Sample records for acid hybridization reactions

  1. Understanding the mechanisms of reaction and release of acid–base indicators entrapped in hybrid gels

    Microsoft Academic Search

    Zhijian Wu; Yan Jiang; Hong Xiang; Laijiang You

    2006-01-01

    The reactivity and release of acid–base indicators entrapped in silica and hybrid silica gels were studied. Methyl orange (MO), methyl red (MR), and phenyl red (PR) were used as the indicators. Tetraethoxysilane (TEOS), n-propyltriethoxysilane (PTES), and bis(trimethoxysilyl)hexane (TSH) were used as gel precursors. HCl (0.01M) and NaOH (0.01M) solutions were used as the media for acid–base reaction and release in

  2. Sensitive electrochemical monitoring of nucleic acids coupling DNA nanostructures with hybridization chain reaction.

    PubMed

    Zhuang, Junyang; Fu, Libing; Xu, Mingdi; Yang, Huanghao; Chen, Guonan; Tang, Dianping

    2013-06-14

    Methods based on metal nanotags have been developed for metallobioassay of nucleic acids, but most involve complicated labeling or stripping procedures and are unsuitable for routine use. Herein, we report the proof-of-concept of a novel and label-free metallobioassay for ultrasensitive electronic determination of human immunodeficiency virus (HIV)-related gene fragments at an ultralow concentration based on target-triggered long-range self-assembled DNA nanostructures and DNA-based hybridization chain reaction (HCR). The signal is amplified by silver nanotags on the DNA duplex. The assay mainly consists of capture probe, detection probe, and two different DNA hairpins. In the presence of target DNA, the capture probe immobilized on the sensor sandwiches target DNA with the 3' end of detection probe. Another exposed part of detection probe at the 5' end opens two alternating DNA hairpins in turn, and propagates a chain reaction of hybridization events to form a nicked double-helix. Finally, numerous silver nanotags are immobilized onto the long-range DNA nanostructures, each of which produces a strong electronic signal within the applied potentials. Under optimal conditions, the target-triggered long-range DNA nanostructures present good electrochemical behaviors for the detection of HIV DNA at a concentration as low as 0.5 fM. Importantly, the outstanding sensitivity can make this approach a promising scheme for development of next-generation DNA sensors without the need of enzyme labeling or fluorophore labeling. PMID:23726095

  3. Rapid hybridization of nucleic acids using isotachophoresis

    E-print Network

    Santiago, Juan G.

    Rapid hybridization of nucleic acids using isotachophoresis Moran Bercovicia,b,1,2 , Crystal M of nucleic acid hybridization reactions in free solution. We present a new physical model, validation are generally applicable to acceleration of reactions invol- ving nucleic acids, and may be applicable to a wide

  4. Optimizing the specificity of nucleic acid hybridization

    Microsoft Academic Search

    Sherry Xi Chen; David Yu Zhang; Peng Yin

    2012-01-01

    The specific hybridization of complementary sequences is an essential property of nucleic acids, enabling diverse biological and biotechnological reactions and functions. However, the specificity of nucleic acid hybridization is compromised for long strands, except near the melting temperature. Here, we analytically derived the thermodynamic properties of a hybridization probe that would enable near-optimal single-base discrimination and perform robustly across diverse

  5. Electrostatic nucleic Acid nanoassembly enables hybridization chain reaction in living cells for ultrasensitive mRNA imaging.

    PubMed

    Wu, Zhan; Liu, Gao-Qin; Yang, Xiao-Li; Jiang, Jian-Hui

    2015-06-01

    Efficient approaches for intracellular delivery of nucleic acid reagents to achieve sensitive detection and regulation of gene and protein expressions are essential for chemistry and biology. We develop a novel electrostatic DNA nanoassembly that, for the first time, realizes hybridization chain reaction (HCR), a target-initiated alternating hybridization reaction between two hairpin probes, for signal amplification in living cells. The DNA nanoassembly has a designed structure with a core gold nanoparticle, a cationic peptide interlayer, and an electrostatically assembled outer layer of fluorophore-labeled hairpin DNA probes. It is shown to have high efficiency for cellular delivery of DNA probes via a unique endocytosis-independent mechanism that confers a significant advantage of overcoming endosomal entrapment. Moreover, electrostatic assembly of DNA probes enables target-initialized release of the probes from the nanoassembly via HCR. This intracellular HCR offers efficient signal amplification and enables ultrasensitive fluorescence activation imaging of mRNA expression with a picomolar detection limit. The results imply that the developed nanoassembly may provide an invaluable platform in low-abundance biomarker discovery and regulation for cell biology and theranostics. PMID:25969953

  6. Microwave (MW) irradiated Ugi four-component reaction (Ugi-4CR): Expedited synthesis of steroid-amino acid conjugates - A novel class of hybrid compounds.

    PubMed

    Borah, Preetismita; Borah, Juri Moni; Chowdhury, Pritish

    2015-06-01

    Microwave (MW) assisted chemical reactions are currently gaining considerable importance in organic synthesis to contribute in green technology. Considering the importance of peptidomimetic steroid-amino acid conjugates - a novel class of hybrid compounds having diverse biological properties, we report here synthesis of these compounds of alanine and valine methyl esters with seco-steroids (A, B and D ring cleavage) in expedited way by MW promoted Ugi-four-component reaction (Ugi-4CR). PMID:25701096

  7. Theory of hybrid nuclear reactions

    SciTech Connect

    Udagawa, T.

    1983-01-01

    A theory of hybrid nuclear reactions, which are partially direct and partially compound, is presented. We review first the formulation of the theory, based on the optical theorem, and then its applications to a few example reactions. Discussions will be given on the physical picture (deep peripheral nature) of such hybrid processes emerging from the numerical studies. 25 references, 10 figures.

  8. Rapid hybridization of nucleic acids using isotachophoresis

    PubMed Central

    Bercovici, Moran; Han, Crystal M.; Liao, Joseph C.; Santiago, Juan G.

    2012-01-01

    We use isotachophoresis (ITP) to control and increase the rate of nucleic acid hybridization reactions in free solution. We present a new physical model, validation experiments, and demonstrations of this assay. We studied the coupled physicochemical processes of preconcentration, mixing, and chemical reaction kinetics under ITP. Our experimentally validated model enables a closed form solution for ITP-aided reaction kinetics, and reveals a new characteristic time scale which correctly predicts order 10,000-fold speed-up of chemical reaction rate for order 100 pM reactants, and greater enhancement at lower concentrations. At 500 pM concentration, we measured a reaction time which is 14,000-fold lower than that predicted for standard second-order hybridization. The model and method are generally applicable to acceleration of reactions involving nucleic acids, and may be applicable to a wide range of reactions involving ionic reactants. PMID:22733732

  9. Triggered amplification by hybridization chain reaction

    E-print Network

    Pierce, Niles A.

    Triggered amplification by hybridization chain reaction Robert M. Dirks and Niles A. Pierce chain reaction (HCR), in which stable DNA monomers assemble only upon exposure to a target DNA fragment termed hybridization chain reaction (HCR). This class of mech- anisms suggests the possibility

  10. Optimizing the specificity of nucleic acid hybridization

    E-print Network

    Zhang, David Yu

    Optimizing the specificity of nucleic acid hybridization David Yu Zhang1,2 *, Sherry Xi Chen3, the specificity of nucleic acid hybridization is compromised for long strands, except near the melting temperature to 37 88888C, from 1 mM Mg21 to 47 mM Mg21 , and with nucleic acid concentrations from 1 nM to 5 m

  11. Reaction of citric acid with calcite

    Microsoft Academic Search

    M. H. Al-Khaldi; H. A. Nasr-El-Din; S. Mehta; A. D. Al-Aamri

    2007-01-01

    The reaction of citric acid with calcite was investigated using the rotating disk apparatus. The effects of disk rotational speed, system pressure, and presence of magnesium and ferric ions on this reaction were examined. Scanning electron microscope (SEM) was also used to characterize the surface of the calcite disks at the end of each experiment.The reaction of citric acid and

  12. Detection of nucleic acid hybrids by prolonged chemiluminescence

    SciTech Connect

    Dattagupta, N.; Clemens, A.H.

    1988-12-27

    A method for determining a particular single stranded polynucleotide sequence in a test medium, comprising the steps of: (a) immobilizing on a solid support single stranded nucleic acids in the test medium, (b) contacting the immobilized nucleic acids with a polynucleotide probe having a base sequence substantially complementary to the sequence to be determined and the contacting being under conditions favorable to hybridization between the probe and the sequence to be determined, wherein the probe is labeled with a chemiluminescence enhancer, (c) separating the immobilized hybrids from the unhybridized probe, (d) initiating a chemiluminescent reaction by contacting the separated, labeled, immobilized hybrids with an oxidant, a 2.3-dihydro-1,4-phthalazinedione chemiluminescence precursor, and a peroxidase enzyme, (e) detecting the resulting light emission, and (f) relating the amount of emitted light to the amount of the single stranded polynucleotide sequence.

  13. Dextran sulfate provides a quantitative and quick microarray hybridization reaction.

    PubMed

    Ku, Wei-Chi; Lau, Wai Kwan; Tseng, Yu-Tien; Tzeng, Chi-Meng; Chiu, Sung-Kay

    2004-02-27

    Microarray technology is a powerful tool to speed up genomics study, yet many technical aspects need to be improved. The hybridization reaction of microarray experiments is carried out for 16h or overnight in order to obtain reasonably strong signals for analysis in the presence of high salt buffer, like SSC. However, the quantitative aspect of microarray hybridization has seldom been investigated. In this study, we showed that higher overall signals from hybridization were achieved in a buffer system containing dextran sulfate, which can accelerate the kinetics of reaction by increasing the local concentration of the reactants. The dextran sulfate containing hybridization solution increases the reaction 4-fold (median) for cDNA microarray and 29-fold for oligonucleotide microarray. More importantly, the solution also provides a quantitative hybridization reaction, where the hybridization signals are proportional to the abundance of transcript added. The enhancement in the kinetics of hybridization is due to both dextran sulfate and formamide present in the solution, but the effect is not due to the higher temperature used during the reaction. With a slightly longer reaction time the hybridization reaction with the solution allows the detection of hybridization signals from rare transcripts that is not possible with regular hybridization buffers. With appropriate washing, the enhancement of kinetics by the solution does not increase the background signals at all, allowing higher signal-to-noise ratios to be achieved. PMID:15013421

  14. Heterogeneous Reactions of Epoxides in Acidic Media

    E-print Network

    Lal, Vinita

    2012-02-14

    Epoxides have been recently identified as one of the intermediate species in the gas phase oxidation of alkenes. This study investigates the reaction of isoprene oxide and alpha-pinene oxide with sulfuric acid to identify the potential of epoxides...

  15. SOIL REACTION AND ACIDIC DEPOSITION

    EPA Science Inventory

    This chapter discusses the major chemical processes by which acidic deposition interacts with soils. he focus is on forest soils, as the effects of acidic deposition on soils used for production of food and fiber are generally small compared to effects of agricultural practices s...

  16. Nonenzymatic catalytic signal amplification for nucleic acid hybridization assays

    NASA Technical Reports Server (NTRS)

    Fan, Wenhong (Inventor); Cassell, Alan M. (Inventor); Han, Jie (Inventor)

    2006-01-01

    Devices, methods, and kits for amplifying the signal from hybridization reactions between nucleic acid probes and their cognate targets are presented. The devices provide partially-duplexed, immobilized probe complexes, spatially separate from and separately addressable from immobilized docking strands. Cognate target acts catalytically to transfer probe from the site of probe complex immobilization to the site of immobilized docking strand, generating a detectable signal. The methods and kits of the present invention may be used to identify the presence of cognate target in a fluid sample.

  17. Catalytic performance of hybrid nanocatalyst for levulinic acid production from glucose

    NASA Astrophysics Data System (ADS)

    Ya'aini, Nazlina; Amin, Nor Aishah Saidina

    2012-11-01

    Levulinic acid is one of the potential and versatile biomass-derived chemicals. Product analysis via HPLC revealed that the heterogeneous dehydration of glucose over hybrid nanocatalyst exhibited better performance compared to single catalyst. Hybrid nanocatalyst containing H-Y zeolite and CrCl3 could substitute homogenous acid catalyst for attaining high levulinic acid yield. Different CrC3 and H-Y zeolite weight ratios of 1:1, 1:2 and 2:1 were prepared according to the wetness impregnation method. The hybrid catalyst with a 1:1 weight ratio performed better compared to others with the highest levulinic acid yield reported (93.5%) at 140 °C, 180 min reaction time, 0.1 g catalyst loading and 0.1 g glucose feed. Characterization results revealed that properties such as surface area, mesoporosity and acidic strength of the catalyst have significant effects on glucose dehydration for levulinic acid production.

  18. Hybridization and sequencing of nucleic acids using base pair mismatches

    SciTech Connect

    Fodor, Stephen P. A. (Palo Alto, CA); Lipshutz, Robert J. (Palo Alto, CA); Huang, Xiaohua (Mt. View, CA)

    2001-01-01

    Devices and techniques for hybridization of nucleic acids and for determining the sequence of nucleic acids. Arrays of nucleic acids are formed by techniques, preferably high resolution, light-directed techniques. Positions of hybridization of a target nucleic acid are determined by, e.g., epifluorescence microscopy. Devices and techniques are proposed to determine the sequence of a target nucleic acid more efficiently and more quickly through such synthesis and detection techniques.

  19. Gallic Acid, Ellagic Acid and Pyrogallol Reaction with Metallic Iron

    NASA Astrophysics Data System (ADS)

    Jaén, J. A.; González, L.; Vargas, A.; Olave, G.

    2003-06-01

    The reaction between gallic acid, ellagic acid and pyrogallol with metallic iron was studied using infrared and Mössbauer spectroscopy. Most hydrolysable tannins with interesting anticorrosive or inhibition properties are structurally related to these compounds, thus they may be used as models for the study of hydrolysable tannins and related polyphenols. The interaction was followed up to 3 months. Results indicated two different behaviors. At polyphenol concentrations higher than 1% iron converts to sparingly soluble and amorphous ferric (and ferrous) polyphenolate complexes. At lower concentrations (0.1%), the hydrolysis reactions are dominant, resulting in the formation of oxyhydroxides, which can be further reduced to compounds like magnetite by the polyphenols.

  20. Gallic Acid, Ellagic Acid and Pyrogallol Reaction with Metallic Iron

    Microsoft Academic Search

    J. A. Jaén; L. González; A. Vargas; G. Olave

    2003-01-01

    The reaction between gallic acid, ellagic acid and pyrogallol with metallic iron was studied using infrared and Mössbauer\\u000a spectroscopy. Most hydrolysable tannins with interesting anticorrosive or inhibition properties are structurally related to\\u000a these compounds, thus they may be used as models for the study of hydrolysable tannins and related polyphenols. The interaction\\u000a was followed up to 3 months. Results indicated

  1. 40 CFR 721.10679 - Carboxylic acid, substituted alkylstannylene ester, reaction products with inorganic acid tetra...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 2014-07-01 false Carboxylic acid, substituted alkylstannylene ester, reaction products with inorganic acid tetra alkyl ester (generic). 721...Substances § 721.10679 Carboxylic acid, substituted alkylstannylene...

  2. The chlorate-iodine-nitrous acid clock reaction.

    PubMed

    Sant'Anna, Rafaela T P; Faria, Roberto B

    2014-01-01

    A new clock reaction based on chlorate, iodine and nitrous acid is presented. The induction period of this new clock reaction decreases when the initial concentrations of chlorate, nitrous acid and perchloric acid increase, but it is independent on the initial iodine concentration. The proposed mechanism is based on the LLKE autocatalytic mechanism for the chlorite-iodide reaction and the initial reaction between chlorate and nitrous acid to produce nitrate and chlorite. This new clock reaction opens the possibility for a new family of oscillating reactions containing chlorate or nitrous acid, which in both cases has not been observed until now. PMID:25313803

  3. The Chlorate-Iodine-Nitrous Acid Clock Reaction

    PubMed Central

    Sant'Anna, Rafaela T. P.; Faria, Roberto B.

    2014-01-01

    A new clock reaction based on chlorate, iodine and nitrous acid is presented. The induction period of this new clock reaction decreases when the initial concentrations of chlorate, nitrous acid and perchloric acid increase, but it is independent on the initial iodine concentration. The proposed mechanism is based on the LLKE autocatalytic mechanism for the chlorite-iodide reaction and the initial reaction between chlorate and nitrous acid to produce nitrate and chlorite. This new clock reaction opens the possibility for a new family of oscillating reactions containing chlorate or nitrous acid, which in both cases has not been observed until now. PMID:25313803

  4. 40 CFR 721.10125 - Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 2014-07-01 false Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid alkyl ester (generic). 721.10125...Substances § 721.10125 Alkenedioic acid, dialkyl ester, reaction products...

  5. 40 CFR 721.10125 - Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 2012-07-01 false Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid alkyl ester (generic). 721.10125...Substances § 721.10125 Alkenedioic acid, dialkyl ester, reaction products...

  6. 40 CFR 721.10125 - Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 2013-07-01 false Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid alkyl ester (generic). 721.10125...Substances § 721.10125 Alkenedioic acid, dialkyl ester, reaction products...

  7. 40 CFR 721.10125 - Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 2010-07-01 false Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid alkyl ester (generic). 721.10125...Substances § 721.10125 Alkenedioic acid, dialkyl ester, reaction products...

  8. 40 CFR 721.10125 - Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 2011-07-01 false Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid alkyl ester (generic). 721.10125...Substances § 721.10125 Alkenedioic acid, dialkyl ester, reaction products...

  9. Synthesis and conformational analysis of hybrid ?/?-dipeptides incorporating S-glycosyl-?(2,2)-amino acids.

    PubMed

    García-González, Iván; Mata, Lara; Corzana, Francisco; Jiménez-Osés, Gonzalo; Avenoza, Alberto; Busto, Jesús H; Peregrina, Jesús M

    2015-01-12

    We synthesized and carried out the conformational analysis of several hybrid dipeptides consisting of an ?-amino acid attached to a quaternary glyco-?-amino acid. In particular, we combined a S-glycosylated ?(2,2)-amino acid and two different types of ?-amino acid, namely, aliphatic (alanine) and aromatic (phenylalanine and tryptophan) in the sequence of hybrid ?/?-dipeptides. The key step in the synthesis involved the ring-opening reaction of a chiral cyclic sulfamidate, inserted in the peptidic sequence, with a sulfur-containing nucleophile by using 1-thio-?-D-glucopyranose derivatives. This reaction of glycosylation occurred with inversion of configuration at the quaternary center. The conformational behavior in aqueous solution of the peptide backbone and the glycosidic linkage for all synthesized hybrid glycopeptides was analyzed by using a protocol that combined NMR experiments and molecular dynamics with time-averaged restraints (MD-tar). Interestingly, the presence of the sulfur heteroatom at the quaternary center of the ?-amino acid induced ? torsional angles close to 180° (anti). Notably, this value changed to 60° (gauche) when the peptidic sequence displayed aromatic ?-amino acids due to the presence of CH-? interactions between the phenyl or indole ring and the methyl groups of the ?-amino acid unit. PMID:25413453

  10. Proximity-dependent initiation of hybridization chain reaction

    PubMed Central

    Koos, Björn; Cane, Gaëlle; Grannas, Karin; Löf, Liza; Arngården, Linda; Heldin, Johan; Clausson, Carl-Magnus; Klaesson, Axel; Hirvonen, M. Karoliina; de Oliveira, Felipe M. S.; Talibov, Vladimir O.; Pham, Nhan T.; Auer, Manfred; Danielson, U. Helena; Haybaeck, Johannes; Kamali-Moghaddam, Masood; Söderberg, Ola

    2015-01-01

    Sensitive detection of protein interactions and post-translational modifications of native proteins is a challenge for research and diagnostic purposes. A method for this, which could be used in point-of-care devices and high-throughput screening, should be reliable, cost effective and robust. To achieve this, here we design a method (proxHCR) that combines the need for proximal binding with hybridization chain reaction (HCR) for signal amplification. When two oligonucleotide hairpins conjugated to antibodies bind in close proximity, they can be activated to reveal an initiator sequence. This starts a chain reaction of hybridization events between a pair of fluorophore-labelled oligonucleotide hairpins, generating a fluorescent product. In conclusion, we show the applicability of the proxHCR method for the detection of protein interactions and posttranslational modifications in microscopy and flow cytometry. As no enzymes are needed, proxHCR may be an inexpensive and robust alternative to proximity ligation assays. PMID:26065580

  11. Proximity-dependent initiation of hybridization chain reaction.

    PubMed

    Koos, Björn; Cane, Gaëlle; Grannas, Karin; Löf, Liza; Arngården, Linda; Heldin, Johan; Clausson, Carl-Magnus; Klaesson, Axel; Hirvonen, M Karoliina; de Oliveira, Felipe M S; Talibov, Vladimir O; Pham, Nhan T; Auer, Manfred; Danielson, U Helena; Haybaeck, Johannes; Kamali-Moghaddam, Masood; Söderberg, Ola

    2015-01-01

    Sensitive detection of protein interactions and post-translational modifications of native proteins is a challenge for research and diagnostic purposes. A method for this, which could be used in point-of-care devices and high-throughput screening, should be reliable, cost effective and robust. To achieve this, here we design a method (proxHCR) that combines the need for proximal binding with hybridization chain reaction (HCR) for signal amplification. When two oligonucleotide hairpins conjugated to antibodies bind in close proximity, they can be activated to reveal an initiator sequence. This starts a chain reaction of hybridization events between a pair of fluorophore-labelled oligonucleotide hairpins, generating a fluorescent product. In conclusion, we show the applicability of the proxHCR method for the detection of protein interactions and posttranslational modifications in microscopy and flow cytometry. As no enzymes are needed, proxHCR may be an inexpensive and robust alternative to proximity ligation assays. PMID:26065580

  12. Hybrid Multiscale Simulation of a Mixing-Controlled Reaction

    NASA Astrophysics Data System (ADS)

    Yang, X.; Scheibe, T. D.; Schuchardt, K.; Agarwal, K.; Chase, J.; Palmer, B. J.; Tartakovsky, A. M.; Elsethagen, T.

    2014-12-01

    Continuum scale models have been used to study subsurface flow, transport, and reactions for many years but lack the capability to resolve fine-grained processes. Recently, pore-scale models, which operate at scales of individual soil grains, have been developed to more accurately model and study pore-scale phenomena, such as mineral precipitation and dissolution reactions, microbially-mediated surface reactions, and other complex processes. However, these highly-resolved models are prohibitively expensive for modeling domains of sizes relevant to practical problems. To broaden the utility of pore-scale models for larger domains, we developed a hybrid multiscale model that initially simulates the full domain at the continuum scale and applies a pore-scale model only to areas of high reactivity. Python script components provide loose coupling between the pore- and continuum-scale codes into a single hybrid multiscale model implemented in the SWIFT parallel scripting language. We consider an irreversible homogenous bimolecular reaction (two solutes reacting to form a third solute) in a 2D test problem. This presentation is focused on the approach used for multiscale coupling between pore- and continuum-scale models, application to a realistic test problem, and implications of the results for predictive simulation of mixing-controlled reactions in porous media. Our results and analysis demonstrate that loose coupling provides a feasible, efficient and scalable approach for multiscale subsurface simulations.

  13. Multicomponent cascade reactions of unprotected carbohydrates and amino acids.

    PubMed

    Voigt, Benjamin; Linke, Michael; Mahrwald, Rainer

    2015-06-01

    Herein an operationally simple multicomponent reaction of unprotected carbohydrates with amino acids and isonitriles is presented. By the extension of this Ugi-type reaction to an unprotected disaccharide a novel glycopeptide structure was accessible. PMID:25952697

  14. Ugi reactions with trifunctional ?-amino acids, aldehydes, isocyanides and alcohols

    Microsoft Academic Search

    Ivar Ugi; Anton Demharter; Werner Hörl; Thomas Schmid

    1996-01-01

    1,1?-iminodicarboxylic acid derivatives, which are similar to many natural substances can be synthesized in excellent yields and with high stereoselectivity by a one-pot reaction of ?-amino acids, aldehydes, isocyanides and alcohols.

  15. Atmospheric Environment 40 (2006) 68636878 Acid-catalyzed reactions of hexanal on sulfuric acid particles

    E-print Network

    Elrod, Matthew J.

    2006-01-01

    Atmospheric Environment 40 (2006) 6863­6878 Acid-catalyzed reactions of hexanal on sulfuric acid are incorporated into atmospheric aerosols are not well understood. Acid-catalyzed reactions of compounds into acidic aerosols. In the present study, we use the aerodyne aerosol mass spectrometer (AMS) to probe

  16. Acid Components in Arachis Species and Interspecies Hybrids with High Oleic and Low Palmitic Acids

    Microsoft Academic Search

    Hui-Fang JIANG; Xiao-Ping REN; Jia-Quan HUANG; Yong LEI; Bo-Shou LIAO

    2009-01-01

    Fatty acids of 87 wild Arachis accessions and 113 interspecific hybrid derivatives were tested to investigate their variations and breeding potential for improving fatty acid content in cultivated peanut (A. hypogaea L.). Compared with cultivated peanut, the wild species showed similar palmitic content, lower stearic and oleic contents, and higher linoleic content. The components of fatty acids varied obviously across

  17. Fe x C–C hybrid material as a support for Pt anode catalyst in direct formic acid fuel cell

    Microsoft Academic Search

    Xiao-Ming Wang; Yong-Yao Xia

    2009-01-01

    FexC–C hybrid material as a support for Pt anode catalyst in direct formic acid fuel cell was investigated for the first time. The resultant Pt\\/FexC–C catalysts were prepared by using a simple reduction reaction to load Pt on FexC–C hybrid material, which was synthesized through the carbonization of sucrose and Fe(NO3)3. It was found that the Pt\\/FexC–C catalysts exhibited excellent

  18. Models for Multi-Specie Chemical Reactions Using Polynomial Stochastic Hybrid Systems

    E-print Network

    Hespanha, João Pedro

    Models for Multi-Specie Chemical Reactions Using Polynomial Stochastic Hybrid Systems Abhyudai for chemical reactions is presented. This is done by representing the population of various species involved in a chemical reaction as the continuous state of a polynomial Stochastic Hybrid System (pSHS). An important

  19. Polymerase Chain reaction generated probes for fluorescence in situ hybridization.

    PubMed

    Dupont, J M; Lebbar, A; Dupuy, O; Frydman, N; Letessier, D; Auvinet, P; Rabineau, D

    1998-01-01

    The extended use of Fish with centromeric probes in many cytogenetic laboratories is often impaired by the cost of this technique. Polymerase Chain Reaction (PCR) constitutes a simple way to generate and label such centromeric probes at low cost. Two types of human DNA source can be used: 1--Somatic hybrid cell lines containing a unique human chromosome. The specific amplification of the human subset of alphoid DNA is realised with a primer pair specific for the consensus region of human alpha satellite sequence. 2--Total Human DNA. This time, a primer pair specific for the alpha satellite DNA of the chromosome of interest must be designed. These probes, labelled during the PCR reaction by direct incorporation of modified dUTP, are actually widely used in our laboratory, alone or mixed with other probes (chromosome painting or locus specific probes). PMID:11928124

  20. Effect of inclusion complex on nitrous acid reaction with flavonoids

    NASA Astrophysics Data System (ADS)

    Khalafi, Lida; Rafiee, Mohammad; Sedaghat, Sajjad

    2011-10-01

    The kinetic of the nitrous acid reactions with quercetin and catechin has been studied using spectrophotometric method in aqueous solution. The results show that these antioxidants participate in oxidation reactions with nitrous acid which is derived from protonation of nitrite ion in mild acidic conditions. Corresponding o-quinones as relatively stable products were detected by spectrophotometric techniques. pH dependence of the reactions has been examined and the rate constants of reactions were obtained by non-linear fitting of kinetic profiles. The effect of ?-cyclodextrin on the oxidation pathway was another object of this study. It is shown that ?-cyclodextrin has an inhibitory effect on the oxidation reaction. The rate constants of oxidation reactions for complexed forms and their stability constants were obtained based on changes in the reaction rates as a function of ?-cyclodextrin concentration.

  1. A new fluorescence reaction for the detection of boric acid

    Microsoft Academic Search

    K. Neelakantam; L. Ramachandra Row

    1942-01-01

    Summary  A new fluorescence reaction for the detection of boric acid with resacetophenone and phosphoric acid has been described. None\\u000a of the metallic radicles examined interferes while among the acid radicles chromate, bromate, chlorate, nitrite and fluoride\\u000a do so to a limited extent. The reaction compares favourably with those described in the literature both as regards limit of\\u000a identification and also

  2. Mfold web server for nucleic acid folding and hybridization prediction

    Microsoft Academic Search

    Michael Zuker

    2003-01-01

    The abbreviated name,'mfold web server',describes a number of closely related software applications available on the World Wide Web (WWW) for the prediction of the secondary structure of single stranded nucleic acids. The objective of this web server is to provide easy access to RNA and DNA folding and hybridization software to the scientific community at large. By making use of

  3. Photoinitiator Nucleotide for Quantifying Nucleic Acid Hybridization

    PubMed Central

    Johnson, Leah M.; Hansen, Ryan R.; Urban, Milan; Kuchta, Robert D.; Bowman, Christopher N.

    2010-01-01

    This first report of a photoinitiator-nucleotide conjugate demonstrates a novel approach for sensitive, rapid and visual detection of DNA hybridization events. This approach holds potential for various DNA labeling schemes and for applications benefiting from selective DNA-based polymerization initiators. Here, we demonstrate covalent, enzymatic incorporation of an eosin-photoinitiator 2?-deoxyuridine-5?-triphosphate (EITC-dUTP) conjugate into surface-immobilized DNA hybrids. Subsequent radical chain photoinitiation from these sites using an acrylamide/bis-acrylamide formulation yields a dynamic detection range between 500pM and 50nM of DNA target. Increasing EITC-nucleotide surface densities leads to an increase in surface-based polymer film heights until achieving a film height plateau of 280nm ±20nm at 610 ±70 EITC-nucleotides/?m2. Film heights of 10–20 nm were obtained from eosin surface densities of approximately 20 EITC-nucleotides/?m2 while below the detection limit of ~10 EITC-nucleotides/?m2, no detectable films were formed. This unique threshold behavior is utilized for instrument-free, visual quantification of target DNA concentration ranges. PMID:20337438

  4. Iminodicarboxylic acids in the Murchison meteorite: Evidence of Strecker reactions

    NASA Astrophysics Data System (ADS)

    Lerner, Narcinda R.; Cooper, George W.

    2005-06-01

    ?-Amino acids and ?-hydroxy acids are well known constituents of several carbonaceous meteorites. One proposed mechanism of their formation is the reactions of CN -, NH 3, aldehydes and ketones in aqueous solution, a Strecker-like synthesis. Iminodicarboxylic acids, relatively unusual in molecular structure, are significant by-products of laboratory Strecker syntheses of ?-amino acids. It is therefore notable that an analogous suite of imino acids has not been reported in CM2 chondrites where amino and hydroxy acids are abundant. In this work, aqueous extracts of the Murchison meteorite were examined for the presence of imino acids; GC-MS and HPLC molecular analyses revealed a complex suite of such acids. With the exception of one of the seven-carbon members, all of the C4 through C7 imino acids were observed in Murchison. These observations suggest that the Strecker synthesis made, at least, some contribution to the formation of extraterrestrial amino acids.

  5. Nucleic acid hybridization with RNA immobilized on filter paper.

    NASA Technical Reports Server (NTRS)

    Saxinger, W. C.; Ponnamperuma, C.; Gillespie, D.

    1972-01-01

    RNA has been immobilized in a manner suitable for use in molecular hybridization experiments with dissolved RNA or DNA by a nonaqueous solid-phase reaction with carbonyldiimidazole and RNA 'dry coated' on cellulose or, preferably, on previously activated phosphocellulose filters. Immobilization of RNA does not appear to alter its chemical character or cause it to acquire affinity for unspecific RNA or DNA. The versatility and efficiency of this method make it potentially attractive for use in routine analytical or preparative hybridization experiments, among other applications.

  6. Accurate hybrid stochastic simulation of a system of coupled chemical or biochemical reactions

    E-print Network

    Minnesota, University of

    Accurate hybrid stochastic simulation of a system of coupled chemical or biochemical reactions reactions, approximates the fast reactions as a continuous Markov process, using a chemical Langevin multiple slow reactions may occur within a time step of the numerical integration of the chemical Langevin

  7. Synthesis and characterization of hybrid hyaluronic acid-gelatin hydrogels.

    PubMed

    Camci-Unal, Gulden; Cuttica, Davide; Annabi, Nasim; Demarchi, Danilo; Khademhosseini, Ali

    2013-04-01

    Biomimetic hybrid hydrogels have generated broad interest in tissue engineering and regenerative medicine. Hyaluronic acid (HA) and gelatin (hydrolyzed collagen) are naturally derived polymers and biodegradable under physiological conditions. Moreover, collagen and HA are major components of the extracellular matrix (ECM) in most of the tissues (e.g., cardiovascular, cartilage, neural). When used as a hybrid material, HA-gelatin hydrogels may enable mimicking the ECM of native tissues. Although HA-gelatin hybrid hydrogels are promising biomimetic substrates, their material properties have not been thoroughly characterized in the literature. Herein, we generated hybrid hydrogels with tunable physical and biological properties by using different concentrations of HA and gelatin. The physical properties of the fabricated hydrogels including swelling ratio, degradation, and mechanical properties were investigated. In addition, in vitro cellular responses in both two and three-dimensional culture conditions were assessed. It was found that the addition of gelatin methacrylate (GelMA) into HA methacrylate (HAMA) promoted cell spreading in the hybrid hydogels. Moreover, the hybrid hydrogels showed significantly improved mechanical properties compared to their single component analogs. The HAMA-GelMA hydrogels exhibited remarkable tunability behavior and may be useful for cardiovascular tissue engineering applications. PMID:23419055

  8. Oligomerization of Thioglutamic Acid: Encapsulated Reactions and Lipid Catalysis

    NASA Astrophysics Data System (ADS)

    Zepik, H. H.; Rajamani, S.; Maurel, M.-C.; Deamer, D.

    2007-12-01

    For cellular life to begin on the early Earth, a permeation mechanism would be required to allow polar solutes to enter a membrane-bounded compartment. A second process - internal polymerization of peptides from amino acid - would also be an essential step toward the first compartmented metabolic pathways leading to biosynthesis. Here we report a study of amino acid permeation into lipid vesicles, in which thioglutamic acid penetrated lipid bilayer membranes at rates sufficient to support internal polymerization reactions. We also investigated spontaneous non-enzymatic polymerization reactions of thioglutamic acid to form oligopeptides. We found that oligomers up to 11mers are produced in the reaction mixture, and conclude that certain lipid surfaces can act as catalysts in promoting an oligomerization reaction. These observations are pertinent to understanding processes by which peptide bond synthesis could take place in primitive cellular life on the early Earth.

  9. Nitro-fatty Acid Reaction with Glutathione and Cysteine

    PubMed Central

    Baker, Laura M. S.; Baker, Paul R. S.; Golin-Bisello, Franca; Schopfer, Francisco J.; Fink, Mitchell; Woodcock, Steven R.; Branchaud, Bruce P.; Radi, Rafael; Freeman, Bruce A.

    2007-01-01

    Fatty acid nitration by nitric oxide-derived species yields electrophilic products that adduct protein thiols, inducing changes in protein function and distribution. Nitro-fatty acid adducts of protein and reduced glutathione (GSH) are detected in healthy human blood. Kinetic and mass spectrometric analyses reveal that nitroalkene derivatives of oleic acid (OA-NO2) and linoleic acid (LNO2) rapidly react with GSH and Cys via Michael addition reaction. Rates of OA-NO2 and LNO2 reaction with GSH, determined via stopped flow spectrophotometry, displayed second-order rate constants of 183 M?1s?1 and 355 M?1s?1, respectively, at pH 7.4 and 37 °C. These reaction rates are significantly greater than those for GSH reaction with hydrogen peroxide and non-nitrated electrophilic fatty acids including 8-iso-prostaglandin A2 and 15-deoxy-?12,14-prostaglandin J2. Increasing reaction pH from 7.4 to 8.9 enhanced apparent second-order rate constants for the thiol reaction with OA-NO2 and LNO2, showing dependence on the thiolate anion of GSH for reactivity. Rates of nitroalkene reaction with thiols decreased as the pKa of target thiols increased. Increasing concentrations of the detergent octyl-?-D-glucopyranoside decreased rates of nitroalkene reaction with GSH, indicating that the organization of nitro-fatty acids into micellar or membrane structures can limit Michael reactivity with more polar nucleophilic targets. In aggregate, these results reveal that the reversible adduction of thiols by nitro-fatty acids is a mechanism for reversible post-translational regulation of protein function by nitro-fatty acids. PMID:17720974

  10. Reaction of Boric Acid with Polysaccharides

    Microsoft Academic Search

    H. Deuel; H. Neukom; F. Weber

    1948-01-01

    MANY polyhydroxy compounds of low molecular weight are known to form complexes with boric acid in aqueous solutions, as numerous investigations (Boeseken et al.) have shown. These complexes are much more easily obtained from cyclic glycols possessing the cis configuration than from the trans isomers. One boric acid molecule may react with either one or two 1,2-glycol molecules ; in

  11. 40 CFR 721.10629 - Fatty acids, tall-oil, reaction products with modified fatty acids and polyalkanolamines (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 2013-07-01 false Fatty acids, tall-oil, reaction products with modified fatty acids and polyalkanolamines (generic). 721...Chemical Substances § 721.10629 Fatty acids, tall-oil, reaction products with...

  12. 40 CFR 721.10629 - Fatty acids, tall-oil, reaction products with modified fatty acids and polyalkanolamines (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 2014-07-01 false Fatty acids, tall-oil, reaction products with modified fatty acids and polyalkanolamines (generic). 721...Chemical Substances § 721.10629 Fatty acids, tall-oil, reaction products with...

  13. Nucleophilic substitution reactions in 4-halonitro-pyrazolecarboxylic acids

    SciTech Connect

    Manaev, Yu.A.; Perevalov, V.P.; Andreeva, M.A.; Stepanov, B.I.

    1986-09-01

    The reaction of 4-bromo-1-methyl-3-nitropyrazole-5- and 4-bromo-1-methyl-5-nitro-pyrazole-3-carboxylic acids with arylamines in aqueous solution in the presence of monovalent copper salts leads to the formation of 4-arylamino- and 4-hydroxy substituted nitropyrazolecarboxylic acids.

  14. Heterogeneous Reactions of Epoxides in Acidic Media 

    E-print Network

    Lal, Vinita

    2012-02-14

    on sulfuric acid using Ion drift-Chemical Ionization Mass Spectrometry (ID-CIMS) showed an irreversible uptake of epoxides at room temperature resulting in the formation of less volatile products like diols, organosulfates and acetals. However, at lower...

  15. Marangoni instability in the iodate-arsenous acid reaction front

    NASA Astrophysics Data System (ADS)

    Pópity-Tóth, Éva; Pótári, Gábor; Erd?s, István; Horváth, Dezs?; Tóth, Ágota

    2014-07-01

    Horizontally propagating chemical fronts leading to the formation of a single stable convection roll are investigated in the iodate-arsenous acid reaction with arsenous acid stoichiometrically limiting, leaving the surface active iodine present in the product mixture. In sufficiently thin solution layers with open upper surface, the contribution of Marangoni instability is significantly enhanced. Acting in the same direction as buoyancy driven instability, it distorts the entire tilted reaction front that becomes 50% more elongated. The corresponding three-dimensional calculations based on the empirical rate-law of the reaction corroborate the experimental findings.

  16. Solid-state acid-base reactions of indomethacin and flufenamic acid

    Microsoft Academic Search

    Xiaoming Chen

    2000-01-01

    The purpose of this study is to understand the mechanism of solid-state acid-base reactions and identify controlling factors for this type of reaction. The reactions between indomethacin and sodium bicarbonate, indomethacin and sodium carbonate, and flufenamic acid and magnesium oxide were investigated using X-ray powder diffraction, Fourier transform infrared spectroscopy, thermogravimetry, and solid-state nuclear magnetic resonance spectrometry. Quantitative methods based

  17. Local Hybridization Chain-Reactions on the Surface of DNA Origami

    E-print Network

    Reif, John H.

