19, and 83% of PBS-treated control. The effect was largely attenuated by the addition of catalase. Nil, 33, and 41 microM H2O2 was measured in green coffee extract, filter coffee, and espresso, respectively, increasing to 13, 369, and 333 microM during cell culture conditions. No additional H2O2 formation was detected when coffee was incubated for up to 5 h without further treatment. In conclusion, hydrogen peroxide is a major product in Maillard mixtures and coffee inducing cell death in vitro.

  2. Dicarbonyl Intermediates in the Maillard Reaction

    National Research Council Canada - National Science Library

    THORNALLEY, PAUL J

    2005-01-01

    A bstract : The complexity of the Maillard reaction arises partly from multiple fragmentation reactions of the sugar moiety, constituting branch points in the reaction progress and establishing many parallel reaction pathways...

  3. Effect of heating on Maillard reactions in milk.

    NARCIS (Netherlands)

    Boekel, van M.A.J.S.

    1998-01-01

    Heated milk is subject to the Maillard reaction; lactose and lysine residues in milk proteins (mainly casein) are the reactants. An overview is given of the early, advanced and final stages of the Maillard reaction as it occurs in milk. The early Maillard reaction is confined to the formation of the

  4. Maillard reaction products in pet foods

    NARCIS (Netherlands)

    Rooijen, van C.

    2015-01-01

    Pet dogs and cats around the world are commonly fed processed commercial foods throughout their lives. Often heat treatments are used during the processing of these foods to improve nutrient digestibility, shelf life, and food safety. Processing is known to induce the Maillard reaction, in which a

  5. Maillard reaction products in pet foods

    NARCIS (Netherlands)

    Rooijen, van C.

    2015-01-01

    Pet dogs and cats around the world are commonly fed processed commercial foods throughout their lives. Often heat treatments are used during the processing of these foods to improve nutrient digestibility, shelf life, and food safety. Processing is known to induce the Maillard reaction, in which a r

  6. Maillard reaction products in pet foods

    OpenAIRE

    Rooijen, van, J.

    2015-01-01

    Pet dogs and cats around the world are commonly fed processed commercial foods throughout their lives. Often heat treatments are used during the processing of these foods to improve nutrient digestibility, shelf life, and food safety. Processing is known to induce the Maillard reaction, in which a reducing sugar binds to a free reactive amino group of an amino acid. In intact proteins, the ε-amino group of lysine is the most abundant free amino group. The reaction reduces the bioavail...

  7. Quantitation of Maillard reaction products in commercially available pet foods

    NARCIS (Netherlands)

    Rooijen, van C.; Bosch, G.; Poel, van der A.F.B.; Wierenga, P.A.; Alexander, L.; Hendriks, W.H.

    2014-01-01

    During processing of pet food, the Maillard reaction occurs, which reduces the bioavailability of essential amino acids such as lysine and results in the formation of advanced Maillard reaction products (MRPs). The aim of this study was to quantitate MRPs (fructoselysine (FL), carboxymethyllysine

  8. Studies on Absorption and Elimination of Dietary Maillard Reaction Products

    National Research Council Canada - National Science Library

    FÖRSTER, ANKE; KÜHNE, YVONNE; HENLE, T.OMAS

    2005-01-01

    A bstract : A nine‐day dietary study involving 18 healthy volunteers was performed in order to investigate the influence of nutrition on the urinary excretion of the Maillard reaction products (MRPs...

  9. Maillard reaction products as antimicrobial components for packaging films.

    Science.gov (United States)

    Hauser, Carolin; Müller, Ulla; Sauer, Tanja; Augner, Kerstin; Pischetsrieder, Monika

    2014-02-15

    Active packaging foils with incorporated antimicrobial agents release the active ingredient during food storage. Maillard reaction products (MRPs) show antimicrobial activity that is at least partially mediated by H2O2. De novo generation of H2O2 by an MRP fraction, extracted from a ribose/lysine Maillard reaction mixture by 85% ethanol, was monitored at three concentrations (1.6, 16.1, and 32.3g/L) and three temperatures (4, 25, and 37 °C) between 0 and 96 h, reaching a maximum of 335 μM H2O2 (32.3g/L, 37 °C, 96 h). The active MRP fraction (16.1g/L) completely inhibited the growth of Escherichia coli for 24h and was therefore incorporated in a polyvinyl acetate-based lacquer and dispersed onto a low-density polyethylene film. The coated film generated about 100 μM H2O2 and resulted in a log-reduction of >5 log-cycles against E. coli. Thus, MRPs can be considered as active ingredients for antimicrobial packaging materials.

  10. Effective Components of Chinese Herbal Compound Decoction and Maillard Reaction

    Institute of Scientific and Technical Information of China (English)

    曹治云; 陈旭征; 张恩达; 杜建

    2009-01-01

    This paper intends to explore the color changes considered to be Maillard reaction during the process of Chinese herbal medicine.The Maillard reaction products(MRPs) are often in substantial proportions of Chinese herbal compound decoctions but their effects are often neglected.By considering the effects of MRPs in studies of effective components on Chinese herbal compounds,a new perspective is established in future researches of Chinese herbal compound decoctions.

  11. Historical perspective of the Maillard reaction in food science.

    Science.gov (United States)

    Finot, Paul-André

    2005-06-01

    Maillard's paper of 1912 describing the reaction between amino acids and sugars is both innovative and visionary. It provides original and still-valuable data on the chemistry of a new reaction and foresees its involvement in many scientific and biological domains, even in human pathology. This paper was ignored by the scientific community until 1941. In 1948 the Maillard reaction was definitely recognized as being responsible for the browning and loss of nutritive value of heated milk powders. There was then a continuous increase in papers on the chemistry of this complex reaction to identify its various pathways: in food science, to evaluate the influence of reaction parameters (pH, T degrees , time, sugar reactivity, concentration of the reagents, water activity, glass transition temperature) on the evolution of the reaction and on changes in food quality; in nutrition, to quantify the loss of bioavailability of essential amino acids; on the metabolism of the reaction products and on the physiological effects of the ingested Maillard reaction products. The significant scientific advances and the key persons and pioneers who contributed much to the understanding of the Maillard reaction are presented. The food industry is directly concerned with the occurrence of this reaction in processed foods and contributed significantly by its own research to understanding the phenomena and to optimizing the processes and conditions of food preparation in order to preserve the nutritional, safety, and organoleptic qualities of foods.

  12. Melanoidins extinction coefficient in the glucose/glycine Maillard reaction

    NARCIS (Netherlands)

    Martins, S.I.F.S.; Boekel, van M.A.J.S.

    2003-01-01

    Melanoidins (brown, nitrogenous polymers and co-polymers) are the final products of the Maillard reaction. The glucose/glycine melanoidins extinction coefficient was determined using C-14-labelled glucose at three different reaction conditions. The absorbance was measured at different wavelengths (4

  13. Preparation of natural isovaleraldehyde by the Maillard reaction

    Institute of Scientific and Technical Information of China (English)

    Hong Yu Tian; Jie Zhang; Bao Guo Sun; Ming Quan Huang; Jian Rong Li; Xiao Xiang Han

    2007-01-01

    Isovaleraldehyde possesses malty, fruity, cocoa-like odor and is widely used in fruit, chocolate, coffee flavors. The preparation of natural isovaleraldehyde by the Maillard model reaction was studied in this paper. The effects of the ratio of D-glucose/L-leucine,reaction temperature and pH value on the yield of isovaleraldehyde were explored. The optimum conditions were as follows:n(D-glucose):n(L-leucine) = 4, temperature 150 ℃, reaction time 3 h, pH 5. The highest yield of isovaleraldehyde obtained was about 32%.

  14. One-step simultaneous differential scanning calorimetry-FTIR microspectroscopy to quickly detect continuous pathways in the solid-state glucose/asparagine Maillard reaction.

    Science.gov (United States)

    Hwang, Deng-Fwu; Hsieh, Tzu-Feng; Lin, Shan-Yang

    2013-01-01

    The stepwise reaction pathway of the solid-state Maillard reaction between glucose (Glc) and asparagine (Asn) was investigated using simultaneous differential scanning calorimetry (DSC)-FTIR microspectroscopy. The color change and FTIR spectra of Glc-Asn physical mixtures (molar ratio = 1:1) preheated to different temperatures followed by cooling were also examined. The successive reaction products such as Schiff base intermediate, Amadori product, and decarboxylated Amadori product in the solid-state Glc-Asn Maillard reaction were first simultaneously evidenced by this unique DSC-FTIR microspectroscopy. The color changed from white to yellow-brown to dark brown, and appearance of new IR peaks confirmed the formation of Maillard reaction products. The present study clearly indicates that this unique DSC-FTIR technique not only accelerates but also detects precursors and products of the Maillard reaction in real time.

  15. New tools in modulating Maillard reaction from model systems to food

    NARCIS (Netherlands)

    Troise, A.D.

    2015-01-01

    New tools in modulating Maillard reaction from model systems to food
    The Maillard reaction (MR) supervises the final quality of foods and occupies a prominent place in food science. The first stable compounds, the Amadori rearrangement products (

  16. The effect of steam pelleting of a dry dog food on the Maillard reaction

    NARCIS (Netherlands)

    Rooijen, van C.; Bosch, G.; Wierenga, P.A.; Hendriks, W.H.; Poel, van der A.F.B.

    2014-01-01

    During processing of pet foods, the Maillard reaction (MR) can occur, which reduces the bioavailability of essential amino acids like lysine and results in the formation of advanced Maillard reaction products (MRPs). This study examined the effect of conditioning temperature (65 and 90 °C) and die

  17. The Maillard reaction and pet food processing: effects on nutritive value and pet health

    NARCIS (Netherlands)

    Rooijen, van C.; Bosch, G.; Poel, van der A.F.B.; Wierenga, P.A.; Alexander, L.; Hendriks, W.H.

    2013-01-01

    The Maillard reaction, which can occur during heat processing of pet foods or ingredients, is known to reduce the bioavailability of essential amino acids such as lysine due to the formation of early and advanced Maillard reaction products (MRP) that are unavailable for utilisation by the body.

  18. The effect of steam pelleting of a dry dog food on the Maillard reaction

    NARCIS (Netherlands)

    Rooijen, van C.; Bosch, G.; Wierenga, P.A.; Hendriks, W.H.; Poel, van der A.F.B.

    2014-01-01

    During processing of pet foods, the Maillard reaction (MR) can occur, which reduces the bioavailability of essential amino acids like lysine and results in the formation of advanced Maillard reaction products (MRPs). This study examined the effect of conditioning temperature (65 and 90 °C) and die h

  19. New tools in modulating Maillard reaction from model systems to food

    NARCIS (Netherlands)

    Troise, A.D.

    2015-01-01

    New tools in modulating Maillard reaction from model systems to food
    The Maillard reaction (MR) supervises the final quality of foods and occupies a prominent place in food science. The first stable compounds, the Amadori rearrangement products (

  20. The Maillard reaction and pet food processing: effects on nutritive value and pet health

    NARCIS (Netherlands)

    Rooijen, van C.; Bosch, G.; Poel, van der A.F.B.; Wierenga, P.A.; Alexander, L.; Hendriks, W.H.

    2013-01-01

    The Maillard reaction, which can occur during heat processing of pet foods or ingredients, is known to reduce the bioavailability of essential amino acids such as lysine due to the formation of early and advanced Maillard reaction products (MRP) that are unavailable for utilisation by the body. Dete

  1. The dual effects of Maillard reaction and enzymatic hydrolysis on the antioxidant activity of milk proteins.

    Science.gov (United States)

    Oh, N S; Lee, H A; Lee, J Y; Joung, J Y; Lee, K B; Kim, Y; Lee, K W; Kim, S H

    2013-08-01

    The objective of this study was to determine the enhanced effects on the biological characteristics and antioxidant activity of milk proteins by the combination of the Maillard reaction and enzymatic hydrolysis. Maillard reaction products were obtained from milk protein preparations, such as whey protein concentrates and sodium caseinate with lactose, by heating at 55°C for 7 d in sodium phosphate buffer (pH 7.4). The Maillard reaction products, along with untreated milk proteins as controls, were hydrolyzed for 0 to 3h with commercial proteases Alcalase, Neutrase, Protamex, and Flavorzyme (Novozymes, Bagsværd, Denmark). The antioxidant activity of hydrolyzed Maillard reaction products was determined by reaction with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, their 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, and the ability to reduce ferric ions. Further characteristics were evaluated by the o-phthaldialdehyde method and sodium dodecyl sulfate-PAGE. The degree of hydrolysis gradually increased in a time-dependent manner, with the Alcalase-treated Maillard reaction products being the most highly hydrolyzed. Radical scavenging activities and reducing ability of hydrolyzed Maillard reaction products increased with increasing hydrolysis time. The combined products of enzymatic hydrolysis and Maillard reaction showed significantly greater antioxidant activity than did hydrolysates or Maillard reaction products alone. The hydrolyzed Maillard reaction products generated by Alcalase showed significantly higher antioxidant activity when compared with the other protease products and the antioxidant activity was higher for the whey protein concentrate groups than for the sodium caseinate groups. These findings indicate that Maillard reaction products, coupled with enzymatic hydrolysis, could act as potential antioxidants in the pharmaceutical, food, and dairy industries.

  2. The Maillard reaction and food allergies: is there a link?

    Science.gov (United States)

    Toda, Masako; Heilmann, Monika; Ilchmann, Anne; Vieths, Stefan

    2014-01-01

    Food allergies are abnormal responses to a food triggered by the immune system. The majority of allergenic foods are often subjected to thermal processing before consumption. The Maillard reaction is a non-enzymatic reaction between reducing sugars and compounds with free amino groups such as amino acids and proteins, and takes place during thermal processing and storage of foods. Among many other effects the reaction leads to modification of proteins with various types of glycation structures such as Nε-(carboxymethyl-)lysine (CML), pentosidine, pyrraline and methylglyoxal-H1, which are collectively called advanced glycation end-products (AGEs). Notably, evidence has accumulated that some glycation structures of AGEs function as immune epitopes. Here we discuss the possible involvement of food allergen AGEs in the pathogenesis of food allergies.

  3. Isolation and identification of a novel aromatic amine mutagen produced by the Maillard reaction.

    Science.gov (United States)

    Nishigaki, Rena; Watanabe, Tetsushi; Kajimoto, Tetsuya; Tada, Atsuko; Takamura-Enya, Takeji; Enomoto, Shigeki; Nukaya, Haruo; Terao, Yoshiyasu; Muroyama, Atsushi; Ozeki, Minoru; Node, Manabu; Hasei, Tomohiro; Totsuka, Yukari; Wakabayashi, Keiji

    2009-09-01

    To clarify the formation of mutagens in the Maillard reaction of glucose and amino acids, 20 amino acids were separately incubated with glucose in the presence or absence of hydroxyl radicals produced by the Fenton reaction. After 1 week at 37 degrees C and pH 7.4, the reaction mixtures of glucose and tryptophan with and without the Fenton reagent showed mutagenicity toward Salmonella typhimurium YG1024 in the presence of a mammalian metabolic system (S9 mix). To identify mutagens in the reaction mixture, blue rayon-adsorbed material from a mixture of glucose, tryptophan, and the Fenton reagent was separated by column chromatography using various solid and mobile phases, and one mutagen, which accounted for 18% of the total mutagenicity of the reaction mixture, was isolated. The chemical structure of the mutagen was determined to be 5-amino-6-hydroxy-8H-benzo[6,7]azepino[5,4,3-de]quinolin-7-one (ABAQ) on the basis of ESI mass, high-resolution APCI mass, (1)H NMR, (13)C NMR, and IR spectral analyses and chemical synthesis of the mutagen. The novel aromatic amine showed high mutagenicity toward S. typhimurium TA98 and YG1024 with S9 mix, inducing 857 revertants of TA98 and 6007 revertants of YG1024/microg, respectively. The mutagenicity of ABAQ was comparable to that of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, which is a mutagenic and carcinogenic hetrocyclic amine in cooked meat and fish formed through the Maillard reaction at high temperature.

  4. In vivo formation of Maillard reaction free radicals in mouse skin

    National Research Council Canada - National Science Library

    Lloyd, R V; Fong, A J; Sayre, R M

    2001-01-01

    The Maillard browning reaction between carbohydrates and amines is part of an extensive series of reactions that is the basis for the brown color caused by the "sunless tanning" agent dihydroxyacetone...

  5. Food Protein-polysaccharide Conjugates Obtained via the Maillard Reaction: A Review.

    Science.gov (United States)

    de Oliveira, Fabíola Cristina; Coimbra, Jane Sélia Dos Reis; de Oliveira, Eduardo Basílio; Zuñiga, Abraham Damian Giraldo; Rojas, Edwin E Garcia

    2016-05-18

    The products formed by glycosylation of food proteins with carbohydrates via the Maillard reaction, also known as conjugates, are agents capable of changing and improving techno-functional characteristics of proteins. The Maillard reaction uses the covalent bond between a group of a reducing carbohydrates and an amino group of a protein. This reaction does not require additional chemicals as it occurs naturally under controlled conditions of temperature, time, pH, and moisture. Moreover, there is growing interest in modifying proteins for industrial food applications. This review analyses the current state of art of the Maillard reaction on food protein functionalities. It also discusses the influence of the Maillard reaction on the conditions and formulation of reagents that improve desirable techno-functional characteristics of food protein.

  6. Maillard Reactions of Ribose 5‐Phosphate and Amino Acids

    National Research Council Canada - National Science Library

    SANDWICK, ROGER; JOHANSON, MATTHEW; BREUER, ELIZABETH

    2005-01-01

    A bstract : An important metabolite in nucleotide synthesis, ribose 5‐phosphate (R5P) undergoes Maillard reactions at a rate significantly faster than most common sugars and sugar phosphates of its type...

  7. Contribution of crosslinking products in the flavour enhancer processing: the new concept of Maillard peptide in sensory characteristics of Maillard reaction systems.

    Science.gov (United States)

    Karangwa, Eric; Murekatete, Nicole; Habimana, Jean de Dieu; Masamba, Kingsley; Duhoranimana, Emmanuel; Muhoza, Bertrand; Zhang, Xiaoming

    2016-06-01

    In this study, the flavour-enhancing properties of the Maillard reaction products (MRPs) for different systems consisted of different peptides (sunflower, SFP; corn, CP and soyabean SP) with, xylose and cysteine were investigated. Maillard systems from peptides of sunflower, corn and soyabean with xylose and cysteine were designated as PXC, MCP and MSP, respectively. The Maillard systems were prepared at pH of 7.4 using temperature of 120C for 2 h. Results showed that all systems were significantly different in all sensory attributes. The highest scores for mouthfulness and continuity were observed for MCP with the lowest peptides distribution between 1000 and 5000 Da, known as Maillard peptide. This revealed that the MCP with the lowest Maillard peptide content had the strongest "Kokumi" effect compared to the other MRPsand demonstrated that "kokumi effect" of MRPs was contributed by not only the "Maillard peptide" defined by the molecular weight (1000-5000 Da). Results on sensory evaluation after fractionation of PXC followed by enzymatic hydrolysis showed no significant differences between PXC, P-PXC and their hydrolysates. This observation therefore confirmed that the presence of other contributors attributed to the "Kokumi" effect rather than the Maillard peptide. It can be deduced that the unhydrolyzed crosslinking products might have contributed to the "Kokumi" effect of MRPs. The structures of four probable crosslinking compounds were proposed and the findings have provided new insights in the sensory characteristics of xylose, cysteine and sunflower peptide MRPs.

  8. Triosidines: novel Maillard reaction products and cross-links from the reaction of triose sugars with lysine and arginine residues

    National Research Council Canada - National Science Library

    Tessier, Frederic J; Monnier, Vincent M; Sayre, Lawrence M; Kornfield, Julia A

    2003-01-01

    The role of the highly reactive triose sugars glyceraldehyde and glyceraldehyde-3-phosphate in protein cross-linking and other amino acid modifications during the Maillard reaction was investigated...

  9. Clay surface catalysis of formation of humic substances: potential role of maillard reactions

    Science.gov (United States)

    The mechanisms of the formation of humic substances are poorly understood, especially the condensation of amino acids and reducing sugars products (Maillard reaction) in soil environments. Clay minerals behave as Lewis and Brönsted acids and catalyze several reactions and likely to catalyze the Mai...

  10. The Maillard reaction and its control during food processing. The potential of emerging technologies.

    Science.gov (United States)

    Jaeger, H; Janositz, A; Knorr, D

    2010-06-01

    The Maillard reaction between reducing sugars and amino acids is a common reaction in foods which undergo thermal processing. Desired consequences like the formation of flavor and brown color of some cooked foods but also the destruction of essential amino acids and the production of anti-nutritive compounds require the consideration of the Maillard reaction and relevant mechanisms for its control. This paper aims to exemplify the recent advances in food processing with regard to the controllability of heat-induced changes in the food quality. Firstly, improved thermal technologies, such as ohmic heating, which allows direct heating of the product and overcoming the heat transfer limitations of conventional thermal processing are presented in terms of their applicability to reduce the thermal exposure during food preservation. Secondly, non-thermal technologies such as high hydrostatic pressure and pulsed electric fields and their ability to extend the shelf life of food products without the application of heat, thus also preserving the quality attributes of the food, will be discussed. Finally, an innovative method for the removal of Maillard reaction substrates in food raw materials by the application of pulsed electric field cell disintegration and extraction as well as enzymatic conversion is presented in order to demonstrate the potential of the combination of processes to control the occurrence of the Maillard reaction in food processing.

  11. Investigations on the Maillard reaction of dextrins during aging of Pilsner type beer.

    Science.gov (United States)

    Rakete, Stefan; Klaus, Alexander; Glomb, Marcus A

    2014-10-08

    Although Maillard reaction plays a pivotal role during preparation of food, only few investigations concerning the role of carbohydrate degradation in beer aging have been carried out. The formation of Maillard specific precursor structures and their follow-up products during degradation of low molecular carbohydrate dextrins in the presence of proline and lysine was studied in model incubations and in beer. Twenty-one α-dicarbonyl compounds were identified and quantitated as reactive intermediates. The oxidative formation of 3-deoxypentosone as the precursor of furfural from oligosaccharides was verified. N-Carboxymethylproline and N-formylproline were established as novel proline derived Maillard advanced glycation end products. Formation of N-carboxymethylproline and furfural responded considerably to the presence of oxygen and was positively correlated to aging of Pilsner type beer. The present study delivers an in-depth view on the mechanisms behind the formation of beer relevant aging parameters.

  12. Impact of Maillard Reaction on Immunoreactivity and Allergenicity of the Hazelnut Allergen Cor a 11

    NARCIS (Netherlands)

    Iwan, M.; Vissers, Y.M.; Fiedorowicz, E.; Kostyra, H.; Savelkoul, H.F.J.; Wichers, H.J.

    2011-01-01

    Few studies exist on the influence of processing methods on structural changes and allergenic potential of hazelnut proteins. This study focused on the effect of glycation (Maillard reaction) on the immunoreactivity and degranulation capacity of the purified hazelnut 7S globulin, Cor a 11. After hea

  13. A review of Maillard reaction in food and implications to kenetic modelling

    NARCIS (Netherlands)

    Martins, S.I.F.S.; Jongen, W.M.F.; Boekel, van M.A.J.S.

    2001-01-01

    This paper reviews some of the research designed to lead to an increased understanding of the chemistry of the Maillard reaction, based on recent developments, and its influence on food properties like colour, flavour and nutritional value. A critical analysis is given on how quality attributes

  14. A kinetic model for the glucose/glycine Maillard reaction pathways

    NARCIS (Netherlands)

    Martins, S.I.F.S.; Boekel, van M.A.J.S.

    2005-01-01

    A comprehensive kinetic model for the glucose/glycine Maillard reaction is proposed based on an approach called multiresponse kinetic modelling. Special attention was paid to reactants, intermediates and end products: -fructose, N-(1-deoxy--fructos-1-yl)-glycine (DFG), 1-deoxy-2,3-hexodiulose and

  15. Age-related accumulation of Maillard reaction products in human articular cartilage collagen

    NARCIS (Netherlands)

    Verzijl, N.; Groot, J. de; Oldehinkel, E.; Bank, R.A.; Thorpe, S.R.; Baynes, J.W.; Bayliss, M.T.; Bijlsma, J.W.J.; Lafeber, F.P.J.G.; TeKoppele, J.M.

    2000-01-01

    Non-enzymic modification of tissue proteins by reducing sugars, the so-called Maillard reaction, is a prominent feature of aging. In articular cartilage, relatively high levels of the advanced glycation end product (AGE) pentosidine accumulate with age. Higher pentosidine levels have been associated

  16. Thermal luminescence spectra of polyamides and their Maillard reaction with reducing sugars.

    Science.gov (United States)

    Karakisawa, Taketo; Yamada, Taishi; Sekine, Masahiko; Ishii, Hiroshi; Satoh, Chikahiro; Millington, Keith R; Nakata, Munetaka

    2012-01-01

    Thermal luminescence (TL) spectra of polyamides were measured with a Fourier-transform chemiluminescence spectrometer to elucidate the emission mechanism. A TL band of ε-polylysine with a peak at 542 nm observed at 403 K was assigned to the emission due to the interaction of the -CO-NH- group with oxygen molecules by comparison with nylon-6, polyglycine, and polyalanine. When the sample was kept at 453 K, the intensity of the TL band decreased and the wavelength of the peak shifted to 602 nm, which was assigned to the emission due to the interaction of the NH2 group on the side chain with oxygen molecules by comparison with monomeric lysine. A weak emission with a peak at 668 nm was assigned to the advanced glycosylation end products (AGEs) yielded by the Maillard reaction with a catalytic amount of water. To understand this reaction and to examine the TL emission of AGEs, we measured TL spectra of mixtures of polylysine and reducing sugars such as glucose, maltose, lactose, and dextrin. The minimum temperature for TL emission, wavelength of the peak and the relative intensities of the TL emission were found to depend on the size of the sugars.

  17. Food Processing and Maillard Reaction Products: Effect on Human Health and Nutrition.

    Science.gov (United States)

    Tamanna, Nahid; Mahmood, Niaz

    2015-01-01

    Maillard reaction produces flavour and aroma during cooking process; and it is used almost everywhere from the baking industry to our day to day life to make food tasty. It is often called nonenzymatic browning reaction since it takes place in the absence of enzyme. When foods are being processed or cooked at high temperature, chemical reaction between amino acids and reducing sugars leads to the formation of Maillard reaction products (MRPs). Depending on the way the food is being processed, both beneficial and toxic MRPs can be produced. Therefore, there is a need to understand the different types of MRPs and their positive or negative health effects. In this review we have summarized how food processing effects MRP formation in some of the very common foods.

  18. Food Processing and Maillard Reaction Products: Effect on Human Health and Nutrition

    Directory of Open Access Journals (Sweden)

    Nahid Tamanna

    2015-01-01

    Full Text Available Maillard reaction produces flavour and aroma during cooking process; and it is used almost everywhere from the baking industry to our day to day life to make food tasty. It is often called nonenzymatic browning reaction since it takes place in the absence of enzyme. When foods are being processed or cooked at high temperature, chemical reaction between amino acids and reducing sugars leads to the formation of Maillard reaction products (MRPs. Depending on the way the food is being processed, both beneficial and toxic MRPs can be produced. Therefore, there is a need to understand the different types of MRPs and their positive or negative health effects. In this review we have summarized how food processing effects MRP formation in some of the very common foods.

  19. Characterisation of bovine serum albumin-fucoidan conjugates prepared via the Maillard reaction.

    Science.gov (United States)

    Kim, Do-Yeong; Shin, Weon-Sun

    2015-04-15

    Bovine serum albumin (BSA)-fucoidan conjugates were prepared by the Maillard reaction (60 °C and 79% relative humidity for 96 h), and were then identified by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and size-exclusion chromatography (SEC). Molecular characteristics of the BSA-fucoidan conjugates were investigated, using atomic force microscopy (AFM), dynamic light scattering (DLS), fluorescence spectroscopy, and circular dichroism spectroscopy. SDS-PAGE patterns provided evidence for the covalent bonding between BSA and fucoidan. SEC profiles showed that about 1.5-2.0 mol of fucoidan were covalently linked to 1 mol of BSA, resulting in high-molecular-weight compositions (conjugates). AFM images and DLS results indicated that most particles in the conjugates were nano-structured and more spherical than those of a regular BSA-fucoidan mixture. The fluorescence intensity and maximum emission wavelength of the conjugates together revealed that the BSA molecules had converted from an ordered conformation into a partially folded molten globule state.

  20. Chemical characteristics and enhanced hepatoprotective activities of Maillard reaction products derived from milk protein-sugar system.

    Science.gov (United States)

    Oh, Nam Su; Young Lee, Ji; Lee, Hyun Ah; Joung, Jae Yeon; Shin, Yong Kook; Kim, Sae Hun; Kim, Younghoon; Lee, Kwang Won

    2016-02-01

    The objective of this study was to investigate the characteristics, antioxidative properties, and hepatoprotective effects of Maillard reaction products (MRP) from milk protein reacted with sugars. The MRP were obtained from milk protein, whey protein concentrates and sodium caseinate, using 2 types of sugars, lactose and glucose, by heating the mixture at 55°C for 7d in a sodium phosphate buffer (pH 7.4). Changes in the chemical modification of the milk protein were monitored by measuring the protein-bound carbonyls and PAGE protein profiles. The results showed that the amount of protein-bound carbonyls increased after Maillard reaction (MR). In addition, sodium dodecyl sulfate-PAGE analysis indicated a formation of high-molecular weight complexes through MR. The modification sites induced by MR of milk protein were monitored by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of tryptic-digested gel spots of MRP. As a result, modification and their localization in AA sequence of MRP was identified. Also, the MRP showed higher antioxidant activities than the intact milk protein, and they reduced intracellular reactive oxygen species production and inhibited the depletion of the reduced glutathione concentrations in the HepG2 cells. In particular, glucose-sodium caseinate MRP showed the highest biological activities among all MRP. Therefore, these results suggest that the MRP from milk protein reacting with sugars possess effective antioxidant activity and have a protective ability against oxidative damage.

  1. Fluorescence from the maillard reaction and its potential applications in food science.

    Science.gov (United States)

    Matiacevich, Silvia B; Santagapita, Patricio R; Buera, M Pilar

    2005-01-01

    The chemistry of the Maillard reaction involves a complex set of steps, and its interpretation represents a challenge in basic and applied aspects of Food Science. Fluorescent compounds have been recognized as important early markers of the reaction in food products since 1942. However, the recent advances in the characterization of fluorophores' development were observed in biological and biomedical areas. The in vivo non-enzymatic glycosylation of proteins produces biological effects, promoting health deterioration. The characteristic fluorescence of advanced glycosylation end products (AGEs) is similar to that of Maillard food products and represents an indicator of the level of AGE-modified proteins, but the structure of the fluorescent groups is, typically, unknown. Application of fluorescence measurement is considered a potential tool for addressing key problems of food deterioration as an early marker or index of the damage of biomolecules. Fluorophores may be precursors of the brown pigments and/or end products. A general scheme of the Maillard reaction is proposed in this article, incorporating the pool concept. A correct interpretation of the effect of environmental and compositional conditions and their influences on the reaction kinetics may help to define the meaning of fluorescence development for each particular system.

  2. Antibacterial Characteristics and Activity of Water-Soluble Chitosan Derivatives Prepared by the Maillard Reaction

    Directory of Open Access Journals (Sweden)

    Ying-Chien Chung

    2011-10-01

    Full Text Available The antibacterial activity of water-soluble chitosan derivatives prepared by Maillard reactions against Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Escherichia coli, Shigella dysenteriae, and Salmonella typhimurium was examined. Relatively high antibacterial activity against various microorganisms was noted for the chitosan-glucosamine derivative as compared to the acid-soluble chitosan. In addition, it was found that the susceptibility of the test organisms to the water-soluble chitosan derivative was higher in deionized water than in saline solution. Metal ions were also found to reduce the antibacterial activity of the water-soluble chitosan derivative on S. aureus. The marked increase in glucose level, protein content and lactate dehydrogenase (LDH activity was observed in the cell supernatant of S. aureus exposed to the water-soluble chitosan derivative in deionized water. The results suggest that the water-soluble chitosan produced by Maillard reaction may be a promising commercial substitute for acid-soluble chitosan.

  3. Urinary excretion of dietary maillard reaction products in healthy adult female cats

    NARCIS (Netherlands)

    Rooijen, van C.; Bosch, G.; Butre, C.I.; Poel, van der A.F.B.; Wierenga, P.A.; Alexander, L.; Hendriks, W.H.

    2016-01-01

    Download »Citation Alerts »Sign up for TOC email alerts Share »Email this content »Recommend to librarian Facebook Twitter doi:10.2527/jas.2015-9550 Urinary excretion of dietary Maillard reaction products in healthy adult female cats12 C. van Rooijen*, G. Bosch 3*, C. I. Butré†, A. F. B. van der Poe

  4. Effects of Maillard reaction on flavor and safety of Chinese traditional food: roast duck.

    Science.gov (United States)

    Zhou, Yiming; Xie, Fan; Zhou, Xiaoli; Wang, Yuqiang; Tang, Wen; Xiao, Ying

    2016-04-01

    Roast duck is one kind of representative roast food whose flavor is mainly produced by the Maillard reaction. However, some potentially toxic compounds are generated in the thermal process and are a potential health risk. The aim of this work was to analyze the effects of the Maillard reaction on flavor and safety of a Chinese traditional food: roast duck. Ducks with different roasting times (0, 10, 20, 30, 40, 50 and 60 min) were analyzed. The 40 and 50 min roast ducks exhibited an acceptable degree of sensory attributes, but the 60 min roast duck showed the most abundant aroma compounds. Antioxidant activities were observed to increase with roasting, and the 60 min roast duck showed the highest antioxidant activities (1,1-diphenylpicryhydrazyl, 39.3 µmol Trolox g(-1) sample). The highest content of acrylamide (0.21 µg g(-1)) and 5-hydroxymethylfurfural (0.089 µg g(-1)) were detected in the 50 and 60 min roast duck extract, respectively. Furthermore, water extract from 60 min roast ducks manifested a higher lactose dehydrogenase release ratio (51.9%) and greatly increased cell apoptosis. The drastic Maillard reaction in duck induced by long roasting time could be advantageous for color, aroma and antioxidant activities in roast ducks, but might be not beneficial to health. © 2015 Society of Chemical Industry.

  5. The Maillard reaction and pet food processing: effects on nutritive value and pet health.

    Science.gov (United States)

    van Rooijen, Charlotte; Bosch, Guido; van der Poel, Antonius F B; Wierenga, Peter A; Alexander, Lucille; Hendriks, Wouter H

    2013-12-01

    The Maillard reaction, which can occur during heat processing of pet foods or ingredients, is known to reduce the bioavailability of essential amino acids such as lysine due to the formation of early and advanced Maillard reaction products (MRP) that are unavailable for utilisation by the body. Determination of the difference between total and reactive lysine by chemical methods provides an indication of the amount of early MRP present in foods, feeds and ingredients. Previous research reported that the difference between total and reactive lysine in pet foods can be up to 61.8%, and foods for growing dogs may be at risk of supplying less lysine than the animal may require. The endogenous analogues of advanced MRP, advanced glycation endproducts, have been associated with age-related diseases in humans, such as diabetes and impaired renal function. It is unknown to what extent advanced MRP are present in pet foods, and if dietary MRP can be associated with the development of diseases such as diabetes and impaired renal function in pet animals. Avoidance of ingredients with high levels of MRP and processing conditions known to favour the Maillard reaction may be useful strategies to prevent the formation of MRP in manufactured pet food. Future work should further focus on understanding the effects of ingredient choice and processing conditions on the formation of early and advanced MRP, and possible effects on animal health.

  6. Maillard Reaction in Natural Rubber Latex: Characterization and Physical Properties of Solid Natural Rubber

    Directory of Open Access Journals (Sweden)

    S. Montha

    2016-01-01

    Full Text Available Maillard reaction in Natural Rubber (NR latex was investigated by treating fresh NR latex with glutaraldehyde (C5H8O2 in amounts of 0, 50, 100, and 200 mmol/kg of latex. Protein cross-linking in fresh NR latex and solid NR was confirmed by using sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE and attenuated total reflection infrared (ATR-IR spectroscopy, respectively. It was found that degree of protein cross-linking in NR increased with increasing C5H8O2 concentration. Physical properties of untreated and treated NR substances in terms of gel content, initial Wallace plasticity (P0, plasticity retention index (PRI, Mooney viscosity, and tensile strength were carefully explored. Results clearly showed that the Maillard cross-linking of proteins had remarkable effect on bulk NR properties, that is, solvent resistance, hardness, resistance to oxidation, rheological behavior, and resistance to stretching out.

  7. Effect of Saccharide Structure and Size on the Degree of Substitution and Product Dispersity of a-Lactalbumin Glycated via the Maillard Reaction

    NARCIS (Netherlands)

    Haar, ter R.; Schols, H.A.; Gruppen, H.

    2011-01-01

    The course of the Maillard reaction between a-lactalbumin and various mono- and oligosaccharides in the solid state was studied using UPLC–ESI-TOF-MS. Individual reaction products were monitored for their degree of substitution per protein molecule (DSP). The Maillard reaction rate depended on the s

  8. The effects of phytic acid on the Maillard reaction and the formation of acrylamide.

    Science.gov (United States)

    Wang, Huan; Zhou, Yamin; Ma, Jimei; Zhou, Yuanyuan; Jiang, Hong

    2013-11-01

    Phytic acid, myo-inositol hexaphosphoric acid, exists in substantial (1-5%) amounts in edible plant seeds. In this study the effects of phytic acid on the Maillard reaction and the formation of acrylamide were investigated. Both phytic acid and phosphate enhanced browning in glucose/β-alanine system, but phytic acid was less effective than phosphate. Higher pH favoured the catalytic activities for both of them. The influence of the types of sugar and amino acid on the reaction was also examined. Browning was suppressed by the addition of calcium and magnesium ions, but an additive effect was observed for ferrous ions and phytic acid in glucose/β-alanine solution at pH 8.0. Both phytic acid and phosphate promoted the polymerisation of the reaction intermediates. The kinetics of Maillard reaction was first-ordered reaction in the presence of phytic acid. Phytic acid was less effective than phosphate in the formation of acrylamide. When potato slices were treated with sodium phytate and calcium chloride successively, the formation of acrylamide was greatly suppressed.

  9. Maillard reaction versus other nonenzymatic modifications in neurodegenerative processes.

    Science.gov (United States)

    Pamplona, Reinald; Ilieva, Ekaterina; Ayala, Victoria; Bellmunt, Maria Josep; Cacabelos, Daniel; Dalfo, Esther; Ferrer, Isidre; Portero-Otin, Manuel

    2008-04-01

    Nonenzymatic protein modifications are generated from direct oxidation of amino acid side chains and from reaction of the nucleophilic side chains of specific amino acids with reactive carbonyl species. These reactions give rise to specific markers that have been analyzed in different neurodegenerative diseases sharing protein aggregation, such as Alzheimer's disease, Pick's disease, Parkinson's disease, dementia with Lewy bodies, Creutzfeldt-Jakob disease, and amyotrophic lateral sclerosis. Collectively, available data demonstrate that oxidative stress homeostasis, mitochondrial function, and energy metabolism are key factors in determining the disease-specific pattern of protein molecular damage. In addition, these findings suggest the lack of a "gold marker of oxidative stress," and, consequently, they strengthen the need for a molecular dissection of the nonenzymatic reactions underlying neurodegenerative processes.

  10. The ribose and glycine Maillard reaction in the interstellar medium (ISM): A theoretical study

    Indian Academy of Sciences (India)

    Abraham F Jalbout; Md Abul Haider Shipar

    2008-05-01

    Possibility of the Maillard reaction to take place in the gaseous phase in the interstellar medium was investigated by using Density Functional Theory (DFT) computations. Cyclic ribose (c-Rib)/open-chain ribose (c-Rib) and glycine were taken as the model. Mechanisms have been proposed, and possibility of the formation of different compounds have been evaluated through calculating the Gibb’s free energy changes for different steps of the reaction by following the total mass balance. The result reveals that both c-Rib and Rib can participate in the reaction, and c-Rib is more efficient than Rib. The reactions under basic and neutral conditions are supposed to be the first and second most favourable. Acidic conditions and the isoelectric point of glycine were unfeasible for the reaction. The kinetics of the mechanics are briefly addressed in this work.

  11. The Maillard reaction--illicite (bio)chemistry in tissues and food.

    Science.gov (United States)

    Robert, L; Robert, A-M; Labat-Robert, J

    2011-12-01

    We present a review of our early work on the Maillard reaction, at the interface of food chemistry and tissue biochemistry, as well as the reinterpretation of our early findings in the light of recent advances in the chemistry of the involved reactions. These concern specifically the role of lower aldehydes, produced during the glycolytic pathways and especially acetaldehyde. We also review some of our recent findings on the cytotoxic and genotoxic aspect of these "illicit" organic reactions, taking place in tissues (and also in food products) besides the genetically "programmed" metabolic pathways. Some recent results in organic-pharmaceutical chemistry confirm the potential importance of the reviewed reactions both in food chemistry and in tissues as well as the pathological importance of reactions taking place in tissues.

  12. High-Pressure-High-Temperature Processing Reduces Maillard Reaction and Viscosity in Whey Protein-Sugar Solutions.

    Science.gov (United States)

    Avila Ruiz, Geraldine; Xi, Bingyan; Minor, Marcel; Sala, Guido; van Boekel, Martinus; Fogliano, Vincenzo; Stieger, Markus

    2016-09-28

    The aim of the study was to determine the influence of pressure in high-pressure-high-temperature (HPHT) processing on Maillard reactions and protein aggregation of whey protein-sugar solutions. Solutions of whey protein isolate containing either glucose or trehalose at pH 6, 7, and 9 were treated by HPHT processing or conventional high-temperature (HT) treatments. Browning was reduced, and early and advanced Maillard reactions were retarded under HPHT processing at all pH values compared to HT treatment. HPHT induced a larger pH drop than HT treatments, especially at pH 9, which was not associated with Maillard reactions. After HPHT processing at pH 7, protein aggregation and viscosity of whey protein isolate-glucose/trehalose solutions remained unchanged. It was concluded that HPHT processing can potentially improve the quality of protein-sugar-containing foods, for which browning and high viscosities are undesired, such as high-protein beverages.

  13. Evolution of the Maillard Reaction in Glutamine or Arginine-Dextrinomaltose Model Systems

    Directory of Open Access Journals (Sweden)

    Silvia Pastoriza

    2016-12-01

    Full Text Available Enteral formulas are foods designed for medical uses to feed patients who are unable to eat normally. They are prepared by mixing proteins, amino acids, carbohydrates and fats and submitted to sterilization. During thermal treatment, the Maillard reaction takes place through the reaction of animo acids with reducing sugars. Thus, although glutamine and arginine are usually added to improve the nutritional value of enteral formulas, their final concentration may vary. Thus, in the present paper the early, intermediate, and advanced states of the Maillard reaction were studied in model systems by measuring loss of free amino acids through the decrease of fluorescence intensity with o-phtaldialdehyde (OPA, 5-Hydroximethylfurfural (HMF, furfural, glucosylisomaltol, fluorescence, and absorbance at 420 nm. The systems were prepared by mixing glutamine or arginine with dextrinomaltose (similar ingredients to those used in special enteral formula, and heated at 100 °C, 120 °C and 140 °C for 0 to 30 min. The recorded changes in the concentration of furanic compounds was only useful for longer heating times of high temperatures, while absorbance and fluorescence measurements were useful in all the assayed conditions. In addition, easiness and sensitivity of absorbance and fluorescence make them useful techniques that could be implemented as indicators for monitoring the manufacture of special enteral formulas. Glucosylisomaltol is a useful indicator to monitor the manufacture of glutamine-enriched enteral formulas.

  14. Evolution of the Maillard Reaction in Glutamine or Arginine-Dextrinomaltose Model Systems

    Science.gov (United States)

    Pastoriza, Silvia; Rufián-Henares, José Ángel; García-Villanova, Belén; Guerra-Hernández, Eduardo

    2016-01-01

    Enteral formulas are foods designed for medical uses to feed patients who are unable to eat normally. They are prepared by mixing proteins, amino acids, carbohydrates and fats and submitted to sterilization. During thermal treatment, the Maillard reaction takes place through the reaction of animo acids with reducing sugars. Thus, although glutamine and arginine are usually added to improve the nutritional value of enteral formulas, their final concentration may vary. Thus, in the present paper the early, intermediate, and advanced states of the Maillard reaction were studied in model systems by measuring loss of free amino acids through the decrease of fluorescence intensity with o-phtaldialdehyde (OPA), 5-Hydroximethylfurfural (HMF), furfural, glucosylisomaltol, fluorescence, and absorbance at 420 nm. The systems were prepared by mixing glutamine or arginine with dextrinomaltose (similar ingredients to those used in special enteral formula), and heated at 100 °C, 120 °C and 140 °C for 0 to 30 min. The recorded changes in the concentration of furanic compounds was only useful for longer heating times of high temperatures, while absorbance and fluorescence measurements were useful in all the assayed conditions. In addition, easiness and sensitivity of absorbance and fluorescence make them useful techniques that could be implemented as indicators for monitoring the manufacture of special enteral formulas. Glucosylisomaltol is a useful indicator to monitor the manufacture of glutamine-enriched enteral formulas.

  15. A combination of quantitative marinating and Maillard reaction to enhance volatile flavor in Chinese marinated chicken.

    Science.gov (United States)

    Wei, Xiuli; Wang, Chunqing; Zhang, Chunhui; Li, Xia; Wang, Jinzhi; Li, Hai; Tang, Chunhong

    2017-02-01

    A combination of quantitative marinating and Maillard reaction was investigated by adding d-xylose, l-cysteine and thiamine to the marinated brine of quantitative marinating, which was expected to enhance the volatile flavor of Chinese marinated chicken. Response surface methodology was used to optimize parameters, in which response was sensory evaluation scores of marinated chicken. A Box-Behnken center design was applied to the optimized added contents. The optimized contents were d-xylose (1-5‰), l-cysteine (1-5‰) and thiamine (1-3‰). Analysis of variance indicated that a second-order polynomial equation could predict the experimental data well (R(2)  = 0.94), and sensory evaluation scores were significantly affected by the added amount of d-xylose, l-cysteine and thiamine. The optimal conditions that maximized the sensory evaluation score of Chinese marinated chicken were found to be 4.96‰ d-xylose, 2.28‰ l-cysteine and 2.66‰ thiamine (w/w). Given these optimal conditions, a number of meat-like flavor compounds such as 2-pentyl-furan, benzothiazole and 4-methyl-5-thiazoleethanol were identified by gas chromatographic-mass spectrometric analysis. Our results suggested that a combination of quantitative marinating and Maillard reaction might be a promising method to enhance the volatile flavor, especially meat-like flavor, of Chinese marinated chicken. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  16. Microencapsulation of stearidonic acid soybean oil in Maillard reaction-modified complex coacervates.

    Science.gov (United States)

    Ifeduba, Ebenezer A; Akoh, Casimir C

    2016-05-15

    The antioxidant capacity of Maillard reaction (MR)-modified gelatin (GE)-gum arabic (GA) coacervates was optimized to produce microcapsules with superior oxidative stability compared to the unmodified control. MR was used to crosslink GE and GA, with or without maltodextrin (MD), to produce anti-oxidative Maillard reaction products (MRP) which was used to encapsulate stearidonic acid soybean oil (SDASO) by complex coacervation. Biopolymer blends (GE-GA [1:1, w/w] or GE-GA-MD [2:2:1, w/w/w]) were crosslinked by dry-heating at 80°C for 4, 8, or 16h. Relationships between the extent of browning, Trolox equivalent antioxidant capacity (TEAC), and the total oxidation (TOTOX) of encapsulated SDASO were fitted to quadratic models. The [GE-GA-MD] blends exhibited higher browning rates and TEAC values than corresponding [GE-GA] blends. Depending on the type of biopolymer blend and dry-heating time, TOTOX values of SDASO in MRP-derived microcapsules were 29-87% lower than that of the non-crosslinked control after 30 days of storage.

  17. Safety assessment of Maillard reaction products of chicken bone hydrolysate using Sprague-Dawley rats

    Directory of Open Access Journals (Sweden)

    Jin-Zhi Wang

    2016-03-01

    Full Text Available Background: The Maillard reaction products of chicken bone hydrolysate (MRPB containing 38% protein, which is a derived product from chicken bone, is usually used as a flavor enhancer or food ingredient. In the face of a paucity of reported data regarding the safety profile of controversial Maillard reaction products, the potential health effects of MRPB were evaluated in a subchronic rodent feeding study. Methods: Sprague–Dawley rats (SD, 5/sex/group were administered diets containing 9, 3, 1, or 0% of MRPB derived from chicken bone for 13 weeks. Results: During the 13-week treatment period, no mortality occurred, and no remarkable changes in general condition and behavior were observed. The consumption of MRPB did not have any effect on body weight or feed and water consumption. At the same time, there was no significant increase in the weights of the heart, liver, lung, kidney, spleen, small intestine, and thymus in groups for both sexes. Serological examination showed serum alanine aminotransferase in both sexes was decreased significantly, indicating liver cell protection. No treatment-related histopathological differences were observed between the control and test groups. Conclusion: Based on the results of this study, the addition of 9% MRPB in the diet had no adverse effect on both male and female SD rats during the 90-day observation. Those results would provide useful information on the safety of a meaty flavor enhancer from bone residue as a byproduct of meat industry.

  18. Formation of cysteine-S-conjugates in the Maillard reaction of cysteine and xylose.

    Science.gov (United States)

    Cerny, Christoph; Guntz-Dubini, Renée

    2013-11-15

    Cysteine-S-conjugates (CS-conjugates) occur in foods derived from plant sources like grape, passion fruit, onion, garlic, bell pepper and hops. During eating CS-conjugates are degraded into aroma-active thiols by β-lyases that originate from oral microflora. The present study provides evidence for the formation of the CS-conjugates S-furfuryl-l-cysteine (FFT-S-Cys) and S-(2-methyl-3-furyl)-l-cysteine (MFT-S-Cys) in the Maillard reaction of xylose with cysteine at 100°C for 2h. The CS-conjugates were isolated using cationic exchange and reversed-phase chromatography and identified by (1)H NMR, (13)C NMR and LC-MS(2). Spectra and LC retention times matched those of authentic standards. To the best of our knowledge, this is the first time that CS-conjugates are described as Maillard reaction products. Furfuryl alcohol (FFA) is proposed as an intermediate which undergoes a nucleophilic substitution with cysteine. Both FFT-S-Cys and MFT-S-Cys are odourless but produce strong aroma when tasted in aqueous solutions, supposedly induced by β -lyases from the oral microflora. The perceived aromas resemble those of the corresponding aroma-active thiols 2-furfurylthiol (FFT) and 2-methyl-3-furanthiol (MFT) which smell coffee-like and meaty, respectively.

  19. Formation of early and advanced Maillard reaction products correlates to the ripening of cheese.

    Science.gov (United States)

    Spanneberg, Robert; Salzwedel, Grit; Glomb, Marcus A

    2012-01-18

    The present study deals with the characterization of the ripening of cheese. A traditional German acid curd cheese was ripened under defined conditions at elevated temperature, and protein and amino acid modifications were investigated. Degree of proteolysis and analysis of early [Amadori compound furosine (6)] and advanced [N(ε)-carboxymethyllysine (4), N(ε)-carboxyethyllysine (5)] Maillard reaction products confirmed the maturation to proceed from the rind to the core of the cheese. Whereas 6 was decreased, 4 and 5 increased over time. Deeper insight into the Maillard reaction during the ripening of cheese was achieved by the determination of selected α-dicarbonyl compounds. Especially methylglyoxal (2) showed a characteristic behavior during storage of the acid curd cheese. Decrease of this reactive structure was directly correlated to the formation of 5. To extend the results of experimental ripening to commercial cheeses, different aged Gouda types were investigated. Maturation times of the samples ranged from 6 to 8 weeks (young) to more than 1 year (aged). Again, increase of 5 and decrease of 2 were able to describe the ripening of this rennet coagulated cheese. Therefore, both chemical parameters are potent markers to characterize the degree of maturation, independent of coagulation.

  20. Evaluation of the extent of initial Maillard reaction during cooking some vegetables by direct measurement of the Amadori compounds.

    Science.gov (United States)

    Yu, Jiahao; Zhang, Shuqin; Zhang, Lianfu

    2017-06-02

    During vegetable cooking, one of the most notable and common chemical reactions is the Maillard reaction, which occurs as a result of thermal treatment and dehydration. Amadori compound determination provides a very sensitive indicator for early detection of quality changes caused by the Maillard reaction, as well as to retrospectively assess the heat treatment or storage conditions to which the product has been subjected. In this paper, a hydrophilic interaction liquid chromatographic-electrospray ionization-tandem mass spectrometric method was developed for the analysis of eight Amadori compounds, and the initial steps of the Maillard reaction during cooking (steaming, frying and baking) bell pepper, red pepper, yellow onion, purple onion, tomato and carrot were also assessed by quantitative determination of these Amadori compounds. These culinary treatments reduced moisture and increased the total content of Amadori compounds, which was not dependent on the type of vegetable or cooking method. Moreover, the effect of steaming on Amadori compound content and water loss was less than that by baking and frying vegetables. Further studies showed that the combination of high temperature and short time may lead to lower formation of Amadori compounds when baking vegetables. Culinary methods differently affected the extent of initial Maillard reaction when vegetables were made into home-cooked products. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  1. Role of choline and glycine betaine in the formation of N,N-dimethylpiperidinium (mepiquat) under Maillard reaction conditions.

    Science.gov (United States)

    Bessaire, Thomas; Tarres, Adrienne; Stadler, Richard H; Delatour, Thierry

    2014-01-01

    This study is the first to examine the role of choline and glycine betaine, naturally present in some foods, in particular in cereal grains, to generate N,N-dimethylpiperidinium (mepiquat) under Maillard conditions via transmethylation reactions involving the nucleophile piperidine. The formation of mepiquat and its intermediates piperidine - formed by cyclisation of free lysine in the presence of reducing sugars - and N-methylpiperidine were monitored over time (240°C, up to 180 min) using high-resolution mass spectrometry in a model system comprised of a ternary mixture of lysine/fructose/alkylating agent (choline or betaine). The reaction yield was compared with data recently determined for trigonelline, a known methylation agent present naturally in coffee beans. The role of choline and glycine betaine in nucleophilic displacement reactions was further supported by experiments carried out with stable isotope-labelled precursors (¹³C- and deuterium-labelled). The results unequivocally demonstrated that the piperidine ring of mepiquat originates from the carbon chain of lysine, and that either choline or glycine betaine furnishes the N-methyl groups. The kinetics of formation of the corresponding demethylated products of both choline and glycine betaine, N,N-demethyl-2-aminoethanol and N,N-dimethylglycine, respectively, were also determined using high-resolution mass spectrometry.

  2. High-Pressure-High-Temperature Processing Reduces Maillard Reaction and Viscosity in Whey Protein-Sugar Solutions

    NARCIS (Netherlands)

    Avila Ruiz, Geraldine; Xi, Bingyan; Minor, Marcel; Sala, Guido; Boekel, van Tiny; Fogliano, Vincenzo; Stieger, Markus

    2016-01-01

    The aim of the study was to determine the influence of pressure in high-pressure–high-temperature (HPHT) processing on Maillard reactions and protein aggregation of whey protein–sugar solutions. Solutions of whey protein isolate containing either glucose or trehalose at pH 6, 7, and 9 were treated

  3. Effects of beetroot (Beta vulgaris) preparations on the Maillard reaction products in milk and meat-protein model systems

    NARCIS (Netherlands)

    Rackauskienea, I.; Pukalskas, A.; Rimantas Venskutonis, P.; Fiore, A.M.; Troise, A.D.; Fogliano, V.

    2015-01-01

    The effects of beetroots (Beta vulgaris) on the formation of Maillard reaction (MR) products possessing health, nutritional and sensory implications were studied. The effect of dried beetroot juice on the formation of Ne-(carboxymethyl)lysine (CML) and Ne-(2-furoylmethyl)-L-lysine (furosine) was det

  4. Effect of different molecular weight chitosans on the mitigation of acrylamide formation and the functional properties of the resultant Maillard reaction products.

    Science.gov (United States)

    Chang, Yu-Wei; Sung, Wen-Chieh; Chen, Jing-Yi

    2016-05-15

    Mitigation of acrylamide formation and the functional properties of Maillard reaction products (MRPs) were investigated in a food model system. The system was composed of elements of mixtures and their combination including fructose, asparagine and different molecular weight chitosans. All solutions were heated, and then analyzed for acrylamide content, MRPs absorbance, pH, color, antioxidant capacity, antibacterial activity and kinematic viscosity. The fructose, asparagine and chitosan mixture had more MRPs compared to other mixtures. 1,1-Diphenyl-2-pricrylhydrazy (DPPH) radical scavenging activities, ferrous ion chelating abilities and reducing power results showed that all solutions containing a combination of two or three reactants had antioxidant capacities. Acrylamide content has a positive correlation with absorbance values at OD294 and OD420 but a negative correlation with the CIB L(∗) value of a solution (pacrylamide.

  5. Oxidation as an important factor of protein damage: Implications for Maillard reaction

    Indian Academy of Sciences (India)

    L Trnková; J Dršata; I Boušová

    2015-06-01

    Protein oxidation, the process caused especially by reactive oxygen and nitrogen species, is thought to play a major role in various oxidative processes within cells and is implicated in the development of many human diseases. This review provides a brief overview of the protein oxidation with the emphasis on the types of oxidation (oxidation of protein backbone and amino acid residues side chains, site-specific metal-catalysed protein oxidation), oxidation-dependent generation of protein hydroperoxides, carbonyl derivatives and protein–protein cross-linkages. Non-enzymatic glycoxidation (also known as Maillard reaction) as an important factor of protein damage, consequences of oxidative protein impairment and related diseases as well as means of monitoring and assessment of protein modifications are discussed.

  6. Functional properties of nisin-carbohydrate conjugates formed by radiation induced Maillard reaction

    Science.gov (United States)

    Muppalla, Shobita R.; Sonavale, Rahul; Chawla, Surinder P.; Sharma, Arun

    2012-12-01

    Nisin-carbohydrate conjugates were prepared by irradiating nisin either with glucose or dextran. Increase in browning and formation of intermediate products was observed with a concomitant decrease in free amino and reducing sugar groups indicating occurrence of the Maillard reaction catalyzed by irradiation. Nisin-carbohydrate conjugates showed a broad spectrum antibacterial activity against Gram negative bacteria (Escherichia coli, Pseudomonas fluorescence) as well as Gram positive bacteria (Staphylococcus aureus, Bacillus cereus). Results of antioxidant assays, including that of DPPH radical-scavenging activity and reducing power, showed that the nisin-dextran conjugates possessed better antioxidant potential than nisin-glucose conjugate. These results suggested that it was possible to enhance the functional properties of nisin by preparing radiation induced conjugates suitable for application in food industry.

  7. Urinary excretion of dietary Maillard reaction products in healthy adult female cats.

    Science.gov (United States)

    van Rooijen, C; Bosch, G; Butré, C I; van der Poel, A F B; Wierenga, P A; Alexander, L; Hendriks, W H

    2016-01-01

    During processing of foods, the Maillard reaction occurs, resulting in the formation of advanced Maillard reaction products (MRP). Varying amounts of MRP have been found in commercially processed pet foods. Dietary MRP can be absorbed and contribute to the endogenous pool of MRP and possibly the etiology of age-related diseases. The aim of the present study was to determine urinary excretion of dietary MRP in cats fed commercial moist and dry foods. A pilot study with 10 cats, conducted to determine the adaptation time required for stable urinary excretion of MRP when changing to a diet with contrasting MRP content, showed an adaptation time of 1 d for all components. In the main study, 6 commercially processed dry and 6 moist diets were fed to 12 adult female cats in 2 parallel randomized, 36-d Latin square designs. The 24-h urine was collected quantitatively using modified litter boxes, and fructoselysine (FL), carboxymethyllysine (CML), and lysinoalanine (LAL) were analyzed using ultra high performance liquid chromatography (UHPLC) - mass spectrometer. Daily urinary excretion of FL and CML showed a positive relationship with daily intake in the dry ( = 0.03 and cats and excreted in the urine. The adaptation time with change in diet indicates a likely effective excretion of MRP. Minimum apparent absorption of FL, CML, and LAL was found to range between 8% and 23%, 25% and 73%, and 6% and 19%, respectively. The observed decrease in urinary recovery suggests a limiting factor in digestion, absorption, metabolism, or urinary excretion. This study shows that dietary MRP in commercial diets are absorbed and excreted via the kidneys in cats.

  8. Implications of the Maillard reaction on bovine alpha-lactalbumin and its proteolysis during in vitro infant digestion.

    Science.gov (United States)

    Joubran, Yousef; Moscovici, Alice; Portmann, Reto; Lesmes, Uri

    2017-06-21

    This study investigated the functionality and digestibility of Maillard reaction products (MRPs) of alpha-lactalbumin (α-la), a major whey protein and component of infant formulas. The impact of different carbohydrates (glucose, galactose or galacto-oligosaccharides (GOS)) and heating duration was studied. SDS-PAGE, UV and color measurements monitored reaction extent, which varied between carbohydrates whereby galactose reacted more readily than glucose. Surface hydrophobicity and antioxidant capacity were found to be significantly (p < 0.05) higher following Maillard conjugation, with GOS-based MRPs elevating antioxidant capacity ∼50-fold compared to α-la. In addition, the digestive proteolysis of MRPs was evaluated using an infant in vitro gastro-duodenal model. SDS-PAGE analyses of digesta revealed Maillard conjugation generally increased α-la's susceptibility to proteolysis. Interestingly, GOS-based MRPs presented an optimization challenge, since heating for 12 h delayed proteolysis, while extended heating resulted in the highest susceptibility to proteolysis. Proteomic analyses further demonstrated the differences in enzymatic cleavage patterns and helped identify bioactive peptides rendered bioaccessible during the digestion of α-la or its MRPs. Bioinformatic mining of the proteomic data using PeptideRanker also gave rise to two potentially novel bioactive peptides, FQINNKIW and GINYWLAHKALCS. Finally, antioxidant capacity of luminal contents, measured by DPPH, revealed Maillard conjugation increased the antioxidant capacity of both gastric and duodenal digesta. Overall, this work draws a link between the Maillard reaction, digestive proteolysis and the bioaccessibility of bioactive peptides and antioxidant species in the infant alimentary canal. This could help rationally process infant formulas towards improved nutritional and extra-nutritional benefits.

  9. Kinetics of the glucose/glycine Maillard reaction pathways: influences of pH and reactant initial concentrations

    NARCIS (Netherlands)

    Martins, S.I.F.S.; Boekel, van M.A.J.S.

    2005-01-01

    A previously proposed kinetic model for the glucose/glycine Maillard reaction pathways has been validated by changing the initial pH (4.8, 5.5, 6.0, 6.8 and 7.5) of the reaction and reactant initial concentrations (1:2 and 2:1 molar ratios were compared to the 1:1 ratio). The model consists of 10

  10. Impact of high-intensity ultrasound on the formation of lactulose and Maillard reaction glycoconjugates.

    Science.gov (United States)

    Corzo-Martínez, Marta; Montilla, Antonia; Megías-Pérez, Roberto; Olano, Agustín; Moreno, F Javier; Villamiel, Mar

    2014-08-15

    The impact of high-intensity ultrasound (US) on the formation of lactulose during lactose isomerization and on the obtention of lysine-glucose glycoconjugates during Maillard reaction (MR) has been studied, respectively, in basic and neutral media. As compared to equivalent conventional heat treatments, a higher formation of furosine, as indicator of initial steps of MR, was observed together with more advance of the reaction in US treated samples, this effect being more pronounced with the increase of US amplitude (50-70%) and temperature (25-40 °C). Regarding the influence of US on lactulose formation, in general, in a buffered system (pH 10.0), US at 70% of amplitude and 60 °C increased the rate of lactose isomerization, higher values of lactulose, epilactose and galactose being observed in comparison to conventional heating. The results of this work showed an acceleration of both reactions by US, indicating its usefulness to promote the formation of functional ingredients.

  11. The impact of the Maillard reaction on the in vitro proteolytic breakdown of bovine lactoferrin in adults and infants.

    Science.gov (United States)

    Moscovici, Alice M; Joubran, Yousef; Briard-Bion, Valerie; Mackie, Alan; Dupont, Didier; Lesmes, Uri

    2014-08-01

    The Maillard reaction has been proposed as a natural pathway to functionalize proteins and modulate their proteolysis. Nevertheless, gaps in understanding the digestive fate of Maillard reaction products (MRPs) still exist, especially regarding bioactive proteins such as lactoferrin (LF). UV absorbance and SDS-PAGE were used to monitor reaction progression under mild thermal processing (60 °C, 79% RH). Dynamic light scattering showed that MRPs had increased colloidal size and turbidity at 3 < pH < 10. FRAP analysis and in vitro digestion experiments demonstrated that MRPs possessed improved antioxidant capacity and higher susceptibility to proteolysis to varying extents under adult conditions compared to infant conditions. Proteomic analyses of MRP digesta revealed altered enzymatic cleavage patterns with no pronounced changes in the formation of known bioactive peptides. These also indicated that MRPs may breakdown in the gastro-intestinal tract to potentially form novel bioactive peptides. Overall, this work highlights that the Maillard reaction could be harnessed to modify the extent of proteolysis and bioactivity of proteins.

  12. Assessment of the ribose-induced Maillard reaction as a means of gelatine powder identification and quality control.

    Science.gov (United States)

    Tan, Thuan-Chew; AlKarkhi, Abbas F M; Easa, Azhar Mat

    2012-10-15

    The addition of ribose to bovine or porcine gelatine solutions followed by heating at 95 °C yielded brown solutions with different pH, colour (CIE L(*) and b(*)) and absorbance (A(420*) values. These differences were used for gelatine powder identification, differentiation and quality control. Differentiation analysis of the Maillard reaction parameters was conducted using cluster analysis (CA) and confidence intervals (CI). The potential use of the method as a quality control procedure was evaluated by using statistical process control (SPC). CA revealed that the two types of gelatine could be classified into two different groups. CI (95% confidence) revealed that the absorbance and colour values could be used as indicators for differentiation between the two types of gelatine because the intervals between the Maillard reaction parameters of the samples were far apart. The methodology demonstrated good reproducibility because it behaved predictably based on the X¯-S charts generated from the SPC charts.

  13. High-intensity ultrasound production of Maillard reaction flavor compounds in a cysteine-xylose model system.

    Science.gov (United States)

    Ong, Olivia X H; Seow, Yi-Xin; Ong, Peter K C; Zhou, Weibiao

    2015-09-01

    Application of high intensity ultrasound has shown potential in the production of Maillard reaction odor-active flavor compounds in model systems. The impact of initial pH, sonication duration, and ultrasound intensity on the production of Maillard reaction products (MRPs) by ultrasound processing in a cysteine-xylose model system were evaluated using Response Surface Methodology (RSM) with a modified mathematical model. Generation of selected MRPs, 2-methylthiophene and tetramethyl pyrazine, was optimal at an initial pH of 6.00, accompanied with 78.1 min of processing at an ultrasound intensity of 19.8 W cm(-2). However, identification of volatiles using gas chromatography-mass spectrometry (GC/MS) revealed that ultrasound-assisted Maillard reactions generated fewer sulfur-containing volatile flavor compounds as compared to conventional heat treatment of the model system. Likely reasons for this difference in flavor profile include the expulsion of H2S due to ultrasonic degassing and inefficient transmission of ultrasonic energy. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Maillard reaction products in bread: A novel semi-quantitative method for evaluating melanoidins in bread.