    Local Hybridization Chain-Reactions on the Surface of DNA Origami Hieu Bui, * , Tianqi Song chain-reactions on the surface of a DNA origami rectangle 40 #12;A simple design of our localized to find the hairpins on the surface of DNA origami to trigger the reaction. An activated toehold domain

  18. Deoxyribonucleic Acid Base Composition and Hybridization Studies on the Human Pathogen Sporothrix schenckii and Ceratocystis Species

    PubMed Central

    Mendonça-Hagler, Leda C.; Travassos, L. R.; Lloyd, K. O.; Phaff, H. J.

    1974-01-01

    Deoxyribonucleic acid (DNA) base composition, as measured by guanine plus cytosine (G + C) content, was determined in 17 strains of Sporothrix schenckii and Ceratocystis species. The average G + C content for S. schenckii was 54.7 ± 0.2 mol%. No strain of Ceratocystis, with the exception of C. minor, gave values for G + C content similar to those obtained for S. schenckii. All DNA samples from strains of S. schenckii cross-hybridized with high percentages of relative binding. DNA samples from C. stenoceras and C. pilifera showed low degrees of homology with S. schenckii DNA. The DNA from C. minor hybridized with 75% binding with that from a strain of S. schenckii, as compared with the homologous reaction. PMID:4596280

  19. Reaction-diffusion travelling waves in the acidic nitrate-ferroin reaction

    Microsoft Academic Search

    J. H. Merkin; M. A. Sadiq

    1995-01-01

    A two-variable model proposed for the acidic nitrate-ferroin reaction is considered in the reaction-diffusion context. An initial-value problem in which an amount of nitrate is introduced locally into ferroin at uniform concentration is treated both analytically and numerically. It is shown that the large time structure is a reaction-diffusion travelling wave of permanent form propagating with constant speed. This asymptotic

  20. Kinetic-spectrophotometric determination of ascorbic acid by inhibition of the hydrochloric acid-bromate reaction

    NASA Astrophysics Data System (ADS)

    Ensafi, Ali A.; Rezaei, B.; Movahedinia, H.

    2002-10-01

    A new analytical method was developed for the determination of ascorbic acid in fruit juice and pharmaceuticals. The method is based on its inhibition effect on the reaction between hydrochloric acid and bromate. The decolourisation of Methyl Orange by the reaction products was used to monitor the reaction spectrophotometrically at 510 nm. The linearity range of the calibration graph depends on bromate concentration. The variable affecting the rate of the reaction was investigated. The method is simple, rapid, relatively sensitive and precise. The limit of detection is 7.6×10 -6 M and calibration rang is 8×10 -6-1.2×10 -3 M ascorbic acid. The relative standard deviation of seven replication determinations of 8×10 -6 and 2×10 -5 M ascorbic acid was 2.8 and 1.7%, respectively. The influence of potential interfering substance was studied. The method was successfully applied for the determination of ascorbic acid in pharmaceuticals.

  1. UNAFold: software for nucleic acid folding and hybridization.

    PubMed

    Markham, Nicholas R; Zuker, Michael

    2008-01-01

    The UNAFold software package is an integrated collection of programs that simulate folding, hybridization, and melting pathways for one or two single-stranded nucleic acid sequences. The name is derived from "Unified Nucleic Acid Folding." Folding (secondary structure) prediction for single-stranded RNA or DNA combines free energy minimization, partition function calculations and stochastic sampling. For melting simulations, the package computes entire melting profiles, not just melting temperatures. UV absorbance at 260 nm, heat capacity change (C(p)), and mole fractions of different molecular species are computed as a function of temperature. The package installs and runs on all Unix and Linux platforms that we have looked at, including Mac OS X. Images of secondary structures, hybridizations, and dot plots may be computed using common formats. Similarly, a variety of melting profile plots is created when appropriate. These latter plots include experimental results if they are provided. The package is "command line" driven. Underlying compiled programs may be used individually, or in special combinations through the use of a variety of Perl scripts. Users are encouraged to create their own scripts to supplement what comes with the package. This evolving software is available for download at http://www.bioinfo.rpi.edu/applications/hybrid/download.php . PMID:18712296

  2. 40 CFR 721.10126 - Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...triazine amino substituted benezenesulfonic acid reaction product with naphthalenesulfonato...phenyl azo substituted benzenesulfonic acid copper compound (generic). 721.10126...triazine amino substituted benezenesulfonic acid reaction product with...

  3. 40 CFR 721.10126 - Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...triazine amino substituted benezenesulfonic acid reaction product with naphthalenesulfonato...phenyl azo substituted benzenesulfonic acid copper compound (generic). 721.10126...triazine amino substituted benezenesulfonic acid reaction product with...

  4. Reaction mechanism for the acid ferric sulfate leaching of chalcopyrite

    Microsoft Academic Search

    P. B. Munoz; J. D. Miller; M. E. Wadsworth

    1979-01-01

    The acid ferric sulfate leaching of chalcopyrite, CuFeS2 + 4Fe+3 = Cu+2 + 5Fe+2 + 2S0 was studied using monosize particles in a well stirred reactor at ambient pressure and dilute solid phase concentration in\\u000a order to obtain fundamental details of the reaction kinetics. The principal rate limiting step for this electrochemical reaction\\u000a appears to be a transport process through

  5. Catalytical Conversion of Carbohydrates into Lactic Acid via Hydrothermal Reaction

    NASA Astrophysics Data System (ADS)

    Wei, Zhen; Jin, Fangming; Zhang, Guangyi; Zhang, Shiping; Yao, Guodong

    2010-11-01

    This paper focuses on catalytical conversion of carbohydrates into lactic acid, under the hydrothermal conditions, which may have a promising future for its high speediness and effectiveness. The catalysis of ZnO was investigated to improve the lactic acid yields. The results showed that the lactic acid yields increased immensely by the addition of ZnO. The effects of the reaction time and the addition amount of ZnO on the conversion of carbohydrates to lactic acid were studied. The highest lactic acid yields reached up to 28% starting from glucose after the reaction time of 60 s under the conditions of 0.2 mmol ZnO, 300° C, the filling rate of 35%, and over 30% starting from fructose at the same temperature and filling rate when the reaction time of 40 s and 2.0 mmol ZnO were employed. The collaborative effects of ZnO and NaOH used as the catalysts together at the same time were also studied. Furthermore, the catalytic mechanism of ZnO in the hydrothermal conversion of carbohydrates into lactic acid was discussed.

  6. 40 CFR 721.10664 - Alkenedioic acid dialkyl ester, reaction products with alkenoic acid alkyl esters and diamine...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...New Uses for Specific Chemical Substances § 721...acid dialkyl ester, reaction products with alkenoic...generic). (a) Chemical substances and significant...reporting. (1) The chemical substances identified...acid dialkyl ester, reaction products with...

  7. 40 CFR 721.10664 - Alkenedioic acid dialkyl ester, reaction products with alkenoic acid alkyl esters and diamine...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...New Uses for Specific Chemical Substances § 721...acid dialkyl ester, reaction products with alkenoic...generic). (a) Chemical substances and significant...reporting. (1) The chemical substances identified...acid dialkyl ester, reaction products with...

  8. Influence of secondary structure on kinetics and reaction mechanism of DNA hybridization

    Microsoft Academic Search

    Chunlai Chen; Wenjuan Wang; Zhang Wang; Fang Wei; Xin Sheng Zhao

    2007-01-01

    Hybridization of nucleic acids with secondary structure is involved in many biological processes and technological applications. To gain more insight into its mechanism, we have investigated the kinetics of DNA hybridization\\/denaturation via fluorescence resonance energy transfer (FRET) on perfectly matched and single-base-mismatched DNA strands. DNA hybridization shows non- Arrhenius behavior. At high temperature, the appar- ent activation energies of DNA

  9. Hybrid Lewis acid/hydrogen-bond donor receptor for fluoride.

    PubMed

    Hudnall, Todd W; Melaïmi, Mohand; Gabbaï, François P

    2006-06-22

    [reaction: see text] To verify if hydrogen-bond donor groups can assist fluoride binding at the boron center of triaryl boranes, o-(dimesitylboryl)trifluoroacetanilide has been synthesized. Reaction of this new borane with [n-Bu(4)N][F] in acetone affords the corresponding fluoroborate complex whose stability constant exceeds that of [Mes(3)BF](-) by at least 2 orders of magnitude. Presumably, the higher fluoride affinity of o-(dimesitylboryl)trifluoroacetanilide results from the cooperativity of the Lewis acidic boron center and the hydrogen-bond donor trifluoroacetamide group. PMID:16774247

  10. Mutagenicity and genotoxicity of sorbic acid-amine reaction products.

    PubMed

    Ferrand, C; Marc, F; Fritsch, P; Cassand, P; de Saint Blanquat, G

    2000-11-01

    Sorbic acid (E200) and its salts (potassium and calcium sorbate: E202 and E203) are allowed for use as preservatives in numerous processed foods. Sorbic acid had a conjugated system of double bonds which makes it susceptible to nucleophilic attack, sometimes giving mutagenic products. Under conditions typical of food processing (50-80 degrees C), we analysed the cyclic derivatives resulting from a double addition reaction between sorbic acid and various amines. Mutagenesis studies, involving Ames' test and genotoxicity studies with HeLa cells and plasmid DNA, showed that none of the products studied presented either mutagenic or genotoxic activities. PMID:11271702

  11. Structure-activity relationship of hybrids of Cinchona alkaloids and bile acids with in vitro antiplasmodial and antitrypanosomal activities.

    PubMed

    Leverrier, Aurélie; Bero, Joanne; Cabrera, Julián; Frédérich, Michel; Quetin-Leclercq, Joëlle; Palermo, Jorge A

    2015-07-15

    In this work, a series of hybrid compounds were tested as antiparasitic substances. These hybrids were prepared from bile acids and a series of antiparasitic Cinchona alkaloids by the formation of a covalent C-C bond via a decarboxylative Barton-Zard reaction between the two entities. The bile acids showed only weak antiparasitic properties, but all the hybrids exhibited high in vitro activities (IC50: 0.48-5.39 ?M) against Trypanosoma brucei. These hybrids were more active than their respective parent alkaloids (up to a 135 fold increase in activity), and displayed good selectivity indices. Aditionally, all these compounds inhibited the in vitro growth of a chloroquine-sensitive strain of Plasmodium falciparum (3D7: IC50: 36.1 nM to 8.72 ?M), and the most active hybrids had IC50s comparable to that of artemisinin (IC50: 36 nM). Some structure-activity relationships among the group of 48 hybrids are discussed. The increase in antiparasitic activity may be explained by an improvement in bioavailability, since the more lipophilic derivatives showed the lowest IC50s. PMID:26063305

  12. Radiochemical Reactions of Nucleic Acids and Nucleic Acid Components; STRAHLENCHEMISCHE REAKTIONEN VON NUCLEINSAURE UND NUCLEINSAUREKOMPONENTEN

    Microsoft Academic Search

    Weinblum

    1961-01-01

    The effects of ultraviolet radiation on nucleic acids were investigated. ; The problem, results, research on bacteria, stereoisomerism, sensitization, and ; the water addition reaction are discussed. X irradiation of pyrimidines was also ; studied using bacteria. Methionine was investigated as a radiation protection ; agent. The structure of adenine-1Noxide in bacteria desoxyribonucleic acid was ; determined. (M.C.G);

  13. Acid-catalyzed Heterogeneous Reactions in SOA Formation

    NASA Astrophysics Data System (ADS)

    Ng, N.; Keywood, M.; Varutbangkul, V.; Gao, S.; Loewer, E.; Surratt, J.; Richard, F. C.; John, S. H.

    2003-12-01

    The importance of heterogeneous reactions in secondary organic aerosol (SOA) formation has recently excited a great deal of interest in the aerosol community. Jang and Kamens (2001) showed enhanced aerosol yield from aldehydes, which can be produced by atmospheric photochemical reactions, in the presence of acidic seed. They suggest that the carbonyl functional groups of the aldehydes further react in the aerosol phase via hydration, polymerization, and hemiacetal/acetal formation with alcohols at an accelerated rate in the presence of acid. Jang et al. (2003) demonstrated similar results using a flow reactor and Czoschke et al. (in press) qualitatively showed increased yields for isoprene and alpha-pinene ozonolysis in the presence of acidic seed. While these findings are intriguing and important, the conditions under which the experiments were carried out were atmospherically unrealistic. A series of SOA formation experiments have been carried out in the Caltech Indoor Chamber Facility, which is comprised of dual 28 m3 FEP Teflon chambers, with the flexibility to carry out both dark ozonolysis and photochemical OH oxidation reactions. Cycloheptene and alpha-pinene were oxidized in the presence of neutral seed under dry (<10% RH) and humid (50% RH) conditions and in the presence of acidic seed under humid (50% RH) conditions. The SOA yields for these experiments will be presented, and the extent of the influence of acid-catalyzed reactions on SOA yield will be discussed. Reference List 1. Cocker, D. R. III. and R. C. Flagan and J. H. Seinfeld, State-of-the-art chamber facility for studying atmospheric aerosol chemistry, Environmental Science and Technology, 35, 2594-2601, 2001. 2. Czoschke, N. M., M. Jang, and R. M. Kamens, Effect of acid seed on biogenic sceondary organic aerosol growth, Atmospheric Environment, In press. 3. Jang, M., S. Lee, and R. M. Kamens, Organic aerosol growth by acid-catalyzed heterogeneous reactions of octanal in a flow reactor, Atmospheric Environment, 37, 2125-2138, 2003. 4. Jang, M. S. and R. M Kamens, Atmospheric secondary aerosol formation by heterogeneous reactions of aldehydes in the presence of a sulfuric acid aerosol catalyst. Environmental Science and Technology, 35, 4758-4766,2001.

  14. Template directed reactions of 2-aminoadenylic acid derivatives

    NASA Technical Reports Server (NTRS)

    Webb, T. R.; Orgel, L. E.

    1982-01-01

    The template-directed oligomerization of activated derivatives of 2-aminoadenylic acid (paA) on polyuridylic acid (poly(U)) in aqueous buffers was studied. The reaction differs from that of adenylic acid (pA) under identical conditions, in that only di- and tri-nucleotides are observed as substantial products rather than a longer sequence of oligomers. The reaction of paA also differs from that of pA in that it does not require Mg (2+), and is less susceptible to increased temperature. The relevance of these observations to the chemical evolution of polynucleotide replication is discussed. Improved syntheses of paA and its diphosphate are reported.

  15. Detection and isolation of nucleic acid sequences using competitive hybridization probes

    DOEpatents

    Lucas, J.N.; Straume, T.; Bogen, K.T.

    1997-04-01

    A method for detecting a target nucleic acid sequence in a sample is provided using hybridization probes which competitively hybridize to a target nucleic acid. According to the method, a target nucleic acid sequence is hybridized to first and second hybridization probes which are complementary to overlapping portions of the target nucleic acid sequence, the first hybridization probe including a first complexing agent capable of forming a binding pair with a second complexing agent and the second hybridization probe including a detectable marker. The first complexing agent attached to the first hybridization probe is contacted with a second complexing agent, the second complexing agent being attached to a solid support such that when the first and second complexing agents are attached, target nucleic acid sequences hybridized to the first hybridization probe become immobilized on to the solid support. The immobilized target nucleic acids are then separated and detected by detecting the detectable marker attached to the second hybridization probe. A kit for performing the method is also provided. 7 figs.

  16. Polymerase chain reaction system using magnetic beads for analyzing a sample that includes nucleic acid

    DOEpatents

    Nasarabadi, Shanavaz (Livermore, CA)

    2011-01-11

    A polymerase chain reaction system for analyzing a sample containing nucleic acid includes providing magnetic beads; providing a flow channel having a polymerase chain reaction chamber, a pre polymerase chain reaction magnet position adjacent the polymerase chain reaction chamber, and a post pre polymerase magnet position adjacent the polymerase chain reaction chamber. The nucleic acid is bound to the magnetic beads. The magnetic beads with the nucleic acid flow to the pre polymerase chain reaction magnet position in the flow channel. The magnetic beads and the nucleic acid are washed with ethanol. The nucleic acid in the polymerase chain reaction chamber is amplified. The magnetic beads and the nucleic acid are separated into a waste stream containing the magnetic beads and a post polymerase chain reaction mix containing the nucleic acid. The reaction mix containing the nucleic acid flows to an analysis unit in the channel for analysis.

  17. Modeling the Response of Fatty Acid Composition to Temperature in a Traditional Sunflower Hybrid

    Microsoft Academic Search

    Natalia G. Izquierdo; Luis A. N. Aguirrezábal; Fernando H. Andrade; Marcelo G. Cantarero

    2006-01-01

    Oil quality highly depends on its fatty acid composition. In tradi- tional sunflower (Helianthus annuus L.) hybrids, fatty acid composi- tion is affected by night temperature during grain filling. It is unknown if the increase of oleic acid concentration when night temperature increases saturates at a temperature threshold. Modeling the response of fatty acid composition to temperature could lead to

  18. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Uses for Specific Chemical Substances § 721...Hydrofluoric acid, reaction products with heptane. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products...

  19. 40 CFR 721.9460 - Tall oil fatty acids, reaction products with polyamines, alkyl substituted.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...New Uses for Specific Chemical Substances § 721...Tall oil fatty acids, reaction products with polyamines...substituted. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...tall oil fatty acids, reaction products with...

  20. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products with...

  1. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products with...

  2. 40 CFR 721.10464 - Fatty acid, reaction products with alkanolamine (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...New Uses for Specific Chemical Substances § 721.10464 Fatty acid, reaction products with alkanolamine (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified generically as fatty acid, reaction products with...

  3. 40 CFR 721.9460 - Tall oil fatty acids, reaction products with polyamines, alkyl substituted.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...New Uses for Specific Chemical Substances § 721...Tall oil fatty acids, reaction products with polyamines...substituted. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...tall oil fatty acids, reaction products with...

  4. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Uses for Specific Chemical Substances § 721...Hydrofluoric acid, reaction products with heptane. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products...

  5. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products with...

  6. 40 CFR 721.9460 - Tall oil fatty acids, reaction products with polyamines, alkyl substituted.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...New Uses for Specific Chemical Substances § 721...Tall oil fatty acids, reaction products with polyamines...substituted. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...tall oil fatty acids, reaction products with...

  7. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Uses for Specific Chemical Substances § 721...Hydrofluoric acid, reaction products with heptane. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products...

  8. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products with...

  9. 40 CFR 721.10251 - Fatty acids, reaction products with alkanolamine (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...New Uses for Specific Chemical Substances § 721.10251 Fatty acids, reaction products with alkanolamine (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...generically as fatty acids, reaction products with...

  10. 40 CFR 721.10464 - Fatty acid, reaction products with alkanolamine (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...New Uses for Specific Chemical Substances § 721.10464 Fatty acid, reaction products with alkanolamine (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified generically as fatty acid, reaction products with...

  11. 40 CFR 721.9460 - Tall oil fatty acids, reaction products with polyamines, alkyl substituted.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...New Uses for Specific Chemical Substances § 721...Tall oil fatty acids, reaction products with polyamines...substituted. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...tall oil fatty acids, reaction products with...

  12. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Uses for Specific Chemical Substances § 721...Hydrofluoric acid, reaction products with heptane. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products...

  13. 40 CFR 721.9460 - Tall oil fatty acids, reaction products with polyamines, alkyl substituted.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...New Uses for Specific Chemical Substances § 721...Tall oil fatty acids, reaction products with polyamines...substituted. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...tall oil fatty acids, reaction products with...

  14. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products with...

  15. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Uses for Specific Chemical Substances § 721...Hydrofluoric acid, reaction products with heptane. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydrofluoric acid, reaction products...

  16. 40 CFR 721.10251 - Fatty acids, reaction products with alkanolamine (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...New Uses for Specific Chemical Substances § 721.10251 Fatty acids, reaction products with alkanolamine (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...generically as fatty acids, reaction products with...

  17. 40 CFR 721.10251 - Fatty acids, reaction products with alkanolamine (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...New Uses for Specific Chemical Substances § 721.10251 Fatty acids, reaction products with alkanolamine (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...generically as fatty acids, reaction products with...

  18. Injectable in situ forming hybrid iron oxide-hyaluronic acid hydrogel for magnetic resonance imaging and drug delivery.

    PubMed

    Zhang, Yu; Sun, Yi; Yang, Xia; Hilborn, Jöns; Heerschap, Arend; Ossipov, Dmitri A

    2014-09-01

    The development of multimodal in situ cross-linkable hyaluronic acid nanogels hybridized with iron oxide nanoparticles is reported. Utilizing a chemoselective hydrazone coupling reaction, the nanogels are converted to a macroscopic hybrid hydrogel without any additional reagent. Hydrophobic cargos remain encapsulated in the hydrophobic domains of the hybrid hydrogel without leakage. However, hydrogel degradation with hyaluronidase liberates iron oxide nanoparticles. This allows the utilization of imaging agents as tracers of the hydrogel degradation. UV-vis spectrometry and MRI studies reveal that the degradability of the hydrogels correlates with their structure. The hydrogels presented here are very promising theranostic tools for hyaluronidase-mediated delivery of hydrophobic drugs, as well as imaging of hydrogel degradation and tracking of degradation products in vivo. PMID:24863175

  19. An amplified electrochemical aptasensor based on hybridization chain reactions and catalysis of silver nanoclusters

    NASA Astrophysics Data System (ADS)

    Chen, Ling; Sha, Liang; Qiu, Yuwei; Wang, Guangfeng; Jiang, Hong; Zhang, Xiaojun

    2015-02-01

    In the present study, based on the mimic oxidase catalytic character of nucleic-acid-stabilized silver nanoclusters (DNA/AgNCs) and hybridization chain reactions for signal amplification, the fabrication of a label-free sensitive ``turn-on'' electrochemical aptasensor for the amplified determination of lysozyme was demonstrated. First, the designed DNA duplex was modified on the electrode. With the specific binding of the target, lysozyme and its aptamer, the lysozyme-binding DNA sequence was liberated, exposing the induced DNA sequence, which in turn triggered the formation of the supersandwich DNA structure. Because the cytosine-rich sequence was designed ingeniously on the DNA sequence, DNA/AgNCs were formed on the supersandwich DNA structure. The peroxidase-like character of DNA/AgNCs produced detectable electrochemical signals for the lysozyme aptasensor, which showed a satisfying sensitive detection of lysozyme with a low detection limit of 42 pM and a wide linear range of 10-10 M to 10-5 M.In the present study, based on the mimic oxidase catalytic character of nucleic-acid-stabilized silver nanoclusters (DNA/AgNCs) and hybridization chain reactions for signal amplification, the fabrication of a label-free sensitive ``turn-on'' electrochemical aptasensor for the amplified determination of lysozyme was demonstrated. First, the designed DNA duplex was modified on the electrode. With the specific binding of the target, lysozyme and its aptamer, the lysozyme-binding DNA sequence was liberated, exposing the induced DNA sequence, which in turn triggered the formation of the supersandwich DNA structure. Because the cytosine-rich sequence was designed ingeniously on the DNA sequence, DNA/AgNCs were formed on the supersandwich DNA structure. The peroxidase-like character of DNA/AgNCs produced detectable electrochemical signals for the lysozyme aptasensor, which showed a satisfying sensitive detection of lysozyme with a low detection limit of 42 pM and a wide linear range of 10-10 M to 10-5 M. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06664b

  20. Detection of naturally occurring enteroviruses in waters by reverse transcription, polymerase chain reaction, and hybridization.

    PubMed Central

    Kopecka, H; Dubrou, S; Prevot, J; Marechal, J; López-Pila, J M

    1993-01-01

    Comparison in virus-seeded mineral water of three detection methods for enteroviruses, direct hybridization, cell culture, and reverse transcription into cDNA followed by polymerase chain reaction and hybridization, showed that the last procedure was 10 to 1,000 times more sensitive than detection by cell culture and 10(5) to 10(7) times more sensitive than direct hybridization. The presence of naturally occurring enteroviruses was also demonstrated in activated sludge and in concentrated and non-concentrated surface water samples by reverse transcription-polymerase chain reaction-hybridization. However, in activated sludge and in concentrated surface waters, enzymatic amplification was sometimes inhibited by contaminants. Images PMID:7683857

  1. Heterogeneous Reaction of HO2 Radical with Dicarboxylic Acid Particles

    NASA Astrophysics Data System (ADS)

    Taketani, F.; Kanaya, Y.

    2010-12-01

    HOx(OH+ HO2) radical plays a central role in the tropospheric chemistry. Recently, the heterogeneous loss of HO2 by aerosol particles is a potentially important HOx sink in the troposphere suggested from observation study. However, there have been few studies for loss of HO2 by aerosols. In this study, we measured the HO2 uptake coefficients for four dicarboxylic acids (succinic acid, glutaric acid, adipic acid, and pimelic acid) aerosol particles under ambient conditions (760Torr and 296K) using an aerosol flow tube(AFT) coupled with a chemical conversion /laser-induced fluorescence(CC/LIF) technique. The CC/LIF technique enabled experiments to be performed at almost the same HO2 radical concentration as that in the atmosphere(-10^8 molecules/cm^3). In this system, the effect of the self-reaction of HO2 in the gas phase can be neglected. HO2 radicals were injected into the AFT through a vertically movable Pyrex tube. Injector position dependent profiles of LIF intensity were measured as a function of aerosol concentration at 30% and 70% of relative humilities (RH). Determined HO2 uptake coefficients by succinic acid, glutaric acid, adipic acid, and pimelic acid aerosol particles at 30% RH were 0.05 +/- 0.02, 0.07 +/- 0.03, 0.02 +/- 0.01, and 0.06 +/- 0.03, respectively, while the uptake coefficients by those particles at 70% RH were 0.13 +/- 0.05, 0.13 +/- 0.03, 0.06 +/- 0.01, and 0.11 +/- 0.03, respectively. These results suggest that compositions and relative humidity are significant to the HO2 uptake. We will discuss the potential HO2 loss processes.

  2. Non-Exponential Smoluchowski Dynamics in Fast Acid-Base Reaction

    E-print Network

    Agmon, Noam

    Non-Exponential Smoluchowski Dynamics in Fast Acid-Base Reaction Boiko Cohen and Dan Huppert SchoolVised Manuscript ReceiVed July 11, 2000 Acid-base reactions are among the most fundamental processes in chemistry. Numerous liquid-phase reactions are known to be acid- or base-catalyzed. In biology, the proton appears

  3. Highly Stereoselective Synthesis of Natural-Product-Like Hybrids by an Organocatalytic/Multicomponent Reaction Sequence.

    PubMed

    Echemendía, Radell; de La Torre, Alexander F; Monteiro, Julia L; Pila, Michel; Corrêa, Arlene G; Westermann, Bernhard; Rivera, Daniel G; Paixão, Márcio W

    2015-06-22

    In an endeavor to provide an efficient route to natural product hybrids, described herein is an efficient, highly stereoselective, one-pot process comprising an organocatalytic conjugate addition of 1,3-dicarbonyls to ?,?-unsaturated aldehydes followed by an intramolecular isocyanide-based multicomponent reaction. This approach enables the rapid assembly of complex natural product hybrids including up to four different molecular fragments, such as hydroquinolinone, chromene, piperidine, peptide, lipid, and glycoside moieties. The strategy combines the stereocontrol of organocatalysis with the diversity-generating character of multicomponent reactions, thus leading to structurally unique peptidomimetics integrating heterocyclic, lipidic, and sugar moieties. PMID:25967546

  4. The Effect of Hetrogeneous Reactions on Model Performance for Nitrous Acid

    EPA Science Inventory

    Recent studies suggest that emissions, heterogeneous reactions, and surface photolysis of adsorbed nitric acid may produce additional nitrous acid in the atmosphere. The effects of these sources on nitrous acid formation are evaluated using the Community Multiscale Air Quality m...

  5. Salicylic acid biosynthesis is enhanced and contributes to increased biotrophic pathogen resistance in Arabidopsis hybrids.

    PubMed

    Yang, Li; Li, Bosheng; Zheng, Xiao-Yu; Li, Jigang; Yang, Mei; Dong, Xinnian; He, Guangming; An, Chengcai; Deng, Xing Wang

    2015-01-01

    Heterosis, the phenotypic superiority of a hybrid over its parents, has been demonstrated for many traits in Arabidopsis thaliana, but its effect on defence remains largely unexplored. Here, we show that hybrids between some A. thaliana accessions show increased resistance to the biotrophic bacterial pathogen Pseudomonas syringae pv. tomato (Pst) DC3000. Comparisons of transcriptomes between these hybrids and their parents after inoculation reveal that several key salicylic acid (SA) biosynthesis genes are significantly upregulated in hybrids. Moreover, SA levels are higher in hybrids than in either parent. Increased resistance to Pst DC3000 is significantly compromised in hybrids of pad4 mutants in which the SA biosynthesis pathway is blocked. Finally, increased histone H3 acetylation of key SA biosynthesis genes correlates with their upregulation in infected hybrids. Our data demonstrate that enhanced activation of SA biosynthesis in A. thaliana hybrids may contribute to their increased resistance to a biotrophic bacterial pathogen. PMID:26065719

  6. Salicylic acid biosynthesis is enhanced and contributes to increased biotrophic pathogen resistance in Arabidopsis hybrids

    PubMed Central

    Yang, Li; Li, Bosheng; Zheng, Xiao-yu; Li, Jigang; Yang, Mei; Dong, Xinnian; He, Guangming; An, Chengcai; Deng, Xing Wang

    2015-01-01

    Heterosis, the phenotypic superiority of a hybrid over its parents, has been demonstrated for many traits in Arabidopsis thaliana, but its effect on defence remains largely unexplored. Here, we show that hybrids between some A. thaliana accessions show increased resistance to the biotrophic bacterial pathogen Pseudomonas syringae pv. tomato (Pst) DC3000. Comparisons of transcriptomes between these hybrids and their parents after inoculation reveal that several key salicylic acid (SA) biosynthesis genes are significantly upregulated in hybrids. Moreover, SA levels are higher in hybrids than in either parent. Increased resistance to Pst DC3000 is significantly compromised in hybrids of pad4 mutants in which the SA biosynthesis pathway is blocked. Finally, increased histone H3 acetylation of key SA biosynthesis genes correlates with their upregulation in infected hybrids. Our data demonstrate that enhanced activation of SA biosynthesis in A. thaliana hybrids may contribute to their increased resistance to a biotrophic bacterial pathogen. PMID:26065719

  7. Catalytic effect of water, formic acid, or sulfuric acid on the reaction of formaldehyde with OH radicals.

    PubMed

    Zhang, Weichao; Du, Benni; Qin, Zhenglong

    2014-07-01

    In this paper, for the hydrogen abstraction reaction of HCHO by OH radicals assisted by water, formic acid, or sulfur acid, the possible reaction mechanisms and kinetics have been investigated theoretically using quantum chemistry methods and transition-state theory. The potential energy surfaces calculated at the CCSD(T)/6-311++G(df,pd)//MP2(full)/6-311++G(df,pd) levels of theory reveal that, due to the formation of strong hydrogen bond(s), the relative energies of the transition states involving catalyst are significantly reduced compared to that reaction without catalyst. However, the kinetics calculations show that the rate constants are smaller by about 3, 9, or 10 orders of magnitude for water, formic acid, or sulfur acid assisted reactions than that uncatalyzed reaction, respectively. Consequently, none of the water, formic acid, or sulfur acid can accelerate the title reaction in the atmosphere. PMID:24927334

  8. On the chemical reaction between carboxylic acids and iron, including the special case of naphthenic acid

    Microsoft Academic Search

    Omar Yépez

    2007-01-01

    The reaction between different carboxylic acids and iron was performed by monitoring the amount of iron dissolved in oil through the formation of the iron carboxylate and by the product distribution in the gas phase. It was found that the solubility of the given iron carboxylate strongly influences the concentration of iron dissolved in oil. At temperatures higher than 300°C,

  9. Fluorescent hybridization probes for nucleic acid detection Jia Guo & Jingyue Ju & Nicholas J. Turro

    E-print Network

    Turro, Nicholas J.

    REVIEW Fluorescent hybridization probes for nucleic acid detection Jia Guo & Jingyue Ju & Nicholas widely used to detect nucleic acids both in vivo and in vitro. Molecular beacons (MBs) and binary probes of identifying nucleic acid sequences are critical to biomedical research, disease diagnosis, and drug discovery

  10. A hybrid of holey graphene and Mn3O4 and its oxygen reduction reaction performance.

    PubMed

    Lv, Xiaohui; Lv, Wei; Wei, Wei; Zheng, Xiaoyu; Zhang, Chen; Zhi, Linjie; Yang, Quan-Hong

    2015-03-01

    A hybrid of holey graphene and Mn3O4 is prepared by a one-step process, in which the formation of a holey structure is accompanied with Mn3O4 nanoparticles through a high temperature reaction between graphene oxide sheets and KMnO4. Holey graphene and Mn3O4 collaboratively attributed to the enhanced catalytic activity and efficiency towards the oxygen reduction reaction. PMID:25656541

  11. Kinetics of the reaction of hydroxyl radicals with nitric acid

    NASA Technical Reports Server (NTRS)

    Margitan, J. J.; Watson, R. T.

    1982-01-01

    An extensive study was made of the reaction of hydroxyl radicals with nitric acid in a laser photolysis-resonance fluorescence system. A 266 nm laser was used to photolyze HNO3 in the temperature range 225-415 K at pressures of 20-300 torr. A temperature dependence was detected below room temperature, with a leveling off at 298 K and a wide spread in the rate constants. A pressure dependence was observed over the entire range and was more pronounced at lower temperatures. The results are noted to be in agreement with those of previous investigations. However, the wide range of rate constants are suggested to be a problem for stratospheric HO(x) modeling for anthropogenic effects. No explanation could be given of the varying results obtained by other investigators regarding the kinetics of the reactions.

  12. Formic acid production from carbohydrates biomass by hydrothermal reaction

    NASA Astrophysics Data System (ADS)

    Yun, J.; Jin, F.; Kishita, A.; Tohji, K.; Enomoto, H.

    2010-03-01

    The formation of formic acid or formate salts by hydrothermal oxidation of model biomass materials (glucose, starch and cellulose) was investigated. All experiments were conducted in a batch reactor, made of SUS 316 tubing, providing an internal volume of 5.7 cm3. A 30 wt% hydrogen peroxide aqueous solution was used as an oxidant. The experiments were carried out with temperature of 250°C, reaction time varying from 0.5 min to 5 min, H2O2 supply of 240%, and alkaline concentration varying from 0 to 1.25 M. Similar to glucose, in the cases of the oxidation of hydrothermal starch and cellulose, the addition of alkaline can also improve the yield of formic acid. And the yield were glucose>starch> cellulose in cases of with or without of alkaline addition.

  13. The nitric acid oxidation of 2-octanol. A model reaction for multiple heterogeneous liquid–liquid reactions

    Microsoft Academic Search

    B. A. A. van Woezik; K. R. Westerterp

    2000-01-01

    The oxidation of 2-octanol with nitric acid has been selected as a model reaction for a heterogeneous liquid–liquid reaction with an undesired side reaction. 2-Octanol is first oxidized to 2-octanone, which can be further oxidized to carboxylic acids. An extensive experimental program has been followed using heat flow calorimetry supported by chemical analysis. A series of oxidation experiments has been

  14. Nucleic acid amplification: Alternative methods of polymerase chain reaction

    PubMed Central

    Fakruddin, Md; Mannan, Khanjada Shahnewaj Bin; Chowdhury, Abhijit; Mazumdar, Reaz Mohammad; Hossain, Md. Nur; Islam, Sumaiya; Chowdhury, Md. Alimuddin

    2013-01-01

    Nucleic acid amplification is a valuable molecular tool not only in basic research but also in application oriented fields, such as clinical medicine development, infectious diseases diagnosis, gene cloning and industrial quality control. A comperehensive review of the literature on the principles, applications, challenges and prospects of different alternative methods of polymerase chain reaction (PCR) was performed. PCR was the first nucleic acid amplification method. With the advancement of research, a no of alternative nucleic acid amplification methods has been developed such as loop mediated isothermal amplification, nucleic acid sequence based amplification, strand displacement amplification, multiple displacement amplification. Most of the alternative methods are isothermal obviating the need for thermal cyclers. Though principles of most of the alternate methods are relatively complex than that of PCR, they offer better applicability and sensitivity in cases where PCR has limitations. Most of the alternate methods still have to prove themselves through extensive validation studies and are not available in commercial form; they pose the potentiality to be used as replacements of PCR. Continuous research is going on in different parts of the world to make these methods viable technically and economically. PMID:24302831

  15. Meta-DNA: Synthetic Biology via DNA Nanostructures and Hybridization Reactions

    E-print Network

    Reif, John H.

    Meta-DNA: Synthetic Biology via DNA Nanostructures and Hybridization Reactions Harish Chandran for desired functionality. The approach of this paper is to develop a biochemical system which we call meta-DNA (abbreviated as mDNA), based entirely on strands of DNA as the only component molecule. Our work leverages

  16. Enzymatic hybridization of ?-lipoic acid with bioactive compounds in ionic solvents.

    PubMed

    Papadopoulou, Athena A; Katsoura, Maria H; Chatzikonstantinou, Alexandra; Kyriakou, Eleni; Polydera, Angeliki C; Tzakos, Andreas G; Stamatis, Haralambos

    2013-05-01

    The lipase-catalyzed molecular hybridization of ?-lipoic acid (LA) with bioactive compounds pyridoxine, tyrosol and tyramine was performed in ionic solvents and deep eutectic solvents. The biocatalytic reactions were catalyzed by Candida antarctica lipase B immobilized onto various functionalized multi-walled carbon nanotubes (f-CNTs-CaLB), as well as by commercial Novozym 435. The use of f-CNTs-CaLB leads, in most cases, to higher conversion yields as compared to Novozym 435. The nature and ion composition of ionic solvents affect the performance of the biocatalytic process. The highest conversion yield was observed in (mtoa)NTf2. The high enzyme stability and the relatively low solubility of substrates in specific media account for the improved biocatalytic synthesis of molecular hybrids of LA. Principal component analysis was used to screen for potential lipoxygenase inhibitors. In vitro studies showed that the synthesized compounds exhibit up to 10-fold increased inhibitory activity on lipoxygenase mediated lipid peroxidation as compared to parent molecules. PMID:23567667

  17. Surface reactions of iron - enriched smectites: adsorption and transformation of hydroxy fatty acids and phenolic acids

    NASA Astrophysics Data System (ADS)

    Polubesova, Tamara; Olshansky, Yaniv; Eldad, Shay; Chefetz, Benny

    2014-05-01

    Iron-enriched smectites play an important role in adsorption and transformation of soil organic components. Soil organo-clay complexes, and in particular humin contain hydroxy fatty acids, which are derived from plant biopolymer cutin. Phenolic acids belong to another major group of organic acids detected in soil. They participate in various soil processes, and are of concern due to their allelopathic activity. We studied the reactivity of iron-enriched smectites (Fe(III)-montmorillonite and nontronite) toward both groups of acids. We used fatty acids- 9(10),16-dihydroxypalmitic acid (diHPA), isolated from curtin, and 9,10,16-trihydroxypalmitic acid (triHPA); the following phenolic acids were used: ferulic, p-coumaric, syringic, and vanillic. Adsorption of both groups of acids was measured. The FTIR spectra of fatty acid-mineral complexes indicated inner-sphere complexation of fatty acids with iron-enriched smectites (versus outer-sphere complexation with Ca(II)-montmorillonite). The LC-MS results demonstrated enhanced esterification of fatty acids on the iron-enriched smectite surfaces (as compared to Ca(II)-montmorillonite). This study suggests that fatty acids can be esterified on the iron-enriched smectite surfaces, which results in the formation of stable organo-mineral complexes. These complexes may serve as a model for the study of natural soil organo-clay complexes and humin. The reaction of phenolic acids with Fe(III)-montmorillonite demonstrated their oxidative transformation by the mineral surfaces, which was affected by molecular structure of acids. The following order of their transformation was obtained: ferulic >syringic >p-coumaric >vanillic. The LC-MS analysis demonstrated the presence of dimers, trimers, and tetramers of ferulic acid on the surface of Fe(III)-montmorillonite. Oxidation and transformation of ferulic acid were more intense on the surface of Fe(III)-montmorillonite as compared to Fe(III) in solution due to stronger complexation on the Fe(III)-motnomrillonite surface. Our study demonstrate the importance of iron-enriched minerals for the abiotic formation of humic materials and for the transformation of aromatic (phenolic) pollutants.

  18. Meta-DNA: synthetic biology via DNA nanostructures and hybridization reactions

    PubMed Central

    Chandran, Harish; Gopalkrishnan, Nikhil; Yurke, Bernard; Reif, John

    2012-01-01

    Can a wide range of complex biochemical behaviour arise from repeated applications of a highly reduced class of interactions? In particular, can the range of DNA manipulations achieved by protein enzymes be simulated via simple DNA hybridization chemistry? In this work, we develop a biochemical system which we call meta-DNA (abbreviated as mDNA), based on strands of DNA as the only component molecules. Various enzymatic manipulations of these mDNA molecules are simulated via toehold-mediated DNA strand displacement reactions. We provide a formal model to describe the required properties and operations of our mDNA, and show that our proposed DNA nanostructures and hybridization reactions provide these properties and functionality. Our meta-nucleotides are designed to form flexible linear assemblies (single-stranded mDNA (ssmDNA)) analogous to single-stranded DNA. We describe various isothermal hybridization reactions that manipulate our mDNA in powerful ways analogous to DNA–DNA reactions and the action of various enzymes on DNA. These operations on mDNA include (i) hybridization of ssmDNA into a double-stranded mDNA (dsmDNA) and heat denaturation of a dsmDNA into its component ssmDNA, (ii) strand displacement of one ssmDNA by another, (iii) restriction cuts on the backbones of ssmDNA and dsmDNA, (iv) polymerization reactions that extend ssmDNA on a template to form a complete dsmDNA, (v) synthesis of mDNA sequences via mDNA polymerase chain reaction, (vi) isothermal denaturation of a dsmDNA into its component ssmDNA, and (vii) an isothermal replicator reaction that exponentially amplifies ssmDNA strands and may be modified to allow for mutations. PMID:22237679

  19. Exploring ?-hydroxy ?-amino acids (statines) in the design of hybrid peptide foldamers.

    PubMed

    Bandyopadhyay, Anupam; Malik, Ankita; Kumar, Mothukuri Ganesh; Gopi, Hosahudya N

    2014-01-01

    The synthesis and characterization of syn and anti ?-hydroxy ?-amino acid (statine) diastereoisomers, their utilization in the design of hybrid peptide foldamers, and their single crystal conformations are studied. PMID:24320892

  20. Hybrid systems with lead–acid battery and proton-exchange membrane fuel cell

    Microsoft Academic Search

    Andreas Jossen; Juergen Garche; Harry Doering; Markus Goetz; Werner Knaupp; Ludwig Joerissen

    2005-01-01

    Hybrid systems, based on a lead–acid battery and a proton-exchange membrane fuel cell (PEMFC) give the possibility to combine the advantages of both technologies. The benefits for different applications are discussed and the practical realisation of such systems is shown. Furthermore a numerical model for such a hybrid system is described and results are shown and discussed. The results show

  1. Synthesis of high erucic acid rapeseed ( Brassica napus L.) somatic hybrids with improved agronomic characters

    Microsoft Academic Search

    D. W. Heath; E. D. Earle

    1995-01-01

    Novel Brassica napus somatic hybrids have been created through protoplast fusion of B. oleracea var. botrytis and B. rapa var. oleifera genotypes selected for high erucic acid (22:1) content in the seed oil. Fifty amphidiploids (aacc) and one putative hexaploid (aacccc) hybrid were recovered in one fusion experiment. Conversely, only one amphidiploid and numerous regenerates with higher DNA contents were

  2. Reactions of atomic hydrogen with formic acid and carbon monoxide in solid parahydrogen II: Deuterated reaction studies.

    PubMed

    Wonderly, William R; Anderson, David T

    2014-09-11

    It is difficult to determine whether the measured rate constant for reaction of atomic hydrogen with formic acid reported in Part 1 reflects the H atom quantum diffusion rate or the rate constant for the tunneling reaction step. In Part 2 of this series, we present kinetic studies of the postphotolysis H atom reactions with deuterated formic acid (DCOOD) to address this ambiguity. Short duration 193 nm in situ photolysis of DCOOD trapped in solid parahydrogen results in partial depletion of the DCOOD precursor and photoproduction of primarily CO, CO2, DOCO, HCO and mobile H atoms. At 1.9 K we observe post-irradiation growth in the concentrations of DOCO and HCO that can be explained by H atom tunneling reactions with DCOOD and CO, respectively. Conducting experiments with different deuterium isotopomers of formic acid (DCOOD, DCOOH, HCOOD and HCOOH) provides strong circumstantial evidence the reaction involves H atom abstraction from the alkyl group of formic acid. Further, the anomalous temperature dependence measured for the H + HCOOH reaction in Part 1 is also observed for the analogous reactions with deuterated formic acid. The rate constants extracted for H atom reactions with DCOOD and HCOOH are equivalent to within experimental uncertainty. This lack of a kinetic isotope effect in the measured rate constant is interpreted as evidence the reactions are diffusion limited; the measured rate constant reflects the H atom diffusion rate and not the tunneling reaction rate. Whether or not H atom reactions with chemical species in solid parahydrogen are diffusion limited is one of the outstanding questions in this field, and this work makes significant strides toward showing the reaction kinetics with formic acid are diffusion limited. PMID:25113062

  3. Direct production of crystalline boric acid through heterogeneous reaction of solid borax with propionic acid: Operation and simulation

    Microsoft Academic Search

    Bahman ZareNezhad

    2004-01-01

    The production of boric acid through reaction of borax crystals with propionic acid was investigated in batch mode. It was\\u000a found that the product boric acid precipitates on the solid borax reactant. An increase in the coefficient of variation of\\u000a feed crystals resulted in an increase in the time of completion of the reaction. A sharp interface model with variable

  4. High School Forum: "Invitations to Enquiry": The Calcite/Acid Reaction.

    ERIC Educational Resources Information Center

    Herron, J. Dudley, Ed.; Driscoll, D. R.

    1979-01-01

    Describes a high school chemistry experiment which involves the reaction between calcite and hydrochloric and sulfuric acids. This reaction can be carried out as a projected demonstration and on an individual basis. (HM)

  5. A combined ultracapacitor-lead acid battery storage system for mild hybrid electric vehicles

    Microsoft Academic Search

    Adam W. Stienecker; Thomas Stuart; Cyrus Ashtiani

    2005-01-01

    Improvements in ultracapacitor technology indicate that the automotive industry should re-examine the energy storage system for hybrid electric vehicles (HEVs). With the combination of an ultracapacitor and a lead acid battery, a system can be implemented in which the lead acid battery can be maintained at 100% state of charge, lengthening the lifetime of the battery. Although performance of the

  6. Copper inhibition of the thiobarbituric acid reaction in Bedlington terriers.

    PubMed

    Hultgren, B D; Menken, B Z; Csallany, A S

    1986-04-01

    The effect of copper on thiobarbituric acid (TBA) reaction values, an index of lipid peroxidation, was examined in Bedlington Terriers, healthy dogs, and rats. High hepatic concentrations of copper appeared to lower TBA values in the inherited, chronic, progressive hepatic degeneration of Bedlington Terriers, a disease associated with copper toxicosis. The suspected TBA inhibition was confirmed when Cu2+ was added to homogenates of healthy dog or rat liver or a malondialdehyde standard. The amount of copper added approximated that in diseased Bedlington Terriers. Because of the interference by copper, the TBA test was judged to be an inappropriate test for the evaluation of lipid peroxidation in samples containing high copper concentrations such as those in diseased Bedlington Terriers. PMID:3963583

  7. The Influence of Equilibrium Reactions on the Kinetics of Calcite Dissolution in Lactic Acid Solutions 

    E-print Network

    Shedd, Daniel C

    2014-08-07

    Matrix acidizing has historically been a common means of removing formation damage and increasing the productivity of petroleum wells. Organic acids have been used in an effort to minimize the corrosion problem and the rapid reaction rate...

  8. Organic Chemistry Jasperse Acid-Base Practice Problems A. Identify each chemical as either an "acid" or a "base" in the following reactions, and

    E-print Network

    Jasperse, Craig P.

    Organic Chemistry Jasperse Acid-Base Practice Problems A. Identify each chemical as either an "acid" or a "base" in the following reactions, and identify "conjugate" relationships. -You should have one acid?) 27. 28. G. For the following acid-base reaction, a. put a box around the weakest base in the reaction

  9. Development of a lead-acid battery for a hybrid electric vehicle

    Microsoft Academic Search

    A Cooper

    2004-01-01

    In September 2000, a project reliable, highly optimized lead-acid battery (RHOLAB) started under the UK Foresight Vehicle Programme with the objective of developing an optimized lead-acid battery solution for hybrid electric vehicles. The work is based on a novel, individual, spirally-wound valve-regulated lead-acid 2V cell optimized for HEV use and low variability. This cell is being used as a building

  10. Manipulating the Surface Reactions in Lithium Sulfur Batteries Using Hybrid Anode Structures

    SciTech Connect

    Huang, Cheng; Xiao, Jie; Shao, Yuyan; Zheng, Jianming; Bennett, Wendy D.; Lu, Dongping; Saraf, Laxmikant V.; Engelhard, Mark H.; Ji, Liwen; Zhang, Jiguang; Li, Xiaolin; Graff, Gordon L.; Liu, Jun

    2014-01-09

    Lithium-sulfur (Li-S) batteries have recently attracted extensive attention due to the high theoretical energy density and potential low cost. Even so, significant challenges prevent widespread adoption, including continuous dissolution and consumption of active sulfur during cycling. Here we present a fundamentally new design using electrically connected graphite and lithium metal as a hybrid anode to control undesirable surface reactions on the anode. The lithiated graphite placed in front of the lithium metal functions as an artificial self-regulated solid electrolyte interface (SEI) layer to actively control the electrochemical reaction while minimizing the deleterious side reactions on the surface and bulk lithium metal. Continuous corrosion and contamination of lithium anode by dissolved polysulfides is largely mitigated. Excellent electrochemical performance has been observed. Li-S cell incorporating the hybrid design retain a capacity of more than 800 mAh g-1 for 400 cycles, corresponding to only 11% fade and a Coulombic efficiency above 99%. This simple hybrid concept may also provide new lessons for protecting metal anodes in other energy storage devices.

  11. Differentiation of Mycobacterium tuberculosis Complex and Nontuberculous Mycobacterial Liquid Cultures by Using Peptide Nucleic Acid-Fluorescence In Situ Hybridization Probes

    Microsoft Academic Search

    F. A. DROBNIEWSKI; P. G. MORE; G. S. HARRIS

    2000-01-01

    A blinded comparison of peptide nucleic acid-fluorescence in situ hybridization (PNA-FISH) with routine identification methods was performed on 74 consecutively positive mycobacterial liquid cultures. All Mycobac- terium tuberculosis cultures (48 of 48) and 22 of 27 (81.5%) nontuberculous cultures were correctly identified (including one mixed culture). Five isolates yielded no reaction with either probe and were identified as Mycobacterium xenopi,

  12. Weak Acid Ionization Constants and the Determination of Weak Acid-Weak Base Reaction Equilibrium Constants in the General Chemistry Laboratory

    ERIC Educational Resources Information Center

    Nyasulu, Frazier; McMills, Lauren; Barlag, Rebecca

    2013-01-01

    A laboratory to determine the equilibrium constants of weak acid negative weak base reactions is described. The equilibrium constants of component reactions when multiplied together equal the numerical value of the equilibrium constant of the summative reaction. The component reactions are weak acid ionization reactions, weak base hydrolysis…

  13. Nucleic acid/quantum dots (QDs) hybrid systems for optical and photoelectrochemical sensing.

    PubMed

    Freeman, Ronit; Girsh, Julia; Willner, Itamar

    2013-04-24

    Nucleic acid/semiconductor quantum dots (QDs) hybrid systems combine the recognition and catalytic properties of nucleic acids with the unique photophysical features of QDs. These functions of nucleic acid/QDs hybrids are implemented to develop different optical sensing platforms for the detection of DNA, aptamer-substrate complexes, and metal ions. Different photophysical mechanisms including fluorescence, electron transfer quenching, fluorescence resonance energy transfer (FRET), and chemiluminescence resonance energy transfer (CRET) are used to develop the sensor systems. The size-controlled luminescence properties of QDs are further implemented for the multiplexed, parallel analysis of several DNAs, aptamer-substrate complexes, or mixtures of ions. Similarly, methods to amplify the sensing events through the biocatalytic regeneration of the analyte were developed. An additional paradigm in the implementation of nucleic acid/QDs hybrids for sensing applications involves the integration of the systems with electrodes, and the generation of photocurrents as transduction signals for the sensing events. Finally, semiconductor QDs conjugated to functional DNA machines, such as "walker" systems, provide an effective optical label for probing the dynamics and mechanical functions of the molecular devices. The present article addresses the recent advances in the application of nucleic acid/QDs hybrids for sensing applications and DNA nanotechnology, and discusses future perspectives of these hybrid materials. PMID:23425022

  14. Synthesis and properties of poly(methyl methacrylate-2-acrylamido-2-methylpropane sulfonic acid)/PbS hybrid composite

    SciTech Connect

    Preda, N., E-mail: nicol@infim.ro [National Institute of Materials Physics, Multifunctional Materials and Structures Laboratory, P.O. Box MG-7, 77125 Bucharest (Romania); Rusen, E. [University Politehnica Bucharest, Department of Polymer Science, Calea Victoriei No. 71101, Bucharest (Romania)] [University Politehnica Bucharest, Department of Polymer Science, Calea Victoriei No. 71101, Bucharest (Romania); Musuc, A. [Institute of Physical Chemistry, 060021 Bucharest (Romania)] [Institute of Physical Chemistry, 060021 Bucharest (Romania); Enculescu, M.; Matei, E. [National Institute of Materials Physics, Multifunctional Materials and Structures Laboratory, P.O. Box MG-7, 77125 Bucharest (Romania)] [National Institute of Materials Physics, Multifunctional Materials and Structures Laboratory, P.O. Box MG-7, 77125 Bucharest (Romania); Marculescu, B. [University Politehnica Bucharest, Department of Polymer Science, Calea Victoriei No. 71101, Bucharest (Romania)] [University Politehnica Bucharest, Department of Polymer Science, Calea Victoriei No. 71101, Bucharest (Romania); Fruth, V. [Institute of Physical Chemistry, 060021 Bucharest (Romania)] [Institute of Physical Chemistry, 060021 Bucharest (Romania); Enculescu, I. [National Institute of Materials Physics, Multifunctional Materials and Structures Laboratory, P.O. Box MG-7, 77125 Bucharest (Romania)] [National Institute of Materials Physics, Multifunctional Materials and Structures Laboratory, P.O. Box MG-7, 77125 Bucharest (Romania)

    2010-08-15

    The synthesis of a new hybrid composite based on PbS nanoparticles and poly(methyl methacrylate-2-acrylamido-2-methylpropane sulfonic acid) [P(MMA-AMPSA)] copolymer is reported. The chemical synthesis consists in two steps: (i) a surfactant-free emulsion copolymerization between methyl methacrylate and 2-acrylamido-2-methylpropane sulfonic acid and (ii) the generation of PbS particles in the presence of the P(MMA-AMPSA) latex, from the reaction between lead nitrate and thiourea. The composite was studied by scanning electron microscopy (SEM), X-ray diffraction, FTIR spectroscopy, thermogravimetric analysis and differential scanning calorimetry. The microstructure observed using SEM proves that the PbS nanoparticles are well dispersed in the copolymer matrix. The X-ray diffraction measurements demonstrate that the PbS nanoparticles have a cubic rock salt structure. It was also found that the inorganic semiconductor nanoparticles improve the thermal stability of the copolymer matrix.

  15. Forcing of Turing Patterns in the Chlorine Dioxide-Iodine-Malonic Acid Reaction with Strong Visible Light

    E-print Network

    Epstein, Irving R.

    Forcing of Turing Patterns in the Chlorine Dioxide-Iodine-Malonic Acid Reaction with Strong Visible investigate the sensitivity of Turing patterns in the chlorine dioxide-iodine-malonic acid reaction (CIMA) reaction and its variant, the chlorine dioxide-iodine-malonic acid (CDIMA) reaction, has been

  16. Application of a new hybrid organic–inorganic monolithic column for efficient deoxyribonucleic acid purification

    Microsoft Academic Search

    Shengbing Yu; Jing Geng; Ping Zhou; Jing Wang; Airong Feng; Xiangdong Chen; Hua Tong; Jiming Hu

    2008-01-01

    A new hybrid organic–inorganic monolithic column for efficient deoxyribonucleic acid (DNA) extraction was prepared in situ by polymerization of N-(?-aminoethyl)-?-aminopropyltriethoxysilane (AEAPTES) and tetraethoxysilane (TEOS). The main extraction mechanism was based on the Coulombic force between DNA and the amino silica hybrid monolithic column. DNA extraction conditions, such as pH, ion concentration and type, and loading capacity, were optimized online by

  17. Nanofiltration, bipolar electrodialysis and reactive extraction hybrid system for separation of fumaric acid from fermentation broth.

    PubMed

    Prochaska, Krystyna; Staszak, Katarzyna; Wo?niak-Budych, Marta Joanna; Regel-Rosocka, Magdalena; Adamczak, Michalina; Wi?niewski, Maciej; Staniewski, Jacek

    2014-09-01

    A novel approach based on a hybrid system allowing nanofiltration, bipolar electrodialysis and reactive extraction, was proposed to remove fumaric acid from fermentation broth left after bioconversion of glycerol. The fumaric salts can be concentrated in the nanofiltration process to a high yield (80-95% depending on pressure), fumaric acid can be selectively separated from other fermentation components, as well as sodium fumarate can be conversed into the acid form in bipolar electrodialysis process (stack consists of bipolar and anion-exchange membranes). Reactive extraction with quaternary ammonium chloride (Aliquat 336) or alkylphosphine oxides (Cyanex 923) solutions (yield between 60% and 98%) was applied as the final step for fumaric acid recovery from aqueous streams after the membrane techniques. The hybrid system permitting nanofiltration, bipolar electrodialysis and reactive extraction was found effective for recovery of fumaric acid from the fermentation broth. PMID:24983693

  18. Students' Understanding of Acid, Base and Salt Reactions in Qualitative Analysis.

    ERIC Educational Resources Information Center

    Tan, Kim-Chwee Daniel; Goh, Ngoh-Khang; Chia, Lian-Sai; Treagust, David F.

    2003-01-01

    Uses a two-tier, multiple-choice diagnostic instrument to determine (n=915) grade 10 students' understanding of the acid, base, and salt reactions involved in basic qualitative analysis. Reports that many students did not understand the formation of precipitates and the complex salts, acid/salt-base reactions, and thermal decomposition involved in…

  19. Access to aryl mellitic acid esters through a surprising oxidative esterification reaction.

    PubMed

    Geraskina, Margarita R; Juetten, Mark J; Winter, Arthur H

    2014-06-01

    A serendipitously discovered oxidative esterification reaction of cyclohexane hexacarboxylic acid with phosphorus pentachloride and phenols provides one-pot access to previously unknown aryl mellitic acid esters. The reaction features a solvent-free digestion and chromatography-free purifications and demonstrates the possibility of cyclohexane-to-benzene conversions under relatively mild, metal-free conditions. PMID:24815576

  20. Visible-light-mediated chan-lam coupling reactions of aryl boronic acids and aniline derivatives.

    PubMed

    Yoo, Woo-Jin; Tsukamoto, Tatsuhiro; Kobayashi, Sh?

    2015-05-26

    The copper(II)-catalyzed aerobic oxidative coupling reaction between aryl boronic acids and aniline derivatives was found to be improved significantly under visible-light-mediated photoredox catalysis. The substrate scope of this oxidative Chan-Lam reaction was thus expanded to include electron-deficient aryl boronic acids as viable starting materials. PMID:25873290

  1. Enzymatic Amplification of DNA/RNA Hybrid Molecular Beacon Signaling in Nucleic Acid Detection

    PubMed Central

    Jacroux, Thomas; Rieck, Daniel C.; Cui, Rong; Ouyang, Yexin; Dong, Wen-Ji

    2012-01-01

    A rapid assay operable under isothermal or non-isothermal conditions is described wherein the sensitivity of a typical molecular beacon (MB) system is improved by utilizing thermostable RNase H to enzymatically cleave an MB comprised of a DNA stem and RNA loop (R/D-MB). Upon hybridization of the R/D-MB to target DNA, there was a modest increase in fluorescence intensity (~5.7x above background) due to an opening of the probe and concomitant reduction in the Förster resonance energy transfer efficiency. Addition of thermostable RNase H resulted in the cleavage of the RNA loop which eliminated energy transfer. The cleavage step also released bound target DNA, enabling it to bind to another R/D-MB probe and rendering the approach a cyclic amplification scheme. Full processing of R/D-MBs maximized the fluorescence signal to the fullest extent possible (12.9x above background), resulting in a ~2–2.8 fold increase in the signal-to-noise ratio observed isothermally at 50 °C following the addition of RNase H. The probe was also used to monitor real-time PCR reactions by measuring enhancement of donor fluorescence upon R/D-MB binding to amplified pUC19 template dilutions. Hence, the R/D-MB-RNase H scheme can be applied to a broad range of nucleic acid amplification methods. PMID:23000602

  2. Kinetic Studies on the Reaction between Dicyanocobinamide and Hypochlorous Acid

    PubMed Central

    Maitra, Dhiman; Ali, Iyad; Abdulridha, Rasha M.; Shaeib, Faten; Khan, Sana N.; Saed, Ghassan M.; Pennathur, Subramaniam; Abu-Soud, Husam M.

    2014-01-01

    Hypochlorous acid (HOCl) is a potent oxidant generated by myeloperoxidase (MPO), which is an abundant enzyme used for defense against microbes. We examined the potential role of HOCl in corrin ring destruction and subsequent formation of cyanogen chloride (CNCl) from dicyanocobinamide ((CN)2-Cbi). Stopped-flow analysis revealed that the reaction consists of at least three observable steps, including at least two sequential transient intermediates prior to corrin ring destruction. The first two steps were attributed to sequential replacement of the two cyanide ligands with hypochlorite, while the third step was the destruction of the corrin ring. The formation of (OCl)(CN)-Cbi and its conversion to (OCl)2-Cbi was fitted to a first order rate equation with second order rate constants of 0.002 and 0.0002 µM?1s?1, respectively. The significantly lower rate of the second step compared to the first suggests that the replacement of the first cyanide molecule by hypochlorite causes an alteration in the ligand trans effects changing the affinity and/or accessibility of Co toward hypochlorite. Plots of the apparent rate constants as a function of HOCl concentration for all the three steps were linear with Y-intercepts close to zero, indicating that HOCl binds in an irreversible one-step mechanism. Collectively, these results illustrate functional differences in the corrin ring environments toward binding of diatomic ligands. PMID:25375773

  3. Synthesis and utilization of chitin humic acid hybrid as sorbent for Cr(III)

    NASA Astrophysics Data System (ADS)

    Santosa, Sri Juari; Siswanta, Dwi; Sudiono, Sri; Sehol, Muhamad

    2007-11-01

    New types of hybrid material have been synthesized by using four different methods of immobilization of humic acid (HA) on chitin. The most stable hybrid material toward the change of medium acidity was then utilized as sorbent for Cr(III). The HA was extracted from peat soil of Gambut District, South Kalimantan, Indonesia, using the recommended procedure of International Humic Substances Society (IHSS), while the chitin was isolated from crab shell waste through deproteination using 3.5% (w/v) NaOH and followed by removal of inorganic impurities using 1 M HCl. The four methods of immobilization of HA on chitin were (i) Method A: chitin powder (4 g) was gently poured into the stirred solution of 0.4 g HA in 40 mL of 0.01 M NaOH. After overnight stirring, the solid was separated, washed with water, and dried in oven at 70 °C. (ii) Method B: gelatinous chitin (40 g) in 250 mL of 0.5 M HCl was reacted with HA (4 g) in 500 mL of 0.5 M NaOH and aged for 24 h. The product was washed with water and dried. (iii) Method C: HA powder (0.5 g) was mixed with the stirred gel of chitin (2.5 g) in 60 mL of CaCl 2 saturated methanol and the mixture was then washed with the mixed solution of 25 mL of 2 M sodium citrate and ethylene glycol 1:1. The solid was separated, washed with water, and dried. (iv) Method D: the solution of HA (0.056 g) in 10 mL of 0.01 M NaOH was reacted with the gel of chitin (0.2 g) in 10 mL of CaCl 2 saturated methanol. After 24 h stirring, the solid was separated from the reaction medium, washed with the mixed solution of 2 M sodium citrate and ethylene glycol 1:1, and followed by washing with water and drying. Parameters investigated in this study consisted of the stability test of the immobilized HA, as well as the rate constant ( k1), capacity ( b), and energy ( E) of sorption as well as the rate constant of desorption ( k-1). The k1 and k-1 were determined according to a kinetic model of first order sorption reaching equilibrium, while the b and E were determined according to the Langmuir isotherm model. Compared to HA, Methods, A, C, and D; Method B produced the most stable immobilization of HA on chitin. The hybrid material (Chitin-HA) synthesized through Method B was stable in the acidity range that equivalent to pH 2.0-11.0. At the acidity giving maximum sorption, i.e. pH 5, the presence of immobilized HA on the Chitin-HA enhanced more than three times the k1 and k-1, i.e. from 0.057 min -1 and 8.51 × 10 -4 (min -1) (mol/L) for chitin to 0.183 min -1 and 3.27 × 10 -3 (min -1) (mol/L) for the Chitin-HA. On the contrary, the presence of HA on Chitin-HA only gave small increase on b and small decrease on E. The values of b and E for Cr(III) on chitin were 1.45 × 10 -2 mol/g and 23.12 kJ/mol, respectively, while those on Chitin-HA were 1.78 × 10 -2 mol/g and 19.95 kJ/mol, respectively.

  4. Fluorescent products from reaction of peroxidizing polyunsaturated fatty acids with phosphatidyl ethanolamine and phenylalanine

    Microsoft Academic Search

    C. J. Dillard; A. L. Tappel

    1973-01-01

    Fluorescent chromophores produced by reaction of peroxidizing arachidonic acid or methyl docosahexaenoate with synthetic dipalmityl\\u000a phosphatidyl ethanolamine were lipid soluble, and those from reaction with phenylalanine were water soluble. In all reaction\\u000a systems that contained polyunsaturated fatty acid and only one amine compound, the development of fluorescence was linearly\\u000a related to oxygen absorption for 12–24 hr (p<0.001) and to the

  5. Species-specific assessment of Mycobacterium leprae in skin biopsies by in situ hybridization and polymerase chain reaction.

    PubMed

    Arnoldi, J; Schlüter, C; Duchrow, M; Hübner, L; Ernst, M; Teske, A; Flad, H D; Gerdes, J; Böttger, E C

    1992-05-01

    Conventional histopathologic diagnosis of mycobacterial infections are limited to the determination of "acid-fast bacilli". A species-specific diagnosis is thus far impossible. In addition, routine microbiologic assessments of mycobacteria suffer from the major drawback that a species-specific diagnosis is extremely time-consuming and in several cases even impossible. As Mycobacterium leprae cannot be cultured in vitro, we tried to specifically target this obligate intracellular parasite by in situ hybridization and polymerase chain reaction (PCR) techniques. For this purpose we used a 22 mer oligonucleotide probe recognizing a species-specific sequence of the 16S rRNA of Mycobacterium leprae. Using an immunoenzymatic detection method for in situ hybridization we were able to specifically assess Mycobacterium leprae (a) in long-term cultured macrophages in vitro infected with different mycobacteria species and (b) in frozen sections of skin biopsies obtained from patients suffering from lepromatous leprosy. These results could be confirmed and extended by PCR experiments in which we used conserved oligonucleotide primers for 16S rRNA to amplify bacterial DNA isolated from different eubacterial species and from fresh-frozen as well as from formalin-fixed, paraffin-embedded and routinely processed mycobacteria-infected tissues. Upon Southern blot analysis, the Mycobacterium leprae-specific oligonucleotide probe exclusively hybridized with PCR products obtained from Mycobacterium leprae-containing samples (including paraffin sections), but not with PCR products obtained from samples containing other mycobacterial species. As species-specific oligonucleotide probes targeted at rRNA are described for a variety of mycobacterial species, these methods may be generally applied for a rapid species-specific assessment of mycobacteria in histologic material. PMID:1573855

  6. Mutual storage mode ion/ion reactions in a hybrid linear ion trap.

    PubMed

    Xia, Yu; Wu, Jin; McLuckey, Scott A; Londry, Frank A; Hager, James W

    2005-01-01

    Ion/ion proton transfer reactions involving mutual storage of both ion polarities in a linear ion trap (LIT) that comprises part of a hybrid triple quadrupole/linear ion trap mass spectrometer have been effected. Mutual ion storage in the x- and y-dimensions arises from the normal operation of the oscillating quadrupole field of the quadrupole array, while storage in the z-dimension is enabled by applying unbalanced radio-frequency amplitudes to opposing sets of rods of the array. Efficient trapping (>90%) is achieved for thermalized ions over periods of several seconds. Reactions were demonstrated for multiply charged protein/peptide cations formed by electrospray with anions derived from glow discharge ionization of perfluoro(methyldecalin) (PMD) introduced from the side of the LIT rod array. Doubly and singly charged protein ions are readily formed via ion/ion reactions. The parameters that affect ion/ion reactions are discussed, including the degree of RF unbalance on the LIT rods, vacuum pressure, nature of the buffer gas, reaction time, anion abundance, and the low mass cutoff for ion/ion reaction. The present system has a demonstrated upper mass-to-charge ratio limit of at least 33,000. The system also has high flexibility with respect to defining MS(n) experiments involving both collision-induced dissociation (CID) and ion/ion reactions. Experiments are demonstrated involving beam-type CID in the pressurized collision quadrupole (Q2) followed by ion/ion reactions involving the product ions in the LIT. Ion parking experiments are also demonstrated using the mutual storage ion/ion reaction mode in the LIT, with a parking efficiency over 60%. PMID:15653365

  7. Effects of ultrasound on the reaction step of boric acid production process from colemanite

    Microsoft Academic Search

    N. Taylan; H. Gürbüz; A. N. Bulutcu

    2007-01-01

    Colemanite is one of the most important boron minerals used for production of boric acid. Boric acid (H3BO3) is produced by the reaction of colemanite (2CaO·3B2O3·5H2O) with sulfuric acid in a heterogeneous solid–liquid reaction leading to crystallization of gypsum as a byproduct.The influence of ultrasound on the dissolution of colemanite in H2SO4 solution and on the precipitation of the gypsum

  8. Organo-niobate Ionic Liquids: Synthesis, Characterization and Application as Acid Catalyst in Pechmann Reactions

    PubMed Central

    Soares, Valerio C. D.; Alves, Melquizedeque B.; Souza, Ernesto R.; Pinto, Ivana O.; Rubim, Joel C.; Andrade, Carlos Kleber Z.; Suarez, Paulo A. Z.

    2007-01-01

    The combinations of 1-butyl-3-methylimidazolium chloride with NbCl5 yielded ionic mixtures with different melting point temperatures and acidity depending on the niobium molar fraction. The mixtures were characterized by thermal (DSC) and spectroscopic (FT-IR and 1H NMR) analysis. The Pechmann reactions of different phenols with ethylacetoacetate, producing coumarins, was used as model to evaluate the catalytic behavior of these mixtures as acid Lewis catalyst. These reactions were carried out using acidic mixtures of 60 mol%.

  9. Noncatalytic reaction of isonitriles and carboxylic acids en route to amide-type linkages

    Microsoft Academic Search

    Xuechen Li; Samuel J Danishefsky

    2008-01-01

    This protocol describes the preparation of an N-methyl-asparagine-linked glycosyl amino acid, on the basis of a reaction between carboxylic acids and isonitriles. Under microwave\\/thermolysis, carboxylic acids can couple with isonitriles without an external catalyst to form N-formyl-amides, which may be further advanced to the corresponding amides, N-methyl amide and N-methyloyl amide. The example reaction of ?-galactopyranosyl isonitrile (7) with a

  10. Calorimetric study of the reactions of n-alkylphosphonic acids with metal oxide surfaces

    Microsoft Academic Search

    Jaime M. Ferreira; Stephen Marcinko; Richard Sheardy; Alexander Y. Fadeev

    2005-01-01

    The reaction enthalpies for the solution-phase self-assembly of n-alkylphosphonic acids on the surfaces of TiO2 and ZrO2 have been determined using isothermal titration calorimetry at 298 K. The reaction enthalpies were negative (exothermic) for methyl- and n-octylphosphonic acids and positive (endothermic) for n-octadecylphosphonic acid with both metal oxides. The enthalpy\\/energy analysis showed that the net enthalpy of the formation of

  11. Dibenzo-1,5-diazocine-2,6-dione, 2-iminoindolin-3-one and N-(carbamoylmethyl)-aminobenzoic acid ester from aminobenzoic acid by multicomponent reactions

    Microsoft Academic Search

    Manja Grosche; Eberhardt Herdtweck; Wolfgang A. Herrmann

    1998-01-01

    Aminobenzoic acids show different types of multicomponent reactions when treated with a carbonylic component and an isocyanide in an alcoholic solution. Anthranilic acid provides dibenzo-1,5-diazocine-2,6-dione derivatives by a double Ugi four component reaction (U-4CR) or depending on the reaction conditions the U-5C-4CR product, a N-(carbamoylmethyl)anthranilic acid ester. Whereas anthranilic acid reacts hardly with ketones in that kind of multicomponent reaction.

  12. Kinetic investigation of reaction between ulexite ore and phosphoric acid

    Microsoft Academic Search

    H. Tuba Do?an; Ahmet Yarta??

    2009-01-01

    One of the most important boron minerals, ulexite, is dissolved in aqueous phosphoric acid to produce boric acid whereby sodium and calcium phosphates are formed as byproduct. The dissolution of ulexite in aqueous phosphoric acid solutions was investigated in a batch reactor employing the parameters of stirring speed, particle size, temperature, solid\\/liquid ratio and acid concentration. It was found that

  13. Lead acid battery storage model for hybrid energy systems

    Microsoft Academic Search

    J. F. Manwell; J. G. McGowan

    1993-01-01

    This paper describes a new battery model developed for use in time series performance models of hybrid energy systems. The model is intended to overcome some of the difficulties associated with currently used methods. It is based on the approach of chemical kinetics. This model, which can be used for charging and discharging, is specifically concerned with the apparent change

  14. Templated Synthesis of Peptide Nucleic Acids via Sequence-Selective Base-Filling Reactions

    E-print Network

    Liu, David R.

    Templated Synthesis of Peptide Nucleic Acids via Sequence-Selective Base-Filling Reactions Jennifer describe the templated synthesis of both native and modified peptide nucleic acids (PNAs) through base, 2009; E-mail: drliu@fas.harvard.edu Template-directed nucleic acid synthesis is an essential compo

  15. A simple colorimetric DNA detection by target-induced hybridization chain reaction for isothermal signal amplification.

    PubMed

    Ma, Cuiping; Wang, Wenshuo; Mulchandani, Ashok; Shi, Chao

    2014-07-15

    A novel DNA detection method is presented based on a gold nanoparticle (AuNP) colorimetric assay and hybridization chain reaction (HCR). In this method, target DNA hybridized with probe DNA modified on AuNP, and triggered HCR. The resulting HCR products with a large number of negative charges significantly enhanced the stability of AuNPs, inhibiting aggregation of AuNPs at an elevated salt concentration. The approach was highly sensitive and selective. Using this enzyme-free and isothermal signal amplification method, we were able to detect target DNA at concentrations as low as 0.5 nM with the naked eye. Our method also has great potential for detecting other analytes, such as metal ions, proteins, and small molecules, if the target analytes could make HCR products attach to AuNPs. PMID:24780220

  16. Hyperbranched Hybridization Chain Reaction for Triggered Signal Amplification and Concatenated Logic Circuits.

    PubMed

    Bi, Sai; Chen, Min; Jia, Xiaoqiang; Dong, Ying; Wang, Zonghua

    2015-07-01

    A hyper-branched hybridization chain reaction (HB-HCR) is presented herein, which consists of only six species that can metastably coexist until the introduction of an initiator DNA to trigger a cascade of hybridization events, leading to the self-sustained assembly of hyper-branched and nicked double-stranded DNA structures. The system can readily achieve ultrasensitive detection of target DNA. Moreover, the HB-HCR principle is successfully applied to construct three-input concatenated logic circuits with excellent specificity and extended to design a security-mimicking keypad lock system. Significantly, the HB-HCR-based keypad lock can alarm immediately if the "password" is incorrect. Overall, the proposed HB-HCR with high amplification efficiency is simple, homogeneous, fast, robust, and low-cost, and holds great promise in the development of biosensing, in the programmable assembly of DNA architectures, and in molecular logic operations. PMID:26012841

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

    PubMed

    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/?-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/?-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. PMID:23768320

  18. Thiolated pyrrolidinyl peptide nucleic acids for the detection of DNA hybridization using surface plasmon resonance

    Microsoft Academic Search

    Cheeraporn Ananthanawat; Tirayut Vilaivan; Wanwimon Mekboonsonglarp; Voravee P. Hoven

    2009-01-01

    Thiolated pyrrolidinyl peptide nucleic acids (HS-PNAs) bearing d-prolyl-2-aminocyclopentanecarboxylic acid (ACPC) backbones with different lengths and types of thiol modifiers were synthesized and then characterized by MALDI–TOF mass spectrometry. These HS-PNAs were immobilized on gold-coated glass by self-assembled monolayer (SAM) formation via S atom linkage for the detection of DNA hybridization using surface plasmon resonance (SPR). The amount and the stability

  19. Development and operation of a hybrid acid-alkaline advanced water electrolysis cell

    Microsoft Academic Search

    O. Teschke; M. Zwanziger

    1981-01-01

    A hybrid acid-alkaline water electrolysis cell has been developed for hydrogen production. The cell is based on the use of an acidic solution at the cathode and a basic solution at the anode to reduce the minimum theoretical voltage for water decomposition from the thermoneutral potential of 1.47 V to close to 1.4 V at 25 C and 1 atm.

  20. Hybrid low resistance ultracapacitor electrodes based on 1-pyrenebutyric acid functionalized centimeter-scale graphene sheets.