    Science.gov (United States)

    Helou, Cynthia; Jacolot, Philippe; Niquet-Léridon, Céline; Gadonna-Widehem, Pascale; Tessier, Frédéric J

    2016-01-01

    The aim of this study was to test the methods currently in use and to develop a new protocol for the evaluation of melanoidins in bread. Markers of the early and advanced stages of the Maillard reaction were also followed in the crumb and the crust of bread throughout baking, and in a crust model system. The crumb of the bread contained N(ε)-fructoselysine and N(ε)-carboxymethyllysine but at levels 7 and 5 times lower than the crust, respectively. 5-Hydroxymethylfurfural was detected only in the crust and its model system. The available methods for the semi-quantification of melanoidins were found to be unsuitable for their analysis in bread. Our new method based on size exclusion chromatography and fluorescence measures soluble fluorescent melanoidins in bread. These melanoidin macromolecules (1.7-5.6 kDa) were detected intact in both crust and model system. They appear to contribute to the dietary fibre in bread. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Temperature effect on lactose crystallization, maillard reactions, and lipid oxidation in whole milk powder.

    Science.gov (United States)

    Thomsen, Marianne K; Lauridsen, Lene; Skibsted, Leif H; Risbo, Jens

    2005-09-07

    Whole milk powder with an initial water content of 4.4% (w/w) and a water activity of 0.23 stored in hermetically sealed vials for up to 147 days below (37 and 45 degrees C) and above (55 degrees C) the glass transition temperature (T(g) determined to have the value 48 degrees C) showed a strong temperature dependence for quality deterioration corresponding to energies of activation close to 200 kJ/mol for most deteriorative processes. The glass transition was found not to cause any deviation from Arrhenius temperature dependence. Lactose crystallization, which occurred as a gradual process as monitored by isothermal calorimetry, is concluded to liberate bound water (a(w) increase to 0.46) with a modest time delay (approximately 2 days at 55 degrees C) and with concomitant surface browning as evidenced by an increasing Hunter b-value. Browning and formation of bound hydroxymethyl-furfural determined by HPLC seem to be coupled, while formation of another Maillard reaction product, furosine, occurred gradually and was initiated prior to crystallization. Initiation of lipid oxidation, as detected by lipid-derived radicals (high g-value ESR spectra), and progression of lipid oxidation, as detected by headspace GC, seem not to be affected by lactose crystallization and browning, and no indication of browning products acting as antioxidants could be determined.

  16. Detection of Maillard reaction products by a coupled HPLC-Fraction collector technique and FTIR characterization of Cu(II)-complexation with the isolated species

    Science.gov (United States)

    Ioannou, Aristos; Daskalakis, Vangelis; Varotsis, Constantinos

    2017-08-01

    The isolation of reaction products of asparagine with reducing sugars at alkaline pH and high temperature has been probed by a combination of high performance liquid chromatography (HPLC) coupled with a Fraction Collector. The UV-vis and FTIR spectra of the isolated Maillard reaction products showed structure-sensitive changes as depicted by deamination events and formation of asparagine-saccharide conjugates. The initial reaction species of the Asn-Gluc reaction were also characterized by Density Functional Theory (DFT) methods. Evidence for Cu (II) metal ion complexation with the Maillard reaction products is supported by UV-vis and FTIR spectroscopy.

  17. Predictive Modeling of Flavor Compound Formation in the Maillard Reaction: A SWOT Analysis

    NARCIS (Netherlands)

    Boekel, van M.A.J.S.

    2010-01-01

    The importance of Maillard flavor compounds for food quality is undisputed, but we are far from being able to control such formation quantitatively in food processing. Kinetic models attempt to predict rates of formation as a function of temperature, pH, water activity/content, and chemical reactivi

  18. Predictive Modeling of Flavor Compound Formation in the Maillard Reaction: A SWOT Analysis

    NARCIS (Netherlands)

    Boekel, van M.A.J.S.

    2010-01-01

    The importance of Maillard flavor compounds for food quality is undisputed, but we are far from being able to control such formation quantitatively in food processing. Kinetic models attempt to predict rates of formation as a function of temperature, pH, water activity/content, and chemical

  19. Short communication: Amino trap column improves the separation of methylimidazoles, 5-hydroxymethyl-2-furaldehyde, and sugars in Maillard reaction.

    Science.gov (United States)

    Xu, Xian-Bing; Liu, Ding-Bo; Yu, Shu-Juan; Zhao, Zhen-Gang; Yu, Pei

    2014-11-01

    A simultaneous analysis of methylimidazoles, reducing sugars, and 5-hydroxymethyl-2-furaldehyde in the Maillard reaction was improved by use of an amino trap column. Analysis was carried out by using high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) coupled with an amino trap column. The amino trap column was a useful tool to improve the separation of methylimidazoles, reducing sugars, and 5-hydroxymethyl-2-furaldehyde. This technique is useful for simultaneous analysis of methylimidazoles, reducing sugars, and 5-hydroxymethyl-2-furaldehyde in risk assessment for dairy products.

  20. A Perspective on the Maillard Reaction and the Analysis of Protein Glycation by Mass Spectrometry: Probing the Pathogenesis of Chronic Disease

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qibin; Ames, Jennifer M.; Smith, Richard D.; Baynes, John; Metz, Thomas O.

    2008-12-18

    The Maillard reaction, starting from the glycation of protein and progressing to the formation of advanced glycation end-products (AGEs), is implicated in the development of complications of diabetes mellitus, as well as in the pathogenesis of cardiovascular, renal, and neurodegenerative diseases. In this perspective review, we provide on overview on the relevance of the Maillard reaction in the pathogenesis of chronic disease and discuss traditional approaches and recent developments in the analysis of glycated proteins by mass spectrometry. We propose that proteomics approaches, particularly bottom-up proteomics, will play a significant role in analyses of clinical samples leading to the identification of new markers of disease development and progression.

  1. Evolution of protein bound Maillard reaction end-products and free Amadori compounds in low lactose milk in presence of fructosamine oxidase i

    NARCIS (Netherlands)

    Troise, Antonio Dario; Buonanno, Martina; Fiore, Alberto; Monti, Simona Maria; Fogliano, Vincenzo

    2016-01-01

    Thermal treatments and storage influence milk quality, particularly in low lactose milk as the higher concentration of reducing sugars can lead to the increased formation of the Maillard reaction products (MRPs). The control of the Amadori products (APs) formation is the key step to mitigate the

  2. Evolution of protein bound Maillard reaction end-products and free Amadori compounds in low lactose milk in presence of fructosamine oxidase i

    NARCIS (Netherlands)

    Troise, Antonio Dario; Buonanno, Martina; Fiore, Alberto; Monti, Simona Maria; Fogliano, Vincenzo

    2016-01-01

    Thermal treatments and storage influence milk quality, particularly in low lactose milk as the higher concentration of reducing sugars can lead to the increased formation of the Maillard reaction products (MRPs). The control of the Amadori products (APs) formation is the key step to mitigate the

  3. Effect of Maillard reaction on biochemical properties of peanut 7S globulin (Ara h 1) and its interaction with a human colon cancer cell line (Caco-2)

    NARCIS (Netherlands)

    Teodorowicz, M.; Fiedorowicz, E.; Kostyra, H.; Wichers, H.J.; Kostyra, E.

    2013-01-01

    Purpose The purpose of this study was to determine the influence of Maillard reaction (MR, glycation) on biochemical and biological properties of the major peanut allergen Ara h 1. Methods Three different time/temperature conditions of treatment were applied (37, 60, and 145 °C). The extent of MR wa

  4. Effect of Maillard reaction on biochemical properties of peanut 7S globulin (Ara h 1) and its interaction with a human colon cancer cell line (Caco-2)

    NARCIS (Netherlands)

    Teodorowicz, M.; Fiedorowicz, E.; Kostyra, H.; Wichers, H.J.; Kostyra, E.

    2013-01-01

    Purpose The purpose of this study was to determine the influence of Maillard reaction (MR, glycation) on biochemical and biological properties of the major peanut allergen Ara h 1. Methods Three different time/temperature conditions of treatment were applied (37, 60, and 145 °C). The extent of MR wa

  5. Free and Protein-Bound Maillard Reaction Products in Beer: Method Development and a Survey of Different Beer Types.

    Science.gov (United States)

    Hellwig, Michael; Witte, Sophia; Henle, Thomas

    2016-09-28

    The Maillard reaction is important for beer color and flavor, but little is known about the occurrence of individual glycated amino acids in beer. Therefore, seven Maillard reaction products (MRPs), namely, fructosyllysine, maltulosyllysine, pyrraline, formyline, maltosine, MG-H1, and argpyrimidine, were synthesized and quantitated in different types of beer (Pilsner, dark, bock, wheat, and nonalcoholic beers) by HPLC-ESI-MS/MS in the multiple reaction monitoring mode through application of the standard addition method. Free MRPs were analyzed directly. A high molecular weight fraction was isolated by dialysis and hydrolyzed enzymatically prior to analysis. Maltulosyllysine was quantitated for the first time in food. The most important free MRPs in beer are fructosyllysine (6.8-27.0 mg/L) and maltulosyllysine (3.7-21.8 mg/L). Beer contains comparatively high amounts of late-stage free MRPs such as pyrraline (0.2-1.6 mg/L) and MG-H1 (0.3-2.5 mg/L). Minor amounts of formyline (4-230 μg/L), maltosine (6-56 μg/L), and argpyrimidine (0.1-4.1 μg/L) were quantitated. Maltulosyllysine was the most significant protein-bound MRP, but both maltulosyllysine and fructosyllysine represent only 15-60% of the total protein-bound lysine-derived Amadori products. Differences in the patterns of protein-bound and free individual MRPs and the ratios between them were identified, which indicate differences in their chemical, biochemical, and microbiological stabilities during the brewing process.

  6. Antioxidant and antimicrobial activity of Maillard reaction products from xylan with chitosan/chitooligomer/glucosamine hydrochloride/taurine model systems.

    Science.gov (United States)

    Wu, Shuping; Hu, Jiao; Wei, Liuting; Du, Yumin; Shi, Xiaowen; Zhang, Lina

    2014-04-01

    The structure, UV absorbance, browning intensity, fluorescence changes, antioxidant activity and antimicrobial assessment of Maillard reaction products (MRPs) derived from xylan with chitosan, chitooligomer, glucosamine hydrochloride and taurine model systems were evaluated. The results revealed that all MRPs had similar infrared spectra and molecular structures. MRPs from different model systems on the UV absorbance at 294 nm after heated 90 min and browning intensity at 420 nm showed the similar law: xylan-taurine > xylan-glucosamine hydrochloride > xylan-chitooligomer > xylan-chitosan, and the order of DPPH scavenging activity of MRPs was as follows: xylan-chitosan > xylan-chitooligomer > xylan-glucosamine hydrochloride > xylan-taurine, which revealed that the properties of MRPs were closely related to molecular weight of model systems. Moreover, the highest radical scavenging activity of MRPs from xylan with chitosan/chitooligomer/glucosamine hydrochloride/taurine model systems was 65.9%, 63.7%, 46.4% and 42.5%, respectively.

  7. Effect of roasting time of buckwheat groats on the formation of Maillard reaction products and antioxidant capacity.

    Science.gov (United States)

    Małgorzata, Wronkowska; Konrad, Piskuła Mariusz; Zieliński, Henryk

    2016-04-01

    Changes in the formation of Maillard reaction products and antioxidant capacity of buckwheat, induced by roasting at 160 °C for 30, 40 and 50 min, were evaluated in the study. Furozine, was detected after roasting, in all buckwheat samples. Increase of FIC, the presence of significant amounts of CML and enhanced browning were observed, along with increasing times of roasting. The formation of acrylamide in the obtained buckwheat products was also significantly connected with the time of roasting. A significant degradation was observed in natural antioxidants, as affected by heat treatment time. The colour parameter changed significantly with the increasing of roasting time. Overall, 30min of roasting was beneficial from a nutritional point of view for the obtained buckwheat product.

  8. Antioxidative, Antibacterial, and Food Functional Properties of the Half-Fin Anchovy Hydrolysates-Glucose Conjugates Formed via Maillard Reaction

    Directory of Open Access Journals (Sweden)

    Ru Song

    2016-06-01

    Full Text Available The antioxidative, antibacterial, and food functional properties of the half-fin anchovy hydrolysates (HAHp-glucose conjugates formed by Maillard reaction (MR were investigated, respectively. Results of sugar and amino acid contents loss rates, browning index, and molecular weight distribution indicated that the initial pH of HAHp played an important role in the process of MR between HAHp and glucose. HAHp-glucose Maillard reaction products (HAHp-G MRPs demonstrated enhanced antioxidative activities of reducing power and scavenging DPPH radicals compared to control groups. HAHp-G MRPs produced from the condition of pH 9.6 displayed the strongest reducing power. The excellent scavenging activity on DPPH radicals was found for HAHp(5.6-G MRPs which was produced at pH 5.6. Additionally, HAHp(5.6-G MRPs showed variable antibacterial activities against Escherichia coli, Pseudomonas fluorescens, Proteus vulgaris, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Bacillus megaterium, and Sarcina lutea, with the MIC values ranging from 8.3 to 16.7 μg/mL. Result of scanning electron microscopy (SEM on E. coli suggested that HAHp(5.6-G MRPs exhibited antibacterial activity by destroying the cell integrity through membrane permeabilization. Moreover, HAHp(5.6-G MRPs had excellent foaming ability and stability at alkaline conditions of pH 8.0, and showed emulsion properties at acidic pH 4.0. These results suggested that specific HAHp-G MRPs should be promising functional ingredients used in foods.

  9. Antioxidative, Antibacterial, and Food Functional Properties of the Half-Fin Anchovy Hydrolysates-Glucose Conjugates Formed via Maillard Reaction.

    Science.gov (United States)

    Song, Ru; Yang, Peiyu; Wei, Rongbian; Ruan, Guanqiang

    2016-06-20

    The antioxidative, antibacterial, and food functional properties of the half-fin anchovy hydrolysates (HAHp)-glucose conjugates formed by Maillard reaction (MR) were investigated, respectively. Results of sugar and amino acid contents loss rates, browning index, and molecular weight distribution indicated that the initial pH of HAHp played an important role in the process of MR between HAHp and glucose. HAHp-glucose Maillard reaction products (HAHp-G MRPs) demonstrated enhanced antioxidative activities of reducing power and scavenging DPPH radicals compared to control groups. HAHp-G MRPs produced from the condition of pH 9.6 displayed the strongest reducing power. The excellent scavenging activity on DPPH radicals was found for HAHp(5.6)-G MRPs which was produced at pH 5.6. Additionally, HAHp(5.6)-G MRPs showed variable antibacterial activities against Escherichia coli, Pseudomonas fluorescens, Proteus vulgaris, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Bacillus megaterium, and Sarcina lutea, with the MIC values ranging from 8.3 to 16.7 μg/mL. Result of scanning electron microscopy (SEM) on E. coli suggested that HAHp(5.6)-G MRPs exhibited antibacterial activity by destroying the cell integrity through membrane permeabilization. Moreover, HAHp(5.6)-G MRPs had excellent foaming ability and stability at alkaline conditions of pH 8.0, and showed emulsion properties at acidic pH 4.0. These results suggested that specific HAHp-G MRPs should be promising functional ingredients used in foods.

  10. The Maillard reaction of a shrimp by-product protein hydrolysate: chemical changes and inhibiting effects of reactive oxygen species in human HepG2 cells.

    Science.gov (United States)

    Zha, Fengchao; Wei, Binbin; Chen, Shengjun; Dong, Shiyuan; Zeng, Mingyong; Liu, Zunying

    2015-06-01

    Recently, much attention has been given to improving the antioxidant activity of protein hydrolysates via the Maillard reaction, but little is known about the cellular antioxidant activity of Maillard reaction products (MRPs) from protein hydrolysates. We first investigated chemical characterization and the cellular antioxidant activity of MRPs in a shrimp (Litopenaeus vannamei) by-product protein hydrolysate (SBH)-glucose system at 110 °C for up to 10 h of heating. Solutions of SBH and glucose were also heated alone as controls. The Maillard reaction greatly resulted in the increase of hydroxymethylfurfural (HMF) and browning intensity, high molecular weight fraction, and reduction of the total amino acid in SBH with the heating time, which correlated well with the free radical scavenging activity of MRPs. MRPs had stronger inhibiting effects on oxidative stress of human HepG2 cells than the original SBH, and its cellular antioxidant activity strongly correlated with free radical scavenging activity, but less affected by the browning intensity and HMF level. The caramelization of glucose partially affected the HMF level and free radical scavenging activity of MRPs, but it was not related to the cellular antioxidant activity. The cellular antioxidant activity of MRPs for 5 h of heating time appeared to reach a maximum level, which was mainly due to carbonyl ammonia condensation reaction. In conclusion, the Maillard reaction is a potential method to increase the cellular antioxidant activity of a shrimp by-product protein hydrolysate, but the higher HMF levels and the lower amino acid content in MRPs should also be considered.

  11. A Perspective on the Maillard Reaction and the Analysis of Protein Glycation by Mass Spectrometry: Probing the Pathogenesis of Chronic Disease

    Science.gov (United States)

    Zhang, Qibin; Ames, Jennifer M.; Smith, Richard D.; Baynes, John W.; Metz, Thomas O.

    2009-01-01

    The Maillard reaction, starting from the glycation of protein and progressing to the formation of advanced glycation end-products (AGEs), is implicated in the development of complications of diabetes mellitus, as well as in the pathogenesis of cardiovascular, renal, and neurodegenerative diseases. In this perspective review, we provide an overview on the relevance of the Maillard reaction in the pathogenesis of chronic disease and discuss traditional approaches and recent developments in the analysis of glycated proteins by mass spectrometry. We propose that proteomics approaches, particularly bottom-up proteomics, will play a significant role in analyses of clinical samples leading to the identification of new markers of disease development and progression. PMID:19093874

  12. Evolution of protein bound Maillard reaction end-products and free Amadori compounds in low lactose milk in presence of fructosamine oxidase I.

    Science.gov (United States)

    Troise, Antonio Dario; Buonanno, Martina; Fiore, Alberto; Monti, Simona Maria; Fogliano, Vincenzo

    2016-12-01

    Thermal treatments and storage influence milk quality, particularly in low lactose milk as the higher concentration of reducing sugars can lead to the increased formation of the Maillard reaction products (MRPs). The control of the Amadori products (APs) formation is the key step to mitigate the Maillard reaction (MR) in milk. The use of fructosamine oxidases, (Faox) provided promising results. In this paper, the effects of Faox I were evaluated by monitoring the concentration of free and bound MRPs in low lactose milk during shelf life. Results showed that the enzyme reduced the formation of protein-bound MRPs down to 79% after six days at 37°C. Faox I lowered the glycation of almost all the free amino acids resulting effective on basic and polar amino acids. Data here reported corroborate previous findings on the potentiality of Faox enzymes in controlling the early stage of the MR in foods.

  13. Prenatal dietary load of Maillard reaction products combined with postnatal Coca-Cola drinking affects metabolic status of female Wistar rats

    OpenAIRE

    Gurecká, Radana; Koborová, Ivana; Janšáková, Katarína; Tábi, Tamás; Szökő, Éva; Somoza, Veronika; Šebeková, Katarína; Celec, Peter

    2015-01-01

    Aim To assess the impact of prenatal exposure to Maillard reaction products (MRPs) -rich diet and postnatal Coca- Cola consumption on metabolic status of female rats. Diet rich in MRPs and consumption of saccharose/fructose sweetened soft drinks is presumed to impose increased risk of development of cardiometabolic afflictions, such as obesity or insulin resistance. Methods At the first day of pregnancy, 9 female Wistar rats were randomized into two groups, pair-fed ei...

  14. Effects of Temperatures on Maillard Reactions%温度对美拉德反应的研究

    Institute of Scientific and Technical Information of China (English)

    吴少雄; M A J S van Boeke; S I F S Martins; 郭祀远; 李琳

    2005-01-01

    The effects of temperatures on the development of the Maillard reaction in aqueous model systems containing glucose and glycine heat treated for different times at three temperatures respectively (80℃, 100℃ and 120℃) were studied. In particular, an investigation was carried out into the different temperatures used on the degradation of sugars and amino acid and the extent of accumulation of browning intermediates, such as Amadori product, organic acid, brown pigment formation and pH changes. Results showed that, with increasing temperature and time the rate of reactions rose.%本文报道了反应温度对以d-葡萄糖和1-甘氨酸水溶液模式体系美拉德反应的影响.研究了在不同反应温度(80、100、120℃)和不同反应时间下,体系中糖和氨基酸的降解程度,反应中间体:阿利德诺和有机酸的累积程度,类黑素的形成及pH变化程度.研究结果表明:随着反应温度和反应时间的增加,反应速率加快.

  15. Role of the Maillard reaction in aging of tissue proteins. Advanced glycation end product-dependent increase in imidazolium cross-links in human lens proteins.

    Science.gov (United States)

    Frye, E B; Degenhardt, T P; Thorpe, S R; Baynes, J W

    1998-07-24

    Dicarbonyl compounds such as glyoxal and methylglyoxal are reactive dicarbonyl intermediates in the nonenzymatic browning and cross-linking of proteins during the Maillard reaction. We describe here the quantification of glyoxal and methylglyoxal-derived imidazolium cross-links in tissue proteins. The imidazolium salt cross-links, glyoxal-lysine dimer (GOLD) and methylglyoxal-lysine dimer (MOLD), were measured by liquid chromatography/mass spectrometry and were present in lens protein at concentrations of 0. 02-0.2 and 0.1-0.8 mmol/mol of lysine, respectively. The lens concentrations of GOLD and MOLD correlated significantly with one another and also increased with lens age. GOLD and MOLD were present at significantly higher concentrations than the fluorescent cross-links pentosidine and dityrosine, identifying them as major Maillard reaction cross-links in lens proteins. Like the N-carboxy-alkyllysines Nepsilon-(carboxymethyl)lysine and Nepsilon-(carboxyethyl)lysine, these cross-links were also detected at lower concentrations in human skin collagen and increased with age in collagen. The presence of GOLD and MOLD in tissue proteins implicates methylglyoxal and glyoxal, either free or protein-bound, as important precursors of protein cross-links formed during Maillard reactions in vivo during aging and in disease.

  16. Application of Maillard reaction products in tobacco industry%美拉德反应产物在烟草工业中的应用

    Institute of Scientific and Technical Information of China (English)

    程传玲; 杨艳勤; 刘仕民; 宋辉; 李瑞丽; 杨若嵩

    2014-01-01

    综述了美拉德反应产物在卷烟加香、烟草薄片、烟草生物技术等方面的应用,指出:应提高美拉德反应产物的质量,开发出色泽与烟叶颜色相近,香味与天然烟香接近,而且在抽吸时能裂解成与烟香谐调的香味物质,既能掩盖杂气,又能使人抽吸时感到愉快的、能替代尼古丁的、无害的美拉德反应产物。%The application of Maillard reaction products in tobacco flavoring,tobacco sheet,tobacco biologi-cal technology etc.were reviewed.It was pointed out:the quality of Maillard reaction products should be improved,flavor substance should be developed similar to leaf color,fragrance and natural aroma,cracking and flavor aroma of coordination in the suction,which could cover the miscellaneous gas,and make people feel happy in aspiration in order to produce nicotine,replacing harmless Maillard reaction products.

  17. Study on Sensory Quality, Antioxidant Properties, and Maillard Reaction Products Formation in Rye-Buckwheat Cakes Enhanced with Selected Spices

    Directory of Open Access Journals (Sweden)

    Małgorzata Przygodzka

    2015-01-01

    Full Text Available The effect of selected spices included in the recipe of rye-buckwheat cakes on sensory quality, nutritional value, and Maillard reaction (MR products formation was addressed in this study. The cakes with cloves, nutmeg, allspice, cinnamon, vanilla, and spice mix addition revealed the highest overall quality values. Cakes enriched with cloves, allspice, and spice mix showed the highest rutin content and almost threefold higher available lysine contents whereas cakes enhanced with mix, cloves, and cinnamon were the richest source of phenolic compounds. The highest antioxidant capacity showed cakes with cloves and spice mix. The furosine, a marker of early stage of MR, was decreased in cakes with cloves, allspice, spice mix, and vanilla whereas fluorescent intermediatory compounds were reduced in cakes enhanced with cloves, allspice, and cinnamon. In contrast, browning index was increased as compared to cakes without spices. The FAST index was significantly lowered in all cakes enriched with spices, especially with cloves, allspice, and mix addition. The presence of cloves, allspice, and vanilla in cake formula was the most efficient in acrylamide strategy. It can be suggested that cloves, allspice, and vanilla might be used for production of safety and good quality cakes.

  18. Electro-activation of sweet defatted whey: Impact on the induced Maillard reaction products and bioactive peptides.

    Science.gov (United States)

    Kareb, Ourdia; Gomaa, Ahmed; Champagne, Claude P; Jean, Julie; Aïder, Mohammed

    2017-04-15

    Electro-activation was used to add value to sweet defatted whey. This study aimed to investigate and to characterize the bioactive compounds formed under different electro-activation conditions by molecular and proteomic approaches. The effects of electric current intensity (400, 500 or 600mA) and whey concentration (7, 14 or 21% (w/v)) as a function of the electro-activation time (0, 15, 30 or 45min) were evaluated. The targeted dependent variables were the formation of Maillard reaction products (MRPs), protein hydrolysates and glycated compounds. It was shown that the MRPs derived from electro-activated whey at a concentration of 14% had the highest potential of biological activity. SDS-PAGE analyses indicated the formation of hydrolysates and glycated compounds with different molecular weight distributions. FTIR indicated the predominance of intermediate MRPs, such as the Schiff base compounds. LC-MS/MS and proteomics analysis showed the production of multi-functional bioactive peptides due to the hydrolysis of whey proteins.

  19. Short communication: Hypolipidemic and antiinflammatory effects of fermented Maillard reaction products by Lactobacillus fermentum H9 in an animal model.

    Science.gov (United States)

    Oh, Nam Su; Koh, Ji Hoon; Park, Mi Ri; Kim, Younghoon; Kim, Sae Hun

    2016-12-01

    This study examined the effects of Maillard reaction products reacted by casein and lactose (cMRP) and of cMRP fermented by Lactobacillus fermentum H9 (F-cMRP) on hypolipidemic and antiinflammatory effects in rats fed a high-fat and high-cholesterol diet (HD). The HD-fed rats had significantly increased hepatic triglyceride concentrations compared with the rats fed a normal diet. It was shown that treatment with simvastatin, L. fermentum H9 (H9), cMRP, and F-cMRP decreased total triglycerides in the liver compared with the HD group. On histological analysis, a reduction of lipid accumulation in the liver and aortic tissues was observed in the cMRP, F-cMRP, and H9-fed rats. Also, F-cMRP and cMRP reduced intima-media thickness in the HD group. In addition, the H9, cMRP, and F-cMRP treatments significantly reduced the expression levels of ICAM-1 and VCAM-1, but not of MCP-1. In particular, the expressions of ICAM-1 and VCAM-1 were significantly decreased in the F-cMRP group compared with the HD group. These results of the present study suggest that cMRP and F-cMRP in dairy foods could potentially be used to prevent or treat cardiovascular diseases, especially atherosclerosis. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  20. Maillard reactions and increased enzyme inactivation during oligosaccharide synthesis by a hyperthermophilic glycosidase

    NARCIS (Netherlands)

    Bruins, M.E.; Hellemond, van E.W.; Janssen, A.E.M.; Boom, R.M.

    2003-01-01

    The thermostable Pyrococcus furiosus beta-glycosidase was used for oligosaccharide production from lactose in a kinetically controlled reaction. Our experiments showed that higher temperatures are beneficial for the absolute as well as relative oligosaccharide yield. However, at reaction

  1. Functional improvements in bovine serum albumin-fucoidan conjugate through the Maillard reaction.

    Science.gov (United States)

    Kim, Do-Yeong; Shin, Weon-Sun

    2016-01-01

    The solubility, thermal stability, surface activity and emulsifying properties of native bovine serum albumin (BSA), heat-treated BSA, a BSA-fucoidan mixture, and a BSA-fucoidan conjugate were assessed. Covalent linkage of BSA with fucoidan resulted in significantly (p fucoidan conjugate had a high melting temperature (97.09 ± 1.45 °C), as found by differential scanning calorimetry, indicating strong heat stability and high resistance to denaturation. Although the attachment of fucoidan, a non-surface-active hydrophilic polysaccharide, gave no change in the surface activity, the emulsifying activity and the emulsion stability of the conjugate at pH 5 were superior to those of native BSA, heat-treated BSA, and the BSA-fucoidan mixture. Conclusively, fucoidan attachment enhanced the solubility, thermal stability and emulsifying properties of the protein molecules with negative charge distribution and steric stabilization.

  2. Effects of o-phenylenediamine on methylglyoxal generation from monosaccharide: Comment on "correlation of methylglyoxal with acrylamide formation in fructose/asparagine Maillard reaction model system".

    Science.gov (United States)

    Wang, Yu; Ho, Chi-Tang

    2008-07-01

    Methylglyoxal (MG), a reactive carbonyl compound, has recently garnered much attention because of its ability to modify proteins over time and yield advanced glycation end products (AGEs) that are thought to contribute to the development of diabetes mellitus and its complications. In a recent paper published in Food Chemistry by Yuan et al. [Yuan, Y., Zhao, G. H., Hu, X. S., Wu, J. H., Liu, J., & Chen, F. (2007a). Correlation of methylglyoxal with acrylamide formation in fructose/asparagines Maillard reaction model system. Food Chemistry, 108(3), 885-890] authors showed a high correlation between methylglyoxal formation and acrylamide formation. However, in their study, model systems of aqueous fructose/asparagines (Fru/Asn) and fructose/asparagines/o-phenylenediamine (Fru/Asn/OPD) heating at 150°C were used. The validity of these models relies on the assumption that OPD will only serve the role of a trapping agent for MG. In this short communication, we would like to call to attention that MG can also have a strong catalytic effect in the generation of MG from fructose. Therefore, it is concluded that the concentration of MG obtained in Fru/Asn/OPD model system cannot correspond to the total amount of MG formed by Maillard reaction of Fru and Asn as claimed by Yuan et al. [Yuan, Y., Zhao, G. H., Hu, X. S., Wu, J. H., Liu, J., & Chen, F. (2007a). Correlation of methylglyoxal with acrylamide formation in fructose/asparagines Maillard reaction model system. Food Chemistry, 108(3), 885-890, Yuan, Y., Zhao, G. H., Hu X. S., Wu, J. H., Liu, J., & Chen. F. (2007b). High correlation of methylglyoxal with acrylamide formation in glucose/asparagine Maillardreaction model. European Food Research and Technology. doi:10.1007/s00217-007-0658-0].

  3. Temperature Influence on Acetyllysine Interaction with Glucose in Model Systems due to Maillard Reaction

    Science.gov (United States)

    1992-01-01

    Loncin noodles of 15.2 ± 9.1 and in pasta of 12.8 ± 5.2 kcal/mol Kaet at., 1986 anLove, 1988;Labuz and Satmarch , 19 ; nhave been reported at a, 0.44...glucose model were cons~derably lower dental (Glasstone, 1961). Further, a bimolecular reaction is than those observed for the lysine-glucose model (5.0 x...the a,,. pasta , fish flour, egg noodles, and fortified rice meal respec- tively). The low E, values in the range 5-13 kcal/mol for fish flour stored in

  4. Impact of thermal processing and the Maillard reaction on the basophil activation of hazelnut allergic patients.

    Science.gov (United States)

    Cucu, Tatiana; De Meulenaer, Bruno; Bridts, Chris; Devreese, Bart; Ebo, Didier

    2012-05-01

    Food allergy, an abnormal immunological response due to sensitization to a food component, has become an important health problem, especially in industrialized countries. The aim of this study was to investigate the impact of thermal processing and glycation on the basophil activation by hazelnut proteins using a basophil activation test. Patients with systemic allergic reactions (SR; n=6) to hazelnut as well as patients with an isolated oral allergy syndrome (OAS; n=4) were investigated. Thermal processing of hazelnut proteins either in the presence or absence of wheat proteins did not result in major changes in the stimulatory activity of the basophils for patients with SR or OAS. For the patients with OAS, incubation of hazelnut proteins with glucose led to complete depletion of the stimulatory activity of the basophils. An increase in stimulatory activity of the basophils for two out of six patients with SR was observed. For the other four patients slight or complete abolition of the stimulatory activity was observed. These results indicate that some patients with SR to hazelnut are at risk when exposed to hazelnut proteins, even in processed foods.

  5. Aldimine Formation Reaction, the First Step of the Maillard Early-phase Reaction, Might be Enhanced in Variant Hemoglobin, Hb Himeji.

    Science.gov (United States)

    Koga, Masafumi; Inada, Shinya; Shimizu, Sayoko; Hatazaki, Masahiro; Umayahara, Yutaka; Nishihara, Eijun

    2015-01-01

    Hb Himeji (β140Ala→Asp) is known as a variant hemoglobin in which glycation is enhanced and HbA1c measured by immunoassay shows a high value. The phenomenon of enhanced glycation in Hb Himeji is based on the fact that the glycation product of variant hemoglobin (HbX1c) shows a higher value than HbA1c. In this study, we investigated whether aldimine formation reaction, the first step of the Maillard early-phase reaction, is enhanced in Hb Himeji in vitro. Three non-diabetic subjects with Hb Himeji and four non-diabetic subjects without variant hemoglobin were enrolled. In order to examine aldimine formation reaction, whole blood cells were incubated with 500 mg/dl of glucose at 37°C for 1 hour and were analyzed by high-performance liquid chromatography. Both HbA1c and HbX1c were not increased in this condition. After incubation with glucose, labile HbA1c (LA1c) fraction increased in the controls (1.1±0.3%). In subjects with Hb Himeji increases in the labile HbX1c (LX1c) fraction as well as the LA1c fraction were observed, and the degree of increase in the LX1c fraction was significantly higher than that of the LA1c fraction (1.8±0.1% vs. 0.5±0.2%, PHb Himeji in vitro. The 140th amino acid in β chain of hemoglobin is suggested to be involved in aldimine formation reaction.

  6. Flows and chemical reactions in heterogeneous mixtures

    CERN Document Server

    Prud'homme, Roger

    2014-01-01

    This book - a sequel of previous publications 'Flows and Chemical Reactions' and 'Chemical Reactions in Flows and Homogeneous Mixtures' - is devoted to flows with chemical reactions in heterogeneous environments.  Heterogeneous media in this volume include interfaces and lines. They may be the site of radiation. Each type of flow is the subject of a chapter in this volume. We consider first, in Chapter 1, the question of the generation of environments biphasic individuals: dusty gas, mist, bubble flow.  Chapter 2 is devoted to the study at the mesoscopic scale: particle-fluid exchange of mom

  7. Low intramuscular fat (but high in PUFA) content in cooked cured pork ham decreased Maillard reaction volatiles and pleasing aroma attributes.

    Science.gov (United States)

    Benet, Iu; Guàrdia, Maria Dolors; Ibañez, Carles; Solà, Josep; Arnau, Jacint; Roura, Eugeni

    2016-04-01

    The influence of intramuscular fat content (high - HI versus low - LI) and fatty acid composition on pork cooked cured ham flavour was analysed by gas chromatography-olfactometry using nasal impact frequency (GC-O/NIF) and quantitative descriptive analysis (QDA). Potential relationships were studied by principal component analysis (PCA). Sixteen and fourteen odourants were identified by GC-O/NIF in LI and HI cooked hams, respectively. The two ham types differed in lipid oxidation odourants: polyunsaturated fatty acid (PUFA) derivatives hexanal, 1-octen-3-one and (E,E)-2,4-decadienal were higher in LI ham; while monounsaturated fatty acid (MUFA) derivative decanal was higher in HI. HI samples resulted in higher values for odour-active aroma compounds from Maillard reaction, which are related to roast flavour and a higher overall flavour liking. In summary, our results suggest that Maillard derived odour-active aroma compounds were partially inhibited in LI samples (high in PUFA), resulting in lower positive sensory ratings.

  8. Flows and chemical reactions in homogeneous mixtures

    CERN Document Server

    Prud'homme, Roger

    2013-01-01

    Flows with chemical reactions can occur in various fields such as combustion, process engineering, aeronautics, the atmospheric environment and aquatics. The examples of application chosen in this book mainly concern homogeneous reactive mixtures that can occur in propellers within the fields of process engineering and combustion: - propagation of sound and monodimensional flows in nozzles, which may include disequilibria of the internal modes of the energy of molecules; - ideal chemical reactors, stabilization of their steady operation points in the homogeneous case of a perfect mixture and c

  9. 美拉德反应对苜蓿青贮品质的影响%Effect of Maillard Reaction on the Quality of Alfalfa Silage

    Institute of Scientific and Technical Information of China (English)

    李改英; 傅彤; 孙宇; 廉红霞; 高腾云

    2012-01-01

    This research was conducted to study the effect of maillard reaction on the quality of alfalfa silage by adding 5% molasses.The results showed that maillard reaction destroyed the nutrition value of alfalfa silage and the difference was notable for the content of crude protein,crude fat and soluble sugar compared with the silage material and the good alfalfa silagc(P0.05) , but with the silage time prolonging and the occurance of maillard reaction, Cys was ascending and there was no difference(P> 0.05) ,and then the conent of Val and lie of alfalfa silage was more than the content of silage material, while the content of maillard reaction alfalfa silage was less than the content of silage material and alfalfa silage, and the difference was distinct(p<0.05) , for the other 14 kinds of amino acid and total amino acid, the content presented a reducing trend, and the dropping extent of Lys was the most.%试验研究了美拉德反应对添加5%糖蜜的苜蓿青贮品质的影响.结果表明:美拉德反应严重破坏了苜蓿青贮饲料的营养价值,粗蛋白质、粗脂肪和可溶性糖分含量均与青贮原料和正常的青贮料差异显著(P<0.05),且随着青贮时间的延长,正常青贮料的粗蛋白质和粗脂肪也随之发生显著性下降(P<0.05).苜蓿青贮后酸性洗涤纤维(ADF)变化不显著,中性洗涤纤维(NDF)为下降趋势,发生美拉德反应后ADF和NDF均为升高的趋势(P<0.05).17种氨基酸的含量在青贮前期变化不显著(P>0.05),随着青贮时间的延长和美拉德反应的发生,半胱氨酸有升高的趋势,但差异不显著(P>0.05),缬氨酸和异亮氨酸含量青贮料高于青贮原料(P>0.05),发生美拉得反应的苜蓿其含量低于青贮原料和青贮料,且差异显著(P<0.05),其它14种氨基酸和总氨基酸含量均为降低趋势,其中以赖氨酸降幅最大(77%).

  10. Investigations on the effect of antioxidant type and concentration and model system matrix on acrylamide formation in model Maillard reaction systems.

    Science.gov (United States)

    Constantinou, Costas; Koutsidis, Georgios

    2016-04-15

    The formation of acrylamide in model Maillard reaction systems containing phenolic compounds was examined, with regards to phenolic type, concentration, and model system matrix. In dry glyoxal/asparagine waxy maize starch (WMS) systems, 9 out of 10 examined phenolics demonstrated an inhibiting effect, with the most significant reductions (55-60%) observed for caffeoylquinic acids. In WMS glucose/asparagine systems, examination of three different concentrations (0.1, 0.5 and 1 μmol/g WMS) suggested a 'minimum effective concentration' for epicatechin and caffeic acid, whilst addition of caffeoylquinic acids resulted in dose-dependent acrylamide reduction (25-75%). The discordant results of further studies utilising different matrices (dry and wet-to-dry) indicated that, apart from the nature and chemical reactivity, the matrix and the physical state of the reactants might be important for acrylamide formation.

  11. 正交设计法优化培养基中美拉德反应条件以提高猪苓菌核产量的研究%Study on Optimization of Maillard Reaction Conditions in Culture Medium to Enhance Yield of Polyporus umbellatus Sclerotium by Orthogonal Design

    Institute of Scientific and Technical Information of China (English)

    尹婉嫱; 郭顺星

    2011-01-01

    目的 用正交设计法优化培养基中美拉德反应的条件,以提高猪苓菌核产量.方法 以果糖和精氨酸作为美拉德反应的原料,经过调节pH后在一定温度下独立灭菌一定时间,之后与含蛋白胨和无机盐的培养基混合均匀并用于诱导猪苓菌核.以菌核干重为指标,对灭菌前pH值,果糖与精氨酸浓度比,灭菌时间(min),灭菌温度(℃)4个因素进行了k(34)正交实验.结果 极差分析结合方差分析表明,灭菌前pH值对菌核产量具有显著影响.优化后反应条件为:灭菌前pH为10;浓度比为200:1;灭菌时间为80 min;灭菌温度为121℃.菌核产率提高了75%,菌核干重提高到每皿(0.225±0.16)g.结论 相比优化前菌核产率为30% ~50%,菌核干重为每皿0.1~0.15 g,新的反应条件显著提高了菌核产量.%OBJECTIVE To optimize Maillard reaction conditions in culture medium by orthogonal design so as to enhance yield of Polyporus umbellatus sclerotium. METHODS According to our previous study, it was found that Maillard reaction products in fructose medium might play a role in sclerotial induction in P. Umbellatus. Maillard reaction products, as indicated in the references, varied with reaction time, carbon-nitrogen ratio in reactants, as well as pH value and temperature in reaction system. In this study, Fructose and arginine of different concentration ratios were mixed and used as reactants for Maillard reaction after pH value adjustment, which were sterilized for some time under a specific temperature. The mixture was subsequently mixed with medium containing peptone and mineral salts. The ultimate medium was used for inducing sclerotium of P. Umbellatus. Maillard reaction conditions were optimized by a L9(34)orthogonal design, in which, pH value before sterilization( A), concentration ratio( B) , sterilization time(C)and sterilization temperature (D) were the four factors to modulate. Each factor had three levels. Sclerotium dryweight was

  12. Behaviour and hormonal status in healthy rats on a diet rich in Maillard reaction products with or without solvent extractable aroma compounds.

    Science.gov (United States)

    Sebeková, Katarína; Klenovics, Kristína Simon; Boor, Peter; Celec, Peter; Behuliak, Michal; Schieberle, Peter; Heidland, August; Palkovits, Miklós; Somoza, Veronika

    2012-02-01

    Maillard reaction products (MRPs) are generated upon thermal processing of foods, modifying their colour and flavour. We asked whether aroma compounds generated via Maillard-type reactions modulate the in vivo effects of MRP-rich diets (MRPD). Male Wistar rats were fed for 3weeks either with a standard rat chow, an aroma compounds containing MRPD comprising 25% bread crust, or an aroma-extracted MRPD. In contrast to standard rat chow, consumption of MRPDs affected glucose control, induced hyper-leptinemia and hyper-adiponectinemia. Plasma adipokines were significantly higher in rats on aroma containing MRPD in comparison with those consuming aroma-extracted MRPD. Consumption of both MRPDs significantly increased the expression of the insulin receptor in the olfactory bulb, and mildly in the hypothalamus. Administration of the aroma containing MRPD significantly increased the leptin receptor expression in the olfactory bulb, and in the hypothalamus. Under both MRPDs, strong expression of c-fos indicated an increased neuronal activity in the olfactory bulb. Neuronal activity in brain areas involved in the central regulation of food intake and energy homeostasis was more pronounced in rats fed by the aroma containing MRPD. In conclusion, short-term consumption of a MRPD fortified with bread crust, particularly if containing solvent extractable volatile aroma compounds, affected the leptin-induced central signalling of anorexigenic/orexigenic hormones, and the neuronal activity in the central nervous system. Behavioural changes and altered glucose control were more evident in rats on the aroma containing MRPD. Our data suggest that volatile aroma compounds in foods might affect endocrine signalling and neuronal regulation of metabolism.

  13. 烟末酶解物美拉德反应配料的优化%The Ingredient Optimization of Maillard Reaction of Tobacco Enzymatic Hydrolysate

    Institute of Scientific and Technical Information of China (English)

    文冬梅; 伍锦鸣; 赵谋明; 卓浩廉; 赵强忠; 郭文

    2013-01-01

    以烟末酶解物为基液,通过添加不同的氨基酸与糖类,进行美拉德反应,选择出合适的氨基酸与糖,同时通过GC-MS检测了氨基酸与部分糖类发生的美拉德反应.结果表明:从评吸得分和褐变程度来看,甘氨酸和木糖是比较合适的氨基酸和糖类,且糖氨比为2∶1时,具有良好的风味;GC-MS结果表明:随着糖类的加入,产生了以吡嗪类、呋喃类、吡咯类及醛类为代表的25种风味物质.三种糖都产生了大量的糠醇,且木糖产生了其它两种糖所没有的6种呋喃类物质,同时风味得到了很好的改善.%In order to choose appropriate amino acid and saccharide to conduct Maillard reaction of tobacco enzymatic hydrolysate, different kinds of amino acids and saccharides were experimented and the volatile flavor compounds from Maillard reaction of amino acid and several saccharides were detected by GC-MS. The results demonstrated that xylose and glycine were the better choices from the perspective of the evaluation score and browning degree and good flavor was obtained by reaction of xylose with glycine at the ratio of 2:1. The GC-MS results showed that 25 kinds of flavor compounds generated and represented by pyrazdnes, furans, pyrroles and aldehydes after adding saccharides. Plenty of furfuralcohol was generated in three kinds of saccharides. Six kinds of Furans were generated in xylose. Furthermore, the flavor of product got well improved.

  14. DJ-1 family Maillard deglycases prevent acrylamide formation.

    Science.gov (United States)

    Richarme, Gilbert; Marguet, Evelyne; Forterre, Patrick; Ishino, Sonoko; Ishino, Yoshizumi

    2016-09-23

    The presence of acrylamide in food is a worldwide concern because it is carcinogenic, reprotoxic and neurotoxic. Acrylamide is generated in the Maillard reaction via condensation of reducing sugars and glyoxals arising from their decomposition, with asparagine, the amino acid forming the backbone of the acrylamide molecule. We reported recently the discovery of the Maillard deglycases (DJ-1/Park7 and its prokaryotic homologs) which degrade Maillard adducts formed between glyoxals and lysine or arginine amino groups, and prevent glycation damage in proteins. Here, we show that these deglycases prevent acrylamide formation, likely by degrading asparagine/glyoxal Maillard adducts. We also report the discovery of a deglycase from the hyperthermophilic archaea Pyrococcus furiosus, which prevents acrylamide formation at 100 °C. Thus, Maillard deglycases constitute a unique enzymatic method to prevent acrylamide formation in food without depleting the components (asparagine and sugars) responsible for its formation. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Implications of Partial Conjugation of Whey Protein Isolate to Durian Seed Gum through Maillard Reactions: Foaming Properties, Water Holding Capacity and Interfacial Activity

    Directory of Open Access Journals (Sweden)

    Bahareh Tabatabaee Amid

    2013-12-01

    Full Text Available This paper deals with the conjugation of durian seed gum (DSG with whey protein isolate (WPI through Maillard reactions. Subsequently, the functional properties of durian seed gum in the non-conjugated (control sample and conjugated forms were compared with several commercial gums (i.e., Arabic gum, sodium alginate, kappa carrageenan, guar gum, and pectin. The current study revealed that the conjugation of durian seed gum with whey protein isolate significantly (p < 0.05 improved its foaming properties. In this study, the conjugated durian seed gum produced the most stable foam among all samples. On the other hand, the emulsion stabilized with the conjugated durian seed gum also showed more uniform particles with a larger specific surface area than the emulsion containing the non-conjugated durian seed gum. The conjugated durian seed gum showed significant different foaming properties, specific surface area, particle uniformity and water holding capacity (WHC as compared to the target polysaccharide gums. The conjugated durian seed gum showed more similar functional properties to Arabic gum rather than other studied gums.

  16. Volatile fingerprints of seeds of four species indicate the involvement of alcoholic fermentation, lipid peroxidation, and Maillard reactions in seed deterioration during ageing and desiccation stress.

    Science.gov (United States)

    Colville, Louise; Bradley, Emma L; Lloyd, Antony S; Pritchard, Hugh W; Castle, Laurence; Kranner, Ilse

    2012-11-01

    The volatile compounds released by orthodox (desiccation-tolerant) seeds during ageing can be analysed using gas chromatography-mass spectrometry (GC-MS). Comparison of three legume species (Pisum sativum, Lathyrus pratensis, and Cytisus scoparius) during artificial ageing at 60% relative humidity and 50 °C revealed variation in the seed volatile fingerprint between species, although in all species the overall volatile concentration increased with storage period, and changes could be detected prior to the onset of viability loss. The volatile compounds are proposed to derive from three main sources: alcoholic fermentation, lipid peroxidation, and Maillard reactions. Lipid peroxidation was confirmed in P. sativum seeds through analysis of malondialdehyde and 4-hydroxynonenal. Volatile production by ageing orthodox seeds was compared with that of recalcitrant (desiccation-sensitive) seeds of Quercus robur during desiccation. Many of the volatiles were common to both ageing orthodox seeds and desiccating recalcitrant seeds, with alcoholic fermentation forming the major source of volatiles. Finally, comparison was made between two methods of analysis; the first used a Tenax adsorbent to trap volatiles, whilst the second used solid phase microextraction to extract volatiles from the headspace of vials containing powdered seeds. Solid phase microextraction was found to be more sensitive, detecting a far greater number of compounds. Seed volatile analysis provides a non-invasive means of characterizing the processes involved in seed deterioration, and potentially identifying volatile marker compounds for the diagnosis of seed viability loss.

  17. Effect of chitosan molecular weight on the functional properties of chitosan-maltose Maillard reaction products and their application to fresh-cut Typha latifolia L.

    Science.gov (United States)

    Li, Song-Lin; Lin, Jing; Chen, Xiao-Ming

    2014-02-15

    The objective was to evaluate antimicrobial, antioxidant and copper-chelating activities of Maillard reaction products (MRP) prepared from maltose and different molecular weight chitosan, and their effects on preservation of fresh-cut Typha latifolia L. (TLL). LMRP (maltose and low molecular weight chitosan MRP) showed the highest browning and UV absorbance as well as fluorescence intensity. The DPPH radical scavenging activity, reducing power and copper-chelating activity of chitosan-maltose MRP varied depending on the chitosan molecular weight. HMRP (maltose-high molecular weight chitosan MRP) exhibited better effects on inhibiting PPO activity and discoloration, alleviating declines of total soluble solids and ascorbic acid content of fresh-cut TLL. LMRP and MMRP (maltose-medium molecular weight chitosan MRP) effectively decreased weight loss and maintained firmness of TLL, respectively. These results indicated that molecular weight of chitosan had a great impact on the functional properties of chitosan-maltose MRP and their application to be used as a preservative. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. The effect of Maillard reaction products and yeast strain on the synthesis of key higher alcohols and esters in beer fermentations.

    Science.gov (United States)

    Dack, Rachael E; Black, Gary W; Koutsidis, Georgios; Usher, St John

    2017-10-01

    The effect of Maillard reaction products (MRPs), formed during the production of dark malts, on the synthesis of higher alcohols and esters in beer fermentations was investigated by headspace solid-phase microextraction GC-MS. Higher alcohol levels were significantly (p<0.05) higher in dark malt fermentations, while the synthesis of esters was inhibited, due to possible suppression of enzyme activity and/or gene expression linked to ester synthesis. Yeast strain also affected flavour synthesis with Saccharomyces cerevisiae strain A01 producing considerably lower levels of higher alcohols and esters than S288c and L04. S288c produced approximately double the higher alcohol levels and around twenty times more esters compared to L04. Further investigations into malt type-yeast strain interactions in relation to flavour development are required to gain better understanding of flavour synthesis that could assist in the development of new products and reduce R&D costs for the industry. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Odor-Active (E -4-Methyl-3-hexenoic Acid in Roasted Coffee Generated in the Maillard Reactions of L-Isoleucine with Sugars

    Directory of Open Access Journals (Sweden)

    Hironari Miyazato

    2013-10-01

    Full Text Available This study describes a novel odor-active unsaturated aliphatic acid in roasted Brazilian Arabica coffee. (E-4-Methyl-3-hexenoic acid -4M3H, which is responsible for a sweaty odor, was identified for the first time using Gas Chromatography-Mass Spectrometry/Olfactometry (GC-MS/O, Aroma Extract Dilution Analysis (AEDA and Multidimensional Gas Chromatography-Mass Spectrometry (MDGC-MS; its (Z -isomer was also determined. Additionally, we conducted a model formation experiment to detect the presence of 4M3H in coffee and found that it may be produced nonstereoselectively in the Maillard reactions of L-isoleucine with sugars (xylose, fructose, glucose, rhamnose and sucrose. We also found that 2-methylbutanal derived from L-isoleucine and sugar degradation compounds such as α-dicarbonyl compounds (glyoxal, 2-oxopropanal, 2, 3-butanedione and 2, 3-pentanedione and α-hydroxy ketones (1-hydroxy-2-propanone and 3-hydroxy-2-butanone are key factors in the formation of 4M3H. Based on these results, we propose a series of potential nonstereoselective formation pathways for 4M3H.

  20. Implications of partial conjugation of whey protein isolate to durian seed gum through Maillard reactions: foaming properties, water holding capacity and interfacial activity.

    Science.gov (United States)

    Amid, Bahareh Tabatabaee; Mirhosseini, Hamed; Poorazarang, Hashem; Mortazavi, Seyed Ali

    2013-12-06

    This paper deals with the conjugation of durian seed gum (DSG) with whey protein isolate (WPI) through Maillard reactions. Subsequently, the functional properties of durian seed gum in the non-conjugated (control sample) and conjugated forms were compared with several commercial gums (i.e., Arabic gum, sodium alginate, kappa carrageenan, guar gum, and pectin). The current study revealed that the conjugation of durian seed gum with whey protein isolate significantly (p < 0.05) improved its foaming properties. In this study, the conjugated durian seed gum produced the most stable foam among all samples. On the other hand, the emulsion stabilized with the conjugated durian seed gum also showed more uniform particles with a larger specific surface area than the emulsion containing the non-conjugated durian seed gum. The conjugated durian seed gum showed significant different foaming properties, specific surface area, particle uniformity and water holding capacity (WHC) as compared to the target polysaccharide gums. The conjugated durian seed gum showed more similar functional properties to Arabic gum rather than other studied gums.

  1. An unusual decarboxylative Maillard reaction between L-DOPA and D-glucose under biomimetic conditions: factors governing competition with Pictet-Spengler condensation.

    Science.gov (United States)

    Manini, P; d'Ischia, M; Prota, G

    2001-07-27

    In 0.1 M phosphate buffer at pH 7.4 and 37 degrees C, the tyrosine metabolite L-3,4-dihydroxyphenylalanine (L-DOPA) reacts smoothly with D-glucose to afford, besides diastereoisomeric tetrahydroisoquinolines 1 and 2 by Pictet-Spengler condensation, a main product shown to be the unexpected decarboxylated Amadori compound N-(1-deoxy-D-fructos-1-yl)-dopamine (3). Under similar conditions, dopamine gave only tetrahydroisoquinoline products 4 and 5, whereas L-tyrosine gave exclusively the typical Amadori compound 6. Fe(3+) and Cu(2+) ions, which accumulate in relatively high levels in parkinsonian substantia nigra, both inhibited the formation of 3. Cu(2+) ions also inhibited the formation of 1 and 2 to a similar degree, whereas Fe(3+) ions increased the yields of 1 and 2. Apparently, the formation of 3 would not be compatible with a simple decarboxylation of the initial Schiff base adduct, but would rather involve the decarboxylative decomposition of a putative oxazolidine-5-one intermediate assisted by the catechol ring. These results report the first decarboxylative Maillard reaction between an amino acid and a carbohydrate under biomimetic conditions and highlight the critical role of transition metal ions in the competition with Pictet-Spengler condensation.

  2. Antioxidant activity of the melanoidin fractions formed from D-Glucose and D-Fructose with L-Asparagine in the Maillard reaction

    Directory of Open Access Journals (Sweden)

    A.P Echavarría

    2013-01-01

    Full Text Available Melanoidins formed at the last stage of the Maillard reaction have been shown to possess certain functional properties, such as antioxidant activity. In order to gain more insight into these functional properties, soluble model systems melanoidins from L - Asparagine with D - glucose or D - fructose fractionating by ultrafiltration were analyzed. The fractionating/concentration sequence of the melanoidin fraction (1 - 300 kDa enabled five fractions to be produced. Additionally, the absorption of melanoidins was measured at different wavelengths (280, 325, 405 and browning at 420 nm. The fractionati on effect of melanoidin systems on the color intensity, UV - absorbance scan wavelengths (nm, CIE, L*, a*, b* parameters and antioxidant activity were measured. For this purpose, antioxidant activity was evaluated through the free radical scavenging activit y, including 1,1 - diphenyl - 2 - picryl - hydrazil (DPPH and 2,20 - azinobis (3 - ethylbenothiazoline - 6 - sulfonic acid, diammonium salt (ABTS. The results showed that the absorption of the melanoidins formed from Glucose/L - Asn was higher than for those derived from Fructose/L - Asn. On the other hand, their antioxidant power was lower than that for melanoidins formed from Fructose/L - Asn systems.

  3. Antioxidant activity of the melanoidin fractions formed from DGlucose and D-Fructose with L-Asparagine in the Maillard reaction

    Directory of Open Access Journals (Sweden)

    A.P Echavarría

    2013-03-01

    Full Text Available Melanoidins formed at the last stage of the Maillard reaction have been shown to possess certain functional properties, such as antioxidant activity. In order to gain more insight into these functional properties, soluble model systems melanoidins from L‑Asparagine with D‑glucose or D‑fructose fractionating by ultrafiltration were analyzed. The fractionating/concentration sequence of the melanoidin fraction (1-300 kDa enabled five fractions to be produced.Additionally, the absorption of melanoidins was measured at different wavelengths (280, 325, 405 and browning at 420 nm. The fractionation effect of melanoidin systems on the color intensity, UV-absorbance scan wavelengths (nm, CIE, L*, a*, b* parameters and antioxidant activity were measured. For this purpose, antioxidant activity was evaluated through the free radical scavenging activity, including 1,1-diphenyl-2-picryl-hydrazil (DPPH and 2,20-azinobis (3-ethylbenothiazoline-6-sulfonic acid, diammonium salt (ABTS. The results showed that the absorption of the melanoidins formed from Glucose/L-Asn was higher than for those derived from Fructose/L-Asn. On the other hand, their antioxidant power was lower than that for melanoidins formed from Fructose/L-Asn systems.

  4. Microwaves in chemistry: Another way of heating reaction mixtures

    Science.gov (United States)

    Berlan, J.

    1995-04-01

    The question of a possible "microwave activation" of chemical reaction is discussed. In fact two cases should be distinguished: homogeneous or heterogeneous reaction mixtures. In homogeneous mixtures there are no (or very low) rate enhancements compared to a conventional heating, but some influence on chemioselectivity has been observed. These effects derive from fast and mass heating of microwaves, and probably, especially under reflux, from different boiling rates and/or overheating. With heterogeneous mixtures non conventional effects probably derive from mass heating and selective overheating. This is illustrated with several reactions: Diels-Alder, naphthalene sulphonation, preparation of cyanuric acid, hydrolysis of nitriles, transposition reaction on solid support.

  5. In situ formation of the amino sugars 1-amino-1-deoxy-fructose and 2-amino-2-deoxy-glucose under Maillard reaction conditions in the absence of ammonia.

    Science.gov (United States)

    Nashalian, Ossanna; Yaylayan, Varoujan A

    2016-04-15

    Replacing amino acids with their binary metal complexes during the Maillard reaction can initiate various processes, including the oxidative degradation of their glucose conjugates, generating 1-amino-1-deoxy-fructose and its derivatives. These reactive amino sugars are not easily accessible under Maillard reaction conditions and are only formed in the presence of ammonia. To explore the generality of this observation and to study in particular the ability of fructose to generate glucosamine, the amino acid-metal complexes were heated in aqueous solutions with three aldohexoses and two ketohexoses at 110°C for 2 h and the dry residues were analysed by ESI/qTOF/MS/MS. All the sugars generated relatively intense ions at [M+H](+) 180 (C6H14NO5); those ions originating from ketohexoses exhibited MS/MS fragmentations identical to glucosamine and those originating form aldohexoses showed ions identical to fructosamine. Furthermore, the amino sugars were found to form fructosazine, react with other sugars and undergo dehydration reactions.

  6. Maillard reaction and enzymatic browning affect the allergenicity of Pru av 1, the major allergen from cherry (Prunus avium).

    Science.gov (United States)

    Gruber, Patrick; Vieths, Stefan; Wangorsch, Andrea; Nerkamp, Jörg; Hofmann, Thomas

    2004-06-16

    The influence of thermal processing and nonenymatic as well as polyphenoloxidase-catalyzed browning reaction on the allergenicity of the major cherry allergen Pru av 1 was investigated. After thermal treatment of the recombinant protein rPru av 1 in the absence or presence of carbohydrates, SDS-PAGE, enzyme allergosorbent tests, and inhibition assays revealed that thermal treatment of rPru av 1 alone did not show any influence on the IgE-binding activity of the protein at least for 30 min, thus correlating well with the refolding of the allergen in buffer solution as demonstrated by CD spectroscopic experiments. Incubation of the protein with starch and maltose also showed no effect on IgE-binding activity, whereas reaction with glucose and ribose and, even more pronounced, with the carbohydrate breakdown products glyceraldehyde and glyoxal induced a strong decrease of the IgE-binding capacity of rPru av 1. In the second part of the study, the effect of polyphenoloxidase-catalyzed oxidation of polyphenols on food allergen activity was investigated. Incubation of rPru av 1 with epicatechin in the presence of tyrosinase led to a drastic decrease in IgE-binding activity of the protein. Variations of the phenolic compound revealed caffeic acid and epicatechin as the most active inhibitors of the IgE-binding activity of rPru av 1, followed by catechin and gallic acid, and, finally, by quercetin and rutin, showing significantly lower activity. On the basis of these data, reactive intermediates formed during thermal carbohydrate degradation as well as during enzymatic polyphenol oxidation are suggested as the active chemical species responsible for modifying nucleophilic amino acid side chains of proteins, thus inducing an irreversible change in the tertiary structure of the protein and resulting in a loss of conformational epitopes of the allergen.

  7. Coffee and Maillard products activate NF-kappaB in macrophages via H2O2 production.

    Science.gov (United States)

    Muscat, Sonja; Pelka, Joana; Hegele, Jörg; Weigle, Bernd; Münch, Gerald; Pischetsrieder, Monika

    2007-05-01

    In this study, we investigated the immunomodulatory activity of coffee and Maillard reaction products on macrophages in vitro. Stimulation of macrophages with coffee, but not with raw coffee extract in PBS, led to a 13-fold increased nuclear NF-kappaB translocation. A Maillard reaction mixture (25 mM D-ribose/L-lysine, 30 min at 120 degrees C) increased NF-kappaB translocation 18-fold (in PBS) or six-fold (in medium). MRPs also induced a two-fold increased NF-kappaB translocation in untransfected human embryonic kidney (HEK) cells as well as in HEK cells stably transfected with the receptor for advanced glycation endproducts (RAGE), indicating that the effect was not RAGE mediated. On the other hand, catalase totally abolished coffee- and MRP-induced NF-kappaB translocation. Consequently, up to 366 microM hydrogen peroxide was measured in the coffee preparation and Maillard mixtures used for cell stimulation. Stimulation of macrophages with MRPs did not lead to significantly increased IL-6 or NO release. Thus, it can be concluded that coffee and MRPs induce NF-kappaB translocation in macrophages via the generation of hydrogen peroxide.

  8. Automatic NMR-based identification of chemical reaction types in mixtures of co-occurring reactions.

    Science.gov (United States)

    Latino, Diogo A R S; Aires-de-Sousa, João

    2014-01-01

    The combination of chemoinformatics approaches with NMR techniques and the increasing availability of data allow the resolution of problems far beyond the original application of NMR in structure elucidation/verification. The diversity of applications can range from process monitoring, metabolic profiling, authentication of products, to quality control. An application related to the automatic analysis of complex mixtures concerns mixtures of chemical reactions. We encoded mixtures of chemical reactions with the difference between the (1)H NMR spectra of the products and the reactants. All the signals arising from all the reactants of the co-occurring reactions were taken together (a simulated spectrum of the mixture of reactants) and the same was done for products. The difference spectrum is taken as the representation of the mixture of chemical reactions. A data set of 181 chemical reactions was used, each reaction manually assigned to one of 6 types. From this dataset, we simulated mixtures where two reactions of different types would occur simultaneously. Automatic learning methods were trained to classify the reactions occurring in a mixture from the (1)H NMR-based descriptor of the mixture. Unsupervised learning methods (self-organizing maps) produced a reasonable clustering of the mixtures by reaction type, and allowed the correct classification of 80% and 63% of the mixtures in two independent test sets of different similarity to the training set. With random forests (RF), the percentage of correct classifications was increased to 99% and 80% for the same test sets. The RF probability associated to the predictions yielded a robust indication of their reliability. This study demonstrates the possibility of applying machine learning methods to automatically identify types of co-occurring chemical reactions from NMR data. Using no explicit structural information about the reactions participants, reaction elucidation is performed without structure elucidation of

  9. Study on the process of Maillard reaction in producing beef extract%美拉德反应制备牛肉提取物的工艺研究

    Institute of Scientific and Technical Information of China (English)

    徐耀文; 刘微

    2013-01-01

    Process for producing beef extract by Maillard reaction were studied.Beef extract was made from fresh beef as raw material through biological enzyme solution or boiling extraction,concentration of raw materials and add other seasoning.It was rich in amino acids,peptides,polysaccharides and other nutrients.In this study,beef extract and Maillard reaction were combined,and beef extract was prepared by Maillard reaction flavor principle.According to the orthogonal experiment method and sensory evaluation,the optimum conditions of Maillard reaction in producing beef extract were determined:vitamin B10.4%,L-cysteinel.2%,beef tallow 5%,glucose 4%,reaction temperature 115℃,reaction time 60minutes.According to the best Maillard reaction conditions produced beef extract.The product was full-bodied,natural.And it had the following characteristics:1.mellow flavor of meat,2.the after taste and delicious,3.aromatizing effect,4.highlight the flavor characteristics of food.It can be widely used in meat products,instant noodles,condiments,frozen food,leisure food and other fields,which can provide reference for the research and development of such products.%对利用美拉德反应制备牛肉提取物的工艺进行了研究.牛肉提取物是以新鲜牛肉为原料通过生物酶解或熬煮提取,浓缩后加入其他调味原料精制而成.富含氨基酸、肽类、多糖等营养成分.本研究将牛肉提取物和美拉德反应相结合,利用美拉德反应生香原理制备了牛肉提取物.根据正交试验和感官评定方法确定了牛肉提取物美拉德反应的最佳条件为:维生素B10.4%,L-半胱氨酸1.2%,牛脂5%,葡萄糖4%,反应温度115℃,反应时间60分钟.根据最佳美拉德反应条件制作了牛肉提取物产品.该产品香气口感浓郁,真实自然,具有以下特点:1、肉味醇厚,肉香浓郁;2、产生后味和厚味;3、赋香效果;4、便于突出食品的风味特性.可广泛应用于肉制品、

  10. Effects of Vitamin C on the Simple Model Maillard Reaction System%Vc对简单模拟美拉德反应体系的影响

    Institute of Scientific and Technical Information of China (English)

    曾茂茂; 李伶俐; 何志勇; 秦昉; 陈洁

    2012-01-01

    In order to simulate real food system more closely, and to investigate the effects of reducing sugar ana- logue on simple simulation system, we tested the effects of vitamin C addition on the concentrations of residual glu- cose, cysteine, glycine and vitamin C, as well as melanoidin, pH value and sensory evaluation. The results have demonstrated that with the increasing concentration of vitamin C, the residual glucose increased gradually, the residu- al cysteine increased first and then decreased, the residual glycine decreased first and then became stable, vitamine C residual increased gradually. The absorbance at 420 nm (melanoidin) increased first and then decreased, pH value decreased gradually, the pungent smell of sulfur increased first and then became stable; the meat flavor decreased gradually, but the toast flavor was almost the same. Moreover, the sensory evaluation scores were the highest when the addition concentration of vitamin C was 0.05mol/L. These results have provided certain basis for research of rea! maillard reaction system, especially the interaction of the components in the system.%为了更加接近实际食品体系,研究还原糖相似物对简单美拉德反应体系的影响,文中以葡萄糖/半胱氨酸为模拟体系,考察了在甘氨酸存在情况下,Vc对该体系残余葡萄糖、半胱氨酸、甘氨酸和Vc的浓度,体系褐色物质和pH值,以及感官质量评定结果的影响。结果表明:随着添加Vc含量的增加,葡萄糖残余含量逐渐增大,半胱氨酸残余含量先增大后减小,甘氨酸残余含量先减小后趋于平衡,残余Vc的含量逐渐增大,体系420nm吸光值先(褐色物质)增大后减小,pH值逐渐减小,体系硫的刺激性气味先上升后稳定,肉味逐渐下降,而烘烤味则变化不大,并且在Vc添加含量为0.05mol/L时体系的感官评定分数最高。

  11. Oxidation state of BZ reaction mixtures.

    Science.gov (United States)

    Sobel, Sabrina G; Hastings, Harold M; Field, Richard J

    2006-01-12

    The unstirred, ferroin (Fe(phen)(3)2+)-catalyzed Belousov-Zhabotinsky (BZ) reaction1-4 is the prototype oscillatory chemical system. After an induction period of several minutes, one sees "spontaneous" formation of "pacemaker" sites, which oscillate between a blue, oxidized state (high [Fe(phen)3(3+)]) and a red, reduced state (low [Fe(phen)(3)3+]). The reaction medium appears red (reduced) during the induction phase, and the pacemaker sites generate target patterns of concentric, outwardly moving waves of oxidation (blue). Auto-oscillatory behavior is also seen in the Oregonator model of Field, Korös, and Noyes (FKN), a robust, reduced model which captures qualitative BZ kinetics in the auto-oscillatory regime. However, the Oregonator model predicts a blue (oxidized) induction phase. Here, we show that including reaction R8 of the FKN mechanism, not incorporated in the original Oregonator, accounts for bromide release during the induction phase, thus producing the observed red oxidation state.

  12. Characteristic fluorescence of bovine serum albumin and different sugar Maillard reaction systems%牛血清白蛋白与不同糖美拉德反应体系的荧光光谱学研究

    Institute of Scientific and Technical Information of China (English)

    刘建垒; 黎庆; 邢效娟; 景浩

    2015-01-01

    目的:本文研究了牛血清白蛋白(bovine serum albumin, BSA)与不同单糖(木糖、葡萄糖、半乳糖)和双糖(乳糖、麦芽糖)美拉德反应体系的荧光特性。方法首先将BSA与不同糖按摩尔浓度比1:667混合于磷酸盐缓冲溶液(pH 7.4)中,在50℃加热7 d后得到BSA与不同糖的美拉德反应体系;进一步用三维荧光光谱及同步荧光光谱研究了BSA与不同糖美拉德反应体系的荧光变化。结果 BSA与不同糖美拉德反应体系在三维荧光光谱中产生了一个新的特征荧光峰(λex 330~340 nm,λem 400~425 nm),其荧光强度随反应时间的延长逐渐增大。同步荧光光谱(Δλ=15 nm和Δλ=60 nm)的最大发射波长均发生了不同程度的蓝移。三维荧光光谱及同步荧光光谱的变化幅度均与体系美拉德反应进程一致,即美拉德反应程度由高到低依次为: BSA-Xyl>BSA-Gal>BSA-Glu, BSA-Mal, BSA-Lac。结论 BSA与不同糖美拉德反应体系中出现特征性新的荧光峰及蓝移,可作为监测美拉德反应进程及BSA构象改变的指标。%Objective The characteristic fluorescence of Maillard reaction systems (MRS) of bovine serum albumin (BSA) and different monosaccharides (xylose, glucose, and galactose) and disaccharides (lactose and maltose) were investigated. Methods BSA and different sugar Maillard reaction systems were prepared in phosphate buffer saline (pH 7.4) with a molar ratio of 1:667, and heated at 50 ℃ for 7 days. The fluorescence development of the BSA and sugar MRS were assessed by 3-dimensional fluorescence and synchronous fluorescence. Results The BSA and sugar MRS exhibited the characteristic new fluorescence peaks (λex 330~340 nm, λem 400~425 nm) on 3-dimensional fluorescence spectra, and their fluorescence intensity increased with heating time. The blue shifts of the maximum emission wave lengths occurred on synchronous fluorescences (Δλ=15 nm and Δλ=60 nm). The degree of fluorescence change of

  13. 葡萄糖浆颜色发黄与美拉德反应%The glucose syrup produce browning color via the Maillard reaction

    Institute of Scientific and Technical Information of China (English)

    张志华; 刘书盈

    2005-01-01

    在淀粉糖工业生产过程中,葡萄糖浆颜色时而会发黄,追究其原因有两种:一种是生产过程中葡萄糖浆的温度局部偏高,糖浆被烤糊而呈黄色;另一种则是由于葡萄糖浆本身质量所影响。下面我们介绍一下与淀粉糖生产有关的美拉德反应(Maillard)。

  14. 罗非鱼鱼排蛋白酶解液美拉德反应生香工艺优化研究%Optimization of Maillard Reaction Aroma Process of the Hydrolysate of Tilapia (Oreochromis niloticus) Frames Protein

    Institute of Scientific and Technical Information of China (English)

    熊何健; 操龙飞; 鄢庆枇; 马英

    2013-01-01

    In order to study the Maillard reaction aroma process of the hydrolysate of tilapia, the effects of four factors, reaction temperature, heating time, pH value and amount of reducing sugar, on Maillard reaction products (MRPS) were evaluated using sensory analysis method, and the Response Surface Methodology (RSM) was applied to optimize the process. The optimum conditions for Maillard reaction were 57 min reaction time, 111℃ reaction temperature, pH 6.0 and reducing sugar of 2.0% (the ratio of glucose and xylose was 2:1). The HPLC analysis showed that the content of organic acid in the MRPS was higher than before, and the flavour guanosine monophosphate (GMP) was detected in the MRPS, while it was not detected in enzymatic hydrolysate. The GC-MS analysis results showed that the volatile ingredients in the MPRS included 68 kinds of flavor compounds, they were 6 kinds of alcohols, 7 of aldehydes, 5 of ketones, 7 of aromatic compounds, 11 of esters, 8 of furan, 9 of pyrazine, 1 of pyrrole, 7 of hydrocarbons, 5 of acids and 2 of sulfur compounds, respectively. Under the optimized conditions, the Maillard reaction products (MRPS) were transparent, red-brown with a unique flavor of the fish. The flavor was rich and had a lasting fragrance.%为了对罗非鱼鱼排蛋白酶解液美拉德反应生香工艺进行研究,以风味总体接受性为指标,对反应温度、时间、pH值、还原糖添加量4个因素采用响应面法进行多元回归拟合,优化美拉德反应条件,并用HPLC、GC-MS对反应产物进行分析.结果表明:美拉德反应最佳工艺条件为反应时间57 min,反应温度111℃,pH 6.0,还原糖(葡萄糖∶木糖=2∶1)添加量2.0%;反应产物中有机酸含量较反应前酶解液中有机酸含量丰富,核酸关联物较反应前多了呈味的鸟苷酸;反应产物中挥发性成分包括68种风味化合物,分别是醇类6种、醛类7种、酮类5种、芳香族7种、酯类11种、呋喃8种、吡嗪9种、吡咯1

  15. Effect of Maillard reaction on lipid oxidation in the energy bar during the storage%能量棒贮藏过程中美拉德反应对油脂氧化的影响

    Institute of Scientific and Technical Information of China (English)

    马月; 董新娜; 李博

    2015-01-01

    能量棒富含蛋白质、糖和油脂.为探究能量棒中美拉德反应和油脂氧化之间的相互作用,检测了常温(25℃)贮藏过程中产品色差及过氧化值的变化,在此基础上选取45、65℃2个温度进行加速试验,测定了加速贮藏过程中产品色差、还原糖含量的变化,同时检测能量棒和其提取油脂在相同加速条件下的过氧化值,并对能量棒与对照油脂相比过氧化值的降低量和能量棒还原糖的减少量进行相关性分析.结果表明:能量棒贮藏过程中会发生显著的褐变反应以及一定的油脂氧化.45和65℃2个加速温度一定时间内,过氧化值的降低量与还原糖减少量均呈正相关,相关系数R2分别为0.973和0.967,说明在此条件下,能量棒中美拉德反应对能量棒油脂氧化有显著的抑制作用.而65℃条件下贮存15 d后,油脂过氧化物的积累表现出加速美拉德反应的作用.因此,油脂的氧化和美拉德反应之间的影响是相互制约的.%Energy bar is rich in protein,carbohydrate and lipid.In order to study the interaction of the Maillard reaction and lipid oxidation,the variation of chromatics and peroxide value in the room temperature (25 ℃) were measured.The accelerated experiments were carried out under 45 and 65 ℃.The variation of chromatics and reducing sugar content were measured.Peroxide value of energy bar and pure oil was compared during the accelerated experiments.The amount of peroxide value and reducing sugar content were compared for correlation analysis.The results showed that significant browning and slight lipid oxidation were occurred in the energy bar during the storage.The reduced amount of peroxide value and reducing sugar were positive correlated during the accelerated experiments of 45 ℃ and 65 ℃.Pearson Correlation Coefficient R2 was 0.973 and 0.967 respectively.The results provided that the products of Maillard reaction can significantly inhibit the lipid oxidation in

  16. Study on preparation of beef-like flavor by Maillard reaction of pollock steak hydrolysate%狭鳕鱼排酶解物美拉德反应制备牛肉香型风味物

    Institute of Scientific and Technical Information of China (English)

    许瑞红; 闫虹; 杨立; 范选娇; 林琳; 姜绍通; 陆剑锋

    2015-01-01

    以狭鳕鱼排酶解液为原料,研究美拉德反应制备牛肉香型风味物的工艺,在单因素的基础上通过正交试验优化,得到工艺参数为:葡萄糖3.0g/100 mL,木糖1.0g/100 mL,VB11.25g/100 mL,L-半胱氨酸盐酸盐1�5g/100 mL,牛肉酶解液30mL/100 mL,pH值5.0,温度120℃,时间120min,在此条件下风味物具有纯正、浓郁的牛肉香气。美拉德反应后,游离氨基酸中损失率最大的为苏氨酸(高达63.02%),表明此氨基酸是参与美拉德反应的主要氨基酸。此外,从美拉德反应产物中共检测到76种挥发性化合物,包括含硫类3种、醛类22种、酮类7种、酯类4种、醚类1种、烷烃类24种、羧酸类3种,其中甲硫醇、2-甲基-3-呋喃硫醇、3-甲硫基丙醛、正己醛、辛醛、苯乙醛、(E,E)-2,4-壬二烯醛和反式-2,4-癸二烯醛等被鉴定为重要的具有牛肉特征风味物质。%Pollock steak hydrolysate was taken as material to study preparation of beef-like flavor by Maillard reaction. Based on single factor experiments, through the orthogonal experiment the optimal technology parameters were obtained. The results showed that beef-like flavor with pure and strong beef fragrance was obtained under the conditions of 3. 0 g/100 mL glucose, 1. 0 g/100 mL xylose, 1. 25 g/100 mL thiamine, 1. 5 g/100 mL L-cysteine hydrochloride, 30 mL/100 mL beef hydrolysate, pH 5. 0, temperature 120 ℃ and reacting time 120 min. After Maillard reaction the loss ratio of threonine was biggest (up to 63. 02%) among free amino acid. It indicated that threonine was the key amino acid in⁃volved in the Maillard reaction. Furthermore, totally 76 kinds of volatile compounds were identified from the Maillard reaction products, including 3 kinds of sulphur compounds, 22 kinds of aldehydes, 7 kinds of ketones, 4 kinds of esters , 1 kind of ethers, 24 kinds of hydrocarbons and 3 kinds of

  17. N(ε)-Carboxymethyllysine (CML), a Maillard reaction product, stimulates serotonin release and activates the receptor for advanced glycation end products (RAGE) in SH-SY5Y cells.

    Science.gov (United States)

    Holik, Ann-Katrin; Rohm, Barbara; Somoza, Mark M; Somoza, Veronika

    2013-07-01

    Maillard reaction products, which are formed in highly thermally treated foods, are commonly consumed in a Western diet. In this study, we investigated the impact of N(ε)-carboxymethyllysine (CML), a well-characterized product of the Maillard reaction, on the gene regulation of the human neuroblastoma cell line SH-SY5Y. Pathway analysis of data generated from customized DNA microarrays revealed 3 h incubation with 50 μM and 500 μM CML to affect serotonin receptor expression. Further experiments employing qRT-PCR showed an up-regulation of serotonin receptors 2A, 1A and 1B after 0.25 h and 3 h. In addition, 500 μM CML increased serotonin release, thus showing effects of CML not only at a genetic, but also at a functional level. Intracellular calcium mobilization, which mediates serotonin release, was increased by CML at concentrations of 0.05-500 μM. Since calcium mobilization has been linked to the activation of the receptor for advanced glycation end products (RAGE), we further investigated the effects of CML on RAGE expression. RAGE was found to be up-regulated after incubation with 500 μM CML for 0.25 h. Co-incubation with the calcium blocker neomycin for 0.25 h blocked the up-regulation of RAGE and the serotonin receptors 2A, 1A and 1B. These results indicate a possible link between a CML-induced calcium-mediated serotonin release and RAGE.

  18. Pervaporation applied for dewatering of reaction mixture during esterification

    Directory of Open Access Journals (Sweden)

    Krasiński Andrzej

    2016-03-01

    Full Text Available In this work the esterification of diethyl tartrate was studied. The research was focused on the enhancement of reversible reaction yield, which is accomplished by dewatering of the reaction mixture. The removal of water shifts the equilibrium towards the main product. Pervaporation was applied for this purpose, and results were compared to distillation. The advantages and limitations of both processes are discussed. The experimental part consists of dewatering of mixture after the reaction had reached the equilibrium, and was subsequently fed to the test rig equipped with a single zeolite membrane purchased from Pervatech B.V. Results show a significant conversion increase as a result of water removal by pervaporation. Compared to distillation no addition of organics is necessary to efficiently remove water above the azeotrope. Nevertheless, some limitations and issues which call for optimisation are pointed out. A simple numerical model is proposed to support design and sizing of the pervaporation system. Various modes of integrated system operation are also briefly discussed.

  19. Role of phosphate and carboxylate ions in maillard browning.

    Science.gov (United States)

    Rizzi, George P

    2004-02-25

    The Maillard reaction of carbohydrates and amino acids is the underlying chemical basis for flavor and color formation in many processed foods. Phosphate and other polyatomic anions will accelerate the rate of Maillard browning, and this effect has been explained by invoking enhanced proton abstraction from intermediate Amadori compounds. In this work, the effect of phosphate and carboxylate ions on browning was measured for a series of reducing sugars with and without the presence of beta-alanine. Significant browning was observed for sugars alone suggesting that polyatomic anions contribute to Maillard browning by providing reactive intermediates directly from sugars. A mechanism is proposed for decomposition of sugars by polyatomic anions and efforts to trap reactive species using o-phenylenediamine (OPD) are described. The results of this study suggest how complications may arise from the popular usage of phosphate buffers in the study of Maillard reaction kinetics. In addition, the results imply how phosphates may be useful for enhancing browning during food processing.

  20. Effect of pulsed electric field treatment on Maillard reaction of reducing sugars with glutamic acid-Na%脉冲电场对还原糖-谷氨酸钠体系美拉德反应的影响

    Institute of Scientific and Technical Information of China (English)

    陈刚; 于淑娟

    2011-01-01

    主要研究了脉冲电场对于不同还原糖-谷氨酸钠溶液的pH、中间产物、褐变、还原糖含量以及抗氧化活性的影响.结果显示:脉冲电场处理条件为场强4kV/cm,时间1.88ms,得到果糖-甘氨酸钠体系在294nm和420nm的吸光值从0分别增加到1.71和0.07,同时,抗氧化活性增加10.96%,果糖含量减少55%.气质分析表明,经脉冲电场处理可以引发葡萄糖、蔗糖、麦芽糖和乳糖分别与谷氨酸钠体系的美拉德反应,产物包括苯的衍生物、酰胺及醛,但是在果糖-谷氨酸钠反应液中发现了丙烷、醋酸和丁内酯.研究证明,脉冲电场是一种提高还原糖-谷氨酸钠体系美拉德反应的有效方法.%Effects of pulsed electric field on pH, intermediate products, browning, reducing sugar content, and antioxidant activity of different reducing sugar-glutamic acid-Na solutions were examined.Results showed that the pulsed electric field treatment at the intensity of 4kV/cm for 1.88ms resulted in the pronounced increases of the fructose- glutamic acid - Na solution' s absorbance at 294nm and 420nm and the antioxidant activity from approximately 0 to 1.71,0.07 and 10.96%,respectively.At the same time,55% reduction in fructose was observed. Gas Chromatography/Mass Spectrum analysis showed that the pulsed electric field treatment induced a Maillard reaction in the glucose-,sucrose-,maltose-and lactose-glutamic acid-Na model systems producing substances including benzene derivatives, acylamide or aldehydes, while, propane, acetic acid, butyrolactone were found in fructose-glutamic acid-Na reacted solution.This study indicated that pulsed electric field could potentially be employed as a means to promote the Maillard reaction in the reducing sugars-glutamic acid-Na solutions.

  1. 木糖-草鱼肽美拉德反应产物的抗氧化性%Antioxidant activity of Maillard reaction products derived from xylose and ctenopharyngodon idellus peptide

    Institute of Scientific and Technical Information of China (English)

    赵谋明; 刘洋; 张佳男; 吴长平; 苏国万

    2014-01-01

    Oxidative deterioration of oil and protein is a common problem in the food industry, which led to trending studies of safe antioxidants with strong antioxidant activity. Ctenopharyngodon Idellus is a commercial fish, which is rich in proteins and polyunsaturated fatty acids, and is widely distributed in fresh-water throughout China,. In recent years, the Ctenopharyngodon Idellus was prepared as condiment or nourishment, however, further studies are limited. In this study, Ctenopharyngodon Idellus was hydrolyzed by three proteases (papain, PTN6.0, and Alcalase2.4 L), and the hydrolysate was isolated at two fractions of molecular weight above and below 5 kD by ultrafiltration. The fraction below 5 kD (Ctenopharyngodon Idellus peptide) was heated with or without xylose at 100℃for different times (30 min to 240 min). Oxygen radical absorbance capacity (ORAC), reducing power, UV absorption, and volatile components of Maillard reaction products (MRPs) and thermal degradation products (TDPs) with different reaction times were evaluated, respectively. This study focuses on the effects of Maillard reaction on the antioxidant activity and the volatile components from Ctenopharyngodon Idellus peptide and its derivatives. The correlation between reaction products, volatile components, and their antioxidant activity were also analyzed. Results revealed that the browning intensity and UV absorption of the intermediate products of MRPs were much higher than those of TDPs. Antioxidant activity of MRPs increased with increasing heat time, while TDPs had no obvious change. In addition, MRPs showed better antioxidant activity. Reducing power and oxygen radical absorbance capacity of MRPs for 240 min was 17.77 and 3.32 times than those untreated. 51 kinds of volatile compounds were separated and identified from MRPs; among them, pyrazines, furans, pyrroles, aldehydes, ketones, and alcohols had relatively high concentration. Whereas, aldehydes were the largest content of volatile

  2. 大豆蛋白美拉德反应产物在肉糜保鲜中的应用%Application of Soybean Protein Maillard Reaction Products in Minced Meat Storage

    Institute of Scientific and Technical Information of China (English)

    李芳菲; 郑环宇; 孔保华; 夏秀芳

    2016-01-01

    The influence of Maillard reaction products(MRPs) prepared with isolated soybean protein(SPI) on physicochemical properties in ripe minced meat was investigated by measuring thiobarbituric acid reactive sub-stanc (TBARS), a*-value, pH and sensory evaluation. Results showed that MRPs exhibited antioxidant effect in the cooked meat batter, which could inhibit the lipid oxidation, keep batter colour and a good overall ac-ceptability. Moreover, the antioxidant effect was better with more MRPs addition. In terms of colour and antioxi-dant effect, there was no significant difference between the batter with 2.0%MRPs and with 0.02%butyl hy-droxy anisole (P>0.05), however, there was a significant difference between the batter with 2.0%MRPs and the control (P0.05),与其他处理组和对照组存在显著性差异(P<0.05)。因此,大豆分离蛋白美拉德反应产物能够作为一种安全的抗氧化剂添加到熟肉糜中,提高抗氧化能力,保持感官特性,延长货架期。

  3. The Maillard hypothesis on aging: time to focus on DNA.

    Science.gov (United States)

    Baynes, John W

    2002-04-01

    Aging is the outcome of the contest between chemistry and biology in living systems. Chronic, cumulative chemical modifications compromise the structure and function of biomolecules throughout the body. Proteins with long life spans serve as cumulators of exposure to chemical damage, which is detectable in the form of advanced glycation and lipoxidation end products (AGEs, ALEs); amino acids modified by reactive oxygen, chlorine, and nitrogen species; and deamidated and racemized amino acids. Not all of these modifications are oxidative in nature, although oxidative reactions are an important source of age-related damage. Measurements of AGEs and ALEs in proteins are useful for assessing the rate and extent of Maillard reaction damage, but it is the damage to the genome that undoubtedly has the greatest effect on the viability of the organism. The extent of genomic damage represents a balance between the rate of modification and the rate and fidelity of repair. Damage to DNA accumulates not in the form of modified nucleic acids, but as chemically "silent" errors in repair-insertions, deletions, substitutions, transpositions, and inversions in DNA sequences-that affect the expression and structure of proteins. These mutations are random, vary from cell to cell, and are passed forward from one cell generation to another. Although they are not detectable in DNA by conventional analytical techniques, purines and pyrimidines modified by Maillard reaction intermediates may be detectable in urine, and studies on these compounds should provide insight into the role of Maillard reactions of DNA in aging and disease.

  4. Maillard-reactie door model beheersbaar

    NARCIS (Netherlands)

    Roost, van M.

    2006-01-01

    Gewenste en ongewenste bruinkleuring van levensmiddelen door een Maillard-reactie is vaak lastig te beheersen. Wageningse onderzoekers ontwikkelden een simulatiemodel, waarmee producentenmeer inzicht krijgen in de Maillard-reactie, en zo ook de kleur van het eindproduct beter kunnen beheersen tijden

  5. Reaction Sintering of Mexican Dolomite – Zircon Mixtures

    Directory of Open Access Journals (Sweden)

    Rodríguez-Galicia, J. L.

    2005-08-01

    Full Text Available The present work has been conducted aiming to develop additional phase [Ca3SiO5, Ca2SiO4 and/or Ca3Mg(SiO42]-bonded magnesia refractory materials via reaction sintering of dolomite-zircon mixtures, employing a Mexican dolomite containing an excess of 3 wt% of CaCO3. The study was based on phase equilibrium data extracted from the quaternary system CaO – MgO – SiO2 – ZrO2, to put it more precisely, base on the projection from the MgO-apex of the liquidus surface of the primary crystallization volume of MgO onto the opposite face of the above mentioned quaternary system. The refractory materials designed within this system were obtained by attrition milling, followed by cold isostatic pressing and high temperature reaction sintering. All initial and produced materials were characterized by ICP-AES, XRF, XRD, SEM-EDX, DTA and TG analyses. The results obtained indicated that reaction sintering of dolomite-zircon mixtures is an interesting route to produce MgO-CaZrO3-additional phase refractory materials.

    El propósito de este trabajo ha sido obtener materiales refractarios de magnesia, aglomerados con una fase adicional [Ca3SiO5, Ca2SiO4 y/o Ca3Mg(SiO42], mediante la sinterización reactiva de mezclas de dolomita-circón, empleando para ello una dolomita mexicana que contiene un exceso de 3% en peso de CaCO3. El estudio se basa en la información relativa al equilibrio de fases del sistema CaO – MgO – SiO2 – ZrO2. En concreto se usa la proyección, desde el vértice del MgO, de la superficie de liquidus del volumen de cristalización primaria de este, hacia la cara opuesta de sistema cuaternario. Los materiales refractarios diseñados se han obtenido por molienda de atrición, seguida de un prensado isostático en frío y sinterización reactiva a alta temperatura. Todos los materiales, iniciales y finales, han sido caracterizados mediante ICPAES, FRX, DRX, MEB-EDX, ATD y TG. Los resultados obtenidos indican que la sinterizaci

  6. Analysis and Evaluation of Flavor Compounds in Maillard Reaction Products of Jellyfish Protein Peptic Hydrolysate%海蜇皮酶解液美拉德反应产物的风味鉴定与分析

    Institute of Scientific and Technical Information of China (English)

    张玲; 罗嘉滨; 海金萍; 张旭

    2012-01-01

    以海蜇皮酶解液和葡萄糖为主要底物进行美拉德反应,制得鱼味香料基液。感官评价知该香料基液咸度适口,鲜味明显,微甜,具有明显的鱼香味,香气协调。采用氨基酸自动分析仪测定了香料基液中游离氨基酸的种类和含量,采用GC-MS测定了香料基液醚溶物的挥发性风味成分及含量,以此对香料基液的风味进行了鉴定和分析。结果显示,香料基液中共检出17种游离氨基酸,总含量为2.7197g/dL,必需氨基酸(包括His和Arg)占游离氨基酸总量的48.86%,鲜味氨基酸(Asp和Glu)含量为17.76%,对滋味贡献较大的氨基酸是Glu、Lys、Gly、His和Arg;香料基液醚溶物中共分离鉴定出41香气成分,其中烃类8.71%,醇类58.35%,酯类13.65%,酸类17.86%,酮、醛类共0.42%,含氮含硫类共3.38%。对香气可能有重要贡献的化合物有丙二醇、乙酸乙酯、邻苯二甲酸二丁酯、4-甲基-5-噻唑乙醇、3,5-二叔丁基苯酚及少量的醛、酮类化合物。%Spice liquid was produced from jellyfish protein peptic hydrolysate and glucose through the Maillard reaction.The Maillard reaction products(MRPs) had an appropriate salinity,a distinct delicious taste,a slight sweetness and a harmonious fish-like aroma.To identify and analyze their flavor,the contents of amino acids in the MRPs were analyzed using an automated amino acid analyzer and the contents of volatile compounds in their ether-soluble fraction were determined by GC-MS.The results showed that 17 kinds of free amino acids with a total content of 2.7197 g/dL were detected.The total amount of the ten essential amino acids(including His and Arg) was 48.86% of total amino acids,and the content of tasty amino acids(Asp and Glu) was 17.76%.Glu,Lys,Gly,His and Arg had a significant contribution to the taste of the MRPs.Totally 41 kinds of aroma components were separated and identified,which were composed of 8.71% alkanes,58.35% alcohols,13.65% esters,17

  7. Study of emulsifying properties of Maillard reaction products of maltose-wheat gluten%麦芽糖-小麦面筋蛋白Maillard反应产物乳化性研究

    Institute of Scientific and Technical Information of China (English)

    王亚平; 刘进玺; 王金水

    2014-01-01

    The emulsifying properties of wheat gluten were studied after reacting with maltose(Maillard reaction). The results indicated that a remarkable improvement in emulsion activity index(EAI)of the gluten treated by maltose. The single factor and orthogonal tests of wheat gluten by maltose treatment were carried out. The optimum conditions were:pH 8,gluten/maltose ratio 3∶1,concentration of gluten 10%,reaction time 3 d,the EAI value of the obtained compound was 35.14 m2/g. The dispersing properties and thermostability of maltose-wheat gluten conjugates were raised greatly. The isoelectric points of conjugates was about pH 8.0 and the denature temperature was 98.1℃.%该文研究了小麦面筋蛋白与麦芽糖在控制条件下通过Maillard反应生成复合物的乳化性,并研究了复合物分散性的变化和热特性(DSC)的变化。结果表明:与麦芽糖发生Maillard反应明显改善了小麦面筋蛋白的乳化活性(Emulsion Activity Index,EAI),通过正交试验得到Maillard反应改善小麦面筋蛋白乳化性的最佳条件为:pH=8、小麦面筋蛋白/麦芽糖比为3∶1、小麦面筋蛋白浓度为10%、反应时间为3 d,Maillard反应产物的EAI值为35.14 m2/g。麦芽糖-小麦面筋蛋白复合物的分散性和热稳定性大大提高,复合物的等电点为pH 8.0左右,变性温度98.1℃。

  8. Optimization of thermal stability of barley protein-glucose maillard reaction by response surface methodology%响应面分析法在大麦蛋白-葡萄糖Maillard反应物热稳定性研究中的应用

    Institute of Scientific and Technical Information of China (English)

    董学艳; 刘继超; 王晓丹; 聂妤; 赵长新

    2011-01-01

    酿造大麦是啤酒生产过程中最重要的原料,大麦中的蛋白质对麦芽与啤酒的质量起着重要的作用,其中蛋白的热稳定性对啤酒泡沫的形成和稳定均具有重要的作用.国内外的研究表明,通过美拉德反应能够有效地改善蛋白质的功能特性.本论文主要研究美拉德反应对于大麦蛋白热稳定性的影响,通过二次回归通用旋转正交试验设计,应用响应面分析法对大麦蛋白-葡萄糖(Pr-G)Maillard反应过程中的各反应条件进行分析,建立数学模型,优化反应条件参数,以求得到热稳定性佳的Pr-G Maillard反应共聚物.结果表明:在90℃、pH9.08、反应时间为39.00min、大麦蛋白-葡萄糖的配比为1:1.04可以得到高热稳定性的反应共聚物.在此最佳反应条件下对反应共聚物的热稳定性进行了研究,证实了预测值和实测值是一致的.%Brewing barley is the most important raw material in beer production. The protein in the barley plays an important part in the quality of malt and beer, and the heat -stable protein plays important roles on formation and stability of the beer foam. It was reported that the functional properties of protein could be modified by Maillard reaction. The effect of the thermal stability of barley protein by Maillard reaction was studied. The factors such as pH, the ratio of reactants and reaction time affecting the Maillard reaction kinetics were discussed. Response surface methodology was used to optimize Maillard reaction factors in order to get Maillard reaction with the highest thermal stability property.The results indicated that reaction temperature 90 ℃, pH 9.08, reaction time 40 min and weight ratio of barley protein to glucose 1: 1.04 were the optimum reaction conditions. Under the above conditions, the thermal stability of conjugation was studied, and it was confirmed that the predicted and actual value of the thermal stability were identical.

  9. Structure-reactivity modeling using mixture-based representation of chemical reactions

    Science.gov (United States)

    Polishchuk, Pavel; Madzhidov, Timur; Gimadiev, Timur; Bodrov, Andrey; Nugmanov, Ramil; Varnek, Alexandre

    2017-07-01

    We describe a novel approach of reaction representation as a combination of two mixtures: a mixture of reactants and a mixture of products. In turn, each mixture can be encoded using an earlier reported approach involving simplex descriptors (SiRMS). The feature vector representing these two mixtures results from either concatenated product and reactant descriptors or the difference between descriptors of products and reactants. This reaction representation doesn't need an explicit labeling of a reaction center. The rigorous "product-out" cross-validation (CV) strategy has been suggested. Unlike the naïve "reaction-out" CV approach based on a random selection of items, the proposed one provides with more realistic estimation of prediction accuracy for reactions resulting in novel products. The new methodology has been applied to model rate constants of E2 reactions. It has been demonstrated that the use of the fragment control domain applicability approach significantly increases prediction accuracy of the models. The models obtained with new "mixture" approach performed better than those required either explicit (Condensed Graph of Reaction) or implicit (reaction fingerprints) reaction center labeling.

  10. Effect of theanine and polyphenols enriched fractions from decaffeinated tea dust on the formation of Maillard reaction products and sensory attributes of breads.

    Science.gov (United States)

    Culetu, Alina; Fernandez-Gomez, Beatriz; Ullate, Monica; del Castillo, Maria Dolores; Andlauer, Wilfried

    2016-04-15

    The antiglycoxidative properties of theanine (TEF) and polyphenols enriched fractions (PEF) prepared from tea dust were tested in a model system composed of bovine serum albumin (BSA) and methylglyoxal (MGO). PEF caused a decrease in available free amino groups of BSA in presence and absence of MGO, suggesting the simultaneous occurrence of glycoxidation reaction and phenols-protein interaction. The presence of PEF and TEF inhibited formation of fluorescent advanced glycation end-products (AGEs). Moreover, theanine (TB) and polyphenol-enriched bread (PB) were formulated. A significant increase in free amino groups was observed in TBs with a dose-response effect, while addition of PEF in bread produced a significant decrease (pfood ingredient allows obtaining a tasty food possessing health promoting properties and lower content of potential harmful compounds (AGEs).

  11. Effects of NMR transition point temperature on Maillard reaction rate in model food storage systems%NMR转折点温度对食品储存过程中Maillard反应速率影响

    Institute of Scientific and Technical Information of China (English)

    张锦胜; 林向阳; 阮榕生; Paul Chen

    2008-01-01

    Functional nuclear magnetic resonance (NMR) was used to study the effect of NMR state diagram and transition point temperature (Tp) on Maillard reaction rate in model food systems. All systems had the same concentration of reactants, lysine and glucose, but different moisture and inert components, trehalose and sucrose. Carr-Purcell-Meiboom-Gill(CPMG) sequence was used to acquire the sample's NMR relaxation data at different temperatures. High performance liquid chromatography (HPLC) was used to detect the consumption of reactants in the model food systems during stored in different temperatures. A trend of Tp temperatures change in the NMR state diagram was observed in the model matrixes with different moistures and sugar contents. A relative higher Tp temperature was observed in the low moisture sugar matrix and a relative slow reaction velocity in the identical matrix during storage at the same time. There were obvious reaction velocity differences on the temperatures above and below the Tp temperatures during storage at different temperatures. Different reaction velocities were observed in the samples having different sugar contents with same moisture during storage under an identical temperature. It was concluded that NMR state diagram and Tp temperature is available in accessing the better storage temperature, and an ingredient design would be helpful for the extension of shelf-life by decreasing the relative chemical reaction velocity during storage.%采用核磁共振(NMR)技术对以葡萄糖、海藻糖、蔗糖、赖氨酸构成的模型食品进行磁共振实验,绘制体系NMR状态图并计算转折点温度,同时在不同温度下进行储藏实验,考察体系中葡萄糖的变化,评估不同储藏温度下的Maillard反应速率.结果表明:模型食品体系含水量不同、非反应组分含量不同,其NMR转折点温度有所不同.低水分含量的体系具有相对高的NMR转折点温度.即使在相同的储藏温度下,含水量相

  12. 不同糖与乳清蛋白的美拉德反应对β-乳球蛋白致敏性的影响%Effect of Maillard Reaction between Whey Protein and Different Sugars on the Allergenicity of β-Lactoglobulin

    Institute of Scientific and Technical Information of China (English)

    曹寒馨; 汪何雅; 钱和

    2012-01-01

    In our current study, SDS-PAGE and indirect ELISA were both used to investigate the effect of Maillard reaction between whey protein and different sugars on the allergenicity of β-lactoglobulin. It was indicated that better results were achieved when pentose instead of hexose, a monosaccharide instead of a polysaccharide or a thermo-instable polysaccharide instead of a thermostable one was used to react with whey protein. Xyololigosaccharide had less effect on the flavor of Maillard reaction products, resulted in a lower browning rate, and was more effective in reducing the allergenicity of β -lactoglobulin.%通过十二烷基磺酸钠-聚丙烯酰胺凝胶电泳与间接竞争酶联免疫吸附法研究不同种类糖与乳清蛋白发生美拉德反应后对β-乳球蛋白致敏性的影响。结果显示:五碳糖效果好于六碳糖,单糖效果好于多糖,加热后热降解的多糖效果好于热稳定的多糖;综合褐变率与抑制率,低聚木糖对风味的影响较小,褐变率显示低聚木糖对感官影响较小,且降低致敏性效果较好。

  13. Reaction pathways in catechol/primary amine mixtures

    OpenAIRE

    Yang, Juan; Saggiomo, Vittorio; Velders, Aldrik H.; Cohen Stuart, Martien; Kamperman, Marleen

    2016-01-01

    Catechol chemistry is used as a crosslinking tool abundantly in both natural organisms (e.g. mussels, sandcastle worms) and synthetic systems to achieve the desired mechanical properties. Despite this abundance and success, the crosslinking chemistry is still poorly understood. In this study, to simplify the system, yet to capture the essential chemistry, model compounds 4-methyl catechol and propylamine are used. The reaction of 4-methyl catechol (2 mM) with propylamine (6 mM) is carried out...

  14. Decreasing Reducing Sugar Content in Reconstituted Tobacco by Maillard Reaction%利用美拉德反应降低再造烟叶中的还原糖

    Institute of Scientific and Technical Information of China (English)

    高徐梅; 李新生; 严新龙; 王军

    2014-01-01

    In order to decrease the content of reducing sugar in reconstituted tobacco (RT), Maillard reaction was brought about by adding amino acids in tobacco extract and FeCl3 as catalyst, going through extract concentration under reduced pressure, applying and drying steps analogous to real RT production. The content of reducing sugar was determined with HPLC, and the effects of different amino acids, addition rates of amino acids and catalyst, pH of extract, and conditions of extract concentrating, applying and drying on the reducing sugar content were investigated. The results showed that: 1) When reducing sugar/amino acid ratio in extract was 1∶0.5 (mole ratio), Fe3+ concentration 0.01 mmol/L, pH adjusted to about 6.2 by 2.5 mol/L K2CO3, the content of reducing sugar in RT could be decreased subject to simulated concentrating, applying and drying. Comparing with the control, the reducing sugar content in RT treated with lysine, glycine and proline decreased by 10.6%, 9.1% and 6.0%, respectively. 2) Comparing with the control, the irritancy of the RT treated with amino acids decreased to a certain extent, the aftertaste was improved; and the glycine-treated RT offered the best smoking quality.%为降低再造烟叶中还原糖含量,模拟生产中烟草萃取液减压浓缩、涂布烘烤等步骤,在萃取液中添加适量氨基酸,以氯化铁(FeCl3)为催化剂进行美拉德反应;采用高效液相色谱法测定还原糖含量变化,研究了不同种类氨基酸及其用量、催化剂用量、萃取液pH以及浓缩与涂布烘烤条件对降低还原糖含量的影响。结果表明:①当萃取液中还原糖∶氨基酸(摩尔比)=1∶0.5时,反应体系中Fe3+含量为0.01 mmol/L ,用2.5 mol/L K2CO3调节pH至6.2左右,模拟生产条件进行减压浓缩和涂布烘烤,可降低再造烟叶中还原糖含量。其中赖氨酸反应效果最好,相对于空白,再造烟叶中还原糖含量降低10.6%;甘

  15. Genotoxic Maillard byproducts in current phytopharmaceutical preparations of Echinodorus grandiflorus

    Directory of Open Access Journals (Sweden)

    ELISANGELA C. LIMA-DELLAMORA

    2014-09-01

    Full Text Available Extracts of Echinodorus grandiflorus obtained from dried leaves by three different techniques were evaluated by bacterial lysogenic induction assay (Inductest in relation to their genotoxic properties. Before being added to test cultures, extracts were sterilized either by steam sterilization or ultraviolet light. Only the extracts prepared by infusion and steam sterilized have shown genotoxic activity. The phytochemical analysis revealed the presence of the flavonoids isovitexin, isoorientin, swertisin and swertiajaponin, isolated from a genotoxic fraction. They were assayed separately and tested negative in the Inductest protocol. The development of browning color and sweet smell in extracts submitted to heat, prompted further chemical analysis in search for Maillard's reaction precursors. Several aminoacids and reducing sugars were cast in the extract. The presence of characteristic Maillard's melanoidins products was determined by spectrophotometry in the visible region and the inhibition of this reaction was observed when its characteristic inhibitor, sodium bisulfite, was added prior to heating. Remarkably, this is the first paper reporting on the appearance of such compounds in a phytomedicine preparation under a current phytopharmaceutical procedure. The genotoxic activity of such heat-prepared infusions imply in some risk of developing degenerative diseases for patients in long-term, uncontrolled use of such phytomedicines.

  16. 虾蟹壳提取物氨基葡萄糖美拉德反应及其产物的抗氧化性能研究%MAILLARD REACTION OF SHRIMP CRAB GLUCOSAMINE AND ANTIOXIDANT ACTIVITIES OF ITS MRPs (MAILLARD REACTION PRODUCTS)

    Institute of Scientific and Technical Information of China (English)

    唐杰; 刘必谦; 周湘池; 庄怡; 林晓彰

    2012-01-01

    首次使用虾蟹壳提取物氨基葡萄糖单一物质制备美拉德反应产物(MRPs)。结果表明,MRPs清除DPPH·能力随反应物浓度、温度和时间的增加而增强;还原能力、清除·OH能力随反应物浓度增加而增强,还原能力随温度、时间增加先增后降,清除·OH能力随温度升高先增后降,随反应时间下降。115℃、0.5mg/ml、90min条件下制备的MRPs清除DPPH·的能力最强为88.73%;65℃、0.6mg/ml、40min的MRPs还原能力最强为A700nm=1.684;65℃、0.6mg/ml、10min的MRPs清除·OH的能力最强为98.72%。MRPs具有很强的抗氧化活性,比Vc和TBHQ抗氧化效果更好,但其抗氧化能力并不完全依赖于产物的褐变程度。氨基葡萄糖MRPs是优良的新型保鲜剂材料。%For the first time preparation of the MRPs which is base on single material glucosamine originated from shrimp crab chitosan. The result suggested that MRPs' ability to scavenge the DPPH. free radicals increased as the reactant concentration, reaction temperature and reaction time did. Its reducing power and ability to scavenge the .OH free radicals as the reactant concentration increased. Meanwhile, the reducing power of MRPs first increased and then decreased as the increase of the reaction temperature and reaction time. Its ability of scavenging the .OH free radicals first increased then decreased with the increase of the reaction temperature and decreased with the increase of reaction time. The results of the orthogonal experiments indicated that the highest ability of MRPs, which was prepared with the concentration of 0.5mg/ml for 90rain at 115℃, scavenging DPPH- free radicals was 88.73%, its highest reducing power prepared with the concentra- tion of 0.6mg/ml for 40min at 65℃ was A700nm = 1.684, and its highest ability to scavenge -OH free radicals with the con- centration of 0.6mg/ml for 10min at 65℃ was 98.72%. These results presented that there

  17. Effect of flavonol on reduction of acrylamide in Maillard reaction and its correlation with antioxidant capacity%黄酮醇抑制丙烯酰胺在美拉德反应中的形成及与抗氧化间的相关性

    Institute of Scientific and Technical Information of China (English)

    程军; 任一平; 张英; 章宇

    2013-01-01

    genetic and reproductive toxicities as well as mutagenic and carcinogenic properties . Therefore , it is necessary to find effective additive agents to reduce the formation of acrylamide in Maillard reaction .We investigated the effects of flavonols on the reduction of acrylamide in an equimolar asparagine‐glucose Maillard reaction system using potato matrix and microwave heating . To investigate the dose‐response effect , six different levels of flavonols were added into the self‐prepared Maillard reaction system and different levels of acrylamide were generated and observed . Meanwhile , the correlation between the inhibitory rate of acrylamide affected by flavonols and the change of Trolox equivalent antioxidant capacity ( ΔTEAC ) in Maillard reaction products was also evaluated . Acrylamide levels in Maillard reaction products were determined by ultra‐high performance liquid chromatography coupled with tandem mass spectrometry ( U HPLC‐MS/MS ) and quantified with multiple reaction monitoring ( MRM ) mode after the pretreatment of final products . ΔTEAC values were simultaneously measured by three representative antioxidant evaluation methods , i .e . DPPH ( 1 ,1‐diphenyl‐2‐picrylhydrazyl) , ABTS ( 2 ,2‐azino‐bis‐3‐ethylbenzothiazoline‐6‐sulfonic acid) and FRAP ( ferric reducing ability of plasma) . The results indicated a non‐linear relationship between addition levels of flavonols and inhibitory rate of acrylamide . The optimal addition level of all six flavonols , i .e . kaempferol , kaempferol‐3‐o‐glucoside , quercetin , quercetin‐3‐o‐glucoside , myricetin and rutin was 1 × 10-9 mol/L , which exerted their maximal inhibitory effect against the generation of acrylamide . The inhibitory rate ranged from 48 .9% to 69 .3% when different types of flavonols were used at the optimal addition level . Taking ΔTEAC as the antioxidant measurement index , the correlation coefficients between ΔTEAC determined by three different

  18. Mixture

    Directory of Open Access Journals (Sweden)

    Silva-Aguilar Martín

    2011-01-01

    Full Text Available Metals are ubiquitous pollutants present as mixtures. In particular, mixture of arsenic-cadmium-lead is among the leading toxic agents detected in the environment. These metals have carcinogenic and cell-transforming potential. In this study, we used a two step cell transformation model, to determine the role of oxidative stress in transformation induced by a mixture of arsenic-cadmium-lead. Oxidative damage and antioxidant response were determined. Metal mixture treatment induces the increase of damage markers and the antioxidant response. Loss of cell viability and increased transforming potential were observed during the promotion phase. This finding correlated significantly with generation of reactive oxygen species. Cotreatment with N-acetyl-cysteine induces effect on the transforming capacity; while a diminution was found in initiation, in promotion phase a total block of the transforming capacity was observed. Our results suggest that oxidative stress generated by metal mixture plays an important role only in promotion phase promoting transforming capacity.

  19. 乳清蛋白-麦芽糖糊精的Maillard反应复合物制备β-胡萝卜素纳米乳液%Preparation of β-carotene nanoemulsions stablilized by Maillard Reaction Products of whey protein isolate and maltodextrin

    Institute of Scientific and Technical Information of China (English)

    李燕; 刘成梅; 刘伟; 钟俊桢

    2013-01-01

    系统考察乳液制备参数对乳液粒径分布及稳定性的影响,同时以干热法制备乳清分离蛋白(Whey Protein Isolate,WPI)-麦芽糖糊精(Maltodextrin,MD)的Maillard反应复合物(Maillard Reaction Products,MRPs).以此为基础,制备WPI-MD MRPs稳定的β-胡萝卜、素纳米乳液,并进一步考察乳液的物理稳定性及β-胡萝卜、素的化学稳定性.结果表明,WPI-MD的MRPs能够显著降低纳米乳液的粒径,并提高纳米乳液的物理稳定性.同时,WPI-MD的MRPs可加速油相中β-胡萝卜素的降解,其机理有待进一步研究.%Conditons for preparing nanoemulsions were investigated systematically. The Maillard Reaction Products(MRPs) were prepared by dry heating which were further used to prepare β-carotene nanoemulsions. The physical stability of the obtained nanoemulsions and the β-carotene degregation kinetics were simultaneously studied. The result showed that nanoemulsions stabilized by MRPs with smaller fat globe size were much physically stable compared with the nanoemulsions stablized by native WPI. However,the β-carotene in MRPs stablized nanoemulsions degradated more rapidly which mechanism should be futher studied in future.

  20. Miniature high-throughput chemosensing of yield, ee, and absolute configuration from crude reaction mixtures

    Science.gov (United States)

    Bentley, Keith W.; Zhang, Peng; Wolf, Christian

    2016-01-01

    High-throughput experimentation (HTE) has emerged as a widely used technology that accelerates discovery and optimization processes with parallel small-scale reaction setups. A high-throughput screening (HTS) method capable of comprehensive analysis of crude asymmetric reaction mixtures (eliminating product derivatization or isolation) would provide transformative impact by matching the pace of HTE. We report how spontaneous in situ construction of stereodynamic metal probes from readily available, inexpensive starting materials can be applied to chiroptical chemosensing of the total amount, enantiomeric excess (ee), and absolute configuration of a wide variety of amines, diamines, amino alcohols, amino acids, carboxylic acids, α-hydroxy acids, and diols. This advance and HTS potential are highlighted with the analysis of 1 mg of crude reaction mixtures of a catalytic asymmetric reaction. This operationally simple assay uses a robust mix-and-measure protocol, is amenable to microscale platforms and automation, and provides critical time efficiency and sustainability advantages over traditional serial methods. PMID:26933684

  1. Effect of Maillard induced glycation on protein hydrolysis by lysine/arginine and non-lysine/arginine specific proteases

    NARCIS (Netherlands)

    Deng, Y.; Wierenga, P.A.; Schols, H.A.; Sforza, S.; Gruppen, H.

    2017-01-01

    Enzymatic protein hydrolysis is sensitive to modifications of protein structure, e.g. Maillard reaction. In early stages of the reaction glycation takes place, modifying the protein primary structure. In later stages protein aggregation occurs. The specific effect of glycation on protein

  2. Secondary organic aerosol formation from ozone reactions with single terpenoids and terpenoid mixtures

    Science.gov (United States)

    Waring, Michael S.; Wells, J. Raymond; Siegel, Jeffrey A.

    2011-08-01

    Ozone reacts with indoor-emitted terpenoids to form secondary organic aerosol (SOA). Most SOA research has focused on ozone reactions with single terpenoids or with consumer products, and this paper reports the results from an investigation of SOA formation from ozone reactions with both single terpenoids and mixtures of D-limonene, α-pinene, and α-terpineol. Transient experiments were conducted at low (25 ppb) and high (100 ppb) initial concentrations of ozone. The three terpenoids were tested singly and in combinations in a manner that controlled for their different reaction rates with ozone. The SOA formation was assessed by examining the evolution in time of the resulting number size-distributions and estimates of the mass concentrations. The results suggest that at higher ozone and terpenoid concentrations, SOA number formation follows a linear trend as a function of the initial rate of reaction. This finding was valid for both single terpenoids and mixtures. Generally speaking, higher ozone and terpenoid concentrations also led to larger geometric mean diameters and smaller geometric standard deviations of fitted lognormal distributions of the formed SOA. By assuming a density, mass concentrations were also assessed and did not follow as consistent of a trend. At low ozone concentration conditions, reactions with only D-limonene yielded the largest number concentrations of any experiment, even more than experiments with mixtures containing D-limonene and much higher overall terpenoid concentrations. This finding was not seen for high ozone concentrations. These experiments demonstrate quantifiable trends for SOA forming reactions of ozone and mixtures, and this work provides a framework for expanding these results to more complex mixtures and consumer products.

  3. pH与反应温度对鸡骨素酶解液MRPs品质特性的影响%Characteristics of Maillard Reaction Products from Enzymatic Hydrolysate of Chicken Bone Extract as Influenced by pH and Temperature

    Institute of Scientific and Technical Information of China (English)

    胡礼; 王金枝; 张春晖; 唐春红; 杜桂红; 李侠; 李春红

    2015-01-01

    [目的]了解 pH 与反应温度对以鸡骨素酶解液为原料的 Maillard 反应的影响,分析美拉德反应产物(Maillard reaction products,MRPs)理化特性、感官品质及抗氧化性之间的关系,为高品质鸡骨素衍生化产品的开发提供工艺参考.[方法]在设定反应条件(pH 5.0、7.0、9.0;95℃、105℃、115℃)下,探讨反应条件对MRPs紫外吸收率、褐变程度、多肽分布、风味变化、感官品质及抗氧化性等指标的影响,分析各指标之间的相关性,并评价不同反应条件下各处理组MRPs的综合品质.[结果]通过比较各组合反应体系MRPs的吸光度,发现pH值增大能显著提高Maillard初级反应速率,温度升高导致MRPs褐变程度加剧.各体系分子量为1 000—200 Da的多肽含量均占MRPs多肽总量的50%以上,且与感官评分呈显著正相关(r=0.772,P<0.05).电子鼻(E-nose)与电子舌(E-tongue)风味特征主成分分析发现,各体系MRPs挥发性风味物质的生成易受温度影响,而滋味物质的生成易受pH影响.感官评价结果显示,随着pH增大,MRPs的感官评分减小,其中105℃、pH 5.0条件下制备的MRPs感官评分最高,比初始样品高57.32%.与pH 7.0、pH 9.0体系相比,pH 5.0条件下制备的MRPs还原力与ABTS+自由基清除能力均显著提高,而凝胶电泳结果显示MRPs对pBR322型超螺旋质粒DNA抗H2O2氧化损伤的保护能力与ABTS+清除能力呈显著正相关(r=0.689,P<0.05).结合层次分析确定指标权重与"合理-满意度"计算,得出pH 5.0、105℃处理组MRPs综合品质得分最高,为0.92.[结论]在鸡骨素酶解液Maillard反应体系中,pH及反应温度均显著影响MRPs品质特性.在本试验范围内,pH 5.0、105℃条件下更有利于制备高品质鸡骨素酶解液MRPs,在感官评价、色泽及抗氧化性等综合品质上优于其他各组.%[Objective]To obtain the desired flavor quality and antioxidant activity Maillard reaction products (MRPs) from enzymatic

  4. Pronase hydrolysis as a pretreatment for quantifying Maillard intermediates during toasting of cornflakes

    Directory of Open Access Journals (Sweden)

    Mario A. Cueto

    2016-04-01

    Full Text Available Some of the products generated by the Maillard reaction are desired and very important for defining consumer acceptance of breakfast cereals. However, in recent years there has been an increased concern about compounds that are potentially harmful such as furfurals. The aim of this work was to analyze the effectiveness of protein hydrolysis with pronase as a pretreament for the evaluation of furfurals generated by the Maillard reaction during toasting of cornflakes and the parallel development of brown and fluorescent compounds. Furfurals were more accurately quantified with the pronase hydrolysis pretreatment because the protein matrix binds furfurals and fluorescent compounds. For control of the early reaction steps in the toasting process, the most sensitive parameter was fluorescence.

  5. Controlled state-to-state atom-exchange reaction in an ultracold atom-dimer mixture

    CERN Document Server

    Rui, Jun; Liu, Lan; Zhang, De-Chao; Liu, Ya-Xiong; Nan, Jue; Zhao, Bo; Pan, Jian-Wei

    2016-01-01

    Ultracold molecules offer remarkable opportunities to study chemical reactions at nearly zero temperature. Although significant progresses have been achieved in exploring ultracold bimolecular reactions, the investigations are usually limited to measurements of the overall loss rates of the reactants. Detection of the reaction products will shed new light on understanding the reaction mechanism and provide a unique opportunity to study the state-to-state reaction dynamics. Here we report on the direct observation of an exoergic atom-exchange reaction in an ultracold atom-dimer mixture. Both the atom and molecule products are observed and the quantum states are characterized. By changing the magnetic field, the reaction can be switched on or off, and the reaction rate can be controlled. The reaction is efficient and we have measured a state-to-state reaction rate of up to $1.1(3)\\times10^{-9}$cm$^{3}/$s from the time evolution of the reactants and products. Our work represents the realization of a controlled q...

  6. Investigation of Glucose/Asparagine Model System Nonaqueous Phase Maillard Reaction by Thermogravimetry- Solid Phase Microextraction/Gas Chromatography - Mass Spectrometry%热重-固相微萃取/气相色谱-质谱联用研究葡萄糖/天冬酰胺模拟体系非水相Maillard反应

    Institute of Scientific and Technical Information of China (English)

    杨继; 杨柳; 卢岚; 吴亿勤; 曹秋娥

    2011-01-01

    利用热重-固相微萃取/气相色谱-质谱(TG-SPME/GC-Ms)联用对葡萄糖/天冬酰胺模拟体系非水相Maillard反应热学性质进行了研究,并分析了模拟体系46种热解逸出挥发性产物相对含量的动态变化情况.探讨了有效减少Maillard反应产物丙烯酰胺的方法.结果表明:葡萄糖/天冬酰胺模拟体系非水相Mail-lard反应热解过程经历4个强烈的热质量损失阶段,且每个质量损失段对应一个强烈的吸热峰,说明混合物反应需吸收热量,产生一系列的挥发性物质.葡萄糖/天冬酰胺混合物的降解活化能低于其各自降解的活化能.Maillard反应产物检出的色谱峰共有46个,其种类和含量随着温度的变化而变化,低温段生成物以长链烷烃、酮类、糠醛类为主;高温段产物主要为吡啶、吡咯、咪唑等含N杂环化合物.在该模拟体系中添加维生素C和阿魏酸是降低丙烯酰胺含量的有效途径,且添加维生素C对丙烯酰胺生成的抑制率大于阿魏酸.%A new combination system of thermogravimetry - sohd phase microextraction/gas chromatography- mass spectrometry( TG- SPME/GC- MS) was applied for analysis of the thermal properties of the glucose/asparagine model system nonaqueous phase Maillard reaction. 46 main pyrolysis evolved products were identified and the dynamic changes of relative content of these products were monitored. The heating rate and air flow was set at 10 ℃/min and 400 mL/min, respectively. The evolved components were extracted with solid phase microextraction in the temperature range of 50 400 ℃. A continuous sampling method was adopted at different temperature section according to the results of TG/DTA. There were 5 temperature zones in whole reaction process. Additionally, the extract was separated and analyzed by GC -MS. The results showed that the whole thermo decomposition procedure of glucose/asparagine could be divided into four stages. A lot of volatile flavor

  7. Reacting gas mixtures in the state-to-state approach: The chemical reaction rates

    Energy Technology Data Exchange (ETDEWEB)

    Kustova, Elena V. [Department of Mathematics and Mechanics, Saint Petersburg State University, 198504 Universitetskiy pr., 28, Saint Petersburg (Russian Federation); Kremer, Gilberto M. [Departamento de Física, Universidade Federal do Paraná, Caixa Postal 19044, 81531-980 Curitiba (Brazil)

    2014-12-09

    In this work chemically reacting mixtures of viscous flows are analyzed within the framework of Boltzmann equation. By applying a modified Chapman-Enskog method to the system of Boltzmann equations general expressions for the rates of chemical reactions and vibrational energy transitions are determined as functions of two thermodynamic forces: the velocity divergence and the affinity. As an application chemically reacting mixtures of N{sub 2} across a shock wave are studied, where the first lowest vibrational states are taken into account. Here we consider only the contributions from the first four single quantum vibrational-translational energy transitions. It is shown that the contribution to the chemical reaction rate related to the affinity is much larger than that of the velocity divergence.

  8. Reacting gas mixtures in the state-to-state approach: The chemical reaction rates

    Science.gov (United States)

    Kustova, Elena V.; Kremer, Gilberto M.

    2014-12-01

    In this work chemically reacting mixtures of viscous flows are analyzed within the framework of Boltzmann equation. By applying a modified Chapman-Enskog method to the system of Boltzmann equations general expressions for the rates of chemical reactions and vibrational energy transitions are determined as functions of two thermodynamic forces: the velocity divergence and the affinity. As an application chemically reacting mixtures of N2 across a shock wave are studied, where the first lowest vibrational states are taken into account. Here we consider only the contributions from the first four single quantum vibrational-translational energy transitions. It is shown that the contribution to the chemical reaction rate related to the affinity is much larger than that of the velocity divergence.

  9. Response Surface Optimization of Maillard Reaction Conditions and Analysis of Volatile Flavor Compounds of MRPs Derived from the Hydrolysate of Pneumatophorus Japonicns Heads%响应面优化鲐鱼头酶解液Maillard反应条件及其产物挥发性风味物质分析

    Institute of Scientific and Technical Information of China (English)

    徐大伦; 束玉珍; 杨文鸽; 楼乔明; 薛长湖

    2013-01-01

    Using the enzymolysis from pneumatophorus japonicns head as raw material,the effects of xylose additives,reaction time and temperature on the sensory evaluation of Maillard reaction products (MRPs) were determined by response surface method.Then the volatile flavor components of MRPs were isolated and identified by GC-MS.The results showed that the optimum conditions of Maillard reaction were as follows:xylose 2.5%,Gly 1.6%,ginger pop 10%,at 117 ℃ for 55 min.73 kinds of volatile flavor component were obtained,in which 2-ethyl furan,2-pentyl furan,ω-Heptaldehyde,(Z)-4-Heptenal,(E)-2-Octenal,(E,E)-2,4-Decadienal,4-Ethylbenzaldehyde,3-ethyl-Phenol,4-pentylphenol,Benzothiazole,4-Methylthiazole,Dimethyl trisulfide had an important contribution to the MRPs flavor.%以鲐鱼头酶解液为原料,通过响应面法研究木糖添加量、反应温度和时间对鲐鱼头酶解液美拉德反应产物(MRPs)感官的影响.用GC-MS分离鉴定MRPs中的挥发性风味物质,结果表明:鲐鱼头酶解液Maillard反应条件是:木糖、甘氨酸、姜汁添加量分别为2.5%、1.6%和10%,117℃反应55 min.经GC-MS分析鉴定,MRPs共含73种挥发性物质,其中2-乙基呋喃、2-戊基呋喃、ω-庚醛、(Z)4-庚烯醛、(E)-2-辛烯醛、(E,E)-2,4-癸二烯醛、4-乙基苯甲醛、3-乙基苯酚、4-戊基苯酚、苯并噻唑、4-甲基噻唑和二甲基三硫化物等化合物对MRPs的风味有重要贡献.

  10. Preparation of Non-meat Sources Meaty Flavor Essence from Yeast Extract by Maillard Reaction and Fuzzy Evaluation%啤酒酵母抽提物制备非肉源肉香型香精及模糊数学评价

    Institute of Scientific and Technical Information of China (English)

    卢茳虹; 崔春; 赵谋明

    2011-01-01

    以啤酒酵母抽提物为原科,不添加任何肉蛋白酶解液和油脂,采用测定美拉德反应产物的褐变程度、美拉德反应前后氨基酸态氮损失率以及评价美拉德反应产物的风味对美拉德反应参数进行优化,制备非内源肉香型香精,并采用模糊数学评价法进行评价.优化得到的反应条件为:复合还原糖(葡萄糖∶木糖=4∶1)添加2%(w/w按体系总量计),含硫化合物(半胱氨酸∶硫胺素=2∶1)添加1%(w/w,按体系总量计),在110℃下热反应60 min.模糊教学评价法评价在该工艺条件下制得的香精,内香逼真,风味浓郁纯正,评价等级为优.%This study tried to prepare non - meat sources meaty flavor essence by taking yeast extract as raw material without adding any meat protein hydrolyzates and fats. Based on the results of browning degree, the local flavor of the Maillard reaction products, as well as the comparison of the loss rate of amino acid nitrogen before and after the reaction, the Maillard reaction parameters were optimized. Meanwhile, the fuzzy mathematics was applied to the evaluation. The optimum conditions observed were as follows: compound sugar (glucose: xylose) 2% and suffur compounds( cysteine: VB1 ) 1% at 110℃ for 60min. The fuzzy evaluation was adopted to evaluate the organoleptic quality of essence at the optimum conditions which evaluation grade was excellent.

  11. Latent curing systems stabilized by reaction equilibrium in homogeneous mixtures of benzoxazine and amine

    Science.gov (United States)

    Wang, Jun; Xu, Ya Zhen; Fu, Ya Fei; Liu, Xiang Dong

    2016-12-01

    Latent curing systems are widely used in industrial thermosets in applications such as adhesion, coating, and composites. Despite many attempts to improve the practicality of this dormant reaction system, the majority of commercially available latent products still use particulate hardeners or liquid compounds with blocked active groups. These formulations generally lack fluidity or rapid reaction characteristics and thus are problematic in some industry applications. Here we describe a novel concept that stabilizes highly reactive benzoxazine/amine mixtures by reaction equilibrium. These new latent benzoxazine curing systems have a long storable lifetime but very short gel time at 150 °C. The reversible reaction between benzoxazine and amine is further demonstrated by FT-IR spectral measurements and rheological experiments, and it is shown that the overall characteristics of the latent system are promising for many industrial applications.

  12. Carboxymethylation of Cassava Starch in Different Solvents and Solvent-Water Mixtures: Optimization of Reaction Conditions

    Science.gov (United States)

    Nwokocha, Louis M.; Ogunmola, Gabiel B.

    The influence of reaction medium on carboxymethylation process was investigated by treating cassava starch with sodium monochloroacetate in different solvents and solvent-water mixtures under alkaline conditions. The amount of carboxyl groups introduced into the starch moiety was determined titrimetrically and used to calculate the Degree of Substitution (DS) and Reaction Efficiency (RE). The results showed that carboxymethylation is significantly affected by the nature of reaction medium at p<0.05. Carboxymethylation in different solvent-water mixtures showed that aqueous 80% n-propanol offered the best medium for carboxymethylation. Optimization of reaction conditions in aqueous 80% n-propanol showed that the best condition for carboxymethylation was at starch-liquor ratio of 1:3, NaOH/reagent molar ratio of 4.0 and reagent-starch molar ratio of 0.35. An increase in temperature was required to effect the reaction at shorter time. At 55°C the highest values of DS and RE achieved in 0.5 h would require three hours to achieve the same values of DS and RE at 45°C.

  13. Formation of Pyrazines and a Novel Pyrrole in Maillard Model Systems of 1,3-Dihydroxyacetone and 2-Oxopropanal

    NARCIS (Netherlands)

    Adams, A.; Polizzi, V.; Boekel, van T.; Kimpe, de N.

    2008-01-01

    Alkylpyrazines are a very important class of Maillard flavor compounds, but their mechanism of formation is complex and consists of different pathways. The model reaction of 20 different amino acids with 1,3-dihydroxyacetone, as a precursor of 2-oxopropanal, was studied by means of SPME-GC-MS to

  14. Reaction Mechanisms and HCCI Combustion Processes of Mixtures of n-Heptane and the Butanols

    Directory of Open Access Journals (Sweden)

    Hu eWang

    2015-03-01

    Full Text Available A reduced primary reference fuel (PRF-Alcohol-Di-tert-butyl Peroxide (DTBP mechanism with 108 species and 435 reactions, including sub-mechanisms of PRF, methanol, ethanol, DTBP and the four butanol isomers, is proposed for homogeneous charge compression ignition (HCCI engine combustion simulations of butanol isomers/n-heptane mixtures. HCCI experiments fuelled with butanol isomer/n-heptane mixtures on two different engines are conducted for the validation of proposed mechanism. The mechanism has been validated against shock tube ignition delays, laminar flame speeds, species profiles in premixed flames and engine HCCI combustion data, and good agreements with experimental results are demonstrated under various validation conditions. It is found that although the reactivity of neat tert-butanol is the lowest, mixtures of tert-butanol/n-heptane exhibit the highest reactivity among the butanol isomer/n-heptane mixtures if the n-heptane blending ratio exceeds 20% (mole. Kinetic analysis shows that the highest C-H bond energy in the tert-butanol molecule is partially responsible for this phenomenon. It is also found that the reaction tC4H9OH+CH3O2 =tC4H9O+CH3O2H plays important role and eventually produces the OH radical to promote the ignition and combustion. The proposed mechanism is able to capture HCCI combustion processes of the butanol/n-heptane mixtures under different operating conditions. In addition, the trend that tert-butanol /n-heptane has the highest reactivity is also captured in HCCI combustion simulations. The results indicate that the current mechanism can be used for HCCI engine predictions of PRF and alcohol fuels.