    PubMed

    Wang, Wei; Guo, Shirui; Penchev, Miroslav; Zhong, Jiebin; Lin, Jian; Bao, Duoduo; Vullev, Valentine; Ozkan, Mihrimah; Ozkan, Cengiz S

    2012-09-01

    Ultracapacitors are promising candidates for alternative energy storage applications since they can store and deliver energy at relatively high rates. Here, we present hybrid nanocarbon ultracapacitor electrodes with a low equivalent series resistance (ESR) of 7 ohms. 1-pyrenebutyric acid treated large-area single layer graphene (SLG) sheets covered with shortened multi-walled carbon nanotubes (MWNTs) have been utilized as highly conductive and percolated networks of hybrid carbon nanomaterial composites or thin films as ultracapacitor electrodes. Uniform centimeter scale single layer graphene sheets were produced via low pressure chemical vapor deposition using copper foil substrates and then subsequently modified by 1-pyrenebutyric acid functionalization. Chemically shortened MWNTs ranging in length of 200-500 nm, were deposited by drop casting on 1-pyrenebutyric acid functionalized SLG films. SLG/MWNT nancomposite hybrid films of different thicknesses were obtained by controlling the density of MWNT suspension. Surface morphology and nanostructure of the hybrid nanocomposites indicated relatively dense and homogeneous web-like networks. Specific capacitance values of the hybrid electrodes were substantially increased by 200% compared to those ultracapacitors fabricated using buckypaper electrodes. Average values of specific capacitance and energy density obtained were 140.64 F/g and 21.54 Wh/kg respectively. SLG/MWNT nanocomposite electrodes are very promising for future ultracapacitor devices with their low ESR value that is 95% lower than that of buckypaper based ultracapacitors. PMID:23035414

  1. Synthesis of high erucic acid rapeseed (Brassica napus L.) somatic hybrids with improved agronomic characters.

    PubMed

    Heath, D W; Earle, E D

    1995-11-01

    Novel Brassica napus somatic hybrids have been created through protoplast fusion of B. oleracea var. botrytis and B. rapa var. oleifera genotypes selected for high erucic acid (22:1) content in the seed oil. Fifty amphidiploids (aacc) and one putative hexaploid (aacccc) hybrid were recovered in one fusion experiment. Conversely, only one amphidiploid and numerous regenerates with higher DNA contents were produced in a similar fusion using a different B. rapa partner. Hybridity was confirmed by morphology, isozyme expression, flow cytometry, and DNA hybridization. Analysis of organellar DNA revealed a distinct bias toward the inheritance of chloroplasts from the B. rapa (aa) genome. All amphidiploids set self-pollinated seed. A erucic acid content as high as 57.4% was found in the seed oil of one regenerated plant. Fatty acid composition was stable in the R1 generation and was coupled with increased female fertility. Other novel agronomic characters in the hybrids recovered include large seed size, lodging resistance, and non-shattering seed pods. PMID:24170008

  2. Local sustained delivery of acetylsalicylic acid via hybrid stent with biodegradable nanofibers reduces adhesion of blood cells and promotes reendothelialization of the denuded artery

    PubMed Central

    Lee, Cheng-Hung; Lin, Yu-Huang; Chang, Shang-Hung; Tai, Chun-Der; Liu, Shih-Jung; Chu, Yen; Wang, Chao-Jan; Hsu, Ming-Yi; Chang, Hung; Chang, Gwo-Jyh; Hung, Kuo-Chun; Hsieh, Ming-Jer; Lin, Fen-Chiung; Hsieh, I-Chang; Wen, Ming-Shien; Huang, Yenlin

    2014-01-01

    Incomplete endothelialization, blood cell adhesion to vascular stents, and inflammation of arteries can result in acute stent thromboses. The systemic administration of acetylsalicylic acid decreases endothelial dysfunction, potentially reducing thrombus, enhancing vasodilatation, and inhibiting the progression of atherosclerosis; but, this is weakened by upper gastrointestinal bleeding. This study proposes a hybrid stent with biodegradable nanofibers, for the local, sustained delivery of acetylsalicylic acid to injured artery walls. Biodegradable nanofibers are prepared by first dissolving poly(D,L)-lactide-co-glycolide and acetylsalicylic acid in 1,1,1,3,3,3-hexafluoro-2-propanol. The solution is then electrospun into nanofibrous tubes, which are then mounted onto commercially available bare-metal stents. In vitro release rates of pharmaceuticals from nanofibers are characterized using an elution method, and a highperformance liquid chromatography assay. The experimental results suggest that biodegradable nanofibers release high concentrations of acetylsalicylic acid for three weeks. The in vivo efficacy of local delivery of acetylsalicylic acid in reducing platelet and monocyte adhesion, and the minimum tissue inflammatory reaction caused by the hybrid stents in treating denuded rabbit arteries, are documented. The proposed hybrid stent, with biodegradable acetylsalicylic acid-loaded nanofibers, substantially contributed to local, sustained delivery of drugs to promote re-endothelialization and reduce thrombogenicity in the injured artery. The stents may have potential applications in the local delivery of cardiovascular drugs. Furthermore, the use of hybrid stents with acetylsalicylic acid-loaded nanofibers that have high drug loadings may provide insight into the treatment of patients with high risk of acute stent thromboses. PMID:24421640

  3. 40 CFR 721.10188 - Fatty acids, tall-oil, reaction products with 4-methyl-2-pentanone and aliphatic polyamine...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...New Uses for Specific Chemical Substances § 721...acids, tall-oil, reaction products with 4-methyl-2-pentanone...generic). (a) Chemical substance and significant...reporting . (1) The chemical substance identified...acids, tall-oil, reaction products with...

  4. 40 CFR 721.6181 - Fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl ether...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6181 Fatty acid, reaction product with substituted...reporting. (1) The chemical substance identified generically as fatty acid, reaction product with...

  5. 40 CFR 721.10189 - Fatty acids, tall-oil, reaction products with (butoxymethyl) oxirane formaldehyde-phenol polymer...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721...acids, tall-oil, reaction products with (butoxymethyl...reporting . (1) The chemical substance identified...acids, tall-oil, reaction products with...

  6. 40 CFR 721.10188 - Fatty acids, tall-oil, reaction products with 4-methyl-2-pentanone and aliphatic polyamine...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...New Uses for Specific Chemical Substances § 721...acids, tall-oil, reaction products with 4-methyl-2-pentanone...generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...acids, tall-oil, reaction products with...

  7. 40 CFR 721.10188 - Fatty acids, tall-oil, reaction products with 4-methyl-2-pentanone and aliphatic polyamine...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...New Uses for Specific Chemical Substances § 721...acids, tall-oil, reaction products with 4-methyl-2-pentanone...generic). (a) Chemical substance and significant...reporting . (1) The chemical substance identified...acids, tall-oil, reaction products with...

  8. 40 CFR 721.10188 - Fatty acids, tall-oil, reaction products with 4-methyl-2-pentanone and aliphatic polyamine...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...New Uses for Specific Chemical Substances § 721...acids, tall-oil, reaction products with 4-methyl-2-pentanone...generic). (a) Chemical substance and significant...reporting . (1) The chemical substance identified...acids, tall-oil, reaction products with...

  9. 40 CFR 721.10188 - Fatty acids, tall-oil, reaction products with 4-methyl-2-pentanone and aliphatic polyamine...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...New Uses for Specific Chemical Substances § 721...acids, tall-oil, reaction products with 4-methyl-2-pentanone...generic). (a) Chemical substance and significant...reporting . (1) The chemical substance identified...acids, tall-oil, reaction products with...

  10. Uptake of Hypobromous Acid (HOBr) by Aqueous Sulfuric Acid Solutions: Low-Temperature Solubility and Reaction

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Michelsen, Rebecca R.; Ashbourn, Samatha F. M.; Rammer, Thomas A.; Golden, David M.

    2005-01-01

    Hypobromous acid (HOBr) is a key species linking inorganic bromine to the chlorine and odd hydrogen chemical families. We have measured the solubility of HOBr in 45 - 70 wt% sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosol composition. Over the temperature range 201 - 252 K, HOBr is quite soluble in sulfuric acid, with an effective Henry's law coefficient, H* = 10(exp 4) - 10(exp 7) mol/L/atm. H* is inversely dependent on temperature, with Delta H = -46.2 kJ/mol and Delta S = -106.2 J/mol/K for 55 - 70 wt% H2SO4 solutions. Our study includes temperatures which overlap both previous measurements of HOBr solubility. For uptake into aqueous 45 wt% H2SO4, the solubility can be described by log H* = 3665/T - 10.63. For 55 - 70 wt% H2SO4, log H* = 2412/T - 5.55. At temperatures colder than approx. 213 K, the solubility of HOBr in 45 wt% H2SO4 is noticeably larger than in 70 wt% H2SO4. The solubility of HOBr is comparable to that of HBr, indicating that upper tropospheric and lower stratospheric aerosols should contain equilibrium concentrations of HOBr which equal or exceed those of HBr. Our measurements indicate chemical reaction of HOBr upon uptake into aqueous sulfuric acid in the presence of other brominated gases followed by evolution of gaseous products including Br2O and Br2, particularly at 70 wt% H2SO4.

  11. An ultracapacitor circuit for reducing sulfation in lead acid batteries for Mild Hybrid Electric Vehicles

    Microsoft Academic Search

    Adam W. Stienecker; Thomas Stuart; Cyrus Ashtiani

    2006-01-01

    The nickel metal hydride (NiMH) batteries used in most hybrid electric vehicles (HEVs) provide satisfactory performance, but are quite expensive. In spite of their lower energy density, lead acid batteries would be much more economical except they are prone to sulfation in HEV applications. However, sulfation can be greatly reduced by a circuit that uses an ultracapacitor in conjunction with

  12. Production of propylene glycol fatty acid monoesters by lipase-catalyzed reactions in organic solvents

    Microsoft Academic Search

    Jei-Fu Shaw; Shian Lo

    1994-01-01

    Fatty acid monoesters of propylene glycol (1,2-propanediol) are good water-in-oil emulsifiers. These esters were synthesized\\u000a enzymatically to overcome the problems associated with chemical processes. APseudomonas lipase was added to reaction mixtures containing propylene glycol and various acyl donors (fatty acids, fatty acid ethyl\\u000a esters, fatty acid anhydrides and triglycerides) in organic solvents, and the mixtures were shaken at 30C. The

  13. Effects of network dissolution changes on pore-to-core up-scaled reaction rates for kaolinite and anorthite reactions under acidic conditions

    E-print Network

    New York at Stoney Brook, State University of

    and anorthite reactions under acidic conditions Daesang Kim1 and W. Brent Lindquist2 * 1 King Abdullah the predictions of a continuum model. Specifically, we6 modeled anorthite and kaolinite reactions under acidic flow conditions during which the7 anorthite reactions remain far from equilibrium (dissolution only

  14. Conservation of Salmonella typhimurium deoxyribonucleic acid in partially diploid hybrids of Escherichia coli.

    PubMed

    Johnson, E M; Craig, W G; Wohlhieter, J A; Lazere, J R; Synenki, R M; Baron, L S

    1973-08-01

    Partially diploid Escherichia coli K-12 hybrids recovered from mating with a Salmonella typhimurium Hfr strain were found to differ with respect to the manner in which they conserved the added Salmonella deoxyribonucleic acid (DNA). Five of the diploid hybrids examined appeared to maintain the Salmonella DNA as part of a functional F-merogenote; these hybrids were sensitive to the male-specific phage, R-17, responded as males to the female-specific phage, phiII, and transferred their inherited Salmonella genetic markers at high frequency in conjugation experiments. Six diploid hybrids were observed which were not sensitive to R-17, and from which the added Salmonella DNA was not transmissible in conjugation tests; nevertheless, these hybrids responded as males to phiII, and the Salmonella chromosomal fragments were conserved in them as parts of supercoiled, circular DNA elements. It was concluded that these circular DNA elements were defective F-merogenotes, unable to direct the synthesis of F-pili. Three diploid hybrids were found which were not sensitive to R-17, and which responded as females to phiII; no circular DNA was found in them, and it was concluded that their conservation of the Salmonella genetic fragments was accomplished in some manner which did not involve association with F or assumption of the supercoiled circular configuration. Other partially diploid hybrids were observed which appeared similar to these latter three hybrids with regard to their conservation of the Salmonella DNA, but which also contained an infecting F-factor; in these hybrids, both genetic and molecular experiments indicated that the unstably conserved Salmonella DNA was not associated physically with the F-factor. PMID:4579875

  15. Enzyme-free colorimetric detection of DNA by using gold nanoparticles and hybridization chain reaction amplification.

    PubMed

    Liu, Pei; Yang, Xiaohai; Sun, Shan; Wang, Qing; Wang, Kemin; Huang, Jin; Liu, Jianbo; He, Leiliang

    2013-08-20

    A novel, high sensitive, and specific DNA assay based on gold nanoparticle (AuNP) colorimetric detection and hybridization chain reaction (HCR) amplification has been demonstrated in this article. Two hairpin auxiliary probes were designed with single-stranded DNA (ssDNA) sticky ends which stabilize AuNPs and effectively prevent them from salt-induced aggregation. The target DNA hybridized with the hairpin auxiliary probes and triggered the formation of extended double-stranded DNA (dsDNA) polymers through HCR. As a result, the formed dsDNA polymers provide less stabilization without ssDNA sticky ends, and AuNPs undergo aggregation when salt concentration is increased. Subsequently, a pale purple-to-blue color variation is observed in the colloid solution. The system is simple in design and convenient in operation. The novel strategy eliminates the need for enzymatic reactions, separation processes, chemical modifications, and sophisticated instrumentation. The detection and discrimination process can be seen with the naked eye. The detection limit of this method is lower than or at least comparable to previous AuNP-based methods. Importantly, the protocol offers high selectivity for the determination between perfectly matched target oligonucleotides and targets with single base-pair mismatches. PMID:23895103

  16. Quantitative detection of tumor necrosis factor-? by single molecule counting based on a hybridization chain reaction.

    PubMed

    Dai, Shuang; Feng, Chunjing; Li, Wei; Jiang, Wei; Wang, Lei

    2014-10-15

    This work reports a novel and sensitive quantitative method for detection of tumor necrosis factor-? (TNF-?) based on single molecule counting and hybridization chain reaction (HCR). In the presence of TNF-?, sandwich-type immunocomplex was formed on the surface of glass substrate. The streptavidin acted as a bridge bounded to the biotinylated immunocomplex, which provided three sites to fixate the biotinylated initiator strands. The initiator strands triggered the chain reaction of hybridization to form a long double-helix polymer and SYBR Green I, acted as the fluorescence label, intercalated into the grooves of the long dsDNA polymer. Then, the quantitative detection of TNF-? was realized by single molecule counting. Under the optimal conditions, HCR-based single molecule counting quantitative method could successfully detect TNF-? in the range of 50 fM to 1 pM, and it revealed a reliable result for TNF-? detection in real serum. Moreover, the proposed immunosensor exhibited excellent specificity. These results greatly demonstrated that the proposed method possessed the potentiality in clinical application and it was suitable for quantification of biomarker under low concentration. PMID:24800682

  17. Clean synthesis in water. Part 2: Uncatalysed condensation reaction of Meldrum's acid and aldehydes

    Microsoft Academic Search

    Franca Bigi; Silvia Carloni; Leonetto Ferrari; Raimondo Maggi; Alessandro Mazzacani; Giovanni Sartori

    2001-01-01

    The environment-friendly condensation of Meldrum's acid and aromatic, heteroaromatic and hindered aliphatic aldehydes is performed carrying out the reaction in water at 75°C for 2 h, avoiding the addition of any catalyst.

  18. The reaction of cesium hydroxide with 4-phenylvaleric acid 

    E-print Network

    Caughfield, Arvie Jeane

    1967-01-01

    , it seems rcasona'ole to concluc -. that there occurs no z-bondin& to thc phenyl r'ng o ti-, e acid since no significant change in thc position or shape of the ring proton. peak is evident. Typical examples of these '. I~K spectra aze shown in Figures 14... Acid Added (ml. ) Figure 4bs Potentiometric Titration of Cesium Hydroxide with 4-Phenylvaleric Acid 29 1. 5 0. 85 Holes of Acid 0 per ''!ole o Bas ' 1. 3 1. 2 D 1 0 0. 6 0. 5 30. 0 ml. of 0. 925 ". ! CsOH 0. 4 0. 3 0. 2 0. 1 7 Moles...

  19. Molecular hybridization between rat liver deoxyribonucleic acid and complementary ribonucleic acid.

    PubMed

    Melli, M; Bishop, J O

    1970-11-01

    RNA (cRNA) was synthesized in vitro on a template of rat liver DNA and its hybridization with rat liver DNA was studied by using the nitrocellulose-filter method. Sonication of the DNA diminished its apparent capacity to hybridize with RNA by about 50%. This is not due to cross-linkage of DNA molecules, because it could be shown that less than 2% of the sonicated DNA was cross-linked. The effect is due instead to the small size of the sonicated DNA molecules. Below a single-stranded molecular weight of 5x10(5) the DNA showed a progressive loss of capacity to hybridize with decrease in molecular weight. Evidence is presented suggesting that the apparently diminished capacity of the DNA to hybridize is due to loss of hybridized DNA from the membrane filters. When cRNA at concentrations of up to 25mug/ml is annealed with sonicated total DNA, an apparent hybridization saturation value is found at which about 2.5% of the DNA is hybridized with RNA. Increasing the cRNA concentration tenfold brought about the hybridization of a second component of the DNA approximately equal in amount to the first. The renaturation of rat liver DNA was studied by measuring the fall in the extinction at 260nm and two different components of renaturation were observed within the reiterated fraction of DNA. By hybridizing cRNA with different fractions of rat DNA the two components of the hybridization curve are shown to correspond to the two components of the renaturation curve. The conclusion is drawn that at a cRNA concentration of 250mug/ml most of the reiterated fraction of rat liver DNA is hybridized after annealing for 16h under standard conditions (0.30m-sodium chloride-30mm-sodium citrate at 65 degrees C). Even with such a high cRNA concentration little or no hybridization of the slowly renaturing DNA fraction occurs. It is suggested that the most highly reiterated DNA component is poorly transcribed in vitro. PMID:5493851

  20. Citric acid-modified Fenton's reaction for the oxidation of chlorinated ethylenes in soil solution systems.

    PubMed

    Seol, Yongkoo; Javandel, Iraj

    2008-06-01

    Fenton's reagent, a solution of hydrogen peroxide and ferrous iron catalyst, is used for an in situ chemical oxidation of organic contaminants. Sulfuric acid is commonly used to create an acidic condition needed for catalytic oxidation. Fenton's reaction often involves pressure buildup and precipitation of reaction products, which can cause safety hazards and diminish efficiency. We selected citric acid, a food-grade substance, as an acidifying agent to evaluate its efficiencies for organic contaminant removal in Fenton's reaction, and examined the impacts of using citric acid on the unwanted reaction products. A series of batch and column experiments were performed with varying H2O2 concentrations to decompose selected chlorinated ethylenes. Either dissolved iron from soil or iron sulfate salt was added to provide the iron catalyst in the batch tests. Batch experiments revealed that both citric and sulfuric acid systems achieved over 90% contaminant removal rates, and the presence of iron catalyst was essential for effective decontamination. Batch tests with citric acid showed no signs of pressure accumulation and solid precipitations, however the results suggested that an excessive usage of H2O2 relative to iron catalysts (Fe2+/H2O2<1/330) would result in lowering the efficiency of contaminant removal by iron chelation in the citric acid system. Column tests confirmed that citric acid could provide suitable acidic conditions to achieve higher than 55% contaminant removal rates. PMID:18472129

  1. Modeling the reaction kinetics of a hydrogen generator onboard a fuel cell -- Electric hybrid motorcycle

    NASA Astrophysics Data System (ADS)

    Ganesh, Karthik

    Owing to the perceived decline of the fossil fuel reserves in the world and environmental issues like pollution, conventional fuels may be replaced by cleaner alternative fuels. The potential of hydrogen as a fuel in vehicular applications is being explored. Hydrogen as an energy carrier potentially finds applications in internal combustion engines and fuel cells because it is considered a clean fuel and has high specific energy. However, at 6 to 8 per kilogram, not only is hydrogen produced from conventional methods like steam reforming expensive, but also there are storage and handling issues, safety concerns and lack of hydrogen refilling stations across the country. The purpose of this research is to suggest a cheap and viable system that generates hydrogen on demand through a chemical reaction between an aluminum-water slurry and an aqueous sodium hydroxide solution to power a 2 kW fuel cell on a fuel cell hybrid motorcycle. This reaction is essentially an aluminum-water reaction where sodium hydroxide acts as a reaction promoter or catalyst. The Horizon 2000 fuel cell used for this purpose has a maximum hydrogen intake rate of 28 lpm. The study focuses on studying the exothermic reaction between the reactants and proposes a rate law that best describes the rate of generation of hydrogen in connection to the surface area of aluminum available for the certain reaction and the concentration of the sodium hydroxide solution. Further, the proposed rate law is used in the simulation model of the chemical reactor onboard the hybrid motorcycle to determine the hydrogen flow rate to the fuel cell with time. Based on the simulated rate of production of hydrogen from the chemical system, its feasibility of use on different drive cycles is analyzed. The rate of production of hydrogen with a higher concentration of sodium hydroxide and smaller aluminum powder size was found to enable the installation of the chemical reactor on urban cycles with frequent stops and starts. However, by extrapolating the necessary rate of concentration of sodium hydroxide required to produce hydrogen rates that would enable use of the system on highway drive cycles, it was deemed unsafe due to the caustic nature of the solution used.

  2. The kinetics of the esterification reaction between castor oil and oleic acid

    Microsoft Academic Search

    A. T. Erciyes; L. Dandik; O. S. Kabasakal

    1991-01-01

    In this study, esterification of castor oil with oleic acid was investigated in view of the reaction kinetics under various\\u000a conditions. Potassium hydroxide,p-toluenesulfonic acid and tin chloride (SnCl22H2O) were used as catalysts. Reaction was carried out at 200C, 225C and 250 C by using equivalent proportions of the reactants.\\u000a For tin chloride, experimental data fitted the second-order rate equation, while

  3. Design of an innovative lead-acid battery for electric and hybrid vehicles

    SciTech Connect

    Baxa, M.S.; Weinlein, C.E.

    1982-01-01

    Utilizing the technology developed at Globe over the last few years with funding assistance from the DOE, an innovative lead-acid battery has been designed specifically for use in a hybrid car. The battery has exceeded all of the minimum performance goals, and in many cases the optimistic target goals. The eV-1300, which features electrolyte circulation, has excellent energy density, power characteristics, efficiency, and cycle life. It is a good candidate battery for other hybrid vehicles and electric vehicles which require a relatively small cell size.

  4. AEROSOL ACIDITY DETERMINATION BY REACTION WITH 14C LABELED AMINE

    EPA Science Inventory

    The acidity of aerosol particles collected on Teflon membrane filters is analyzed by exposure to 14C labeled trimethylamine and by counting the resulting beta-ray emission. An accurate calibration is established by the use of known, laboratory generated sulfuric acid samples. For...

  5. Natural DNA-modified graphene/Pd nanoparticles as highly active catalyst for formic acid electro-oxidation and for the Suzuki reaction.

    PubMed

    Qu, Konggang; Wu, Li; Ren, Jinsong; Qu, Xiaogang

    2012-09-26

    Natural DNA has been considered as a building block for developing novel functional materials. It is abundant, renewable, and biodegradable and has a well-defined structure and conformation with many unique features, which are difficult to find in other polymers. Herein, calf thymus DNA modified graphene/Pd nanoparticle (DNA-G-Pd) hybrid materials are constructed for the first time using DNA as a mediator, and the prepared DNA-G-Pd hybrid shows high catalytic activity for fuel cell formic acid electro-oxidation and for organic Suzuki reaction. The main advantages of using DNA are not only because the aromatic nucleobases in DNA can interact through ?-? stacking with graphene basal surface but also because they can chelate Pd via dative bonding in such defined sites along the DNA lattice. Our results indicate that isolated, homogeneous, and ultrafine spherical Pd nanoparticles are densely in situ decorated on DNA-modified graphene surfaces with high stability and dispersibility. The prepared DNA-G-Pd hybrid has much greater activity and durability for formic acid electro-oxidation than the commercial Pd/C catalyst and polyvinylpyrrolidone-mediated graphene/Pd nanoparticle (PVP-G-Pd) hybrid used for direct formic acid fuel cells (DFAFCs). Besides, the DNA-G-Pd hybrid can also be an efficient and recyclable catalyst for the organic Suzuki reaction in aqueous solution under aerobic conditions without any preactivation. Since DNA can chelate various transition metal cations, this proof-of-concept protocol provides the possibility for the tailored design of other novel catalytic materials based on graphene with full exploitation of their properties. PMID:22973944

  6. HMDS-promoted in situ amidation reactions of car?ylic acids and amines

    Microsoft Academic Search

    Wen-Chih Chou; Ming-Chen Chou; Yann-Yu Lu; Shyh-Fong Chen

    1999-01-01

    A number ofN-acylalkylenediamines were synthesized in high yields byin situ monoamidation of car?ylic acids with diamines. The amidation reactions were carried out simply by heating the substrates at 110 °C for 5–24 h in the presence of HMDS.HMDS-promotedin situ amidation reactions are generally applicable to the synthesis ofN-acylalkylenediamines.

  7. The temperature dependence of the rate constant for the reaction of hydroxyl radicals with nitric acid

    NASA Technical Reports Server (NTRS)

    Kurylo, M. J.; Cornett, K. D.; Murphy, J. L.

    1982-01-01

    The rate constant for the reaction of hydroxyl radicals with nitric acid in the 225-443 K temperature range has been measured by means of the flash photolysis resonance fluorescence technique. Above 300 K, the rate constant levels off in a way that can only be explained by the occurrence of two reaction channels, of which one, operative at low temperatures, proceeds through the formation of an adduct intermediate. The implications of these rate constant values for stratospheric reaction constants is discussed.

  8. Elucidating the hard/soft acid/base principle: A perspective based on half-reactions

    SciTech Connect

    Ayers, Paul W.; Parr, Robert G.; Pearson, Ralph G. [Department of Chemistry, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514 (United States); Department of Chemistry and Biochemistry, University of California-Santa Barbara, Santa Barbara, California 93106 (United States)

    2006-05-21

    A comprehensive analysis is presented for the acid-base double-exchange reaction as well as the associated acid-displacement and base-displacement 'half-reactions' with the goal of elucidating the meaning of the hard/soft acid/base (HSAB) principle and the conditions for its validity. When electron-transfer effects are important and other effects are negligible, the HSAB principle is driven by the surpassing stability of the soft acid/soft base product. When electrostatic effects dominate the reactivity, the HSAB principle is driven by the surpassing stability of the hard acid/hard base product. Because electron-transfer effects favor soft/soft interactions, while electrostatic effects favor hard/hard interactions, acid-base exchange reactions may be used to determine whether a reagent's reactivity is dominated by electron-transfer or by electrostatic effects. Because electron-transfer and electrostatic considerations separately favor the HSAB principle whenever the electronic chemical potentials of the acids and bases involved in the reaction are similar, our analysis provides strong support for the HSAB principle. The electronic chemical potential measures the intrinsic strength of acids and bases.

  9. A Comparative Study of French and Turkish Students' Ideas on Acid-Base Reactions

    ERIC Educational Resources Information Center

    Cokelez, Aytekin

    2010-01-01

    The goal of this comparative study was to determine the knowledge that French and Turkish upper secondary-school students (grades 11 and 12) acquire on the concept of acid-base reactions. Following an examination of the relevant curricula and textbooks in the two countries, 528 students answered six written questions about the acid-base concept.…

  10. The kinetics and mechanisms of the reactions of aluminium(III) with gallic acid, gallic acid methyl ester and adrenaline

    Microsoft Academic Search

    Máirt??n Ó’Coinceanainn; Michael J. Hynes

    2001-01-01

    The kinetics and mechanisms of the reactions of gallic acid, gallic acid methyl ester and adrenaline with aluminium(III) have been investigated in aqueous solution at 25°C and an ionic strength of 0.5 M. A mechanism has been proposed which accounts satisfactorily for the kinetic data. This is consistent with a mechanism in which complex formation takes place almost exclusively by

  11. KINETIC STUDIES ON REACTION OF SULFINIC ACIDS WITH CONJUGATED ALKENES: I. KINETICS OF THE ADDITION OF ARENESULFINIC ACIDS TO ? -NITROSTYRENE

    Microsoft Academic Search

    D. I. Aleksiev; S. Ivanova; Tashkova Kr

    1993-01-01

    Addition of unsubstituted and substituted benzenesulfinic acids to ?-nitrostyrene has been studied kinetically by means of ultraviolet spectrophotometry. The reaction follows the second-order kinetics: v=k. [?-nitrostyrene][sulfinic acid]. The dependence of rate constants on the temperature and influence of ?-substituents on the kinetic parameters have been investigated. The activating energy and the enthalpy of activation are calculated in the temperature range

  12. A new reaction of unsaturated fatty acid hydroperoxides: Formation of 11-hydroxy-12,13-epoxy-9-octadecenoic acid from 13-hydroperoxy-9,11-octadecadienoic acid

    Microsoft Academic Search

    Mats Hamberg; Birgitta Gotthammar

    1973-01-01

    One of the main compounds formed from 13L-hydroperoxy-9cis,11trans-octadecadienoic acid anaerobically at 100 C in aqueous ethanol was found to bethreo-11-hydroxy-12,13-epoxy-9-octadecenoic acid. The major part (ca. 90%) of this compound was formed from the fatty acid hydroperoxide\\u000a in a reaction involvingcis-addition to the ?11 double bond of the proximally linked hydroperoxide oxygen and hydroxyl ion or hydroxyl radical from the solvent.

  13. A general strategy for nanohybrids synthesis via coupled competitive reactions controlled in a hybrid process.

    PubMed

    Wang, Rongming; Yang, Wantai; Song, Yuanjun; Shen, Xiaomiao; Wang, Junmei; Zhong, Xiaodi; Li, Shuai; Song, Yujun

    2015-01-01

    A new methodology based on core alloying and shell gradient-doping are developed for the synthesis of nanohybrids, realized by coupled competitive reactions, or sequenced reducing-nucleation and co-precipitation reaction of mixed metal salts in a microfluidic and batch-cooling process. The latent time of nucleation and the growth of nanohybrids can be well controlled due to the formation of controllable intermediates in the coupled competitive reactions. Thus, spatiotemporal-resolved synthesis can be realized by the hybrid process, which enables us to investigate nanohybrid formation at each stage through their solution color changes and TEM images. By adjusting the bi-channel solvents and kinetic parameters of each stage, the primary components of alloyed cores and the second components of transition metal doping ZnO or Al2O3 as surface coatings can be successively formed. The core alloying and shell gradient-doping strategy can efficiently eliminate the crystal lattice mismatch in different components. Consequently, varieties of gradient core-shell nanohybrids can be synthesized using CoM, FeM, AuM, AgM (M = Zn or Al) alloys as cores and transition metal gradient-doping ZnO or Al2O3 as shells, endowing these nanohybrids with unique magnetic and optical properties (e.g., high temperature ferromagnetic property and enhanced blue emission). PMID:25818342

  14. A General Strategy for Nanohybrids Synthesis via Coupled Competitive Reactions Controlled in a Hybrid Process

    PubMed Central

    Wang, Rongming; Yang, Wantai; Song, Yuanjun; Shen, Xiaomiao; Wang, Junmei; Zhong, Xiaodi; Li, Shuai; Song, Yujun

    2015-01-01

    A new methodology based on core alloying and shell gradient-doping are developed for the synthesis of nanohybrids, realized by coupled competitive reactions, or sequenced reducing-nucleation and co-precipitation reaction of mixed metal salts in a microfluidic and batch-cooling process. The latent time of nucleation and the growth of nanohybrids can be well controlled due to the formation of controllable intermediates in the coupled competitive reactions. Thus, spatiotemporal-resolved synthesis can be realized by the hybrid process, which enables us to investigate nanohybrid formation at each stage through their solution color changes and TEM images. By adjusting the bi-channel solvents and kinetic parameters of each stage, the primary components of alloyed cores and the second components of transition metal doping ZnO or Al2O3 as surface coatings can be successively formed. The core alloying and shell gradient-doping strategy can efficiently eliminate the crystal lattice mismatch in different components. Consequently, varieties of gradient core-shell nanohybrids can be synthesized using CoM, FeM, AuM, AgM (M = Zn or Al) alloys as cores and transition metal gradient-doping ZnO or Al2O3 as shells, endowing these nanohybrids with unique magnetic and optical properties (e.g., high temperature ferromagnetic property and enhanced blue emission). PMID:25818342

  15. Syntheses of Papyracillic Acids: Application of the Tandem Chain Extension-Acylation Reaction

    PubMed Central

    Mazzone, Jennifer R.; Zercher, Charles K.

    2012-01-01

    A synthetic approach to the papyracillic acid family of natural products has been developed. The spiroacetal core is rapidly assembled through an unprecedented zinc carbenoid-mediated tandem chain extension-acylation reaction. Subsequent functional group manipulation provided access to papyracillic acid B and 4-epi-papyracillic acid C. The successful preparation of these molecules resulted in the clarification of structural assignments of members of this family of natural products. PMID:23013246

  16. Thermal denaturation of double-stranded nucleic acids: prediction of temperatures critical for gradient gel electrophoresis and polymerase chain reaction.

    PubMed Central

    Steger, G

    1994-01-01

    A program is described which calculates the thermal stability and the denaturation behaviour of double-stranded DNAs and RNAs up to a length of 1000 base pairs. The algorithm is based on recursive generation of conditional and a priori probabilities for base stacking. Output of the program may be compared directly to experimental results; thus the program may be used to optimize the nucleic acid fragments, the primers and the experimental conditions prior to experiments like polymerase chain reactions, temperature-gradient gel electrophoresis, denaturing-gradient gel electrophoresis and hybridizations. The program is available in three versions; the first version runs interactively on VAXstations producing graphics output directly, the second is implemented as part of the HUSAR package at GENIUSnet, the third runs on any computer producing text output which serves as input to available graphics programs. Images PMID:8052531

  17. Amino Acid and Anticodon Enhance Metabolic Reaction Rates Weakly but Specifically: Genetic Code World

    NASA Astrophysics Data System (ADS)

    Shimizu, Mikio

    2007-05-01

    Some hydrophilic amino acids such as glutamic acid, lysine, cysteine, and tyrosine having the side chains whose pKR are in or near the physiological pH range were shown to act as rate-enhancers or catalysts in various metabolic reactions weakly but specifically, as well as histidine discussed earlier. Anticodonic tri-ribonucleotides corresponding to the above amino acid catalysts (for example, UpUpU to lysine) also acted as catalysts similarly in each metabolic reaction. The primitive cell containing these molecules and metabolites could be the first minimal biomolecular system with metabolism and inheritance, possibly called as genetic code world.

  18. The Use of Atomic Force Microscopy for 3D Analysis of Nucleic Acid Hybridization on Microarrays

    PubMed Central

    Dubrovin, E. V.; Presnova, G. V.; Rubtsova, M. Yu.; Egorov, A. M.; Grigorenko, V. G.; Yaminsky, I. V.

    2015-01-01

    Oligonucleotide microarrays are considered today to be one of the most efficient methods of gene diagnostics. The capability of atomic force microscopy (AFM) to characterize the three-dimensional morphology of single molecules on a surface allows one to use it as an effective tool for the 3D analysis of a microarray for the detection of nucleic acids. The high resolution of AFM offers ways to decrease the detection threshold of target DNA and increase the signal-to-noise ratio. In this work, we suggest an approach to the evaluation of the results of hybridization of gold nanoparticle-labeled nucleic acids on silicon microarrays based on an AFM analysis of the surface both in air and in liquid which takes into account of their three-dimensional structure. We suggest a quantitative measure of the hybridization results which is based on the fraction of the surface area occupied by the nanoparticles.

  19. Characterization of the products formed by the reaction of trichlorocyanuric acid with 2-propanol.

    PubMed

    Sandercock, P Mark L; Barnett, Julie S

    2009-11-01

    We report a recent investigation into the death of a cat that was initially thought to involve intentionally burning the animal via the use of an ignitable liquid. The exposure of the animal to flame was ruled out. Instead, forensic investigation revealed the intentional mixing together of a common outdoor swimming pool chlorinator, trichlorocyanuric acid (TCCA), and 2-propanol (aka, isopropyl alcohol or rubbing alcohol). The reaction of these two chemicals resulted in the formation of cyanuric acid residue, hydrochloric acid, and the evolution of a significant volume of chlorine gas. Further alpha-chlorination side reactions also occurred between 2-propanol and TCCA to produce a variety of chlorinated 2-propanone species that were detected on the submitted evidence. The identification of the products of both the main reaction and the side reactions allowed the authors to determine what chemicals were originally mixed together by the culprit. PMID:19818110

  20. Refined understanding of sulfur amino acid nutrition in hybrid striped bass, Morone chrysops (male symbol) x M. saxatilis (female symbol) 

    E-print Network

    Kelly, Mark Christopher

    2005-08-29

    Previous studies have indicated the level of total sulfur amino acids (TSAA) (methionine + cystine) is most limiting in practical diet formulations for hybrid striped bass (HSB), especially if animal feedstuffs are replaced with plant feedstuffs...

  1. Modified Anopore™ hybrid membranes for the microfiltration of cellulose acid hydrolysis mixtures

    Microsoft Academic Search

    Yong-Hong Zhao; Daniel F. Shantz

    2011-01-01

    Three classes of nonfouling substances, poly[poly(ethylene glycol) methyl ether methacrylate] (POEM), poly(sulfobetaine methacrylate) (PSBMA), and perfluoroalkyl tagged poly(ethylene glycol) surfactants (fPEG) were covalently tethered onto the surface of Anopore™ membranes (nominal pore size 0.2?m) to form a series of organic–inorganic hybrid membranes. These membranes were then used for the microfiltration of cellulose acid hydrolysis mixtures. Flux recoveries of over 80%

  2. In vivo hybridization of technetium-99m-labeled peptide nucleic acid (PNA)

    Microsoft Academic Search

    G. Mardirossian; K. Lei; M. Rusckowski

    1997-01-01

    Hybridization of a radiolabeled single-stranded DNA oligonucleotide with its single-stranded complement in vivo has not yet been convincingly demonstrated. A contributing factor may be unfavorable in vivo properties of the phosphodiester and phosphorothioate DNAs. Peptide nucleic acid (PNA) oligomers have been reported to possess in vivo properties more suitable for radiopharmaceutical applications. We have radiolabeled an amine-derivatized 15-base PNA oligomer

  3. Graphene quantum dot hybrids as efficient metal-free electrocatalyst for the oxygen reduction reaction.

    PubMed

    Liu, Yong; Wu, Peiyi

    2013-04-24

    The doping of heteroatoms into graphene quantum dot nanostructures provides an efficient way to tune the electronic structures and make more active sites for electro-catalysis, photovoltaic, or light emitting applications. Other than the modification of chemical composition, novel architecture is very desirable to enrich the research area and provides a wide range of choices for the diverse applications. Herein, we show a novel lotus seedpod surface-like pattern of zero-dimension (0D) seed-like N-GODs of ca.3 nm embedded on the surface of a two-dimension (2D) N-GQD sheet of ca.35 nm. It is demonstrated that different photoluminescence (PL) could be tuned easily, and the novel multidimensional structure displays excellent performance toward oxygen reduction reaction in alkaline solutions. Thus, the fabricated N-GQD hybrids show bright perspective in biomedical imaging, biosensors, and conversion and storage of energy. PMID:23532722

  4. Conversion of carbon dioxide to resorcylic acid under ultrasonication by Kolbe-Schmitt reaction.

    PubMed

    Shanthi, B; Palanivelu, K

    2015-11-01

    The present work focuses on a new approach for the synthesis of ?-resorcylic acid based on Kolbe-Schmitt reaction using carbon dioxide under ultrasonic and mild condition. The Kolbe-Schmitt reaction is a process for the synthesis of ?-resorcylic acid (2,4-dihydroxybenzoic acid) from resorcinol in aqueous potassium hydroxide solution with gaseous CO2. The influences of carbonation time, flow rate of CO2 and the molar ratio of resorcinol/potassium hydroxide on the yield percentage of resorcylic acid were investigated. The study was assessed with the conventional thermal method (non ultrasonic method) for Kolbe-Schmitt reaction and it was observed that applying ultrasound to save more than 95% and 38.6% energy as shown by energy consumption calculations in bath type and horn type sonicator respectively. ?-Resorcylic acid formed was characterized by (1)H NMR, (13)C NMR, DEPT NMR and FTIR spectroscopy. The amount of CO2 utilized in the reaction was evaluated from the yield percentage of ?-resorcylic acid yield. The maximum yield of resorcylic acid of 30% and 65% was obtained at the resorcinol/potassium hydroxide ratio of 1:3, carbonation time of 150min and the CO2 flow rate of 2L/min in bath type and horn type ultrasonicator, respectively. The applicability of the research work was examined in two different positional isomers of resorcinol under optimum conditions. PMID:26186845

  5. Corrosion resistance of siloxane-poly(methyl methacrylate) hybrid films modified with acetic acid on tin plate substrates: Influence of tetraethoxysilane addition

    NASA Astrophysics Data System (ADS)

    Kunst, S. R.; Cardoso, H. R. P.; Oliveira, C. T.; Santana, J. A.; Sarmento, V. H. V.; Muller, I. L.; Malfatti, C. F.

    2014-04-01

    The aim of this paper is to study the corrosion resistance of hybrid films. Tin plate was coated with a siloxane-poly (methyl methacrylate) (PMMA) hybrid film prepared by sol-gel route with covalent bonds between the organic (PMMA) and inorganic (siloxane) phases obtained by hydrolysis and polycondensation of 3-(trimethoxysilylpropyl) methacrylate (TMSM) and polymerization of methyl methacrylate (MMA) using benzoyl peroxide (BPO) as a thermic initiator. Hydrolysis reactions were catalyzed by acetic acid solution avoiding the use of chlorine or stronger acids in the film preparation. The effect of the addition of tetraethoxysilane (TEOS) on the protective properties of the film was evaluated. The hydrophobicity of the film was determined by contact angle measurements, and the morphology was evaluated by scanning electron microscopy (SEM) and profilometry. The local nanostructure was investigated by Fourier transform infrared spectroscopy (FT-IR). The electrochemical behavior of the films was assessed by open circuit potential monitoring, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements in a 0.05 M NaCl solution. The mechanical behavior was evaluated by tribology. The results highlighted that the siloxane-PMMA hybrid films modified with acetic acid are promising anti-corrosive coatings that acts as an efficient diffusion barrier, protecting tin plates against corrosion. However, the coating properties were affected by the TEOS addition, which contributed for the thickness increase and irregular surface coverage.

  6. Exploring water catalysis in the reaction of thioformic acid with hydroxyl radical: a global reaction route mapping perspective.