  15. Direct observations of reaction zone structure in shock-induced ignition of methane air mixture

    Institute of Scientific and Technical Information of China (English)

    WANG GaoFeng; MA ChengBiao; WANG BaoYuan; LIN QiZhao

    2009-01-01

    Ignition of methane/air mixture by the passage of a shock wave is an important issue for understanding more details of its gaseous detonation.The experiments of shock-induced ignition of stoichiometric methane/air mixture were conducted on a shock tube platform.The reaction zone structure in weak and strong ignition cases were investigated by digital chemiluminescence imaging and planar laser induced fluorescence (PLIF) techniques.Due to smaller gradients in induced time in weak ignition,which provided more time to nonlinear chemical reaction process,the results show that the reaction structures are highly nonuniform in those weak ignition cases,which become more regular while induced shock waves become stronger.In strong ignition case,it gives a typical detonation structure.The characteristics of reaction zone released by single-pulsed OH PLIF technique agreed well with other experimental measurements in this paper and were also in accord with the conclusions of previous researches.The successful implementation of the PLIF system has explored a new high temporally and spatially resolved method for the study of interaction between shock wave and gaseous matter in shock tube.

  16. Reaction of octenylsuccinic anhydride with a mixture of granular starch and soluble maltodextrin.

    Science.gov (United States)

    Bai, Yanjie; Shi, Yong-Cheng

    2013-11-06

    The reaction of octenylsuccinic anhydride (OSA) with a mixture of granular waxy maize starch and soluble maltodextrin was investigated. OSA was reacted with a 1:1 (w/w) mixture of the granular starch and maltodextrin at OSA levels of 1.5, 3, 9, and 15% (wt% based on starch weight). After the first 0.5h of the reaction, degree of substitution (DS) on maltodextrin reached 0.021, 0.030, 0.080, and 0.10 for 1.5, 3, 9, and 15% OSA, respectively, whereas DS for granular starch was only 0.0020, 0.0087, 0.014, and 0.016. At 2h of the reaction, the bound OS ratio of maltodextrin to granular starch was 10.8 when OSA concentration was 1.5% and the ratio decreased to ca. 5 at higher OSA concentrations. OSA preferred to react with maltodextrin than semi-crystalline granular starch when both existed in the system. OSA reacted with maltodextrin at a much faster rate and to a greater extent than with granular starch, but a significant amount of OSA reacted with granular starch at 3-15% OSA concentrations.

  17. Gas-Solid Reaction Route toward the Production of Intermetallics from Their Corresponding Oxide Mixtures

    Directory of Open Access Journals (Sweden)

    Hesham Ahmed

    2016-08-01

    Full Text Available Near-net shape forming of metallic components from metallic powders produced in situ from reduction of corresponding pure metal oxides has not been explored to a large extent. Such a process can be probably termed in short as the “Reduction-Sintering” process. This methodology can be especially effective in producing components containing refractory metals. Additionally, in situ production of metallic powder from complex oxides containing more than one metallic element may result in in situ alloying during reduction, possibly at lower temperatures. With this motivation, in situ reduction of complex oxides mixtures containing more than one metallic element has been investigated intensively over a period of years in the department of materials science, KTH, Sweden. This review highlights the most important features of that investigation. The investigation includes not only synthesis of intermetallics and refractory metals using the gas solid reaction route but also study the reaction kinetics and mechanism. Environmentally friendly gases like H2, CH4 and N2 were used for simultaneous reduction, carburization and nitridation, respectively. Different techniques have been utilized. A thermogravimetric analyzer was used to accurately control the process conditions and obtain reaction kinetics. The fluidized bed technique has been utilized to study the possibility of bulk production of intermetallics compared to milligrams in TGA. Carburization and nitridation of nascent formed intermetallics were successfully carried out. A novel method based on material thermal property was explored to track the reaction progress and estimate the reaction kinetics. This method implies the dynamic measure of thermal diffusivity using laser flash method. These efforts end up with a successful preparation of nanograined intermetallics like Fe-Mo and Ni-W. In addition, it ends up with simultaneous reduction and synthesis of Ni-WN and Ni-WC from their oxide mixtures

  18. Effect of mechanical activation on TiC synthesis reaction in Al-Ti-C powder mixture

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    After milling in a high-energy ball miller for various times, the synthesis reaction process of the Al-Ti-C powder mixture were investigated by difference thermal analysis (DTA) and X-ray diffractometry (XRD). According to the patterns of reaction peaks on the DTA curves, the activation energy of each reaction was calculated. The experimental results of DTA show that the synthesis reaction of Al-Ti-C powder mixture can be enhanced after high-energy milling. The longer the milling time, the lower the reaction temperature. The synthesis reaction of TiC is transformed from Ti+C→TiC to Al3Ti+C→TiC+3Al with long period milling. Meanwhile, the activation energy of the reaction reduces with increasing milling time. The effect of milling time on reduced activation energy for low temperature region is more significant than that for high temperature region.

  19. EFFECT OF FLUORINE AND CHLORINE IONS ON THE REACTION SINTERING OF MECHANICALLY ACTIVATED ZIRCON-ALUMINA MIXTURE

    Directory of Open Access Journals (Sweden)

    R. Zamani Foroshani

    2015-09-01

    Full Text Available The aim of this work was to study the effect of fluorine and chlorine ions on the formation of mullite during the reaction sintering of mechanically activated zircon-alumina powder mixture. The results showed that mechanical activation of zirconalumina powder mixture for 20 h led to grain refinement and partial amorphization. In the presence of fluorine and chlorine ions, complete formation of mullite in the mechanically activated sample occurred after 2 h of reaction sintering at 1300oC and 1400oC, respectively. In the sample lacking fluorine and chlorine ions, mullitization was not completed even after 2 h of reaction sintering at 1400oC. It was concluded that presence of fluorine and chlorine ions enhance the dissociation of zircon and formation of mullite during the reaction sintering of mechanically activated zircon-alumina mixture.

  20. 初始pH值对果糖-赖氨酸模型美拉德产物抑制香蕉酶促褐变相关性质的影响%Effect of Initial pH in a Fructose-Lysine Model System on the Properties of Maillard Reaction Products Related to the Inhibitory Effect on Banana Enzymatic Browning

    Institute of Scientific and Technical Information of China (English)

    郑杰琼; 李芬芳; 袁德保; 王必尊; 金志强; 丁武; 寇丽萍; 何应对

    2012-01-01

    This study focused on the effect of initial pH in a fructose-lysine model system on the properties of Maillard reaction products(MRPs) related to the inhibitory effect on banana enzymatic browning.MRPs were prepared through the reaction of 0.5 mol/L fructose and 0.5 mol/L lysine at a pH ranging from 2 to 11,110 ℃ for 1 h.Then,their antioxidant activity(including DPPH free radical scavenging ability and reducing power),chelating copper activity and the inhibitory effect on polyphenoloxidase banana were evaluated.The results showed that the Maillard reaction between fructose and lysine could be accelerated at alkaline conditions,however,MRPs prepared from acidic conditions(especially at pH 2 or 3),were more effective in inhibiting banana polyphenoloxidase and scavenging DPPH free radicals.The reducing power of MRPs prepared at pH 9 was highest,while those prepared at pH 2 had the lowest reducing power.Chelating copper activity of MRPs prepared at pH 2—4 or pH 11 was predominant.Generally,initial pH showed a significant effect on the efficacy of MRPs for inhibiting banana enzymatic browning,and the properties related to the inhibitory effect of MRPs prepared at different initial pHs were much different from each other,such as DPPH radical scavenging ability,reducing power,chelating copper activity and the inhibitory effect on banana polyphenoloxidase.It could also be deduced that early stage MRPs may play key roles in inhibiting banana polyphenoloxidase.%研究初始pH值对果糖-赖氨酸模型体系美拉德反应产物(MRPs)抑制香蕉酶促褐变相关性质的影响。通过调节初始pH值(2~11),于110℃条件下反应1h得到MRPs,对产物DPPH自由基清除能力、还原力、螯合Cu2+能力、抑制多酚氧化酶酶活能力进行考察。结果表明:碱性条件促使美拉德反应加剧,酸性条件MRPs能更有效抑制香蕉多酚氧化酶酶活力及清除DPPH自由基;pH9时的MRPs具有最好的还原力,而pH2时的MRPs

  1. A comparison of the Maillard reactivity of proline to other amino acids using pyrolysis-molecular beam mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Luc Moens; Robert J. Evans; Michael J. Looker; Mark R. Nimlos [National Bioenergy Center, Golden, CO (United States). National Renewable Energy Laboratory

    2004-08-01

    Maillard chemistry, or the low temperature condensation of amino acids and carbohydrates, is shown to be relevant to the practical regime of biomass pyrolysis and leads to dramatic changes in low-temperature volatile products and residual solid structure. Mixtures of amino acids and glucose were subjected to a two-temperature heating sequence (5 min each at 170 and 325{sup o}C) and the volatile products analyzed by molecular beam mass spectrometry. Significant volatile yield was observed from the mixtures at 170{sup o}C where neither amino acids nor glucose generated volatile material in the time frame studied. Proline was the most active of the amino acids studied. Volatile products at low temperature included the diketopiperazine, which were generated in higher yields than from proline alone. Also generated were Maillard condensation such as 1-(1{prime}-pyrrolidinyl)-2-propanone. These products were also generated at 325{sup o}C, but in addition, the mass spectra included evidence for the direct formation of nitrogen-containing aromatics. These observations are discussed in relation to known Maillard chemistry. 37 refs., 8 figs., 1 tab.

  2. Correlation between discrete probability and reaction front propagation rate in heterogeneous mixtures

    Science.gov (United States)

    Naine, Tarun Bharath; Gundawar, Manoj Kumar

    2017-09-01

    We demonstrate a very powerful correlation between the discrete probability of distances of neighboring cells and thermal wave propagation rate, for a system of cells spread on a one-dimensional chain. A gamma distribution is employed to model the distances of neighboring cells. In the absence of an analytical solution and the differences in ignition times of adjacent reaction cells following non-Markovian statistics, invariably the solution for thermal wave propagation rate for a one-dimensional system with randomly distributed cells is obtained by numerical simulations. However, such simulations which are based on Monte-Carlo methods require several iterations of calculations for different realizations of distribution of adjacent cells. For several one-dimensional systems, differing in the value of shaping parameter of the gamma distribution, we show that the average reaction front propagation rates obtained by a discrete probability between two limits, shows excellent agreement with those obtained numerically. With the upper limit at 1.3, the lower limit depends on the non-dimensional ignition temperature. Additionally, this approach also facilitates the prediction of burning limits of heterogeneous thermal mixtures. The proposed method completely eliminates the need for laborious, time intensive numerical calculations where the thermal wave propagation rates can now be calculated based only on macroscopic entity of discrete probability.

  3. Mechanochemical reactions and strengthening in epoxy-cast aluminum iron-oxide mixtures

    Science.gov (United States)

    Ferranti, Louis, Jr.

    2007-12-01

    Epoxy-cast Al+Fe2O3 thermite composites are an example of a structural energetic material that can simultaneously release chemical energy while providing structural strength. The structural/mechanical response and chemical reaction behavior are closely interlinked through characteristics of deformation and intermixing of reactants. In this work, the structural and energetic response of composites made from stoichiometric mixtures of nano- and micro-scale aluminum and hematite (Fe2O3) powders dispersed in 47 to 78 vol.% epoxy was investigated by characterizing the mechanical behavior under high-strain rate and shock loading conditions. The main focus of the work was to understand the influence of microstructure on mechanical behavior in epoxy-cast Al+Fe2O3 materials when exposed to high stress, large strain, and high rate loading conditions. The material's Hugoniot at pressures up to approximately 20 GPa for an Al+Fe2O3+78 vol.% epoxy composite and up to approximately 8 GPa for Al+Fe2O3+60 vol.% epoxy composite has been determined. The results reveal an inert pressure-relative volume (P-V) and shock-particle velocity (US-UP) response in the range of the shock-conditions explored, with the Al+Fe2O3+60 vol.% epoxy composite showing a greater shock stiffness. The addition of solid particle inclusions alters the Hugoniot response as compared to pure epoxy behavior. This is attributed to possible induced bulk damage that changes the composite's response as impact stress increases. While the 78 vol.% epoxy composition shows a transition from "undamaged" to "damaged" behavior that approaches pure epoxy response, the 60 vol.% epoxy composition exhibits a gradual toughening behavior. Impact experiments have also been conducted for characterizing the high-strain rate deformation and fracture response obtained from instrumented reverse Taylor tests using high-speed camera and velocity interferometry. The results show that these composite materials exhibit viscoelastic

  4. Investigation of shock-induced and shock-assisted chemical reactions in molybdenum-silicon powder mixtures

    Science.gov (United States)

    Vandersall, Kevin Stewart

    1999-10-01

    In this research, chemical reactions occurring in molybdenum and silicon powder mixtures under "shock-induced" (those occurring during the high-pressure shock state) and "shock-assisted" (those occurring subsequent to the shock event, but due to bulk temperature increases) conditions were investigated. Differences in the densities and yield strengths of the two constituents, in addition to the large heat of reaction associated with molybdenum disilicide (MoSi2) formation can lead to shock-induced as well as shock-assisted reactions, which make this an ideal system to delineate the kinetics and mechanisms of reactions occurring in shock-compressed powder mixtures. Shock recovery experiments performed on Mo + 2 Si powder mixtures employing cylindrical implosion geometry showed thermally initiated reactions. A mixed phase eutectic type microstructure of MoSi2 and Mo 5Si3, resulting from reaction occurring due to melting of both reactants, was observed in axial regions of the cylindrical compacts. In regions surrounding the mach stem, melting of only silicon and reaction occurring via dissolution and re-precipitation forming MoSi2 spherules surrounding molybdenum particles in a melted and solidified silicon matrix was observed. The planar pressure shock recovery geometry showed a single phase MoSi2, microstructure formed due to a solid-state pressure-induced reaction process. The time-resolved instrumented experiments were performed using a single stage gas gun in the velocity range of 500 m/s to 1 km/s, and employed poly-vinyl di-flouride (PVDF) stress gauges placed at the front and rear surfaces of the powder to determine the crush strength, densification history, and reaction initiation threshold conditions. Time-resolved experiments performed on ˜58% dense Mo + 2 Si powder mixtures at input stresses less than 4 GPa, showed characteristics of powder densification and dispersed propagated wave stress profiles with rise time >˜40 nanoseconds. At input stress between

  5. GC-MS结合电子鼻分析温度对肉味香精风味品质的影响%Effect of Temperature on Sensory and Flavor Characteristics of Maillard Reaction Products Derived from Bovine Bone Hydrolsate as Analyzed by GC-MS and Electronic Sensor

    Institute of Scientific and Technical Information of China (English)

    李迎楠; 刘文营; 成晓瑜

    2016-01-01

    The effect of different reaction temperatures on sensory quality and volatile flavor compounds of Maillard reaction products (MRPs) derived from bovine bone hydrolysate was determined by gas chromatography-mass spectrometry (GC-MS) and electronic nose. The results showed that MRPs generated at different temperatures exhibited high variability in sensory quality and volatile flavor. The meat flavor produced at 105℃had obvious advantages in the terms of flavor and taste. In the meantime, it contained much more volatile flavor substances, which could reach 93.62%as detected by GC-MS. In particular, pyrazine compounds as characteristic flavor components accounted for 8.19%. The contents of aldehydes and ketones were higher as well. The meat flavor manufactured under this condition was dark brown, and had full bodied fragrance and a lasting aftertaste. At the same time, electronic nose analysis revealed that products obtained at different reaction temperatures had significant differences in volatile flavor composition.%以肉味香精为研究对象,从感官品质、挥发性风味物质组成和电子鼻分析角度研究不同反应温度对其风味品质的影响。结果表明,不同温度条件下肉味香精在感官评价、挥发性风味物质等方面都有较大的差异性。105℃条件下的肉味香精产品风味和口感相对较好;经气相色谱-质谱联用仪分析,该条件得到的肉味香精中挥发性物质相对含量较高,达到93.62%,其中具有特征风味的吡嗪类化合物高达8.19%,醛、酮类化合物的相对含量较高;在此条件下得到的肉味香精,色泽呈现深褐色,香味浓郁,回味悠长。运用电子鼻技术分析发现,不同温度条件下样品存在显著性差异,风味有所改变。

  6. Influence of Free Amino Acids, Oligopeptides, and Polypeptides on the Formation of Pyrazines in Maillard Model Systems.

    Science.gov (United States)

    Scalone, Gustavo Luis Leonardo; Cucu, Tatiana; De Kimpe, Norbert; De Meulenaer, Bruno

    2015-06-10

    Pyrazines are specific Maillard reaction compounds known to contribute to the unique aroma of many products. Most studies concerning the generation of pyrazines in the Maillard reaction have focused on amino acids, while little information is available on the impact of peptides and proteins. The present study investigated the generation of pyrazines in model systems containing whey protein, hydrolyzed whey protein, amino acids, and glucose. The impact of thermal conditions, ratio of reagents, and water activity (a(w)) on pyrazine formation was measured by headspace solid-phase microextraction with gas chromatography/mass spectrometry (HS-SPME-GC/MS. The presence of oligopeptides from hydrolyzed whey protein contributed significantly to an increased amount of pyrazines, while in contrast free amino acids generated during protein hydrolysis contributed to a lesser extent. The generation of pyrazines was enhanced at low a(w) (0.33) and high temperatures (>120 °C). This study showed that the role of peptides in the generation of pyrazines in Maillard reaction systems has been dramatically underestimated.

  7. 牛骨酶解物对制备牛肉香精中挥发性风味成分的影响%Effect of Addition of Enzymatic Hydrolysate of Bovine Bone into Maillard Reaction System on Volatile Aroma Composition of Beef Essence

    Institute of Scientific and Technical Information of China (English)

    成晓瑜; 李迎楠; 刘文营; 贾晓云

    2016-01-01

    This study was intended to examine the effect of adding different amounts of bovine bone collagen hydrolysate prepared with flavourzyme to the Maillard reaction system used to produce beef essence on the flavor quality of reaction products. The results showed that the volatile flavor compounds of beef essence varied significantly depending on the amount of added bovine bone collagen hydrolysate. The addition of 6 g of bovine bone collagen hydrolysate led to the generation of high amounts of volatile compounds (95.39%) in the beef essence, with the characteristic flavor compounds pyrazines, aldehydes and ketones being dominant. Electronic nose analysis suggested that the flavor compounds formed in the presence of 8 and 10 g of the hydrolysate were partly identical, and significant differences were found at other addition levels of the hydrolysate. The beef essence obtained under this condition had an outstanding roast aroma and good flavor.%以牛肉香精为研究对象,从挥发性风味物质组成和电子鼻分析角度研究不同牛骨酶解物添加量对其风味品质的影响。结果表明:不同牛骨酶解物添加量使牛肉香精在风味物质方面有较大的差异性。牛骨酶解物添加量为6 g时,牛肉香精中挥发性物质含量较高,达到95.39%,其中具有特征风味的吡嗪类、醛类、酮类化合物的含量相对较高;运用电子鼻技术分析发现,除添加量为8 g和10 g时有部分重叠,其余条件下样品存在显著性差异。在此条件下得到的牛肉香精烤香味较为明显,具有良好的风味香气。

  8. Theoretical analysis of co-solvent effect on the proton transfer reaction of glycine in a water-acetonitrile mixture.

    Science.gov (United States)

    Kasai, Yukako; Yoshida, Norio; Nakano, Haruyuki

    2015-05-28

    The co-solvent effect on the proton transfer reaction of glycine in a water-acetonitrile mixture was examined using the reference interaction-site model self-consistent field theory. The free energy profiles of the proton transfer reaction of glycine between the carboxyl oxygen and amino nitrogen were computed in a water-acetonitrile mixture solvent at various molar fractions. Two types of reactions, the intramolecular proton transfer and water-mediated proton transfer, were considered. In both types of the reactions, a similar tendency was observed. In the pure water solvent, the zwitterionic form, where the carboxyl oxygen is deprotonated while the amino nitrogen is protonated, is more stable than the neutral form. The reaction free energy is -10.6 kcal mol(-1). On the other hand, in the pure acetonitrile solvent, glycine takes only the neutral form. The reaction free energy from the neutral to zwitterionic form gradually increases with increasing acetonitrile concentration, and in an equally mixed solvent, the zwitterionic and neutral forms are almost isoenergetic, with a difference of only 0.3 kcal mol(-1). The free energy component analysis based on the thermodynamic cycle of the reaction also revealed that the free energy change of the neutral form is insensitive to the change of solvent environment but the zwitterionic form shows drastic changes. In particular, the excess chemical potential, one of the components of the solvation free energy, is dominant and contributes to the stabilization of the zwitterionic form.

  9. Influence of thermally processed carbohydrate/amino acid mixtures on the fermentation by Saccharomyces cerevisiae.

    Science.gov (United States)

    Tauer, Andreas; Elss, Sandra; Frischmann, Matthias; Tellez, Patricia; Pischetsrieder, Monika

    2004-04-07

    The production of alcoholic beverages such as Tequila, Mezcal, whiskey, or beer includes the fermentation of a mash containing Maillard reaction products. Because excessive heating of the mash can lead to complications during the following fermentation step, the impact of Maillard products on the metabolism of Saccharomyces cerevisiae was investigated. For this purpose, fermentation was carried out in a model system in the presence and absence of Maillard reaction products and formation of ethanol served as a marker for the progression of fermentation. We found that increasing amounts of Maillard products reduced the formation of ethanol up to 80%. This effect was dependent on the pH value during the Maillard reaction, reaction time, as well as the carbohydrate and amino acid component used for the generation of Maillard reaction products. Another important factor is the pH value during fermentation: The inhibitory effect of Maillard products was not detectable at a pH of 4 and increased with higher pH-values. These findings might be of relevance for the production of above-mentioned beverages.

  10. Impact of parboiling conditions on Maillard precursors and indicators in long-grain rice cultivars.

    Science.gov (United States)

    Lamberts, Lieve; Rombouts, Ine; Brijs, Kristof; Gebruers, Kurt; Delcour, Jan A

    2008-10-15

    The effect of steaming conditions (mild, intermediate and severe) during parboiling of five different long-grain rice cultivars (brown rice cultivars Puntal, Cocodrie, XL8 and Jacinto, and a red rice) on rice colour, and Maillard precursors and indicators was investigated. Rice colour increased with severity of parboiling conditions. Redness increased more than yellowness when parboiling brown rice. Parboiling turned red rice black. It changed the levels of glucose, fructose, sucrose, and maltose. Losses of the non-reducing sugar, sucrose were caused by both leaching into the soaking water and enzymic conversion, rather than by thermal degradation during steaming. Concentrations of the reducing sugars, glucose and fructose, in intermediately parboiled rice were higher than those of mildly parboiled rice. After severe parboiling, glucose levels were lower than those of intermediately parboiled rice, while fructose levels were higher. These changes were ascribed to the sum of losses in the Maillard reaction (MR), formations as a result of starch degradation and isomerisation of glucose into fructose. It was clear that the ε-amino group of protein-bound lysine was more affected by parboiling conditions and loss in MRs, than that of free lysine. Low values of the MR indicators furosine and free 5-hydroxymethyl-2-furaldehyde (HMF) in processed brown and red rices were related to mild parboiling, whereas high furosine and low free HMF levels were indicative of rices being subjected to intermediate processing conditions. High furosine and high free HMF contents corresponded to severe hydrothermal treatments. The strong correlation (r=0.89) between the free HMF levels and the increase in redness of parboiled brown rices suggested that Maillard browning was reflected more in the red than in the yellow colour.

  11. Investigating by EPR the reaction processes of intermediate products from the thermodestruction of binary mixtures of coals

    Energy Technology Data Exchange (ETDEWEB)

    Ikonomopulo, V.P.

    1983-03-01

    Binary mixtures of long-flame, gas-bituminous, coking, lean-caking, and lean coals are used to study the processes for the interaction of intermediate products of the thermodestruction of coals. The value and sign of the paramagnetic effect which occurs during simultaneous heating of coals in a binary mixture are determined by the relative position of each coal on the metamorphic scale. The possible role of plastification and reaction of the two coals in the formation of an ordered paramagnetic structure are demonstrated. 4 references.

  12. Inhibitory effect of glucosamine-cysteine maillard reaction product on tyrosinase%虾蟹壳氨基葡萄糖-半胱氨酸美拉德反应产物对酪氨酸酶的抑制作用

    Institute of Scientific and Technical Information of China (English)

    林晓彰; 刘必谦; 周湘池; 章思思; 庄怡

    2014-01-01

    为了探讨半胱氨酸-氨糖美拉德反应产物(GCMRPs)对酪氨酸酶催化活性的影响及其在对虾冷藏保鲜中的作用,以半胱氨酸及虾蟹壳氨基葡萄糖盐酸盐为原料,在碱性条件下(pH=10)制备美拉德反应产物,并分别测定其酪氨酸酶二酚酶活抑制能力及对南美白对虾黑变腐败的影响。结果显示, GCMRPs 具有很强的二酚酶活抑制能力,对酪氨酸酶二酚酶活的抑制类型为不可逆的竞争性抑制。通过比较,在同浓度下,其抑制酪氨酸酶二酚酶活能力比半胱氨酸、曲酸更为优越,可做为一种有效的酶抑制剂。同时,鲜虾保鲜实验显示该产物有很好的防止黑变的能力,且有一定的防腐能力。%Research on tyrosinase inhibitors has become a common concern due to the important role of tyrosinase both in mammalian melanogenesis and fruit or shrimp enzymatic browning. In this paper, Maillard reaction prod-ucts prepared by heating glucosamine hydrochloride-cysteine model in alkaline condition (GCMRPs) were studied for their tyrosinase inhibition activity and effect on quality of shrimp during ice-storage. The results showed that, this compound was an irreversible competitive inhibitor exhibiting a higher inhibitory effect than cysteine and kojic acid at the same concentration. In addition, the effect of GCMRPs on quality of pacific white shrimp during ice-storage was investigated. Shrimp treated with 20 mmol/L GCMRPs exhibited lower melanosis score and total viable count compared with those without treatment throughout the storage period.

  13. Evaluation of the kinetic and thermodynamic parameters of oxidation reaction in biodiesel from a quaternary mixture of raw material

    Directory of Open Access Journals (Sweden)

    Karina Gomes Angilelli

    2017-05-01

    Full Text Available A mixture of vegetable oil and animal fat as raw materials was optimized by simplex-centroid mixture design to produce a type of biodiesel with good oxidative stability, flow properties and reaction yield. Further, kinetic and thermodynamic parameters of oxidation reaction were determined by the accelerated method at different temperatures. Biodiesel produced with sodium methoxide as catalyst presented 6.5°C of cloud point, 2.0°C of pour point, and oxidative stability at 110°C equal to 8.98h, with a reaction yield of 96.04%. Activation energy of the oxidation reaction was 81.03 kJ mol-1 for biodiesel produced with sodium hydroxide and 90.51 kJ mol-1 for sodium methoxide. The positive values for DH‡ and DG‡ indicate that the oxidation process is endothermic and endergonic. The less negative DS‡ for biodiesel produced with sodium methoxide (-28.87 JK-1 mol-1 showed that the process of degradation of this biofuel was slower than that produced with NaOH. The mixture of raw materials proposed, transesterified with the methoxide catalyst, resulted in a biofuel that resisted oxidation for longer periods, making unnecessary the addition of antioxidant

  14. Fluid phase equilibria of the reaction mixture during the selective hydrogenation of 2-butenal in dense carbon dioxide

    DEFF Research Database (Denmark)

    Musko, Nikolai; Jensen, Anker Degn; Baiker, Alfons

    2012-01-01

    vapour–liquid or liquid–liquid equilibria data available in the literature. No experimental data for the CO2–2-butenal binary system were available in the literature; therefore, the bubble points of this mixture of varying composition at three different temperatures were measured in a high-pressure view...... cell. The results of the catalytic experiments showed that small amounts of carbon dioxide added to the system significantly decrease the conversion, whereas at higher loadings of CO2 the reaction rate gradually increases reaching a maximum. The CPA calculations revealed that this maximum is achieved...... in the so-called “expanded liquid” region, which is located near the critical point of the reacting mixture. It was also found that in this point the hydrogen concentration achieved its maximum in the CO2-expanded phase. Furthermore, the pressure – temperature regions where the multicomponent reaction...

  15. Temperature Non-Homogeneieties in a Catalytic Reactor With a Periodic Change in the Direction of the Reaction Mixture Feed

    Directory of Open Access Journals (Sweden)

    Zheleva Ivanka

    2015-06-01

    Full Text Available Temperature non-homogeneities in a catalytic reactor with periodic change in the direction of the reaction mixture feed is investigated in the present work. The temperature of the reaction mixture is described using a numerical algorithm for simulation of the work of the catalytic reactor, graphically shown and commented. The influence of the higher catalyst layer porosity in the wall area upon the temperature distribution in the reactor is studied. The existence of two different regimes is shown - a high temperature one in the middle part of the layer and a low temperature one in the high porosity area of the layer in contact with the reactor wall. This leads to not very effective usage of the catalyst in these parts of the catalyst layer in the reactor. This simulation can be used for better understanding and controlling of the examined catalytic process.

  16. Direct Energy Supply to the Reaction Mixture during Microwave-Assisted Hydrothermal and Combustion Synthesis of Inorganic Materials

    Directory of Open Access Journals (Sweden)

    Roberto Rosa

    2014-05-01

    Full Text Available The use of microwaves to perform inorganic synthesis allows the direct transfer of electromagnetic energy inside the reaction mixture, independently of the temperature manifested therein. The conversion of microwave (MW radiation into heat is useful in overcoming the activation energy barriers associated with chemical transformations, but the use of microwaves can be further extended to higher temperatures, thus creating unusual high-energy environments. In devising synthetic methodologies to engineered nanomaterials, hydrothermal synthesis and solution combustion synthesis can be used as reference systems to illustrate effects related to microwave irradiation. In the first case, energy is transferred to the entire reaction volume, causing a homogeneous temperature rise within a closed vessel in a few minutes, hence assuring uniform crystal growth at the nanometer scale. In the second case, strong exothermic combustion syntheses can benefit from the application of microwaves to convey energy to the reaction not only during the ignition step, but also while it is occurring and even after its completion. In both approaches, however, the direct interaction of microwaves with the reaction mixture can lead to practically gradient-less heating profiles, on the basis of which the main observed characteristics and properties of the aforementioned reactions and products can be explained.

  17. Modes of reaction front propagation and end-gas combustion of hydrogen/air mixtures in a closed chamber

    KAUST Repository

    Shi, Xian

    2017-01-05

    Modes of reaction front propagation and end-gas combustion of hydrogen/air mixtures in a closed chamber are numerically investigated using an 1-D unsteady, shock-capturing, compressible and reacting flow solver. Different combinations of reaction front propagation and end-gas combustion modes are observed, i.e., 1) deflagration without end-gas combustion, 2) deflagration to end-gas autoignition, 3) deflagration to end-gas detonation, 4) developing or developed detonation, occurring in the sequence of increasing initial temperatures. Effects of ignition location and chamber size are evaluated: the asymmetric ignition is found to promote the reactivity of unburnt mixture compared to ignitions at center/wall, due to additional heating from asymmetric pressure waves. End-gas combustion occurs earlier in smaller chambers, where end-gas temperature rise due to compression heating from the deflagration is faster. According to the ξ−ε regime diagram based on Zeldovich theory, modes of reaction front propagation are primarily determined by reactivity gradients introduced by initial ignition, while modes of end-gas combustion are influenced by the total amount of unburnt mixture at the time when autoignition occurs. A transient reactivity gradient method is provided and able to capture the occurrence of detonation.

  18. Physicochemical analysis and nonisothermal kinetic study of sertraline–lactose binary mixtures

    Directory of Open Access Journals (Sweden)

    Faranak Ghaderi

    2017-07-01

    Full Text Available In the present study the physicochemical stability of sertraline with lactose was evaluated in drug-excipient binary mixtures. Different physicochemical methods such as differential scanning calorimetry (DSC, Fourier-transform infrared spectroscopy, and mass spectrometry were applied to confirm the incompatibility. The final aim of this study was to evaluate the kinetic parameters using a fast and sensitive DSC method. Solid-state kinetic parameters were derived from nonisothermally stressed physical mixtures using different thermal models such as Friedman, Flynn–Wall–Ozawa, and Kissinger–Akahira–Sunose. Overall, the instability of sertraline with lactose was successfully evaluated. Further confirmation was made by tracking the Maillard reaction product of sertraline and lactose by mass spectrometry. DSC scans provided important information about the stability of sertraline in solid-state condition and also revealed the related thermokinetic parameters in order to understand the nature of the chemical instability.

  19. Covalently Immobilized Laccase for Decolourization of Glucose-Glycine Maillard Products as Colourant of Distillery Wastewater.

    Science.gov (United States)

    Singh, Nimisha; Basu, Subhankar; Vankelecom, Ivo F J; Balakrishnan, Malini

    2015-09-01

    Maillard reaction products like melanoidins are recalcitrant, high-molecular-weight compounds responsible for colour in sugarcane molasses distillery wastewater. Conventional biological treatment is unable to break down melanoidins, but extracellular laccase and manganese peroxidase of microbial origin can degrade these complex molecules. In this work, laccase was covalently immobilized on alumina pellets activated with aminopropyltriethoxysilane (APTES). The immobilization yield was 50-60 %, and the enzyme activity (886 U/L) was 5-fold higher compared to the soluble enzyme (176 U/L). The immobilized enzyme also showed higher tolerance to pH (4-6) and temperature (35-60 °C), as well as improved storage stability (49 days) and operational stability (10 cycles). Degradation of glucose-glycine Maillard products using immobilized laccase led to 47 % decolourization in 6 h at pH 4.5 and 28 °C. A comprehensive treatment scheme integrating enzymatic, microbial and membrane filtration steps resulted in 90 % decolourization.

  20. Maillard reaction induces changes in saccharides and amino acids ...

    African Journals Online (AJOL)

    Mei-Bian Hu, Wei Peng, Yu-Jie Liu, Dan Yan, Xi Chen, Chun-Jie Wu*. College of Pharmacy ... extracted with 80 % ethanol for 3 h to remove colored materials. ..... Xu M, Yang SL, Peng W, Liu YJ, Xie DS, Li XY, WU CJ. A Novel Method for the ...

  1. A Study on Reactions of Carbon-Carbonate Mixture at Elevated Temperature : As an Anode Media of SO-DCFC

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Jun Ho; Kang, Kyungtae; Hwang, Jun Young [Korea Institute of Industrial Technoloy, Cheonan (Korea, Republic of)

    2014-08-15

    A direct carbon fuel cell (DCFC) generates electricity directly by converting the chemical energy in coal. In particular, a DCFC system with a solid oxide electrolyte and molten carbonate anode media has been proposed by SRI. In this system, however, there are conflicting effects of temperature, which enhances the ion conductivity of the solid electrolyte and reactivity at the electrodes while causing a stability problem for the anode media. In this study, the effect of temperature on the stability of a carbon-carbonate mixture was investigated experimentally. TGA analysis was conducted under either nitrogen or carbon dioxide ambient for Li{sub 2} CO{sub 3}, K{sub 2} CO{sub 3}, and their mixtures with carbon black. The composition of the exit gas was also monitored during temperature elevation. A simplified reaction model was suggested by considering the decomposition of carbonates and the catalyzed Boudouard reactions. The suggested model could well explain both the measured weight loss of the mixture and the gas formation from it.

  2. Effect of an essential oil mixture on skin reactions in women undergoing radiotherapy for breast cancer: a pilot study.

    Science.gov (United States)

    Halm, Margo A; Baker, Clarice; Harshe, Val

    2014-12-01

    This pilot study compared the effects of an essential oil mixture versus standard care on skin reactions in breast cancer patients receiving radiation. Using an experimental design, 24 patients were randomized to standard care (i.e., RadiaPlexRx™ ointment) or an essential oil mixture. Products were applied topically three times a day until 1 month postradiation. Weekly skin assessments were recorded and women completed patient satisfaction and quality of life (QOL) instruments at 3-, 6-, and 10-week intervals. No significant differences were found for skin, QOL, or patient satisfaction at interim or follow-up time points. Effect sizes were as follows: skin = .01 to .07 (small-medium effect); QOL = .01 to .04 (small effect); patient satisfaction = .02 (small effect). The essential oil mixture did not provide a better skin protectant effect than standard care. These findings suggest the essential oil mixture is equivalent to RadiaPlexRx, a common product used as standard care since it has been shown to be effective in protecting skin from radiation. Thus, this pilot provides evidence to support botanical or nonpharmaceutical options for women during radiotherapy for breast cancer. © The Author(s) 2014.

  3. Binding Reaction of Hemin with Chloroquine, Quinine and Quinidine in Water-propylene Glycol Mixture

    Institute of Scientific and Technical Information of China (English)

    MAVAKALA,B.K; NLANDU,B.B.; MPIANA,P.T.; GUSHIMANA,Z.Y.; 尉志武

    2003-01-01

    the interaction of hemin with chloroquine,quinine and quinidine was investigated in 50% water-propylene glycol mixture at pH=9,8.1,7.4 and 6.8using a spectrophotometric method.The data could be well fitted into a model consistent with the formation of a 1:1 complex between the reacting partners.In addition,the results indicated that hemin complexed more strongly with quinidine than with chloroquine and quinine,and the binding constants were pH-dependent.Moreover,it was proved that the water-propylene glycol mixture is well suitable to the study of the systems containing hemin and quinolinebased drugs.

  4. Reaction mechanism for the thermal decomposition of BCl3/CH4/H2 gas mixtures.

    Science.gov (United States)

    Reinisch, Guillaume; Vignoles, Gérard L; Leyssale, Jean-Marc

    2011-10-27

    This paper presents an ab initio study of the B/C/Cl/H gas phase mechanism, featuring 10 addition-elimination reactions involving BH(i)Cl(j) (i + j ≤ 3) species and a first description of the chemical interaction between the carbon-containing and boron-containing subsystems through the three reactions BCl(3) + CH(4) ⇌ BCl(2)CH(3) + HCl, BHCl(2) + CH(4) ⇌ BCl(2)CH(3) + H(2), and BCl(2) + CH(4) ⇌ BHCl(2) + CH(3). A reaction mechanism is then proposed and used to perform some illustrative equilibrium and kinetic calculations in the context of chemical vapor deposition (CVD) of boron carbide. Our results show that the new addition-elimination reaction paths play a crucial role by lowering considerably the activation barrier with respect to previous theoretical evaluations; they also confirm that BCl(2)CH(3) is an important species in the mechanism.

  5. SUBSTITUTION REACTION OF HYDROXY OF CITRONELLOL WITH CHLORIDE USING A MIXTURE OF AMMONIUM CHLORIDE AND SULPHURIC ACID

    Directory of Open Access Journals (Sweden)

    Endah Sayekti

    2016-08-01

    Full Text Available Substitution reaction of hydroxy of citronellol with chloride using a mixture of ammonium chloride (NH4Cl and sulphuric acid (H2SO4 has been conducted. The citronellol was obtained from the reduction of citronellal using sodium borohydride (NaBH4 at room temperature for 30 minutes. Substitution of hydroxy of citronellol with chloride ion was carried out at 80 oC and molarity ratio of citronellol and NH4Cl 1:1, 1:2; 1:3; and 1:4 respectively. Identification of the product by gas chromatography-mass spectrometry (GC-MS showed that the substitution reaction produced 2-isopropyl-5-methyl-1-chlorocyclohexane compound with rendemen 64,49 % in mol ratio of 1:4. The infra red (IR analysis showed that there was a vibration at wave number 763 cm-1 which is a typical C-Cl vibrations.

  6. Reaction of cocksfoot (Dactylis glomerata L. in grass-clover mixture on N fertilization and grazing

    Directory of Open Access Journals (Sweden)

    Marcela Andreata-Koren

    2009-09-01

    Full Text Available Grazing is the most common way of using a hill and mountain areas because of their specific agro-ecological conditions. Cocksfoot is a grass with high productivity and quality, and it is very good for sowing in the sward for grazing. Because of its good adaptability to different growing conditions, especially in very dry and cold areas, it is excellent in relation to some other good grasses, which can not be raised in such areas. The aim of the experiment was to determine effect of N application (0-N0 and 150 kg ha-1 year-1-N150 and rotational grazing by cattle (C and sheep (S, and their interaction on the cocksfoot sown in a mixture of smooth-stalked meadow grass (Poa pratensis L. and white clover (Trifolium repens L. in hill mountain areas. In a three-year average, the application of 150 kg ha-1 N had significant impact on cocksfoot population density (number of tillers m-2, and it was 51.4 % higher than the recorded one before grazing (P<0.05 and 42.2 % higher after grazing (P<0.01 in comparison to N0. The application of 150 kg ha-1 N resulted in significantly higher cocksfoot dry matter (DM yield for 38.6 % (P<0.01 and 15.3 % higher cocksfoot share in the total mixture in relation to N0 (P<0.01. Grazing management and grazing management interaction with N rate did not significantly affect the population density of individual years. However, in the three-year average, grazing management significantly affected cocksfoot DM (P<0.01 and its percentage in the total DM mixture (P<0.01. Cattle grazing resulted in 9.9 % higher cocksfoot DM yield and 15.2 % higher cocksfoot percentage in pasture. Interaction of grazing management and N-level had significant influence on the percentage of cocksfoot DM in grass-clover mixture. On cattle grazed areas fertilized with 150 kg ha-1 N, the percentage of cocksfoot DM was the highest (74. 07%, while the lowest percentage of cocksfoot DM was recorded on the sheep grazed areas without N (55.12%.

  7. On the solid–liquid phase diagrams of binary mixtures of even saturated fatty alcohols: Systems exhibiting peritectic reaction

    Energy Technology Data Exchange (ETDEWEB)

    Carareto, Natália D.D. [EXTRAE, Department of Food Engineering, Food Engineering Faculty, University of Campinas, UNICAMP, CEP 13083-862 Campinas, SP (Brazil); Santos, Adenílson O. dos [Social Sciences, Health and Technology Center, University of Maranhão, UFMA, CEP 65900-410 Imperatriz, MA (Brazil); Rolemberg, Marlus P. [Institute of Science and Technology, University of Alfenas, UNIFAL, Rodovia José AurélioVilela, CEP 37715400 Poços de Caldas, MG (Brazil); Cardoso, Lisandro P. [Institute of Physics GlebWataghin, University of Campinas, UNICAMP, C.P. 6165, CEP 13083-970 Campinas, SP (Brazil); Costa, Mariana C. [School of Applied Science, University of Campinas, UNICAMP, CEP 13484-350 Limeira, SP (Brazil); Meirelles, Antonio J.A., E-mail: tomze@fea.unicamp.br [EXTRAE, Department of Food Engineering, Food Engineering Faculty, University of Campinas, UNICAMP, CEP 13083-862 Campinas, SP (Brazil)

    2014-08-10

    Highlights: • SLE of binary mixtures of saturated fatty alcohols was studied. • Experimental data were obtained using DSC and stepscan DSC. • Microscopy and X-ray diffraction used as complementary techniques. • Systems presented eutectic, peritectic and metatectic points. - Abstract: The solid–liquid phase diagrams of the following binary mixtures of even saturated fatty alcohols are reported in the literature for the first time: 1-octanol (C8OH) + 1-decanol (C10OH), 1-decanol + 1-dodecanol (C12OH), 1-dodecanol + 1-hexadecanol (C16OH) and 1-tetradecanol (C14OH) + 1-octadecanol (C18OH). The phase diagrams were obtained by differential scanning calorimetry (DSC) using a linear heating rate of 1 K min{sup −1} and further investigated by using a stepscan DSC method. X-ray diffraction (XRD) and polarized light microscopy were also used to complement the characterization of the phase diagrams which have shown a complex global behavior, presenting not only peritectic and eutectic reactions, but also the metatectic reaction and partial immiscibility on solid state.

  8. Reaction Pathways in Catechol/Primary Amine Mixtures: A Window on Crosslinking Chemistry

    Science.gov (United States)

    Yang, Juan; Saggiomo, Vittorio; Velders, Aldrik H.; Cohen Stuart, Martien A.; Kamperman, Marleen

    2016-01-01

    Catechol chemistry is used as a crosslinking tool abundantly in both natural organisms (e.g. mussels, sandcastle worms) and synthetic systems to achieve the desired mechanical properties. Despite this abundance and success, the crosslinking chemistry is still poorly understood. In this study, to simplify the system, yet to capture the essential chemistry, model compounds 4-methyl catechol and propylamine are used. The reaction of 4-methyl catechol (2 mM) with propylamine (6 mM) is carried out in the presence of NaIO4 (2 mM) in 10 mM Na2CO3 aqueous solution. A variety of spectroscopic/spectrometric and chromatographic methods such as 1H NMR, LC-MS, and UV-VIS are used to track the reaction and identify the products/intermediates. It is found that the crosslinking chemistry of a catechol and an amine is both fast and complicated. Within five minutes, more than 60 products are formed. These products encompass 19 different masses ranging from molecular weight of 179 to 704. By combining time-dependent data, it is inferred that the dominant reaction pathways: the majority is formed via aryloxyl-phenol coupling and Michael-type addition, whereas a small fraction of products is formed via Schiff base reactions. PMID:27930671

  9. Sequence Analysis of Trimer Isomers Formed by Montmorillonite Catalysis in the Reaction of Binary Monomer Mixtures

    Science.gov (United States)

    Ertem, Gözen; Hazen, Robert M.; Dworkin, Jason P.

    2007-10-01

    Oligonucleotides are structurally similar to short RNA strands. Therefore, their formation via non-enzymatic reactions is highly relevant to Gilbert's RNA world scenario (1986) and the origin of life. In laboratory synthesis of oligonucleotides from monomers, it is necessary to remove the water molecules from the reaction medium to shift the equilibrium in favor of oligonucleotide formation, which would have been impossible for reactions that took place in dilute solutions on the early Earth. Model studies designed to address this problem demonstrate that montmorillonite, a phyllosilicate common on Earth and identified on Mars, efficiently catalyzes phosphodiester-bond formation between activated mononucleotides in dilute solutions and produces RNA-like oligomers. The purpose of this study was to examine the sequences and regiospecificity of trimer isomers formed in the reaction of 5'-phosphorimidazolides of adenosine and uridine. Results demonstrated that regiospecificity and sequence specificity observed in the dimer fractions are conserved in their elongation products. With regard to regiospecificity, 61% of the linkages were found to be RNA-like 3',5'-phosphodiester bonds. With regard to sequence specificity, we found that 88% of the linear trimers were hetero-isomers with 61% A-monomer and 39% U-monomer incorporation. These results lend support to Bernal's hypothesis that minerals may have played a significant role in the chemical processes that led to the origin of life by catalyzing the formation of phosphodiester bonds in RNA-like oligomers.

  10. Antioxidant activity of bovine alpha lactalbumin Maillard products and evaluation of their in vitro gastro-duodenal digestive proteolysis.

    Science.gov (United States)

    Joubran, Yousef; Moscovici, Alice; Lesmes, Uri

    2015-04-01

    Food processing offers various pathways to tailor food functionality and digestibility. This work sought to study the impact of thermally-induced Maillard reaction between bovine alpha-lactalbumin (α-la) and fructose or fructo-oligosacchrides on physicochemical properties, antioxidant capacity and in vitro digestive fate under simulated adult and infant conditions. Colloidal stability (measured by DLS) was decreased as a result of the Maillard glycation, while antioxidant capacity (determined by FRAP) and surface hydrophobicity (H0 measurements) were elevated. Semi-dynamic in vitro digestion of Maillard conjugates revealed a mixed trend as a result of postulated competing effects of glycation on α-la's susceptibility to proteolysis; steric hindrance accompanied by protein unfolding could hinder or promote the availability of enzymatic cleavage sites. Results also showed thermal processing altered the digestive breakdown profile of α-la under infant conditions contrary to negligible effects observed under adult conditions. Evaluation of the antioxidant capacity during digestion (via DPPH assay) revealed that adult digesta possessed increased antioxidant activity throughout the gastric phase compared to infant digesta, whereas infant digesta of conjugates exhibited an increase in antioxidant capacity in the duodenum compared to adult. Moreover, during infant digestion of conjugates, an increase in antioxidant capacity was observed in the later stages of the digestion. Overall, this work demonstrates that controlled thermal processing of bovine α-la could potentially modulate its functionality and digestibility, particularly as it pertains to its ability to interfere with oxidative reactions in the lumen, possibly through the generation of bioactive peptides.

  11. Positron Spur Reactions with Excess Electrons and Anions in Liquid Organic Mixtures of Electron Acceptors

    DEFF Research Database (Denmark)

    Lévay, B.; Mogensen, O. E.

    1980-01-01

    By means of the positron lifetime technique we have measured positronium (Ps) yields in mixtures of nonpolar liquids with various electron scavengers which bind the electron fairly weakly (1–2 eV) in stable anions. The results are discussed with reference to recent excess electron works, and new...... the minimum was shifted towards the lower concentrations, which might be explained by some overlap of the energy levels on CS2 and SF6. Antiinhibition effect of C6F6 and CS2 was studied in 0.05 M CCl4/hexane solutions. In the CS2 case first a small minimum appeared in the Ps yield versus CS2 concentration...

  12. Behavior of reaction mixtures under microwave conditions: Use of sodium salts in microwave-induced N-[[sup 18]F]fluoroalkylations of aporphine and tetralin derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Zijlstra, S.; de Groot, T.J.; Kok, L.P.; Visser, G.M.; Vaalburg, W. (Univ. Hospital, Oostersingel, Groningen (Netherlands) Univ. of Groningen (Netherlands))

    1993-03-26

    In the present study, the authors have examined the behavior of reaction mixtures in a microwave field and the use of sodium salts to manipultate reaction rates. Three potential dopamine D[sub 2] agonists 2-[N-(3-[[sup 18]F]fluoropropyl)-N-[(4-fluorophenyl)ethyl]amino]-5-methoxytetralin (2), 6-(2-[[sup 18F

  13. Far-ultraviolet signatures of the 3He(n,tp) reaction in noble gas mixtures

    CERN Document Server

    Hughes, Patrick P; Thompson, Alan K; Vest, Robert E; Clark, Charles W

    2010-01-01

    Previous work showed that the 3He(n,tp) reaction in a cell of 3He at atmospheric pressure generated tens of far-ultraviolet photons per reacted neutron. Here we report amplification of that signal by factors of 1000 and more when noble gases are added to the cell. Calibrated filter-detector measurements show that this large signal is due to noble-gas excimer emissions, and that the nuclear reaction energy is converted to far-ultraviolet radiation with efficiencies of up to 30%. The results have been placed on an absolute scale through calibrations at the NIST SURF III synchrotron. They suggest possibilities for high-efficiency neutron detectors as an alternative to existing proportional counters.

  14. A Simple and Inexpensive Device for Slow, Controlled Addition of a Solution to a Reaction Mixture

    Science.gov (United States)

    Osvath, Peter

    1995-07-01

    A number of reactions require the slow and controlled addition of a solution containing one reagent to another. Attempting to control the flow rate over a number of hours using a conventional constant pressure addition funnel is a frustrating exercise; commercially available constant volume addition funnels are expensive and must be adjusted by trial and error each time a reaction is carried out. The use of an (expensive) peristaltic pump or syringe pump overcomes these problems but can introduce other complications. We have recently had occasion to carry out the synthesis of thioether macrocycles and cages requiring the slow and controlled addition of DMF solutions of (offensively odoriferous) thiols or (air-sensitive) thiolates to a reactant solution under nitrogen(1), Although the use of a syringe pump was called for, there are obvious difficulties associated with purging the solution and assembling such an apparatus under nitrogen, and we report a simple and inexpensive solution. A Male Luer Lock tip (recovered from a broken syringe) was sweated onto the flattened tip of a pressure-equalizing addition funnel and a syringe needle was attached. Judicious selection of needle length, bore size, and reactant volume can be used to control the addition time simply and reproducibly. With a 250-mL funnel, the flow rate changes by <25% from the beginning to the end of the addition. (In fact, a reduction in the rate of addition may even be advantageous as the reaction proceeds, the reagent in the receiving flask is consumed, its concentration drops, and the rate of reaction will decrease). A piece of fine Teflon tubing of appropriate length attached to the needle can be used to reduce the flow rate even further, but this is only necessary for very slow rates of addition. For example, the time of addition of 200 mL, of an ethanolic solution could be varied from approximately 5 minutes (150mm/17 gauge) to approximately 5 h (200mm/22 gauge), and once the addition time for a

  15. Proton-transfer reactions of acridine in water-containing ionic-liquid-rich mixtures.

    Science.gov (United States)

    Kumar, Vinod; Pandey, Ashish; Pandey, Siddharth

    2013-12-02

    To assess the potential of ionic liquids (ILs) as a solubilizing media that facilitates proton-transfer reactions, acridine prototropism is investigated using UV/Vis molecular absorbance as well as steady-state and time-resolved fluorescence with different ILs in the presence of a small amount of dilute acid or base. It is found that protonation and deprotonation of acridine, when dissolved in different ILs, can be triggered by the addition of a small amount of dilute aqueous HCl and NaOH, respectively, in both the ground and excited states, irrespective of the identity of the IL. However, the amount of dilute acid/base needed to protonate/deprotonate acridine dissolved in different ILs is found to vary from one IL to another. Steady-state fluorescence measurements also imply the presence of interactions between the acidic proton(s) of IL cation and excited acridine. The interconversion of neutral and protonated acridine, as well as the presence of a weakly fluorescent complex between excited acridine and the acidic proton(s) of the IL cation, is further corroborated by the parameters recovered from the fitting of the excited-state intensity-decay data. It is established that ILs as solubilizing media readily support facile proton transfer in both ground and excited states.

  16. Model studies on the pattern of volatiles generated in mixtures of amino acids, lipid-oxidation-derived aldehydes, and glucose.

    Science.gov (United States)

    Adams, An; Kitryté, Vaida; Venskutonis, Rimantas; De Kimpe, Norbert

    2011-02-23

    The development of flavor and browning in thermally treated foods results mainly from the Maillard reaction and lipid degradation but also from the interactions between both reaction pathways. To study these interactions, we analyzed the volatile compounds resulting from model reactions of lysine or glycine with aldehydes originating from lipid oxidation [hexanal, (E)-2-hexenal, or (2E,4E)-decadienal] in the presence and absence of glucose. The main reaction products identified in these model mixtures were carbonyl compounds, resulting essentially from amino-acid-catalyzed aldol condensation reactions. Several 2-alkylfurans were detected as well. Only a few azaheterocyclic compounds were identified, in particular 5-butyl-2-propylpyridine from (E)-2-hexenal model systems and 2-pentylpyridine from (2E,4E)-decadienal model reactions. Although few reaction products were found resulting from the condensation of an amino acid with a lipid-derived aldehyde, the amino acid plays an important role in catalyzing the degradation and further reaction of these carbonyl compounds. These results suggest that amino-acid-induced degradations and further reactions of lipid oxidation products may be of considerable importance in thermally processed foods.

  17. Mixtures and mineral reactions

    Energy Technology Data Exchange (ETDEWEB)

    Saxena, S.; Ganguly, J.

    1987-01-01

    Considerable progress has been made in our understanding of the physicochemical evolution of natural rocks through systematic analysis of the compositional properties and phase relations of their mineral assemblages. This book brings together concepts of classical thermodynamics, solution models, and atomic ordering and interactions that constitute a basis of such analysis, with examples of application to subsolidus petrological problems.

  18. Artifact-Free and Detection-Profile-Independent Higher-Order Fluorescence Correlation Spectroscopy for Microsecond-Resolved Kinetics. 2. Mixtures and Reactions.

    Science.gov (United States)

    Abdollah-Nia, Farshad; Gelfand, Martin P; Van Orden, Alan

    2017-03-23

    Fluorescence correlation spectroscopy (FCS) is a primary tool in the time-resolved analysis of nonreacting or reacting molecules in solution, based on fluorescence intensity fluctuations. However, conventional FCS alone is insufficient for a complete determination of reaction or mixture parameters. In an accompanying article, a technique for the computation of artifact-free higher-order correlations with microsecond time resolution was described. Here, we demonstrate the applications of the technique to analyze the systems of fast and slow reactions. As an example of non- or slow-reacting systems, the technique is applied to resolve two-component mixtures of labeled oligonucleotides. Next, the protonation reaction of fluorescein isothiocyanate in phosphate buffer is analyzed as an example of fast reactions (relaxation time system, the simple factorized form of cumulant-based higher-order correlations is exploited to remove the dependence on the molecular detection function (MDF). Therefore, there is no need to model and characterize the experimental MDF, and the precision and the accuracy of the technique are enhanced. It is verified that the higher-order correlation analysis enables a complete and simultaneous determination of the number and brightness parameters of mixing or reacting molecules, the reaction relaxation time, and forward and reverse reaction rates.

  19. Caffeic acid inhibits the formation of 1-hydroxyethyl radical in the reaction mixture of rat liver microsomes with ethanol partly through its metal chelating activity.

    Science.gov (United States)

    Ikeda, Hideyuki; Kimura, Yuka; Masaki, Miho; Iwahashi, Hideo

    2011-05-01

    Effect of caffeic acid on the formation of 1-hydroxyethyl radicals via the microsomal ethanol-oxidizing system pathway was examined. The electron spin resonance spin trapping showed that 1-hydroxyethyl radicals form in the control reaction mixture which contained 0.17 M ethanol, 1 mg protein/ml rat river microsomes, 0.1 M α-(4-pyridyl-1-oxide)-N-tert-butylnitrone, 5 mM nicotinamide adenine dinucleotide phosphate and 30 mM phosphate buffer (pH 7.4). When the electron spin resonance spectra of the control reaction mixtures with caffeic acid were measured, caffeic acid inhibited the formation of 1-hydroxyethyl radicals in a concentration dependent manner. Gallic acid, dopamine, l-dopa, chlorogenic acid and catechin also inhibited the formation of 1-hydroxyethyl radicals. Above results indicated that the catechol moiety is essential to the inhibitory effect. Caffeic acid seems to chelate of iron ion at the catechol moiety. Indeed, the inhibitory effect by caffeic acid was greatly diminished in the presence of desferrioxamine, a potent iron chelator which removes iron ion in the Fe (III)-caffeic acid complex. Since Fe (III)-desferrioxamine complex is active for the 1-hydroxyethyl radicals formation, caffeic acid inhibits the formation of 1-hydroxyethyl radicals in the reaction mixture partly through its metal chelating activity.

  20. The use of dead-end and cross-flow nanofiltration to purify prebiotic oligosaccharides from reaction mixtures

    Directory of Open Access Journals (Sweden)

    Alistair S. Grandison

    2002-11-01

    Full Text Available Nanofiltration (NF of model sugar solutions and commercial oligosaccharide mixtures were studied in both dead-end and cross-flow modes. Preliminary trials, with a dead-end filtration cell, demonstrated the feasibility of fractionating monosaccharides from disaccharides and oligosaccharides in mixtures, using loose nanofiltration (NF-CA-50, NF-TFC-50 membranes. During the nanofiltration purification of a commercial oligosaccharide mixture, yields of 19% (w w-1 for the monosaccharides and 88% (w w-1 for di, and oligosaccharides were obtained for the NF-TFC-50 membrane after four filtration steps, indicating that removal of the monosaccharides is possible, with only minor losses of the oligosaccharide content of the mixture. The effects of pressure, feed concentration, and filtration temperature were studied in similar experiments carried out in a cross-flow system, in full recycle mode of operation. The rejection rates of the sugar components increased with increasing pressure, and decreased with both increasing total sugar concentration in the feed and increasing temperature. Continuous diafiltration (CD purification of model sugar solutions and commercial oligosaccharide mixtures using NF-CA-50 (at 25oC and DS-5-DL (at 60oC membranes, gave yield values of 14 to 18% for the monosaccharide, 59 to 89% for the disaccharide and 81 to 98% for the trisaccharide present in the feed. The study clearly demonstrates the potential of cross flow nanofiltration in the purification of oligosaccharide mixtures from the contaminant monosaccharides.

  1. Use of pruned computational neural networks for processing the response of oscillating chemical reactions with a view to analyzing nonlinear multicomponent mixtures.

    Science.gov (United States)

    Hervás, C; Toledo, R; Silva, M

    2001-01-01

    The suitability of pruned computational neural networks (CNNs) for resolving nonlinear multicomponent systems involving synergistic effects by use of oscillating chemical reaction-based methods implemented using the analyte pulse perturbation technique is demonstrated. The CNN input data used for this purpose are estimates provided by the Levenberg-Marquardt method in the form of a three-parameter Gaussian curve associated with the singular profile obtained when the oscillating system is perturbed by an analyte mixture. The performance of the proposed method was assessed by applying it to the resolution of mixtures of pyrogallol and gallic acid based on their perturbating effect on a classical oscillating chemical system, viz. the Belousov-Zhabotinskyi reaction. A straightforward network topology (3:3:2, with 18 connections after pruning) allowed the resolution of mixtures of the two analytes in concentration ratios from 1:7 to 6:2 with a standard error of prediction for the testing set of 4.01 and 8.98% for pyrogallol and gallic acid, respectively. The reduced dimensions of the selected CNN architecture allowed a mathematical transformation of the input vector into the output one that can be easily implemented via software. Finally, the suitability of response surface analysis as an alternative to CNNs was also tested. The results were poor (relative errors were high), which confirms that properly selected pruned CNNs are effective tools for solving the analytical problem addressed in this work.

  2. Human taste and umami receptor responses to chemosensorica generated by Maillard-type N²-alkyl- and N²-arylthiomethylation of guanosine 5'-monophosphates.

    Science.gov (United States)

    Suess, Barbara; Brockhoff, Anne; Degenhardt, Andreas; Billmayer, Sylvia; Meyerhof, Wolfgang; Hofmann, Thomas

    2014-11-26

    Structural modification of the exocyclic amino function of guanosine 5'-monophosphate (5'-GMP) by Maillard-type reactions with reducing carbohydrates was recently found to increase the umami-enhancing activity of the nucleotide upon S-N(2)-1-carboxyalkylation and S-N(2)-(1-alkylamino)carbonylalkylation, respectively. Since the presence of sulfur atoms in synthetic N(2)-alkylated nucleotides was reported to be beneficial for sensory activity, a versatile Maillard-type modification of 5'-GMP upon reaction with glycine's Strecker aldehyde formaldehyde and organic thiols was performed in the present study. A series of N(2)-(alkylthiomethyl)guanosine and N(2)-(arylthiomethyl)guanosine 5'-monophosphates was generated and the compounds were evaluated to what extent they enhance the umami response to monosodium L-glutamate in vivo by a paired-choice comparison test using trained human volunteers and in vitro by means of cell-based umami taste receptor assay. Associated with a high umami-enhancing activity (β-value 5.1), N(2)-(propylthiomethyl)guanosine 5'-monophosphate could be generated when 5'-GMP reacted with glucose, glycine, and the onion-derived odorant 1-propanethiol, thus opening a valuable avenue to produce high-potency umami-enhancing chemosensorica from food-derived natural products by kitchen-type chemistry.

  3. Determination of acrylamide formed in asparagine/D-glucose maillard model systems by using gas chromatography with headspace solid-phase microextraction.

    Science.gov (United States)

    El-Ghorab, Ahmed H; Fujioka, Kazutoshi; Shibamoto, Takayuki

    2006-01-01

    A gas chromatographic method, along with a headspace solid-phase microextraction (HS-SPME), was developed for the determination of acrylamide formed in Maillard reaction model systems. The developed method was validated by liquid chromatography/mass spectrometry. A headspace sample was collected from an aqueous acrylamide solution (100 microg/mL) by SPME and directly injected into a gas chromatograph equipped with a nitrogen-phosphorus detector. The recovery of acrylamide from an aqueous solution was satisfactory, i.e, >93% under the conditions used. Acrylamide formed in an asparagine/D-glucose (molar ratio, 1/2) Maillard reaction model system heated at 150 and 170 degrees C for 20 min was collected and analyzed by the newly developed method using gas chromatography with nitrogen-phosphorus detection and HS-SPME. The amounts of acrylamide were 318 +/- 33 microg/g asparagine from a sample heated at 150 degrees C and 3329 +/- 176 microg/g asparagine from a sample heated at 170 degrees C. Addition of cysteamine or glutathione to the above model system reduced acrylamide formation. Acrylamide formation was not observed when cysteamine or glutathione was added to asparagine in the above model systems to obtain equimolar concentrations of both compounds. This newly developed method is simple and sensitive, and requires no solvent extraction.

  4. Quantitative NMR spectroscopy of complex technical mixtures using a virtual reference: chemical equilibria and reaction kinetics of formaldehyde-water-1,3,5-trioxane.

    Science.gov (United States)

    Maiwald, Michael; Grützner, Thomas; Ströfer, Eckhard; Hasse, Hans

    2006-07-01

    Quantitative 1H NMR spectroscopy was used to study chemical equilibria and reaction kinetics of both the formation and decomposition of 1,3,5-trioxane in aqueous formaldehyde solutions. The reaction was homogeneously catalyzed with up to 0.10 g g(-1) sulfuric acid at temperatures between 360 and 383 K so that most of the experiments had to be carried out pressurized. The studied mixtures were complex due to the formation of methylene glycol and poly(oxymethylene) glycols in aqueous formaldehyde and the presence of considerable amounts of ionized species. Most common internal standards are decomposed by the hot sulfuric acid and external standards were not applicable using the flow NMR probe or pressurizable NMR sample tubes. Therefore, for the quantification of the small trioxane signals, a novel procedure was applied, in which electronically generated NMR signals were used as highly stable Virtual References (VR). The NMR decoupler channel with wave-form generator was used as the source of the reference signal, which was irradiated into the probe using the lock coil. Details on the experimental procedure are presented. It is shown that the presented method yields reliable quantitative reaction data for the complex studied mixtures.

  5. Rapid synthesis of MoSi2-Si3N4 nanocomposite via reaction milling of Si and Mo powder mixture

    Institute of Scientific and Technical Information of China (English)

    Majid Abdellahi; Alireza Amereh; Hamed Bahmanpou; and Behzad Sharafati

    2013-01-01

    The nanocomposite of MoSi2-Si3N4 (molybdenum disilicide-silicon nitride) was synthesized by reaction milling of the Mo and Si powder mixture. Changing the processing parameters led to the formation of diff erent products such asα-andβ-MoSi2, Si3N4, Mo2N, and Mo5Si3 at various milling times. A thermodynamic appraisal showed that the milling of Mo32Si68 powder mixture was associated with highly exothermic mechanically induced self-sustaining reaction (MSR) between Mo and Si. The MSR took place around 5 h of milling led to the formation ofα-MoSi2 and the reaction between Si and N2 to produce Si3N4 under a nitrogen pressure of 1 MPa. By increasing the nitrogen pressure to 5 MPa, more heat is released, resulting in the dissociation of Si3N4 and the transformation ofα-MoSi2 toβ-MoSi2. Heat treatment was also performed on the milled samples and led to the formation of Mo2N and the transformation ofα-MoSi2 toβ-MoSi2 at the milling times of 10 and 40 h, respectively.

  6. A Kinetic Modeling study on the Oxidation of Primary Reference Fuel?Toluene Mixtures Including Cross Reactions between Aromatics and Aliphatics

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Y; Miyoshi, A; Koshi, M; Pitz, W J

    2008-01-09

    A detailed chemical kinetic model for the mixtures of Primary Reference Fuel (PRF: n-heptane and iso-octane) and toluene has been proposed. This model is divided into three parts; a PRF mechanism [T. Ogura et al., Energy & Fuels 21 (2007) 3233-3239], toluene sub-mechanism and cross reactions between PRF and toluene. Toluene sub-mechanism includes the low temperature kinetics relevant to engine conditions. A chemical kinetic mechanism proposed by Pitz et al. [Proc. the 2nd Joint Meeting of the U.S. Combust. Institute (2001)] was used as a starting model and modified by updating rate coefficients. Theoretical estimations of rate coefficients were performed for toluene and benzyl radical reactions important at low temperatures. Cross-reactions between alkane, alkene, and aromatics were also included in order to account for the acceleration by the addition of toluene into iso-octane recently found in the shock tube study of the ignition delay [Y. Sakai et al, SAE 2007-01-4014 (2007)]. Validations of the model were performed with existing shock tube and flow tube data. The model well predicts the ignition characteristics of toluene and PRF/Toluene mixtures under the wide range of temperatures (500-1700 K) and pressures (2-50 atm). It is found that reactions of benzyl radical with oxygen molecule determine the reactivity of toluene at low temperature. Although the effect of toluene addition to iso-octane is not fully resolved, the reactions of alkene with benzyl radical have the possibility to account for the kinetic interactions between PRF and toluene.

  7. Combustion synthesis by reaction and characterization of nano ferrites: study of fuel aniline, citric and its mixture; Sintese por reacao de combustao e caracterizacao de nanoferritas Ni-Zn: estudo dos combustiveis anilina, acido citrico e sua mistura

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.C. da; Coutinho, J.P.; Costa, A.C.F.M., E-mail: normanda@ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Kiminami, R.H.G.A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Engenharia de Materiais; Freitas, N.L. de [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Tecnologia do Desenvolvimento

    2012-07-01

    The present study aims to evaluate the influence of aniline and citric acid used alone and combined in a ratio of 50% each in the characterization of NiZn ferrite synthesized by combustion reaction method in a muffle furnace. Measurements were made of temperature and reaction time. The nano-powders were characterized by XRD, EDX, textural analysis and SEM. The highest temperature was achieved by the reaction using the mixture of fuel and increased reaction time using citric acid. The nano ferrites using different fuels, and the mixture changed phases, the crystallite size and decreased surface area of the samples with aniline, citric acid and a mixture of both, respectively. The powder morphology ranged from presenting the formation of irregular blocks for the use of citric agglomerated in the form of skeins with aniline and a mixture to agglomerate larger particles. (author)

  8. Chemical reaction rates and non-equilibrium pressure of reacting gas mixtures in the state-to-state approach

    Energy Technology Data Exchange (ETDEWEB)

    Kustova, Elena V., E-mail: e.kustova@spbu.ru [Department of Mathematics and Mechanics, Saint Petersburg State University, 198504 Universitetskiy pr. 28, Saint Petersburg (Russian Federation); Kremer, Gilberto M., E-mail: kremer@fisica.ufpr.br [Departamento de Física, Universidade Federal do Paraná, Caixa Postal 19044, 81531-980 Curitiba (Brazil)

    2014-12-05

    Highlights: • State-to-state approach for coupled vibrational relaxation and chemical reactions. • Self-consistent model for rates of non-equilibrium reactions and energy transitions. • In viscous flows mass action law is violated. • Cross coupling between reaction rates and non-equilibrium pressure in viscous flow. • Results allow implementing the state-to-state approach for viscous flow simulations. - Abstract: Viscous gas flows with vibrational relaxation and chemical reactions in the state-to-state approach are analyzed. A modified Chapman–Enskog method is used for the determination of chemical reaction and vibrational transition rates and non-equilibrium pressure. Constitutive equations depend on the thermodynamic forces: velocity divergence and chemical reaction/transition affinity. As an application, N{sub 2} flow with vibrational relaxation across a shock wave is investigated. Two distinct processes occur behind the shock: for small values of the distance the affinity is large and vibrational relaxation is in its initial stage; for large distances the affinity is small and the chemical reaction is in its final stage. The affinity contributes more to the transition rate than the velocity divergence and the effect of these two contributions are more important for small distances from the shock front. For the non-equilibrium pressure, the term associated with the bulk viscosity increases by a small amount the hydrostatic pressure.

  9. Co-formation of hydroperoxides and ultra-fine particles during the reactions of ozone with a complex VOC mixture under simulated indoor conditions

    DEFF Research Database (Denmark)

    Fan, Z.H.; Weschler, Charles J.; Han, IK

    2005-01-01

    in the O-3/23 VOCs system. The present study confirmed the findings of a previous study carried out in a real-world office and generated new findings regarding co-formation of UFP. Through a comparative analysis of H2O2* yields under different reaction conditions, this study demonstrates that VOCs co......) under simulated indoor conditions. The VOC mixture contained 23 compounds, including two terpenes (d-limonene and alpha-pinene), two unsaturated alkenes (1-decene and 1-octene), and 19 other saturated organic compounds. These compounds are commonly found in indoor air but their concentrations were...

  10. Chemical reaction rates and non-equilibrium pressure of reacting gas mixtures in the state-to-state approach

    Science.gov (United States)

    Kustova, Elena V.; Kremer, Gilberto M.

    2014-12-01

    Viscous gas flows with vibrational relaxation and chemical reactions in the state-to-state approach are analyzed. A modified Chapman-Enskog method is used for the determination of chemical reaction and vibrational transition rates and non-equilibrium pressure. Constitutive equations depend on the thermodynamic forces: velocity divergence and chemical reaction/transition affinity. As an application, N2 flow with vibrational relaxation across a shock wave is investigated. Two distinct processes occur behind the shock: for small values of the distance the affinity is large and vibrational relaxation is in its initial stage; for large distances the affinity is small and the chemical reaction is in its final stage. The affinity contributes more to the transition rate than the velocity divergence and the effect of these two contributions are more important for small distances from the shock front. For the non-equilibrium pressure, the term associated with the bulk viscosity increases by a small amount the hydrostatic pressure.

  11. Shock-induced chemical reactions in titanium-silicon powder mixtures of different morphologies: Time-resolved pressure measurements and materials analysis

    Science.gov (United States)

    Thadhani, N. N.; Graham, R. A.; Royal, T.; Dunbar, E.; Anderson, M. U.; Holman, G. T.

    1997-08-01

    The response of porous titanium (Ti) and silicon (Si) powder mixtures with small, medium, and coarse particle morphologies is studied under high-pressure shock loading, employing postshock materials analysis as well as nanosecond, time-resolved pressure measurements. The objective of the work was to provide an experimental basis for development of models describing shock-induced solid-state chemistry. The time-resolved measurements of stress pulses obtained with piezoelectric polymer (poly-vinyl-di-flouride) pressure gauges provided extraordinary sensitivity for determination of rate-dependent shock processes. Both techniques showed clear evidence for shock-induced chemical reactions in medium-morphology powders, while fine and coarse powders showed no evidence for reaction. It was observed that the medium-morphology mixtures experience simultaneous plastic deformation of both Ti and Si particles. Fine morphology powders show particle agglomeration, while coarse Si powders undergo extensive fracture and entrapment within the plastically deformed Ti; such processes decrease the propensity for initiation of shock-induced reactions. The change of deformation mode between fracture and plastic deformation in Si powders of different morphologies is a particularly critical observation. Such a behavior reveals the overriding influence of the shock-induced, viscoplastic deformation and fracture response, which controls the mechanochemical nature of shock-induced solid-state chemistry. The present work in conjunction with our prior studies, demonstrates that the initiation of chemical reactions in shock compression of powders is controlled by solid-state mechanochemical processes, and cannot be qualitatively or quantitatively described by thermochemical models.

  12. Reactions of plutonium dioxide with water and oxygen-hydrogen mixtures: Mechanisms for corrosion of uranium and plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Haschke, John M.; Allen, Thomas H.; Morales, Luis A.

    1999-06-18

    Investigation of the interactions of plutonium dioxide with water vapor and with an oxygen-hydrogen mixture show that the oxide is both chemically reactive and catalytically active. Correspondence of the chemical behavior with that for oxidation of uranium in moist air suggests that similar catalytic processes participate in the mechanism of moisture-enhanced corrosion of uranium and plutonium. Evaluation of chemical and kinetic data for corrosion of the metals leads to a comprehensive mechanism for corrosion in dry air, water vapor, and moist air. Results are applied in confirming that the corrosion rate of Pu in water vapor decreases sharply between 100 and 200 degrees C.

  13. Generation of Maillard compounds from inulin during the thermal processing of Agave tequilana Weber Var. azul.

    Science.gov (United States)

    Mancilla-Margalli, Norma A; López, Mercedes G

    2002-02-13

    During the cooking process of Agave tequilana Weber var. azul to produce tequila, besides the hydrolysis of inulin to generate fermentable sugars, many volatiles, mainly Maillard compounds, are produced, most of which may have a significant impact on the overall flavor of tequila. Exudates (agave juice) from a tequila company were collected periodically, and color, Brix, fructose concentration, and reducing sugars were determined as inulin breakdown took place. Maillard compounds were obtained by extraction with CH(2)Cl(2), and the extracts were analyzed by GC-MS. Increments in color, Brix, and reducing sugars were observed as a function of time, but a decrease in fructose concentration was found. Many Maillard compounds were identified in the exudates, including furans, pyrans, aldehydes, and nitrogen and sulfur compounds. The most abundant Maillard compounds were methyl-2-furoate, 2,3-dihydroxy-3,5-dihydro-6-methyl-4(H)-pyran-4-one, and 5-(hydroxymethyl)furfural. In addition, a series of short- and long-chain fatty acids was also found. A large number of the volatiles in A. tequilana Weber var. azul were also detected in tequila extracts, and most of these have been reported as a powerful odorants, responsible for the unique tequila flavor.

  14. Steady-state studies of the reactions of H2O-CO and CO2-H2 mixtures with liquid iron

    Science.gov (United States)

    Sasaki, Y.; Belton, G. R.

    1998-08-01

    Studies have been made of the steady-stata composition of liquid iron exposed to high flow rates of H2O-CO mixtures at 1550 °C to 1700 °C and CO2-H2 mixtures at 1600 °C. Values of the steady-state activity of oxygen have been established by measurement of either the carbon concentration or the silicon concentration when the iron was held in a silica crucible. Additions of sulfur or selenium to the iron have been found to result in steady-state oxygen activities, which differ significantly from those expected from water-gas equilibrium. The results are interpreted to show that the ratio of the apparent first-order rate constants for the reactions of H2O and CO2 with liquid iron is about 3 at 1600 °C. It is shown that the dependencies of the rate constants on the activities of sulfur, oxygen, and selenium must, even if complex, be similar for the H2O and CO2 reactions with liquid iron, to a good approximation.

  15. Effect of some naturally occurring iron ion chelators on the formation of radicals in the reaction mixtures of rat liver microsomes with ADP, Fe3+ and NADPH

    Science.gov (United States)

    Minakata, Katsuyuki; Fukushima, Kazuaki; Nakamura, Masayuki; Iwahashi, Hideo

    2011-01-01

    In order to clarify the mechanism by polyphenols of protective effects against oxidative damage or by quinolinic acid of its neurotoxic and inflammatory actions, effects of polyphenols or quinolinic acid on the radical formation were examined. The ESR measurements showed that some polyphenols such as caffeic acid, catechol, gallic acid, D-(+)-catechin, L-dopa, chlorogenic acid and L-noradrenaline inhibited the formation of radicals in the reaction mixture of rat liver microsomes with ADP, Fe3+ and NADPH. The ESR measurements showed that α-picolinic acid, 2,6-pyridinedicarboxylic acid and quinolinic acid (2,3-pyridinedicarboxylic acid) enhanced the formation of radicals in the reaction mixture of rat liver microsomes with Fe3+ and NADPH. Caffeic acid and α-picolinic acid had no effects on the formation of radicals in the presence of EDTA, suggesting that the chelation of iron ion seems to be related to the inhibitory and enhanced effects. The polyphenols may exert protective effects against oxidative damage of erythrocyte membrane, ethanol-induced fatty livers, cardiovascular diseases, inflammatory and cancer through the mechanism. On the other hand, quinolinic acid may exert its neurotoxic and inflammatory effects because of the enhanced effect on the radical formation. PMID:22128221

  16. Effect of some naturally occurring iron ion chelators on the formation of radicals in the reaction mixtures of rat liver microsomes with ADP, Fe and NADPH.

    Science.gov (United States)

    Minakata, Katsuyuki; Fukushima, Kazuaki; Nakamura, Masayuki; Iwahashi, Hideo

    2011-11-01

    In order to clarify the mechanism by polyphenols of protective effects against oxidative damage or by quinolinic acid of its neurotoxic and inflammatory actions, effects of polyphenols or quinolinic acid on the radical formation were examined. The ESR measurements showed that some polyphenols such as caffeic acid, catechol, gallic acid, D-(+)-catechin, L-dopa, chlorogenic acid and L-noradrenaline inhibited the formation of radicals in the reaction mixture of rat liver microsomes with ADP, Fe(3+) and NADPH. The ESR measurements showed that α-picolinic acid, 2,6-pyridinedicarboxylic acid and quinolinic acid (2,3-pyridinedicarboxylic acid) enhanced the formation of radicals in the reaction mixture of rat liver microsomes with Fe(3+) and NADPH. Caffeic acid and α-picolinic acid had no effects on the formation of radicals in the presence of EDTA, suggesting that the chelation of iron ion seems to be related to the inhibitory and enhanced effects. The polyphenols may exert protective effects against oxidative damage of erythrocyte membrane, ethanol-induced fatty livers, cardiovascular diseases, inflammatory and cancer through the mechanism. On the other hand, quinolinic acid may exert its neurotoxic and inflammatory effects because of the enhanced effect on the radical formation.

  17. Reactions in a Mixture of CH4 and CO2 under the Aciton of Microwave Discharge at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    YunpengXu; ZhijianTian; 等

    2002-01-01

    Reactions between CH4 and CO2 under the action of continuous microwave discharge at atmospheric pressure were studied in a special homemade reactor,The main products were CO and H2,while acetylene and ethylene were also found in the products.Experimental results show that conversions of CH4 and CO2 could be higher than 90% without the presence of any catalyst,Effects of CO2/CH4 molar ratio and total flow rate of the feed gas on the reaction were also investigated.

  18. Mechano-chemical reactions in LiBH{sub 4} + VCl{sub n} (n = 2 and 3) mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Llamas-Jansa, Isabel, E-mail: isabel.llamas@ife.no [Institute for Energy Technology, Physics Department, P.O. Box 40, NO-2027, Kjeller (Norway); Aliouane, Nadir; Deledda, Stefano; Fonnelop, Jon Erling; Frommen, Christoph; Lieutenant, Klaus; Sartori, Sabrina; Sorby, Magnus H.; Hauback, Bjorn C. [Institute for Energy Technology, Physics Department, P.O. Box 40, NO-2027, Kjeller (Norway)

    2011-09-15

    Research highlights: > Mechano-chemically activated metathesis reactions between LiBH{sub 4} and VCln (n = 2 and 3). > Only crystalline LiCl and unreacted LiBH{sub 4} are observed by X-ray diffraction. > VCl{sub 3} reactions have stronger thermodynamical driving forces. - Abstract: Mechano-chemical routes to the metathesis reaction 4LiBH{sub 4} + VCl{sub n} {yields} Li{sub 4-n}V(BH{sub 4}){sub 4} + nLiCl (n = 2 and 3) are explored at room and liquid nitrogen temperatures. The produced samples consist of crystalline LiCl and unreacted LiBH{sub 4}. No other crystalline phases are observed directly by powder X-ray diffraction. The highest reactivity was observed when using VCl{sub 3}. Two possible reaction paths are proposed in order to explain this result: (a) 2LiBH{sub 4} + VCl{sub 2} {yields} 2LiCl + VB{sub 2} + 4H{sub 2}, with {Delta}H = -188 kJ/mol and (b) 3LiBH{sub 4} + VCl{sub 3} {yields} 3LiCl + 1/2B{sub 2}H{sub 6} + VB{sub 2} + 9/2H{sub 2}, with {Delta}H = -258 kJ/mol. The calculated enthalpy values show that reactions with VCl{sub 3} have stronger thermodynamical driving forces than with VCl{sub 2}, corroborating the experimental results. Still, the different experimental methods lead to the same final products, with longer milling times being necessary to remove the precursor traces in the case of VCl{sub 2} and cryomilling. The results shed some light on the efficiency of mechano-chemical methods for the synthesis of mixed metal borohydrides based on LiBH{sub 4} and V-chlorides.

  19. New prediction model for probe specificity in an allele-specific extension reaction for haplotype-specific extraction (HSE) of Y chromosome mixtures.

    Science.gov (United States)

    Rothe, Jessica; Watkins, Norman E; Nagy, Marion

    2012-01-01

    Allele-specific extension reactions (ASERs) use 3' terminus-specific primers for the selective extension of completely annealed matches by polymerase. The ability of the polymerase to extend non-specific 3' terminal mismatches leads to a failure of the reaction, a process that is only partly understood and predictable, and often requires time-consuming assay design. In our studies we investigated haplotype-specific extraction (HSE) for the separation of male DNA mixtures. HSE is an ASER and provides the ability to distinguish between diploid chromosomes from one or more individuals. Here, we show that the success of HSE and allele-specific extension depend strongly on the concentration difference between complete match and 3' terminal mismatch. Using the oligonucleotide-modeling platform Visual Omp, we demonstrated the dependency of the discrimination power of the polymerase on match- and mismatch-target hybridization between different probe lengths. Therefore, the probe specificity in HSE could be predicted by performing a relative comparison of different probe designs with their simulated differences between the duplex concentration of target-probe match and mismatches. We tested this new model for probe design in more than 300 HSE reactions with 137 different probes and obtained an accordance of 88%.

  20. Model studies on the pattern of volatiles generated in mixtures of amino acids, lipid oxidation-derived aldehydes, and glucose

    OpenAIRE

    Adams, An; Kitrytė, Vaida; Venskutonis, Rimantas; De Kimpe, Norbert

    2011-01-01

    The development of flavor and browning in thermally treated foods results mainly from the Maillard reaction and lipid degradation but also from the interactions between both reaction pathways. To study these interactions, we analyzed the volatile compounds resulting from model reactions of lysine or glycine with aldehydes originating from lipid oxidation [hexanal, (E)-2-hexenal, or (2E,4E)-decadienal] in the presence and absence of glucose. The main reaction products identified in these model...

  1. A simple fast microwave-assisted synthesis of thermoelectric bismuth telluride nanoparticles from homogeneous reaction-mixture

    Science.gov (United States)

    Pradhan, Susmita; Das, Rashmita; Bhar, Radhaballabh; Bandyopadhyay, Rajib; Pramanik, Panchanan

    2017-02-01

    A new simple chemical method for synthesis of nanocrystalline bismuth telluride (Bi2Te3) has been developed by microwave assisted reduction of homogeneous tartrate complexes of bismuth and tellurium metal ions with hydrazine. The reaction is performed at pH 10. The nano-crystallites have rhombohedral phase identified by XRD. The size distribution of nanoparticle is narrow and it ranges between 50 to 70 nm. FESEM shows that the fine powders are composed of small crystallites. The TEM micrographs show mostly deformed spherical particles and the lattice fringes are found to be 0.137 nm. Energy dispersive X-ray spectroscopy (EDX) analysis shows the atomic composition ratio between bismuth and tellurium is 2:3. Thermoelectric properties of the materials are studied after sintering by spark plasma sintering method (SPS). The grain size of the material after sintering is in the nanometer range. The material shows enhanced Seebeck coefficient and electrical conductivity value at 300 K. The figure of merit is found to be 1.18 at 300 K.

  2. From dihydrated iron(III) phosphate to monohydrated ammonium-iron(II) phosphate: Solvothermal reaction mediated by acetone-urea mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Alfonso, Belen F., E-mail: mbafernandez@uniovi.es [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n 33007 Oviedo (Spain); Trobajo, Camino [Departamento de Quimica Organica e Inorganica, Universidad de Oviedo-CINN, Julian Claveria 8, 33006 Oviedo (Spain); Pique, Carmen [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n 33007 Oviedo (Spain); Garcia, Jose R. [Departamento de Quimica Organica e Inorganica, Universidad de Oviedo-CINN, Julian Claveria 8, 33006 Oviedo (Spain); Blanco, Jesus A. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n 33007 Oviedo (Spain)

    2012-12-15

    By reaction between synthetic phosphosiderite FePO{sub 4}{center_dot}2H{sub 2}O, urea (NH{sub 2}){sub 2}CO, and acetone (CH{sub 3}){sub 2}CO, we report a novel solvothermal synthesis of polycrystalline NH{sub 4}FePO{sub 4}{center_dot}H{sub 2}O. The preparation of other two individual phases, NH{sub 4}Fe{sub 2}(OH)(PO{sub 4}){sub 2}{center_dot}2H{sub 2}O and NH{sub 4}Fe{sub 2}(PO{sub 4}){sub 2}, is also described. The obtained product is a function of the reaction time and the N/P molar ratio in the reagent mixture, and the existence of structural memory in the dissolution-precipitation processes is discussed. Below 25 K, NH{sub 4}FePO{sub 4}{center_dot}H{sub 2}O behaves magnetically in a complex way, because both ferromagnetic and antiferromagnetic signals are superimposed, suggesting the existence of a canting of iron(II) magnetic moments. - Graphical abstract: Solvothermal synthesis of polycrystalline NH{sub 4}FePO{sub 4}{center_dot}H{sub 2}O is presented. The preparation of other two individual phases, NH{sub 4}Fe{sub 2}(OH)(PO{sub 4}){sub 2}{center_dot}2H{sub 2}O and NH{sub 4}Fe{sub 2}(PO{sub 4}){sub 2} as a function of the N/P molar ratio in the reagent mixture and the reaction time, is also described. Highlights: Black-Right-Pointing-Pointer Solvothermal synthesis of NH{sub 4}FePO{sub 4}{center_dot}H{sub 2}O from an Fe(III) phosphate: reduction process. Black-Right-Pointing-Pointer Formation of two intermediate metastable phases: phase diagram. Black-Right-Pointing-Pointer Thermal decomposition in two steps: mass loss of both water and ammonia. Black-Right-Pointing-Pointer Magnetic behaviour: AF+constant spontaneous magnetization.

  3. The transformation sequence of cement-asbestos slates up to 1200 deg. C and safe recycling of the reaction product in stoneware tile mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Gualtieri, A.F. [Dipartimento di Scienze della Terra, Universita di Modena e R.E., Via S. Eufemia 19, I-41100 Modena (Italy)], E-mail: alex@unimore.it; Cavenati, C.; Zanatto, I.; Meloni, M. [ZETADI S.r.l., Via dell' Artigianato 10, I-21010 Ferno (Italy); Elmi, G. [GE.PR.IN. S.r.l., Via Vaccari 48, I-41100 Modena (Italy); Gualtieri, M. Lassinantti [Dipartimento di Fisica, Universita di Modena e R.E., Via Campi 213/a, I-41100 Modena (Italy)

    2008-04-01

    Cement-asbestos is the main asbestos containing material still found in most of the European countries such as Italy. Man- and weathering-induced degradation of the cement-asbestos slates makes them a source of dispersion of asbestos fibres and represents a priority cause of concern. This concern is the main prompt for the actual policy of abatement and disposal of asbestos containing materials in controlled wastes. An alternative solution to the disposal in dumping sites is the direct temperature-induced transformation of the cement-asbestos slates into non-hazardous mineral phases. This patented process avoids the stage of mechanical milling of the material before the treatment, which improves the reactivity of the materials but may be critical for the dispersion of asbestos fibres in working and life environment. For the first time, this paper reports the description of the reaction path taking place during the firing of cement-asbestos slates up to the complete transformation temperature, 1200 deg. C. The reaction sequence was investigated using different experimental techniques such as optical and electron microscopy, in situ and ex situ quali-quantitative X-ray powder diffraction. The understanding of the complex reaction path is of basic importance for the optimization of industrial heating processes leading to a safe recycling of the transformed product. For the recycling of asbestos containing materials, the Italian laws require that the product of the crystal chemical transformation of asbestos containing materials must be entirely asbestos-free, and should not contain more than 0.1 wt% fraction of the carcinogenic substances such as cristobalite. Moreover, if fibrous phases other than asbestos (with length to diameter ratio >3) are found, they must have a geometrical diameter larger than 3 {mu}m. We have demonstrated that using an interplay of different experimental techniques, it is possible to safely verify the complete transformation of asbestos

  4. The transformation sequence of cement-asbestos slates up to 1200 degrees C and safe recycling of the reaction product in stoneware tile mixtures.

    Science.gov (United States)

    Gualtieri, A F; Cavenati, C; Zanatto, I; Meloni, M; Elmi, G; Gualtieri, M Lassinantti

    2008-04-01

    Cement-asbestos is the main asbestos containing material still found in most of the European countries such as Italy. Man- and weathering-induced degradation of the cement-asbestos slates makes them a source of dispersion of asbestos fibres and represents a priority cause of concern. This concern is the main prompt for the actual policy of abatement and disposal of asbestos containing materials in controlled wastes. An alternative solution to the disposal in dumping sites is the direct temperature-induced transformation of the cement-asbestos slates into non-hazardous mineral phases. This patented process avoids the stage of mechanical milling of the material before the treatment, which improves the reactivity of the materials but may be critical for the dispersion of asbestos fibres in working and life environment. For the first time, this paper reports the description of the reaction path taking place during the firing of cement-asbestos slates up to the complete transformation temperature, 1200 degrees C. The reaction sequence was investigated using different experimental techniques such as optical and electron microscopy, in situ and ex situ quali-quantitative X-ray powder diffraction. The understanding of the complex reaction path is of basic importance for the optimization of industrial heating processes leading to a safe recycling of the transformed product. For the recycling of asbestos containing materials, the Italian laws require that the product of the crystal chemical transformation of asbestos containing materials must be entirely asbestos-free, and should not contain more than 0.1 wt% fraction of the carcinogenic substances such as cristobalite. Moreover, if fibrous phases other than asbestos (with length to diameter ratio >3) are found, they must have a geometrical diameter larger than 3 microm. We have demonstrated that using an interplay of different experimental techniques, it is possible to safely verify the complete transformation of asbestos

  5. Application of Polymerase Chain Reaction for High Sensitivity Detection of Roundup Ready™ Soybean Seeds and Grains in Varietal Mixtures

    Directory of Open Access Journals (Sweden)

    Ashok Pandey

    2011-01-01

    Full Text Available Strong increase in the production of genetically modified organisms (GMOs observed over the years has led to a consolidation of transgenic seed industries worldwide. The dichotomy between the evaluated risk and the perceived risk of transgenic use has defined their level of acceptability among different global societies. GMOs have been widely applied to agricultural commodities, among them the Roundup Ready™ (RR™ soybean line GTS 40-3-2 has become the most prevalent transgenic crop in the world. This variety was developed to confer plant tolerance against glyphosate-based agricultural herbicide Roundup Ready™. Issues related to detection and traceability of GMOs have gained worldwide interest due to their increasing global diffusion and the related socioeconomic and health implications. Also, due to the widespread use of GMOs in food production, labelling regulations have been established in some countries to protect the right of consumers and producers. Besides regulatory demand, consumer concern issues have resulted in the development of several methods of detecting and quantifying foods derived from genetically engineered crops and their raw materials. Polymerase chain reaction (PCR has been proven to be the method of choice to detect the presence or absence of the introduced genes of GMOs at DNA level. The present paper aims to verify whether the PCR technique can detect RR™ soybean seeds among conventional ones to further certification as non-GM soybean seeds and grains. This analysis could be accomplished through the development of new methodology called 'intentional contamination' of soybean conventional seeds or grains with the respective RR™ soybeans. The results show that the PCR method can be applied with high sensitivity in order to certify conventional soybean seeds and grains.

  6. Rate-determining electron-transfer reactions in highly aqueous alcohol-water mixtures. A quantitative analysis of solvent effects on the oxidation of 4-methoxyphenylacetate by potassium 12-tungstocobaltate(III)

    NARCIS (Netherlands)

    Bietti, M.; Baciocchi, E.; Engberts, J.B.F.N.

    1996-01-01

    Kinetic solvent effects on the rate-determining outer-sphere electron-transfer reaction between 4-methoxy-phenylacetate and potassium 12-tungstocobaltate(III) in highly aqueous alcohol-water mixtures are quantitatively analysed in terms of pairwise Gibbs energy parameters for interaction of the init

  7. Investigation of heat induced reactions between lipid oxidation products and amino acids in lipid rich model systems and hazelnuts.

    Science.gov (United States)

    Karademir, Yeşim; Göncüoğlu, Neslihan; Gökmen, Vural

    2013-07-01

    This study aimed to investigate the contribution of lipid oxidation to non-enzymatic browning reactions in lipid rich model and actual food systems. Hazelnut oil and model reaction mixtures consisting of different amino acids were heated under certain conditions to determine possible lipid oxidation and non-enzymatic browning reaction products. In model systems, the Schiff base of 2,4-decadienal, its decarboxylated form, and reaction products formed after hydrolytic cleavage of the Schiff base or decarboxylated form were identified by high resolution mass spectrometry. No furosine was detected in hazelnuts after roasting at 160 °C while the concentration of free amino acids significantly decreased. 2,4-Decadienal reacted effectively with all amino acids studied through a Maillard type carbonyl-amine condensation pathway. (2E,4E)-Deca-2,4-dien-1-amine was identified as a typical reaction product in model systems and roasted hazelnuts. In lipid-rich foods like hazelnuts, lipid-derived carbonyls might be responsible for potential modifications of free and protein bound amino acids during heating.

  8. Mixture Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Piepel, Gregory F.

    2007-12-01

    A mixture experiment involves combining two or more components in various proportions or amounts and then measuring one or more responses for the resulting end products. Other factors that affect the response(s), such as process variables and/or the total amount of the mixture, may also be studied in the experiment. A mixture experiment design specifies the combinations of mixture components and other experimental factors (if any) to be studied and the response variable(s) to be measured. Mixture experiment data analyses are then used to achieve the desired goals, which may include (i) understanding the effects of components and other factors on the response(s), (ii) identifying components and other factors with significant and nonsignificant effects on the response(s), (iii) developing models for predicting the response(s) as functions of the mixture components and any other factors, and (iv) developing end-products with desired values and uncertainties of the response(s). Given a mixture experiment problem, a practitioner must consider the possible approaches for designing the experiment and analyzing the data, and then select the approach best suited to the problem. Eight possible approaches include 1) component proportions, 2) mathematically independent variables, 3) slack variable, 4) mixture amount, 5) component amounts, 6) mixture process variable, 7) mixture of mixtures, and 8) multi-factor mixture. The article provides an overview of the mixture experiment designs, models, and data analyses for these approaches.

  9. Photooxidation of farnesene mixtures in the presence of NOx: Analysis of reaction products and their implication to ambient PM2.5

    Science.gov (United States)

    Jaoui, M.; Lewandowski, M.; Docherty, K. S.; Corse, E. W.; Lonneman, W. A.; Offenberg, J. H.; Kleindienst, T. E.

    2016-04-01

    Chemical analysis of SOA produced from the irradiation of a mixture of α/β-farnesene/NOx was conducted in a 14.5 m3 smog chamber. SOA collected on glass-fiber filters was solvent extracted, derivatized using BSTFA, and analyzed by GC-MS. Gas-phase products were analyzed using a combination of GC-FID and GC-MS. This analysis showed the occurrence of more than 30 SOA oxygenated species and more than 20 in the gas phase. The major SOA components measured include conjugated α-farnesene trienols, C3-C7 linear dicarboxylic acids, carbonyl compounds, and hydroxy/carbonyl/carboxylic compounds. In the gas phase, the main species identified were formaldehyde, glyoxal, methylglyoxal, acetone, 2,3-dimethyl-oxirane, 2(3H)-furanone, 2-butenedioic acid, 4-oxopentanal, 4-methylenehex-5-enal, and 6-methylhept-5-en-2-one. Proposed reaction schemes are provided for selected compounds. H-atom abstraction and OH addition in α-farnesene oxidation seem to play an important role via the formation of unsaturated radicals containing different numbers of delocalized electrons. Allylic hydrogen abstraction and hydroperoxyalkyl radical channels might play a key role in the oxidation of α-farnesene. The contribution of farnesene SOA products to ambient PM2.5 was investigated by analyzing PM2.5 samples collected during SOAS 2013 field study at a site in Research Triangle Park (RTP), NC. The importance of these findings was supported by the occurrence of several organic species in both field and laboratory samples, suggesting the impact of farnesene on the ambient aerosol burden, mainly in areas where farnesene emissions are high. Although, pentanedioic acid and methylsuccinic acid appear to be candidate markers for farnesene SOA, additional chamber and mechanistic studies are required to estimate the contributions of farnesene to ambient SOA.

  10. Evaluation of the Availability and Antioxidant Capacity of Maillard Compounds Present in Bread Crust: Studies in Caco-2 Cells

    Science.gov (United States)

    de la Cueva, Silvia Pastoriza; Seiquer, Isabel; Mesías, Marta; Rufián-Henares, José Ángel; Delgado-Andrade, Cristina

    2017-01-01

    Bread crust is one of the major contributors to the intake of Maillard reaction products (MRP). MRP improve the organoleptic properties of foods and can provide biological actions such as antioxidant properties. The transport and availability of Amadori compounds (measured as furosine) and hydroxymethylfurfural (HMF)—early and intermediary MRP—from enzymatically digested bread crust (BC) and from its soluble low-molecular weight (LMW) and high-molecular weight (HMW) fractions were investigated in the Caco-2 cell line. The absorption of the early and final MRP pool was tested by measuring the absorbance recovery (280 and 420 nm). The ability of soluble BC or its fractions to lessen the production of reactive oxygen species (ROS) was examined. Amadori compounds (furosine) were transported across Caco-2 cell monolayers from the soluble BC in percentages ranging between 40% and 56%; the lower amount of the compound supplied, the higher transport rate. However, HMF transport rate (35%) was unaffected by the initial amount of the compound. Amadori compounds and HMF contained in the LMW fraction were more efficiently transported than those present in the HMW fraction, suggesting improved absorption when supplied as free forms or linked to LMW compounds. Absorbance recovery at 280 nm was higher from the LMW fraction, whereas higher recovery was detected for the HMW fraction at 420 nm. The digested BC—but not its isolated fractions—was able to significantly reduce ROS production at basal conditions and after subjecting cells to an oxidant. A clear positive action of BC on the antioxidant defence is manifested, seemingly attributable to the combined presence of soluble LMW and HMW products. PMID:28231083

  11. Evaluation of the Availability and Antioxidant Capacity of Maillard Compounds Present in Bread Crust: Studies in Caco-2 Cells

    Directory of Open Access Journals (Sweden)

    Silvia Pastoriza de la Cueva

    2017-01-01

    Full Text Available Bread crust is one of the major contributors to the intake of Maillard reaction products (MRP. MRP improve the organoleptic properties of foods and can provide biological actions such as antioxidant properties. The transport and availability of Amadori compounds (measured as furosine and hydroxymethylfurfural (HMF—early and intermediary MRP—from enzymatically digested bread crust (BC and from its soluble low-molecular weight (LMW and high-molecular weight (HMW fractions were investigated in the Caco-2 cell line. The absorption of the early and final MRP pool was tested by measuring the absorbance recovery (280 and 420 nm. The ability of soluble BC or its fractions to lessen the production of reactive oxygen species (ROS was examined. Amadori compounds (furosine were transported across Caco-2 cell monolayers from the soluble BC in percentages ranging between 40% and 56%; the lower amount of the compound supplied, the higher transport rate. However, HMF transport rate (35% was unaffected by the initial amount of the compound. Amadori compounds and HMF contained in the LMW fraction were more efficiently transported than those present in the HMW fraction, suggesting improved absorption when supplied as free forms or linked to LMW compounds. Absorbance recovery at 280 nm was higher from the LMW fraction, whereas higher recovery was detected for the HMW fraction at 420 nm. The digested BC—but not its isolated fractions—was able to significantly reduce ROS production at basal conditions and after subjecting cells to an oxidant. A clear positive action of BC on the antioxidant defence is manifested, seemingly attributable to the combined presence of soluble LMW and HMW products.

  12. AGE-breakers cleave model compounds, but do not break Maillard crosslinks in skin and tail collagen from diabetic rats.

    Science.gov (United States)

    Yang, Shengzu; Litchfield, John E; Baynes, John W

    2003-04-01

    Advanced glycation end products (AGE), formed by nonenzymatic Maillard reactions between carbohydrate and protein, contribute to the increase in chemical modification and crosslinking of tissue proteins with age. Acceleration of AGE formation in collagen during hyperglycemia, with resultant effects on vascular elasticity and basement membrane permeability, is implicated in the pathogenesis of diabetic complications. AGE-breakers, such as N-phenacylthiazolium (PTB) and N-phenacyl-4,5-dimethylthiazolium (PMT) halides, have been proposed as therapeutic agents for reversing the increase in protein crosslinking in aging and diabetes. We have confirmed that these compounds, as well as the AGE-inhibitor pyridoxamine (PM), cleave the model AGE crosslink, phenylpropanedione, and have studied the effects of these compounds in reversing the increased crosslinking of skin and tail collagen isolated from diabetic rats. Crosslinking of skin collagen, measured as the half-time for solubilization of collagen by pepsin in 0.5M acetic acid, was increased approximately 5-fold in diabetic, compared to nondiabetic rats. Crosslinking of tail tendon collagen, measured as insolubility in 0.05 N acetic acid, was increased approximately 10-fold. Collagen preparations were incubated in the presence or absence of AGE-breakers or PM in phosphate buffer, pH 7.4, for 24h at 37 degrees C. These treatments did not decrease the half-time for solubilization of diabetic skin collagen by pepsin or increase the acid solubility of diabetic tail tendon collagen. We conclude that, although AGE-breakers and PM cleave model crosslinks, they do not significantly cleave AGE crosslinks formed in vivo in skin collagen of diabetic rats.

  13. Nitrogen Forms of Maillard Polymers Dervied from Xy—lose and 15N—Labelled Glycine

    Institute of Scientific and Technical Information of China (English)

    CHENGLILI; WENQIXIAO; 等

    1997-01-01

    Water-soluble,nondialyzable Maillard polymers were prepared by reacting D-xylose with 15N-glycine (and /or glycine)at 68℃ and pH 8.0 at equimolar concentrations of 1,0.5 and 0.1 mol L-1,respectively, for 13 days and partitioned into acid-insoluble(MHA) and acid-soluble(MFA) fractions.The nitrogen froms in these polymers were studied by using the 15N cross polartisation-magic angle spinning nuclear magnetic resonance(CPMAS NMR) technique in combination with chemical methods .The 15N nuclear magnetic resonance(NMR) data showed that while the yield,especially the MHA /MFA ratio,varied considerably with the concentrations of the reactants,the nitrogen distribution patterns of these polymers were quite similar. From 65% to 70% of nitrogen in them was in the secondary amide and /or indole form with 24%-25% present as aliphatic and /or aromatic amines and 5% to 11% as pyrrole and /or pyrrole-like nitrogen,More than half (50%-77%) of the N in these polymers were nonhydrolyzable,The role of Maillard reacion in the formation of nonhydrolyzable nitrogen in soil organic matter is discussed.

  14. Avoidance Reaction of Penaeus Chinensis to Heavy Metals (Pb, Cr,Zn) and Heavy Metal Mixtures (Pb-Cr, Pb-Zn)

    Institute of Scientific and Technical Information of China (English)

    陈民山

    2001-01-01

    Study on the avoidance response of Penaeus chinensis to heavy metals (Pb, Cr, Zn) and heavy metal mixtures (Pb-Cr, Pb-Zn) is carred out using a Y-model avoidance apparatus. The concentrations calculated to induce 50% avoidance rate byPenaeus chinensis are 11.4, 33.2 and 238. 1 mg/L for Pb, Cr and Zn, respectively. Mixtures of Pb-Cr and Pb-Zn produce additive effect in the avoidance test using Penaeus chinesis. But when the mixed Pb-Zn solution has 0.5 toxic unit Pb and 0.5 toxic unit Zn, the mixture seems to have synergistic effect.

  15. Kinetic modeling of acrylamide formation in aqueous reaction systems and potato crisps : Text & Figures

    NARCIS (Netherlands)

    Knol, J.J.

    2008-01-01

    Acrylamide can be formed in foods that have undergone a high temperature treatment (>120 °C) such as French fries, crisps, coffee and bread, due to the Maillard reaction. The evidence of acrylamide in foods posing a risk for different types of cancer has been strengthened. Mitigation of

  16. Kinetic modeling of acrylamide formation in aqueous reaction systems and potato crisps : Text & Figures

    NARCIS (Netherlands)

    Knol, J.J.

    2008-01-01

    Acrylamide can be formed in foods that have undergone a high temperature treatment (>120 °C) such as French fries, crisps, coffee and bread, due to the Maillard reaction. The evidence of acrylamide in foods posing a risk for different types of cancer has been strengthened. Mitigation of acrylamid

  17. Photooxidation of farnesene mixtures in the presence of NOx: Analysis of reaction products and their implication to ambient PM2.5

    Data.gov (United States)

    U.S. Environmental Protection Agency — Chemical analysis of SOA produced from the irradiation of a mixture of α/β-farnesene/NOx was conducted in a 14.5 cubic meter smog chamber. SOA collected on...

  18. Chemical reaction and separation method

    NARCIS (Netherlands)

    Jansen, J.C.; Kapteijn, F.; Strous, S.A.

    2005-01-01

    The invention is directed to process for performing a chemical reaction in a reaction mixture, which reaction produces water as by-product, wherein the reaction mixture is in contact with a hydroxy sodalite membrane, through which water produced during the reaction is removed from the reaction mixtu

  19. Una llamada al lector: los huecos en la escritura de Chantal Maillard

    Directory of Open Access Journals (Sweden)

    Anna Tort Pérez

    2015-12-01

    Full Text Available http://dx.doi.org/10.5007/1807-9288.2015v11n2p18 En este artículo, se analiza la escritura de Chantal Maillard en relación con la importancia de los huecos en la estructura textual de la obra. Partiendo de la posición del lector, se revisan los rasgos de hipertextualidad presentes en la escritura maillardiana. Desde la convicción de que el espacio es un elemento que genera sentido, tanto en cada uno de los libros como en la red trazada entre todos ellos, se interpreta el quehacer textual de la autora como una llamada al lector. Este, como exigencia de la propia disposición de la obra, se ve impelido a configurar una nueva realidad a partir, no tanto de lo dicho, sino de lo sugerido; no tanto de lo presente, sino de lo ausente.

  20. Reaction mechanisms and kinetics of processing glucose, xylose and glucose-xylose mixtures under hot compressed water conditions for predicting bio-crude composition

    DEFF Research Database (Denmark)

    Grigoras, Ionela; Toor, Saqib Sohail; Rosendahl, Lasse Aistrup

    Mechanisms for bio-crude formation during the conversion of glucose, xylose and glucose-xylose mixtures as biomass model compounds under hot compressed water conditions are investigated. Studies in literature have shown that the diverse products formed at the early stages of glucose or xylose con...

  1. Differential determination of a mixture of vitamin A-[beta]-carotene by potentiometric titration utilizing a reaction with N-bromosuccinimide and iodine

    National Research Council Canada - National Science Library

    Junko MOTONAKA; Yuji MISHIMA; Sanae IKEDA; Nobuyuki TANAKA

    1995-01-01

      A rapid method is proposed for the determination of an unstable vitamin A-β-carotene mixture by the potentiometric argentimetric titration of stable iodide ions and bromide ions, liberated in proportion to the amount of vitamin A-β...

  2. Opening talk given by M. Dominique Maillard at the professional colloquium of the French federation of fuels; Discours d'ouverture prononce par M. Dominique Maillard au colloque professionnel de la Federation francaise des combustibles et des carburants

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    This talk, given by D. Maillard, general director of energy and raw materials, presents first the 2004 world situation of petroleum products in terms of prices and production capacity and the role played by investment funds in this situation. Then, he proposes some short-term actions to be implemented: encouraging investment efforts in exploration-production, preservation of strategic stocks, influencing the consumers behaviour in order to reduce the demand, assigning exceptional financial helps to professionals whose activity is threatened by the rise of petroleum products price. In the last part of his talk, D. Maillard wants to reassure the petroleum products retailers about the evolutions of their profession in this context of prices inflation. The government will harmonize the tax discrepancies between natural gas and gas oil and will ensure the equilibrium between the different forms of trade in the petroleum products sector in order to maintain a sound competition between the small and big retailers. (J.S.)

  3. Mixture formation and pre-reaction in an injection jet in Diesel engine boundary conditions; Gemischbildung und Vorreaktionen in einem Einspritzstrahl unter dieselmotorischen Randbedingungen

    Energy Technology Data Exchange (ETDEWEB)

    Eisele, G.; Koss, H.J.; Knoche, K.F.

    1993-12-31

    To examine the mixture formation and combustion, fuel is injected in Diesel engine boundary conditions in a pressure chamber. Spectroscopic methods permit the noncontact investigation with high spatial and temporal resolution of the physical and chemical processes. The jet of an excimer laser is focussed in the injection jet for this purpose. The local mixture compostion is determined from the Raman spectra, and fluorescence spectra permit one to obtain qualitative information on the appearance and distribution of the OH and NH radicals in the injection jet. For example, it was found that with a chamber temperature of 500 C, the first clear OH fluorescence occurs about 1.8 ms after the start of injection at the edge of the jet in the area of lean mixture. (orig.) [Deutsch] Zur Untersuchung der Gemischbildung und Verbrennung wird Kraftstoff unter dieselmotorischen Randbedingungen in einer Druckkammer eingespritzt. Spektroskopische Methoden erlauben die beruehrungslose und zudem oertlich und zeitlich hochaufgeloeste Untersuchung der physikalischen und chemischen Vorgaenge. Dazu wird der Strahl eines Excimerlasers in den Einspritzstrahl fokussiert. Aus Ramanspektren laesst sich die lokale Gemischzusammensetzung bestimmen, Fluoreszenzspektren erlauben qualitative Aussagen ueber Auftreten und Verteilung der OH- und NH-Radikale im Einspritzstrahl. So zeigt sich zum Beispiel, dass bei einer Kammertemperatur von 500 C die ersten deutlichen OH-Fluoreszenzen ca. 1,8 ms nach Einspritzbeginn am Strahlrand im Bereich mageren Gemisches auftreten (orig.)

  4. Effect of amino acids on the formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in creatinine/phenylalanine and creatinine/phenylalanine/4-oxo-2-nonenal reaction mixtures.

    Science.gov (United States)

    Zamora, Rosario; Alcón, Esmeralda; Hidalgo, Francisco J

    2013-12-15

    2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) formation in mixtures of creatinine, phenylalanine, amino acids and 4-oxo-2-nonenal was studied, to analyse the role of amino acids on the generation of this heterocyclic aromatic amine. When oxidised lipid was absent, cysteine, serine, aspartic acid, threonine, asparagine, tryptophan, tyrosine, proline, and methionine increased significantly (p amino acids produced reactive carbonyls that converted phenylalanine into phenylacetaldehyde as a key step in the formation of PhIP. When oxidised lipid was present, amino acids competed with phenylalanine for the lipid, and amino acid degradation products were formed, among which alpha-keto acids seemed to play a role in these reactions. These results suggest that PhIP can be produced by several alternative reaction pathways from all major food components, including amino acids and lipids, in addition to carbohydrates.

  5. Produtos da reação de Maillard em alimentos: implicações para a saúde

    Directory of Open Access Journals (Sweden)

    Julianna Shibao

    2011-12-01

    Full Text Available A reação de Maillard é uma reação de escurecimento não enzimático que pode ocorrer em alimentos e em organismos vivos. Esta revisão tem como objetivo analisar a formação e o papel dos produtos originados a partir da reação de Maillard e seus efeitos na saúde. Para isso foram realizados levantamentos bibliográficos nas bases da área, sem restrição de data. Os resultados da revisão apontam que produtos carbonílicos inter-mediários da reação de Maillard e da peroxidação reagem facilmente com grupamentos aminas de proteínas e ácidos nucleicos, levando a modificações biológicas que podem resultar em complicações observadas no diabetes, aterosclerose e doenças neurodegenerativas. O consumo de produtos da reação de Maillard aumentou nas últimas décadas, devido ao aumento do consumo de alimentos industrializados que, em geral, sofreram processamento térmico. Essas substâncias são biodisponíveis em alguma proporção e, embora ainda não haja consenso sobre os possíveis efeitos deletérios à saúde decorrentes de sua ingestão, a comunidade científica tem expressado preocupação com as implicações em processos patológicos de que participam. Diante desses achados, ressalta-se a necessidade de estimar o consumo dos produtos da reação de Maillard, principalmente por populações vulneráveis, como crianças e diabéticos, a fim de, se necessário, estabelecer consumos diários aceitáveis e ampliar o conhecimento com vistas ao estabelecimento, no futuro, de limites para a indústria de alimentos.

  6. Spectrophotometric study on the proton transfer reaction between 2-amino-4-methylpyridine with 2,6-dichloro-4-nitrophenol in methanol, acetonitrile and the binary mixture 50% methanol + 50% acetonitrile

    Science.gov (United States)

    Al-Ahmary, Khairia M.; Habeeb, Moustafa M.; Al-Obidan, Areej H.

    2016-02-01

    Proton transfer reaction between 2-amino-4-methylpyridine (2AMP) as the proton acceptor with 2,6-dichloro-4-nitrophenol (DCNP) as the proton donor has been investigated spectrophotometrically in methanol (MeOH), acetonitrile (AN) and a binary mixture composed of 50% MeOH and 50% AN (AN-Me). The composition of the complex has been investigated utilizing Job's and photometric titration methods to be 1:1. Minimum-maximum absorbance equation has been applied to estimate the formation constant of the proton transfer reaction (KPT) where it reached high values in the investigated solvent confirming its high stability. The formation constant recorded higher value in AN compared with MeOH and mixture of AN-Me. Based on the formation of stable proton transfer complex, a sensitive spectrophotometric method was suggested for quantitative determination of 2AMP. The Lambert-Beer's law was obeyed in the concentration range 0.5-8 μg mL- 1 with small values of limits of detection and quantification. The solid complex between 2AMP with DCNP has been synthesized and characterized by elemental analysis to be 1:1 in concordant with the molecular stoichiometry in solution. Further analysis of the solid complex was carried out using infrared and 1H NMR spectroscopy.

  7. Numerical Analysis of Autoignition and Combustion of n-Butane and Air Mixture in Homogeneous-Charge Compression-Ignition Engine Using Elementary Reactions

    Science.gov (United States)

    Yamasaki, Yudai; Iida, Norimasa

    The present study focuses on clarifying the combustion mechanism of the homogeneous-charge compression-ignition (HCCI) engine in order to control ignition and combustion as well as to reduce HC and CO emissions and to maintain high combustion efficiency by calculating the chemical kinetics of elementary reactions. For the calculations, n-butane was selected as fuel since it is a fuel with the smallest carbon number in the alkane family that shows two-stage autoignition (heat release with low-temperature reaction (LTR) and with high-temperature reaction (HTR)) similarly to higher hydrocarbons such as gasoline. The CHEMKIN code was used for the calculations assuming zero dimensions in the combustion chamber and adiabatic change. The results reveal the heat release mechanism of the LTR and HTR, the control factor of ignition timing and combustion speed, and the condition need to reduce HC and CO emissions and to maintain high combustion efficiency.

  8. New Reaction Routes for Preparing Single-Phase Tl2CaBa2Cu2O8 and Tl2Ca2Ba2Cu3O10 Powders from Stoichiometric Mixtures

    Science.gov (United States)

    Wu, Nae-Lih; Lee, Sern-Nan; Yao, Yeong Der

    1989-08-01

    Single-phase Tl2CaBa2Cu2O8 and Tl2Ca2Ba2Cu3O10 powders were prepared from stoichiometric mixtures by the following two reactions: (1) CaBa2CuO4+Tl2O3+CuO→Tl2CaBa2Cu2O8 and (2) Tl2CaBa2Cu2O8+CaO+CuO→Tl2Ca2Ba2Cu3O10. Single-phase powders were obtained at 830°C for the first reaction, and at 870°C for the second reaction. At these temperatures, the extent of powder melting and the rate of Tl loss were small. Powders thus prepared showed superconducting temperatures (both the zero-resistivity and diamagnetic onset temperatures) of above 110 K and a saturation Meissner effect of 20% of (-1/4π) at a field of 20 G.

  9. Adsorption and chemical reaction of gaseous mixtures of hydrogen chloride and water on aluminum oxide and application to solid-propellant rocket exhaust clouds

    Science.gov (United States)

    Cofer, W. R., III; Pellett, G. L.

    1978-01-01

    Hydrogen chloride (HCl) and aluminum oxide (Al2O3) are major exhaust products of solid rocket motors (SRM). Samples of calcination-produced alumina were exposed to continuously flowing mixtures of gaseous HCl/H2O in nitrogen. Transient sorption rates, as well as maximum sorptive capacities, were found to be largely controlled by specific surface area for samples of alpha, theta, and gamma alumina. Sorption rates for small samples were characterized linearly with an empirical relationship that accounted for specific area and logarithmic time. Chemisorption occurred on all aluminas studied and appeared to form from the sorption of about a 2/5 HCl-to-H2O mole ratio. The chemisorbed phase was predominantly water soluble, yielding chloride/aluminum III ion mole ratios of about 3.3/1 suggestive of dissolved surface chlorides and/or oxychlorides. Isopiestic experiments in hydrochloric acid indicated that dissolution of alumina led to an increase in water-vapor pressure. Dissolution in aqueous SRM acid aerosol droplets, therefore, might be expected to promote evaporation.

  10. Investigation of the behavior of Pt-Ru mixtures with nafion in the oxygen reduction reaction; Investigacion del comportamiento de mezclas de Pt-Ru con nafion en la reaccion de reduccion de oxigeno

    Energy Technology Data Exchange (ETDEWEB)

    Enriquez M, O

    2005-07-01

    In this work the electrochemical study for the reduction reaction of oxygen (RRO) of ruthenium, platinum and two mixtures of Pt-Ru (10:90) and Pt-Ru (50:50); to this last its were determined the kinetic and electrochemical parameters. The platinum used was analytical platinum and the ruthenium it was obtained of the decarboxylation of 200 mg of ruthenium dode carbonyl with 200 ml of 1-2 dichlorobenzene under a reflux system by 20 hours with agitation. Decanted and centrifuged by 30 minutes, the obtained ruthenium was washed with ether and it was evaporated for it later use. The material was characterized by means of X-ray diffraction, elementary analysis, scanning electron microscopy and infrared spectroscopy. To determine the optimum quantity of nafion to be deposited on the catalytic material, they were carried out tests with different quantities deposited on the electrodes with 1, 2, 4 and 8 {mu}L, giving better result 2 {mu}L for that it was opted for to work with this proportion in the mixtures. The electrochemical performance of 2 ruthenium relationships and platinum 0.05 mg - 0.45 mg and 0.25 mg - 0.25 mg respectively were studied with a potentiostat galvanostat EG and G Princeton Applied Research model 273a; it was found that the electrode with the mixture of 0.25 mg of platinum with 0.25 mg of ruthenium has a bigger response of current intensity after to deposit the nafion in the surface. The electro active area was determined carrying out recurrent voltametry to different scanning velocities (5, 10, 20, 30, 40, 50, 60, 70 and 80 mV/s) in the non faraday region with a value of 0.2082 cm{sup 2}. The mixture Pt-Ru (50:50) it presents a first order kinetics for the RRO and it is carried out via 4 electrons; the study of current density in function of the temperature presents values of 0.47 {+-} 0.3 for the charge transfer coefficient, of 118 mV/decade for the Tafel slope and it has an activation energy of 0.39 eV. (Author)

  11. Catalyst mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Masel, Richard I.; Rosen, Brian A.

    2017-02-14

    Catalysts that include at least one catalytically active element and one helper catalyst can be used to increase the rate or lower the overpotential of chemical reactions. The helper catalyst can simultaneously act as a director molecule, suppressing undesired reactions and thus increasing selectivity toward the desired reaction. These catalysts can be useful for a variety of chemical reactions including, in particular, the electrochemical conversion of CO.sub.2 or formic acid. The catalysts can also suppress H.sub.2 evolution, permitting electrochemical cell operation at potentials below RHE. Chemical processes and devices using the catalysts are also disclosed, including processes to produce CO, OH.sup.-, HCO.sup.-, H.sub.2CO, (HCO.sub.2).sup.-, H.sub.2CO.sub.2, CH.sub.3OH, CH.sub.4, C.sub.2H.sub.4, CH.sub.3CH.sub.2OH, CH.sub.3COO.sup.-, CH.sub.3COOH, C.sub.2H.sub.6, O.sub.2, H.sub.2, (COOH).sub.2, or (COO.sup.-).sub.2, and a specific device, namely, a CO.sub.2 sensor.

  12. Microwave-assisted isomerisation of lactose to lactulose and Maillard conjugation of lactulose and lactose with whey proteins and peptides.

    Science.gov (United States)

    Nooshkam, Majid; Madadlou, Ashkan

    2016-06-01

    Lactose was isomerised to lactulose by microwave heating and purified by a methanolic procedure to a product with approximately 72% lactulose content. Afterwards, lactose and the lactulose-rich product (PLu) were conjugated with either whey protein isolate (WPI) or its antioxidant hydrolysate (WPH) through microwaving. Lactose had a higher Maillard reactivity than PLu, and WPH was more reactive than WPI. The browning intensity of WPI-sugar systems was however higher than that of WPH-sugar pairs. Atomic force microscopy showed larger (up to ≈103 nm) particles for WPI-PLu conjugates compared to WPH-PLu counterparts (up to ≈39 nm). The Maillard conjugation progressively increased the radical-scavenging activity of WPI/WPH-sugar pairs with increasing conjugation time and improved the foaming properties of WPI and WPH. The WPI/WPH-sugar conjugates showed higher solubility and emulsification index than unreacted counterpart pairs. For native WPI, β-lactoglobulin was not degraded by in vitro gastric digestion, whereas for WPH-PLu conjugates degraded completely.

  13. Glycation of human cortical and cancellous bone captures differences in the formation of Maillard reaction products between glucose and ribose.

    Science.gov (United States)

    Sroga, Grażyna E; Siddula, Alankrita; Vashishth, Deepak

    2015-01-01

    To better understand some aspects of bone matrix glycation, we used an in vitro glycation approach. Within two weeks, our glycation procedures led to the formation of advanced glycation end products (AGEs) at the levels that corresponded to approx. 25-30 years of the natural in vivo glycation. Cortical and cancellous bones from human tibias were glycated in vitro using either glucose (glucosylation) or ribose (ribosylation). Both glucosylation and ribosylation led to the formation of higher levels of AGEs and pentosidine (PEN) in cancellous than cortical bone dissected from all tested donors (young, middle-age and elderly men and women). More efficient glycation of bone matrix proteins in cancellous bone most likely depended on the higher porosity of this tissue, which facilitated better accessibility of the sugars to the matrix proteins. Notably, glycation of cortical bone from older donors led to much higher AGEs levels as compared to young donors. Such efficient in vitro glycation of older cortical bone could result from aging-related increase in porosity caused by the loss of mineral content. In addition, more pronounced glycation in vivo would be driven by elevated oxidation processes. Interestingly, the levels of PEN formation differed pronouncedly between glucosylation and ribosylation. Ribosylation generated very high levels of PEN (approx. 6- vs. 2.5-fold higher PEN level than in glucosylated samples). Kinetic studies of AGEs and PEN formation in human cortical and cancellous bone matrix confirmed higher accumulation of fluorescent crosslinks for ribosylation. Our results suggest that in vitro glycation of bone using glucose leads to the formation of lower levels of AGEs including PEN, whereas ribosylation appears to support a pathway toward PEN formation. Our studies may help to understand differences in the progression of bone pathologies related to protein glycation by different sugars, and raise awareness for excessive sugar supplementation in food and drinks.

  14. Faox enzymes inhibited Maillard reaction development during storage both in protein glucose model system and low lactose UHT milk

    NARCIS (Netherlands)

    Troise, A.D.; Dathan, N.A.; Fiore, A.; Roviello, G.; Fiore, Di A.; Caira, S.; Cuollo, M.; Simone, De G.; Fogliano, V.; Monti, S.M.

    2014-01-01

    Fructosamines, also known asAmadori products, are formed by the condensation of glucose with the amino group of amino acids or proteins. These compounds are precursors of advanced glycation end products (AGEs) that can be formed either endogenously during aging and diabetes, and exogenously in heat-

  15. Faox enzymes inhibited Maillard reaction development during storage both in protein glucose model system and low lactose UHT milk

    NARCIS (Netherlands)

    Troise, A.D.; Dathan, N.A.; Fiore, A.; Roviello, G.; Fiore, Di A.; Caira, S.; Cuollo, M.; Simone, De G.; Fogliano, V.; Monti, S.M.

    2014-01-01

    Fructosamines, also known asAmadori products, are formed by the condensation of glucose with the amino group of amino acids or proteins. These compounds are precursors of advanced glycation end products (AGEs) that can be formed either endogenously during aging and diabetes, and exogenously in heat-

  16. Effect of ultrasonic pretreatment on physicochemical characteristics and rheological properties of soy protein/sugar Maillard reaction products

    National Research Council Canada - National Science Library

    Zhao, Cheng-Bin; Zhou, Lin-Yi; Liu, Jin-Yang; Zhang, Yao; Chen, Yang; Wu, Fei

    2016-01-01

    ... °C for 15 min with ultrasonic pretreatment (ultrasonic power of 200 W) for 20 min. Effect of ultrasonic pretreatment on physicochemical characteristics and rheological properties of SPI/sugar MRPs was investigated...

  17. Limited hydrolysis combined with controlled Maillard-induced glycation does not reduce immunoreactivity of soy protein for all sera tested.

    Science.gov (United States)

    Walter, Jordan; Greenberg, Yana; Sriramarao, P; Ismail, Baraem P

    2016-12-15

    Combining proteolysis and Maillard-induced glycation was investigated to reduce the immunoreactivity of soy protein. Soy protein was hydrolyzed by Alcalase following response surface methodology utilizing three variables, temperature, time, and enzyme:substrate ratio, with the degree of hydrolysis (DH) and percent reduction in immunoreactivity as response variables. Western blots and ELISA were used to evaluate immunoreactivity using human sera. Data were fitted to appropriate models and prediction equations were generated to determine optimal hydrolysis conditions. The hydrolysate produced under optimized conditions was subjected to glycation with dextran. Hydrolysate produced under optimal conditions had 7.8% DH and a percent reduction in immunoreactivity ranging from 20% to 52%, depending on the sera used. Upon glycation, immunoreactivity was further reduced only when using serum that had the highest soy-specific IgE. This work revealed limitations and provided premises for future studies intended to prove the potency of the combined modification approach to produce a hypoallergenic protein ingredient.

  18. Effect of heavy metals and phenol on bacterial decolourisation and COD reduction of sucrose-aspartic acid Maillard product

    Institute of Scientific and Technical Information of China (English)

    Sangeeta Yadav; Ram Chandra

    2013-01-01

    Melanodins are amino-carbonyl complex,predominantly present in sugarcane molasses based distillery wastewater as major source of colourant.The microbial decolourisation of melanoidin is a challenge due to its binding property with other co-pollutants of distillery waste.Results revealed that the presence of Zn2+ (2.00-20.00 mg/L) in melanoidin solution (1200 mg/L) stimulated the bacterial growth and sucrose-aspartic acid Maillard product (SAA) decolourisation as compared to control,while Fe3+ and Mn2+ at the same concentration inhibited the process.However,the presence of phenol (100 mg/L) along with Zn2+,Fe3+ and Mn2+ suppressed the bacterial growth,SAA decolourisation and MnP activity.The shrinkage and reduced number of bacterial cell count at higher concentration of heavy metals in presence of phenol was also observed under scanning electron microscope.

  19. Mixture Density Mercer Kernels

    Data.gov (United States)

    National Aeronautics and Space Administration — We present a method of generating Mercer Kernels from an ensemble of probabilistic mixture models, where each mixture model is generated from a Bayesian mixture...

  20. Non-enzymatic modification of aminophospholipids by carbonyl-amine reactions.

    Science.gov (United States)

    Naudí, Alba; Jové, Mariona; Ayala, Victòria; Cabré, Rosanna; Portero-Otín, Manuel; Pamplona, Reinald

    2013-02-05

    Non-enzymatic modification of aminophospholipids by lipid peroxidation-derived aldehydes and reducing sugars through carbonyl-amine reactions are thought to contribute to the age-related deterioration of cellular membranes and to the pathogenesis of diabetic complications. Much evidence demonstrates the modification of aminophospholipids by glycation, glycoxidation and lipoxidation reactions. Therefore, a number of early and advanced Maillard reaction-lipid products have been detected and quantified in different biological membranes. These modifications may be accumulated during aging and diabetes, introducing changes in cell membrane physico-chemical and biological properties.

  1. Mass spectrometric study of three-body ion-molecule clustering reactions of C pH q+ ions with N 2 or CH 4 in N 2CH 4 mixtures

    Science.gov (United States)

    Speller, C. V.; Vacher, J. R.; Duc, E.; Fitaire, M.

    1995-02-01

    Thermochemical data for several ion-molecule clustering of hydrocarbon ions with N 2 or CH 4 were obtained from clustering equilibria studies in gas mixtures irradiated by α-particles. High-pressure mass spectrometry was used to determine the enthalpy and entropy changes of clustering ( ΔH° and ΔS°, respectively) for the reactions X +(N 2) n-1 +2N 2⇋ X +(N 2) n+N 2 with X = CH 5, n = 1-2; X = C 2H 5, n = 1-4; and X = C 3H 7, n = 1. For X = CH 5, the values ( ΔH°; ΔS°) are found to be (-6.8 kcal mol -1; -19.7 cal mol -1 K -1) for n = 1, and (-5.3 kcal mol -1; -15.9 cal mol -1K -1) for n = 2. For X = C 2H 5, ( ΔH°; ΔS°) = (-6.9 kcal mol -1; -18.2 cal mol -1 K -1), for n = 1, and (-4.6 kcal mol -1; -20.8 cal mol -1 K -1) for n = 2. From the equilibrium measurements at 129 K, estimates of the thermochemical values could be obtained for n = 3-4. The results obtained for the free energy, ΔG°, were -1.4 kcal mol -1 for n = 3, and -1.1 kcal mol -1 for n = 4. For X = C 3H 7 we found ΔG° = -0.7 kcal mol -1 at 213 K. The association reactions X ++2CH 4⇋ X +(CH 4)+CH 4 with X = CH 5, C 2H 5, C 2H 7, and C 3H 7 were also studied, resulting in free energy values at 206 K of -3.1, -1.9, -0.5 and -1.3 kcal mol -1, respectively. The results for CH 5, C 2H 5 and C 3H 7 are compared with previously reported measurements.