    PubMed

    Kaur, Gurpreet; Vikas

    2014-06-12

    Hydrogen abstraction pathways, in the gas-phase reaction of tautomers of thioformic acid (TFA), TFA(thiol), and TFA(thione), with hydroxyl radical in the presence and absence of single water molecule acting as a catalyst, is investigated with high-level quantum mechanical calculations at CCSD(T)/6-311++G(2d,2p)//MP2/6-311++G(2d,2p), CCSD(T)/6-311++G(d,p)//DFT/BHandHLYP/6-311++G(d,p), and DFT/B3LYP/6-311++G(2df,2p) levels of the theory. A systematic and automated search of the potential energy surface (PES) for the reaction pathways is performed using the global reaction route mapping (GRRM) method that employs an uphill walking technique to search prereaction complexes and transition states. The computations reveal significant lowering of the PES and substantial reduction in the activation energy for the hydrogen abstraction pathway in the presence of water, thereby proving water as an efficient catalyst in the reaction of both the TFA tautomers with OH radical. The hydrogen-bonding interactions are observed to be responsible for the large catalytic effect of water. Notably, in the case of TFA(thiol), formyl hydrogen abstraction is observed to be kinetically more favorable, while acidic hydrogen abstraction is observed to be thermodynamically more feasible. Interestingly, in the case of TFA(thione), reaction pathways involving only formyl hydrogen abstraction were observed to be feasible. The water-catalyzed hydrogen abstraction reaction of TFA with hydroxyl radical, investigated in this work, can provide significant insights into the corresponding reaction in the biological systems. PMID:24835635

  7. Kinetics of Acid Reactions: Making Sense of Associated Concepts

    ERIC Educational Resources Information Center

    Tan, Kim Chwee Daniel; Treagust, David F.; Chandrasegaran, A. L.; Mocerino, Mauro

    2010-01-01

    In chemical kinetics, in addition to the concepts related to kinetics, stoichiometry, chemical equilibrium and the characteristics of the reactants are often involved when comparing the rates of different reactions, making such comparisons very challenging for students at all levels, as well as for pre-service science teachers. Consequently, four…

  8. Microwave-assisted reaction of glycosylamine with aspartic acid.

    PubMed

    Real-Fernández, Feliciana; Nuti, Francesca; Bonache, M Angeles; Boccalini, Marco; Chimichi, Stefano; Chelli, Mario; Papini, Anna Maria

    2010-07-01

    The synthesis of N-protected glycosyl amino acids from amines has been investigated and it was found that, under microwave conditions, glycosylamines could be hydrolyzed leading to new products containing a glycosyl ester linkage. The efficiency of the microwave-induced glycosylation of aspartic acid was studied comparing the microwave activity between amide and ester bond formation. Different sugar moieties have been employed to demonstrate the simple and reproducible coupling methodology. New glycosyl ester compounds were further characterized by NMR spectroscopy. PMID:20130939

  9. Reactions Between Water Soluble Organic Acids and Nitrates in Atmospheric Aerosols: Recycling of Nitric Acid and Formation of Organic Salts

    SciTech Connect

    Wang, Bingbing; Laskin, Alexander

    2014-03-25

    Atmospheric particles often include a complex mixture of nitrate and secondary organic materials accumulated within the same individual particles. Nitrate as an important inorganic component can be chemically formed in the atmosphere. For instance, formation of sodium nitrate (NaNO3) and calcium nitrate Ca(NO3)2 when nitrogen oxide and nitric acid (HNO3) species react with sea salt and calcite, respectively. Organic acids contribute a significant fraction of photochemically formed secondary organics that can condense on the preexisting nitrate-containing particles. Here, we present a systematic microanalysis study on chemical composition of laboratory generated particles composed of water soluble organic acids and nitrates (i.e. NaNO3 and Ca(NO3)2) investigated using computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and Fourier transform infrared micro-spectroscopy (micro-FTIR). The results show that water-soluble organic acids can react with nitrates releasing gaseous HNO3 during dehydration process. These reactions are attributed to acid displacement of nitrate with weak organic acids driven by the evaporation of HNO3 into gas phase due to its relatively high volatility. The reactions result in significant nitrate depletion and formation of organic salts in mixed organic acids/nitrate particles that in turn may affect their physical and chemical properties relevant to atmospheric environment and climate. Airborne nitrate concentrations are estimated by thermodynamic calculations corresponding to various nitrate depletions in selected organic acids of atmospheric relevance. The results indicate a potential mechanism of HNO3 recycling, which may further affect concentrations of gas- and aerosol-phase species in the atmosphere and the heterogeneous reaction chemistry between them.

  10. Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications.

    PubMed

    Kristensen, Tor E

    2015-01-01

    Amino acids, whether natural, semisynthetic or synthetic, are among the most important and useful chiral building blocks available for organic chemical synthesis. In principle, they can function as inexpensive, chiral and densely functionalized starting materials. On the other hand, the use of amino acid starting materials routinely necessitates protective group chemistry, and in reality, large-scale preparations of even the simplest side-chain derivatives of many amino acids often become annoyingly strenuous due to the necessity of employing protecting groups, on one or more of the amino acid functionalities, during the synthetic sequence. However, in the case of hydroxyamino acids such as hydroxyproline, serine, threonine, tyrosine and 3,4-dihydroxyphenylalanine (DOPA), many O-acyl side-chain derivatives are directly accessible via a particularly expedient and scalable method not commonly applied until recently. Direct acylation of unprotected hydroxyamino acids with acyl halides or carboxylic anhydrides under appropriately acidic reaction conditions renders possible chemoselective O-acylation, furnishing the corresponding side-chain esters directly, on multigram-scale, in a single step, and without chromatographic purification. Assuming a certain degree of stability under acidic reaction conditions, the method is also applicable for a number of related compounds, such as various amino alcohols and the thiol-functional amino acid cysteine. While the basic methodology underlying this approach has been known for decades, it has evolved through recent developments connected to amino acid-derived chiral organocatalysts to become a more widely recognized procedure for large-scale preparation of many useful side-chain derivatives of hydroxyamino acids and related compounds. Such derivatives are useful in peptide chemistry and drug development, as amino acid amphiphiles for asymmetric catalysis, and as amino acid acrylic precursors for preparation of catalytically active macromolecular networks in the form of soluble polymers, crosslinked polymer beads or nanoparticulate systems. The objective of the present review is to increase awareness of the existence and convenience of this methodology, assess its competitiveness compared to newer and more elaborate procedures for chemoselective O-acylation reactions, spur its further development, and finally to chronicle the informative, but poorly documented history of its development. PMID:25977719

  11. Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

    PubMed Central

    2015-01-01

    Summary Amino acids, whether natural, semisynthetic or synthetic, are among the most important and useful chiral building blocks available for organic chemical synthesis. In principle, they can function as inexpensive, chiral and densely functionalized starting materials. On the other hand, the use of amino acid starting materials routinely necessitates protective group chemistry, and in reality, large-scale preparations of even the simplest side-chain derivatives of many amino acids often become annoyingly strenuous due to the necessity of employing protecting groups, on one or more of the amino acid functionalities, during the synthetic sequence. However, in the case of hydroxyamino acids such as hydroxyproline, serine, threonine, tyrosine and 3,4-dihydroxyphenylalanine (DOPA), many O-acyl side-chain derivatives are directly accessible via a particularly expedient and scalable method not commonly applied until recently. Direct acylation of unprotected hydroxyamino acids with acyl halides or carboxylic anhydrides under appropriately acidic reaction conditions renders possible chemoselective O-acylation, furnishing the corresponding side-chain esters directly, on multigram-scale, in a single step, and without chromatographic purification. Assuming a certain degree of stability under acidic reaction conditions, the method is also applicable for a number of related compounds, such as various amino alcohols and the thiol-functional amino acid cysteine. While the basic methodology underlying this approach has been known for decades, it has evolved through recent developments connected to amino acid-derived chiral organocatalysts to become a more widely recognized procedure for large-scale preparation of many useful side-chain derivatives of hydroxyamino acids and related compounds. Such derivatives are useful in peptide chemistry and drug development, as amino acid amphiphiles for asymmetric catalysis, and as amino acid acrylic precursors for preparation of catalytically active macromolecular networks in the form of soluble polymers, crosslinked polymer beads or nanoparticulate systems. The objective of the present review is to increase awareness of the existence and convenience of this methodology, assess its competitiveness compared to newer and more elaborate procedures for chemoselective O-acylation reactions, spur its further development, and finally to chronicle the informative, but poorly documented history of its development. PMID:25977719

  12. Hybrid single nanoreactor for in situ SERS monitoring of plasmon-driven and small Au nanoparticles catalyzed reactions.

    PubMed

    Li, Pan; Ma, Bingbing; Yang, Liangbao; Liu, Jinhuai

    2015-07-01

    A hybrid single nanoreactor composed of small Au nanoparticles (NPs) and a long Ag nanowire (NW) with a length of 10 ?m can be conveniently located by optical microscopy, allowing us to monitor by in situ surface enhanced Raman spectroscopy (SERS) the plasmon-driven and small Au NPs catalyzed reactions with high sensitivity and reproducibility. PMID:26087227

  13. Atmospheric chemistry of hydrogen halides: Reactions on ice and in strong acids

    SciTech Connect

    Ravishankara, A.R. [Aeronomy Lab., Boulder, CO (United States)

    1995-12-31

    Reactions of hydrogen halides, HCl, HBr, and HI, in sulfuric acid droplets, ice, and liquid water play important roles in the chemistry of Earth`s atmosphere. The hydrogen halides react with other species such as HOCl, ClONO{sub 2}, BrONO{sub 2}, and HOBr to liberate active halogens, the form that can destroy ozone. The impact of these reactions on the chemistry of the ozone in the atmosphere will be described. Also, a brief discussion of the mechanisms of these reactions will be given. Possible experimental and theoretical investigations that can shed light on these reactions will be pointed out.

  14. Hyaluronic acid skin fillers: Adverse reactions and skin testing

    Microsoft Academic Search

    Nicholas J. Lowe; C. Anne Maxwell; Philippa Lowe; Michael G. Duick; Kishor Shah

    2001-01-01

    Background: Hyaluronic acid (HA) fillers have been proposed as alternatives to other temporary skin fillers, such as bovine collagen, for treating facial skin lines and for providing lip augmentation. Several types of commercial HA fillers are now available in many countries. They include Restylane, which is produced by microbiologic engineering techniques, and Hylaform, which is HA extract derived from rooster

  15. The Thiobarbituric Acid (TBA) Reaction in Foods: A Review

    Microsoft Academic Search

    R. Guillén-Sans; M. Guzmán-Chozas

    1998-01-01

    The wide diffusion of 2-thiobarbituric acid (TBA) in the scientific literature is due to the TBA assay, or TBA test, which has been employed in the determination of autoxidative alterations of fats and oils. Two processes occur in autoxidation, generally: the free radical and the photo-oxidation mechanisms. The better studied is the free radical mechanism. The hydroperoxiepidioxides and bicycloendoperoxides are

  16. Redox Reactions in Wheat Dough as Affected by Ascorbic Acid

    Microsoft Academic Search

    W. Grosch; H. Wieser

    1999-01-01

    Ascorbic acid (AA) is used as bread improver, as its addition to dough causes an increase in loaf volume and an improvement in crumb structure. To explain these effects we review the stereospecificity of the improver action and the properties of ascorbate oxidase and glutathione dehydrogenase and the occurrence of low molecular thiols in flour and their concentration changes during

  17. Acid zeolites as catalysts in organic reactions. Friedel-Crafts reaction of 2-alkylfurans with 3-substituted allylic alcohols

    Microsoft Academic Search

    Felipe Algarra; Avelino Corma; Hermenegildo García; Jaime Primo

    1995-01-01

    Methyl 3-(2-furyl) propanoate (1) and 3-(2-furyl) propyl acetate (3) can be conveniently alkylated with high conversion and selectivity by cinnamyl and crotyl alcohols in the liquid phase at moderate temperatures using acid zeolites of medium and large pore size as heterogeneous catalysts. ZSM-5 zeolite exhibited the highest turnover number for the heteroaromatic alkylation. This reaction was found to be totally

  18. Miniature reaction chamber and devices incorporating same

    DOEpatents

    Mathies, Richard A. (Moraga, CA); Woolley, Adam T. (Albany, CA)

    2000-10-17

    The present invention generally relates to miniaturized devices for carrying out and controlling chemical reactions and analyses. In particular, the present invention provides devices which have miniature temperature controlled reaction chambers for carrying out a variety of synthetic and diagnostic applications, such as PCR amplification, nucleic acid hybridization, chemical labeling, nucleic acid fragmentation and the like.

  19. Room Temperature, Hybrid Sodium-Based Flow Batteries with Multi-Electron Transfer Redox Reactions.

    PubMed

    Shamie, Jack S; Liu, Caihong; Shaw, Leon L; Sprenkle, Vincent L

    2015-01-01

    We introduce a new concept of hybrid Na-based flow batteries (HNFBs) with a molten Na alloy anode in conjunction with a flowing catholyte separated by a solid Na-ion exchange membrane for grid-scale energy storage. Such HNFBs can operate at ambient temperature, allow catholytes to have multiple electron transfer redox reactions per active ion, offer wide selection of catholyte chemistries with multiple active ions to couple with the highly negative Na alloy anode, and enable the use of both aqueous and non-aqueous catholytes. Further, the molten Na alloy anode permits the decoupled design of power and energy since a large volume of the molten Na alloy can be used with a limited ion-exchange membrane size. In this proof-of-concept study, the feasibility of multi-electron transfer redox reactions per active ion and multiple active ions for catholytes has been demonstrated. The critical barriers to mature this new HNFBs have also been explored. PMID:26063629

  20. Image Charge Method for Reaction Fields in a Hybrid Ion-Channel Model

    SciTech Connect

    Xu, Zhenli [Shanghai Jiao Tong University, Shanghai; Cai, Wei [ORNL; Cheng, Xiaolin [ORNL

    2011-01-01

    A multiple-image method is proposed to approximate the reaction-field potential of a source charge inside a finite length cylinder due to the electric polarization of the surrounding membrane and bulk water. When applied to a hybrid ion-channel model, this method allows a fast and accurate treatment of the electrostatic interactions of protein with membrane and solvent. To treat the channel/membrane interface boundary conditions of the electric potential, an optimization approach is used to derive image charges by fitting the reaction-field potential expressed in terms of cylindric harmonics. Meanwhile, additional image charges are introduced to satisfy the boundary conditions at the planar membrane interfaces. In the end, we convert the electrostatic interaction problem in a complex inhomogeneous system of ion channel/membrane/water into one in a homogeneous free space embedded with discrete charges (the source charge and image charges). The accuracy of this method is then validated numerically in calculating the solvation self-energy of a point charge.

  1. Room Temperature, Hybrid Sodium-Based Flow Batteries with Multi-Electron Transfer Redox Reactions

    PubMed Central

    Shamie, Jack S.; Liu, Caihong; Shaw, Leon L.; Sprenkle, Vincent L.

    2015-01-01

    We introduce a new concept of hybrid Na-based flow batteries (HNFBs) with a molten Na alloy anode in conjunction with a flowing catholyte separated by a solid Na-ion exchange membrane for grid-scale energy storage. Such HNFBs can operate at ambient temperature, allow catholytes to have multiple electron transfer redox reactions per active ion, offer wide selection of catholyte chemistries with multiple active ions to couple with the highly negative Na alloy anode, and enable the use of both aqueous and non-aqueous catholytes. Further, the molten Na alloy anode permits the decoupled design of power and energy since a large volume of the molten Na alloy can be used with a limited ion-exchange membrane size. In this proof-of-concept study, the feasibility of multi-electron transfer redox reactions per active ion and multiple active ions for catholytes has been demonstrated. The critical barriers to mature this new HNFBs have also been explored. PMID:26063629

  2. Acid-catalyzed heterogeneous reaction of 3-methyl-2-buten-1-ol with hydrogen peroxide.

    PubMed

    Liu, Qifan; Wang, Weigang; Ge, Maofa

    2015-05-01

    Acid-catalyzed heterogeneous oxidation with hydrogen peroxide (H2O2) has been suggested to be a potential pathway for secondary organic aerosol (SOA) formation from isoprene and its oxidation products. However, knowledge of the chemical mechanism and kinetics for this process is still incomplete. 3-Methyl-2-buten-1-ol (MBO321), an aliphatic alcohol structurally similar to isoprene, is emitted by pine forests and widely used in the manufacturing industries. Herein the uptake of MBO321 into H2SO4-H2O2 mixed solution was investigated using a flow-tube reactor coupled to a mass spectrometer. The reactive uptake coefficients (?) were acquired for the first time and were found to increase rapidly with increasing acid concentration. Corresponding aqueous-phase reactions were performed to further study the mechanism of this acid-catalyzed reaction. MBO321 could convert to 2-methyl-3-buten-2-ol (MBO232) and yield isoprene in acidic media. Organic hydroperoxides (ROOHs) were found to be generated through the acid-catalyzed route, which could undergo a rearrangement reaction and result in the formation of acetone and acetaldehyde. Organosulfates, which have been proposed to be SOA tracer compounds in the atmosphere, were also produced during the oxidation process. These results suggest that the heterogeneous acid-catalyzed reaction of MBO321 with H2O2 may contribute to SOA mass under certain atmospheric conditions. PMID:25968263

  3. Organic Chemistry Jasperse Acid-Base Practice Problems A. Identify each chemical as either an "acid" or a "base" in the following reactions, and

    E-print Network

    Jasperse, Craig P.

    Organic Chemistry Jasperse Acid-Base Practice Problems A. Identify each chemical as either an "acid" or a "base" in the following reactions, and identify "conjugate" relationships. -You should have one acid the More Acidic for Each of the Following Pairs: Single Variable Problems 16. 17. 18. 19. 20. 21. O O O OH

  4. Identification of random nucleic acid sequence aberrations using dual capture probes which hybridize to different chromosome regions

    DOEpatents

    Lucas, Joe N. (San Ramon, CA); Straume, Tore (Tracy, CA); Bogen, Kenneth T. (Walnut Creek, CA)

    1998-01-01

    A method is provided for detecting nucleic acid sequence aberrations using two immobilization steps. According to the method, a nucleic acid sequence aberration is detected by detecting nucleic acid sequences having both a first nucleic acid sequence type (e.g., from a first chromosome) and a second nucleic acid sequence type (e.g., from a second chromosome), the presence of the first and the second nucleic acid sequence type on the same nucleic acid sequence indicating the presence of a nucleic acid sequence aberration. In the method, immobilization of a first hybridization probe is used to isolate a first set of nucleic acids in the sample which contain the first nucleic acid sequence type. Immobilization of a second hybridization probe is then used to isolate a second set of nucleic acids from within the first set of nucleic acids which contain the second nucleic acid sequence type. The second set of nucleic acids are then detected, their presence indicating the presence of a nucleic acid sequence aberration.

  5. Evaluation of Hanford high level waste vitrification chemistry for an NCAW simulant -- FY 1994: Potential exothermic reactions in the presence of formic acid, glycolic acid, and oxalic acid

    SciTech Connect

    Sills, J.A.

    1995-07-01

    A potential for an uncontrollable exothermic reaction between nitrate and organic salts during preparation of a high level waste melter feed has been identified. In order to examine this potential more closely, the thermal behavior of simulated neutralized current acid waste (NCAW) treated with various organic reductants was studied. Differential scanning calorimetry (DSC) measurements were collected on simulated waste samples and their supernates treated with organics. Organic reductants used were formic acid, glycolic acid, and oxalic acid. For comparison, samples of untreated simulant and untreated simulant with added noble metals were tested. When heated, untreated simulant samples both with and without noble metals showed no exothermic behavior. All of the treated waste simulant samples showed exothermic behavior. Onset temperatures of exothermic reactions were 120 C to 210 C. Many onset temperatures, particularly those for formic acid treated samples, are well below 181 C, the estimated maximum steam coil temperature (considered to be a worst case maximum temperature for chemical process tank contents). The enthalpies of the reactions were {minus}180 {times} 10{sup {minus}3} J/Kg supernate ({minus}181 J/g) for the oxalic acid treated simulant supernate to {minus}1,150 {times} 10{sup {minus}3} J/Kg supernate ({minus}1,153 J/g) for the formic acid treated simulant supernate.

  6. Histochemical studies on fatty acid in lymphocyte-mediated immune reaction.

    PubMed Central

    Cyong, J; Okada, H

    1976-01-01

    Generation of fatty acids by cell-mediated immune reactions was demonstrated histochemically by Okamoto's method, which stains fatty acids and their alkaline earth salts red-brown. The red-brown deposits were observed more frequently on the mixed culture of immune lymph node cells of C3H/He and C57Bl/6 mice than on the culture of either of the pair alone. Similar evidence was observed in the reaction of immune lymph node cells with the corresponding allogeneic mouse tumour cells as well as on the immune lumphocytes of guinea-pig incubated in the presence of the soluble antigen PPD. In spite of the findings which indicated a possible generation of fatty acids in the immunological reaction of immune lymphocytes, we failed to demonstrate evidence of fatty acid generation in the ascites during rejection of allogeneic ascitic MM102 tumour cells, although accumulation of neutral lipid was evident. This unexpected contradicition was interpreted by finding that MM102 cells incubated with oleic acid did not contain fatty acid but did contain a remarkable amount of neutral lipid on histochemical examinations. This finding indicated that once generated, fatty acids would be converted to neutral lipid in the ascites where allogeneic tumour cells were rejected. Images Figure 2 Figure 3 Figure 5 Figure 6 PMID:776819

  7. Influence of Monomer Mixing Ratio on Membrane Nanostructure in Interfacial Polycondensation: Application of Hybrid MC/MD Reaction Method with Minimum Bond Convention.

    PubMed

    Suzuki, Yuichi; Koyano, Yoshiyuki; Nagaoka, Masataka

    2015-06-01

    FT-30, a typical aromatic polyamide membrane, is formed by interfacial polycondensation (IP) reaction between m-phenylenediamine (MPD) and benzene 1,3,5-tricarboxylic acid chloride (TMC) monomers. To investigate its microscopic characteristics, we performed an atomistic molecular simulation using the hybrid MC/MD reaction method modified to allow intercellular chemical bonds stretching over the periodic boundaries. Starting with appropriate monomer model systems, we succeeded in making membrane models by simulating a succession of condensation reactions. Through an analysis comparing our calculation results for the degrees of polymer cross-linking (DPC) and the composition ratios to the experimental results, we clarified the MPD/TMC mixing ratios in the near-surface active (NSA) and interior active (IA) regions associated with the reaction mechanism of IP. Further, we executed water diffusion simulations using the membrane model of the IA region and showed the calculated values of the total mass density of the hydrated membrane and the partition coefficient K to be in good agreement with the experimental ones. In conclusion, the present computationally modeled polyamide membrane has sufficient fidelity to the actual membrane and should be considered a stable spatial structure in the local equilibrium state under a nonequilibrium stationary state of permeation. PMID:25973839

  8. Effect of acidic solutions on the surface degradation of a micro-hybrid composite resin.

    PubMed

    Münchow, Eliseu A; Ferreira, Ana Cláudia A; Machado, Raissa M M; Ramos, Tatiana S; Rodrigues-Junior, Sinval A; Zanchi, Cesar H

    2014-01-01

    Composite resins may undergo wear by the action of chemical substances (e.g., saliva, alcohol, bacterial acids) of the oral environment, which may affect the material's structure and surface properties. This study evaluated the effect of acidic substances on the surface properties of a micro-hybrid composite resin (Filtek Z-250). Eighty specimens were prepared, and baseline hardness and surface roughness (KMN0 and Ra0, respectively) were measured. The specimens were subjected to sorption (SO) and solubility (SL) tests according to ISO 4049:2009, but using different storage solutions: deionized water; 75/25 vol% ethanol/water solution; lactic acid; propionic acid; and acetic acid. The acids were used in two concentrations: PA and 0.02 N. pH was measured for all solutions and final hardness (KMN1) and surface roughness (Ra1) were measured. Data were analyzed with paired t-tests and one-way ANOVA and Tukey's test (a=5%). All solutions decreased hardness and increased the Ra values, except for the specimens stored in water and 0.02 N lactic acid, which maintained the hardness. All solutions produced similar SO and SL phenomena, except for the 0.02 N lactic acid, which caused lower solubility than the other solutions. Ethanol showed the highest pH (6.6) and the 0.02 N lactic acid the lowest one (2.5). The solutions affected negatively the surface properties of the composite resin; in addition, an acidic pH did not seem to be a significant factor that intensifies the surface degradation phenomena. PMID:25250496

  9. Investigation and application of multiple reactions between molybdoniobium heteropoly acid and di- or trimethylthionines

    SciTech Connect

    Mirzoyam, F.B.; Karapetyan, A.A.

    1986-03-01

    This paper presents the results of the study and use of reactions of molybdoniobic acid (MNA) with di- and trimethylthiones (DMT and TMT, respectively). It was found that light absorption of acetone solutions of the products of outer-sphere interaction between MNA and DMT or TMT enabled the determination of optimum acidity for MNA formation. Reaction between TMT and MNA gives two different compounds containing two and five associated dye cations, different in molar extinction coefficient and optimum reaction acidity (pH 0.05-0.25 and 0.35-0.90). Formation of the 6th and 8th molybdenum series with an identical composition of the outer sphere is shown. A highly sensitive photometric method for determining niobium has been developed.

  10. Characterization of the esterification reaction in high free fatty acid oils

    NASA Astrophysics Data System (ADS)

    Altic, Lucas Eli Porter

    Energy and vegetable oil prices have caused many biodiesel producers to turn to waste cooking oils as feedstocks. These oils contain high levels of free fatty acids (FFAs) which make them difficult or impossible to convert to biodiesel by conventional production methods. Esterification is required for ultra-high FFA feedstocks such as Brown Grease. In addition, ultrasonic irradiation has the potential to improve the kinetics of the esterification reaction. 2-level, multi-factor DOE experiments were conducted to characterize the esterification reaction in ultra-high FFA oils as well as determine whether ultrasonic irradiation gives any benefit besides energy input. The study determined that sulfuric acid content had the greatest effect followed by temperature and water content (inhibited reaction). Methanol content had no effect in the range studied. A small interaction term existed between sulfuric acid and temperature. The study also concluded that sonication did not give any additional benefit over energy input.

  11. Theoretical stusy of the reaction between 2,2',4' - trihydroxyazobenzene-5-sulfonic acid and zirconium

    USGS Publications Warehouse

    Fletcher, Mary H.

    1960-01-01

    Zirconium reacts with 2,2',4'-trihydroxyazobenzene-5-sulfonic acid in acid solutions to Form two complexes in which the ratios of dye to zirconium are 1 to 1 and 2 to 1. Both complexes are true chelates, with zirconium acting as a bridge between the two orthohydroxy dye groups. Apparent equilibrium constants for the reactions to form each of the complexes are determined. The reactions are used as a basis for the determination of the active component in the dye and a graphical method for the determination of reagent purity is described. Four absorption spectra covering the wave length region from 350 to 750 mu are given, which completely define the color system associated with the reactions in solutions where the hydrochloric acid concentration ranges from 0.0064N to about 7N.

  12. An Investigation of Solid-State Amidization and Imidization Reactions in Vapor Deposited Poly (amic acid)

    SciTech Connect

    Anthamatten, M; Letts, S A; Day, K; Cook, R C; Gies, A P; Hamilton, T P; Nonidez, W K

    2004-06-28

    The condensation polymerization reaction of 4,4'-oxydianiline (ODA) with pyromellitic dianhydride (PMDA) to form poly(amic acid) and the subsequent imidization reaction to form polyimide were investigated for films prepared using vapor deposition polymerization techniques. Fourier-transform infrared spectroscopy (FT-IR), thermal analysis, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of films at different temperatures indicate that additional solid-state polymerization occurs prior to imidization reactions. Experiments reveal that, upon vapor deposition, poly(amic acid) oligomers form that have a number-average molecular weight of about 1500 Daltons. Between 100 - 130 C these chains undergo additional condensation reaction to form slightly higher molecular weight oligomers. Calorimetry measurements show that this reaction is exothermic ({Delta}H {approx} -30 J/g) with an activation energy of about 120 kJ/mol. Experimental reaction enthalpies are compared to results from ab initio molecular modeling calculations to estimate the number of amide groups formed. At higher temperatures (150 - 300 C) imidization of amide linkages occurs as an endothermic reaction ({Delta}H {approx} +120 J/g) with an activation energy of about 130 kJ/mol. Solid-state kinetics were found to depend on reaction conversion as well as the processing conditions used to deposit films.

  13. Label-free potentiometry for detecting DNA hybridization using peptide nucleic acid and DNA probes.

    PubMed

    Goda, Tatsuro; Singi, Ankit Balram; Maeda, Yasuhiro; Matsumoto, Akira; Torimura, Masaki; Aoki, Hiroshi; Miyahara, Yuji

    2013-01-01

    Peptide nucleic acid (PNA) has outstanding affinity over DNA for complementary nucleic acid sequences by forming a PNA-DNA heterodimer upon hybridization via Watson-Crick base-pairing. To verify whether PNA probes on an electrode surface enhance sensitivity for potentiometric DNA detection or not, we conducted a comparative study on the hybridization of PNA and DNA probes on the surface of a 10-channel gold electrodes microarray. Changes in the charge density as a result of hybridization at the solution/electrode interface on the self-assembled monolayer (SAM)-formed microelectrodes were directly transformed into potentiometric signals using a high input impedance electrometer. The charge readout allows label-free, reagent-less, and multi-parallel detection of target oligonucleotides without any optical assistance. The differences in the probe lengths between 15- to 22-mer dramatically influenced on the sensitivity of the PNA and DNA sensors. Molecular type of the capturing probe did not affect the degree of potential shift. Theoretical model for charged rod-like duplex using the Gouy-Chapman equation indicates the dominant effect of electrostatic attractive forces between anionic DNA and underlying electrode at the electrolyte/electrode interface in the potentiometry. PMID:23435052

  14. Synthesis and structural characterization of sialic acid-glutamic acid hybrid foldamers as conformational surrogates of alpha-2,8-linked polysialic acid.

    PubMed

    Saludes, Jonel P; Ames, James B; Gervay-Hague, Jacquelyn

    2009-04-22

    Surface expression of alpha-(2,8)-linked polymers of sialic acid in adult tissues has been correlated with metastasis of several human cancers. One approach to chemotherapeutic intervention against the spread of these cancers involves the development of immunogenic molecules that elicit an antibody response against alpha-(2,8)-linked polysialic acids. Naturally occurring polysialic acids are not viable candidates because they are present during embryonic development and are recognized as self by the immune system. These natural polymers also have poor pharmacokinetic properties because they are readily degraded by neuraminidase enzymes. We have been interested in developing structural surrogates of polysialic acids in an effort to overcome these limitations. Reported herein are microwave-assisted solid-phase peptide syntheses and structural characterization studies of a series of alpha/delta hybrid peptides derived from Fmoc-Neu2en and Fmoc-Glu(OtBu)-OH. Conformational experiments including circular dichroism, NH/ND exchange, and ROESY in aqueous solution were performed to study the secondary structures of these hybrid foldamers. ROESY data were analyzed with the assistance of XPLOR-NIH that was modified to include parameter and topology files to accommodate unnatural amino acids and the delta amide linkages. The results indicate that stable secondary structure is dependent upon both the amino acid sequence and the configuration of Glu. The most stable foldamer was composed of a total of 6 residues beginning with L-Glu at the carboxy terminus and alternating Neu2en and L-Glu residues. In water, this foldamer adopts a right-handed helical conformation with 3.7 residues per turn, 7.4 A pitch, 5.8 A diameter, and a length of 18.5 A, which is stabilized by both classical C=O...H-N backbone interactions and by pyranose ring O and L-Glu HN H-bonding. These structural features orient the L-Glu carboxylates along the helical backbone with a periodicity that matches the carboxylate positions along the reported G2(+) left-handed helix of alpha-(2,8)-polysialic acid. However, the charge density of the foldamer is one-half that of the natural polymer. These findings provide a fundamental understanding of the factors that influence stable secondary structure in hybrid Neu2en/Glu systems, and the tools we have developed establish a viable platform for the rational design of alpha-(2,8)-polysialic acid surrogates. PMID:19323529

  15. Coupling reactions of alpha-bromoalkenyl phosphonates with aryl boronic acids and alkenyl borates.

    PubMed

    Kobayashi, Yuichi; William, Anthony D

    2002-11-28

    [reaction: see text] Transition metal-catalyzed arylation and alkenylation of the alpha-bromoalkenyl phosphonates were investigated with organoboranes and -borates. Arylation was successful with the aryl boronic acids and a palladium catalyst, while alkenylation was found to proceed with alkenyl borates and a nickel catalyst. In addition, an intramolecular Diels-Alder reaction of the diene prepared by the alkenylation afforded the corresponding adduct. PMID:12443068

  16. The first dehydration and the competing reaction pathways of glucose homogeneously and heterogeneously catalyzed by acids.

    PubMed

    Lin, Xufeng; Qu, Yuanyuan; Lv, Yanhong; Xi, Yanyan; Phillips, David Lee; Liu, Chenguang

    2013-02-28

    The dehydration mechanisms for glucose in ?-pyranose (BP) and in open-chain (OC) forms, catalyzed by acids homogeneously and heterogeneously, were investigated using density functional and two-layer ONIOM calculations. The first dehydration reaction and competing reaction pathways are the main focus of the present study. The energetics of five dehydration and two isomerization pathways were examined for the protonated form of BP in acidic aqueous solutions and the most favorable pathway of these was found to be the dehydration at the anomeric site. No dehydration pathway of OC glucose is favored over its isomerization to BP or to fructose. The relative ease of dehydration over isomerization depends on the selection of the reaction media for the protonated form of BP. These two reaction pathways catalyzed by a surface Brönsted acid site were then examined and the isomerization pathway was found to be more favorable than dehydration at the anomeric site on a surface acid site. These mechanistic insights provide an important guide for the catalyst design/selection of the reaction media for glucose dehydration. PMID:23340797

  17. Coupling of hydrologic transport and chemical reactions in a stream affected by acid mine drainage

    USGS Publications Warehouse

    Kimball, B.A.; Broshears, R.E.; Bencala, K.E.; McKnight, D.M.

    1994-01-01

    Experiments in St. Kevin Gulch, an acid mine drainage stream, examined the coupling of hydrologic transport to chemical reactions affecting metal concentrations. Injection of LiCl as a conservative tracer was used to determine discharge and residence time along a 1497-m reach. Transport of metals downstream from inflows of acidic, metal-rich water was evaluated based on synoptic samples of metal concentrations and the hydrologic characteristics of the stream. Transport of SO4 and Mn was generally conservative, but in the subreaches most affected by acidic inflows, transport was reactive. Both 0.1-??m filtered and particulate Fe were reactive over most of the stream reach. Filtered Al partitioned to the particulate phase in response to high instream concentrations. Simulations that accounted for the removal of SO4, Mn, Fe, and Al with first-order reactions reproduced the steady-state profiles. The calculated rate constants for net removal used in the simulations embody several processes that occur on a stream-reach scale. The comparison between rates of hydrologie transport and chemical reactions indicates that reactions are only important over short distances in the stream near the acidic inflows, where reactions occur on a comparable time scale with hydrologic transport and thus affect metal concentrations.

  18. The Reaction of Piperazine2,5-dione with 2-Formylbenzoic Acid

    Microsoft Academic Search

    Margaret L. Baron; Ian D. Rae; Peta M. Simmonds

    Reaction of piperazine-2,5-dione with 2-formylbenzoic acid in the presence of triethylamine gives three products: 1-(3'-oxo-1',3'-dihydroisobenzofuran-l'-yl)piperazine-2,5-dione, its 1,4-bis analogue which had previously been identified as the 3,6-compound, and 2,2'-(3,6-dioxopiperazine-2,5-diylidene- bis(methylidyne))bis(benzoic acid). The latter compound is shown by 'H and 13C n.m.r, spectroscopy to be the Z,Z isomer. From the reaction of piperazine-2,5-dione with 2-formylbenzoic we have isolated three products. The first

  19. Direct observation of NH2* reactions with oxygen, amino acids, and melanins.

    PubMed

    Clarke, K; Edge, R; Johnson, V; Land, E J; Navaratnam, S; Truscott, T G

    2008-02-14

    We report the direct observation of the quenching of the weakly absorbing transient due to the amino radical by oxygen and, hence determine, by a totally direct method, the corresponding rate constant (k = (1.1 +/- 0.1) x 10(9) dm3 mol(-1) s(-1)). We also report the rate constants for the reactions of the amino radical with several amino acids and models of black eumelanin and blond/red phaeomelanin. These reactions lead to a mechanism, based on free radicals, that can explain why ammonia is useful in commercial hair (melanin) bleaching, avoiding excessive amino acid (hair protein) damage. PMID:18215026

  20. Mechanism and stoichiometry of the redox reaction between iron(III) and caffeic acid

    Microsoft Academic Search

    S. Deiana; C. Gessa; B. Manunza; M. Marchetti; M. Usai

    1992-01-01

    The stoichiometry of the redox reaction of caffeic acid with iron(III) was determined at pH 2.5. A linear increase in the\\u000a yield of iron(II) was found with increasing iron(III) concentration until reached constant values when iron(III)\\/caffeic acid\\u000a molar ratios were higher than 9. The reaction proceeds through two steps each having different rates, and involving intermediates\\u000a with different redox activities.

  1. Electrical detection of hybridization and threading intercalation of deoxyribonucleic acid using carbon nanotube network field-effect

    E-print Network

    Rogers, John A.

    Electrical detection of hybridization and threading intercalation of deoxyribonucleic acid using carbon nanotube network field-effect transistors Ee-Ling Gui, Lain-Jong Li,a P. S. Lee, Anup Lohani deoxyribonucleic acid DNA sensing characteristics of carbon nanotube network field-effect transistors CNNFETs

  2. Kinetics of the reaction of peracetic acid with naphthalene and anisol

    Microsoft Academic Search

    A. A. Akhrem; P. A. Kiselev; D. E. Metelitza

    1975-01-01

    The kinetics of the bimolecular reaction of peracetic acid with naphthalene (58–75 °C) and anisol (37.5–50.5 °C) have been studied in 2?1 dichlorethane-acetic acid. The rate constans for naphthalene and anisol are Knapht=2.0×109 exp (?21000\\/RT) 1 mol?1 sec?1, Kanis=6.3×108 exp (?17000\\/RT) 1 mol?1 sec?1.

  3. Gas phase proton transfer reaction of nitric acid-ammonia and the role of water

    Microsoft Academic Search

    Fu-Ming Tao

    1998-01-01

    The gas-phase proton transfer reaction of nitric acid-ammonia and the effect of the first three water molecules are investigated by high level ab initio calculations on the molecular clusters HNO3-NH3-(H2O)n, n=0,1,2,3. The equilibrium structures, binding energies, and harmonic frequencies of the clusters as well as the potential energy surfaces along the proton transfer pathway of nitric acid-ammonia are calculated at

  4. Bifunctional ligands in combination with phosphines and Lewis acidic phospheniums for the carbonylative Sonogashira reaction.