  2. Optimal mixture experiments

    CERN Document Server

    Sinha, B K; Pal, Manisha; Das, P

    2014-01-01

    The book dwells mainly on the optimality aspects of mixture designs. As mixture models are a special case of regression models, a general discussion on regression designs has been presented, which includes topics like continuous designs, de la Garza phenomenon, Loewner order domination, Equivalence theorems for different optimality criteria and standard optimality results for single variable polynomial regression and multivariate linear and quadratic regression models. This is followed by a review of the available literature on estimation of parameters in mixture models. Based on recent research findings, the volume also introduces optimal mixture designs for estimation of optimum mixing proportions in different mixture models, which include Scheffé’s quadratic model, Darroch-Waller model, log- contrast model, mixture-amount models, random coefficient models and multi-response model.  Robust mixture designs and mixture designs in blocks have been also reviewed. Moreover, some applications of mixture desig...

  3. Solid state reaction synthesis of Ba0.75Sr0.25AlSi2O8 - Al2O3 ceramic composites from mechanically activated precursor mixtures

    Directory of Open Access Journals (Sweden)

    Ramos-Ramírez, M. V.

    2014-06-01

    Full Text Available Ceramic composites with Ba0.75Sr0.25AlSi2O8 (SBAS/Al2O3 mass ratios of: 1 90/10, 2 70/30, and 3 50/50, were in situ synthesized at 900-1500 °C/5 h from mixtures of fly ash, BaCO3, SrCO3 and Al2O3. The green mixtures were mechanically activated for 0, 4 and 8 h in an attrition mill. As a result, the solid state reactions were faster and occurred at lower temperatures. Only the SBAS and Al2O3 phases were obtained at 1300-1500°C, with the SBAS present in composition 1 achieving full conversion from its hexagonal (Hexacelsian into its monoclinic (Celsian form, with or without milling. The higher nominal SBAS content of composition 1 facilitated in it the mentioned conversion, in comparison with the other two studied compositions, which required to be mechanically activated for times that increased with increasing Al2O3 content, in order to attain in them similarly high Hexacelsian to Celsian conversions. The mechanical properties of the synthesized materials increased with increasing milling time, sintering temperature and Al2O3 content. Thus, the best mechanical properties were obtained for composition 3 milled for 8 h and sintered at 1500 °C.Compósitos cerámicos con relaciones Ba0.75Sr0.25AlSi2O8 (SBAS/Al2O3 en masa de: 1 90/10, 2 70/30, y 3 50/50, fueron sintetizados in situ a 900-1500 °C/5 h usando mezclas de cenizas volantes, BaCO3, SrCO3 y Al2O3 . Las mezclas en verde fueron activadas mecánicamente por 0, 4 y 8 h en un molino de atrición. Como resultado, las reacciones en el estado sólido fueron más rápidas y ocurrieron a menores temperaturas. A 1300-1500°C sólo se obtuvo las fases SBAS y Al2O3 , con el SBAS presente en la composición 1 transformado completamente de su forma hexagonal (Hexacelsiana a la monoclínica (Celsiana, con o sin molienda. El mayor contenido nominal de SBAS en esa composición facilitó dicha conversión, en comparación con las otras dos composiciones estudiadas, las cuales requirieron ser activadas mec

  4. Ion-neutral reactions in the ion source of a mixture of CO2/CH3OH, CO2/C2H5OH, and CO2/2-C3H7OH by packed capillary supercritical fluid chromatography-mass spectrometry (SFC-MS).

    Science.gov (United States)

    Ekeberg, Dag; Jablonska-Jentoft, Anja M

    2007-12-01

    Ion neutral reactions in the gas phase in mixtures of ROH/CO(2), R = CH(3), C(2)H(5), and 2-C(3)H(7) were studied by supercritical fluid chromatography-mass spectrometry (SFC-MS). Three main reaction series were found for this system; ionization followed by alpha-cleavage, formation of clusters, and formation of protonated dialkyl ethers from the corresponding alcohol. The ion chemistries were similar for the three alcohols, but that of 2-propanol was somewhat more complex.

  5. Low temperature asphalt mixtures

    OpenAIRE

    Modrijan, Damjan

    2006-01-01

    This thesis presents the problem of manufacturing and building in the asphalt mixtures produced by the classical hot procedure and the possibility of manufacturing low temperature asphalt mixtures.We will see the main advantages of low temperature asphalt mixtures prepared with bitumen with organic addition Sasobit and compare it to the classical asphalt mixtures. The advantages and disadvantages of that are valued in the practical example in the conclusion.

  6. Spinodal decomposition of chemically reactive binary mixtures

    Science.gov (United States)

    Lamorgese, A.; Mauri, R.

    2016-08-01

    We simulate the influence of a reversible isomerization reaction on the phase segregation process occurring after spinodal decomposition of a deeply quenched regular binary mixture, restricting attention to systems wherein material transport occurs solely by diffusion. Our theoretical approach follows a diffuse-interface model of partially miscible binary mixtures wherein the coupling between reaction and diffusion is addressed within the frame of nonequilibrium thermodynamics, leading to a linear dependence of the reaction rate on the chemical affinity. Ultimately, the rate for an elementary reaction depends on the local part of the chemical potential difference since reaction is an inherently local phenomenon. Based on two-dimensional simulation results, we express the competition between segregation and reaction as a function of the Damköhler number. For a phase-separating mixture with components having different physical properties, a skewed phase diagram leads, at large times, to a system converging to a single-phase equilibrium state, corresponding to the absolute minimum of the Gibbs free energy. This conclusion continues to hold for the critical phase separation of an ideally perfectly symmetric binary mixture, where the choice of final equilibrium state at large times depends on the initial mean concentration being slightly larger or less than the critical concentration.

  7. Liquids and liquid mixtures

    CERN Document Server

    Rowlinson, J S; Baldwin, J E; Buckingham, A D; Danishefsky, S

    2013-01-01

    Liquids and Liquid Mixtures, Third Edition explores the equilibrium properties of liquids and liquid mixtures and relates them to the properties of the constituent molecules using the methods of statistical thermodynamics. Topics covered include the critical state, fluid mixtures at high pressures, and the statistical thermodynamics of fluids and mixtures. This book consists of eight chapters and begins with an overview of the liquid state and the thermodynamic properties of liquids and liquid mixtures, including vapor pressure and heat capacities. The discussion then turns to the thermodynami

  8. Repercusiones del consumo de mezclas calentadas de glucosa-lisina y glucosa-metionina sobre el calcio óseo Effects of intake of heated mixtures of glucose-lysine and glucose-methionine on bone calcium

    Directory of Open Access Journals (Sweden)

    C. Delgado-Andrade

    2005-02-01

    Full Text Available Durante el tratamiento térmico de los alimentos puede desarrollarse la reacción de Maillard, que tiene lugar, fundamentalmente, entre los grupos carbonilo de azúcares reductores y los grupo amino proteicos. Los productos de la reacción de Maillard (PRM pueden afectar la biodisponibilidad mineral por modificaciones de su forma físico-química en el alimento o en el lumen, alterando el proceso de absorción o su normal metabolismo. En este trabajo se estudió la influencia de PRM sobre aspectos de la biodisponibilidad del Ca in vitro e in vivo. Mezclas equimolares de glucosa-lisina (GL y glucosa-metionina (GM (40% humedad fueron calentadas a 150º C durante 90 minutos (muestras GL90 y GM90, respectivamente. La solubilidad in vitro se midió adicionando cada muestra a una solución 3,75 mM Ca con pH y fuerza iónica del intestino; tras agitación y centrifugación se determinó el calcio soluble e insoluble. Un 3% de GL90 y GM90 se añadieron individualmente a la dieta AIN93-G para la obtención de las dietas D-GL90 y D-GM90. Con ellas y con la AIN93-G, como control, se alimentaron durante 21 días tres grupos de ratas Wistar, realizándose balance de calcio en la última semana y, tras sacrificio, extracción de distintos órganos. La presencia de GM90 no afectó a la solubilidad del calcio; GL90 la disminuyó ligeramente, quedando en ambos casos más del 94% soluble. El consumo de D-GL90 y D-GM90 no modificó la biodisponibilidad del elemento, utilizándose tan eficazmente como en la dieta control (57,6 ± 1,3%, 57,8 ± 2,3% y 63,9 ± 2,6% en las dietas control, D-GL90 y D-GM90 respectivamente. Sin embargo, la ingesta de los PRM produjo cambios en el metabolismo que disminuyeron el calcio óseo, acumulándose de forma compensatoria en otros órganos.During food thermal treatment Maillard's reaction may occur, which implicates mainly the carbonyl groups of reductory sugars and amino protein groups. Maillard's reaction products (MRP may

  9. Utilização de acetochlor e atrazine aplicados em mistura de tanque com dessecantes no sistema de plantio direto Reaction of the herbicides acetochlor and atrazine applied in tank mixtures with desiccants in no-till system

    Directory of Open Access Journals (Sweden)

    Benedito N. Rodrigues

    2000-08-01

    "rolada", em qualquer tratamento; neste caso, os maiores valores foram 91% para atrazine+óleo vegetal e 90% para atrazine+glyphosate+2,4D. Na modalidade "em pé'', os maiores valores foram obtidos com atrazine+óleo vegetal (77 % e com atrazine+glyphosate+2,4D (70 %.Tank mix involving desiccants plus residual herbicides have been used by farmers in no- till system. Nevertheless, it has been commented that the residual herbicides can stay retained in the straw when used in pre-emergence in this system. The objective of this trial, was to study the reaction of the residual herbicides atrazine and acetochlor in tank mix with desiccants herbicides for corn crop in no-till system. The experiment was settled in Londrina, State of Paraná, using a randomized complete block design in a split plot arrangement. Nine treatments were located at the main plots: 1 acetochlor + glyphosate; 2 acetochlor + glyphosate + 2,4D; 3 acetochlor + paraquat; 4 acetochlor + paraquat + 2,4D; 5 atrazine + glyphosate; 6 atrazine + glyphosate + 2,4D; 7 atrazine + paraquat; 8 atrazine + vegetal oil; 9 check without herbicides. Two modalities of herbicides application of herbicides were tested in split plots: 1 application on a "non rolled" cover crops; 2 application on a "rolled"cover crops. The winter cover crops were a mixture of plants formed by Avena strigosa Schreb plus Vicia sativa L. The best control of Brachiaria plantaginea, Euphorbia heterophylla and Bidens pilosa was obtained with atrazine treatments. In general terms, the treatments "non rolled" were better than the "rolled" ones for weed control. The chromatografic analysis of the soil sampled from the plots before and after 41 mm of a rainfall that occured 24 h after application of the herbicides, showed that less than 6% of the acetochlor applied was detected in soil in both modalities of application. In respect to atrazine however, more than 78% of the total applied was detected in soil after the rain in the "rolled" modality in any

  10. Hyphenated techniques in speciation analysis of polyoxometalates: identification of individual [PMo12-xVxO40](-3-x) (x = 1-3) in the reaction mixtures by high performance liquid chromatography and atomic emission spectrometry with inductively coupled plasma.

    Science.gov (United States)

    Shuvaeva, O V; Zhdanov, A A; Romanova, T E; Abramov, P A; Sokolov, M N

    2017-03-14

    Unambiguous identification of polyoxometalate (POM) species generated in self-assembly reactions in solution is rather problematic due to close similarity of their properties such as solubility and spectral characteristics. The situation is made more complex by protonation equilibria (which can change their analytical signals) and the lack of individual compounds to serve as standards for individual members of these mixtures. In the present work a new approach to the study of such POMs has been suggested, taking molybdovanadates [PMo12-xVxO40](-3-x) as a model. The key feature of this approach consists of generation of so-called "conditional model systems" that include most of the expected components of a mixture formed by self-assembly, tracked down by reliable detection techniques, e.g., (51)V NMR-spectroscopy in this particular case. Then the proposed composition of the mixture is verified and corrected by means of high-performance liquid chromatography coupled with inductively coupled plasma atomic emission spectrometry (HPLC-ICP-AES).

  11. Perception of trigeminal mixtures.

    Science.gov (United States)

    Filiou, Renée-Pier; Lepore, Franco; Bryant, Bruce; Lundström, Johan N; Frasnelli, Johannes

    2015-01-01

    The trigeminal system is a chemical sense allowing for the perception of chemosensory information in our environment. However, contrary to smell and taste, we lack a thorough understanding of the trigeminal processing of mixtures. We, therefore, investigated trigeminal perception using mixtures of 3 relatively receptor-specific agonists together with one control odor in different proportions to determine basic perceptual dimensions of trigeminal perception. We found that 4 main dimensions were linked to trigeminal perception: sensations of intensity, warmth, coldness, and pain. We subsequently investigated perception of binary mixtures of trigeminal stimuli by means of these 4 perceptual dimensions using different concentrations of a cooling stimulus (eucalyptol) mixed with a stimulus that evokes warmth perception (cinnamaldehyde). To determine if sensory interactions are mainly of central or peripheral origin, we presented stimuli in a physical "mixture" or as a "combination" presented separately to individual nostrils. Results showed that mixtures generally yielded higher ratings than combinations on the trigeminal dimensions "intensity," "warm," and "painful," whereas combinations yielded higher ratings than mixtures on the trigeminal dimension "cold." These results suggest dimension-specific interactions in the perception of trigeminal mixtures, which may be explained by particular interactions that may take place on peripheral or central levels.

  12. A sealing mixture

    Energy Technology Data Exchange (ETDEWEB)

    Khayrullin, S.R.; Firsov, I.A.; Ongoyev, V.M.; Shekhtman, E.N.; Taskarin, B.T.

    1983-01-01

    A plugging mixture is proposed which contains triethanolamine, caustic soda, water and an additive. It is distinguished by the fact that in order to reduce the cost of the mixture while preserving its operational qualities, it additionally contains clay powder and as the additive, ground limestone with the following component ratio in percent by mass: ground limestone, 50 to 60; triethanolamine, 0.1 to 0.15; caustic soda, 2 to 3; clay powder, 8 to 10 and water the remainder. The mixture is distinguished by the fact that the ground limestone has a specific surface of 2,000 to 3,000 square centimeters per gram.

  13. Determination of peracetic acid and hydrogen peroxide in the mixture

    OpenAIRE

    Bodiroga Milanka; Ognjanović Jasminka

    2002-01-01

    Iodometric and permanganometric titrations were used for determination of peracetic acid and hydrogen peroxide (H2O2) in the mixture. Two procedures were described and compared. Titrations could be done in only one vessel, in the same reaction mixture, when iodometric titration of peracetic acid was continued after the permanganometric titration of H2O2, (procedure A). Peracetic acid and H2O2, as oxidizing agents, reacted with potassium iodide in an acid medium, evolving iodine. This reaction...

  14. Tandem mass spectrometry: analysis of complex mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Singleton, K.E.

    1985-01-01

    Applications of tandem mass spectrometry (MS/MS) for the analysis of complex mixtures results in increased specificity and selectivity by using a variety of reagent gases in both negative and positive ion modes. Natural isotopic abundance ratios were examined in both simple and complex mixtures using parent, daughter and neutral loss scans. MS/MS was also used to discover new compounds. Daughter scans were used to identify seven new alkaloids in a cactus species. Three of these alkaloids were novel compounds, and included the first simple, fully aromatic isoquinoline alkaloids reported in Cactaceae. MS/MS was used to characterize the chemical reaction products of coal in studies designed to probe its macromolecular structure. Negative ion chemical ionization was utilized to study reaction products resulting from the oxidation of coal. Possible structural units in the precursor coal were predicted based on the reaction products identified, aliphatic and aromatic acids and their anhydrides. The MS/MS method was also used to characterize reaction products resulting from coal liquefaction and/or extraction. These studies illustrate the types of problems for which MS/MS is useful. Emphasis has been placed on characterization of complex mixtures by selecting experimental parameters which enhance the information obtained. The value of using MS/MS in conjunction with other analytical techniques as well as the chemical pretreatment is demonstrated.

  15. The Kinetics of Enzyme Mixtures

    Directory of Open Access Journals (Sweden)

    Simon Brown

    2014-03-01

    Full Text Available Even purified enzyme preparations are often heterogeneous. For example, preparations of aspartate aminotransferase or cytochrome oxidase can consist of several different forms of the enzyme. For this reason we consider how different the kinetics of the reactions catalysed by a mixture of forms of an enzyme must be to provide some indication of the characteristics of the species present. Based on the standard Michaelis-Menten model, we show that if the Michaelis constants (Km of two isoforms differ by a factor of at least 20 the steady-state kinetics can be used to characterise the mixture. However, even if heterogeneity is reflected in the kinetic data, the proportions of the different forms of the enzyme cannot be estimated from the kinetic data alone. Consequently, the heterogeneity of enzyme preparations is rarely reflected in measurements of their steady-state kinetics unless the species present have significantly different kinetic properties. This has two implications: (1 it is difficult, but not impossible, to detect molecular heterogeneity using kinetic data and (2 even when it is possible, a considerable quantity of high quality data is required.

  16. Multilevel Mixture Kalman Filter

    Directory of Open Access Journals (Sweden)

    Xiaodong Wang

    2004-11-01

    Full Text Available The mixture Kalman filter is a general sequential Monte Carlo technique for conditional linear dynamic systems. It generates samples of some indicator variables recursively based on sequential importance sampling (SIS and integrates out the linear and Gaussian state variables conditioned on these indicators. Due to the marginalization process, the complexity of the mixture Kalman filter is quite high if the dimension of the indicator sampling space is high. In this paper, we address this difficulty by developing a new Monte Carlo sampling scheme, namely, the multilevel mixture Kalman filter. The basic idea is to make use of the multilevel or hierarchical structure of the space from which the indicator variables take values. That is, we draw samples in a multilevel fashion, beginning with sampling from the highest-level sampling space and then draw samples from the associate subspace of the newly drawn samples in a lower-level sampling space, until reaching the desired sampling space. Such a multilevel sampling scheme can be used in conjunction with the delayed estimation method, such as the delayed-sample method, resulting in delayed multilevel mixture Kalman filter. Examples in wireless communication, specifically the coherent and noncoherent 16-QAM over flat-fading channels, are provided to demonstrate the performance of the proposed multilevel mixture Kalman filter.

  17. Mixtures Estimation and Applications

    CERN Document Server

    Mengersen, Kerrie; Titterington, Mike

    2011-01-01

    This book uses the EM (expectation maximization) algorithm to simultaneously estimate the missing data and unknown parameter(s) associated with a data set. The parameters describe the component distributions of the mixture; the distributions may be continuous or discrete. The editors provide a complete account of the applications, mathematical structure and statistical analysis of finite mixture distributions along with MCMC computational methods, together with a range of detailed discussions covering the applications of the methods and features chapters from the leading experts on the subject

  18. Nuclear fuel alloys or mixtures and method of making thereof

    Science.gov (United States)

    Mariani, Robert Dominick; Porter, Douglas Lloyd

    2016-04-05

    Nuclear fuel alloys or mixtures and methods of making nuclear fuel mixtures are provided. Pseudo-binary actinide-M fuel mixtures form alloys and exhibit: body-centered cubic solid phases at low temperatures; high solidus temperatures; and/or minimal or no reaction or inter-diffusion with steel and other cladding materials. Methods described herein through metallurgical and thermodynamics advancements guide the selection of amounts of fuel mixture components by use of phase diagrams. Weight percentages for components of a metallic additive to an actinide fuel are selected in a solid phase region of an isothermal phase diagram taken at a temperature below an upper temperature limit for the resulting fuel mixture in reactor use. Fuel mixtures include uranium-molybdenum-tungsten, uranium-molybdenum-tantalum, molybdenum-titanium-zirconium, and uranium-molybdenum-titanium systems.

  19. Thermodynamic Analysis of Chemically Reacting Mixtures and Their Kinetics: Example of a Mixture of Three Isomers.

    Science.gov (United States)

    Pekař, Miloslav

    2016-10-18

    Thermodynamics provides consequences of and restrictions on chemically reacting mixtures, particularly their kinetics, which have not been fully explored. Herein, a comprehensive thermodynamic analysis is illustrated for a reacting mixture of three isomers. The rate equation is first derived on the basis of the results of nonequilibrium continuum thermodynamics of linear fluids, and is then subjected to the requirement of consistency with entropic inequality (the second law). This consistency test involves the correct representation of the reaction rate as a function of affinities. It is shown that entropic inequality restricts the signs or values of coefficients in the constitutive equations for reaction rates/rate constants. The use of reverse rate constants and the identification of thermodynamic and kinetic equilibrium constants are not necessary in this approach. Although the presented thermodynamic analysis works only for independent reactions, the rates of dependent reactions are not excluded from having effects on kinetics. It is shown that the rates of dependent reactions are combined from the rates of independent reactions differently than dependent reactions are combined from independent reactions. The results are compared to the classical mass-action rate equations, and new restrictions on the values of the classical rate constants are derived.

  20. Study on alkali reaction of nickel slag and nickel slag-sand mixtures in Ningde region%宁德地区镍渣及其复掺砂的碱活性研究

    Institute of Scientific and Technical Information of China (English)

    吴世兴

    2016-01-01

    The article discussed the alkali reaction of nickel slag and aggregate mixed with natural sand through petrographic method and al -kali-aggregate reaction .The results showed that the nickel slag could not be used as aggregate in concrete because of its potential alkali -aggregate damage .The research also showed that the potential alkali -aggregate damage could be reduced by mixing natural sand , and there was no alkali-aggregate harm to the aggregate when the natural sand content was not less than 50%.%本文通过岩相法和快速碱-骨料反应法研究了镍渣及其复掺砂的碱活性。研究表明镍渣具有潜在碱-骨料反应危害,不宜单独用作混凝土骨料。通过复掺标准砂可以降低碱-骨料反应危害,实验表明当标准砂掺量不低于50%时,复掺砂不存在碱-骨料反应危害。

  1. Comparative formation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in creatinine/phenylalanine and creatinine/phenylalanine/4-oxo-2-nonenal reaction mixtures.

    Science.gov (United States)

    Zamora, Rosario; Alcón, Esmeralda; Hidalgo, Francisco J

    2013-05-01

    The comparative formation of the heterocyclic aromatic amine 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in both creatinine/phenylalanine (CRN/Phe) and creatinine/phenylalanine/4-oxo-2-nonenal (CRN/Phe/ON) systems was studied to analyse the ability of lipid-derived reactive carbonyls to promote PhIP formation. Although PhIP was produced to some extent in the CRN/Phe system, the presence of the oxidized lipid increased considerably the amount of PhIP produced. This increase seemed to be a consequence of the decrease in the E(a) of the reaction when the lipid was present, which diminished from 112.9 to 80.9 kJ/mol. On the other hand, the addition of the lipid did not seem to produce PhIP by an alternative mechanism because PhIP was formed analogously in both CRN/Phe and CRN/Phe/ON systems as a function of pH, creatinine concentration, phenylalanine concentration, time, temperature, oxygen concentration in the reaction atmosphere, and the addition of different amounts of ammonia. All these results suggest that the ability of lipid oxidation products to produce PhIP is related to their capacity to induce the Strecker degradation of phenylalanine to phenylacetaldehyde. Therefore, any other reactive carbonyl compound that can produce the Strecker degradation of phenylalanine should also be considered as a potential inducer of PhIP formation under appropriate conditions.

  2. Studies of the mechanism of the olefin metathesis reaction and the process of active site formation on photoreduced molybdenum-silicate catalysts. 2. Productive and degenerative metathesis of C/sub 2/H/sub 4/-C/sub 2/D/sub 4/ and C/sub 3/H/sub 6/-C/sub 3/D/sub 6/ mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Elev, I.V.; Shelimov, B.N.; Kazanskii, V.B.

    1987-10-01

    The specific catalytic activity of photoreduced Mo/sup 4 +//SiO/sub 2/ samples has been compared for productive and degenerate metathesis reactions of C/sub 3/H/sub 6/-C/sub 3/D/sub 6/ and C/sub 2/H/sub 4/-C/sub 2/D/sub 4/ mixtures. It has been found, that, under comparable conditions, the rate of degenerate metathesis of ethylene is 4-5 times slower than the rate of productive metathesis of propylene, although the rate of degenerate metathesis of propylene is 5 x 10/sup 3/-10/sup 4/ times greater than its rate of productive metathesis. Based on these results, it is concluded that degenerate metathesis of propylene occurs via the involvement of secondary (ethylidene) carbenes.

  3. Mixtures and interactions

    NARCIS (Netherlands)

    Groten, J.P.

    2000-01-01

    Drinking water can be considered as a complex mixture that consists of tens, hundreds or thousands of chemicals of which the composition is qualitatively and quantitatively not fully known. From a public health point of view it is most relevant to answer the question of whether chemicals in drinking

  4. 利用美拉德反应生产板栗咖啡的工艺研究%Chestnut coffee production by use of Maillard reaction process

    Institute of Scientific and Technical Information of China (English)

    李婷; 徐秀忠; 宋广磊; 巫建民; 楼珉

    2010-01-01

    研究了板栗的护色工艺,并对4种护色方法进行了比较,采用0.25%柠檬酸+0.20%Vc+0.25%壳聚糖+0.35%NaCl护色剂进行护色获得的板栗质量较好.在板栗护色的基础上,采用正交实验设计,研究了利用板栗生产板栗"咖啡"的工艺,结果显示采用加热时间30 min、甘氨酸1.2%、葡萄糖6%、料水比25%时获得的板栗"咖啡"风味、色泽、质感等最佳,效果最好.

  5. 氧化牛油Maillard反应制备牛肉香精研究%Study on synthisis of beef flavor by Maillard reaction using oxidized tallow

    Institute of Scientific and Technical Information of China (English)

    龚钢明; 肖作兵; 荣绍丰; 蔡宝国; 张伟健

    2008-01-01

    以牛油为原料经高温氧化,再用Maillard反应制备牛肉香精,考察了氧化温度、时间、空气流量与牛油氧化后的酸值、过氧化值和茴香胺值变化的关系,牛油氧化程度不同对牛内香精风味形成的影响.采用感观评价法对产品风味进行评定.实验结果表明:牛油在温度120℃,时间4h和空气流量0.6 L/min条件下氧化,产生的酸值为2.05 mgKOH/g脂肪,过氧化值为128.25 meq/kg脂肪、茴香胺值42.60,该氧化牛油经Maillard反应形成香精风味最具有浓郁的牛肉香精特征.用GC/MS对Maillard产物中的挥发性物质进行分析,鉴定出12种主要风味物质.

  6. Preparation of process meat flavoring by Maillard reaction of hydrolyzing soybean protein%水解大豆蛋白制备热反应肉味香精

    Institute of Scientific and Technical Information of China (English)

    华婧; 孙莹; 张晓鸣

    2007-01-01

    采用硫酸水解大豆蛋白制备肉类香精,通过正交实验和感官评定得出用15%的硫酸在固液比1∶5加热反应2.5h后的蛋白水解液,进行美拉德反应,可获得最佳肉类风味.通过大豆蛋白水解液的氨基酸和分子量分布分析,发现水解液中主要参与美拉德反应的为2~8个氨基酸残基的小肽和少量游离氨基酸.采用SPME方法,经GC-MS分析分离鉴定出43种挥发性化合物,主要包括呋喃类含氧化合物,噻吩、硫醇类含硫化合物,占所分离鉴定化合物的28%,所鉴定出的杂环化合物是呈现肉类风味的关键化合物.

  7. Phenolic compounds reduce formation of N(ε)-(carboxymethyl)lysine and pyrazines formed by Maillard reactions in a model bread system.

    Science.gov (United States)

    Mildner-Szkudlarz, Sylwia; Siger, Aleksander; Szwengiel, Artur; Przygoński, Krzysztof; Wojtowicz, Elżbieta; Zawirska-Wojtasiak, Renata

    2017-09-15

    This study had the objective of determining the antiglycation activity of phenolic compounds (PCs) ((+)-catechin, quercetin, gallic, ferulic, and caffeic acids) added to a model bread with regards to the inhibition of N(ε)-(carboxymethyl)lysine (CML) formation. PCs were found to significantly reduce CML (31.77%-87.56%), even at the lowest concentration, with the exception of ferulic acid (FA). The strongest inhibitory effect of FA (∼62%) appeared when concentration was increased to 1.0g/100g of flour. The available lysine losses (0.00%-90.51%) showed a significant correlation (0.853-0.990) with effectiveness of CML inhibition, except in the case of samples with FA. (+)-Catechin reduced CML levels the most, probably due to its structure-antioxidant activity relationship, its thermal stability (∼51% loss), and its reactivity with ε-lysine side chains (∼40.77% loss). Although the bread supplemented with PCs contained low levels of CML, this process may adversely affect bread flavor, reducing the formation of pyrazines (1.10%-80.77%). Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. 亚硫酸盐抑制糖汁美拉德反应的研究%Study on inhibiting maillard reaction in sugar juice by sulphite

    Institute of Scientific and Technical Information of China (English)

    李林; 卢家炯

    2001-01-01

    本文通过试验添加不同亚硫酸盐研究了美拉德褐变抑制的规律. 研究表明,在一定条件下亚硫酸盐能有效抑制美拉德反应,降低色值.通过紫外分光光度计研究了吸收光谱和吸光度的变化.并通过对试验数据的计算,得出了抑制剂加入量和脱色率的关系曲线.通过紫外分光光度计研究了吸收光谱和吸光度的变化.对抑制美拉德反应可能的机理进行了讨论.

  9. The Glaser–Hay reaction

    DEFF Research Database (Denmark)

    Vilhelmsen, Mie Højer; Jensen, Jonas; Tortzen, Christian

    2013-01-01

    . This unfavorable change in reaction profile could be avoided by adding molecular sieves to the reaction mixture, thereby removing the water that is accumulated from the air and produced in the reaction in which dioxygen acts as the oxidizing agent. Not unexpectedly, the stirring rate, and hence uptake of air (O2...... on the scope of this reaction by using both 13C NMR and UV/Vis spectroscopic methods. The former method was used to study the kinetics of the coupling of aryl-substituted alkynes as the aryl carbon resonances of the reactants and products have similar NOEs and relaxation times. The reaction was found...

  10. Determination of the mixture in a reaction of glycerol with hydrochloric acid by gas chromatography%气相色谱法测定甘油与盐酸反应过程的混合物

    Institute of Scientific and Technical Information of China (English)

    尤小姿; 李华荣; 罗正鸿

    2009-01-01

    采用气相色谱方法分析了甘油与盐酸反应过程中的主要物质. 使用KB-WAX毛细管柱及FID检测器, 以乙二醇作内标和甲醇定容, 并用内标法计算. 结果表明, 在程序升温下, 气相色谱内标法能使GLY, DCP, CPD等几种物质达到基线分离, 该方法能满足测试要求.%In this paper, a simple gas chromatographic method for the identification of glycerol (GLY), 1,3-dichloropropanol-2-propanol,(DCP) and 3-chloro-1,2-propandiol (CPD) in GLY chlorination reaction is described. The results are detected by KB-WAX capillary column with a flame ionization detector (FID) and calculated by an internal stand method. Glycol is used as an internal standard, and the samples are diluted with methanol. This method is simple, rapid and the results are reliable.

  11. Pointer Sentinel Mixture Models

    OpenAIRE

    Merity, Stephen; Xiong, Caiming; Bradbury, James; Socher, Richard

    2016-01-01

    Recent neural network sequence models with softmax classifiers have achieved their best language modeling performance only with very large hidden states and large vocabularies. Even then they struggle to predict rare or unseen words even if the context makes the prediction unambiguous. We introduce the pointer sentinel mixture architecture for neural sequence models which has the ability to either reproduce a word from the recent context or produce a word from a standard softmax classifier. O...

  12. Essays on Finite Mixture Models

    NARCIS (Netherlands)

    A. van Dijk (Bram)

    2009-01-01

    textabstractFinite mixture distributions are a weighted average of a ¯nite number of distributions. The latter are usually called the mixture components. The weights are usually described by a multinomial distribution and are sometimes called mixing proportions. The mixture components may be the

  13. Essays on Finite Mixture Models

    NARCIS (Netherlands)

    A. van Dijk (Bram)

    2009-01-01

    textabstractFinite mixture distributions are a weighted average of a ¯nite number of distributions. The latter are usually called the mixture components. The weights are usually described by a multinomial distribution and are sometimes called mixing proportions. The mixture components may be the sam

  14. Mixtures of truncated basis functions

    DEFF Research Database (Denmark)

    Langseth, Helge; Nielsen, Thomas Dyhre; Rumí, Rafael

    2012-01-01

    In this paper we propose a framework, called mixtures of truncated basis functions (MoTBFs), for representing general hybrid Bayesian networks. The proposed framework generalizes both the mixture of truncated exponentials (MTEs) framework and the mixture of polynomials (MoPs) framework. Similar...

  15. Separating Underdetermined Convolutive Speech Mixtures

    DEFF Research Database (Denmark)

    Pedersen, Michael Syskind; Wang, DeLiang; Larsen, Jan

    2006-01-01

    a method for underdetermined blind source separation of convolutive mixtures. The proposed framework is applicable for separation of instantaneous as well as convolutive speech mixtures. It is possible to iteratively extract each speech signal from the mixture by combining blind source separation...

  16. Toxicological evaluation of chemical mixtures

    NARCIS (Netherlands)

    Feron, V.J.; Groten, J.P.

    2002-01-01

    This paper addresses major developments in the safety evaluation of chemical mixtures during the past 15 years, reviews today's state of the art of mixture toxicology, and discusses challenges ahead. Well-thought-out tailor-made mechanistic and empirical designs for studying the toxicity of mixtures

  17. Solid state reaction synthesis of Ba{sub 0}.75Sr{sub 0}.25AlSi{sub 2}O{sub 8} - Al{sub 2}O{sub 3} ceramic composites from mechanically activated precursor mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Ramos-Ramirez, M. V.; Lopez-Cuevas, J.; Rodriguez-Galicia, J. L.; Rendon-Angeles, J. C.

    2014-10-01

    Ceramic composites with Ba{sub 0}.75Sr{sub 0}.25AlSi{sub 2}O{sub 8} (SBAS)/Al{sub 2}O{sub 3} mass ratios of: 1) 90/10, 2) 70/30, and 3) 50/50, were in situ synthesized at 900-1500 degree centigrade/5 h from mixtures of fly ash, BaCO{sub 3}, SrCO{sub 3} and Al{sub 2}O{sub 3}. The green mixtures were mechanically activated for 0, 4 and 8 h in an attrition mill. As a result, the solid state reactions were faster and occurred at lower temperatures. Only the SBAS and Al{sub 2}O{sub 3} phases were obtained at 1300-1500 degree centigrade, with the SBAS present in composition 1 achieving full conversion from its hexagonal (Hexacelsian) into its monoclinic (Celsian) form, with or without milling. The higher nominal SBAS content of composition 1 facilitated in it the mentioned conversion, in comparison with the other two studied compositions, which required to be mechanically activated for times that increased with increasing Al{sub 2}O{sub 3} content, in order to attain in them similarly high Hexacelsian to Celsian conversions. The mechanical properties of the synthesized materials increased with increasing milling time, sintering temperature and Al{sub 2}O{sub 3} content. Thus, the best mechanical properties were obtained for composition 3 milled for 8 h and sintered at 1500 degree centigrade. (Author)

  18. Modeling the kinetics nonenzymatic browning reactions and rheological behavior in the termal process of fruit juices and pulps

    Directory of Open Access Journals (Sweden)

    Damian Manayay

    2010-06-01

    Full Text Available In the manufacture of fruit juices and pulps, is of paramount importance to refer to non-enzymatic browning and rheological behavior. The non-enzymatic browning is a phenomenon of darkening of a purely chemical (Braverman, 1980, is characterized by the presence of brown polymers called melanoidins, generated by the Maillard reaction or condensation of melanoidins, the caramelization and degradation of acid ascorbic, while the rheological behavior is define as the proportion deformation of the material when exposed to shear stress (σ caused by a rheometer (Muller, 1978; Ibarz, 2005. Modeling studies of colour formation and definition of rheological behavior, considered in this review, aimed at the conclusion of the existence of a zero kinetic and first order respectively, and the most influential factors with the reactions are mainly Maillard, temperature, amino acids presence, water activity and pH, while the rheological behavior is affected by temperature, solid concentration and particles size that make up the suspension in the specific case of the pulps.

  19. Mixture Based Outlier Filtration

    Directory of Open Access Journals (Sweden)

    P. Pecherková

    2006-01-01

    Full Text Available Success/failure of adaptive control algorithms – especially those designed using the Linear Quadratic Gaussian criterion – depends on the quality of the process data used for model identification. One of the most harmful types of process data corruptions are outliers, i.e. ‘wrong data’ lying far away from the range of real data. The presence of outliers in the data negatively affects an estimation of the dynamics of the system. This effect is magnified when the outliers are grouped into blocks. In this paper, we propose an algorithm for outlier detection and removal. It is based on modelling the corrupted data by a two-component probabilistic mixture. The first component of the mixture models uncorrupted process data, while the second models outliers. When the outlier component is detected to be active, a prediction from the uncorrupted data component is computed and used as a reconstruction of the observed data. The resulting reconstruction filter is compared to standard methods on simulated and real data. The filter exhibits excellent properties, especially in the case of blocks of outliers. 

  20. Concomitant variables in finite mixture models

    NARCIS (Netherlands)

    Wedel, M

    The standard mixture model, the concomitant variable mixture model, the mixture regression model and the concomitant variable mixture regression model all enable simultaneous identification and description of groups of observations. This study reviews the different ways in which dependencies among

  1. Test Reactions to Study Efficiency of

    OpenAIRE

    Jasińska Magdalena

    2015-01-01

    Effects of mixing on the course of fast chemical reactions are relatively well understood, especially in homogeneous systems. This enables to design and operate chemical reactors with the goal to achieve a high yield of a desired product and use systems of complex reactions as a chemical probe (chemical test reactions) to identify progress of mixing and quality of mixture. Recently, a number of studies have focused on the application of chemical test reactions to identify energy efficiency of...

  2. Study on Mai l lard Reaction Conditions of Mushroom Hydrolysate%香菇水解液的美拉德反应条件研究

    Institute of Scientific and Technical Information of China (English)

    顾宗珠; 沈健; 王瑶

    2014-01-01

    Take mushroom enzymatic solution and glucose as main substrate to prepare Maillard reac-tion products.Through single factor and orthogonal experiments,the effect of microwave heating on the browning degree of Maillard reaction is investigated.The results show that the degree of brown-ing is optimal when glucose addition amount is 10%,the initial pH value of mushroom hydrolysate is adjusted to 9,the heating time is 4 min,and the microwave power is 800 W.The reaction product with sensory evaluation has unique flavor of sauce.%以香菇酶解液和葡萄糖为主要底物制备美拉德反应产物。通过单因素和正交实验,考察了微波加热对美拉德反应褐变程度的影响。结果表明:葡萄糖添加量为10%,香菇水解液初始 pH 值调整为9,加热时间为4 min,微波功率为800 W时褐变程度最佳。感官评价反应产物具有独特的酱香味。

  3. Protein mixtures: interactions and gelation

    OpenAIRE

    Ersch, C.

    2015-01-01

    Gelation is a ubiquitous process in the preparation of foods. As most foods are multi constituent mixtures, understanding gelation in mixtures is an important goal in food science. Here we presented a systematic investigation on the influence of molecular interactions on the gelation in protein mixtures. Gelatin gels with added globular protein and globular protein gels with added gelatin were analyzed for their gel microstructure and rheological properties. Mixed gels with altered microstruc...

  4. Neurotoxicity of Metal Mixtures.

    Science.gov (United States)

    Andrade, V M; Aschner, M; Marreilha Dos Santos, A P

    2017-01-01

    Metals are the oldest toxins known to humans. Metals differ from other toxic substances in that they are neither created nor destroyed by humans (Casarett and Doull's, Toxicology: the basic science of poisons, 8th edn. McGraw-Hill, London, 2013). Metals are of great importance in our daily life and their frequent use makes their omnipresence and a constant source of human exposure. Metals such as arsenic [As], lead [Pb], mercury [Hg], aluminum [Al] and cadmium [Cd] do not have any specific role in an organism and can be toxic even at low levels. The Substance Priority List of Agency for Toxic Substances and Disease Registry (ATSDR) ranked substances based on a combination of their frequency, toxicity, and potential for human exposure. In this list, As, Pb, Hg, and Cd occupy the first, second, third, and seventh positions, respectively (ATSDR, Priority list of hazardous substances. U.S. Department of Health and Human Services, Public Health Service, Atlanta, 2016). Besides existing individually, these metals are also (or mainly) found as mixtures in various parts of the ecosystem (Cobbina SJ, Chen Y, Zhou Z, Wub X, Feng W, Wang W, Mao G, Xu H, Zhang Z, Wua X, Yang L, Chemosphere 132:79-86, 2015). Interactions among components of a mixture may change toxicokinetics and toxicodynamics (Spurgeon DJ, Jones OAH, Dorne J-L, Svendsen C, Swain S, Stürzenbaum SR, Sci Total Environ 408:3725-3734, 2010) and may result in greater (synergistic) toxicity (Lister LJ, Svendsen C, Wright J, Hooper HL, Spurgeon DJ, Environ Int 37:663-670, 2011). This is particularly worrisome when the components of the mixture individually attack the same organs. On the other hand, metals such as manganese [Mn], iron [Fe], copper [Cu], and zinc [Zn] are essential metals, and their presence in the body below or above homeostatic levels can also lead to disease states (Annangi B, Bonassi S, Marcos R, Hernández A, Mutat Res 770(Pt A):140-161, 2016). Pb, As, Cd, and Hg can induce Fe, Cu, and Zn

  5. Crowding in polymer-nanoparticle mixtures.

    Science.gov (United States)

    Denton, Alan R

    2014-01-01

    The cell nucleus is a highly crowded environment, filled with a multicomponent, polydisperse mixture of biopolymers and nuclear bodies dispersed in a viscous solvent. With volume fractions approaching 20%, excluded-volume interactions play a key role in determining the structure, dynamics, and function of macromolecules in vivo. Under such constraints, the ensembles of macromolecular conformations can differ substantially from those prevailing in dilute solutions. Crowding thus can affect protein and RNA folding, conformational stability, and reaction kinetics, as well as phase stability of macromolecular mixtures. From the perspective of soft matter physics, this chapter reviews recent studies on crowding in polymer-nanoparticle mixtures, seeking to demonstrate the utility of simple physical models for addressing challenging issues in cell biology. The focus is on applications of free-volume theory and Monte Carlo simulation, based on geometrical models of polymers as fluctuating spheres or ellipsoids. Ideal polymer coils respond to hard-sphere crowding agents by compactifying, reducing their radius of gyration, and becoming more spherical. At sufficiently high concentrations, polymers and crowders phase-separate. The goal of this review is to identify universal principles governing macromolecular crowding and to establish a general framework for future explorations of more realistic models that may include nonsteric (e.g., electrostatic) interactions. © 2014 Elsevier Inc. All rights reserved.

  6. Co-pyrolysis of wood biomass and synthetic polymers mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Sharypov, V.I.; Beregovtsova, N.G.; Kuznetsov, B.N.; Baryshnikov, S.V. [Institute of Chemistry and Chemical Technology SB RAS, K. Marx Str., Krasnoyarsk 660049 (Russian Federation); Cebolla, V.L. [Instituto de Carboquimica, CSIC, Zaragoza (Spain); Weber, J.V.; Collura, S.; Finqueneisel, G.; Zimny, T. [Laboratoire de Chimie et Applications, Universite de Metz, IUT, rue V. Demange, 57500 Saint Avold (France)

    2006-06-01

    The pyrolysis in a hydrogen atmosphere of pine wood and synthetic polymers (polyethylene and polypropylene) mixtures was studied in a rotating autoclave. The effects of reaction temperature, wood/polymers mixture composition and catalysts, on the mixtures conversion into liquids and gases were established and discussed. The used catalysts were pyrrhotite and haematite materials activated by mechanochemical treatment. In the co-liquefaction processes the interaction between fragments of wood and polymers thermal decomposition took place. This results in non-additive increase of the wood/polymers conversion degree by 10-15wt.% and of the yield of distillate fractions by 14-19wt.%. Iron ore materials were found catalytically active in the process of hydropyrolysis of wood/polymers mixtures. By using these catalysts a significant increase of the distillable liquids amounts (by 14-21wt.%) and a sharp decrease of olefins and cycloparaffins content (by approximately two to three times) were observed. (author)

  7. Kinetics of ozone-phenol reaction in aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, M.G.; Shambaugh, R.L.

    1982-01-01

    The kinetics of the reaction of ozone and phenol in aqueous medium was studied. The reaction was first order with respect to both ozone and phenol. The rate constant was found to increase with increase in the pH of the reaction mixture. Four different catalysts were examined for their effect on the rate of reaction. 30 refs.

  8. Thermophysical Properties of Hydrocarbon Mixtures

    Science.gov (United States)

    SRD 4 NIST Thermophysical Properties of Hydrocarbon Mixtures (PC database for purchase)   Interactive computer program for predicting thermodynamic and transport properties of pure fluids and fluid mixtures containing up to 20 components. The components are selected from a database of 196 components, mostly hydrocarbons.

  9. Evaporating Drops of Alkane Mixtures

    OpenAIRE

    Guéna, Geoffroy; Poulard, Christophe; Cazabat, Anne-Marie

    2005-01-01

    22 pages 9 figures; Alkane mixtures are model systems where the influence of surface tension gradients during the spreading and the evaporation of wetting drops can be easily studied. The surface tension gradients are mainly induced by concentration gradients, mass diffusion being a stabilising process. Depending on the relative concentration of the mixture, a rich pattern of behaviours is obtained.

  10. Protein mixtures: interactions and gelation

    NARCIS (Netherlands)

    Ersch, C.

    2015-01-01

    Gelation is a ubiquitous process in the preparation of foods. As most foods are multi constituent mixtures, understanding gelation in mixtures is an important goal in food science. Here we presented a systematic investigation on the influence of molecular interactions on the gelation in protein mixt

  11. Evaporating Drops of Alkane Mixtures

    CERN Document Server

    Gu'ena, G; Poulard, C; Cazabat, Anne-Marie; Gu\\'{e}na, Geoffroy; Poulard, Christophe

    2005-01-01

    Alkane mixtures are model systems where the influence of surface tension gradients during the spreading and the evaporation of wetting drops can be easily studied. The surface tension gradients are mainly induced by concentration gradients, mass diffusion being a stabilising process. Depending on the relative concentration of the mixture, a rich pattern of behaviours is obtained.

  12. Protein mixtures: interactions and gelation

    NARCIS (Netherlands)

    Ersch, C.

    2015-01-01

    Gelation is a ubiquitous process in the preparation of foods. As most foods are multi constituent mixtures, understanding gelation in mixtures is an important goal in food science. Here we presented a systematic investigation on the influence of molecular interactions on the gelation in protein mixt

  13. Easy and flexible mixture distributions

    DEFF Research Database (Denmark)

    Fosgerau, Mogens; Mabit, Stefan L.

    2013-01-01

    We propose a method to generate flexible mixture distributions that are useful for estimating models such as the mixed logit model using simulation. The method is easy to implement, yet it can approximate essentially any mixture distribution. We test it with good results in a simulation study...

  14. Exploring the Fate of Nitrogen Heterocycles in Complex Prebiotic Mixtures

    Science.gov (United States)

    Smith, Karen E.; Callahan, Michael P.; Cleaves, Henderson J.; Dworkin, Jason P.; House, Christopher H.

    2011-01-01

    A long standing question in the field of prebiotic chemistry is the origin of the genetic macromolecules DNA and RNA. DNA and RNA have very complex structures with repeating subunits of nucleotides, which are composed of nucleobases (nitrogen heterocycles) connected to sugar-phosphate. Due to the instability of some nucleobases (e.g. cytosine), difficulty of synthesis and instability of D-ribose, and the likely scarcity of polyphosphates necessary for the modern nucleotides, alternative nucleotides have been proposed for constructing the first genetic material. Thus, we have begun to investigate the chemistry of nitrogen heterocycles in plausible, complex prebiotic mixtures in an effort to identify robust reactions and potential alternative nucleotides. We have taken a complex prebiotic mixture produced by a spark discharge acting on a gas mixture of N2, CO2, CH4, and H2, and reacted it with four nitrogen heterocycles: uracil, 5-hydroxymethyluracil, guanine, and isoxanthopterin (2-amino-4,7-dihydroxypteridine). The products of the reaction between the spark mixture and each nitrogen heterocycle were characterized by liquid chromatography coupled to UV spectroscopy and Orbitrap mass spectrometry. We found that the reaction between the spark mixtUl'e and isoxanthopterin formed one major product, which was a cyanide adduct. 5-hydroxymethyluracil also reacted with the spark mixture to form a cyanide adduct, uracil-5-acetonitrile, which has been synthesized previously by reacting HCN with S-hydroxymethyluracil. Unlike isoxanthopterin, the chromatogram of the 5-hydroxymethyluracil reaction was much more complex with multiple products including spark-modified dimers. Additionally, we observed that HMU readily self-polymerizes in solution to a variety of oligomers consistent with those suggested by Cleaves. Guanine and uracil, the biological nucleobases, did not react with the spark mixture, even at high temperature (100 C). This suggests that there are alternative

  15. Reaction between drug substances and pharmaceutical excipients

    DEFF Research Database (Denmark)

    Larsen, Jesper; Cornett, Claus; Jaroszewski, Jerzy Witold

    2009-01-01

    The reactivity of citric acid towards drug substances in the solid state was examined using the beta-blocker carvedilol as a model compound. The reaction mixtures were analysed by LC-MS, the reaction products were isolated by preparative HPLC, and the structures were elucidated by microprobe NMR...

  16. Explodability and detonability of mixtures of hydrogen peroxide and organic matter

    NARCIS (Netherlands)

    Heemskerk, A.H.; Scholtes, J.H.G.

    1995-01-01

    The explosive properties of mixtures of hydrogen peroxide and isopropanol were determined The mixtures appear to detonate in a well-defined range of concentrations and show extremely fast reactions in an adjacent range of concentrations if initiated by shock wave stimuli. The upper boundary of organ

  17. Low temperature extraction and upgrading of oil sands and bitumen in supercritical fluid mixtures.

    Science.gov (United States)

    Brough, Sarah A; Riley, Sandra H; McGrady, G Sean; Tanhawiriyakul, Supaporn; Romero-Zerón, Laura; Willson, Christopher D

    2010-07-21

    Preliminary results are reported for the extraction and catalytic hydrocracking of Alberta bitumen and oil sands using supercritical fluid mixtures; high levels of extraction and upgrading were attained using reaction conditions significantly milder than those previously reported.

  18. The underlying toxicological mechanism of chemical mixtures: A case study on mixture toxicity of cyanogenic toxicants and aldehydes to Photobacterium phosphoreum

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Dayong [State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Department of Chemical and Environmental Engineering, Anyang Institute of Technology, Anyang 455000 (China); Lin, Zhifen, E-mail: lzhifen@tongji.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Zhou, Xianghong [Department of Public Management, Tongji University, Shanghai 200092 (China); Yin, Daqiang [Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China)

    2013-10-15

    Intracellular chemical reaction of chemical mixtures is one of the main reasons that cause synergistic or antagonistic effects. However, it still remains unclear what the influencing factors on the intracellular chemical reaction are, and how they influence on the toxicological mechanism of chemical mixtures. To reveal this underlying toxicological mechanism of chemical mixtures, a case study on mixture toxicity of cyanogenic toxicants and aldehydes to Photobacterium phosphoreum was employed, and both their joint effects and mixture toxicity were observed. Then series of two-step linear regressions were performed to describe the relationships between joint effects, the expected additive toxicities and descriptors of individual chemicals (including concentrations, binding affinity to receptors, octanol/water partition coefficients). Based on the quantitative relationships, the underlying joint toxicological mechanisms were revealed. The result shows that, for mixtures with their joint effects resulting from intracellular chemical reaction, their underlying toxicological mechanism depends on not only their interaction with target proteins, but also their transmembrane actions and their concentrations. In addition, two generic points of toxicological mechanism were proposed including the influencing factors on intracellular chemical reaction and the difference of the toxicological mechanism between single reactive chemicals and their mixtures. This study provided an insight into the understanding of the underlying toxicological mechanism for chemical mixtures with intracellular chemical reaction. - Highlights: • Joint effects of nitriles and aldehydes at non-equitoxic ratios were determined. • A novel descriptor, ligand–receptor interaction energy (E{sub binding}), was employed. • Quantitative relationships for mixtures were developed based on a novel descriptor. • The underlying toxic mechanism was revealed based on quantitative relationships. • Two

  19. Sensitivity of Some Explosive/Brine Mixtures

    Science.gov (United States)

    1980-08-01

    concentration in brine mixtures. 3 Friction test results of brine mixtures. 10 4 Thermal test results of brine mixtures. 11 Li 71 - INTRODUCTION A...also carried out on these impact insensitive mixtures. Of the seven mixtures only the 15% M28-Comp. B sample passed the thermal test , since smoking

  20. Optimal Parameters Multicomponent Mixtures Extruding

    Directory of Open Access Journals (Sweden)

    Ramil F. Sagitov

    2013-01-01

    Full Text Available Experimental research of multicomponent mixtures extruding from production wastes are carried out, unit for production of composites from different types of waste is presented. Having analyzed dependence of multicomponent mixtures extruding energy requirements on die length and components content at three values of angular rate of screw rotation, we received the values of energy requirements at optimal length of the die, angular speed and percent of binding additives.

  1. Gaussian-mixture umbrella sampling

    OpenAIRE

    Maragakis, Paul; van der Vaart, Arjan; Karplus, Martin

    2009-01-01

    We introduce the Gaussian-mixture umbrella sampling method (GAMUS), a biased molecular dynamics technique based on adaptive umbrella sampling that efficiently escapes free energy minima in multi-dimensional problems. The prior simulation data are reweighted with a maximum likelihood formulation, and the new approximate probability density is fit to a Gaussian-mixture model, augmented by information about the unsampled areas. The method can be used to identify free energy minima in multi-dimen...

  2. Analysis of asphalt mixtures on town roads

    OpenAIRE

    Glavica, Primož

    2006-01-01

    Asphalt mixtures are most commonly used composite for construction of top layers of different drive ways. By definition asphalt mixtures are composed of crushed rock, fill, bitumen and additives. Percentage of individual components wary according to the purpose asphalt mixture is to be used for. Asphalt mixtures must be capable of enduring different types of load. According to the type of load asphalt mixtures are divided into asphalt mixtures used for supporting layers and asp...

  3. Reaction Graph

    Institute of Scientific and Technical Information of China (English)

    傅育熙

    1998-01-01

    The paper proposes reaction graphs as graphical representations of computational objects.A reaction graph is a directed graph with all its arrows and some of its nodes labeled.Computations are modled by graph rewriting of a simple nature.The basic rewriting rules embody the essence of both the communications among processes and cut-eliminations in proofs.Calculi of graphs are ideentified to give a formal and algebraic account of reaction graphs in the spirit of process algebra.With the help of the calculi,it is demonstrated that reaction graphs capture many interesting aspects of computations.

  4. Free energy methods for efficient exploration of mixture posterior densities

    CERN Document Server

    Chopin, Nicolas; Stoltz, Gabriel

    2010-01-01

    Because of their multimodality, mixture posterior densities are difficult to sample with standard Markov chain Monte Carlo (MCMC) methods. We propose a strategy to enhance the sampling of MCMC in this context, using a biasing procedure which originates from computational statistical physics. The principle is first to choose a "reaction coordinate", that is, a direction in which the target density is multimodal. In a second step, the marginal log-density of the reaction coordinate is estimated; this quantity is called "free energy" in the computational statistical physics literature. To this end, we use adaptive biasing Markov chain algorithms which adapt their invariant distribution on the fly, in order to overcome sampling barriers along the chosen reaction coordinate. Finally, we perform an importance sampling step in order to remove the bias and recover the true posterior. A crucial point is the choice of the reaction coordinate. We show that a convenient and efficient reaction coordinate is the hyper-para...

  5. Shock compression of Mo-Si powder mixtures using recovery and instrumented experiments

    Science.gov (United States)

    Vandersall, Kevin S.; Thadhani, Naresh N.

    2000-04-01

    The reaction behavior of Mo-Si powder mixtures was investigated utilizing shock recovery experiments and time resolved (instrumented) measurements. Recovery experiments revealed the formation of reaction products with two distinct microstructures, suggesting product formation via "shock-induced" and "shock-assisted" reaction mechanisms. Instrumented experiments were performed using the Georgia Tech single-stage gas gun in the velocity range of 500 m/s to 1 km/s. PVDF stress gages were placed at the front and rear surfaces of the powder mixture sample, to record the input and propagated-wave profiles. The instrumented experiments allowed investigation of the crush strength and the threshold for shock-induced reaction initiation in the Mo+2Si powder mixture. Experiments performed at stresses exceeding the crush strength, showed possible evidence of reaction based on expansion observed in the pressure-volume behavior.

  6. Transesterification of waste vegetable oil under pulse sonication using ethanol, methanol and ethanol–methanol mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Guerra, Edith; Gude, Veera Gnaneswar, E-mail: gude@cee.msstate.edu

    2014-12-15

    Highlights: • Pulse sonication effect on transesterification of waste vegetable oil was studied. • Effects of ethanol, methanol, and alcohol mixtures on FAMEs yield were evaluated. • Effect of ultrasonic intensity, power density, and its output rates were evaluated. • Alcohol mixtures resulted in higher biodiesel yields due to better solubility. - Abstract: This study reports on the effects of direct pulse sonication and the type of alcohol (methanol and ethanol) on the transesterification reaction of waste vegetable oil without any external heating or mechanical mixing. Biodiesel yields and optimum process conditions for the transesterification reaction involving ethanol, methanol, and ethanol–methanol mixtures were evaluated. The effects of ultrasonic power densities (by varying sample volumes), power output rates (in W), and ultrasonic intensities (by varying the reactor size) were studied for transesterification reaction with ethanol, methanol and ethanol–methanol (50%-50%) mixtures. The optimum process conditions for ethanol or methanol based transesterification reaction of waste vegetable oil were determined as: 9:1 alcohol to oil ratio, 1% wt. catalyst amount, 1–2 min reaction time at a power output rate between 75 and 150 W. It was shown that the transesterification reactions using ethanol–methanol mixtures resulted in biodiesel yields as high as >99% at lower power density and ultrasound intensity when compared to ethanol or methanol based transesterification reactions.

  7. Communication: Control of chemical reactions using electric field gradients.

    Science.gov (United States)

    Deshmukh, Shivaraj D; Tsori, Yoav

    2016-05-21

    We examine theoretically a new idea for spatial and temporal control of chemical reactions. When chemical reactions take place in a mixture of solvents, an external electric field can alter the local mixture composition, thereby accelerating or decelerating the rate of reaction. The spatial distribution of electric field strength can be non-trivial and depends on the arrangement of the electrodes producing it. In the absence of electric field, the mixture is homogeneous and the reaction takes place uniformly in the reactor volume. When an electric field is applied, the solvents separate and the reactants are concentrated in the same phase or separate to different phases, depending on their relative miscibility in the solvents, and this can have a large effect on the kinetics of the reaction. This method could provide an alternative way to control runaway reactions and to increase the reaction rate without using catalysts.

  8. Communication: Control of chemical reactions using electric field gradients

    Science.gov (United States)

    Deshmukh, Shivaraj D.; Tsori, Yoav

    2016-05-01

    We examine theoretically a new idea for spatial and temporal control of chemical reactions. When chemical reactions take place in a mixture of solvents, an external electric field can alter the local mixture composition, thereby accelerating or decelerating the rate of reaction. The spatial distribution of electric field strength can be non-trivial and depends on the arrangement of the electrodes producing it. In the absence of electric field, the mixture is homogeneous and the reaction takes place uniformly in the reactor volume. When an electric field is applied, the solvents separate and the reactants are concentrated in the same phase or separate to different phases, depending on their relative miscibility in the solvents, and this can have a large effect on the kinetics of the reaction. This method could provide an alternative way to control runaway reactions and to increase the reaction rate without using catalysts.

  9. Quantitative mixture fraction measurements in combustion system via laser induced breakdown spectroscopy

    KAUST Repository

    Mansour, Mohy S.

    2015-01-01

    Laser induced breakdown spectroscopy (LIBS) technique has been applied to quantitative mixture fraction measurements in flames. The measured spectra of different mixtures of natural gas and air are used to obtain the calibration parameters for local elemental mass fraction measurements and hence calculate the mixture fraction. The results are compared with the mixture fraction calculations based on the ratios of the spectral lines of H/N elements, H/O elements and C/(N+O) and they show good agreement within the reaction zone of the flames. Some deviations are observed outside the reaction zone. The ability of LIBS technique as a tool for quantitative mixture fraction as well as elemental fraction measurements in reacting and non-reacting of turbulent flames is feasible. © 2014 Elsevier Ltd. All rights reserved.

  10. Continuum thermodynamics of chemically reacting fluid mixtures

    CERN Document Server

    Bothe, Dieter

    2014-01-01

    We consider viscous and heat conducting mixtures of molecularly miscible chemical species forming a fluid in which the constituents can undergo chemical reactions. Assuming a common temperature for all components, a first main aim is the derivation of a closed system of partial mass and partial momentum balances plus a common balance of internal energy. This is achieved by careful exploitation of the entropy principle which, in particular, requires appropriate definitions of absolute temperature and chemical potentials based on an adequate definition of thermal energy that excludes diffusive contributions. The latter is crucial in order to obtain a closure framework for the interaction forces between the different species. The interaction forces split into a thermo-mechanical and a chemical part, where the former turns out to be symmetric if binary interactions are assumed. In the non-reactive case, this leads to a system of Navier-Stokes type sub-systems, coupled by interspecies friction forces. For chemical...

  11. Diastereoselective Ugi reaction for the synthesis of unnatural amino esters

    Directory of Open Access Journals (Sweden)

    Rafael Oliveira Rocha

    2012-06-01

    Full Text Available Multicomponent Reactions (MCR are useful reactions to obtain complex products by the simple mixture of 3 or more reactants. The classic Ugi reaction (4-UCR involves a mixture of an amine, aldehyde, isocyanide and a carboxylic acid, giving peptoides as products. Some modifications of this reaction have been reported, among which the use of amino acids and Lewis acids, such as titanium (IV chloride, to induce stereoselectivity in good ratio. In this work we demonstrate the efficiency of different Lewis acids in the modified Ugi reaction and good levels of diastereoselectivity and yields in the synthesis of unnatural secondary amino esters.

  12. Compression ignition of hydrogen-containing mixtures in shock tubes

    Science.gov (United States)

    Medvedev, S. P.; Gelfand, B. E.; Khomik, S. V.; Agafonov, G. L.

    2010-12-01

    The state of the art of the problem of discrepancy between the values measured in shock tubes and calculated for the delay of ignition of hydrogen-containing systems has been analyzed. It is shown that in the low-temperature region the off-design appearance of reaction sites leads to the propagation of a flame in a mixture heated by a reflected shock wave. The parameter of the time of mixture combustion in a deflagration regime has been introduced and the use of it together with the calculated delay in self-ignition for delimitation and classification of thermal and gas-dynamic phenomena on compression ignition of hydrogen-containing mixtures in shock tubes has been suggested.

  13. Marangoni Convection in Binary Mixtures

    CERN Document Server

    Zhang, J; Oron, A; Behringer, Robert P.; Oron, Alexander; Zhang, Jie

    2006-01-01

    Marangoni instabilities in binary mixtures are different from those in pure liquids. In contrast to a large amount of experimental work on Marangoni convection in pure liquids, such experiments in binary mixtures are not available in the literature, to our knowledge. Using binary mixtures of sodium chloride/water, we have systematically investigated the pattern formation for a set of substrate temperatures and solute concentrations in an open system. The flow patterns evolve with time, driven by surface-tension fluctuations due to evaporation and the Soret effect, while the air-liquid interface does not deform. A shadowgraph method is used to follow the pattern formation in time. The patterns are mainly composed of polygons and rolls. The mean pattern size first decreases slightly, and then gradually increases during the evolution. Evaporation affects the pattern formation mainly at the early stage and the local evaporation rate tends to become spatially uniform at the film surface. The Soret effect becomes i...

  14. Mixtures of skewed Kalman filters

    KAUST Repository

    Kim, Hyoungmoon

    2014-01-01

    Normal state-space models are prevalent, but to increase the applicability of the Kalman filter, we propose mixtures of skewed, and extended skewed, Kalman filters. To do so, the closed skew-normal distribution is extended to a scale mixture class of closed skew-normal distributions. Some basic properties are derived and a class of closed skew. t distributions is obtained. Our suggested family of distributions is skewed and has heavy tails too, so it is appropriate for robust analysis. Our proposed special sequential Monte Carlo methods use a random mixture of the closed skew-normal distributions to approximate a target distribution. Hence it is possible to handle skewed and heavy tailed data simultaneously. These methods are illustrated with numerical experiments. © 2013 Elsevier Inc.

  15. Kinetic Study of the Heck Reaction: An Interdisciplinary Experiment

    Science.gov (United States)

    Gozzi, Christel; Bouzidi, Naoual

    2008-01-01

    The aim of this experiment is to study and calculate the kinetic constant of a Heck reaction: the arylation of but-3-en-2-ol by iodobenzene catalyzed by palladium acetate in presence of triethylamine in DMF. The reaction leads to a mixture of two ketones. Students use GC analysis to quantify reagents and products of reaction. They control the…

  16. The pH Value of Fungicide, Insecticide and Mineral Fertilizer Mixtures Depending on Water Quality

    Directory of Open Access Journals (Sweden)

    Dušanka Inđić

    2008-01-01

    Full Text Available The paper deals with the effect of water quality on the pH value of fungicides, insecticides, mineral fertilizers and their mixtures. The fungicides propineb (Antracol WP-70 and mancozeb (Dithane M-70, insecticides pirimiphos-methyl (Actellic-50 and imidacloprid(Confidor 200-SL, several fertilizers (Ferticare I, Ferticare II, Ferticare III and Wuxal Super and their mixtures were analyzed for pH value under laboratory conditions using a potentiometric pH meter. Measurements were made directly after preparation or mixing with tap and well water and 24 hours later. Tap water exhibited a neutral reaction. A slightly alkaline reaction of well water was mostlikely due to high ammonium content. The suspensions of Antracol WP-70 exhibited slightly alkaline reactions with both water types during 24 hours. The spray liquids of Dithane M-70 mixed with tap or well water had neutral reaction after preparation and slightly alkaline reaction after 24 hours. The emulsions of Actellic-50 showed neutral reaction with both water types, followed by a pH increase in tap water after 24 hours. The solutions of Confidor200-SL had a slightly alkaline reaction after mixing and the pH value increased with both water types after 24 hours. It is therefore recommended to apply these insecticides directly after preparation. Mineral fertilizers considerably reduced pH values of the fungicide and insecticide components in double and triple mixtures, especially Ferticare nutrients which had a moderately acid reaction. Wuxal Super had a neutral reaction with both water types.The mixtures with well water increased pH values, which indicates that water pH does affect the pH value of the mixture. Both individual fertilizers and all mixtures (double and triple with Ferticare had pH values between 2.4 and 6, which allows their active liquids to be stored for 12 to 24 hours. The suspensions (Antracol WP-70, double and triple mixtures, emulsions (Actellic-50 and Actellic-50+Wuxal Super

  17. Biocatalytic Resolution of Enantiomeric Mixtures of 1-Aminoethanephosphonic Acid

    Directory of Open Access Journals (Sweden)

    Paweł Kafarski

    2011-07-01

    Full Text Available Several fungal strains, namely Bauveria bassiana, Cuninghamella echinulata, Aspergillus fumigatus, Penicillium crustosum and Cladosporium herbarum, were used as biocatalysts to resolve racemic mixtures of 1-aminoethanephosphonic acid using L/D amino acid oxidase activity. The course of reaction was analyzed by 31P-NMR in the presence of cyclodextrin used as chiral discriminating agent. The best result (42% e.e of R-isomer was obtained with a strain of Cuninghamella echinulata.

  18. Biocatalytic resolution of enantiomeric mixtures of 1-aminoethanephosphonic acid.

    Science.gov (United States)

    Brzezińska-Rodak, Małgorzata; Klimek-Ochab, Magdalena; Zymańczyk-Duda, Ewa; Kafarski, Paweł

    2011-07-14

    Several fungal strains, namely Bauveria bassiana, Cuninghamella echinulata, Aspergillus fumigatus, Penicillium crustosum and Cladosporium herbarum, were used as biocatalysts to resolve racemic mixtures of 1-aminoethanephosphonic acid using L/D amino acid oxidase activity. The course of reaction was analyzed by 31P-NMR in the presence of cyclodextrin used as chiral discriminating agent. The best result (42% e.e of R-isomer) was obtained with a strain of Cuninghamella echinulata.

  19. Taylor dispersion analysis of mixtures.

    Science.gov (United States)

    Cottet, Hervé; Biron, Jean-Philippe; Martin, Michel

    2007-12-01

    Taylor dispersion analysis (TDA) is a fast and simple method for determining hydrodynamic radii. In the case of sample mixtures, TDA, as the other nonseparative methods, leads to an average diffusion coefficient on the different molecules constituting the mixture. We set in this work the equations giving, on a consistent basis, the average values obtained by TDA with detectors with linear response functions. These equations confronted TDA experiments of sample mixtures containing different proportions of a small molecule and a polymer standard. Very good agreement between theory and experiment was obtained. In a second part of this work, on the basis of monomodal or bimodal molar mass distributions of polymers, the different average diffusion coefficients corresponding to TDA were compared to the z-average diffusion coefficient (D(z)) obtained from dynamic light scattering (DLS) experiments and to the weight average diffusion coefficient (D(w)). This latter value is sometimes considered as the most representative of the sample mixture. From these results, it appears that, for monomodal distribution and relatively low polydispersity (I = 1.15), the average diffusion coefficient generally derived from TDA is very close to Dw. However, for highly polydisperse samples (e.g., bimodal polydisperse distributions), important differences could be obtained (up to 35% between TDA and D(w)). In all the cases, the average diffusion coefficient obtained by TDA for a mass concentration detector was closer to the Dw value than the z-average obtained by DLS.

  20. Two types of radicals in whole milk powder. Effect of lactose crystallization, lipid oxidation, and browning reactions.

    Science.gov (United States)

    Thomsen, Marianne K; Lauridsen, Lene; Skibsted, Leif H; Risbo, Jens

    2005-03-09

    Whole milk powder was stored in closed vials at 60 degrees C to induce crystallization of lactose within a short time scale. After an induction period of 3-4 days simultaneous crystallization of lactose, increase of water activity, formation of browning products, and increase of radical content took place. Radicals detected before lactose crystallization were characterized by a narrow ESR spectrum (g = 2.006) and could be depleted by removal of oxygen and therefore were assigned to oxidation processes. Late-stage radicals present after crystallization of lactose gave much wider spectra (g = 2.0048) and were independent of oxygen availability and assigned to late-stage Maillard reaction products. The study indicates that the processes of lactose crystallization, browning, and formation of radical species (g = 2.0048) are strongly coupled, while lipid oxidation is less dependent on the other processes.

  1. catalysis of the michael reactions by n,n'-dimethylaminopropyl ...

    African Journals Online (AJOL)

    a

    In each case the templates were recovered and reused in ... reaction mixture that had pH similar to that of the catalyst-water suspension, the pH of the mixture was ... The shoulders are likely to be due to residual -OEt groups which have been.

  2. Formation of flavor components by the reaction of amino acid and carbonyl compounds in mild conditions.

    Science.gov (United States)

    Pripis-Nicolau, L; de Revel, G; Bertrand, A; Maujean, A

    2000-09-01

    This work describe products of reactions between four alpha-dicarbonyl compounds (diacetyl, pentan-2,3-dione, glyoxal, and methylglyoxal) or two alpha-hydroxy ketones, (acetoine and acetol) and amino acids present in wines. The results shows the formation of odorous products or strong-smelling additives resulting from the Maillard and Strecker reaction in a primarily aqueous medium, at low temperature and low pH ( approximately pH 3.5) of the wine. GC/FID, GC/FPD, GC/NPD and GC/MS techniques were used. The olfactive characteristics of the products are described. In the presence of sulfur amino acids and in particular cysteine, many products were formed with a heterocycle production such as pyrazines and methylpyrazines, methylthiazoles, acetylthiazoles, acetylthiazolines, acetylthiazolidines, trimethyloxazole, and dimethylethyloxazoles. These various compounds present odors of sulfur, cornlike, pungent, nut, popcorn, roasted hazelnut, toasted, roasted, and ripe fruits. The chemical conditions of the model reactions are specified. The influence of temperature and pH on the reactions in the presence of cysteine were also studied.

  3. Natural Inhibitors of Maillard Browning

    Science.gov (United States)

    2013-12-01

    Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 TASTE INHIBITION DISCOLORATION FOOD PRESERVATION... wine , and many other consumable items. They are known for their antioxidant properties and have varying molecular structures with a similar backbone

  4. The effect of carbon nanotubes on chiral chemical reactions

    Science.gov (United States)

    Rance, Graham A.; Miners, Scott A.; Chamberlain, Thomas W.; Khlobystov, Andrei N.

    2013-02-01

    The intrinsic helicity of carbon nanotubes influences the formation of chiral molecules in chemical reactions. A racemic mixture of P and M enantiomers of nanotubes affects the enantiomeric excess of the products of the autocatalytic Soai reaction proportional to the amount of nanotubes added in the reaction mixture. An intermediate complex formed between the nanotube and the organometallic reagent is essential and explains the observed correlation between the enantiomeric distribution of products and the curvature of the carbon nanostructure. This Letter establishes a key mechanism for harnessing the helicity of nanoscale carbon surfaces for preparative organic reactions.

  5. Flows and chemical reactions in an electromagnetic field

    CERN Document Server

    Prud'homme, Roger

    2014-01-01

    This book - a sequel of previous publications 'Flows and Chemical Reactions', 'Chemical Reactions Flows in Homogeneous Mixtures' and 'Chemical Reactions and Flows in Heterogeneous Mixtures' - is devoted to flows with chemical reactions in the electromagnetic field. The first part, entitled basic equations, consists of four chapters. The first chapter provides an overview of the equations of electromagnetism in Minkowski spacetime. This presentation is extended to balance equations, first in homogeneous media unpolarized in the second chapter and homogeneous fluid medium polarized in the thir

  6. Local fluctuations in solution mixtures

    Science.gov (United States)

    Ploetz, Elizabeth A.; Smith, Paul E.

    2011-01-01

    An extension of the traditional Kirkwood-Buff (KB) theory of solutions is outlined which provides additional fluctuating quantities that can be used to characterize and probe the behavior of solution mixtures. Particle-energy and energy-energy fluctuations for local regions of any multicomponent solution are expressed in terms of experimentally obtainable quantities, thereby supplementing the usual particle-particle fluctuations provided by the established KB inversion approach. The expressions are then used to analyze experimental data for pure water over a range of temperatures and pressures, a variety of pure liquids, and three binary solution mixtures – methanol and water, benzene and methanol, and aqueous sodium chloride. In addition to providing information on local properties of solutions it is argued that the particle-energy and energy-energy fluctuations can also be used to test and refine solute and solvent force fields for use in computer simulation studies. PMID:21806137

  7. Binary mixtures of chiral gases

    CERN Document Server

    Presilla, Carlo

    2015-01-01

    A possible solution of the well known paradox of chiral molecules is based on the idea of spontaneous symmetry breaking. At low pressure the molecules are delocalized between the two minima of a given molecular potential while at higher pressure they become localized in one minimum due to the intermolecular dipole-dipole interactions. Evidence for such a phase transition is provided by measurements of the inversion spectrum of ammonia and deuterated ammonia at different pressures. In particular, at pressure greater than a critical value no inversion line is observed. These data are well accounted for by a model previously developed and recently extended to mixtures. In the present paper, we discuss the variation of the critical pressure in binary mixtures as a function of the fractions of the constituents.

  8. Photochemical ozone and nitric oxide formation in air-nitrogen dioxide mixtures containing sulfur dioxide or chlorine

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, J.S.; Springer, G.S.; Stedman, D.H.

    1980-01-01

    The effects of sulfur dioxide and chlorine on ozone and nitric oxide concentrations in nitrogen dioxide-air mixtures were studied. The presence of 0-10 ppM SO/sub 2/ produced no change in the air mixture. Addition of 1-15 ppm chlorine increased the ozone concentration in the air mixture. A reaction model describing the interactions of chlorine and NO/sub 2/ is presented. (1 diagram, 6 graphs, 30 references, 3 tables)

  9. Atomistic Simulations of Bicelle Mixtures

    OpenAIRE

    Jiang, Yong; Wang, Hao; Kindt, James T.

    2010-01-01

    Mixtures of long- and short-tail phosphatidylcholine lipids are known to self-assemble into a variety of aggregates combining flat bilayerlike and curved micellelike features, commonly called bicelles. Atomistic simulations of bilayer ribbons and perforated bilayers containing dimyristoylphosphatidylcholine (DMPC, di-C14 tails) and dihexanoylphosphatidylcholine (DHPC, di-C6 tails) have been carried out to investigate the partitioning of these components between flat and curved microenvironmen...

  10. Atomistic Simulations of Bicelle Mixtures

    OpenAIRE

    Jiang, Yong; WANG, HAO; Kindt, James T.

    2010-01-01

    Mixtures of long- and short-tail phosphatidylcholine lipids are known to self-assemble into a variety of aggregates combining flat bilayerlike and curved micellelike features, commonly called bicelles. Atomistic simulations of bilayer ribbons and perforated bilayers containing dimyristoylphosphatidylcholine (DMPC, di-C14 tails) and dihexanoylphosphatidylcholine (DHPC, di-C6 tails) have been carried out to investigate the partitioning of these components between flat and curved microenvironmen...

  11. FRACTIONAL TRANSPORT OF SEDIMENT MIXTURES

    Institute of Scientific and Technical Information of China (English)

    Baosheng WU; Albert MOLINAS; Anping SHU

    2003-01-01

    A new method based on the Transport Capacity Fraction (TCF) concept is proposed to compute the fractional transport rates for nonuniform sediment mixtures in sand-bed channels. The TCF concept is derived from the understanding that the measurements and predictions of bed-material load are more accurate and reliable than the measurements and predictions of fractional loads. First the bed-material load is computed using an appropriate equation, then the fractional transport rates are determined by distributing the bed-material load into size groups through a transport capacity distribution function. For the computation of bed-material loads, the Aekers and White, Engelund and Hansen, and Yang equations are used in this study. Two new transport capacity distribution functions are developed for flows in sand-bed channels. The new expressions presented in this paper account for the sheltering and exposure effects that exist in mixtures. Comparisons with measured data show that the proposed method can significantly improve the predictions of fractional transport rates for nonuniform sediment mixtures.

  12. Capture reactions

    NARCIS (Netherlands)

    Endt, P.M.

    1956-01-01

    Capture reactions will be considered here from the viewpoint of the nuclear spectroscopist. Especially important to him are the capture of neutrons, protons, and alpha particles, which may proceed through narrow resonances, offering a well defined initial state for the subsequent deexcitation proces

  13. Allergic Reactions

    Science.gov (United States)

    ... round, they may be caused by exposure to indoor allergens such as dust mites, indoor molds or pets. Urticaria, or hives, is characterized ... home. Video: What is an allergic reaction? » Utility navigation Donate Annual meeting Browse your conditions Check pollen ...

  14. Characteristics of equilibrium reaction of zolazepam.

    Science.gov (United States)

    Hong, W H; Szulczewski, D H

    1981-06-01

    The equilibrium reaction of zolazepam, a pyrazolodiazepinone, was studied and analyzed using the approach used previously for other pyrazolodiazepinone derivatives. The intrinsic ring closure equilibrium constant for this reaction was approximately 100 times larger than that observed for pyrazolodiazepinones studied previously. This study illustrates that the diazepinone ring can dominate in equilibrium mixtures formed at pH values far below the pKa of the corresponding form.

  15. 21 CFR 82.6 - Certifiable mixtures.

    Science.gov (United States)

    2010-04-01

    ... mixture is harmless and suitable for use therein; and (3) No diluent (except resins, natural gum, pectin... mixture is for external application to shell eggs, or for use in coloring a food specified in the...

  16. Curing Reaction Model of Epoxy Asphalt Binder

    Institute of Scientific and Technical Information of China (English)

    QIAN Zhendong; CHEN Leilei; WANG Yaqi; SHEN Jialin

    2012-01-01

    In order to understand the strength developing law of the epoxy asphalt mixture,a curing reaction model of the epoxy asphalt binder was proposed based upon the thermokinetic analysis.Given some assumptions,the model was developed by applying the Kissinger law as well as Arrhenius equation,and the differential scanning calorimetry was performed for estimating the model parameters.To monitor the strength development of the epoxy asphalt mixture,a strength test program was employed and then results were compared to those produced from the proposed model.The comparative evaluation shows that a good consistency exists between the outputs from test program and the proposed model,indicating that the proposed model can be used effectively for simulating the curing reaction process for the epoxy asphalt binder and predicting the strength development for the epoxy asphalt mixture.

  17. Concentration fluctuations in non-isothermal reaction-diffusion systems. II. The nonlinear case

    NARCIS (Netherlands)

    Bedeaux, D.; Ortiz de Zárate, J.M.; Pagonabarraga, I.; Sengers, J.V.; Kjelstrup, S.

    2011-01-01

    In this paper, we consider a simple reaction-diffusion system, namely, a binary fluid mixture with an association-dissociation reaction between two species. We study fluctuations at hydrodynamic spatiotemporal scales when this mixture is driven out of equilibrium by the presence of a temperature gra

  18. Hydration study of mechanically activated mixtures of Portland cement and fly ash

    Directory of Open Access Journals (Sweden)

    GORDANA STEFANOVIC

    2007-06-01

    Full Text Available Fly ash (FA can be used in cement mixtures with certain limitations. The problem of the mentioned mixtures lies in the insufficient activity of the particles of FA in the reactions which are important for the establishment of the mechanical characteristics of cement. This is particularly true for the hydration reactions. As a result of this, cement pastes formed by mixing ash and clinker have worse characteristics compared to those of pure Portland cement (PC, especially in the early period of setting. As is well known, FA can be a good solution for the neutralization of the negative effects generated due to the creation of free Ca(OH2 during the hydration of PC, provided that the problems with the low activity of FAare overcome. For the experiments in this study, a mixture of Portland cement and fly ash was used, the content of ash in the mixture being 30 % and 50 %. Mechanical activation was performed in a vibrating ring mill. The goal of this study was to demonstrate, through experimental results, that during the mechanical activation of a PC and FAmixture, the components in the mixture which mostly affect the direction, rate and range of hydration reactions occurring in the mixture had been activated. The values of the compressive strength of the activated and non-activated mixtures and the changes of their specific surface area proved that during the grinding process, the mixture PC+FA had been mechanically activated. The highest increase of compressivestrength was achieved in the early period of setting, which indicates an improvement in the early hydration of the mixture. XRD, DTA and TG analyses showed that the alite (C3S and belite (C2S from the PC and a part of the fly ash were activated.

  19. Psychophysical studies of mixtures of tastants

    NARCIS (Netherlands)

    Graaf, de C.

    1988-01-01

    The human perception of mixtures of tastante was studied with reference to three central issues, i.e., 1) the paradigma of equiratio taste substance mixtures. as an instrument to manipulate the physical composition of tastant mixtures. This paradiama also enables the construction of psychophysical

  20. Synthesis of Ba{sub 0}.75Sr{sub 0}.25Al{sub 2}Si{sub 2}O{sub 8} - ZrO{sub 2} Ceramic Composites by Solid State Reaction of Mechanically Activated Precursor Mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Ramos-Ramirez, M. V.; Lopez-Cuevas, J.; Rodriguez-Galicia, J. L.; Rendon-Angeles, J. C.

    2014-07-01

    Precursor mixtures composed of fly ash, BaCO{sub 3}, SrCO{sub 3}, Al{sub 2}O{sub 3} and ZrO{sub 2}, were subjected to attrition milling for 0-8 h and then uniaxially pressed and sintered at 900-1500 degree centigrade/5 h, for the in situ solid state synthesis of composites with nominal Ba{sub 0}.75Sr{sub 0}.25Al{sub 2}Si{sub 2}O{sub 8} (SBAS)/ZrO{sub 2} mass ratios of: 1) 90/10, 2) 70/30, and 3) 50/50. Mechanical activation, combined with the likely generation of a considerable amount of transient liquid during sintering of the composites, notably enhanced the reactivity of the precursor mixtures. ZrO{sub 2} decreased the conversion from the hexagonal (Hexacelsian) into the monoclinic (Celsian) phases of SBAS in the composites, which became more pronounced when the content of ZrO{sub 2} was increased in the materials. Nearly full conversions could be achieved at temperatures as low as 1100 degree centigrade, by mechanically activating the precursor mixtures for times that increased with increasing content of ZrO{sub 2} in the materials. An increment in the time of mechanical activation of the precursor mixtures, as well as in their ZrO{sub 2} content and in the sintering temperature, increased the mechanical properties of the synthesized materials. Thus, the best mechanical properties were obtained for composition 3 milled for 8 h and sintered at 1500 degree centigrade. (Author)

  1. Shock compression response of Ti+B reactive powder mixtures

    Science.gov (United States)

    Gonzales, M.; Gurumurthy, A.; Kennedy, G. B.; Gokhale, A. M.; Thadhani, N. N.

    2014-05-01

    The shock compression response of Ti+2B (1:2 Ti:B stoichiometric ratio) reactive powder mixtures at ~50% theoretical material density (TMD) is investigated for shock pressures up to 5 GPa to investigate the possible shock-induced chemical reactivity of this highly exothermic mixture. The shock adiabat is produced from instrumented parallel-plate gas-gun impact experiments on encapsulated powders using poly-vinylidene fluoride (PVDF) stress gauges to measure the input and propagated stresses and wave speed in the powder. The shock compression regime is probed from crush-up to full density and onward to assess the potential onset of a shock-induced chemical reaction event in the powder mixture. A series of two-dimensional continuum meso-scale simulations on validated simulated microstructures are performed to predict the shock compression response and identify the meso-scale mechanics that are essential for reaction. The suitability of the synthetic microstructural representations is evaluated by comparing the experimental and predicted pressure traces.

  2. Operation of FCC with mixtures of regenerated and deactivated catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Spretz, R.; Sedran, U. [INCAPE, FIQ, UNL - CONICET, Instituto de Investigaciones en Catalisis y Petroquimica, Santiago del Estero 2654, 3000 Santa Fe (Argentina)

    2001-07-13

    The operation of FCC with mixtures of coked and regenerated catalyst was studied with a riser simulator reactor on two equilibrium catalysts at 550C. The coked catalysts maintain an activity level that enables them to be used in the mixtures. The catalytic performances of the regenerated catalysts were used as references against which the behaviors of 25:75 and 50:50 (coked:regenerated) mixtures were compared. It was observed that overall catoil has to be increased to maintain conversion. While the yields of gases, gasoline and LCO showed to be independent of the operative mode, changes were observed in the selectivity to light olefins C4-C6 that are mainly due to changes in the yields of the isoparaffins in the groups. In turn, these changes could be the consequence of the resulting density of paired acid sites in the zeolite components on hydrogen transfer reactions, due to the contributions by the coked and regenerated portions of catalysts. Coke yields in mixtures of coked and regenerated catalysts are not higher, which would allow increasing catalyst circulation without impacting on heat balance. The particularities of this new operation of FCC are very dependent on catalyst properties.

  3. The shock sensitivity of nitromethane/methanol mixtures

    Science.gov (United States)

    Bartram, Brian; Dattelbaum, Dana; Sheffield, Steve; Gibson, Lee

    2013-06-01

    The dilution of liquid explosives has multiple effects on detonation properties including an increase in critical diameter, spatiotemporal lengthening of the chemical reaction zone, and the development of propagating wave instabilities. Earlier detonation studies of NM/methanol mixtures have shown several effects of increasing dilution, including: 1) a continual increase in the critical diameter, 2) lowering of the Chapman-Jouguet detonation pressure, and 3) slowing of the steady detonation velocity (Koldunov et al., Comb. Expl. Shock Waves). Here, we present the results of a series of gas gun-driven plate-impact experiments to study the shock-to-detonation transition in NM/methanol mixtures. Embedded electromagnetic gauges were used to obtain in situ particle velocity wave profiles at multiple Lagrangian positions in the initiating explosive mixture. From the wave profiles obtained in each experiment, an unreacted Hugoniot locus, the initiation mechanism, and the overtake-time-to-detonation were obtained as a function of shock input condition for mixture concentrations from 100% NM to 50 wt%/50 wt% NM/methanol. Desensitization with dilution is less than expected. For example, little change in overtake time occurs in 80 wt%/20 wt% NM/methanol when compared with neat NM. Furthermore, the shock wave profiles from the gauges indicate that wave instabilities grow in as the overdriven detonation wave settles down following the shock-to-detonation transition.

  4. Ultrasonic Investigations of Molecular Interaction in Binary Mixtures of Benzyl Benzoate with Acetonitrile and Benzonitrile

    Directory of Open Access Journals (Sweden)

    N. Jaya Madhuri

    2011-01-01

    Full Text Available Ultrasonic velocity, density and viscosity have been measured in the binary mixtures of benzyl benzoate with acetonitrile, benzonitrile at three temperatures 30, 40 and 50 °C. From the experimental data, thermodynamic parameters like adiabatic compressibility, internal pressure, enthalpy, activation energy etc., were computed and the molecular interactions were predicted based on the variation of excess parameters in the mixture. Also theoretical evaluation of velocities was made employing the standard theories. CFT and NOMOTO were found to have an edge. All the three mixtures have shown out strong intermolecular interactions between the unlike molecules and endothermic type of chemical reaction.

  5. Test Reactions to Study Efficiency of

    Directory of Open Access Journals (Sweden)

    Jasińska Magdalena

    2015-06-01

    Full Text Available Effects of mixing on the course of fast chemical reactions are relatively well understood, especially in homogeneous systems. This enables to design and operate chemical reactors with the goal to achieve a high yield of a desired product and use systems of complex reactions as a chemical probe (chemical test reactions to identify progress of mixing and quality of mixture. Recently, a number of studies have focused on the application of chemical test reactions to identify energy efficiency of mixing, being a convenient way of comparing mixers and reactors in terms of their mixing efficiency. This review offers a presentation of chemical test reactions available in the literature and methods of applications of test reactions to identify the energy efficiency of mixing. Also methods to assess the extent of micromixing by measuring product distribution or segregation index, and to determine the time constant for mixing are presented for single phase homogeneous systems and two-phase liquid-liquid systems.

  6. Regimes of chemical reaction waves initiated by nonuniform initial conditions for detailed chemical reaction models.

    Science.gov (United States)

    Liberman, M A; Kiverin, A D; Ivanov, M F

    2012-05-01

    Regimes of chemical reaction wave propagation initiated by initial temperature nonuniformity in gaseous mixtures, whose chemistry is governed by chain-branching kinetics, are studied using a multispecies transport model and a detailed chemical model. Possible regimes of reaction wave propagation are identified for stoichiometric hydrogen-oxygen and hydrogen-air mixtures in a wide range of initial pressures and temperature levels, depending on the initial non-uniformity steepness. The limits of the regimes of reaction wave propagation depend upon the values of the spontaneous wave speed and the characteristic velocities of the problem. It is shown that one-step kinetics cannot reproduce either quantitative neither qualitative features of the ignition process in real gaseous mixtures because the difference between the induction time and the time when the exothermic reaction begins significantly affects the ignition, evolution, and coupling of the spontaneous reaction wave and the pressure wave, especially at lower temperatures. We show that all the regimes initiated by the temperature gradient occur for much shallower temperature gradients than predicted by a one-step model. The difference is very large for lower initial pressures and for slowly reacting mixtures. In this way the paper provides an answer to questions, important in practice, about the ignition energy, its distribution, and the scale of the initial nonuniformity required for ignition in one or another regime of combustion wave propagation.

  7. Shock induced chemical reactions in energetic structural materials

    Science.gov (United States)

    Reding, Derek J.

    Energetic structural materials (ESMs) constitute a new class of materials that provide dual functions of strength and energetic characteristics. ESMs are typically composed of micron-scale or nano-scale intermetallic mixtures or mixtures of metals and metal oxides, polymer binders, and structural reinforcements. Voids are included to produce a composite with favorable chemical reaction characteristics. In this thesis, a continuum approach is used to simulate gas-gun or explosive loading experiments where a strong shock is induced in the ESM by an impacting plate. Algorithms are developed to obtain equations of state of mixtures. It is usually assumed that the shock loading increases the energy of the ESM and causes the ESM to reach the transition state. It is also assumed that the activation energy needed to reach the transition state is a function of the temperature of the mixture. In this thesis, it is proposed that the activation energy is a function of temperature and the stress state of the mixture. The incorporation of such an activation energy is selected in this thesis. Then, a multi-scale chemical reaction model for a heterogeneous mixture is introduced. This model incorporates reaction initiation, propagation, and extent of completed reaction in spatially heterogeneous distributions of reactants. A new model is proposed for the pore collapse of mixtures. This model is formulated by modifying the Carol, Holt, and Nesterenko spherically symmetric model to include mixtures and compressibility effects. Uncertainties in the model result from assumptions in formulating the models for continuum relationships and chemical reactions in mixtures that are distributed heterogeneously in space and in numerical integration of the resulting equations. It is important to quantify these uncertainties. In this thesis, such an uncertainty quantification is investigated by systematically identifying the physical processes that occur during shock compression of ESMs which are

  8. Supercritical Water Mixture (SCWM) Experiment

    Science.gov (United States)

    Hicks, Michael C.; Hegde, Uday G.

    2012-01-01

    The subject presentation, entitled, Supercritical Water Mixture (SCWM) Experiment, was presented at the International Space Station (ISS) Increment 33/34 Science Symposium. This presentation provides an overview of an international collaboration between NASA and CNES to study the behavior of a dilute aqueous solution of Na2SO4 (5% w) at near-critical conditions. The Supercritical Water Mixture (SCWM) investigation, serves as important precursor work for subsequent Supercritical Water Oxidation (SCWO) experiments. The SCWM investigation will be performed in DECLICs High Temperature Insert (HTI) for the purpose of studying critical fluid phenomena at high temperatures and pressures. The HTI includes a completely sealed and integrated test cell (i.e., Sample Cell Unit SCU) that will contain approximately 0.3 ml of the aqueous test solution. During the sequence of tests, scheduled to be performed in FY13, temperatures and pressures will be elevated to critical conditions (i.e., Tc = 374C and Pc = 22 MPa) in order to observe salt precipitation, precipitate agglomeration and precipitate transport in the presence of a temperature gradient without the influences of gravitational forces. This presentation provides an overview of the motivation for this work, a description of the DECLIC HTI hardware, the proposed test sequences, and a brief discussion of the scientific research objectives.

  9. Atomistic simulations of bicelle mixtures.

    Science.gov (United States)

    Jiang, Yong; Wang, Hao; Kindt, James T

    2010-06-16

    Mixtures of long- and short-tail phosphatidylcholine lipids are known to self-assemble into a variety of aggregates combining flat bilayerlike and curved micellelike features, commonly called bicelles. Atomistic simulations of bilayer ribbons and perforated bilayers containing dimyristoylphosphatidylcholine (DMPC, di-C(14) tails) and dihexanoylphosphatidylcholine (DHPC, di-C(6) tails) have been carried out to investigate the partitioning of these components between flat and curved microenvironments and the stabilization of the bilayer edge by DHPC. To approach equilibrium partitioning of lipids on an achievable simulation timescale, configuration-bias Monte Carlo mutation moves were used to allow individual lipids to change tail length within a semigrand-canonical ensemble. Since acceptance probabilities for direct transitions between DMPC and DHPC were negligible, a third component with intermediate tail length (didecanoylphosphatidylcholine, di-C(10) tails) was included at a low concentration to serve as an intermediate for transitions between DMPC and DHPC. Strong enrichment of DHPC is seen at ribbon and pore edges, with an excess linear density of approximately 3 nm(-1). The simulation model yields estimates for the onset of edge stability with increasing bilayer DHPC content between 5% and 15% DHPC at 300 K and between 7% and 17% DHPC at 323 K, higher than experimental estimates. Local structure and composition at points of close contact between pores suggest a possible mechanism for effective attractions between pores, providing a rationalization for the tendency of bicelle mixtures to aggregate into perforated vesicles and perforated sheets.

  10. The Hamilton principle for fluid binary mixtures with two temperatures

    CERN Document Server

    Gouin, Henri

    2009-01-01

    For binary mixtures of fluids without chemical reactions, but with components having different temperatures, the Hamilton principle of least action is able to produce the equation of motion for each component and a balance equation of the total heat exchange between components. In this nonconservative case, a Gibbs dynamical identity connecting the equations of momenta, masses, energy and heat exchange allows to deduce the balance equation of energy of the mixture. Due to the unknown exchange of heat between components, the number of obtained equations is less than the number of field variables. The second law of thermodynamics constrains the possible expression of a supplementary constitutive equation closing the system of equations. The exchange of energy between components produces an increasing rate of entropy and creates a dynamical pressure term associated with the difference of temperature between components. This new dynamical pressure term fits with the results obtained by classical thermodynamical a...

  11. Effect of Mixture Pressure and Equivalence Ratio on Detonation Cell Size for Hydrogen-Air Mixtures

    Science.gov (United States)

    2015-06-01

    EFFECT OF MIXTURE PRESSURE AND EQUIVALENCE RATIO ON DETONATION CELL SIZE FOR HYDROGEN -AIR MIXTURES...protection in the United States. AFIT-ENY-MS-15-J-045 EFFECT OF MIXTURE PRESSURE AND EQUIVALENCE RATIO ON DETONATION CELL SIZE FOR HYDROGEN -AIR...DISTRIBUTION UNLIMITED. AFIT-ENY-MS-15-J-045 EFFECT OF MIXTURE PRESSURE AND EQUIVALENCE RATIO ON DETONATION CELL SIZE FOR HYDROGEN -AIR MIXTURES

  12. A numerical analysis of the effects of a stratified pre-mixture on homogeneous charge compression ignition combustion

    Energy Technology Data Exchange (ETDEWEB)

    Jamsran, Narankhuu; Lim, Ock Taeck [University of Ulsan, Ulsan (Korea, Republic of)

    2012-06-15

    We investigated the efficacy of fuel stratification in a pre-mixture of dimethyl ether (DME) and n-butane, which have different autoignition characteristics, for reducing the pressure rise rate (PRR) of homogeneous charge compression ignition engines. A new chemical reaction model was created by mixing DME and n-butane and compared with existing chemical reaction models to verify the effects observed. The maximum PRR depended on the mixture ratio. When DME was charged with stratification and n-butane was charged with homogeneity, the maximum PRR was the lowest among all the mixtures studied. Calculations were performed using CHEMKIN and modified using SENKIN software.

  13. Critical temperatures and pressures of reacting mixture in synthesis of dimethyl carbonate with methanol and carbon dioxide

    Institute of Scientific and Technical Information of China (English)

    Xing Cui Guo; Zhang Feng Qin; Guo Fu Wang; Jian Guo Wang

    2008-01-01

    Critical temperatures and pressures of nominal reacting mixture in synthesis of dimethyl carbonate (DMC)from methanol and carbon dioxide(quaternary mixture of carbon dioxide+methanol+water+DMC)were measured using a high-pressure view cell.The results suggested that the critical properties of the reacting mixture depended on the reaction extent as well as its initial composition(initial ratio of carbon dioxide to methanol).Such information is essential for determining the reaction conditions when one intends to carry out the synthesis of DMC with CO2 and methanol under supercritical conditions.

  14. Combustion synthesis of silicon carbide assisted by a magnesium plus polytetrafluoroethylene mixture

    Energy Technology Data Exchange (ETDEWEB)

    Ayral, R.M. [Institut Charles Gerhardt Montpellier, PMOF-UM2-CNRS Pl. E. Bataillon, 34095 Montpellier Cedex 5 (France); Rouessac, F., E-mail: florence.rouessac@univ-montp2.fr [Institut Charles Gerhardt Montpellier, PMOF-UM2-CNRS Pl. E. Bataillon, 34095 Montpellier Cedex 5 (France); Massoni, N. [CEA, DEN, DTCD, 30207 Bagnols-sur-Ceze (France)

    2009-11-15

    In this study, the use of SiC combustion synthesis for immobilization of {sup 14}C was considered. Due to the low exothermicity of the reaction between silicon and graphite, a highly exothermic mixture (magnesium and polytetrafluoroethylene) was used both as a chemical oven and activate additive in the mixture. With this configuration the reaction between graphite and silicon was initiated and propagated on the whole sample. The self-propagating high temperature synthesis samples were characterized by using scanning electron microscopy and X-ray diffraction.

  15. Heterogeneous Catalysis: Deuterium Exchange Reactions of Hydrogen and Methane

    Science.gov (United States)

    Mirich, Anne; Miller, Trisha Hoette; Klotz, Elsbeth; Mattson, Bruce

    2015-01-01

    Two gas phase deuterium/hydrogen exchange reactions are described utilizing a simple inexpensive glass catalyst tube containing 0.5% Pd on alumina through which gas mixtures can be passed and products collected for analysis. The first of these exchange reactions involves H[subscript 2] + D[subscript 2], which proceeds at temperatures as low as 77…

  16. Shock-Induced Chemical Reactions in Structural Energetic Materials

    Science.gov (United States)

    Narayanan, V.; Lu, X.; Hanagud, S.

    2006-07-01

    Various powder mixtures like intermetallic mixtures and mixtures of metals and metal oxides have potential applications as structural energetic materials (SEMs). Technologies of varying the compositions and the powder sizes and their synthesis are being investigated to provide multiple desirable characteristics, like high strength and high energy content. In this paper, we formulate a model for SEMs for their application in shock conditions, in the framework of nonequilibrium thermodynamics and continuum mechanics. A mixture of Al and KClO4 is selected as the example for SEMs. A mixture, pore collapse and chemical reaction model are included. By adapting energy barriers for reaction as a function of temperature, particle size and pressure and introducing a relaxation mechanism in the reaction model, a shock-induced chemical reaction model is developed. The variation of the relaxation mechanism is also modeled. The initiation and propagation of chemical reactions are studied. The time and spatial dependency of chemical reaction on the shock wave conditions are investigated.

  17. Hard-sphere kinetic models for inert and reactive mixtures

    Science.gov (United States)

    Polewczak, Jacek

    2016-10-01

    I consider stochastic variants of a simple reacting sphere (SRS) kinetic model (Xystris and Dahler 1978 J. Chem. Phys. 68 387-401, Qin and Dahler 1995 J. Chem. Phys. 103 725-50, Dahler and Qin 2003 J. Chem. Phys. 118 8396-404) for dense reacting mixtures. In contrast to the line-of-center models of chemical reactive models, in the SRS kinetic model, the microscopic reversibility (detailed balance) can be easily shown to be satisfied, and thus all mathematical aspects of the model can be fully justified. In the SRS model, the molecules behave as if they were single mass points with two internal states. Collisions may alter the internal states of the molecules, and this occurs when the kinetic energy associated with the reactive motion exceeds the activation energy. Reactive and non-reactive collision events are considered to be hard sphere-like. I consider a four component mixture A, B, A *, B *, in which the chemical reactions are of the type A+B\\rightleftharpoons {{A}\\ast}+{{B}\\ast} , with A * and B * being distinct species from A and B. This work extends the joined works with George Stell to the kinetic models of dense inert and reactive mixtures. The idea of introducing smearing-type effect in the collisional process results in a new class of stochastic kinetic models for both inert and reactive mixtures. In this paper the important new mathematical properties of such systems of kinetic equations are proven. The new results for stochastic revised Enskog system for inert mixtures are also provided.

  18. Role of mixing processes in the burning of pyrotechnics mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Bakhman, N.N. [Institute of Chemical Physics, Academy of Sciences, Moscow (Russian Federation)

    1996-12-31

    The burning velocity, u, of pyrotechnics mixtures and the dependence u(d) (where d is particles size of components of mixtures) is affected significantly by the mixing rate of oxidizer and fuel in the combustion wave. The rate of mixing depends strongly on the aggregate state of components in the preheat and reaction zone (P- and R-zone). If the molecular diffusion is the only mechanism of mixing, the mass transfer rate is proportional to {rho}D (where {rho} and D is density and diffusion coefficient). The experiments carried out in this paper show that u(d) dependence is very strong for non-volatile components for which the value {rho}D is small enough. Thus, for KCIO{sub 4}-W mixtures u augments 20-50 times with d{sub w} decreasing from 340 to {approx}3 {mu}m. In contrast, for components which can readily gasify in the P- and R-zone the value {rho}D is high enough and the dependence u(d) is faint. Thus, for AP -PMMA and AP-PS mixtures the burning rate augments not more than twice with d{sub AP} decreasing from 240 to {approx}9 {mu}m (and for stoichiometric Ba(NO{sub 3}){sub 2} AP-AI mixture u increases 3-.5 times with d{sub Bat(NO{sub 3})2} decreasing from 820 to {approx}10 {mu}m). If oxidizer and fuel remain solid in the P- and R-zone the burning rate may be increased with the addition of substances capable to transport one of the components through the gas phase to the surface of particles of the second component. Possible role of turbulent diffusion and convective transfer of a component in the combustion zone are discussed. (author) 11 refs.

  19. Ignition by Hot Transient Jets in Confined Mixtures of Gaseous Fuels and Air

    Directory of Open Access Journals (Sweden)

    Abdullah Karimi

    2016-01-01

    Full Text Available Ignition of a combustible mixture by a transient jet of hot reactive gas is important for safety of mines, prechamber ignition in IC engines, detonation initiation, and novel constant-volume combustors. The present work is a numerical study of the hot jet ignition process in a long constant-volume combustor (CVC that represents a wave rotor channel. The hot jet of combustion products from a prechamber is injected through a converging nozzle into the main CVC chamber containing a premixed fuel-air mixture. Combustion in a two-dimensional analogue of the CVC chamber is modeled using a global reaction mechanism, a skeletal mechanism, or a detailed reaction mechanism for three hydrocarbon fuels: methane, propane, and ethylene. Turbulence is modeled using the two-equation SST k-ω model, and each reaction rate is limited by the local turbulent mixing timescale. Hybrid turbulent-kinetic schemes using some skeletal reaction mechanisms and detailed mechanisms are good predictors of the experimental data. Shock wave traverse of the reaction zone is seen to significantly increase the overall reaction rate, likely due to compression heating, as well as baroclinic vorticity generation that stirs and mixes reactants and increases flame area. Less easily ignitable methane mixture is found to show slower initial reaction and greater dependence on shock interaction than propane and ethylene.

  20. Transesterification of waste vegetable oil under pulse sonication using ethanol, methanol and ethanol-methanol mixtures.

    Science.gov (United States)

    Martinez-Guerra, Edith; Gude, Veera Gnaneswar

    2014-12-01

    This study reports on the effects of direct pulse sonication and the type of alcohol (methanol and ethanol) on the transesterification reaction of waste vegetable oil without any external heating or mechanical mixing. Biodiesel yields and optimum process conditions for the transesterification reaction involving ethanol, methanol, and ethanol-methanol mixtures were evaluated. The effects of ultrasonic power densities (by varying sample volumes), power output rates (in W), and ultrasonic intensities (by varying the reactor size) were studied for transesterification reaction with ethanol, methanol and ethanol-methanol (50%-50%) mixtures. The optimum process conditions for ethanol or methanol based transesterification reaction of waste vegetable oil were determined as: 9:1 alcohol to oil ratio, 1% wt. catalyst amount, 1-2 min reaction time at a power output rate between 75 and 150 W. It was shown that the transesterification reactions using ethanol-methanol mixtures resulted in biodiesel yields as high as >99% at lower power density and ultrasound intensity when compared to ethanol or methanol based transesterification reactions.

  1. Spallation reactions; Reactions de spallation

    Energy Technology Data Exchange (ETDEWEB)

    Cugon, J.

    1996-12-31

    Spallation reactions dominate the interactions of hadrons with nuclei in the GeV range (from {approx} 0.1 to {approx} 10 GeV). They correspond to a sometimes important ejection of light particles leaving most of the time a residue of mass commensurate with the target mass. The main features of the experimental data are briefly reviewed. The most successful theoretical model, namely the intranuclear cascade + evaporation model, is presented. Its physical content, results and possible improvements are critically discussed. Alternative approaches are shortly reviewed. (author). 84 refs.

  2. Thermal reactions of brushite cements.

    Science.gov (United States)

    Bohner, M; Gbureck, U

    2008-02-01

    The thermal reactions of a brushite cement made of beta-tricalcium phosphate (beta-TCP), monocalcium phosphate monohydrate (MCPM), and an aqueous solution were followed in situ with an isothermal calorimeter at 37 degrees C. The investigated parameters were the beta-TCP/MCPM weight ratio, the liquid-to-powder ratio, the synthesis route and milling duration of the beta-TCP powder, as well as the presence of sulfate, citrate, and pyrophosphate ions in the mixing liquid. The thermograms were complex, particularly for mixtures containing an excess of MCPM or additives in the mixing solution. Results suggested that the endothermic MCPM dissolution and the highly exothermic beta-TCP dissolution occurred simultaneously, thereby leading to the formation of a large exothermic peak at early reaction time. Both reactions were followed by the exothermic crystallization of brushite and in the presence of an excess of MCPM by the endothermic crystallization of monetite. Additives generally widened the main exothermic reaction peak, or in some cases with pyrophosphate ions postponed the main exothermic peak at late reaction time. Generally, the results could be well explained and understood based on thermodynamic and solubility data.

  3. Afrikaner spirituality: A complex mixture

    Directory of Open Access Journals (Sweden)

    Erna Olivier

    2006-10-01

    Full Text Available The article argues that the perception that Afrikaner spirituality is and has always been founded mainly or only upon the Calvinistic tradition is a misconception. Nineteenth century Afrikaner spiritualism consisted of a mixture of theology, philosophy and a way of adapting to extreme living conditions. These factors, although with different contents, are also the determinant issues that made 21st century Afrikaner spirituality such a complex phenomenon. The article postulates that the Afrikaner nation’s current identity crisis can be resolved by closely looking at the different influences on the spirituality of the nation and by carefully guiding the people through the complex set of multiple choices to a fresh relation with Christ in a new found Christian identity to confirm our Christian foundation.

  4. Kinetics Studies of the Reaction of Co(bpb) with the Azide Ion in Binary Methanol-Water Mixtures%甲醇-水二元混合物中Co(bpb)与叠氮离子反应的动力学研究

    Institute of Scientific and Technical Information of China (English)

    HASHEMI Javad; ALIZADEH Naader; MEGHDADI Soraia; AMIRNASR Mehdi

    2009-01-01

    Co(bpb)[bpbH2 is N,N'-o-phenylenebis(pyridine-2-carboxamide),C18H12N4O2] complex has active axial sites like a porphyrin complex.We studied the coordination of azide ion (N3-) to Co(bpb) in binary methanol-water mixtures by spectropbotometric method at the temperature range of 283-303 K.From the temperature dependence of the rate constant,activation parameters (Ea,△H#,△S#,and △G# were obtained.An isokinetic temperature at about 302 K was observed at which the formation rate of Co(bpb)-N3- was more or less independent of the solvent composition.The resulting △H against TAS plot showed a good linear correlation,indicating the existence of enthalpy-entropy compensation in azide complexation process.Under optimum conditions and based on the absorbance of Co(bpb)-N3- produced through complex formation,a spectrophotometric method for the determination of N3- in solution was developed.A linear relationship between the absorbance and N3- concentration was obtained in the range of (0.85-5.00)× was applied to the determination of N3- anion in real water samples.Key Words: Spectrophotometric;Kinetics;Binary mixture;Azide determination;Water sample

  5. Bayesian mixture models for spectral density estimation

    OpenAIRE

    Cadonna, Annalisa

    2017-01-01

    We introduce a novel Bayesian modeling approach to spectral density estimation for multiple time series. Considering first the case of non-stationary timeseries, the log-periodogram of each series is modeled as a mixture of Gaussiandistributions with frequency-dependent weights and mean functions. The implied model for the log-spectral density is a mixture of linear mean functionswith frequency-dependent weights. The mixture weights are built throughsuccessive differences of a logit-normal di...

  6. Thermodynamic Calculations for Complex Chemical Mixtures

    Science.gov (United States)

    Mcbride, B. J.

    1986-01-01

    General computer program, CECTRP, developed for calculation of thermodynamic properties of complex mixtures with option to calculate transport properties of these mixtures. Free-energy minimization technique used in equilibrium calculation. Rigorous equations used in transport calculations. Program calculates equilibrium compositions and corresponding thermodynamic and transport properties of mixtures. CECTRP accommodates up to 24 reactants, 20 elements, and 600 products, 400 of which are condensed. Written in FORTRAN IV for any large computer system.

  7. Shear viscosity of liquid mixtures Mass dependence

    CERN Document Server

    Kaushal, R

    2002-01-01

    Expressions for zeroth, second, and fourth sum rules of transverse stress autocorrelation function of two component fluid have been derived. These sum rules and Mori's memory function formalism have been used to study shear viscosity of Ar-Kr and isotopic mixtures. It has been found that theoretical result is in good agreement with the computer simulation result for the Ar-Kr mixture. The mass dependence of shear viscosity for different mole fraction shows that deviation from ideal linear model comes even from mass difference in two species of fluid mixture. At higher mass ratio shear viscosity of mixture is not explained by any of the emperical model.

  8. Empirical profile mixture models for phylogenetic reconstruction

    National Research Council Canada - National Science Library

    Si Quang, Le; Gascuel, Olivier; Lartillot, Nicolas

    2008-01-01

    Motivation: Previous studies have shown that accounting for site-specific amino acid replacement patterns using mixtures of stationary probability profiles offers a promising approach for improving...

  9. Overcoming the fundamental limit: combustion of a hydrogen-oxygen mixture in micro- and nano-bubbles

    NARCIS (Netherlands)

    Svetovoy, Vitaly; Postnikov, Alexander; Uvarov, Ilia; Sanders, Remco G.P.; Krijnen, Gijsbertus J.M.

    2016-01-01

    Combustion reactions quench in small volumes due to fast heat escape via the volume boundary. Nevertheless, the reaction between hydrogen and oxygen was observed in nano- and micro-bubbles. The bubbles containing a mixture of gases were produced in microsystems using electrochemical decomposition of

  10. Laser flash-photolysis and gas discharge in N2O-containing mixture: kinetic mechanism

    Science.gov (United States)

    Kosarev, Ilya; Popov, Nikolay; Starikovskaia, Svetlana; Starikovskiy, Andrey; mipt Team

    2011-10-01

    The paper is devoted to further experimental and theoretical analysis of ignition by ArF laser flash-photolysis and nanosecond discharge in N2O-containing mixture has been done. Additional experiments have been made to assure that laser emission is distributed uniformly throughout the cross-section. The series of experiments was proposed and carried out to check validity of O(1D) determination in experiments on plasma assisted ignition initiated by flash-photolysis. In these experiments, ozone density in the given mixture (mixture composition and kinetics has been preliminary analyzed) was measured using UV light absorption in Hartley band. Good coincidence between experimental data and results of calculations have been obtained Temporal behavior of energy input, electric field and electric current has been measured and analyzed. These data are considered as initial conditions for numerical modeling of the discharge in O2:N2O:H2:Ar = 0.3:1:3:5 mixture. Ion-molecular reactions and reactions of active species production in Ar:H2:O2:N2O mixture were analyzed. The set of reactions to describe chemical transformation in the system due to the discharge action has been selected.

  11. Simulation of mixture microstructures via particle packing models and their direct comparison with real mixtures

    Science.gov (United States)

    Gulliver, Eric A.

    The objective of this thesis to identify and develop techniques providing direct comparison between simulated and real packed particle mixture microstructures containing submicron-sized particles. This entailed devising techniques for simulating powder mixtures, producing real mixtures with known powder characteristics, sectioning real mixtures, interrogating mixture cross-sections, evaluating and quantifying the mixture interrogation process and for comparing interrogation results between mixtures. A drop and roll-type particle-packing model was used to generate simulations of random mixtures. The simulated mixtures were then evaluated to establish that they were not segregated and free from gross defects. A powder processing protocol was established to provide real mixtures for direct comparison and for use in evaluating the simulation. The powder processing protocol was designed to minimize differences between measured particle size distributions and the particle size distributions in the mixture. A sectioning technique was developed that was capable of producing distortion free cross-sections of fine scale particulate mixtures. Tessellation analysis was used to interrogate mixture cross sections and statistical quality control charts were used to evaluate different types of tessellation analysis and to establish the importance of differences between simulated and real mixtures. The particle-packing program generated crescent shaped pores below large particles but realistic looking mixture microstructures otherwise. Focused ion beam milling was the only technique capable of sectioning particle compacts in a manner suitable for stereological analysis. Johnson-Mehl and Voronoi tessellation of the same cross-sections produced tessellation tiles with different the-area populations. Control charts analysis showed Johnson-Mehl tessellation measurements are superior to Voronoi tessellation measurements for detecting variations in mixture microstructure, such as altered

  12. Thermodynamics of mixtures containing amines

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, Juan Antonio [G.E.T.E.F. Dpto Termodinamica y Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, Valladolid 47071 (Spain)], E-mail: jagl@termo.uva.es; Mozo, Ismael; Garcia de la Fuente, Isaias; Cobos, Jose Carlos [G.E.T.E.F. Dpto Termodinamica y Fisica Aplicada, Facultad de Ciencias, Universidad de Valladolid, Valladolid 47071 (Spain); Riesco, Nicolas [Department of Chemical Engineering, Loughborough University, Loughborough, LE113TU Leicestershire (United Kingdom)

    2008-01-30

    Mixtures with dimethyl or trimethylpyridines and alkane, aromatic compound or 1-alkanol have been examined using different theories: DISQUAC, Flory, the concentration-concentration structure factor, S{sub CC}(0), or the Kirkwood-Buff formalism. DISQUAC represents fairly well the available experimental data, and improves theoretical calculations from Dortmund UNIFAC. Two important effects have been investigated: (i) the effect of increasing the number of methyl groups attached to the aromatic ring of the amine; (ii) the effect of modifying the position of the methyl groups in this ring. The molar excess enthalpy, H{sup E}, and the molar excess volume, V{sup E}, decrease in systems with alkane or methanol as follows: pyridine > 3-methylpyridine > 3,5-dimethylpyridine and pyridine > 2-methylpyridine > 2,4-dimethylpyridine > 2,4,6-trimethylpyridine, which has been attributed to a weakening of the amine-amine interactions in the same sequences. This is in agreement with the relative variation of the effective dipole moment, {mu}-bar, and of the differences between the boiling temperature of a pyridine base and that of the homomorphic alkane. For heptane solutions, the observed H{sup E} variation, H{sup E} (3,5-dimethylpyridine) > H{sup E} (2,4-dimethylpyridine) > H{sup E} (2,6-dimethylpyridine), is explained similarly. Calculations on the basis of the Flory model confirm that orientational effects become weaker in systems with alkane in the order: pyridine > methylpyridine > dimethylpyridine > trimethylpyridine. S{sub CC}(0) calculations show that steric effects increase with the number of CH{sub 3}- groups in the pyridine base, and that the steric effects exerted by methyl groups in positions 2 and 6 are higher than when they are placed in positions 3 and 5. The hydrogen bond energy in methanol mixtures is independent of the pyridine base, and it is estimated to be -35.2 kJ mol{sup -1}. Heterocoordination in these solutions is due in part to size effects. Their

  13. Comparison of – Mixture and Minoxidil on Hair Growth Promoting Effect in Mice

    Directory of Open Access Journals (Sweden)

    Ki Soo Park

    2016-11-01

    Full Text Available BackgroundAlgae have traditionally been used for promotion of hair growth. Use of hair regrowth drugs, such as minoxidil, is limited due to side effects. The aim of this study was to examine a mixture of Saccharina japonica and Undaria pinnatifida (L-U mixture on hair growth and to compare the promoting effect of hair growth by a 3% minoxidil and a L-U mixture.MethodsTo evaluate the hair growth-promoting activity, saline, 50% ethanol, 3% minoxidil, and the L-U mixture were applied 2 times a day for a total of 14 days on the dorsal skin of C57BL/6 mice after depilation. Analysis was determined by using a high-resolution hair analysis system, real-time polymerase chain reaction, and H&E staining.ResultsOn day 14, the hair growth effect of the L-U mixture was the same as that of the 3% minoxidil treatment. The L-U mixture significantly (P<0.05 stimulated hair growth-promoting genes, as vascular endothelial growth factor (VEGF and insulin-like growth factor -1. Increase of VEGF was observed in the L-U mixture group compared with minoxidil and the negative control. In contrast, the L-U mixture suppressed the expression of transforming growth factor-β1, which is the hair loss-related gene. In histological examination in the L-U mixture and minoxidil groups, the induction of an anagen stage of hair follicles was faster than that of control groups.ConclusionsThis study provides evidence that the L-U mixture can promote hair growth in mice, similar to the effect from minoxidil, and suggests that there is potential application for hair loss treatments.

  14. Time-dependence in mixture toxicity prediction.

    Science.gov (United States)

    Dawson, Douglas A; Allen, Erin M G; Allen, Joshua L; Baumann, Hannah J; Bensinger, Heather M; Genco, Nicole; Guinn, Daphne; Hull, Michael W; Il'Giovine, Zachary J; Kaminski, Chelsea M; Peyton, Jennifer R; Schultz, T Wayne; Pöch, Gerald

    2014-12-04

    The value of time-dependent toxicity (TDT) data in predicting mixture toxicity was examined. Single chemical (A and B) and mixture (A+B) toxicity tests using Microtox(®) were conducted with inhibition of bioluminescence (Vibrio fischeri) being quantified after 15, 30 and 45-min of exposure. Single chemical and mixture tests for 25 sham (A1:A2) and 125 true (A:B) combinations had a minimum of seven duplicated concentrations with a duplicated control treatment for each test. Concentration/response (x/y) data were fitted to sigmoid curves using the five-parameter logistic minus one parameter (5PL-1P) function, from which slope, EC25, EC50, EC75, asymmetry, maximum effect, and r(2) values were obtained for each chemical and mixture at each exposure duration. Toxicity data were used to calculate percentage-based TDT values for each individual chemical and mixture of each combination. Predicted TDT values for each mixture were calculated by averaging the TDT values of the individual components and regressed against the observed TDT values obtained in testing, resulting in strong correlations for both sham (r(2)=0.989, n=25) and true mixtures (r(2)=0.944, n=125). Additionally, regression analyses confirmed that observed mixture TDT values calculated for the 50% effect level were somewhat better correlated with predicted mixture TDT values than at the 25 and 75% effect levels. Single chemical and mixture TDT values were classified into five levels in order to discern trends. The results suggested that the ability to predict mixture TDT by averaging the TDT of the single agents was modestly reduced when one agent of the combination had a positive TDT value and the other had a minimal or negative TDT value. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  15. Fuel properties of bituminous coal and pyrolytic oil mixture

    Science.gov (United States)

    Hamdan, Hazlin; Sharuddin, Munawar Zaman; Daud, Ahmad Rafizan Mohamad; Syed-Hassan, Syed Shatir A.

    2014-10-01

    Investigation on the thermal decomposition kinetics of coal-biooil slurry (CBS) fuel prepared at different ratios (100:0,70:30,60:40,0:100) was conducted using a Thermogravimetric Analyzer (TGA). The materials consisted of Clermont bituminous coal (Australia) and bio-oil (also known as pyrolytic oil) from the source of Empty Fruit Bunch (EFB) that was thermally converted by means of pyrolysis. Thermal decomposition of CBS fuel was performed in an inert atmosphere (50mL/min nitrogen) under non-isothermal conditions from room temperature to 1000°C at heating rate of 10°C/min. The apparent activation energy (Ea.) and pre-exponential factor (A) were calculated from the experimental results by using an Arrhenius-type kinetic model which first-order decomposition reaction was assumed. All kinetic parameters were tabulated based on the TG data obtained from the experiment. It was found that, the CBS fuel has higher reactivity than Clermont coal fuel during pyrolysis process, as the addition of pyrolytic oil will reduce the Ea values of the fuel. The thermal profiles of the mixtures showed potential trends that followed the characteristics of an ideal slurry fuel where high degradation rate is desirable. Among the mixture, the optimum fuel was found at the ratio of 60:40 of pyrolytic oil/coal mixtures with highest degradation rate. These findings may contribute to the development of a slurry fuel to be used in the vast existing conventional power plants.

  16. Pulsed microwave discharges in powder mixtures: Status, problems, and prospects

    Science.gov (United States)

    Batanov, G. M.; Kossyi, I. A.

    2015-10-01

    Results of experiments on the excitation of pulsed microwave discharges by gyrotron radiation (λ = 4 mm, P 0 = 100-500 kW, τ = 1-10 ms) in the volumes and on the surfaces of metal-dielectric powder mixtures are presented. It is shown that there are two phases of discharge development: the spark phase, accompanied by a partial evaporation of the powder material, and the phase of a developed discharge, characterized by a plasma density of ˜1017 cm-3, high absorption, and high temperatures (˜5-10 kK) in a thin layer (˜0.1-0.2 mm) of plasma and vapor. It is demonstrated that the conductivity induced in the targets by UV radiation play an important role in the microwave absorption by powder grains. It is found that, in the course of the discharge, a conductive metal mesh forms in the powder volume as a result of metal evaporation. Reactions of high-temperature synthesis were initiated in various powder mixtures (Ti + B, Al + Fe2O3, Mo + B, etc.). It is shown that the reactions of high-temperature synthesis last for up to 0.1 s and are accompanied by the evaporation of powder grains and the formation of an aerosol cloud due to free expansion of reactants from the sample surface. The possibility of experimentally studying the kinetics of reactions of high-temperature synthesis is demonstrated. It is noticed that microwave discharges can be used to initiate plasmachemical reactions on the surfaces of radioparent materials in active gaseous media.

  17. Calculations of phase equilibria for mixtures of triglycerides, fatty acids, and their esters in lower alcohols

    Science.gov (United States)

    Stepanov, D. A.; Ermakova, A.; Anikeev, V. I.

    2011-01-01

    The objects of study were mixtures containing triglycerides and lower alcohols and also the products of the transesterification of triglycerides, glycerol and fatty acid esters. The Redlich-Kwong-Soave equation of state was used as a thermodynamic model for the phase state of the selected mixtures over wide temperature, pressure, and composition ranges. Group methods were applied to determine the critical parameters of pure substances and their acentric factors. The parameters obtained were used to calculate the phase diagrams and critical parameters of mixtures containing triglycerides and lower alcohols and the products of the transesterification of triglycerides, glycerol and fatty acid esters, at various alcohol/oil ratios. The conditions of triglyceride transesterification in various lower alcohols providing the supercritical state of reaction mixtures were selected.

  18. Solvatochromic and Kinetic Response Models in (Ethyl Acetate + Chloroform or Methanol Solvent Mixtures

    Directory of Open Access Journals (Sweden)

    L. R. Vottero

    2000-03-01

    Full Text Available The present work analyzes the solvent effects upon the solvatochromic response models for a set of chemical probes and the kinetic response models for an aromatic nucleophilic substitution reaction, in binary mixtures in which both pure components are able to form intersolvent complexes by hydrogen bonding.

  19. The decrease in the IgG-binding capacity of intensively dry heated whey proteins is associatead with intense Maillard reaction, structural changes of the proteins and formation of RAGE-ligands

    NARCIS (Netherlands)

    Liu, F.; Teodorowicz, M.; Boekel, van M.A.J.S.; Wichers, H.J.; Hettinga, K.A.

    2016-01-01

    Heat treatment is the most common way of milk processing, inducing structural changes as well as chemical modifications in milk proteins. These modifications influence the immune-reactivity and allergenicity of milk proteins. This study shows the influence of dry heating on the solubility, particle

  20. 美拉德反应对醋蛋多肽抗氧化活性的影响%Effect of Maillard Reaction on Antioxidant Activity of Peptides from Vinegar Eggs

    Institute of Scientific and Technical Information of China (English)

    杨锋; 陈锦屏; 林心怡

    2013-01-01

    采用醋蛋多肽与葡萄糖发生美拉德反应来改善醋蛋多肽的抗氧化活性.结果表明:优化的美拉德反应条件为醋蛋多肽与葡萄糖质量比1:2、反应初始pH10、反应温度100℃、反应时间120min.在此反应条件下,反应产物的抗氧化活性与未反应的醋蛋多肽相比,DPPH自由基清除率从12.7%增加到64.8%,Fe3+还原能力(A700nm)从0.107增加到0.718.在此反应过程中,反应产物的抗氧化活性随着反应体系pH值降低、中间产物(A294nm)和褐变程度(A420nm)以及接枝度的增加而不断增强.

  1. Mixture Modeling: Applications in Educational Psychology

    Science.gov (United States)

    Harring, Jeffrey R.; Hodis, Flaviu A.

    2016-01-01

    Model-based clustering methods, commonly referred to as finite mixture modeling, have been applied to a wide variety of cross-sectional and longitudinal data to account for heterogeneity in population characteristics. In this article, we elucidate 2 such approaches: growth mixture modeling and latent profile analysis. Both techniques are…

  2. Two-microphone Separation of Speech Mixtures

    DEFF Research Database (Denmark)

    2006-01-01

    Matlab source code for underdetermined separation of instaneous speech mixtures. The algorithm is described in [1] Michael Syskind Pedersen, DeLiang Wang, Jan Larsen and Ulrik Kjems: ''Two-microphone Separation of Speech Mixtures,'' 2006, submitted for journal publoication. See also, [2] Michael...

  3. Fibril assembly in whey protein mixtures

    NARCIS (Netherlands)

    Bolder, S.G.

    2007-01-01

    The objective of this thesis was to study fibril assembly in mixtures of whey proteins. The effect of the composition of the protein mixture on the structures and the resulting phase behaviour was investigated. The current work has shown that beta-lactoglobulin is responsible for the fibril assembly

  4. Excited state charge transfer reaction in (mixed solvent + electrolyte) systems: Role of reactant-solvent and reactant-ion interactions

    Indian Academy of Sciences (India)

    Harun Al Rasid Gazi; Ranjit Biswas

    2011-05-01

    Fluorescence spectroscopic techniques have been used to study the excited state intramolecular charge transfer reaction of 4-(1-azetidinyl)benzonitrile (P4C) in two sets of mixed solvents, (1-propanol + ethyl acetate) and (propylene carbonate + acetonitrile), in the absence and presence of a strong electrolyte, lithium perchlorate. These two sets of mixed solvent systems represent binary solvent mixtures of low and high polarities, respectively. Density, sound velocity and viscosity measurements indicate that these two mixed solvent systems are structurally different. Stronger ion-reactant interaction is evidenced in the mole fraction independence of emission frequencies in electrolyte solutions of low polar binary solvent mixtures. For both these mixtures, the reaction driving force (- ) decreases with increase in mole fraction of the relatively less polar solvent component of the mixture. Interestingly, - increases significantly on addition of electrolyte in low polar mixtures and exhibits mixture composition dependence but, in contrast, - in high polar mixtures does not sense variation in mixture composition in presence of electrolyte. This insensitivity to mixture composition for high polar mixtures is also observed for the measured reaction time constant. In addition, the reaction time constant does not sense the presence of electrolyte in the high polar solvent mixtures. The reaction time constant in low polar mixtures, which becomes faster on addition of electrolyte, lengthens on increasing the mole fraction of the relatively less polar solvent component of the mixture. These observations have been qualitatively explained in terms of the measured solvent reorganization energy and reaction driving force by using expressions from the classical theory of electron transfer reaction.

  5. Intensification of the electro slag process exothermic mixtures (fluxеs

    Directory of Open Access Journals (Sweden)

    А. Ф. Власов

    2015-03-01

    Full Text Available It is established that an effective way to improve performance is to use the electro slag processes exothermic mixture (mechanical mixture scaling of aluminum powder and а standard flux or flux exothermic (mechanical scaling mixtures, alloys, aluminum powder and a flux standard in amounts sufficient for the exothermal reaction. Experimentally is defined the presence of the electrically conductive layer exothermic flux, allowing to carry out the electro slag process mono, bifilar or three-phase circuit using a "solid" start. The influence of the exothermic metal-flux mixtures to hold electro slag processes. Submitted exothermic flux composition consisting of a mixture of dross and aluminum powder, the alloying additives are calculations of thermal effects, and the optimal ratios and electrode coating formulation with the exothermic mixture. The results of investigation of influence of particle size distribution of ferroalloys on solubility in reducing metal when the exothermic reaction and the chemical composition of electro-metal. The dependence of the electro-chemical composition of the metal particle size distribution of ferroalloys and method of melting exothermic flux. The optimum particle size. When the exothermic process and the mixture of aluminum dross occurs to change the chemical composition of the slag at the expense of additional content of aluminum oxide formed, but it does not reduce the ability of fluoride desulfurizing flux used in the electro slag processes. The results of studies of formation of the metal structure using ekzosmesi content of nonmetallic inclusions. The results of technical and economic parameters ways start ESR. It is proved that the use of exothermic alloyed flux does not affect the quality of melted metal. The use of exothermic alloyed flux allows more efficient use flux melting furnace and put them in the manufacture of parts for various purposes. Introduction exothermic mixture or exothermic flux can

  6. Supercritical separation process for complex organic mixtures

    Science.gov (United States)

    Chum, Helena L.; Filardo, Giuseppe

    1990-01-01

    A process is disclosed for separating low molecular weight components from complex aqueous organic mixtures. The process includes preparing a separation solution of supercritical carbon dioxide with an effective amount of an entrainer to modify the solvation power of the supercritical carbon dioxide and extract preselected low molecular weight components. The separation solution is maintained at a temperature of at least about 70.degree. C. and a pressure of at least about 1,500 psi. The separation solution is then contacted with the organic mixtures while maintaining the temperature and pressure as above until the mixtures and solution reach equilibrium to extract the preselected low molecular weight components from the organic mixtures. Finally, the entrainer/extracted components portion of the equilibrium mixture is isolated from the separation solution.