    PubMed

    Tan, Chen; Wang, Peng; Liu, Huan; Zhao, Xiao-Li; Lu, Yong; Liu, Ye

    2015-06-23

    The combination of phosphine-ligated Pd catalysis and phosphenium(v) Lewis acid catalysis has been developed for the carbonylative Sonogashira reaction using phosphino-phosphenium salts () as bifunctional ligands, in which the Lewis acidic phosphenium(v) cations can form secondary bonds with O atoms (in C[double bond, length as m-dash]O) to cooperatively stabilize Pd-acyl intermediates. PMID:26055388

  5. Coupling of Hydrologic Transport and Chemical Reactions in a Stream Affected by Acid Mine Drainage

    Microsoft Academic Search

    Briant A. Kimball; Robert E. Broshears; Kenneth E. Bencala; Diane M. McKnight

    1994-01-01

    ~~~~~ ~ Experiments in St. Kevin Gulch, an acid mine drainage stream, examined the coupling of hydrologic transport to chemical reactions affecting metal concentrations. Injec- tion of LiCl as a conservative tracer was used to determine discharge and residence time along a 1497-m reach. Transport of metals downstream from inflows of acidic, metal-rich water was evaluated based on synoptic samples

  6. Effect of Y- Zeolite Acidity on 1,2,4 Tri Methyl Benzenes Reactions

    Microsoft Academic Search

    S. Al-Khattaf

    Catalytic transformation of 1,2,4-trimethyl benzene has been investigated over two different USY zeolite based catalysts in a novel riser simulator at different operating conditions. FCC-SY catalyst has low acidity and FCC-CY contains high acidity. The effect of reaction conditions on the variation of isomerization to disproportionation products ratio (I\\/D), distribution of trimethylbenzene (TMB) isomers (1,3,5-to-1,2,3-) and values of p-xylene\\/o- xylene

  7. ?-Amido sulfones from natural ?-amino acids and their reaction with carbon nucleophiles

    Microsoft Academic Search

    Marino Petrini; Mirko Seri

    2006-01-01

    Amides obtained from N-carbamoyl ?-amino acids react with aldehydes in the presence of benzenesulfinic acid to give ?-amido sulfones in good yield. These derivatives act as equivalents of N-acylimines in the reaction with nucleophiles leading to the corresponding addition products. The utilization of the lithium enolate of alkyl acetates as a nucleophile allows the preparation of ?,?-dipeptides, while a two-step

  8. SYNTHESES WITH SULFUR CONTAINING NUCLEOPHILES. I. REACTION OF SULFINIC ACIDS WITH 2-HALOGENO-2-NITROETHENYLARENES

    Microsoft Academic Search

    D. I. Aleksiev; S. Ivanova

    1995-01-01

    The interaction between unsubstituted and p-substituted benzenesulfinic acids and various 2-halogeno-2-nitroethenylarenes at mol ratios sulfinic acid:2-halogeno-2-nitroethenylarene = 1:1 and 2:1 was studied at 0°C and 20°C for 16 and 96 hours. It was proved that, depending on experimental conditions, the reaction results not only in ?-halogeno-?-nitro-?-sulfones but also in ?-nitro-?,?-disulfones, which are obtained by a consecutive process. The quantitative ratio

  9. Hybrid poly(lactic-co-glycolic acid) nanoparticles: design and delivery prospectives.

    PubMed

    Pandita, Deepti; Kumar, Sandeep; Lather, Viney

    2015-01-01

    Poly(lactic-co-glycolic acid) (PLGA), a US Food and Drug Administration (FDA)-approved copolymer, has been exploited widely in the design of nanoparticles because it is biodegradable, biocompatible, protects the drug molecules from degradation, and aids in producing sustained and targeted delivery. However, certain constraints associated with PLGA nanoparticles, such as poor drug encapsulation, polymer degradation, and scale-up issues, have led to the development of emerging hybrid PLGA delivery systems. These hybrid nanoparticles are core-shell nanostructures comprising either a PLGA core or a PLGA shell combining multiple functionalities within one system and, thus, exhibiting the complementary characteristics of two different platforms used for the delivery of a wide range of therapeutics and imaging. PMID:25277320

  10. Hybrid gels assembled from Fmoc-amino acid and graphene oxide with controllable properties.

    PubMed

    Xing, Pengyao; Chu, Xiaoxiao; Li, Shangyang; Ma, Mingfang; Hao, Aiyou

    2014-08-01

    A supramolecular gel is obtained from the self-assembly of an ultralow-molecular-weight gelator (N-fluorenyl-9-methoxycarbonyl glutamic acid) in good and poor solvents. The gelators can self-assemble into a lamellar structure, which can further form twisted fibers and nanotubes in the gel phase. Rheological studies show that the gels are robust and rigid, and are able to rapidly self-recover to a gel after being destroyed by shear force. Fluorescence experiments reveal the aggregation-induced emission effects of the gel system; the fluorescence intensity is significantly enhanced by gel formation. Graphene oxide (GO) is introduced into the system efficiently to give a hybrid material, and the interaction between gelators-GO sheets is studied. Rheological and fluorescent studies imply that the mechanical properties and the fluorescent emission of the hybrid materials can be fine-tuned by controlling the addition of GO. PMID:24789749

  11. Sulfonic and phosphonic acid and bifunctional organic-inorganic hybrid membranes and their proton conduction properties.

    PubMed

    Sel, Ozlem; Azais, Thierry; Maréchal, Manuel; Gébel, Gérard; Laberty-Robert, Christel; Sanchez, Clément

    2011-11-01

    Hybrid organic-inorganic approaches are used for the synthesis of bifunctional proton exchange membrane fuel cell (PEMFC) membranes owing to their ability to combine the properties of a functionalized inorganic network and an organic thermostable polymer. We report the synthesis of both sulfonic and phosphonic acid functionalized mesostructured silica networks into a poly(vinylidenefluoride-co-hexafluoropropylene) (poly(VDF-co-HFP) copolymer. These membranes, containing different amounts of phosphonic acid and sulfonic acid groups, have been characterized using FTIR and NMR spectroscopy, SA-XRD, SAXS, and electrochemical techniques. The proton conductivity of the bifunctional hybrid membranes depends strongly on hydration, increasing by two orders of magnitude over the relative humidity (RH) range of 20 to 100%, up to a maximum of 0.031 S cm(-1) at 60 °C and 100% RH. This value is interesting as only half of the membrane conducts protons. This approach allows the synthesis of a porous SiO(2) network with two different functions, having -SO(3)H and -PO(3)H(2) embedded in a thermostable polymer matrix. PMID:21850711

  12. Enhancing the specificity and efficiency of polymerase chain reaction using polyethyleneimine-based derivatives and hybrid nanocomposites

    PubMed Central

    Tong, Weiwei; Cao, Xueyan; Wen, Shihui; Guo, Rui; Shen, Mingwu; Wang, Jianhua; Shi, Xiangyang

    2012-01-01

    There is a general necessity to improve the specificity and efficiency of the polymerase chain reaction (PCR), and exploring the PCR-enhancing mechanism still remains a great challenge. In this paper we report the use of branched polyethyleneimine (PEI)-based derivatives and hybrid nanocomposites as a novel class of enhancers to improve the specificity and efficiency of a nonspecific PCR system. We show that the surface-charge polarity of PEI and PEI derivatives plays a major role in their effectiveness to enhance the PCR. Positively charged amine-terminated pristine PEI, partially (50%) acetylated PEI (PEI-Ac50), and completely acetylated PEI (PEI-Ac) are able to improve PCR efficiency and specificity with an optimum concentration order of PEI < PEI-Ac50 < PEI-Ac, whereas negatively charged carboxyl-terminated PEI (PEI-SAH; SAH denotes succinamic acid groups) and neutralized PEI modified with both polyethylene glycol (PEG) and acetyl (Ac) groups (PEI-PEG-Ac) are unable to improve PCR specificity and efficiency even at concentrations three orders of magnitude higher than that of PEI. Our data clearly suggests that the PCR-enhancing effect is primarily based on the interaction between the PCR components and the PEI derivatives, where electrostatic interaction plays a major role in concentrating the PCR components locally on the backbones of the branched PEI. In addition, multiwalled carbon nanotubes modified with PEI and PEI-stabilized gold nanoparticles are also able to improve the PCR specificity and efficiency with an optimum PEI concentration less than that of the PEI alone, indicating that the inorganic component of the nanocomposites may help improve the interaction between PEI and the PCR components. The developed PEI-based derivatives or nanocomposites may be used as efficient additives to enhance other PCR systems for different biomedical applications. PMID:22393296

  13. The reaction of hyaluronic acid and its monomers, glucuronic acid and N-acetylglucosamine, with reactive oxygen species

    Microsoft Academic Search

    Michael Jahn; John W Baynes; Gerhard Spiteller

    1999-01-01

    Synovial fluid is a ?0.15% (w\\/v) aqueous solution of hyaluronic acid (HA), a polysaccharide consisting of alternating units of GlcA and GlcNAc. In synovial fluid of patients suffering from rheumatoid arthritis, HA is thought to be degraded either by radicals generated by Fenton chemistry (Fe2+\\/H2O2) or by NaOCl generated by myeloperoxidase. We investigated the course of model reactions of these

  14. Correlation of ribonucleic acid polymerase chain reaction, acid dissociated p24 antigen, and neopterin with progression of disease

    Microsoft Academic Search

    Daniela Zaknun; John Orav; Janet Kornegay; Inas Al-Attar; Dietmar Fuchs; John Zaknun; Helmut Wachter; Pamela Chatis; Sandra K. Burchett; Kenneth McIntosh

    1997-01-01

    Objective: We investigated the relationship between cell-free viral load, neopterin, age-adjusted CD4 + cell concentration, and clinical events in 49 children with vertically acquired human immunodeficiency virus type 1 infection.Study design: Viral load was measured by quantitating viral ribonucleic acid in serum by polymerase chain reaction and measurement of immune complex dissociated p24 antigen in serum and plasma. Children were

  15. Application of peptide nucleic acid to the direct detection of deoxyribonucleic acid amplified by polymerase chain reaction

    Microsoft Academic Search

    Shinya Sawata; Eriko Kai; Kazunori Ikebukuro; Tetsuya Iida; Takeshi Honda; Isao Karube

    1999-01-01

    Double-stranded DNA amplified by polymerase chain reaction (PCR) was detected by peptide nucleic acid (PNA) using a BIAcore™ 2000 biosensor based on surface plasmon resonance (SPR). PNA is an artificial oligo amide that is capable of forming highly stable complexes with complementary oligonucleotides. We succeeded in the direct detection of double-stranded DNA, amplified by PCR with high-sequence specificity. It was

  16. Immersed effects of Ta and Zr compounds on activity of oxygen reduction reaction in sulfuric acid

    NASA Astrophysics Data System (ADS)

    Matsuzawa, Koichi; Nozawa, Kazuhiro; Yamauchi, Kyosuke; Ishihara, Akimitsu; Mitsushima, Shigenori; Ota, Ken-ichiro

    2013-03-01

    The immersed effects of Ta and Zr compounds (Ta-CNO and Zr-CNO) on the activity of oxygen reduction reaction (ORR) have been investigated in the sulfuric acid. The concentration of Zr on Zr-CNO was higher than that of Pt on Pt black. The concentration of Ta on Ta-CNO was almost the same as that of Pt on Pt black in sulfuric acid. The catalytic activity of Zr-CNO for the ORR decreased with time. In contrast, the catalytic activity of Ta-CNO for the ORR was maintained up to 1050 h in the sulfuric acid.

  17. Chiral Brønsted Acid as a True Catalyst: Asymmetric Mukaiyama Aldol and Hosomi-Sakurai Allylation Reactions.

    PubMed

    Sai, Masahiro; Yamamoto, Hisashi

    2015-06-10

    Highly diastereo- and enantioselective Mukaiyama aldol reaction catalyzed by a new chiral Brønsted acid, N-(perfluorooctanesulfonyl)thiophosphoramide, is described. The perfluorooctyl substituent on the sulfonyl group of the catalyst plays an essential role in the stereoselection. The catalyst also allows the asymmetric Hosomi-Sakurai allylation, which has been considerably challenging due to the low reactivity of allylsilanes. (29)Si and (31)P NMR monitoring reveals the characteristic feature of the thiophosphoramide catalyst, acting as a strong Brønsted acid even in the presence of excess silyl nucleophiles, which cannot be found in other related phosphoric acid analogues. PMID:26017677

  18. Kinetic resolution of acids in acylation reactions in the presence of chiral tertiary amines

    SciTech Connect

    Potapov, V.M.; Dem'yanovich, V.M.; Khlebnikov, V.A.

    1988-07-10

    Asymmetric synthesis has now become an important method for the production of optically active compounds, and its most attractive form is asymmetric catalysis. This work was devoted to an investigation into asymmetric catalysis with chiral tertiary amines in acylation reactions. During the acylation of alcohols and amines by the action of racemic 2-phenylpropionic and 2-methyl-3-phenylpropionic acids in the presence of S-nicotine the initial acids are resolved kinetically. The (R)-2-phenylpropionic acid obtained in this way had an optical purity of 0.5-1.5%.

  19. DNA surface hybridization regimes.

    PubMed

    Gong, Ping; Levicky, Rastislav

    2008-04-01

    Surface hybridization reactions, in which sequence-specific recognition occurs between immobilized and solution nucleic acids, are routinely carried out to quantify and interpret genomic information. Although hybridization is fairly well understood in bulk solution, the greater complexity of an interfacial environment presents new challenges to a fundamental understanding, and hence application, of these assays. At a surface, molecular interactions are amplified by the two-dimensional nature of the immobilized layer, which focuses the nucleic acid charge and concentration to levels not encountered in solution, and which impacts the hybridization behavior in unique ways. This study finds that, at low ionic strengths, an electrostatic balance between the concentration of immobilized oligonucleotide charge and solution ionic strength governs the onset of hybridization. As ionic strength increases, the importance of electrostatics diminishes and the hybridization behavior becomes more complex. Suppression of hybridization affinity constants relative to solution values, and their weakened dependence on the concentration of DNA counterions, indicate that the immobilized strands form complexes that compete with hybridization to analyte strands. Moreover, an unusual regime is observed in which the surface coverage of immobilized oligonucleotides does not significantly influence the hybridization behavior, despite physical closeness and hence compulsory interactions between sites. These results are interpreted and summarized in a diagram of hybridization regimes that maps specific behaviors to experimental ranges of ionic strength and probe coverage. PMID:18381819

  20. Polycarboxylic acids as network modifiers for water durability improvement of inorganic-organic hybrid tin-silico-phosphate low-melting glasses

    SciTech Connect

    Menaa, Bouzid [Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan) and PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama (Japan)]. E-mail: bouzidmenaa@noncry.kuicr.kyoto-u.ac.jp; Mizuno, Megumi [Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Takahashi, Masahide [Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan) and PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama (Japan)]. E-mail: masahide@noncry.kuicr.kyoto-u.ac.jp; Tokuda, Yomei [Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Yoko, Toshinobu [Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

    2006-02-15

    We investigated the water durability of the inorganic-organic hybrid tin-silico-phosphate glasses Me{sub 2}SiO-SnO-P{sub 2}O{sub 5} (Me designs the organic methyl group) doped with organic acids (salicylic acid (SA), tartaric acid (TA), citric acid (Canada) and butane tetracarboxylic acid (BTCA)) containing one or more of carboxylic groups per molecule. The structure, thermal properties and durability of the final glasses obtained via a non-aqueous acid-base reaction were discussed owing to the nature and the concentration of the acid added. {sup 29}Si magic angle spinning (MAS) NMR and {sup 31}P MAS NMR spectra, respectively, showed clearly a modification of the network in the host glass matrix of the Me{sub 2}SiO-SnO-P{sub 2}O{sub 5} system. The polycondensation enhancement to form -P-O-Si-O-P- linkages (PSP) and the increase of the Q {sup 2} unit (two bridging oxygens per phosphorus atom) over the Q {sup 3} unit (three bridging oxygens per phosphorus atom) as a function of the acid in the order SAacids containing a large number of carboxylic groups per molecule. The presence of carboxylic groups of the acid acting as network modifier may retard the movement of water molecules through the glasses due to the steric hindrance strengthening the PSP connections in a chain-like structure.

  1. Hybrid Quantum Mechanics/Molecular Mechanics-Based Molecular Dynamics Simulation of Acid-Catalyzed Dehydration of Polyols in Liquid Water

    SciTech Connect

    Caratzoulas, Stavros [Catalysis Center for Energy Innovation, Univ. of Delaware, Newark, DE (United States); Courtney, Timothy [Univ. of Delaware, Newark, DE (United States); Vlachos, Dionisios G. [Catalysis Center for Energy Innovation, Univ. of Delaware, Newark, DE (United States)

    2011-08-18

    We use the conversion of protonated glycerol to acrolein for a case study of the mechanism of acid-catalyzed dehydration of polyols in aqueous environments. We employ hybrid Quamtum Mechanics/Molecular Mechanics Molecular Dynamics (QM/MM MD) simulations with biased sampling and perform free energy calculations for the elementary steps of the reaction. We investigate the effects of solvent dynamics and in particular the role of quantum mechanical water in the dehydration mechanism. We present results supporting a mechanism that proceeds via water-mediated proton transfers and thus through an enol intermediate. We find that the first dehydration may take place by two, low-energy pathways requiring, respectively, 20.9 and 18.8 kcal/mol of activation free energy. The second dehydration requires 19.9 kcal/mol of activation free energy while for the overall reaction we compute a free energy change of ?8 kcal/mol.

  2. Effect of locked nucleic acid (LNA) modification on hybridization kinetics of DNA duplex.

    PubMed

    Arora, Amit; Kaur, Harleen; Wengel, Jesper; Maiti, Souvik

    2008-01-01

    The effect of locked nucleic acid (LNA) modification on hybridization kinetics of DNA duplex formation has been studied at varying salt concentration (Na(+) and Mg(2+)) using surface-plasmon resonance. The study suggested that the increased stability of LNA containing duplexes mainly originates from the slower dissociation rates constants of the duplexes. An increase in salt concentration increased the binding affinity of the individual duplexes by raising their association rate constants. Monitoring the change in binding affinity with respect to salt concentration revealed that of LNA-associated enhancement in helical stability mainly results from the changes in the non-electrostatic interactions upon duplex formation. PMID:18776431

  3. A unique platinum-graphene hybrid structure for high activity and durability in oxygen reduction reaction

    PubMed Central

    Wang, Chengming; Ma, Liang; Liao, Lingwen; Bai, Song; Long, Ran; Zuo, Ming; Xiong, Yujie

    2013-01-01

    It remains a grand challenge to achieve both high activity and durability in Pt electrocatalysts for oxygen reduction reaction (ORR) in fuel cells. Here we develop a class of Pt highly concave cubic (HCC) nanocrystals, which are enriched with high-index facets, to enable high ORR activity. The durability of HCC nanocrystals can be significantly improved via assembly with graphene. Meanwhile, the unique hybrid structure displays further enhanced specific activity, which is 7-fold greater than the state-of-the-art Pt/C catalysts. Strikingly, it exhibits impressive performance in terms of half-wave potential (E1/2). The E1/2 of 0.967?V at the Pt loading as low as 46??g cm?2, which stands as 63?mV higher than that of the Pt/C catalysts, is slightly superior to the record observed for the most active porous Pt-Ni catalyst in literature. This work paves the way to designing high-performance electrocatalysts by modulating their surface and interface with loading substrates. PMID:23999570

  4. Chemical Reaction of Ultracold Atoms and Ions in a Hybrid Trap

    E-print Network

    Rellergert, Wade G; Kotochigova, Svetlana; Petrov, Alexander; Chen, Kuang; Schowalter, Steven J; Hudson, Eric R

    2011-01-01

    Interactions between cold ions and atoms have been proposed for use in implementing quantum gates\\cite{Idziaszek2007}, probing quantum gases\\cite{Sherkunov2009}, observing novel charge-transport dynamics\\cite{Cote2000}, and sympathetically cooling atomic and molecular systems which cannot be laser cooled\\cite{Smith2005,Hudson2009}. Furthermore, the chemistry between cold ions and atoms is foundational to issues in modern astrophysics, including the formation of stars, planets, and interstellar clouds\\cite{Smith1992}, the diffuse interstellar bands\\cite{Reddy2010}, and the post-recombination epoch of the early universe\\cite{Stancil1996b}. However, as pointed out in refs 9 and 10, both experimental data and a theoretical description of the ion-atom interaction at low temperatures, reached in these modern atomic physics experiments and the interstellar environment, are still largely missing. Here we observe a chemical reaction between ultracold $^{174}$Yb$^+$ ions and $^{40}$Ca atoms held in a hybrid trap. We me...

  5. Structure-Switching Aptamer Triggering Hybridization Chain Reaction on the Cell Surface for Activatable Theranostics.

    PubMed

    Wang, Yu-Min; Wu, Zhan; Liu, Si-Jia; Chu, Xia

    2015-07-01

    The ability to probe low-abundance biomolecules or transport a high-load drug in target cells is essential for biology and theranostics. We develop a novel activatable theranostic approach by using a structure-switching aptamer triggered hybridization chain reaction (HCR) on the cell surface, which for the first time creates an aptamer platform enabling real-time activation and amplification for fluorescence imaging and targeting therapy. The aptamer probe is designed not to initiate HCR in its free state but trigger HCR on binding to the target cell via structure switching. The HCR not only amplifies fluorescence signals from a fluorescence-quenched probe for activatable tumor imaging but also accumulates high-load prodrugs from a drug-labeled probe and induces its uptake and conversion into cisplatin in cells for selective tumor therapy. An in vitro assay shows that this approach affords efficient signal amplification for fluorescence detection of target protein tyrosine kinase-7 (PTK7) with a detection limit of 1 pM. Live cell studies reveal that it provides high-contrast fluorescence imaging and highly sensitive detection of tumor cells, while renders high-efficiency drug delivery into tumor cells via an endocytosis pathway. The results imply the potential of the developed approach as a promising platform for early stage diagnosis and precise therapy of tumors. PMID:26044187

  6. Chlorogenic acid-arabinose hybrid domains in coffee melanoidins: Evidences from a model system.

    PubMed

    Moreira, Ana S P; Coimbra, Manuel A; Nunes, Fernando M; Passos, Cláudia P; Santos, Sónia A O; Silvestre, Armando J D; Silva, André M N; Rangel, Maria; Domingues, M Rosário M

    2015-10-15

    Arabinose from arabinogalactan side chains was hypothesized as a possible binding site for chlorogenic acids in coffee melanoidins. To investigate this hypothesis, a mixture of 5-O-caffeoylquinic acid (5-CQA), the most abundant chlorogenic acid in green coffee beans, and (?1?5)-l-arabinotriose, structurally related to arabinogalactan side chains, was submitted to dry thermal treatments. The compounds formed during thermal processing were identified by electrospray ionization mass spectrometry (ESI-MS) and characterized by tandem MS (ESI-MS(n)). Compounds composed by one or two CQAs covalently linked with pentose (Pent) residues (1-12) were identified, along with compounds bearing a sugar moiety but composed exclusively by the quinic or caffeic acid moiety of CQAs. The presence of isomers was demonstrated by liquid chromatography online coupled to ESI-MS and ESI-MS(n). Pent1-2CQA were identified in coffee samples. These results give evidence for a diversity of chlorogenic acid-arabinose hybrids formed during roasting, opening new perspectives for their identification in melanoidin structures. PMID:25952851

  7. Cross-reactions in patch testing and photopatch testing with ketoprofen, thiaprophenic acid, and cinnamic aldehyde

    Microsoft Academic Search

    Paolo Pigatto; Andrea Bigardi; Agostina Legori; Rossano Valsecchi; Mauro Picardo

    1996-01-01

    In the last 7 years, we have studied 123 patients with allergic reactions to topical arylpropionic anti-inflammatory drugs. We have investigated the rate of sensitization and the irritant potential of one of them, ketoprofen, and its cross-reactivity with such other derivatives as ibuproxam, ibuprofen, naproxen, fenoprofen, flurbiprofen, and thiaprofenic acid. Sensitization was single in most cases, and ketoprofen was the

  8. Control of the Chlorine Dioxide-Iodine-Malonic Acid Oscillating Reaction by Illumination

    E-print Network

    Epstein, Irving R.

    Control of the Chlorine Dioxide-Iodine-Malonic Acid Oscillating Reaction by Illumination Alberto P, Massachusetts 02454-9110 ReceiVed April 1, 1999 Abstract: We show that illumination of the chlorine dioxide-iodine, in which iodine atoms produced by photodissociation of molecular iodine initiate reduction of chlorine

  9. Non-invasive analysis of metabolic reactions in body tissues, the case of myocardial fatty acids

    Microsoft Academic Search

    L. E. Feinendegen; K. Vyska; Chr. Freundlieb; A. Höck; H. J. Machulla; G. Kloster; G. Stöcklin

    1981-01-01

    1.In vivo observations of metabolic reactions require a) the knowledge of the metabolic pathway involved, b) the proper choice of tracer, c) the proper placement of tracer on to the substrate with respect to its anabolic and catabolic portion, d) counting techniques for separately observing the anabolic and catabolic substrate portion, e) proof of applicability of the method.2.Fatty acid catabolism

  10. Chemical modification of carbon fiber surfaces by nitric acid oxidation followed by reaction with tetraethylenepentamine

    Microsoft Academic Search

    C. U. Pittman; G.-R. He; B. Wu; S. D. Gardner

    1997-01-01

    Amino groups react rapidly with both isocyanates and epoxides. Thus, to prepare carbon fibers which might exhibit enhanced adhesion to both polyurethanes and epoxy resin matrices, attempts were made to introduce a high surface amine concentration onto high-strength carbon fibers (derived from PAN) by nitric acid oxidation followed by reaction with excess tetraethylenepentamine (TEPA). Fibers were oxidized with concentrated (70%)

  11. Related base sequences in the DNA of simple and complex organisms. II. The interpretation of DNA\\/RNA hybridization studies with mammalian nucleic acids

    Microsoft Academic Search

    Robert B. Church; Brian J. McCarthy

    1968-01-01

    A comparison has been made of the properties of hybridization reactions using mouse RNA and B. subtilisRNA. By virtue of the high rates of reaction of mammalian RNA and the imperfect nature of the base pairing in the hybrids formed, it is concluded that these reactions are not locus-specific. The same cross-reaction is obtained between polynucleotides representing similar but not

  12. Use of Hybridization Chain Reaction-Fluorescent In Situ Hybridization To Track Gene Expression by Both Partners during Initiation of Symbiosis.

    PubMed

    Nikolakakis, K; Lehnert, E; McFall-Ngai, M J; Ruby, E G

    2015-07-15

    The establishment of a productive symbiosis between Euprymna scolopes, the Hawaiian bobtail squid, and its luminous bacterial symbiont, Vibrio fischeri, is mediated by transcriptional changes in both partners. A key challenge to unraveling the steps required to successfully initiate this and many other symbiotic associations is characterization of the timing and location of these changes. We report on the adaptation of hybridization chain reaction-fluorescent in situ hybridization (HCR-FISH) to simultaneously probe the spatiotemporal regulation of targeted genes in both E. scolopes and V. fischeri. This method revealed localized, transcriptionally coregulated epithelial cells within the light organ that responded directly to the presence of bacterial cells while, at the same time, provided a sensitive means to directly show regulated gene expression within the symbiont population. Thus, HCR-FISH provides a new approach for characterizing habitat transition in bacteria and for discovering host tissue responses to colonization. PMID:25956763

  13. Synthesis of pyrrolidine derivatives by a platinum/brønsted acid relay catalytic cascade reaction.

    PubMed

    Galván, Alicia; Calleja, Jonás; Fañanás, Francisco J; Rodríguez, Félix

    2015-02-16

    A new catalytic reaction for the synthesis of pyrrolidine derivatives is presented. The method implies the coupling of N-Boc-protected alkynamine derivatives and appropriate alkenes or alkynes in a process catalysed by a platinum/triflic acid catalytic binary system. This reaction is believed to proceed through a cascade process implying an initial platinum-catalysed cycloisomerization of the alkynamine derivative followed by a triflic acid promoted nucleophilic addition of the alkene or alkyne and trapping of the cationic species formed by the Boc group. Not only simple alkenes and alkynes were used in this reaction but also allyltrimethylsilane and propargyltrimethylsilane. Particularly, when allyltrimethylsilane is used as the alkene counterpart interesting bicyclic compounds containing a trimethylsilane group are obtained. However, when propargyltrimethylsilane is used in the presence of water we observed the formation of a related bicyclic compound lacking the trimethylsilane group and containing an exocyclic carbon-carbon bond. PMID:25557076

  14. Chemoselective Boron-Catalyzed Nucleophilic Activation of Carboxylic Acids for Mannich-Type Reactions.

    PubMed

    Morita, Yuya; Yamamoto, Tomohiro; Nagai, Hideoki; Shimizu, Yohei; Kanai, Motomu

    2015-06-10

    The carboxyl group (COOH) is an omnipresent functional group in organic molecules, and its direct catalytic activation represents an attractive synthetic method. Herein, we describe the first example of a direct catalytic nucleophilic activation of carboxylic acids with BH3·SMe2, after which the acids are able to act as carbon nucleophiles, i.e. enolates, in Mannich-type reactions. This reaction proceeds with a mild organic base (DBU) and exhibits high levels of functional group tolerance. The boron catalyst is highly chemoselective toward the COOH group, even in the presence of other carbonyl moieties, such as amides, esters, or ketones. Furthermore, this catalytic method can be extended to highly enantioselective Mannich-type reactions by using a (R)-3,3'-I2-BINOL-substituted boron catalyst. PMID:26011419

  15. Tris(pentafluorophenyl)borane: a special boron Lewis acid for special reactions.

    PubMed

    Erker, Gerhard

    2005-06-01

    Tris(pentafluorophenyl)borane is best known for its role as an excellent activator component in homogeneous Ziegler-Natta chemistry. However, the special properties of B(C6F5)3 have made this strong boron Lewis acid an increasingly used catalyst or stoichiometric reagent in organic and organometallic chemistry. This includes catalytic hydrometallation reactions, alkylations and catalyzed aldol-type reactions. B(C6F5)3 catalyzes tautomerizations and can sometimes stabilize less favoured tautomeric forms by adduct formation. It induces some rather unusual reactions of early metal acetylide complexes and can help in stabilizing uncommon coordination geometries of carbon. The growing number of such examples indicates an increasing application potential of the useful Lewis acid B(C6F5)3 aside from its established role in olefin polymerization catalysis. PMID:15909033

  16. Thermodynamic dependence of DNA\\/DNA and DNA\\/RNA hybridization reactions on temperature and ionic strength

    Microsoft Academic Search

    Brian E. Lang; Frederick P. Schwarz

    2007-01-01

    The thermodynamics of 5?-ATGCTGATGC-3? binding to its complementary DNA and RNA strands was determined in sodium phosphate buffer under varying conditions of temperature and salt concentration from isothermal titration calorimetry (ITC). The Gibbs free energy change, ?G° of the DNA hybridization reactions increased by about 6 kJ mol?1 from 20 °C to 37 °C and exhibited heat capacity changes of ?1.42±0.09 kJ mol?1 K?1

  17. Analysis of Epstein-Barr viral genomes in lymphoid malignancy using southern blotting, polymerase chain reaction and in situ hybridization

    Microsoft Academic Search

    Kohichi Ohshima; Masahiro Kikuchi; Fuyuki Eguchi; Yuhichi Masuda; Yoshiaki Sumiyoshi; Hidehito Mohtai; Morishige Takeshita; Nobuhiro Kimura

    1990-01-01

    Summary  109 malignant lymphomas were surveyed by Southern blot analysis and polymerase chain reaction (PCR) for Epstein-Barr virus\\u000a (EBV) DNA and compared with 16 examples of non-neoplastic lymphadenopathy and 4 normal thymuses. In specimens positive by\\u000a the method of Southern and PCR, in situ hybridization studies were performed on formalin-fixed, paraffin-embedded sections.\\u000a By Southern blot analysis, two of seven Hodgkin’s disease

  18. Sol–gel derived poly(vinyl alcohol)\\/maleic acid\\/silica hybrid membrane for desalination by pervaporation

    Microsoft Academic Search

    Zongli Xie; Manh Hoang; Tuan Duong; Derrick Ng; Buu Dao; Stephen Gray

    2011-01-01

    Highly dispersed homogeneous hybrid polymer–inorganic membranes based on poly(vinyl alcohol) (PVA), maleic acid (MA) and inorganic silica were synthesized via a sol–gel method. Tetraethoxy-silane (TEOS) was used as the silica precursor with MA as an additional crosslinking agent. A range of techniques such as FTIR, SEM, TGA, XRD and DSC were used to characterise the nanostructure and properties of hybrid

  19. Fatty alcohols or fatty acids as niosomal hybrid carrier: Effect on vesicle size, encapsulation efficiency and in vitro dye release

    Microsoft Academic Search

    Prasun Bandyopadhyay; Madrid Johnson

    2007-01-01

    Niosomal hybrid mixtures are prepared with bilayer stabilizer cholesterol from non-ionic surfactants span 20 (HLB value 8.6), span 60 (HLB 4.7) and span 85 (HLB 1.8) in presence of dicetyl phosphate (DCP) where fatty acids or fatty alcohols (C14, C16 and C18) are used as carrier. Hybrid mixtures upon hydration with aqueous phosphate buffer (pH 7.4) spontaneously produce vesicular phase

  20. Detection of Dehalococcoides spp. by peptide nucleic acid fluorescent in situ hybridization.

    PubMed

    Danko, Anthony S; Fontenete, Silvia J; de Aquino Leite, Daniel; Leitão, Patrícia O; Almeida, Carina; Schaefer, Charles E; Vainberg, Simon; Steffan, Robert J; Azevedo, Nuno F

    2014-01-01

    Chlorinated solvents including tetrachloroethene (perchloroethene and trichloroethene), are widely used industrial solvents. Improper use and disposal of these chemicals has led to a widespread contamination. Anaerobic treatment technologies that utilize Dehalococcoides spp. can be an effective tool to remediate these contaminated sites. Therefore, the aim of this study was to develop, optimize and validate peptide nucleic acid (PNA) probes for the detection of Dehalococcoides spp. in both pure and mixed cultures. PNA probes were designed by adapting previously published DNA probes targeting the region of the point mutations described for discriminating between the Dehalococcoides spp. strain CBDB1 and strain 195 lineages. Different fixation, hybridization and washing procedures were tested. The results indicated that the PNA probes hybridized specifically and with a high sensitivity to their corresponding lineages, and that the PNA probes developed during this work can be used in a duplex assay to distinguish between strain CBDB1 and strain 195 lineages, even in complex mixed cultures. This work demonstrates the effectiveness of using PNA fluorescence in situ hybridization to distinguish between two metabolically and genetically distinct Dehalococcoides strains, and they can have strong implications in the monitoring and differentiation of Dehalococcoides populations in laboratory cultures and at contaminated sites. PMID:24970105

  1. A hybrid pore-scale and continuum-scale model for solute diffusion, reaction, and biofilm development in porous media

    NASA Astrophysics Data System (ADS)

    Tang, Youneng; Valocchi, Albert J.; Werth, Charles J.

    2015-03-01

    It is a challenge to upscale solute transport in porous media for multispecies bio-kinetic reactions because of incomplete mixing within the elementary volume and because biofilm growth can change porosity and affect pore-scale flow and diffusion. To address this challenge, we present a hybrid model that couples pore-scale subdomains to continuum-scale subdomains. While the pore-scale subdomains involving significant biofilm growth and reaction are simulated using pore-scale equations, the other subdomains are simulated using continuum-scale equations to save computational time. The pore-scale and continuum-scale subdomains are coupled using a mortar method to ensure continuity of solute concentration and flux at the interfaces. We present results for a simplified two-dimensional system, neglect advection, and use dual Monod kinetics for solute utilization and biofilm growth. The results based on the hybrid model are consistent with the results based on a pore-scale model for three test cases that cover a wide range of Damköhler (Da = reaction rate/diffusion rate) numbers for both homogeneous (spatially periodic) and heterogeneous pore structures. We compare results from the hybrid method with an upscaled continuum model and show that the latter is valid only for cases of small Damköhler numbers, consistent with other results reported in the literature.

  2. Development of rapeseed with high erucic acid content by asymmetric somatic hybridization between Brassica napus and Crambe abyssinica.

    PubMed

    Wang, Y P; Sonntag, K; Rudloff, E

    2003-05-01

    PEG-induced asymmetric somatic hybridization between Brassica napus and Crambe abyssinica was carried out. C. abyssinica is an annual cruciferous oil crop with a high content of erucic acid in the seed oil valuable for technical purposes. UV-irradiated mesophyll protoplasts of C. abyssinica cv 'Carmen' and cv 'Galactica' were fused with hypocotyl protoplasts of different genotypes of B. napus cv 'Maplus' and breeding line '11502'. Shoot regeneration frequency varied between 6.1% and 20.8% among the different doses of UV-irradiation, ranging from 0.05 J/cm(2) to 0.30 J/cm(2). In total, 124 shoots were regenerated, of which 20 asymmetric somatic hybrids were obtained and verified by nuclear DNA content and AFLP analysis. AFLP data showed that some of the characteristic bands from C. abyssinica were present in the hybrids. Cytological analysis of these hybrids showed that 9 out of 20 asymmetric hybrids had 38 chromosomes, the others contained 40-78 chromosomes, having additional chromosomes between 2 and 40 beyond the 38 expected for B. napus. The investigation into the fertility of asymmetric somatic hybrids indicated that the fertility increased with increasing UV-doses ranging from 0.05 J/cm(2) to 0.15 J/cm(2). All of the hybrids were cultured to full maturity, and could be fertilized and set seeds after self-pollination or backcrosses with B. napus. An analysis of fatty acid composition in the seeds was conducted and found to contain significantly greater amounts of erucic acid than B. napus. This study indicates that UV-irradiation could be used as a tool to produce asymmetric somatic hybrids and to promote the fertility of the hybrids. PMID:12687349

  3. Effect of channel length on the electrical response of carbon nanotube field-effect transistors to deoxyribonucleic acid hybridization.

    PubMed

    Salila Vijayalal Mohan, Hari Krishna; An, Jianing; Zhang, Yani; Wong, Chee How; Zheng, Lianxi

    2014-01-01

    A single-walled carbon nanotube (SWCNT) in a field-effect transistor (FET) configuration provides an ideal electronic path for label-free detection of nucleic acid hybridization. The simultaneous influence of more than one response mechanism in hybridization detection causes a variation in electrical parameters such as conductance, transconductance, threshold voltage and hysteresis gap. The channel length (L) dependence of each of these parameters necessitates the need to include them when interpreting the effect of L on the response to hybridization. Using the definitions of intrinsic effective mobility (µe) and device field-effect mobility (µf), two new parameters were defined to interpret the effect of L on the FET response to hybridization. Our results indicate that FETs with ?300 µm long SWCNT exhibited the most appreciable response to hybridization, which complied with the variation trend in response to the newly defined parameters. PMID:25551036

  4. Reaction of dopa decarboxylase with L-aromatic amino acids under aerobic and anaerobic conditions.

    PubMed Central

    Bertoldi, M; Borri Voltattorni, C

    2000-01-01

    Analysis of the reaction of dopa decarboxylase (DDC) with L-dopa reveals that loss of decarboxylase activity with time is observed at enzyme concentrations approximately equal to the binding constant, K(d), of the enzyme for pyridoxal 5'-phosphate (PLP). Instead, at enzyme concentrations higher than K(d) the course of product formation proceeds linearly until complete consumption of the substrate. Evidence is provided that under both experimental conditions no pyridoxamine 5'-phosphate (PMP) is formed during the reaction and that dissociation of coenzyme occurs at low enzyme concentration, leading to the formation of a PLP-L-dopa Pictet-Spengler cyclic adduct. Taken together, these results indicate that decarboxylation-dependent transamination does not accompany the decarboxylation of L-dopa proposed previously [O'Leary and Baughn (1977) J. Biol. Chem. 252, 7168-7173]. Nevertheless, when the reaction of DDC with L-dopa is studied under anaerobic conditions at an enzyme concentration higher than K(d), we observe that (1) the enzyme is gradually inactivated and inactivation is associated with PMP formation and (2) the initial velocity of decarboxylation is approximately half of that in the presence of O(2). Similar behaviour is observed by comparing the reaction with L-5-hydroxytryptophan occurring in aerobiosis or in anaerobiosis. Therefore the reaction of DDC with L-aromatic amino acids seems to be under O(2) control. In contrast, the reactivity of the enzyme with L-aromatic amino acids does not change in the presence or absence of O(2). These and other results, together with previous results on the effect exerted by O(2) on reaction specificity of DDC towards aromatic amines [Bertoldi, Frigeri, Paci and Borri Voltattorni (1999) J. Biol. Chem. 274, 5514-5521], suggest a productive effect of O(2) on an intermediate complex of the reaction of the enzyme with L-aromatic amino acids or aromatic amines. PMID:11085948

  5. Acid-catalyzed transformation of ionophore veterinary antibiotics: reaction mechanism and product implications.

    PubMed

    Sun, Peizhe; Yao, Hong; Minakata, Daisuke; Crittenden, John C; Pavlostathis, Spyros G; Huang, Ching-Hua

    2013-07-01

    Ionophore antibiotics (IPAs) are polyether antimicrobials widely used in the livestock industry and may enter the environment via land application of animal waste and agricultural runoff. Information is scarce regarding potential transformation of IPAs under environmental conditions. This study is among the first to identify the propensity of IPAs to undergo acid-catalyzed transformation in mildly acidic aquatic systems and characterize the reactions in depth. The study focused on the most widely used monensin (MON) and salinomycin (SAL), and also included narasin (NAR) in the investigation. All three IPAs are susceptible to acid-catalyzed transformation. MON reacts much more slowly than SAL and NAR and exhibits a different kinetic behavior that is further evaluated by a reversible reaction kinetic model. Extensive product characterization identifies that the spiro-ketal group of IPAs is the reactive site for the acid-catalyzed hydrolytic transformation, yielding predominantly isomeric and other products. Toxicity evaluation of the transformation products shows that the products retain some antimicrobial properties. The occurrence of IPAs and isomeric transformation products is also observed in poultry litter and agricultural runoff samples. Considering the common presence of mildly acidic environments (pH 4-7) in soils and waters, the acid-catalyzed transformation identified in this study likely plays an important role in the environmental fate of IPAs. PMID:23373828

  6. SNBRFinder: A Sequence-Based Hybrid Algorithm for Enhanced Prediction of Nucleic Acid-Binding Residues

    PubMed Central

    Sun, Jun; Liu, Rong

    2015-01-01

    Protein-nucleic acid interactions are central to various fundamental biological processes. Automated methods capable of reliably identifying DNA- and RNA-binding residues in protein sequence are assuming ever-increasing importance. The majority of current algorithms rely on feature-based prediction, but their accuracy remains to be further improved. Here we propose a sequence-based hybrid algorithm SNBRFinder (Sequence-based Nucleic acid-Binding Residue Finder) by merging a feature predictor SNBRFinderF and a template predictor SNBRFinderT. SNBRFinderF was established using the support vector machine whose inputs include sequence profile and other complementary sequence descriptors, while SNBRFinderT was implemented with the sequence alignment algorithm based on profile hidden Markov models to capture the weakly homologous template of query sequence. Experimental results show that SNBRFinderF was clearly superior to the commonly used sequence profile-based predictor and SNBRFinderT can achieve comparable performance to the structure-based template methods. Leveraging the complementary relationship between these two predictors, SNBRFinder reasonably improved the performance of both DNA- and RNA-binding residue predictions. More importantly, the sequence-based hybrid prediction reached competitive performance relative to our previous structure-based counterpart. Our extensive and stringent comparisons show that SNBRFinder has obvious advantages over the existing sequence-based prediction algorithms. The value of our algorithm is highlighted by establishing an easy-to-use web server that is freely accessible at http://ibi.hzau.edu.cn/SNBRFinder. PMID:26176857

  7. Kinetics of the reaction between Pu(III) and Fe(III) in nitric acid solution

    SciTech Connect

    Koltunov, V.S.; Zhuravleva, G.I.