  7. Designing of Synergistic Waste Mixtures for Multiphase Reactive Smelting

    Directory of Open Access Journals (Sweden)

    Vaso Manojlović

    2016-06-01

    Full Text Available Electric arc furnace (EAF dust, together with a mill scale and coke were smelted in a laboratory electric arc furnace. These metallurgical wastes consist of a many different phases and elements, making the reaction process complex. Thermo-chemical analysis of the reactions in metal, slag, and gas phases was done, and used for modeling of the mixture composition and energy consumption required for smelting. Modelling was performed with the software named RikiAlC. The crude ZnO, slag, and metal phase were analyzed using the atomic absorption spectrometry (AAS, the optical emission spectrometry with inductively coupled plasma (ICP-OES, the X-ray diffraction (XRD, the scanning electron microscopy (SEM equipped with energy dispersive spectrometry (EDS, and reflected and transmitted light microscopy. Also, in order to follow the behavior of this process the exhausted gases were monitored. The synergetic effects of the designed mixture may be recognized in minimizing energy consumption for the smelting process, improving the product yield efficiency, and reducing the negative environmental effects.

  8. Determination of peracetic acid and hydrogen peroxide in the mixture

    Directory of Open Access Journals (Sweden)

    Bodiroga Milanka

    2002-01-01

    Full Text Available Iodometric and permanganometric titrations were used for determination of peracetic acid and hydrogen peroxide (H2O2 in the mixture. Two procedures were described and compared. Titrations could be done in only one vessel, in the same reaction mixture, when iodometric titration of peracetic acid was continued after the permanganometric titration of H2O2, (procedure A. Peracetic acid and H2O2, as oxidizing agents, reacted with potassium iodide in an acid medium, evolving iodine. This reaction was used for the quantitative iodometric determination of total peroxide in procedure B. H2O2 reacted with potassium permanganate in acid medium, but peracetic acid did not react under the same conditions. That made possible the selective permanganometric determination of H2O2 in the presence of peracetic acid. The procedure B was performed in two titration vessels (KV=3.4% for peracetic acid, 0.6% for H2O2. The procedure A for iodometric determination of peracetic acid in one titration vessel after permanganometric titration of H2O2 was recommended (KV=2,5% for peracetic acid, 0,45% for H2O2.

  9. Water-CO2 Mixtures Under Extreme Conditions

    Science.gov (United States)

    Plattner, D. L.; Somayazulu, M.

    2010-12-01

    In situ high pressure-temperature Raman spectroscopy was used to investigate the formation of clathrates in water-CO2 mixtures and to study the chemical interactions between water and CO2 at supercritical conditions. Diamond anvil cell’s (DAC) were loaded with ruby, water, CO2, and a gold plated gasket. Quartz was later added to the cell as a pressure sensor for supercritical phase analysis. At 25 °C and within the pressure range of 0.8 to 2.6 GPa, no clathrate was observed. Our results confirm recent findings which also dispute claims of clathrate existence at our conditions. A decrease in the temperature required to reach the supercritical phase of water-CO2 mixtures was observed from 0.35 GPa to 4.5 GPa. Furthermore, at 4.4 GPa and 290 °C, a chemical reaction between CO2 and water occurred. The resulting compound has a Raman peak with a frequency shift of 1000 cm-1. This reaction and the compound it produces are of great interest and are currently being investigated.

  10. Studying barrier-discharge-stimulated plasmachemical reactions

    Science.gov (United States)

    Malanichev, V. E.; Malashin, M. V.; Moshkunov, S. I.; Nebogatkin, S. V.; Khomich, V. Yu.; Shmelev, V. M.

    2017-05-01

    Barrier-discharge stimulation of chemical reactions has been studied in the case of methane oxidation by atmospheric oxygen with the formation of carbon monoxide and hydrogen. Experiments in a plasmachemical reactor demonstrated the possibility of increasing the yield of synthesis gas (syngas) by means of plasma pretreatment of the initial mixture of air and methane in a 7: 1 ratio at atmospheric pressure. The output-gas composition was determined by gas chromatography. It is established that the plasma-discharge treatment of the initial gas mixture leads to a 15% increase in the amount of syngas at the reactor output and increases the reaction selectivity with respect to hydrogen and carbon monoxide by 3.2 and 6.5%, respectively.

  11. Effects of intake of heated mixtures of glucose-lysine and glucose-methionine on bone calcium

    OpenAIRE

    2005-01-01

    Durante el tratamiento térmico de los alimentos puede desarrollarse la reacción de Maillard, que tiene lugar, fundamentalmente, entre los grupos carbonilo de azúcares reductores y los grupo amino proteicos. Los productos de la reacción de Maillard (PRM) pueden afectar la biodisponibilidad mineral por modificaciones de su forma físico-química en el alimento o en el lumen, alterando el proceso de absorción o su normal metabolismo. En este trabajo se estudió la influencia de PRM sobre aspectos d...

  12. Nucleotide Selectivity in Abiotic RNA Polymerization Reactions

    Science.gov (United States)

    Coari, Kristin M.; Martin, Rebecca C.; Jain, Kopal; McGown, Linda B.

    2017-09-01

    In order to establish an RNA world on early Earth, the nucleotides must form polymers through chemical rather than biochemical reactions. The polymerization products must be long enough to perform catalytic functions, including self-replication, and to preserve genetic information. These functions depend not only on the length of the polymers, but also on their sequences. To date, studies of abiotic RNA polymerization generally have focused on routes to polymerization of a single nucleotide and lengths of the homopolymer products. Less work has been done the selectivity of the reaction toward incorporation of some nucleotides over others in nucleotide mixtures. Such information is an essential step toward understanding the chemical evolution of RNA. To address this question, in the present work RNA polymerization reactions were performed in the presence of montmorillonite clay catalyst. The nucleotides included the monophosphates of adenosine, cytosine, guanosine, uridine and inosine. Experiments included reactions of mixtures of an imidazole-activated nucleotide (ImpX) with one or more unactivated nucleotides (XMP), of two or more ImpX, and of XMP that were activated in situ in the polymerization reaction itself. The reaction products were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the lengths and nucleotide compositions of the polymerization products. The results show that the extent of polymerization, the degree of heteropolymerization vs. homopolymerization, and the composition of the polymeric products all vary among the different nucleotides and depend upon which nucleotides and how many different nucleotides are present in the mixture.

  13. Nucleotide Selectivity in Abiotic RNA Polymerization Reactions

    Science.gov (United States)

    Coari, Kristin M.; Martin, Rebecca C.; Jain, Kopal; McGown, Linda B.

    2017-02-01

    In order to establish an RNA world on early Earth, the nucleotides must form polymers through chemical rather than biochemical reactions. The polymerization products must be long enough to perform catalytic functions, including self-replication, and to preserve genetic information. These functions depend not only on the length of the polymers, but also on their sequences. To date, studies of abiotic RNA polymerization generally have focused on routes to polymerization of a single nucleotide and lengths of the homopolymer products. Less work has been done the selectivity of the reaction toward incorporation of some nucleotides over others in nucleotide mixtures. Such information is an essential step toward understanding the chemical evolution of RNA. To address this question, in the present work RNA polymerization reactions were performed in the presence of montmorillonite clay catalyst. The nucleotides included the monophosphates of adenosine, cytosine, guanosine, uridine and inosine. Experiments included reactions of mixtures of an imidazole-activated nucleotide (ImpX) with one or more unactivated nucleotides (XMP), of two or more ImpX, and of XMP that were activated in situ in the polymerization reaction itself. The reaction products were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify the lengths and nucleotide compositions of the polymerization products. The results show that the extent of polymerization, the degree of heteropolymerization vs. homopolymerization, and the composition of the polymeric products all vary among the different nucleotides and depend upon which nucleotides and how many different nucleotides are present in the mixture.

  14. The Reaction between Iron(II) Iodide and Potassium Dichromate(VI) in Acidified Aqueous Solution

    Science.gov (United States)

    Talbot, Christopher

    2013-01-01

    This "Science note" teaching lesson explores the possible reaction between the ions in a reaction mixture consisting of iron(II) iodide and potassium dichromate(VI) in acidified aqueous solution. The electrode potentials will be used to deduce any spontaneous reactions under standard thermodynamic conditions (298 K, 1 bar (approximately…

  15. The Reaction between Iron(II) Iodide and Potassium Dichromate(VI) in Acidified Aqueous Solution

    Science.gov (United States)

    Talbot, Christopher

    2013-01-01

    This "Science note" teaching lesson explores the possible reaction between the ions in a reaction mixture consisting of iron(II) iodide and potassium dichromate(VI) in acidified aqueous solution. The electrode potentials will be used to deduce any spontaneous reactions under standard thermodynamic conditions (298 K, 1 bar (approximately…

  16. On the mixture model for multiphase flow

    Energy Technology Data Exchange (ETDEWEB)

    Manninen, M.; Taivassalo, V. [VTT Energy, Espoo (Finland). Nuclear Energy; Kallio, S. [Aabo Akademi, Turku (Finland)

    1996-12-31

    Numerical flow simulation utilising a full multiphase model is impractical for a suspension possessing wide distributions in the particle size or density. Various approximations are usually made to simplify the computational task. In the simplest approach, the suspension is represented by a homogeneous single-phase system and the influence of the particles is taken into account in the values of the physical properties. This study concentrates on the derivation and closing of the model equations. The validity of the mixture model is also carefully analysed. Starting from the continuity and momentum equations written for each phase in a multiphase system, the field equations for the mixture are derived. The mixture equations largely resemble those for a single-phase flow but are represented in terms of the mixture density and velocity. The volume fraction for each dispersed phase is solved from a phase continuity equation. Various approaches applied in closing the mixture model equations are reviewed. An algebraic equation is derived for the velocity of a dispersed phase relative to the continuous phase. Simplifications made in calculating the relative velocity restrict the applicability of the mixture model to cases in which the particles reach the terminal velocity in a short time period compared to the characteristic time scale of the flow of the mixture. (75 refs.)

  17. Foaming of mixtures of pure hydrocarbons

    Science.gov (United States)

    Robinson, J. V.; Woods, W. W.

    1950-01-01

    Mixtures of pure liquid hydrocarbons are capable of foaming. Nine hydrocarbons were mixed in pairs, in all possible combinations, and four proportions of each combination. These mixtures were sealed in glass tubes, and the foaming was tested by shaking. Mixtures of aliphatic with other aliphatic hydrocarbons, or of alkyl benzenes with other alkyl benzenes, did not foam. Mixtures of aliphatic hydrocarbons with alkyl benzenes did foam. The proportions of the mixtures greatly affected the foaming, the maximum foaming of 12 of 20 pairs being at the composition 20 percent aliphatic hydrocarbon, 80 percent alkyl benzene. Six seconds was the maximum foam lifetime of any of these mixtures. Aeroshell 120 lubricating oil was fractionated into 52 fractions and a residue by extraction with acetone in a fractionating extractor. The index of refraction, foam lifetime, color, and viscosity of these fractions were measured. Low viscosity and high index fractions were extracted first. The viscosity of the fractions extracted rose and the index decreased as fractionation proceeded. Foam lifetimes and color were lowest in the middle fractions. Significance is attached to the observation that none of the foam lifetimes of the fractions or residue is as high as the foam lifetime of the original Aeroshell, indicating that the foaming is not due to a particular foaming constituent, but rather to the entire mixture.

  18. Catalytic Formation of Propylene Carbonate from Supercritical Carbon Dioxide/Propylene Oxide Mixture

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Propylene carbonate was synthesized from supercritical carbon dioxide (SC-CO2)/ propylene oxide mixture with phthalocyaninatoaluminium chloride (ClAlPc)/ tetrabutylammon-ium bromide (n-Bu4NBr) as catalyst. The high rate of reaction was attributed to rapid diffusion and the high miscibility of propylene oxide in SC-CO2 under employed conditions. Various reaction periods present different formation rate of propylene carbonate, mainly due to the existence of phase change during the reaction. The experimental results demonstrate that SC-CO2 could be used as not only an environmentally benign solvent but also a carbon precursor in synthesis.

  19. Kinetics of Zr-alloy cladding oxidation in the mixture of air and steam at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung Tae; Park, Kwang Heon; Park, Joo Young [Kyunghee University, Yongin (Korea, Republic of)

    2012-05-15

    In Fukushima Daiichi Nuclear Power Plant accident, No.4 plant was exploded by hydrogen explosion. There was a strong speculation about the possibility of the reaction between the overheated fuels and the steam-air mixture in the storage pool. Later, it turned out to be due to the hydrogen leaked from No.3 plant. However, the reaction of the hot fuels with the steam-air mixture became an important issue. There have been a lot of data accumulated about Zr-alloy interaction with steam. However, Zr-alloy interactions with air and steam-air mixtures have not been studied relatively much. In this study, we measured the oxidation kinetics of Zry-4 and Zirlo claddings in air, and steam-air mixtures, and analyzed the kinetics

  20. Coking technology using packed coal mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Kuznichenko, V.M.; Shteinberg, Eh.A.; Tolstoi, A.P. (Khar' kovskii Nauchno-Issledovatel' skii Uglekhimicheskii Institut, Kharkov (Ukrainian SSR))

    1991-08-01

    Discusses coking of packed coal charges in the FRG, USSR, France, India, Poland and Czechoslovakia. The following aspects are evaluated: types of weakly caking coals that are used as components of packed mixtures, energy consumption of packing, effects of coal mixture packing on coke oven design, number of coke ovens in a battery, heating temperature, coking time, coke properties, investment and operating cost. Statistical data that characterize the Saarberg packing process used in the FRG are analyzed. Packing coal mixtures for coking improves coke quality and reduces environmental pollution. 4 refs.

  1. Benchtop monitoring of reaction progress via visual recognition with a handheld UV lamp: in situ monitoring of boronic acids in the Suzuki-Miyaura reaction.

    Science.gov (United States)

    Barder, Timothy E; Buchwald, Stephen L

    2007-01-04

    [reaction: see text] Although boronic acids are widely used in metal-catalyzed reactions, it is difficult to assay their consumption. As such, we developed a reversible fluorescent sensor that is activated upon binding a boronic acid. The sensor can be used to monitor consumption of a boronic acid in Suzuki-Miyaura reactions. Importantly, only a standard handheld long-wave UV lamp (365 nm) is required and fluorescence is easily detectable with the naked eye without disturbing the reaction mixture.

  2. Holographic Superfluidity in Imbalanced Mixtures

    CERN Document Server

    Erdmenger, Johanna; Kerner, Patrick; Ngo, Thanh Hai

    2011-01-01

    We construct superfluid black hole solutions with two chemical potentials. By analogy with QCD, the two chemical potentials correspond to the baryon and isospin symmetries, respectively. We consider two systems: the back-reacted U(2) Einstein-Yang-Mills theory in 4+1 dimensions and the 9+1-dimensional D3/D7 brane setup with two coincident D7-brane probes. In the D7-brane model, the identification of baryon and isospin chemical potential is explicit since the dual field theory is explicitly known. Studying the phase diagram, we find in both systems a quantum phase transition at a critical ratio of the two chemical potentials. However the quantum phase transition is different in the two systems: In the D3/D7 brane setup we always find a second order phase transition, while in the Einstein-Yang-Mills theory, depending on the strength of the back-reaction, we obtain a continuous or first order transition. We expect the continuous quantum phase transition to be BKT-like. We comment on the origin of this differing ...

  3. Differentiation of rye and wheat flour as well as mixtures by using the kinetics of Karl Fischer water titration.

    Science.gov (United States)

    Hădărugă, Daniel I; Costescu, Corina I; Corpaş, Laura; Hădărugă, Nicoleta G; Isengard, Heinz-Dieter

    2016-03-15

    The aim of this study was to find a simple way to differentiate between rye and wheat flour and their mixtures by using the kinetic parameters of Karl Fischer water titration (KFT). Consequently, the water content and type of molecules in rye and wheat mixtures used in Romanian bread making have been investigated by means of volumetric KFT. Further, the kinetics of KFT have been determined and novel kinetic parameters corresponding to "surface" and "strongly-retained" water molecules have been identified to discriminate between rye and wheat flour and their mixtures. The "surface" and "strongly-retained" water reaction rates well correlate with the rye content in the flour mixtures, especially at higher temperature analysis (r>0.95). These parameters can be used as indicators for quality evaluation of such type of mixtures, as well as to identify adulteration by improper use of the rye-wheat flour ratios in bread making.

  4. Direct partial oxidation of methane to methanol: Reaction zones and role of catalyst location

    Institute of Scientific and Technical Information of China (English)

    Qijian Zhang; Dehua He; Qiming Zhu

    2008-01-01

    Direct partial oxidation of methane to methanol was investigated in a specially designed reactor. Methanol yield of about 7%-8% was obtained in gas phase partial oxidation. It was proposed that the reactor could be divided into three reaction zones, namely pre-reaction zone, fierce reaction zone, and post-reaction zone, when the temperature was high enough to initiate a reaction. The oxidation of methane proceeded and was completed mostly in the fierce reaction zone. When the reactant mixture entered the post-reaction zone, only a small amount of produced methanol would bring about secondary reactions, because molecular oxygen had been exhausted in the fierce reaction zone. A catalyst, if necessary, should be placed either in the pre-reaction zone, to initiate a partial oxidation reaction at a lower temperature, or in the fierce reaction zone to control the homogeneous free radical reaction.

  5. Quantiles for Finite Mixtures of Normal Distributions

    Science.gov (United States)

    Rahman, Mezbahur; Rahman, Rumanur; Pearson, Larry M.

    2006-01-01

    Quantiles for finite mixtures of normal distributions are computed. The difference between a linear combination of independent normal random variables and a linear combination of independent normal densities is emphasized. (Contains 3 tables and 1 figure.)

  6. A mixture theory for geophysical fluids

    Directory of Open Access Journals (Sweden)

    A. C. Eringen

    2004-01-01

    Full Text Available A continuum theory is developed for a geophysical fluid consisting of two species. Balance laws are given for the individual components of the mixture, modeled as micropolar viscous fluids. The continua allow independent rotational degrees of freedom, so that the fluids can exhibit couple stresses and a non-symmetric stress tensor. The second law of thermodynamics is used to develop constitutive equations. Linear constitutive equations are constituted for a heat conducting mixture, each species possessing separate viscosities. Field equations are obtained and boundary and initial conditions are stated. This theory is relevant to an atmospheric mixture consisting of any two species from rain, snow and/or sand. Also, this is a continuum theory for oceanic mixtures, such as water and silt, or water and oil spills, etc.

  7. The disentangling number for phylogenetic mixtures

    CERN Document Server

    Sullivant, Seth

    2011-01-01

    We provide a logarithmic upper bound for the disentangling number on unordered lists of leaf labeled trees. This results is useful for analyzing phylogenetic mixture models. The proof depends on interpreting multisets of trees as high dimensional contingency tables.

  8. Mapping the jamming transition of bidisperse mixtures

    Science.gov (United States)

    Koeze, D. J.; Vågberg, D.; Tjoa, B. B. T.; Tighe, B. P.

    2016-03-01

    We systematically map out the jamming transition of all 2D bidisperse mixtures of frictionless disks in the hard-particle limit. The critical volume fraction, mean coordination number, number of rattlers, structural order parameters, and bulk modulus each show a rich variation with mixture composition and particle size ratio, and can therefore be tuned by choosing certain mixtures. We identify two local minima in the critical volume fraction, both of which have low structural order; one minimum is close to the widely studied 50 : 50 mixture of particles with a ratio of radii of 1 : 1.4. We also identify a region at low size ratios characterized by increased structural order and high rattler fractions, with a corresponding enhancement in the stiffness.

  9. Ultrafiltration of a polymer-electrolyte mixture

    NARCIS (Netherlands)

    Vonk, P; Noordman, T.R; Schippers, D; Tilstra, B; Wesselingh, J.A

    1997-01-01

    We present a mathematical model to describe the ultrafiltration behaviour of polymer-electrolyte mixtures. The model combines the proper thermodynamic forces (pressure, chemical potential and electrical potential differences) with multicomponent diffusion theory. The model is verified with experimen

  10. Model structure selection in convolutive mixtures

    DEFF Research Database (Denmark)

    Dyrholm, Mads; Makeig, Scott; Hansen, Lars Kai

    2006-01-01

    The CICAAR algorithm (convolutive independent component analysis with an auto-regressive inverse model) allows separation of white (i.i.d) source signals from convolutive mixtures. We introduce a source color model as a simple extension to the CICAAR which allows for a more parsimoneous represent......The CICAAR algorithm (convolutive independent component analysis with an auto-regressive inverse model) allows separation of white (i.i.d) source signals from convolutive mixtures. We introduce a source color model as a simple extension to the CICAAR which allows for a more parsimoneous...... representation in many practical mixtures. The new filter-CICAAR allows Bayesian model selection and can help answer questions like: 'Are we actually dealing with a convolutive mixture?'. We try to answer this question for EEG data....

  11. Model structure selection in convolutive mixtures

    DEFF Research Database (Denmark)

    Dyrholm, Mads; Makeig, S.; Hansen, Lars Kai

    2006-01-01

    The CICAAR algorithm (convolutive independent component analysis with an auto-regressive inverse model) allows separation of white (i.i.d) source signals from convolutive mixtures. We introduce a source color model as a simple extension to the CICAAR which allows for a more parsimonious represent......The CICAAR algorithm (convolutive independent component analysis with an auto-regressive inverse model) allows separation of white (i.i.d) source signals from convolutive mixtures. We introduce a source color model as a simple extension to the CICAAR which allows for a more parsimonious...... representation in many practical mixtures. The new filter-CICAAR allows Bayesian model selection and can help answer questions like: ’Are we actually dealing with a convolutive mixture?’. We try to answer this question for EEG data....

  12. Incomplete reactions in nanothermite composites

    Science.gov (United States)

    Jacob, Rohit J.; Ortiz-Montalvo, Diana L.; Overdeep, Kyle R.; Weihs, Timothy P.; Zachariah, Michael R.

    2017-02-01

    Exothermic reactions between oxophilic metals and transition/post transition metal-oxides have been well documented owing to their fast reaction time scales (≈10 μs). This article examines the extent of the reaction in nano-aluminum based thermite systems through a forensic inspection of the products formed during reaction. Three nanothermite systems (Al/CuO, Al/Bi2O3, and Al/WO3) were selected owing to their diverse combustion characteristics, thereby providing sufficient generality and breadth to the analysis. Microgram quantities of the sample were coated onto a fine platinum wire, which was resistively heated at high heating rates (≈105 K/s) to ignite the sample. The subsequent products were captured/quenched very rapidly (≈500 μs) in order to preserve the chemistry/morphology during initiation and subsequent reaction and were quantitatively analyzed using electron microscopy and focused ion beam cross-sectioning followed by energy dispersive X-ray spectroscopy. Elemental examination of the cross-section of the quenched particles shows that oxygen is predominantly localized in the regions containing aluminum, implying the occurrence of the redox reaction. The Al/CuO system, which has simultaneous gaseous oxygen release and ignition (TIgnition ≈ TOxygen Release), shows a substantially lower oxygen content within the product particles as opposed to Al/Bi2O3 and Al/WO3 thermites, which are postulated to undergo a condensed phase reaction (TIgnition ≪ TOxygen Release). An effective Al:O composition for the interior section was obtained for all the mixtures, with the smaller particles generally showing a higher oxygen content than the larger ones. The observed results were further corroborated with the reaction temperature, obtained using a high-speed spectro-pyrometer, and bomb calorimetry conducted on larger samples (≈15 mg). The results suggest that thermites that produce sufficient amounts of gaseous products generate smaller product particles and

  13. Anesthetic Effects of a Mixture of Medetomidine, Midazolam and Butorphanol in Two Strains of Mice

    Science.gov (United States)

    Kirihara, Yumiko; Takechi, Mayumi; Kurosaki, Kaoru; Kobayashi, Yuta; Kurosawa, Tsutomu

    2013-01-01

    The combination of ketamine and xylazine is a widely used anesthetic for laboratory animals. However, due to an abuse problem in Japan, ketamine has been specified as a narcotic since 2007. Instead of using ketamine, Kawai et al. reported an injectable formula with an equivalent effect to the mixture of ketamine and xylazine [11]. The mixture of 0.3 mg/kg body weight (b.w.) medetomidine (Med.), 4.0 mg/kg b.w. midazoram (Mid.), and 5.0 mg/kg b.w. butorphanol (But.) produced an anesthetic duration of around 40 min in outbred ICR mice. However, the anesthetic effect of the mixture for inbred mice strains remains unknown. Therefore, we examined anesthetic effects of the mixture of Med., Mid., and But. in the BALB/c and C57BL/6J strains. After intraperitoneal injection into mice, right front paw, left hind paw, and tail pinch reflexes as well as corneal and righting reflexes were observed. Every 5 min, we scored each reflex category as 0 for reaction or 1 for no reaction. As long as the total score was at least 4 out of 5, we considered the mixture as putting a mouse in a surgical anesthetic state. The mixture produced an anesthetic duration of more than 45 min in both strains of mice. These results indicate that the mixture of Med., Mid., and But. can be a useful and effective anesthesia for the BALB/c and C57BL/6J strains of inbred mice as well as outbred ICR mice. PMID:23903051

  14. Laboratory performance of asphalt rubber mixtures

    OpenAIRE

    Fontes, Liseane; Trichês, Glicério; Pais, Jorge; Pereira, Paulo; Minhoto, Manuel

    2009-01-01

    Asphalt rubber mixtures are one of the most promising techniques to extend the service life of asphalt pavement overlays. Asphalt rubber binder is composed of crumb rubber from reclaimed tires and conventional asphalt. The asphalt rubber binder can be obtained through wet process in two different systems: tire rubber modified asphalt binder (produced at industrial plants) and continuous blending (produced in asphalt plants). This study presents a laboratory evaluation of asphalt rubber mixtur...

  15. Assessing sanitary mixtures in East African cities

    OpenAIRE

    Letema, S.C.

    2012-01-01

    The urbanisation of poverty and informality in East African cities poses a threat to environmental health, perpetuates social exclusion and inequalities, and creates service gaps (UN-Habitat, 2008). This makes conventional sanitation provision untenable citywide, giving rise to the emergence of sanitation mixtures. Sanitation mixtures have different scales, institutional arrangements, user groups, and rationalities for their establishment, location, and management. For assessing the performan...

  16. Fitting mixture distributions to phenylthiocarbamide (PTC) sensitivity.

    OpenAIRE

    Jones, P N; G.J. McLachlan

    1991-01-01

    A technique for fitting mixture distributions to phenylthiocarbamide (PTC) sensitivity is described. Under the assumptions of Hardy-Weinberg equilibrium, a mixture of three normal components is postulated for the observed distribution, with the mixing parameters corresponding to the proportions of the three genotypes associated with two alleles A and a acting at a single locus. The corresponding genotypes AA, Aa, and aa are then considered to have separate means and variances. This paper is c...

  17. Using Big Data Analytics to Address Mixtures Exposure

    Science.gov (United States)

    The assessment of chemical mixtures is a complex issue for regulators and health scientists. We propose that assessing chemical co-occurrence patterns and prevalence rates is a relatively simple yet powerful approach in characterizing environmental mixtures and mixtures exposure...

  18. Characterization of Dimethylsulfoxide / Glycerol Mixtures: A Binary Solvent System for the Study of "Friction-Dependent" Chemical Reactivity

    CERN Document Server

    Angulo, Gonzalo; Gerecke, Mario; Grampp, Günter; Jeannerat, Damien; Milkiewicz, Jadwiga; Mitrev, Yavor; Radzewicz, Czesław; Rosspeintner, Arnulf; Vauthey, Eric; Wnuk, Paweł

    2016-01-01

    The properties of binary mixtures of dimethylsulfoxide and glycerol, measured by several techniques, are reported. Special attention is given to those properties contributing or affecting chemical reactions. In this respect the investigated mixture behaves as a relatively simple solvent and it is especially well suited for studies on the influence of viscosity in chemical reactivity. This is due to the relative invariance of the dielectric properties of the mixture. However, special caution must be taken with specific solvation, as the hydrogen-bonding properties of the solvent changes with the molar fraction of glycerol.

  19. Characterization of dimethylsulfoxide/glycerol mixtures: a binary solvent system for the study of "friction-dependent" chemical reactivity.

    Science.gov (United States)

    Angulo, Gonzalo; Brucka, Marta; Gerecke, Mario; Grampp, Günter; Jeannerat, Damien; Milkiewicz, Jadwiga; Mitrev, Yavor; Radzewicz, Czesław; Rosspeintner, Arnulf; Vauthey, Eric; Wnuk, Paweł

    2016-07-21

    The properties of binary mixtures of dimethylsulfoxide and glycerol, measured using several techniques, are reported. Special attention is given to those properties contributing or affecting chemical reactions. In this respect the investigated mixture behaves as a relatively simple solvent and it is especially well suited for studies on the influence of viscosity on chemical reactivity. This is due to the relative invariance of the dielectric properties of the mixture. However, special caution must be taken with specific solvation, as the hydrogen-bonding properties of the solvent change with the molar fraction of glycerol.

  20. Catalyst mixture for aromatic hydrocarbon synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Minderhoud, J.K.; Huizinga, T.; Sie, S.T.

    1989-06-06

    The present invention is concerned with catalyst mixtures consisting of two catalysts, characterized in that one, which is based on zinc, is capable of catalysing the conversion of a H/sub 2//CO mixture into oxygen-containing organic compounds, and the other is a crystalline iron/boron silicate which, after one hour's calcination in air at 500/sup 0/C, has the following properties: a certain X-ray powder diffraction pattern and, in the formula that represents the composition of the silicate, expressed in moles of the oxides, a SiO/sub 2//Fe/sub 2/O/sub 3 molar ratio that is 20-2000, a SiO/sub 2//B/sub 2/O/sub 3/ molar ratio 50-5000, and a Fe/sub 2/O/sub 3//B/sub 2/O/sub 3/ molar ratio higher than 1.0. Said catalyst mixtures show higher aromatics selectivity in the preparation of hydrocarbon mixtures from H/sub 2//CO mixtures than such a mixture comprising an iron silicate instead of the above iron/boron silicates. 3 tabs.

  1. Homogeneous cooling of mixtures of particle shapes

    Science.gov (United States)

    Hidalgo, R. C.; Serero, D.; Pöschel, T.

    2016-07-01

    In this work, we examine theoretically the cooling dynamics of binary mixtures of spheres and rods. To this end, we introduce a generalized mean field analytical theory, which describes the free cooling behavior of the mixture. The relevant characteristic time scale for the cooling process is derived, depending on the mixture composition and the aspect ratio of the rods. We simulate mixtures of spherocylinders and spheres using a molecular dynamics algorithm implemented on graphics processing unit (GPU) architecture. We systematically study mixtures composed of spheres and rods with several aspect ratios and varying the mixture composition. A homogeneous cooling state, where the time dependence of the system's intensive variables occurs only through a global granular temperature, is identified. We find cooling dynamics in excellent agreement with Haff's law, when using an adequate time scale. Using the scaling properties of the homogeneous cooling dynamics, we estimated numerically the efficiency of the energy interchange between rotational and translational degrees of freedom for collisions between spheres and rods.

  2. Chemical contaminants on DOE lands and selection of contaminant mixtures for subsurface science research

    Energy Technology Data Exchange (ETDEWEB)

    Riley, R.G.; Zachara, J.M. [Pacific Northwest Lab., Richland, WA (United States)

    1992-04-01

    This report identifies individual contaminants and contaminant mixtures that have been measured in the ground at 91 waste sites at 18 US Department of Energy (DOE) facilities within the weapons complex. The inventory of chemicals and mixtures was used to identify generic chemical mixtures to be used by DOE`s Subsurface Science Program in basic research on the subsurface geochemical and microbiological behavior of mixed contaminants (DOE 1990a and b). The generic mixtures contain specific radionuclides, metals, organic ligands, organic solvents, fuel hydrocarbons, and polychlorinated biphenyls (PCBs) in various binary and ternary combinations. The mixtures are representative of in-ground contaminant associations at DOE facilities that are likely to exhibit complex geochemical behavior as a result of intercontaminant reactions and/or microbiologic activity stimulated by organic substances. Use of the generic mixtures will focus research on important mixed contaminants that are likely to be long-term problems at DOE sites and that will require cleanup or remediation. The report provides information on the frequency of associations among different chemicals and compound classes at DOE waste sites that require remediation.

  3. Chemical contaminants on DOE lands and selection of contaminant mixtures for subsurface science research

    Energy Technology Data Exchange (ETDEWEB)

    Riley, R.G.; Zachara, J.M. (Pacific Northwest Lab., Richland, WA (United States))

    1992-04-01

    This report identifies individual contaminants and contaminant mixtures that have been measured in the ground at 91 waste sites at 18 US Department of Energy (DOE) facilities within the weapons complex. The inventory of chemicals and mixtures was used to identify generic chemical mixtures to be used by DOE's Subsurface Science Program in basic research on the subsurface geochemical and microbiological behavior of mixed contaminants (DOE 1990a and b). The generic mixtures contain specific radionuclides, metals, organic ligands, organic solvents, fuel hydrocarbons, and polychlorinated biphenyls (PCBs) in various binary and ternary combinations. The mixtures are representative of in-ground contaminant associations at DOE facilities that are likely to exhibit complex geochemical behavior as a result of intercontaminant reactions and/or microbiologic activity stimulated by organic substances. Use of the generic mixtures will focus research on important mixed contaminants that are likely to be long-term problems at DOE sites and that will require cleanup or remediation. The report provides information on the frequency of associations among different chemicals and compound classes at DOE waste sites that require remediation.

  4. Dynamics of Feshbach Molecules in an Ultracold Three-Component Mixture

    CERN Document Server

    Khramov, A Y; Jamison, A O; Dowd, W H; Gupta, S

    2012-01-01

    We present investigations of the formation rate and collisional stability of lithium Feshbach molecules in an ultracold three-component mixture composed of two resonantly interacting fermionic 6-Li spin states and bosonic 174-Yb. We observe long molecule lifetimes (> 100 ms) even in the presence of a large ytterbium bath and extract reaction rate coefficients of the system. We find good collisional stability of the mixture in the unitary regime, opening new possibilities for studies and probes of strongly interacting quantum gases in contact with a bath species.

  5. Catalysis of Photochemical Reactions.

    Science.gov (United States)

    Albini, A.

    1986-01-01

    Offers a classification system of catalytic effects in photochemical reactions, contrasting characteristic properties of photochemical and thermal reactions. Discusses catalysis and sensitization, examples of catalyzed reactions of excepted states, complexing ground state substrates, and catalysis of primary photoproducts. (JM)

  6. When mixtures of hard-sphere-like colloids do not behave as mixtures of hard spheres.

    Science.gov (United States)

    Germain, Ph; Malherbe, J G; Amokrane, S

    2004-10-01

    The validity of the concept of "hard-sphere-like" particles for mixtures of colloids is questioned from a theoretical point of view. This concerns the class of pseudobinary mixtures in which the nonsteric interactions between the colloids are "residual" (with very small range and moderate strength). It is shown that contrary to common expectation, such interactions may have unexpected consequences on the theoretical phase diagram. The distinction between this situation and true solute-solvent mixtures is emphasized.

  7. [Allergic reactions to transfusion].

    Science.gov (United States)

    Hergon, E; Paitre, M L; Coeffic, B; Piard, N; Bidet, J M

    1987-04-01

    Frequent allergic reactions following transfusion are observed. Usually, they are benign but sometimes we observe severe allergic reactions. Adverse reactions may be brought about by least two mechanisms. First, immediate-type hypersensibility reactions due to IgE. Secondly, anaphylactic-type reactions due to interaction between transfused IgA and class specific anti IgA in the recipient's plasma. They are characterized by their severest form (anaphylactic shock). The frequency of severe reactions following the transfusion blood plasma is very low. These transfusion reactions are complement-mediated and kinins-mediated. Prevention of allergic reactions is necessary among blood donors and recipients.

  8. Decolorization of mixtures of different reactive textile dyes by the white-rot basidiomycete Phanerochaete sordida and inhibitory effect of polyvinyl alcohol.

    Science.gov (United States)

    Harazono, Koichi; Nakamura, Kazunori

    2005-03-01

    We tried to decolorize mixtures of four reactive textile dyes, including azo and anthraquinone dyes, by a white-rot basidiomycete Phanerochaete sordida. P. sordida decolorized dye mixtures (200 mg l-1 each) by 90% within 48 h in nitrogen-limited glucose-ammonium media. Decolorization of dye mixtures needed Mn2+ and Tween 80 in the media. Manganese peroxidase (MnP) played a major role in dye decolorization by P. sordida. Decolorization of dye mixtures by P. sordida was partially inhibited by polyvinyl alcohol (PVA) that wastewaters from textile industries often contain. This was caused by an inhibitory effect of PVA on the decolorization of Reactive Red 120 (RR120) with MnP reaction system. Second addition of Tween 80 to the reaction mixtures in the presence of PVA improved the decolorization of RR120. These results suggest that PVA could interfere with lipid peroxidation or subsequent attack to the dye.

  9. Fluctuating hydrodynamics of multi-species reactive mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, Amit Kumar; Donev, Aleksandar [Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, New York 10012 (United States); Balakrishnan, Kaushik [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109 (United States); Garcia, Alejandro L. [Department of Physics and Astronomy, San Jose State University, 1 Washington Square, San Jose, California 95192 (United States); Bell, John B. [Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)

    2015-06-14

    We formulate and study computationally the fluctuating compressible Navier-Stokes equations for reactive multi-species fluid mixtures. We contrast two different expressions for the covariance of the stochastic chemical production rate in the Langevin formulation of stochastic chemistry, and compare both of them to predictions of the chemical master equation for homogeneous well-mixed systems close to and far from thermodynamic equilibrium. We develop a numerical scheme for inhomogeneous reactive flows, based on our previous methods for non-reactive mixtures [Balakrishnan , Phys. Rev. E 89, 013017 (2014)]. We study the suppression of non-equilibrium long-ranged correlations of concentration fluctuations by chemical reactions, as well as the enhancement of pattern formation by spontaneous fluctuations. Good agreement with available theory demonstrates that the formulation is robust and a useful tool in the study of fluctuations in reactive multi-species fluids. At the same time, several problems with Langevin formulations of stochastic chemistry are identified, suggesting that future work should examine combining Langevin and master equation descriptions of hydrodynamic and chemical fluctuations.

  10. Ultra dispersed mixture of PETN and RDX for explosive welding

    Science.gov (United States)

    Ten, K. A.; Pruuel, E. R.; Kashkarov, A. O.; Rubtsov, I. A.; Spirin, I. A.; Mikhailov, A. L.; Shekhtman, L. I.; Zhulanov, V. V.; Deribas, A. A.

    2016-10-01

    Mixed formulations of ultrafine PETN+soda and RDX+soda have low detonation velocity and small critical diameters, which makes them attractive for application to new technological processes, such as welding explosion [1]. The above properties of these formulations are due to the use of nanopowders of PETN and RDX along with a phlegmatizing agent of sodium bicarbonate. The detonation parameters of these mixtures were studied using synchrotron radiation from the VEPP-3 accelerator (Budker Institute of Nuclear Physics). Techniques we developed were applied to the measurement of density distribution in the detonation front and the width of the reaction zone, as well as volume distribution of pressure, density and spread velocities in detonation of cylindrical charges.

  11. Crystallization of Carbon Oxygen Mixtures in White Dwarf Stars

    CERN Document Server

    Horowitz, C J; Berry, D K

    2010-01-01

    We determine the phase diagram for dense carbon/ oxygen mixtures in White Dwarf (WD) star interiors using molecular dynamics simulations involving liquid and solid phases. Our phase diagram agrees well with predictions from Ogata et al. and Medin and Cumming and gives lower melting temperatures than Segretain et al. Observations of WD crystallization in the globular cluster NGC 6397 by Winget et al. suggest that the melting temperature of WD cores is close to that for pure carbon. If this is true, our phase diagram implies that the central oxygen abundance in these stars is less than about 60%. This constraint, along with assumptions about convection in stellar evolution models, limits the effective S factor for the $^{12}$C($\\alpha,\\gamma$)$^{16}$O reaction to S_{300} <= 170 keV barns.

  12. A new kind of Molotov? Gasoline-pool chlorinator mixtures.

    Science.gov (United States)

    Hutches, Katherine; Lord, James

    2012-07-01

    This paper investigates the reaction between pool chlorinators and gasoline. In particular, the propensity for self-ignition and the resulting chemical products were studied. An organic pool chlorinator was combined with gasoline in varying proportions in an attempt to form a hypergolic mixture. None of the combinations resulted in self-ignition, but larger quantities of chlorinator produced vigorous light-colored smoke and a solid mass containing isocyanuric acid and copper chloride. Additionally, the chlorinating abilities of different commercially available pool chlorinators were explored. When Ca(ClO)(2) and sodium dichloro-s-triazinetrione-based chlorinators were used, the presence of gasoline was still visible after 10 days, despite limited chlorination. The trichloro-s-triazinetrione-based chlorinator, however, caused efficient chlorination of the C(2)- and C(3)-alkylbenzenes, making gasoline no longer identifiable.

  13. Selective solar photodegradation of organopollutant mixtures in water

    Energy Technology Data Exchange (ETDEWEB)

    Robert, D.; Piscopo, A.; Weber, J.V. [Metz Univ., Saint-Avold (France). Lab. de Chimie et Applications

    2004-11-01

    Heterogeneous photocatalysis in a water solution is recognised as a method of totally eliminating most recalcitrant organic pollutants found in such solutions. Our current work has tried to show that the heterogeneous photocatalysis process can also be a selective elimination method in the case of the mixture: 4-hydroxybenzoic acid (4-HBz) and benzamide (Bz) at semi-pilot plant scale (190 dm{sup 3}) under conditions of solar irradiation. The photocatalysis experiments performed by us were done at the 'Plataforma Solar de Almeria' and were carried out in the compound parabolic collectors' CPC system. We investigated in particular the influence of TiO{sub 2} loading, the effect of 4-HBz concentration and the effect of the presence of chloride anions and pH on the selectivity of the reaction process. (Author)

  14. Electron-induced hydration of an alkene: alternative reaction pathways.

    Science.gov (United States)

    Warneke, Jonas; Wang, Ziyan; Swiderek, Petra; Bredehöft, Jan Hendrik

    2015-03-27

    Electron-induced reactions in condensed mixtures of ethylene and water lead to the synthesis of ethanol, as shown by post-irradiation thermal desorption spectrometry (TDS). Interestingly, this synthesis is not only induced by soft electron impact ionization similar to a previously observed electron-induced hydroamination but also, at low electron energy, by electron attachment to ethylene and a subsequent acid/base reaction with water.

  15. Belousov-Zhabotinsky oscillatory reaction. Kinetics of malonic acid decomposition

    Directory of Open Access Journals (Sweden)

    LJILJANA KOLAR-ANIC

    2000-10-01

    Full Text Available The kinetics of the Belousov-Zhabotinsky (BZ oscillatory reaction was analyzed. With this aim, the time evolution of a reaction mixture composed of malonic acid, bromate, sulfuric acid and cerium(III was studied at 298 K. Pseudo-first order kinetics with respect to malonic acid as the species undergoing decomposition with a corresponding rate constant, k = 7.5×10-3 min-1, was found.

  16. Identifiability of large phylogenetic mixture models.

    Science.gov (United States)

    Rhodes, John A; Sullivant, Seth

    2012-01-01

    Phylogenetic mixture models are statistical models of character evolution allowing for heterogeneity. Each of the classes in some unknown partition of the characters may evolve by different processes, or even along different trees. Such models are of increasing interest for data analysis, as they can capture the variety of evolutionary processes that may be occurring across long sequences of DNA or proteins. The fundamental question of whether parameters of such a model are identifiable is difficult to address, due to the complexity of the parameterization. Identifiability is, however, essential to their use for statistical inference.We analyze mixture models on large trees, with many mixture components, showing that both numerical and tree parameters are indeed identifiable in these models when all trees are the same. This provides a theoretical justification for some current empirical studies, and indicates that extensions to even more mixture components should be theoretically well behaved. We also extend our results to certain mixtures on different trees, using the same algebraic techniques.

  17. Relativistic mixtures of charged and uncharged particles

    Energy Technology Data Exchange (ETDEWEB)

    Kremer, Gilberto M. [Departamento de Física, Universidade Federal do Paraná, Curitiba (Brazil)

    2014-01-14

    Mixtures of relativistic gases within the framework of Boltzmann equation are analyzed. Three systems are considered. The first one refers to a mixture of uncharged particles by using Grad’s moment method, where the relativistic mixture is characterized by the moments of the distribution functions: particle four-flows, energy-momentum tensors, and third-order moment tensors. In the second Fick’s law for a mixture of relativistic gases of non-disparate rest masses in a Schwarzschild metric are derived from an extension of Marle and McCormack model equations applied to a relativistic truncated Grad’s distribution function, where it is shown the dependence of the diffusion coefficient on the gravitational potential. The third one consists in the derivation of the relativistic laws of Ohm and Fourier for a binary mixtures of electrons with protons and electrons with photons subjected to external electromagnetic fields and in presence of gravitational fields by using the Anderson and Witting model of the Boltzmann equation.

  18. Microsiemens or Milligrams: Measures of Ionic Mixtures ...

    Science.gov (United States)

    In December of 2016, EPA released the Draft Field-Based Methods for Developing Aquatic Life Criteria for Specific Conductivity for public comment. Once final, states and authorized tribes may use these methods to derive field-based ecoregional ambient Aquatic Life Ambient Water Quality Criteria (AWQC) for specific conductivity (SC) in flowing waters. The methods provide flexible approaches for developing science-based SC criteria that reflect ecoregional or state specific factors. The concentration of a dissolved salt mixture can be measured in a number of ways including measurement of total dissolved solids, freezing point depression, refractive index, density, or the sum of the concentrations of individually measured ions. For the draft method, SC was selected as the measure because SC is a measure of all ions in the mixture; the measurement technology is fast, inexpensive, and accurate, and it measures only dissolved ions. When developing water quality criteria for major ions, some stakeholders may prefer to identify the ionic constituents as a measure of exposure instead of SC. A field-based method was used to derive example chronic and acute water quality criteria for SC and two anions a common mixture of ions (bicarbonate plus sulfate, [HCO3−] + [SO42−] in mg/L) that represent common mixtures in streams. These two anions are sufficient to model the ion mixture and SC (R2 = 0.94). Using [HCO3−] + [SO42−] does not imply that these two anions are the

  19. ASPECTS OF THERMODYNAMICS OF POLYMER MIXTURES

    Institute of Scientific and Technical Information of China (English)

    CHAI Zhikuan

    1987-01-01

    In this brief review article some aspects of the thermodynamics of polymer mixtures are discussed,mainly based on the author's research. The studies of poly (methyl methacrylate)/chlorinated polyethylene (CPE), poly (butyl acrylate)/CPE and CPE/CPE (different chlorine content) mixture verify the "dissimilarity" and "similarity" principles for predicting miscibility of polymer mixtures. The sign of heat of mixing of oligomeric analogues is not sufficient in predicting the miscibility. The Flory equation of state theory has been applied to simulate the phase boundaries of polymer mixtures. The empirical entropy parameter Q12 plays an important role in the calculation, this reduces the usefulness of the theory. With energy parameter X12 ≠ 0 and Q12 ≠ 0 the spinodals so calculated are reasonable compared to experiments.A hole model was suggested for the statistics of polymer mixtures. The new hole theory combines the features of both the Flory equation of state theory and the Sanchez lattice fluid theory and can be reduced to them under some conditions.

  20. A constitutive theory of reacting electrolyte mixtures

    Science.gov (United States)

    Costa Reis, Martina; Wang, Yongqi; Bono Maurizio Sacchi Bassi, Adalberto

    2013-11-01

    A constitutive theory of reacting electrolyte mixtures is formulated. The intermolecular interactions among the constituents of the mixture are accounted for through additional freedom degrees to each constituent of the mixture. Balance equations for polar reacting continuum mixtures are accordingly formulated and a proper set of constitutive equations is derived with basis in the Müller-Liu formulation of the second law of thermodynamics. Moreover, the non-equilibrium and equilibrium responses of the reacting mixture are investigated in detail by emphasizing the inner and reactive structures of the medium. From the balance laws and constitutive relations, the effects of molecular structure of constituents upon the fluid flow are studied. It is also demonstrated that the local thermodynamic equilibrium state can be reached without imposing that the set of independent constitutive variables is time independent, neither spatially homogeneous nor null. The resulting constitutive relations presented throughout this work are of relevance to many practical applications, such as swelling of clays, developing of bio and polymeric membranes, and use of electrorheological fluids in industrial processes. The first author acknowledges financial support from National Counsel of Technological and Scientific Development (CNPq) and German Academic Exchange Service (DAAD).

  1. Asbestos Tailings as Aggregates for Asphalt Mixture

    Institute of Scientific and Technical Information of China (English)

    LIU Xinoming; XU Linrong

    2011-01-01

    To use many asbestos tailings collected in Ya-Lu highway, and to explore the feasibility of using asbestos tailings as aggregates in common asphalt mixtures, and properties of some asphalt mixtures were evaluated as well. X-ray diffraction (XRD), X-ray fluorescent (XRF), and atomic absorption spectrophotometry (AAS) were employed to determine the solid waste content of copper, zinc, lead, and cadmium. Volume properties and pavement performances of AC-25 asphalt mixture with asbestos tailings were also evaluated compared with those with basalt as aggregates.XRD and XRF measurement results infer that asbestos tailing is an excellent road material. Volume properties of AC-25 asphalt mixture with asbestos tailings satisfied the related specifications. No heavy metals and toxic pollution were detected in AAS test and the value of pH test is 8.23, which is help to the adhesion with asphalt in the asphalt concrete. When compared with basalt, high temperature property and the resistance to low temperature cracking of AC-25 asphalt mixture was improved by using asbestos tailings as aggregates. In-service AC-25 asphalt pavement with asbestos tailings also presented excellent performance and British Pendulum Number (BPN) coefficient of surface.

  2. Effect of an allophanic soil on humification reactions between catechol and glycine: Spectroscopic investigations of reaction products

    Science.gov (United States)

    Fukushima, Masami; Miura, Akitaka; Sasaki, Masahide; Izumo, Kenji

    2009-01-01

    Adduction of amino acids to phenols is a possible humification reaction pathway [F.J. Stevenson, Humus Chemistry: Genesis, Composition, Reaction, second ed., Wiley, New York, 1994, pp. 188-211; M.C. Wang, P.M. Huang, Sci. Total Environ. 62 (1987) 435; M.C. Wang, P.M. Huang, Soil Sci. Soc. Am. J. 55 (1991) 1156; M.C. Wang, P.M. Huang, Geoderma 112 (2003) 31; M.C. Wang, P.M. Huang, Geoderma 124 (2005) 415]. To elucidate the reaction kinetics and products of abiotic humification, the effects of an allophanic soil on the adduction of amino acids to phenols were investigated using catechol (CT) and glycine (Gly) as a model phenol and amino acid, respectively. An aqueous solution containing CT and Gly (pH 7.0) in the presence of allophanic soil was incubated for 2 weeks, and the kinetics of the humification reactions were monitored by analysis of absorptivity at 600 nm ( E600). A mixture of CT and Gly in the absence of allophanic soil was used as a control. The E600 value increased markedly in the presence of allophanic soil. In addition, unreacted CT was detected in the control reaction mixture, but not in the allophane-containing reaction mixture. Under the sterilized conditions, absorbance at 600 nm for the control reaction mixture was significantly smaller than that for the allophanic soil-containing reaction mixture, which indicates there was no microbial participation during incubation. These results indicate that the allophanic soil effectively facilitated humification reactions between CT and Gly. The reaction mixtures were acidified and humic-like acid (HLA) was isolated as a precipitate. The elemental composition, acidic functional group contents, molecular weight, FT-IR, solid-state CP-MAS 13C NMR, and 1H NMR spectra of the purified HLAs were analyzed. The results of these analyses indicate that the nitrogen atom of Gly binds to the aromatic carbon of CT in the HLA products.

  3. Radiation-induced graft copolymerization of binary monomer mixture containing acrylonitrile onto polyethylene films

    Science.gov (United States)

    Choi, Seong-Ho; Nho, Young Chang

    2000-04-01

    Graft copolymerization of acrylonitrile (AN)/acrylic acid (AA), acrylonitrile (AN)/methacrylic acid (MA), and acrylonitrile (AN)/glycidyl methacrylate (GMA) onto pre-irradiated polyethylene (PE) films were studied. The effect of reaction conditions such as solvents, additives, and monomer composition on the grafting yields was investigated. The extent of grafting was found to increase with increasing sulfuric acid concentration when sulfuric acid as an additive was added to the grafting solution. In AN/AA mixture, the proportion of acrylonitrile in the copolymer increased with an increasing AN component in feed monomers. On the other hand, in AN/MA mixture, acrylonitrile component in copolymer was very slight in spite of the increase AN component in feed monomers. In the AN/GMA mixture, the proportion of acrylonitrile in the copolymer increased with increasing acrylonitrile component in AN/GMA feed monomer.

  4. Toxaphene chemistry: separation and characterisation of selected enantiomers of the Polychloropinene mixtures.

    Science.gov (United States)

    Trukhin, Alexey; Kruchkov, Fedor; Hansen, Lars Kr; Kallenborn, Roland; Kiprianova, Anastasia; Nikiforov, Vladimir

    2007-04-01

    The primary goal for the study presented here was the preparation and characterisation of enantiomeric pure chlorobornane standards (Toxaphene). In this context, we partially modeled the procedure for Polychloropinene production in the former USSR. The initial reaction was ionic addition of hydrogen chloride to (1S)-alpha-pinene resulting predominantly in (1S)-2-endo-chlorobornane. Further photochlorination gave mixtures of chlorinated terpenes with different average content of Cl per molecule. The resulting mixtures were separated on a silica-gel column and a number of known hepta to decachlorobornanes were identified in fractions with the help of NMR and GC (using electron capture and mass spectrometric detection)--but in very unusual ratios as compared to the technical Toxaphene mixture formerly produced by Hercules (USA). Also several previously unknown congeners were isolated or detected. Three of the isolated congeners were obtained in crystalline state and X-ray crystallography showed their enantiomeric purity.

  5. A cold energy mixture theory for the equation of state in solid and porous metal mixtures

    Science.gov (United States)

    Zhang, X. F.; Qiao, L.; Shi, A. S.; Zhang, J.; Guan, Z. W.

    2011-07-01

    Porous or solid multi-component mixtures are ubiquitous in nature and extensively used as industrial materials such as multifunctional energetic structural materials (MESMs), metallic and ceramic powder for shock consolidation, and porous armor materials. In order to analyze the dynamic behavior of a particular solid or porous metal mixture in any given situation, a model is developed to calculate the Hugoniot data for solid or porous mixtures using only static thermodynamic properties of the components. The model applies the cold energy mixture theory to calculate the isotherm of the components to avoid temperature effects on the mixtures. The isobaric contribution from the thermodynamic equation of state is used to describe the porous material Hugoniot. Dynamic shock responses of solid or porous powder mixtures compacted by shock waves have been analyzed based on the mixture theory and Hugoniot for porous materials. The model is tested on both single-component porous materials such as aluminum 2024, copper, and iron; and on multi-component mixtures such as W/Cu, Fe/Ni, and Al/Ni. The theoretical calculations agree well with the corresponding experimental and simulation results. The present model produces satisfactory correlation with the experimentally obtained Hugoniot data for solid porous materials over a wide pressure range.

  6. Adaptive Mixture Methods Based on Bregman Divergences

    CERN Document Server

    Donmez, Mehmet A; Kozat, Suleyman S

    2012-01-01

    We investigate adaptive mixture methods that linearly combine outputs of $m$ constituent filters running in parallel to model a desired signal. We use "Bregman divergences" and obtain certain multiplicative updates to train the linear combination weights under an affine constraint or without any constraints. We use unnormalized relative entropy and relative entropy to define two different Bregman divergences that produce an unnormalized exponentiated gradient update and a normalized exponentiated gradient update on the mixture weights, respectively. We then carry out the mean and the mean-square transient analysis of these adaptive algorithms when they are used to combine outputs of $m$ constituent filters. We illustrate the accuracy of our results and demonstrate the effectiveness of these updates for sparse mixture systems.

  7. Computer simulation of rod-sphere mixtures

    CERN Document Server

    Antypov, D

    2003-01-01

    Results are presented from a series of simulations undertaken to investigate the effect of adding small spherical particles to a fluid of rods which would otherwise represent a liquid crystalline (LC) substance. Firstly, a bulk mixture of Hard Gaussian Overlap particles with an aspect ratio of 3:1 and hard spheres with diameters equal to the breadth of the rods is simulated at various sphere concentrations. Both mixing-demixing and isotropic-nematic transition are studied using Monte Carlo techniques. Secondly, the effect of adding Lennard-Jones particles to an LC system modelled using the well established Gay-Berne potential is investigated. These rod-sphere mixtures are simulated using both the original set of interaction parameters and a modified version of the rod-sphere potential proposed in this work. The subject of interest is the internal structure of the binary mixture and its dependence on density, temperature, concentration and various parameters characterising the intermolecular interactions. Both...

  8. Quasi-chemical approximation for polyatomic mixtures

    CERN Document Server

    Dávila, M V; Matoz-Fernandez, D A; Ramirez-Pastor, A J

    2016-01-01

    The statistical thermodynamics of binary mixtures of polyatomic species was developed on a generalization in the spirit of the lattice-gas model and the quasi-chemical approximation (QCA). The new theoretical framework is obtained by combining: (i) the exact analytical expression for the partition function of non-interacting mixtures of linear $k$-mers and $l$-mers (species occupying $k$ sites and $l$ sites, respectively) adsorbed in one dimension, and its extension to higher dimensions; and (ii) a generalization of the classical QCA for multicomponent adsorbates and multisite-occupancy adsorption. The process is analyzed through the partial adsorption isotherms corresponding to both species of the mixture. Comparisons with analytical data from Bragg-Williams approximation (BWA) and Monte Carlo simulations are performed in order to test the validity of the theoretical model. Even though a good fitting is obtained from BWA, it is found that QCA provides a more accurate description of the phenomenon of adsorpti...

  9. Efficient radiative transfer in dust grain mixtures

    CERN Document Server

    Wolf, S

    2003-01-01

    The influence of a dust grain mixture consisting of spherical dust grains with different radii and/or chemical composition on the resulting temperature structure and spectral energy distribution of a circumstellar shell is investigated. The comparison with the results based on an approximation of dust grain parameters representing the mean optical properties of the corresponding dust grain mixture reveal that (1) the temperature dispersion of a real dust grain mixture decreases substantially with increasing optical depth, converging towards the temperature distribution resulting from the approximation of mean dust grain parameters, and (2) the resulting spectral energy distributions do not differ by more than 10% if >= 2^5 grain sizes are considered which justifies the mean parameter approximation and the many results obtained under its assumption so far. Nevertheless, the dust grain temperature dispersion at the inner boundary of a dust shell may amount to >>100K and has therefore to be considered in the cor...

  10. Two-Microphone Separation of Speech Mixtures

    DEFF Research Database (Denmark)

    Pedersen, Michael Syskind; Wang, DeLiang; Larsen, Jan

    2008-01-01

    Separation of speech mixtures, often referred to as the cocktail party problem, has been studied for decades. In many source separation tasks, the separation method is limited by the assumption of at least as many sensors as sources. Further, many methods require that the number of signals within...... the recorded mixtures be known in advance. In many real-world applications, these limitations are too restrictive. We propose a novel method for underdetermined blind source separation using an instantaneous mixing model which assumes closely spaced microphones. Two source separation techniques have been...... similar signals. Using two microphones, we can separate, in principle, an arbitrary number of mixed speech signals. We show separation results for mixtures with as many as seven speech signals under instantaneous conditions. We also show that the proposed method is applicable to segregate speech signals...

  11. How NO{sub 2} affects the reaction mechanism of the SCR reaction

    Energy Technology Data Exchange (ETDEWEB)

    Koebel, M.; Madia, G.; Raimondo, F.; Wokaun, A.

    2003-03-01

    The rate of the selective catalytic reduction (SCR) of NO with N-containing reducing agents may be considerably enhanced by converting part of the NO into NO{sub 2}. The reaction using an equimolar mixture of NO and NO{sub 2} is known as 'fast SCR reaction' and the rate enhancement is most pronounced at low temperatures (T<300{sup o}C). In the present work the possible role of NO{sub 2} on catalysts based on TiO{sub 2}-WO{sub 3}-V{sub 2}O{sub 5} was investigated by in-situ Raman spectroscopy. The experiments suggest that the V{sup +4} species formed during the reduction of NO with ammonia are reoxidized faster by NO{sub 2} than by oxygen, resulting in an increased reaction rate of the fast SCR reaction. (author)

  12. Modeling methods for mixture-of-mixtures experiments applied to a tablet formulation problem.

    Science.gov (United States)

    Piepel, G F

    1999-01-01

    During the past few years, statistical methods for the experimental design, modeling, and optimization of mixture experiments have been widely applied to drug formulation problems. Different methods are required for mixture-of-mixtures (MoM) experiments in which a formulation is a mixture of two or more "major" components, each of which is a mixture of one or more "minor" components. Two types of MoM experiments are briefly described. A tablet formulation optimization example from a 1997 article in this journal is used to illustrate one type of MoM experiment and corresponding empirical modeling methods. Literature references that discuss other methods for MoM experiments are also provided.

  13. Mutation spectra of complex environmental mixtures

    Energy Technology Data Exchange (ETDEWEB)

    DeMarini, D.M. [EPA, Research Triangle Park, NC (United States)

    1997-10-01

    Bioassay-directed chemical analysis of complex environmental mixtures has indicated that much of the genotoxic activity of mixtures is due to the presence of one or a few classes or chemicals within the mixture. We have extended this observation to the molecular level by using colony probe hybridization and PCR/DNA sequence analysis to determine the mutation spectra of {approximately}8,000 revertants induced by a variety of complex mixtures and their chemical fractions in TA100 and TA98 of Salmonella. For urban air, >80% of mutagenic activity was due to a base/neutral fraction that contained primarily PAHs. The mutation spectrum induced by unfractionated urban air was not significantly different from that produced by a model PAH, B(a)P. The mutation spectrum induced by organic extracts of chlorinated drinking water were similar to those produced by the chlorinated furanone MX, which accounted for {approximately}20% of the mutagenic activity of the samples. The base/neutral fraction of municipal waste incinerator emissions accounted for the primary class of mutations induced by the emissions, and a polar neutral fraction accounted for the secondary class of mutations induced by the emissions. The primary class of mutations induced by cigarette smoke condensate in TA100 (GC {yields} TA) is also the primary class of mutations in the p53 gene of lung tumors of cigarette smokers. These results confirm at the molecular level that the mutations induced by a complex mixture reflect the dominance of one or a few classes of chemicals within the mixture.

  14. Thermophysical Properties of Fluids and Fluid Mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Sengers, Jan V.; Anisimov, Mikhail A.

    2004-05-03

    The major goal of the project was to study the effect of critical fluctuations on the thermophysical properties and phase behavior of fluids and fluid mixtures. Long-range fluctuations appear because of the presence of critical phase transitions. A global theory of critical fluctuations was developed and applied to represent thermodynamic properties and transport properties of molecular fluids and fluid mixtures. In the second phase of the project, the theory was extended to deal with critical fluctuations in complex fluids such as polymer solutions and electrolyte solutions. The theoretical predictions have been confirmed by computer simulations and by light-scattering experiments. Fluctuations in fluids in nonequilibrium states have also been investigated.

  15. Paternity testing that involves a DNA mixture.

    Science.gov (United States)

    Mortera, Julia; Vecchiotti, Carla; Zoppis, Silvia; Merigioli, Sara

    2016-07-01

    Here we analyse a complex disputed paternity case, where the DNA of the putative father was extracted from his corpse that had been inhumed for over 20 years. This DNA was contaminated and appears to be a mixture of at least two individuals. Furthermore, the mother's DNA was not available. The DNA mixture was analysed so as to predict the most probable genotypes of each contributor. The major contributor's profile was then used to compute the likelihood ratio for paternity. We also show how to take into account a dropout allele and the possibility of mutation in paternity testing.

  16. Mixture Distribution Approach In Financial Risk Analysis

    OpenAIRE

    Kocak, Keziban; Calis, Nazif; Unal, Deniz

    2014-01-01

    In recent years, major changes occurred in the prices of stock exchange appeared the necessity of measuring the financial risk. Nowadays, Value-atRisk (VaR) is often used to calculate the financial risk. Parametric methods which need normality are mostly used in the calculation of VaR.If the financial data does not fit the normal distribution, mixture of normal distribution models can be fitted to this data. In this study, the financial risk is calculated by using normal mixture distribution ...

  17. Boiler derating for coal-water mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Horney, F.A.; Nolte, F.S.

    1983-11-01

    The authors demonstrated a method for approximating the derating required when converting an oil or natural gas fired unit to a coal-water mixture. If the results show that a retrofit to coal-water mixture appears economically reasonable, then a more detailed analysis should be made by the boiler manufacturer whose methods are more precise than the methods of this paper. The expense of having the boiler manufacturer make a precise analysis can be avoided if the results of the analysis of this paper show conversion not to be viable.

  18. Conditional Density Approximations with Mixtures of Polynomials

    DEFF Research Database (Denmark)

    Varando, Gherardo; López-Cruz, Pedro L.; Nielsen, Thomas Dyhre

    2015-01-01

    Mixtures of polynomials (MoPs) are a non-parametric density estimation technique especially designed for hybrid Bayesian networks with continuous and discrete variables. Algorithms to learn one- and multi-dimensional (marginal) MoPs from data have recently been proposed. In this paper we introduce...... is found. We illustrate and study the methods using data sampled from known parametric distributions, and we demonstrate their applicability by learning models based on real neuroscience data. Finally, we compare the performance of the proposed methods with an approach for learning mixtures of truncated...

  19. Mixture for removing tar and paraffin deposits

    Energy Technology Data Exchange (ETDEWEB)

    kamenshchikov, F.A.; Frolov, M.A.; Golovin, I.N.; Khusainov, Z.M.; Smirnov, Ya.L.; Suchkov, B.M.

    1981-05-23

    Mixture is claimed for removing tar and paraffin deposits (TPD) on the basis of the butyl-benzene fraction (BBF), which is intended to more efficiently remove TPD from the surface of refinery equipment, additionally has piperylene, isoprene and isoamine with the following ratio of the components: piperylene, 19-31%; isoprene, 8-12%; isoamines, 8-12%, while BBF, the rest. The efficiency of the given compositions was assessed by the rate at which the plates were cleaned of TPD and pure commercial paraffin. It has been shown that BBF dissolves 4-6 times faster in the given mixture than in BBF and pyperylene.

  20. Viscosity of oil and water mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Corlett, A.E.; Hall, A.R.W. [National Engineering Laboratory, Glasgow (United Kingdom)

    1999-07-01

    A study was performed to investigate the apparent viscosity of oil and water mixtures using the pressure loss along a horizontal pipe. Water fractions between 100% to 5% were examined at three flow velocities and three temperatures. Four combinations of crude oil and saline solution were used. Tests found that the mixture viscosity exhibited a peak at the position of phase inversion. The value of this maximum viscosity depended upon the temperature and fluid combination used, but not the velocity. Physical properties of the fluids were important factors in the viscosity/water fraction behaviour. (author)