    1988-01-01

    The kinetics of the reaction between Pu/sup (III)/ and Fe/sup (III)/ in an aqueous nitric acid solution in the presence of persulfate ions at a constant ionic strength of the solution was studied spectrophotometrically. It was shown that the reaction is first order with respect to the reagents; its rate is practically independent of the concentration of the H/sup +/ and S/sub 2/O/sub 8//sup 2 -/ ions and with increase in the analytical HNO/sub 3/ concentration at variable ionic strength, it first increases, and then decreases. The temperature dependence of the reaction was determined, and its thermodynamic activation parameters were calculated. A possible mechanism for the reaction between Pu/sup (III)/ and Fe/sup (III)/ was proposed.

  8. Feasibility Study of Two Candidate Reaction Wheel/thruster Hybrid Control Architecture Designs for the Cassini Spacecraft

    NASA Technical Reports Server (NTRS)

    Macala, Glenn A.; Lee, Allan Y.; Wang, Eric K.

    2012-01-01

    As the first spacecraft to achieve orbit at Saturn in 2004, Cassini has collected science data throughout its four-year prime mission (2004-08), and has since been approved for a first and second extended mission through 2017. Cassini carries a set of three "fixed" reaction wheels and a backup reaction wheel (reaction wheel #4) is mounted on top of an articulable platform. If necessary, this platform could be articulated to orient the backup reaction wheel with the degraded wheel. The reaction wheels are used primarily for attitude control when precise and stable pointing of a science instrument such as the narrow angle camera is required. In 2001-02, reaction wheel #3 exhibited signs of bearing cage instability. As a result, reaction wheel #4 was articulated to align with reaction wheel #3. Beginning in July 2003, Cassini was controlled using wheel #1, #2, and #4. From their first use in the spring of 2000 until today, reaction wheels #1 and #2 have accumulated more than3.5 billions revolutions each. As such, in spite of very carefully management of the wheel spin rates by the mission operation team, there are some observed increases in the drag torque of the wheels' bearings. Hence, the mission operations team must prepare for the contingency scenario in which the reaction wheel #1 (in addition to wheel #3) had degraded. In this hypothetical fault scenario, the two remaining reaction wheels (#2 and #4) will not be able to provide precise and stable three-axis control of the spacecraft. In this study, we evaluate the feasibility of controlling Cassini using the two remaining reaction wheels and four thrusters to meet the science pointing requirements for two key science operational modes: the Optical Remote Sensing and Downlink, Fields, Particles, & Waves operation modes. The performance (e.g., pointing control error, pointing stability, hydrazine consumption rate, etc.) of the hybrid controllers in both operations scenarios will be compared with those achieved using an all-thruster controller design. Strength and weaknesses of the hybrid control architecture are assessed quantitatively.

  9. Mechanism and kinetics of the water-assisted formic acid + OH reaction under tropospheric conditions.

    PubMed

    Iuga, Cristina; Alvarez-Idaboy, J Raul; Vivier-Bunge, Annik

    2011-05-26

    In this work, we have revisited the mechanism of the formic acid + OH radical reaction assisted by a single water molecule. Density functional methods are employed in conjunction with large basis sets to explore the potential energy surface of this radical-molecule reaction. Computational kinetics calculations in a pseudo-second-order mechanism have been performed, taking into account average atmospheric water concentrations and temperatures. We have used this method recently to study the single water molecule assisted H-abstraction by OH radicals (Iuga, C.; Alvarez-Idaboy, J. R.; Reyes, L.; Vivier-Bunge, A. J. Phys. Chem. Lett. 2010, 1, 3112; Iuga, C.; Alvarez-Idaboy, J. R.; Vivier-Bunge, A. Chem. Phys. Lett. 2010, 501, 11; Iuga, C.; Alvarez-Idaboy, J. R.; Vivier-Bunge, A. Theor. Chem. Acc. 2011, 129, 209), and we showed that the initial water complexation step is essential in the rate constant calculation. In the formic acid reaction with OH radicals, we find that the water-acid complex concentration is small but relevant under atmospheric conditions, and it could in principle be large enough to produce a measurable increase in the overall rate constant. However, the water-assisted process occurs according to a formyl hydrogen abstraction, rather than abstraction of carboxylic hydrogen as in the water-free case. As a result, the overall reaction rate constant is considerably smaller. Products are different in the water-free and water-assisted processes. PMID:21528871

  10. Ozone Sensitivity in Hybrid Poplar Correlates with Insensitivity to Both Salicylic Acid and Jasmonic Acid. The Role of Programmed Cell Death in Lesion Formation1

    Microsoft Academic Search

    Jennifer Riehl Koch; Robert A. Creelman; Steven M. Eshita; Mirjana Seskar; John E. Mullet; Keith R. Davis

    2000-01-01

    Our earlier studies demonstrated that the ozone-sensitive hybrid poplar clone NE-388 displays an attenuated level of ozone-, wound-, and phytopathogen-induced defense gene expression. To determine if this reduced gene activation involves signal transduction pathways dependent on salicylic acid (SA) and\\/or jasmonic acid (JA), we compared the responses of NE-388 and an ozone-tolerant clone, NE-245, to these signal molecules. JA levels

  11. Relative Reaction Rates of Sulfamic Acid and Hydroxylamine with Nitric Acid

    SciTech Connect

    Karraker, D.G.

    2001-03-28

    This report describes a study of comparative reaction rates where the reductant is in excess, as in the 1B bank in the Purex process. The results of this work apply to planned plant tests to partially substitute HAN for the ferrous sulfamate reductant in the Purex 1B bank.

  12. Reactions of clofibric acid with oxidative and reductive radicals-Products, mechanisms, efficiency and toxic effects

    NASA Astrophysics Data System (ADS)

    Csay, Tamás; Rácz, Gergely; Salik, Ádám; Takács, Erzsébet; Wojnárovits, László

    2014-09-01

    The degradation of clofibric acid induced by hydroxyl radical, hydrated electron and O2-•/HO2• reactive species was studied in aqueous solutions. Clofibric acid was decomposed more effectively by hydroxyl radical than by hydrated electron or O2-•/HO2•. Various hydroxylated, dechlorinated and fragmentation products have been identified and quantified. A new LC-MS method was developed based on 18O isotope labeling to follow the formation of hydroxylated derivatives of clofibric acid. Possible degradation pathways have been proposed. The overall degradation was monitored by determination of sum parameters like COD, TOC and AOX. It was found that the organic chlorine degrades very effectively prior to complete mineralization. After the treatment no toxic effect was found according to Vibrio fischeri tests. However, at early stages some of the reaction products were more harmful than clofibric acid.

  13. Reactions of aqueous glucose solution over solid-acid Y-zeolite catalyst at 110-160 C

    SciTech Connect

    Lourvanij, K.; Rorrer, G.L. (Oregon State Univ., Corvallis (United States))

    1993-01-01

    Reactions of glucose with solid-acid Y-zeolite catalyst were studied to see if this heterogeneous system could produce oxygenated hydrocarbons by shape-selective, acid-catalyzed processes at fairly low temperatures. Experimentally, aqueous solutions of glucose (12 wt %) were reacted with HY-zeolite powder in a well-mixed batch reactor at temperatures ranging from 110 to 160 C and catalyst concentrations ranging from 2 to 20 g/150 ml. Unreacted glucose and oxygenated hydrocarbon products were measured by HPLC as a function of reaction time (0-24 h) and process conditions. Glucose conversions of 100% were obtained at 160 C after an 8-h reaction time. The apparent activation energy based on glucose conversion was 23.25 [plus minus] 0.40 kcal/mol. Several acid-catalyzed reactions were identified, including isomerization of glucose to fructose, partial dehydration of glucose to 5-(hydroxymethyl)furfural (HMF), rehydration and cleavage of HMF to formic acid and 4-oxo-pentanoic acid, and carbonization . Polymers of HMF and seven minor additional products in the lower molecular weight organic acids/aldehydes/ketones elution range were also isolated by HPLC. High yields of organic acids relative to HMF and lowered selectivity of HMF in the bulk phase relative to the homogeneous acid-catalyzed reaction suggests the possibility of molecular sieving reactions within the Y-zeolite in addition to reactions on the outer surface of the Y-zeolite particle.

  14. The reaction of iodobenzene-p-sulphonyl chloride (pipsyl chloride) with certain amino acids and peptides, and with insulin

    PubMed Central

    Fletcher, J. C.

    1967-01-01

    1. A system of separation using buffered Celite columns is described that enables the pipsyl derivatives of most of the common amino acids to be separated. 2. The reaction of pipsyl chloride with several amino acids not included in previous studies has been investigated. In particular, knowledge of the acid-soluble pipsyl derivatives of arginine, histidine, lysine, tyrosine and cysteic acid has been extended. 3. Reproducible factors have been obtained that enable corrections to be applied for the breakdown of pipsylamino acids on acid hydrolysis. 4. The reaction of pipsyl chloride with peptides has been studied under various conditions. 5. The extent of the reaction between pipsyl chloride and insulin depends on the nature of the solvent–buffer system, and under the best conditions so far found is about 75% complete. 6. In an Appendix, the separation of pipsylamino acids by thin-layer chromatography is described. PMID:16742498

  15. 40 CFR 721.10429 - Fatty acids, C18-unsatd., dimers, reaction products with 1-piperazineethanamine and tall-oil...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 2013-07-01 false Fatty acids, C18-unsatd., dimers, reaction products...1-piperazineethanamine and tall-oil fatty acids. 721.10429 Section 721.10429...Chemical Substances § 721.10429 Fatty acids, C18 -unsatd., dimers,...

  16. 40 CFR 721.10429 - Fatty acids, C18-unsatd., dimers, reaction products with 1-piperazineethanamine and tall-oil...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 2014-07-01 false Fatty acids, C18-unsatd., dimers, reaction products...1-piperazineethanamine and tall-oil fatty acids. 721.10429 Section 721.10429...Chemical Substances § 721.10429 Fatty acids, C18 -unsatd., dimers,...

  17. Chemically activated formation of organic acids in reactions of the Criegee intermediate with aldehydes and ketones.

    PubMed

    Jalan, Amrit; Allen, Joshua W; Green, William H

    2013-10-21

    Reactions of the Criegee intermediate (CI, ?CH2OO?) are important in atmospheric ozonolysis models. In this work, we compute the rates for reactions between ?CH2OO? and HCHO, CH3CHO and CH3COCH3 leading to the formation of secondary ozonides (SOZ) and organic acids. Relative to infinitely separated reactants, the SOZ in all three cases is found to be 48-51 kcal mol(-1) lower in energy, formed via 1,3-cycloaddition of ?CH2OO? across the C=O bond. The lowest energy pathway found for SOZ decomposition is intramolecular disproportionation of the singlet biradical intermediate formed from cleavage of the O-O bond to form hydroxyalkyl esters. These hydroxyalkyl esters undergo concerted decomposition providing a low energy pathway from SOZ to acids. Geometries and frequencies of all stationary points were obtained using the B3LYP/MG3S DFT model chemistry, and energies were refined using RCCSD(T)-F12a/cc-pVTZ-F12 single-point calculations. RRKM calculations were used to obtain microcanonical rate coefficients (k(E)) and the reservoir state method was used to obtain temperature and pressure dependent rate coefficients (k(T, P)) and product branching ratios. At atmospheric pressure, the yield of collisionally stabilized SOZ was found to increase in the order HCHO < CH3CHO < CH3COCH3 (the highest yield being 10(-4) times lower than the initial ?CH2OO? concentration). At low pressures, chemically activated formation of organic acids (formic acid in the case of HCHO and CH3COCH3, formic and acetic acid in the case of CH3CHO) was found to be the major product channel in agreement with recent direct measurements. Collisional energy transfer parameters and the barrier heights for SOZ reactions were found to be the most sensitive parameters determining SOZ and organic acid yield. PMID:23958859

  18. Reactions templated by nucleic acids: more ways to translate oligonucleotide-based instructions into emerging function.

    PubMed

    Gorska, Katarzyna; Winssinger, Nicolas

    2013-07-01

    The programmability of oligonucleotide recognition offers an attractive platform to direct the assembly of reactive partners that can engage in chemical reactions. Recently, significant progress has been made in both the breadth of chemical transformations and in the functional output of the reaction. Herein we summarize these recent progresses and illustrate their applications to translate oligonucleotide instructions into functional materials and novel architectures (conductive polymers, nanopatterns, novel oligonucleotide junctions); into fluorescent or bioactive molecule using cellular RNA; to interrogate secondary structures or oligonucelic acids; or a synthetic oligomer. PMID:23794204

  19. Heterogeneous reactions on nitric acid trihydrate. [on surfaces of polar stratospheric cloud particles

    NASA Technical Reports Server (NTRS)

    Moore, S. B.; Keyser, L. F.; Leu, M.-T.; Smith, R. H.; Turco, R. P.

    1990-01-01

    The first direct measurements are reported of the reaction probabilities at stratospheric temperatures for two important heterogeneous reactions on nitric acid trihydrate (NAT), the compound which makes up the predominant, type I form of polar stratospheric cloud (PSC). Sticking coefficients and solubilities of HCl and NAT, which are important in modeling physicochemical processes in the stratosphere, are also reported. The results show that the conversion of the chlorine reservoir species in the stratosphere to photochemically active forms can occur within a few days of the first appearance of type I PSCs during the polar winter.

  20. Improved constrained optimization method for reaction-path determination in the generalized hybrid orbital quantum mechanical/molecular mechanical calculations

    NASA Astrophysics Data System (ADS)

    Jung, Jaewoon; Re, Suyong; Sugita, Yuji; Ten-no, Seiichiro

    2013-01-01

    The nudged elastic band (NEB) and string methods are widely used to obtain the reaction path of chemical reactions and phase transitions. In these methods, however, it is difficult to define an accurate Lagrangian to generate the conservative forces. On the other hand, the constrained optimization with locally updated planes (CO-LUP) scheme defines target function properly and suitable for micro-iteration optimizations in quantum mechanical/molecular mechanical (QM/MM) systems, which uses the efficient second order QM optimization. However, the method does have problems of inaccurate estimation of reactions and inappropriate accumulation of images around the energy minimum. We introduce three modifications into the CO-LUP scheme to overcome these problems: (1) An improved tangent estimation of the reaction path, which is used in the NEB method, (2) redistribution of images using an energy-weighted interpolation before updating local tangents, and (3) reduction of the number of constraints, in particular translation/rotation constraints, for improved convergence. First, we test the method on the isomerization of alanine dipeptide without QM/MM calculation, showing that the method is comparable to the string method both in accuracy and efficiency. Next, we apply the method for defining the reaction paths of the rearrangement reaction catalyzed by chorismate mutase (CM) and of the phosphoryl transfer reaction catalyzed by cAMP-dependent protein kinase (PKA) using generalized hybrid orbital QM/MM calculations. The reaction energy barrier of CM is in high agreement with the experimental value. The path of PKA reveals that the enzyme reaction is associative and there is a late transfer of the substrate proton to Asp 166, which is in agreement with the recently published result using the NEB method.

  1. Ruthenium(III) catalysis in the reaction of hexacyanoferrate(III) and iodide ions in perchloric acid medium

    Microsoft Academic Search

    Praveen K. Tandon; Alka Mehrotra; Manish Srivastava; Mamta Dhusia; Santosh B. Singh

    2007-01-01

    RuCl3 can further catalyze the reaction between hexacyanoferrate(III) and iodide ions, which is already catalyzed by the hydrogen\\u000a ions obtained from perchloric acid. Rate, when the reaction is catalyzed only by the hydrogen ions, was separated graphically\\u000a from the rate when ruthenium(III) and H+ ions both catalyze the reaction. Reactions studied separately in the presence as well as in the

  2. Development and operation of a hybrid acid-alkaline advanced water electrolysis cell

    NASA Astrophysics Data System (ADS)

    Teschke, O.; Zwanziger, M.

    A hybrid acid-alkaline water electrolysis cell has been developed for hydrogen production. The cell is based on the use of an acidic solution at the cathode and a basic solution at the anode to reduce the minimum theoretical voltage for water decomposition from the thermoneutral potential of 1.47 V to close to 1.4 V at 25 C and 1 atm. The pH differential is maintained by the removal of OH ions from the cathode section and water removal from the anode section, which can be driven by heat energy. A practical cell has been built using a solid polymer electrolyte in which, however, the cathodic compartment is not acidic but neutral. Tests with a platinum black cathode catalyst and a platinum-iridium anode catalyst have resulted in steady-state water hydrolysis at an applied voltage of 0.9 V, and a V-I diagram with a considerably lower slope than that of a conventional cell has been obtained at 90 C.

  3. Reactions of acids with naphthyridine-functionalized ferrocenes: protonation and metal extrusion.

    PubMed

    Sadhukhan, Nabanita; Sarkar, Mithun; Ghatak, Tapas; Rahaman, S M Wahidur; Barbour, Leonard J; Bera, Jitendra K

    2013-02-01

    Reaction of 1,8-naphthyrid-2-yl-ferrocene (FcNP) with a variety of acids affords protonated salts at first, whereas longer reaction time leads to partial demetalation of FcNP resulting in a series of Fe complexes. The corresponding salts [FcNP·H][X] (X = BF(4) or CF(3)SO(3) (1)) are isolated for HBF(4) and CF(3)SO(3)H. Reaction of FcNP with equimolar amount of CF(3)CO(2)H for 12 h affords a neutral complex [Fe(FcNP)(2)(O(2)CCF(3))(2)(OH(2))(2)] (2). Use of excess acid gave a trinuclear Fe(II) complex [Fe(3)(H(2)O)(2)(O(2)CCF(3))(8)(FcNP·H)(2)] (3). Three linear iron atoms are held together by four bridging trifluoroacetates and two aqua ligands in a symmetric fashion. Reaction with ethereal solution of HCl afforded [(FcNP·H)(3)(Cl)][FeCl(4)](2) (4) irrespective of the amount of the acid used. Even the picric acid (HPic) led to metal extrusion giving rise to [Fe(2)(Cl)(2)(FcNP)(2)(Pic)(2)] (5) when crystallized from dichloromethane. Metal extrusion was also observed for CF(3)SO(3)H, but an analytically pure compound could not be isolated. The demetalation reaction proceeds with an initial proton attack to the distal nitrogen of the NP unit. Subsequently, coordination of the conjugate base to the electrophilic Fe facilitates the release of Cp rings from metal. The conjugate base plays an important role in the demetalation process and favors the isolation of the Fe complex as well. The 1,1'-bis(1,8-naphthyrid-2-yl)ferrocene (FcNP(2)) does not undergo demetalation under identical conditions. Two NP units share one positive charge causing the Fe-Cp bonds weakened to an extent that is not sufficient for demetalation. X-ray structure of the monoprotonated FcNP(2) reveals a discrete dimer [(FcNP(2)·H)](2)[OTf](2) (6) supported by two N-H···N hydrogen bonds. Crystal packing and dispersive forces associated with intra- and intermolecular ?-? stacking interactions (NP···NP and Cp···NP) allow the formation of the dimer in the solid-state. The protonation and demetalation reactions of FcNP and FcNP(2) with a variety of acids are reported. PMID:23347083

  4. Aptamer-based organic-silica hybrid affinity monolith prepared via "thiol-ene" click reaction for extraction of thrombin.

    PubMed

    Wang, Zheng; Zhao, Jin-Cheng; Lian, Hong-Zhen; Chen, Hong-Yuan

    2015-06-01

    A novel strategy for preparing aptamer-based organic-silica hybrid monolithic column was developed via "thiol-ene" click chemistry. Due to the large specific surface area of the hybrid matrix and the simplicity, rapidness and high efficiency of "thiol-ene" click reaction, the average coverage density of aptamer on the organic-silica hybrid monolith reached 420pmol?L(-1). Human ?-thrombin can be captured on the prepared affinity monolithic column with high specificity and eluted by NaClO4 solution. N-p-tosyl-Gly-Pro-Arg p-nitroanilide acetate was used as the sensitive chromogenic substrate of thrombin. The thrombin enriched by this affinity column was detected with a detection of limit of 0.01?M by spectrophotometry. Furthermore, the extraction recovery of thrombin at 0.15?M in human serum was 91.8% with a relative standard deviation of 4.0%. These results indicated that "thiol-ene" click chemistry provided a promising technique to immobilize aptamer on organic-inorganic hybrid monolith and the easily-assembled affinity monolithic material could be used to realize highly selective recognition of trace proteins. PMID:25863371

  5. Effects of ascorbic acid on sperm motility, viability, acrosome reaction and DNA integrity in teratozoospermic samples

    PubMed Central

    Fanaei, Hamed; Khayat, Samira; Halvaei, Iman; Ramezani, Vahid; Azizi, Yaser; Kasaeian, Amir; Mardaneh, Jalal; Parvizi, Mohammad Reza; Akrami, Maryam

    2014-01-01

    Background: Oxidative stress in teratozoospermic semen samples caused poor assisted reproductive techniques (ART) outcomes. Among antioxidants, ascorbic acid is a naturally occurring free radical scavenger and as such its presence assists various other mechanisms in decreasing numerous disruptive free radical processes. Objective: The main goal of this study was to evaluate potential protective effects of ascorbic acid supplementation during in vitro culture of teratozoospermic specimens. Materials and Methods: Teratozoospermic semen samples that collected from 15 volunteers were processed, centrifuged and incubated at 37oC until sperm swimmed-up. Supernatant was divided into four groups and incubated at 37oC for one hour under different experimental conditions: Control, 10 µm A23187, 600µm ascorbic acid and 10 µm A23187+600 µm ascorbic acid. After incubation sperm motility, viability, acrosome reaction, DNA damage and malondialdehyde levels were evaluated. Results: Our results indicated that after one hour incubation, ascorbic acid significantly reduced malondialdehyde level in ascorbic acid group (1.4±0.11 nmol/ml) compared to control group (1.58±0.13 nmol/ml) (p<0.001). At the end of incubation, progressive motility and viability in ascorbic acid group (64.5±8.8% and 80.3±6.4%, respectively) were significantly (p<0.05 and p<0.001, respectively) higher than the control group (54.5±6.8% and 70.9±7.3%, respectively). A23187 significantly (p<0.0001) increased acrosome reaction in A23187 group (37.3±5.6%) compared to control group (8.5±3.2%) and this effect of A23187 attenuated by ascorbic acid in ascorbic acid+A23187 group (17.2±4.4%). DNA fragmentation in ascorbic acid group (20±4.1%) was significantly (p<0.001) lower than controls (28.9±4.6%). Conclusion: In vitro ascorbic acid supplementation during teratozoospermic semen processing for ART could protect teratozoospermic specimens against oxidative stress, and it could improve ART outcome. PMID:24799867

  6. Mechanistic insights into a BINOL-derived phosphoric acid-catalyzed asymmetric Pictet-Spengler reaction

    E-print Network

    Overvoorde, Lois M.; Grayson, Matthew N.; Luo, Yi; Goodman, Jonathan M.

    2015-02-05

    Mechanistic Insights into a BINOL-Derived Phosphoric Acid- Catalyzed Asymmetric Pictet?Spengler Reaction Lois M. Overvoorde,† Matthew N. Grayson,† Yi Luo,§ and Jonathan M. Goodman*,† †Centre for Molecular Informatics, Department of Chemistry... unrestricted use, distribution and reproduction in any medium, provided the author and source are cited. considerably higher in energy than the five- and six-membered ring formation TSs. They therefore concluded that the five- membered intermediate would not go...

  7. Isotope Effects and Mechanism of the Asymmetric BOROX Brønsted Acid Catalyzed Aziridination Reaction

    PubMed Central

    Vetticatt, Mathew J.; Desai, Aman A.; Wulff, William D.

    2013-01-01

    The mechanism of the chiral VANOL-BOROX Brønsted acid catalyzed aziridination reaction of imines and ethyldiazoacetate has been studied using a combination of experimental kinetic isotope effects and theoretical calculations. A stepwise mechanism where reversible formation of a diazonium ion intermediate precedes rate-limiting ring-closure to form the cis-aziridine is implicated. A revised model for the origin of enantio- and diastereoselectivity is proposed based on relative energies of the ring closing transition structures. PMID:23687986

  8. Reaction zone structures and propagation mechanisms of flames in stearic acid particle clouds

    Microsoft Academic Search

    Wen-Jun Ju; Ritsu Dobashi; Toshisuke Hirano

    1998-01-01

    Reaction zone structures and propagation mechanisms of two representative flames established in stearic acid (CH3(CH2)16CO2H) particle clouds have been investigated. The reacting zone structure was examined by using a micro-electrostatic probe and a high-speed schlieren system. A distinct difference was observed in the ion current fluctuations recorded across the two representative flames propagating through the clouds of the same total

  9. Controlled accessibility Lewis acid catalysed thermal reactions of regenerated cellulosic fibres

    Microsoft Academic Search

    Dimtra Domvoglou; Franz Wortmann; Jim Taylor; Roger Ibbett

    2010-01-01

    A combination of techniques have been used to characterise lyocell regenerated cellulose fibre subjected to low-moisture thermal-catalytic\\u000a reactions with zinc chloride Lewis acid. Application from non-swelling ethanol reduces catalyst accessibility, but at high\\u000a temperatures migration takes place through the internal fibre morphology. The extent of chain scission is reduced at lower\\u000a temperatures, leading to a higher leveling-off degree of polymerisation

  10. Preparation of leady oxide for lead–acid battery by cementation reaction

    Microsoft Academic Search

    Joon-Ho Shin; Ki-Won Kim; Hyo-Jun Ahn

    2000-01-01

    The aim of this research is to prepare leady oxide with high specific area for lead–acid batteries by a new production process. Leady oxide is produced by a cementation reaction in 1.0 wt% HCl solution using a pure aluminum or a magnesium rod as the reductant. Leady oxide prepared in this process is much superior to Barton-pot or ball-mill oxide

  11. Simulation of AcidBase Reactions in a Microscale Confined Impinging Jet Reactor

    Microsoft Academic Search

    Jen Olsen; Lucas Griffith; Michael Olsen; Rodney Fox

    2009-01-01

    Numerical simulations were performed of reactive mixing in a microscale confined impinging jets reactor (CIJR). A simple acid-base reaction was modeled and solved for a laminar flow case. Local pH throughout the reactor was determined as a function of hydrogen and hydroxide mixture fraction, and this relationship was used to generate a pH field that could be compared with experimental

  12. Heterogeneous reactions in sulfuric acid aerosols: A framework for model calculations

    SciTech Connect

    Hanson, D.R.; Ravishankara, A.R.; Solomon, S. [National Oceanic and Atmospheric Administration, Boulder, CO (United States)] [National Oceanic and Atmospheric Administration, Boulder, CO (United States); [Univ. of Colorado, Boulder, CO (United States)

    1994-02-20

    A framework for applying rates of heterogeneous chemical reactions measured in the laboratory to small sulfuric acid aerosols found in the stratosphere is presented. The procedure for calculating the applicable reactive uptake coefficients using laboratory-measured parameters is developed, the necessary laboratory-measured quantities are discussed, and a set of equations for use in models are presented. This approach is demonstrated to be essential for obtaining uptake coefficients for the HOCl+HCl and ClONO{sub 2}+HCl reactions applicable to the stratosphere. In these cases the laboratory-measured uptake coefficients have to be substantially corrected for the small size of the atmospheric aerosol droplets. The measured uptake coefficients for N{sub 2}O{sub 5}+H{sub 2}O and ClONO{sub 2}+H{sub 2}O as well as those for other heterogeneous reactions are discussed in the context of this model. Finally, the derived uptake coefficients were incorporated in two-dimensional dynamical and photochemical model. Thus for the first time the HCl reactions in sulfuric acid have been included. Substantial direct chlorine activation and consequent ozone destruction is shown to occur due to heterogeneous reactions involving HCl for volcanically perturbed aerosol conditions at high latitudes. Smaller but significant chlorine activation also is predicted for background sulfuric acid aerosol in these regions. The coupling between homogeneous and heterogeneous chemistry is shown to lead to important changes in the concentrations of various reactive species. The basic physical and chemical quantities needed to better constrain the model input parameters are identified. 39 refs., 10 figs., 4 tabs.

  13. A preliminary investigation of acid-catalyzed polymerization reactions of shale oil distillates

    SciTech Connect

    Netzel, D.A.

    1991-04-01

    Sinor (1989) reported that a major specialty market may exist for shale oil as an asphalt blending material. Shale oil can be converted to an asphalt blending material by acid catalyzed condensation and polymerization reactions of the many molecular species comprising the composition of shale oil. To simplify the investigation, crude shale oil was separated by distillation into three distillates of different hydrocarbon and heteroaromatic compositions. These distillates were then treated with two different types of acids to determine the effect of acid type on the end products. Three western shale oil distillates, a naphtha, a middle distillate, and an atmospheric gas oil, were reacted with anhydrous AlCl{sub 3} and 85% H{sub 2}SO{sub 4} under low-severity conditions. At relatively low temperatures, little change in the hydrocarbon composition was noted for the AlCl{sub 3} reactions. AlCl{sub 3}{center_dot} (a polymerized product and/or complex) was formed. However, it is assumed that the sludge was mainly the result of heteroaromatic-AlCl{sub 3} reactions.

  14. A preliminary investigation of acid-catalyzed polymerization reactions of shale oil distillates

    SciTech Connect

    Netzel, D.A.

    1991-04-01

    Sinor (1989) reported that a major specialty market may exist for shale oil as an asphalt blending material. Shale oil can be converted to an asphalt blending material by acid catalyzed condensation and polymerization reactions of the many molecular species comprising the composition of shale oil. To simplify the investigation, crude shale oil was separated by distillation into three distillates of different hydrocarbon and heteroaromatic compositions. These distillates were then treated with two different types of acids to determine the effect of acid type on the end products. Three western shale oil distillates, a naphtha, a middle distillate, and an atmospheric gas oil, were reacted with anhydrous AlCl{sub 3} and 85% H{sub 2}SO{sub 4} under low-severity conditions. At relatively low temperatures, little change in the hydrocarbon composition was noted for the AlCl{sub 3} reactions. AlCl{sub 3}{center dot} (a polymerized product and/or complex) was formed. However, it is assumed that the sludge was mainly the result of heteroaromatic-AlCl{sub 3} reactions.

  15. Reverse reaction of malic enzyme for HCO3- fixation into pyruvic acid to synthesize L-malic acid with enzymatic coenzyme regeneration.

    PubMed

    Ohno, Yoko; Nakamori, Toshihiko; Zheng, Haitao; Suye, Shin-ichiro

    2008-05-01

    Malic enzyme [L-malate: NAD(P)(+) oxidoreductase (EC 1.1.1.39)] catalyzes the oxidative decarboxylation of L-malic acid to produce pyruvic acid using the oxidized form of NAD(P) (NAD(P)(+)). We used a reverse reaction of the malic enzyme of Pseudomonas diminuta IFO 13182 for HCO(3)(-) fixation into pyruvic acid to produce L-malic acid with coenzyme (NADH) generation. Glucose-6-phosphate dehydrogenase (EC1.1.1.49) of Leuconostoc mesenteroides was suitable for coenzyme regeneration. Optimum conditions for the carboxylation of pyruvic acid were examined, including pyruvic acid, NAD(+), and both malic enzyme and glucose-6-phosphate dehydrogenase concentrations. Under optimal conditions, the ratio of HCO(3)(-) and pyruvic acid to malic acid was about 38% after 24 h of incubation at 30 degrees C, and the concentration of the accumulated L-malic acid in the reaction mixture was 38 mM. The malic enzyme reverse reaction was also carried out by the conjugated redox enzyme reaction with water-soluble polymer-bound NAD(+). PMID:18460807

  16. Fabrication of Uniform DNA-Conjugated Hydrogel Microparticles via Replica Molding for Facile Nucleic Acid Hybridization Assays

    PubMed Central

    Lewis, Christina L.; Choi, Chang-Hyung; Lin, Yan; Lee, Chang-Soo; Yi, Hyunmin

    2010-01-01

    We identify and investigate several critical parameters in the fabrication of single-stranded DNA conjugated poly(ethylene glycol) (PEG) microparticles based on replica molding (RM) for highly uniform and robust nucleic acid hybridization assays. The effects of PEG-diacrylate, probe DNA, and photoinitiator concentrations on the overall fluorescence and target DNA penetration depth upon hybridization are examined. Fluorescence and confocal microscopy results illustrate high conjugation capacity of probe and target DNA, femtomole sensitivity, and sequence specificity. Combined these findings demonstrate a significant step toward simple, robust, and scalable procedures to manufacture highly uniform and high capacity hybridization assay particles in a well-controlled manner by exploiting many advantages that the batch processing-based RM technique offers. We envision that the results presented here may be readily applied to rapid and high throughput hybridization assays for a wide variety of applications in bioprocess monitoring, food safety, and biological threat detection. PMID:20527819

  17. A re-investigation of the reaction of hemimellitic acid with sulphur tetrafluoride. A simple preparation of 2,6-bis(trifluoromethyl)benzoic acid

    Microsoft Academic Search

    Wojciech Dmowski; Wojciech Wiszniewski

    1997-01-01

    The reaction of hemimellitic acid (1) with SF4\\/HF gives a 1 : 3.5 : 13 mixture of 1,2,3-tris (trifluoromethyl) benzene (2), 1,1,3,3-tetrafluoro 4-trifluoromethyl-l, 3-dihydroisobenzofuran (3) and 2,6-bis(trifluoromethyl)benzoyl fluoride (4). Treatment of the crude reaction mixture with aqueous KOH, followed by acidification of the water phase, gives a good yield of pure 2,6-bis(trifluoromethyl)benzoic acid (5).

  18. UV filter decomposition. A study of reactions of 4-(2-aminophenyl)-4-oxocrotonic acid with amino acids and antioxidants present in the human lens

    Microsoft Academic Search

    Lyudmila V. Kopylova; Olga A. Snytnikova; Elena I. Chernyak; Sergey V. Morozov; Yuri P. Tsentalovich

    2007-01-01

    Deamination of UV filters, such as kynurenine (KN), in the human lens results in protein modification. Thermal reactions of the product of kynurenine deamination, 4-(2-aminophenyl)-4-oxocrotonic acid (CKA), with amino acids (histidine, lysine, methionine, tryptophan, tyrosine, cysteine) and antioxidants (ascorbate, NADH, glutathione reduced) were studied. The rate constants of the reactions under physiological conditions were measured. The rate constants of CKA

  19. On the reaction of lupulones, hops ?-acids, with 1-hydroxyethyl radical.

    PubMed

    de Almeida, Natália E C; do Nascimento, Eduardo S P; Cardoso, Daniel R

    2012-10-24

    Lupulones, hops ?-acids, are one of the main constituents of the hops resin and have an important contribution to the overall bacteriostatic activity of hops during beer brewing. The use of lupulones as natural alternatives to antibiotics is increasing in the food industry and also in bioethanol production. However, lupulones are easy oxidizable and have been shown to be very reactive toward 1-hydroxyethyl radical with apparent bimolecular rate constants close to diffusion control k = 2.9 × 10(8) and 2.6 × 10(8) L mol(-1) s(-1) at 25.0 ± 0.2 °C in ethanol-water solution (10% of ethanol (v/v)) as probed by EPR and ESI-IT-MS/MS spin-trapping competitive kinetics, respectively. The free energy change for an electron-transfer mechanism is ?G° = 106 kJ/mol as calculated from the oxidation peak potential experimentally determined for lupulones (1.1 V vs NHE) by cyclic voltammetry and the reported reduction potential for 1-hydroxyethyl radical. The major reaction products identified by LC-ESI-IT-MS/MS and ultrahigh-resolution accurate mass spectrometry (orbitrap FT-MS) are hydroxylated lupulone derivatives and 1-hydroxyethyl radical adducts. The lack of pH dependence for the reaction rate constant, the calculated free energy change for electron transfer, and the main reaction products strongly suggest the prenyl side chains at the hops ?-acids as the reaction centers rather than the ?,?'-triketone moiety. PMID:23031058

  20. EXAFS Study on the Reactions Between Iron And Fulvic Acid in Acid Aqueous Solutions

    SciTech Connect

    Schaik, J.W.J.van; Persson, I.; Kleja, D.B.; Gustafsson, J.P.

    2009-05-26

    Iron(III) competes with trace metals for binding sites on organic ligands. We used X-ray absorption fine structure (EXAFS) spectroscopy to determine the binding mode and oxidation state of iron in solutions initially containing only iron(III) and fulvic acid at pHs 2 and 4. EXAFS spectra were recorded at different times after sample preparation. Iron was octahedrally configured with inner-sphere Fe-O interactions at 1.98-2.10 {angstrom}, depending on the oxidation state of iron. Iron(III) formed complexes with fulvic acid within 15 min. Iron(III) was reduced to iron(II) with time at pH 2, whereas no significant reduction occurred at pH 4. No signs of dimeric/trimeric hydrolysis products were found in any of the solution samples (<0.45 {mu}m). However, the isolated precipitate of the pH 2 sample (>0.45 {mu}m) showed Fe{hor_ellipsis}Fe distances, indicating the presence of tightly packed iron(III) trimers and/or clusters of corner-sharing octahedra. It is suggested that the binding mode of iron(III) to fulvic acid at low pH may be phase-dependent: in solution mononuclear complexes predominate, whereas in the solid phase hydrolyzed polynuclear iron(III) complexes form, even at very low pH values. The observed pH dependence of iron(III) reduction was consistent with expected results based on thermodynamic calculations for model ligands.

  1. Ethylene Glycol-Citric Acid-Silica Hybrid Organic-Inorganic Materials Obtained by the Sol-Gel Method

    Microsoft Academic Search

    A. Campero; Judith Cardoso; S. Pacheco

    1997-01-01

    The combination of inorganic polymeric networks with organic molecules leads to hybrid materials. Tetraethoxysilane (TEOS) was used as the precursor for the inorganic component, covalently bonded to ethylene glycol (EG) and citric acid (CA) molecules, whose esterification provides the in situ water for hydrolysis of TEOS. Ethanol was added in various amounts to the TEOS-EG-CA mixtures in order to induce

  2. Microbial populations identified by fluorescence in situ hybridization in a constructed wetland treating acid coal mine drainage

    Microsoft Academic Search

    Duongruitai Nicomrat; Warren A. Dick; Olli H. Tuovinen

    2006-01-01

    Microorganisms are an integral part of the biogeochemical processes in wetlands, yet microbial communities in sediments within constructed wetlands receiving acid mine drainage (AMD) are only poorly understood. The purpose of this study was to characterize the microbial diversity and abundance in a wetland receiving AMD using fluorescence in situ hybridization (FISH) analysis. Seasonal samples of oxic surface sediments, comprised

  3. Both n-6 and n-3 Fatty Acids Are Required for Maximal Growth of Juvenile Hybrid Tilapia

    Microsoft Academic Search

    Ben-Shan Chou; Shi-Yen Shiau

    1999-01-01

    An 8-week feeding experiment was conducted to provide preliminary information on essential fatty acid requirements of hybrid tilapia (female Nile tilapia Oreochromis niloticus × male blue tilapia O. aureus). Seven semipurified diets containing 30% crude protein from casein with 3.2 kcal available energy\\/g were supplemented with 5% of either lard (L), corn oil (C), cod liver oil (F), lard and

  4. Development of rapeseed with high erucic acid content by asymmetric somatic hybridization between Brassica napus and Crambe abyssinica

    Microsoft Academic Search

    Y. P. Wang; K. Sonntag; E. Rudloff

    2003-01-01

    PEG-induced asymmetric somatic hybridization between Brassica napus and Crambe abyssinica was carried out. C. abyssinica is an annual cruciferous oil crop with a high content of erucic acid in the seed oil valuable for technical purposes. UV-irradiated mesophyll protoplasts of C. abyssinica cv 'Carmen' and cv 'Galactica' were fused with hypocotyl protoplasts of different genotypes of B. napus cv 'Maplus'

  5. Nucleic acid hybridization studies on Microbacterium, Curtobacterium, Agromyces and related taxa.

    PubMed

    Döpfer, H; Stackebrandt, E; Fiedler, F

    1982-08-01

    Thirty strains of Agromyces, Arthrobacter, Curtobacterium, Brevibacterium, Corynebacterium and Microbacterium, exhibiting the rare peptidoglycan of group B, were subjected to extensive nucleic acid hybridization studies. The DNA homology values indicate that Corynebacterium insidiosum DSM 20157 is genetically identical with Corynebacterium michiganense DSM 20134. Corynebacterium sepedonicum NCPPB 378 and Corynebacterium nebraskense DSM 20400 are closely related to Corynebacterium michiganense DSM 20134. Corynebacterium betae DSM 20141, Corynebacterium oortii ATCC 25283 and Corynebacterium poinsettiae ATCC 9682 are genetically identical with Corynebacterium flaccumfaciens DSM 20129. In addition, Curtobacterium citreum ATCC 15828, Curtobacterium luteum ATCC 15830 and Curtobacterium pusillum ATCC 19096 share a high degree of relatedness to Corynebacterium flaccumfaciens DSM 20129. All other described species are more distantly related to each other. DNa-rRNA cistron similarity studies reveal that all corynebacterium with a peptidoglycan group B are members of one homogeneous cluster for which the rank of a genus is suggested. PMID:6183393

  6. A hybrid variational-perturbation calculation of the ro-vibrational spectrum of nitric acid

    E-print Network

    Pavlyuchko, A I; Tennyson, Jonathan

    2014-01-01

    Rotation-vibration spectra of the nitric acid molecule, HNO\\3, are calculated for wavenumbers up to 7000~\\cm. Calculations are performed using a Hamiltonian expressed in internal curvilinear vibrational coordinates solved using a hybrid variational-perturbation method. An initial potential energy surface (PES) and dipole moment function (DMF) are calculated {\\it ab initio} at the CCSD(T)/aug-cc-pVQZ level of theory. Parameters of the PES and DMF are varied to minimize differences between the calculated and experimental transition frequencies and intensities. The average, absolute deviation between calculated and experimental values is 0.2~\\cm\\ for frequencies in the fundamental bands and 0.4~\\cm\\ for those in the first overtone and lowest combination bands. For the intensities, the calculated and experimental values differ by 0.3\\% and 40\\% for the fundamentals and overtones, respectively. The optimized PES and DMF are used to calculate the room-temperature ro-vibrational spectrum. These calculation reproduce...

  7. Reaction of argininosuccinase with bromomesaconic acid: role of an essential lysine in the active site

    SciTech Connect

    Lusty, C.J.; Ratner, S.

    1987-05-01

    We have undertaken studies on bovine liver argininosuccinase (L-argininosuccinate arginine-lyase with the active site-directed reagent bromo(U-/sup 14/C)mesaconic acid, an analogue of fumaric acid. Reactivity, measured by enzyme inactivation, followed pseudo-first-order kinetics, and the rate increased with reagent concentration. Argininosuccinate completely protected the enzyme against inactivation, but neither arginine nor fumarate was protective. A plot of the degree of inactivation as a function of alkyl groups incorporated was extrapolated to 4 mol per mol of enzyme, or 1 mol per active site. After large-scale alkylation of the enzyme (and digestion with trypsin), two /sup 14/C-labeled tryptic peptides were isolated. These were chemically sequenced by the Edman method. The amino acid sequences proved to be identical with regions of the deduced amino acid sequences or argininosuccinases from human and yeast sources The /sup 14/C-labeled tryptic peptide in the active site region had the sequence Gly-Leu-Glu-Xaa-Ala-Gly-Leu-Leu-Thr-Lys; Xaa represents an unknown phenylthiohydantoin derivative detected in cycle 4. The corresponding amino acid was identified as lysine-51 on the basis of sequence similarity with human and yeast amino acid sequences in this region. The reaction of the enzyme with the alkylating agent and the specific protection against inactivation by argininosuccinate suggest that this lysine residue has an essential role in the binding of argininosuccinate to the enzyme and, consequently, is essential for catalysis.

  8. REACTION MECHANISMS OF 15-HYDROPEROXYEICOSATETRAENOIC ACID CATALYZED BY HUMAN PROSTACYCLIN AND THROMBOXANE SYNTHASES

    PubMed Central

    Yeh, Hui-Chun; Tsai, Ah-Lim; Wang, Lee-Ho

    2007-01-01

    Prostacyclin synthase (PGIS) and thromboxane synthase (TXAS) are atypical cytochrome P450s. They do not require NADPH or dioxygen for isomerization of prostaglandin H2 (PGH2) to produce prostacyclin (PGI2) and thromboxane A2 (TXA2). PGI2 and TXA2 have opposing actions on platelet aggregation and blood vessel tone. In this report, we use a lipid hydroperoxide, 15-hydroperoxyeicosatetraenoic acid (15-HPETE), to explore the active site characteristics of PGIS and TXAS. The two enzymes transformed 15-HPETE not only into 13-hydroxy-14,15-epoxy-5,8,11-eicosatrienoic acid (13-OH-14,15-EET), like many microsomal P450s, but also to 15-ketoeicosatetraenoic acid (15-KETE) and 15-hydroxyeicosatetraenoic acid (15-HETE). 13-OH-14,15-EET and 15-KETE result from homolytic cleavage of the O–O bond, whereas 15-HETE results from heterolytic cleavage, a common peroxidase pathway. About 80% of 15-HPETE was homolytically cleaved by PGIS and 60% was homolytically cleaved by TXAS. The Vmax of homolytic cleavage is 3.5-fold faster than heterolytic cleavage for PGIS-catalyzed reactions (1100 min?1 vs. 320 min?1) and 1.4-fold faster for TXAS (170 min?1 vs. 120 min?1). Similar KM values for homolytic and heterolytic cleavages were found for PGIS (?60 ?M 15-HPETE) and TXAS (?80 ?M 15-HPETE), making PGIS a more efficient catalyst for the 15-HPETE reaction. PMID:17459323

  9. Nuclemeter: A Reaction-Diffusion Based Method for Quantifying Nucleic Acids Undergoing Enzymatic Amplification

    PubMed Central

    Liu, Changchun; Sadik, Mohamed M.; Mauk, Michael G.; Edelstein, Paul H.; Bushman, Frederic D.; Gross, Robert; Bau, Haim H.

    2014-01-01

    Real-time amplification and quantification of specific nucleic acid sequences plays a major role in medical and biotechnological applications. In the case of infectious diseases, such as HIV, quantification of the pathogen-load in patient specimens is critical to assess disease progression and effectiveness of drug therapy. Typically, nucleic acid quantification requires expensive instruments, such as real-time PCR machines, which are not appropriate for on-site use and for low-resource settings. This paper describes a simple, low-cost, reaction-diffusion based method for end-point quantification of target nucleic acids undergoing enzymatic amplification. The number of target molecules is inferred from the position of the reaction-diffusion front, analogous to reading temperature in a mercury thermometer. The method was tested for HIV viral load monitoring and performed on par with conventional benchtop methods. The proposed method is suitable for nucleic acid quantification at point of care, compatible with multiplexing and high-throughput processing, and can function instrument-free. PMID:25477046

  10. Aquatic photolysis: photolytic redox reactions between goethite and adsorbed organic acids in aqueous solutions

    USGS Publications Warehouse

    Goldberg, M.C.; Cunningham, K.M.; Weiner, Eugene R.

    1993-01-01

    Photolysis of mono and di-carboxylic acids that are adsorbed onto the surface of the iron oxyhydroxide (goethite) results in an oxidation of the organic material and a reduction from Fe(III) to Fe(II) in the iron complex. There is a subsequent release of Fe2+ ions into solution. At constant light flux and constant solution light absorption, the factors responsible for the degree of photolytic reaction include: the number of lattice sites that are bonded by the organic acid; the rate of acid readsorption to the surface during photolysis; the conformation and structure of the organic acid; the degree of oxidation of the organic acid; the presence or absence of an ??-hydroxy group on the acid, the number of carbons in the di-acid chain and the conformation of the di-acid. The ability to liberate Fe(III) at pH 6.5 from the geothite lattice is described by the lyotropic series: tartrate>citrate> oxalate > glycolate > maleate > succinate > formate > fumarate > malonate > glutarate > benzoate = butanoate = control. Although a larger amount of iron is liberated, the series is almost the same at pH 5.5 except that oxalate > citrate and succinate > maleate. A set of rate equations are given that describe the release of iron from the goethite lattice. It was observed that the pH of the solution increases during photolysis if the solutions are not buffered. There is evidence to suggest the primary mechanism for all these reactions is an electron transfer from the organic ligand to the Fe(III) in the complex. Of all the iron-oxyhydroxide materials, crystalline goethite is the least soluble in water; yet, this study indicates that in an aqueous suspension, iron can be liberated from the goethite lattice. Further, it has been shown that photolysis can occur in a multiphase system at the sediment- water interface which results in an oxidation of the organic species and release of Fe2+ to solution where it becomes available for further reaction. ?? 1993.

  11. Survivability and Abiotic Reactions of Selected Amino Acids in Different Hydrothermal System Simulators

    NASA Astrophysics Data System (ADS)

    Chandru, Kuhan; Imai, Eiichi; Kaneko, Takeo; Obayashi, Yumiko; Kobayashi, Kensei

    2013-04-01

    We tested the stability and reaction of several amino acids using hydrothermal system simulators: an autoclave and two kinds of flow reactors at 200-250 °C. This study generally showed that there is a variation in the individual amino acids survivability in the simulators. This is mainly attributed to the following factors; heat time, cold quenching exposure, metal ions and also silica. We observed that, in a rapid heating flow reactor, high aggregation and/or condensation of amino acids could occur even during a heat exposure of 2 min. We also monitored their stability in a reflow-type of simulator for 120 min at 20 min intervals. The non-hydrolyzed and hydrolyzed samples for this system showed a similar degradation only in the absence of metal ions.

  12. Templated Synthesis of Peptide Nucleic Acids via Sequence-Selective Base-Filling Reactions

    PubMed Central

    2009-01-01

    The templated synthesis of nucleic acids has previously been achieved through the backbone ligation of preformed nucleotide monomers or oligomers. In contrast, here we demonstrate templated nucleic acid synthesis using a base-filling approach in which individual bases are added to abasic sites of a peptide nucleic acid (PNA). Because nucleobase substrates in this approach are not self-reactive, a base-filling approach may reduce the formation of nontemplated reaction products. Using either reductive amination or amine acylation chemistries, we observed efficient and selective addition of each of the four nucleobases to an abasic site in the middle of the PNA strand. We also describe the addition of single nucleobases to the end of a PNA strand through base filling, as well as the tandem addition of two bases to the middle of the PNA strand. These findings represent an experimental foundation for nonenzymatic information transfer through base filling. PMID:19722647

  13. Acid-base chemical reaction model for nucleation rates in the polluted atmospheric boundary layer

    NASA Astrophysics Data System (ADS)

    Chen, Modi; Titcombe, Mari; Jiang, Jingkun; Jen, Coty; Kuang, Chongai; Fischer, Marc L.; Eisele, Fred L.; Siepmann, J. Ilja; Hanson, David R.; Zhao, Jun; McMurry, Peter H.

    2013-05-01

    Measurements of aerosol number distributions down to one molecule have provided information that we've used to develop a new approach for modeling atmospheric nucleation rates. Measurements were carried out with the Cluster Chemical Ionization Mass Spectrometer (Cluster CIMS), the scanning mobility spectrometer using a diethylene glycol condensation particle counter as detector (DEG SMPS), and an ambient pressure proton transfer mass spectrometer for ammonia and amines (AmPMS). The model explains nucleation as a result of cluster evolution due to a sequence of acid-base reactions. We conclude that the smallest stable cluster contains four sulfuric acid molecules. The model leads to a simple analytic expression for nucleation rates that is reasonably consistent (i.e., ± 10x) with atmospheric observations. The model predicts that nucleation rates are equal to a prefactor, P<1, times the sulfuric acid vapor collision rate, (i.e., J=P?0.5?k11 *[H2SO4]2).

  14. Nonenzymatic oligomerization reactions on templates containing inosinic acid or diaminopurine nucleotide residues

    NASA Technical Reports Server (NTRS)

    Kozlov, I. A.; Orgel, L. E.; Bada, J. L. (Principal Investigator)

    1999-01-01

    The template-directed oligomerization of nucleoside-5'-phosphoro-2-methyl imidazolides on standard oligonucleotide templates has been studied extensively. Here, we describe experiments with templates in which inosinic acid (I) is substituted for guanylic acid, or 2,6-diaminopurine nucleotide (D) for adenylic acid. We find that the substitution of I for G in a template is strongly inhibitory and prevents any incorporation of C into internal positions in the oligomeric products of the reaction. The substitution of D for A, on the contrary, leads to increased incorporation of U into the products. We found no evidence for the template-directed facilitation of oligomerization of A or I through A-I base pairing. The significance of these results for prebiotic chemistry is discussed.

  15. Uptake of Small Organic Compounds by Sulfuric Acid Aerosols: Dissolution and Reaction

    NASA Technical Reports Server (NTRS)

    Iraci, L. T.; Michelsen, R. R.; Ashbourn, S. F. M.; Staton, S. J. R.

    2003-01-01

    To assess the role of oxygenated volatile organic compounds in the upper troposphere and lower stratosphere, the interactions of a series of small organic compounds with low-temperature aqueous sulfuric acid will be evaluated. The total amount of organic material which may be taken up from the gas phase by dissolution, surface layer formation, and reaction during the particle lifetime will be quantified. Our current results for acetaldehyde uptake on 40 - 80 wt% sulfuric acid solutions will be compared to those of methanol, formaldehyde, and acetone to investigate the relationships between chemical functionality and heterogeneous activity. Where possible, equilibrium uptake will be ascribed to component pathways (hydration, protonation, etc.) to facilitate evaluation of other species not yet studied in low temperature aqueous sulfuric acid.

  16. Stereoselective synthesis of unsaturated and functionalized L-NHBoc amino acids, using Wittig reaction under mild phase-transfer conditions.

    PubMed

    Rémond, Emmanuelle; Bayardon, Jérôme; Ondel-Eymin, Marie-Joëlle; Jugé, Sylvain

    2012-09-01

    The stereoselective synthesis of a new amino acid phosphonium salt was described by quaternization of melting triphenylphosphine with the ?-iodo NHBoc-amino ester, derived from L-aspartic acid. The deprotection of the carboxylic acid function to afford the phosphonium salt with a free carboxylic acid group was achieved by a palladium-catalyzed desallylation reaction. This phosphonium salt was used in the Wittig reaction with aromatic or aliphatic aldehydes and trifluoroacetophenone, under solid-liquid phase-transfer conditions in chlorobenzene and in the presence of K(3)PO(4) as weak base, to afford the corresponding unsaturated amino acids without racemization. Thus, the reaction with substituted aldehydes allows to graft various functionalized groups on the lateral chain of the amino acid, such as trifluoromethyl, cyano, nitro, ferrocenyl, boronato, or azido. In addition, the reaction of the amino acid Wittig reagent with ?,?-unsaturated aldehydes leads to amino acids bearing a diene on the lateral chain. Finally, this amino acid phosphonium salt appears to be a new powerful tool for the preparation of unsaturated and non-proteinogenic ?-amino acids, directly usable for the synthesis of customized peptides. PMID:22870957

  17. Gas phase proton transfer reaction of nitric acid-ammonia and the role of water

    NASA Astrophysics Data System (ADS)

    Tao, Fu-Ming

    1998-01-01

    The gas-phase proton transfer reaction of nitric acid-ammonia and the effect of the first three water molecules are investigated by high level ab initio calculations on the molecular clusters HNO3-NH3-(H2O)n, n=0,1,2,3. The equilibrium structures, binding energies, and harmonic frequencies of the clusters as well as the potential energy surfaces along the proton transfer pathway of nitric acid-ammonia are calculated at the second-order Møller-Plesset perturbation (MP2) level with two extended basis sets 6-31+G(d) and 6-311++G(d,p). It is found that, either without water or with one water molecule, the nitric acid-ammonia system exists as hydrogen bonded, with nitric acid acting as the hydrogen bond donor and ammonia as the acceptor. With two or three water molecules, the system becomes an ion pair resulting from the complete transfer of a proton from the nitric acid to ammonia. The potential energy surfaces along the proton transfer pathway are analyzed to understand the effect of the water molecules. The water molecules stepwise added into the system are found to increase the stability of the ion pair over the hydrogen bonded form. The first water molecule is not enough to stabilize the ion pair, but it results in a flatter potential energy pathway for the proton transfer. The second water molecule produces additional stabilization energy which helps fully stabilize the ion pair. The third water molecule contributes to further stabilize the ion pair. The harmonic frequencies and infrared intensities of the clusters are analyzed, which provide further evidence in agreement with the transition from the hydrogen bond to the ion pair structure as the water molecules are stepwise introduced. On the basis of these results, we conclude that ammonium nitrate might be formed by the gas phase reaction of nitric acid with ammonia in the presence of adequate water vapor.

  18. Reduction of inflammatory reaction of poly(d,l-lactic-co-glycolic Acid) using demineralized bone particles.

    PubMed

    Yoon, Sun Jung; Kim, Soon Hee; Ha, Hyun Jung; Ko, Youn Kyung; So, Jung Won; Kim, Moon Suk; Yang, Young Il; Khang, Gilson; Rhee, John M; Lee, Hai Bang

    2008-04-01

    Poly(lactide-co-glycolic acid) (PLGA) has been widely applied to tissue engineering as a good biocompatible material because of its biodegradability and nontoxic metabolites, but how the inflammatory reaction of PLGA on the surrounding tissue in vivo is reduced has not been discussed sufficiently. We hypothesized that the cells neighboring the PLGA implant might have an inflammatory response that could be reduced by impregnating demineralized bone particles (DBPs) into the PLGA. We manufactured five different ratios of DBP/PLGA hybrid materials, with each material containing 0, 10, 20, 40, and 80 wt% of DBPs of PLGA. For biocompatibility test, NIH/3T3 mouse fibroblasts were cultured on the DBP/PLGA scaffold for 3 days. The inflammatory potential of PLGA was evaluated using messenger ribonucleic acid expression of tumor necrosis factor alpha (TNF-alpha) and interleukin 1-beta (IL-1beta) on a human acute promyelocytic leukemic cell (HL-60). The in vivo response of DBP/PLGA film was compared with that of PLGA film implanted subcutaneously; the local inflammatory response was observed according to histology. The DBP/PLGA scaffold had no adverse effect on NIH/3T3 initial cell attachment and did not affect cell viability. DBP/PLGA films, especially PLGA films containing 80% DBP, elicited a significantly lower expression of IL-1beta and TNF-alpha from HL-60 cells than PLGA film alone. In vivo, DBP/PLGA film demonstrated a more favorable tissue response profile than PLGA film, with significantly less inflammation and fibrous capsule formation as below only 20% of DBP in PLGA film during implantation. This study shows that application of DBPs reduces the fibrous tissue encapsulation and foreign body giant cell response that commonly occurs at the interface of PLGA. PMID:18352826

  19. Intertribal somatic hybrids between Brassica napus and Camelina sativa with high linolenic acid content

    Microsoft Academic Search

    J. J. Jiang; X. X. Zhao; W. Tian; T. B. Li; Y. P. Wang

    2009-01-01

    Intertribal somatic hybrids of Brassica napus and Camelina sativa were developed by protoplast electrofusion. Hybrid identity of the regenerants was determined using flow cytometric analysis\\u000a of nuclear DNA content and simple sequence repeat (SSR) marker analysis. Three hybrids exhibited specific bands for B. napus and C. sativa. These hybrids showed intermediate leaf, flower and seed morphology compared with the two

  20. Identification of Frankia strains in nodules by hybridization of polymerase chain reaction products with strain-specific oligonucleotide probes.

    PubMed

    Simonet, P; Normand, P; Moiroud, A; Bardin, R

    1990-01-01

    A set of oligonucleotides has been developed to study the competitivity of two Frankia strains in the nodulation of the roots of two host plant species: Alnus glutinosa and Alnus incana. Two 20 mer-oligonucleotides, complementary to highly conserved sequences inside the nifH gene, were used as primers for the polymerase chain reaction (PCR) system in order to amplify microsymbiont DNA extracted from actinorhizae. PCR products were analyzed using two strain-specific 15-mer oligonucleotides identified in the amplified region. Hybridization data indicate that strain ACoN24d is more competitive than strain ArI3 in the nodulation of both hosts. PMID:2334247

  1. DNA Surface Hybridization Regimes

    NASA Astrophysics Data System (ADS)

    Levicky, Rastislav; Gong, Ping

    2008-03-01

    Surface hybridization reactions, in which sequence-specific recognition occurs between immobilized and solution nucleic acids, are routinely carried out to quantify and to interpret genomic information. At a surface, molecular interactions are amplified by the two-dimensional nature of the immobilized layer which focuses the nucleic acid charge and concentration to levels not encountered in solution, and which impacts the hybridization behavior in unique ways. We find that, at low ionic strengths, an electrostatic balance between the concentration of immobilized oligonucleotide charge and solution ionic strength governs the onset of hybridization. As ionic strength increases, the importance of electrostatics diminishes and the hybridization behavior becomes more complex. Suppression of hybridization affinity constants relative to solution values, and their weakened dependence on the concentration of DNA counterions, indicate that the immobilized strands form complexes. Moreover, an unusual regime is observed in which the surface coverage of immobilized oligonucleotides does not significantly influence the hybridization behavior, despite physical closeness and hence compulsory interactions between sites. These results are interpreted and summarized in a diagram of hybridization regimes.

  2. Fatty acid and cholesterol composition of camel’s ( Camelus bactrianus, Camelus dromedarius and hybrids) milk in Kazakhstan

    Microsoft Academic Search

    Gaukhar Konuspayeva; Émilie Lemarie; Bernard Faye; Gérard Loiseau; Didier Montet

    2008-01-01

    The fatty acid composition and cholesterol content of 22 camel’s milk samples from different regions of Kazakhstan were determined,\\u000a in different seasons and with different camel species (Bactrian, dromedary and hybrids). Camel milk fat differed from mammalian\\u000a fats by its high content of the long-chain fatty acids C14:0, C16:0, C18:0 and C18:l. Great differences in fatty acid composition\\u000a occurred between

  3. Development of a lead-acid battery for a hybrid electric vehicle

    NASA Astrophysics Data System (ADS)

    Cooper, A.

    In September 2000, a project reliable, highly optimized lead-acid battery (RHOLAB) started under the UK Foresight Vehicle Programme with the objective of developing an optimized lead-acid battery solution for hybrid electric vehicles. The work is based on a novel, individual, spirally-wound valve-regulated lead-acid 2 V cell optimized for HEV use and low variability. This cell is being used as a building block for the development of a complete battery pack that is managed at the cell level. Following bench testing, this battery pack is to be thoroughly evaluated by substituting it for the Ni-MH pack in a Honda Insight. The RHOLAB cell is based on the 8 Ah Hawker Cyclon cell which has been modified to have current take-off at both ends—the dual-tab design. In addition, a variant has been produced with modified cell chemistry to help deal with problems that can occur when these valve-regulated lead-acid battery (VRLA) cells operate in a partial-state-of-charge condition. The cells have been cycled to a specially formulated test cycle based on real vehicle data derived from testing the Honda Insight on the various test tracks at the Millbrook Proving Grounds in the UK. These cycling tests have shown that the lead-acid pack can be successfully cycled when subjected to the high current demands from the vehicle, which have been measured at up to 15 C on discharge and 8 C during regenerative recharging, and cycle life is looking very promising under this arduous test regime. Concurrent with this work, battery development has been taking place. It was decided early on to develop the 144 V battery as four 36 V modules. Data collection and control has been built-in and special steps taken to minimize the problems of interconnect in this complex system. Development of the battery modules is now at an advanced stage. The project plan then allows for extensive testing of the vehicle with its lead-acid battery at Millbrook so it can be compared with the benchmark tests which have already been carried out on the vehicle with its Ni-MH batteries.

  4. Identification of amino acid residues important in the cyclization reactions of chalcone and stilbene synthases.

    PubMed Central

    Suh, D Y; Fukuma, K; Kagami, J; Yamazaki, Y; Shibuya, M; Ebizuka, Y; Sankawa, U

    2000-01-01

    Chalcone synthase (CHS) and stilbene synthase (STS) catalyse condensation reactions of p-coumaroyl-CoA and three C(2) units from malonyl-CoA up to a common tetraketide intermediate but then catalyse different cyclization reactions to produce naringenin chalcone and resveratrol respectively. On the basis of sequence alignment with other condensing enzymes including 3-ketoacyl-(acyl carrier protein) synthases of polyketide and fatty-acid synthases, site-directed mutagenesis was performed on the active-site G(372)FGPG loops in CHS and STS. The CHS-P375G mutant showed a 6-fold decrease in overall condensing activity with selectively increased production of p-coumaroyltriacetic acid lactone (CTAL, the derailment product of the tetraketide intermediate). Meanwhile, resveratrol production by STS-P(375)G strongly decreased to give various products in the order CTAL> resveratrol approximately bisnoryangonin>naringenin. As a result, naringenin production (cross-reaction) by STS-P(375)G was close to 30% of resveratrol production. Both G(374)L mutants of CHS and STS showed no condensing activity with residual malonyl-CoA decarboxylase activity. These results suggested that the G(372)FGPG loop in CHS and STS contribute to a determination of the outcome during cyclization reactions by serving as a part of the active-site scaffold on which the stereochemistry of cyclization is performed. These observations provide the first biochemical indication that cyclization reactions are modulated by active-site geometry. The implications for the evolutionary relationship of these enzymes are also discussed. PMID:10926848

  5. Preparation and Electrochemical Performance of Hybrid Materials Containing Heteropoly Acid with Dawson Structure and Polymers

    NASA Astrophysics Data System (ADS)

    Tong, Xia; Wu, Wen; Zhou, Shengming; Wu, Qingyin; Cao, Fahe; Yaroslavtsev, A. B.

    2012-11-01

    Highly proton-conducting hybrid materials (P2W17V/PEG and P2W17V/PEG/SiO2) were prepared by heptadecatungstovanadodiphosphoric heteropoly acid with Dawson structure (P2W17V, 90 wt.%), polyethylene glycol (PEG, 10 wt.% and 5 wt.%) and silica gel (SiO2, 0 wt.% and 5 wt.%). The products were characterized by the infrared (IR) spectrum, X-ray powder diffraction (XRD) analysis and electrochemical impedance spectrum (EIS). The result reveals that their conductivity values are 1.02 × 10-2 and 2.58 × 10-2S ? cm-1 at room temperature (26°C) and 75% relative humidity (RH), respectively. Their conductivities increase with higher temperature and these activation energies of proton conduction are 9.51 and 14.95 kJ?mol-1, which are lower than that of pure heteropoly acid (32.23 kJ?mol-1). These mechanisms of proton conduction for these two materials are Grotthuss mechanism.

  6. Poly(L-glutamic acid)-decorated hybrid colloidal particles from complex particle-templated silica mineralization.

    PubMed

    Shiu, Cheng Chang; Wang, Shuan; Chang, Chien-Hsiang; Jan, Jeng-Shiung

    2013-08-29

    We report the synthesis of polyelectrolyte complex (PEC) particles by mixing the negatively and positively charged polyelectrolytes, poly(L-glutamic acid) (PGA) and poly(2-(N,N-diethylamino) ethylmethacrylate) (PDEAEMA), and the use of negatively charged PEC particles as colloidal templates for silica mineralization under ambient conditions. The structure and property of PEC particles, as well as polypeptide chain conformation, were found to depend on the mixing weight percentage, polymer molecular weight, and solution condition. The negatively charged PEC micelles can be deposited with silica without loss colloid stability, leading to PGA-decorated hybrid particles. These hybrid particles were negatively charged at neutral and basic condition and become positively charged, accompanying the conformational changes of the grafted PGA, upon decreasing pH below isoelectric points due to the protonation/deprotonation of PGA and PDEAEMA. Functional nanoparticles such as gold NPs could be incorporated using polypeptides as the mediating agents. These hybrid particles loaded with drug exhibited noticeable pH-responsive behavior with accelerated release at acidic condition, demonstrating the potential for use as pH-responsive delivery vehicles. This type of polypeptide-decorated hybrid particles represents an interesting class of organic-inorganic hybrids in which the functional properties of polypeptides such as biocompatibility, stimuli responsiveness, and directed growth of metal nanoparticles can be incorporated. PMID:23822799

  7. Determination of rate constants for the reactions of H, OH and eaq with indole-3-acetic acid and other plant hormones

    Microsoft Academic Search

    R. S. Shetiya; K. N. Rao; J. Shankar

    1972-01-01

    In the radiolysis of aqueous solutions of indole, indole-3-acetic acid, indole-3-propionic acid, 1-naphthylacetic acid and phenylacetic acid, the absolute rate constants of their reactions with H and OH have been determined by competition kinetics using 2-propanol as the competitor. Hydrated electron reaction rate constants have been determined for indoie, indole-3-acetic acid and indole-3-propionic acid at pH = 11 using the

  8. Reactions of N,N-bis(2-chloroethyl)-p-aminophenylbutyric acid (chlorambucil) with 2'-deoxyadenosine.

    PubMed

    Florea-Wang, Diana; Haapala, Elina; Mattinen, Jorma; Hakala, Kristo; Vilpo, Juhani; Hovinen, Jari

    2003-03-01

    N,N-bis(2-chloroethyl)-p-aminophenylbutyric acid (chlorambucil, 1; 0.6 mM) was allowed to react with 2'-deoxyadenosine (16.1 mM) at physiological pH (cacodylic acid, 50% base), and the reactions were followed by HPLC-MS and HPLC-MS/MS techniques. Although the predominant reaction observed was chlorambucil hydrolysis, ca. 7% of 1 reacted with various heteroatoms of the nucleoside. The principal site of alkylation was N1. Several other adducts were also detected. The N1, N6, N3, and N7 derivatives were characterized by means of MS/MS, UV, and (1)H NMR. The N6 adduct is derived directly from alkylation of N6 of 2'-dAdo. Dimroth rearrangement of the N1 adduct to the N6 adduct was very slow under the reaction conditions employed. Minor adducts such as a carbohydrate derivative were tentatively characterized by MS/MS. No cross-links were detected. The role of chlorambucil-2'-deoxyadenosine adducts in the cytotoxicity and mutagenicity of 1 is also discussed. PMID:12641441

  9. Effect of acid concentration and pulp properties on hydrolysis reactions of mercerized sisal.

    PubMed

    Lacerda, Talita M; Zambon, Márcia D; Frollini, Elisabete

    2013-03-01

    The influence of sulfuric acid concentration (H2SO4 5-25%, 100°C), crystallinity and fibers size on the hydrolysis reaction of sisal pulps were investigated, with the goal of evaluating both the liquor composition, as an important step in the production of bioethanol, and the residual non-hydrolyzed pulp, to determine its potential application as materials. Aliquots were withdrawn from the reaction media, and the liquor composition was analyzed by HPLC. The residual non-hydrolyzed pulps were characterized by SEM, their average molar mass and crystallinity index, and their size distribution was determined using a fiber analyzer. Sulfuric acid 25% led to the highest glucose content (approximately 10gL(-1)), and this acid concentration was chosen to evaluate the influence of both the fiber size and crystallinity of the starting pulp on hydrolysis. The results showed that fibers with higher length and lower crystallinity favored glucose production in approximately 12%, with respect to the highly crystalline shorter fibers. PMID:23465940

  10. Initiation Temperature for Runaway Tri-n-Butyl Phosphate/Nitric Acid Reaction

    SciTech Connect

    Rudisill, T.S.

    2000-11-28

    During a review of the H-Canyon authorization basis, Defense Nuclear Facility Safety Board (DNFSB) staff members questioned the margin of safety associated with a postulated tri-n-butyl phosphate (TBP)/nitric acid runaway reaction due to the inadvertent heating of a canyon tank containing greater than 3000 lbs (1362 kg) of TBP. The margin of safety was partially based on experiments and calculations performed by the Actinide Technology Section (ATS) to support deletion of indication of tank agitation as a Safety Class System. In the technical basis for deletion of this system, ATS personnel conservatively calculated the equilibrium temperature distribution of a canyon tank containing TBP and nitric acid layers which were inadvertently heated by a steam jet left on following a transfer. The maximum calculated temperature (128 degrees C) was compared to the minimum initiation temperature for a runaway reaction (greater than 130 degrees C) documented by experimental work in the mid 195 0s. In this work, the initiation temperature as a function of nitric acid concentration was measured for 0 and 20 wt percent dissolved solids. The DNFSB staff members were concerned that data for 0 wt percent dissolved solids were not conservative given the facts that data for 20 wt percent dissolved solids show initiation temperatures at or below 130 degrees C and H-Canyon solutions normally contained a small amount of dissolved solids.

  11. Conversion of isoamyl alcohol over acid catalysts: Reaction dependence on nature of active centers

    SciTech Connect

    Babu, G.P.; Murthy, R.S.; Krishnan, V. [Hindustan Lever Research Centre, Bombay (India)] [Hindustan Lever Research Centre, Bombay (India)

    1997-02-01

    Acid catalysts are known to catalyze the dehydration of alcohols. In addition some oxide catalysts with basic properties have also been shown to play an important role in such dehydration reactions. The dehydration of aliphatic alcohols to olefins has been studied in detail using alumina silica-alumina and zeolite catalysts. The olefin products further undergo isomerization in presence of acidic sites. The reaction of isoamyl alcohol on catalytic surfaces has not been investigated in greater detail. The dehydration of isoamyl alcohol is of considerable interest in fine chemicals. Isoamyl alcohol may also undergo dehydrogenation as observed in the case of n-butanol. The scope of the present work is to identify the nature of the active sites selective for dehydration and dehydrogenation of isoamyl alcohol and to modify the active sites to promote isomerization of dehydrated products. Four catalytic surfaces on which the acidic strength can be varied, as well as selectively suppressed, are chosen for this study. 17 refs., 1 fig., 3 tabs.

  12. In situ DNA-hybridization chain reaction (HCR): a facilitated in situ HCR system for the detection of environmental microorganisms.

    PubMed

    Yamaguchi, Tsuyoshi; Kawakami, Shuji; Hatamoto, Masashi; Imachi, Hiroyuki; Takahashi, Masanobu; Araki, Nobuo; Yamaguchi, Takashi; Kubota, Kengo

    2015-07-01

    In situ detection of microorganisms by fluorescence in situ hybridization (FISH) is a powerful tool for environmental microbiology, but analyses can be hampered by low rRNA content in target organisms, especially in oligotrophic environments. Here, we present a non-enzymatic, hybridization chain reaction (HCR)-based signal amplified in situ whole-cell detection technique (in situ DNA-HCR). The components of the amplification buffer were optimized to polymerize DNA amplifier probes for in situ DNA-HCR. In situ hybridization of initiator probes followed by signal amplification via HCR produced bright signals with high specificity and probe permeation into cells. The detection rates for Bacteria in a seawater sample and Archaea in anaerobic sludge samples were comparable with or greater than those obtained by catalyzed reporter deposition (CARD)-FISH or standard FISH. Detection of multiple organisms (Bacteria, Archaea and Methanosaetaceae) in an anaerobic sludge sample was achieved by simultaneous in situ DNA-HCR. In summary, in situ DNA-HCR is a simple and easy technique for detecting single microbial cells and enhancing understanding of the ecology and behaviour of environmental microorganisms in situ. PMID:25523128

  13. Fast and stable redox reactions of MnO2/CNT hybrid electrodes for dynamically stretchable pseudocapacitors.

    PubMed

    Gu, Taoli; Wei, Bingqing

    2015-07-21

    Pseudocapacitors, which are energy storage devices that take advantage of redox reactions to store electricity, have a different charge storage mechanism compared to lithium-ion batteries (LIBs) and electric double-layer capacitors (EDLCs), and they could realize further gains if they were used as stretchable power sources. The realization of dynamically stretchable pseudocapacitors and understanding of the underlying fundamentals of their mechanical-electrochemical relationship have become indispensable. We report herein the electrochemical performance of dynamically stretchable pseudocapacitors using buckled MnO2/CNT hybrid electrodes. The extremely small relaxation time constant of less than 0.15 s indicates a fast redox reaction at the MnO2/CNT hybrid electrodes, securing a stable electrochemical performance for the dynamically stretchable pseudocapacitors. This finding and the fundamental understanding gained from the pseudo-capacitive behavior coupled with mechanical deformation under a dynamic stretching mode would provide guidance to further improve their overall performance including a higher power density than LIBs, a higher energy density than EDLCs, and a long-life cycling stability. Most importantly, these results will potentially accelerate the applications of stretchable pseudocapacitors for flexible and biomedical electronics. PMID:26090617

  14. Addition reactions of thiophenol to ?,?-unsaturated carbonyl compounds using organic acid radical basic anion-exchange resins as catalysts

    Microsoft Academic Search

    Mingxia Li; Jinxia Huang; Wanxuan Zhang

    2001-01-01

    A series of organic acid radical basic anion-exchange resins were prepared from strongly basic quarternary ammonium I type anion-exchange resins, using as the catalysts in addition reactions of thiophenol to ?,?-unsaturated carbonyl compounds. The catalytic activity are influenced by exchange capacity, reaction temperature, solvent and molecular structure.

  15. Effects of free fatty acids, water content and co-solvent on biodiesel production by supercritical methanol reaction

    Microsoft Academic Search

    Kok Tat Tan; Keat Teong Lee; Abdul Rahman Mohamed

    2010-01-01

    In the present study, non-catalytic supercritical methanol (SCM) reaction was utilized to produce biodiesel from palm oil. The effects of free fatty acids and water content on the yield of biodiesel were investigated and subsequently compared with conventional catalytic reaction. In addition, the feasibility of utilizing co-solvent to reduce the operating conditions needed in SCM was carried out as well.

  16. Synthesis and biological evaluation of hybrids from farnesylthiosalicylic acid and hydroxylcinnamic acid with dual inhibitory activities of Ras-related signaling and phosphorylated NF-?B.

    PubMed

    Ling, Yong; Wang, Zhiqiang; Wang, Xuemin; Zhao, Ying; Zhang, Wei; Wang, Xinyang; Chen, Li; Huang, Zhangjian; Zhang, Yihua

    2014-07-01

    A series of hybrids (5a–r) of farnesylthiosalicylic acid (FTS) and hydroxylcinnamic acid were designed and synthesized. Most of the hybrids displayed potent antiproliferative activity against seven cancer cell lines in vitro, superior to FTS as well as sorafenib. The most potent compound 5f selectively inhibited cancer cells but not non-tumor liver cell proliferation in vitro, and significantly induced SMMC-7721 cell apoptosis. Interestingly, 5f could simultaneously inhibit not only Ras-related signaling but also phosphorylated NF-?B, which may synergetically contribute to the cell growth inhibition and apoptosis induction. Moreover, 5f showed low acute toxicity to mice and significantly inhibited the hepatoma tumor growth. PMID:24848877

  17. Evidence for an anaphylactic reaction-induced gastric acid secretion from the isolated stomach of the mouse

    Microsoft Academic Search

    I. Szelenyi; S. Postius

    1985-01-01

    Underin vitro circumstances, ovalbumin, administered serosally, caused a definite acid secretory response in the isolated whole stomach of sensitized mice. Acid secretion induced by challenge was inhibited by cimetidine or by pretreatment with disodium cromoglycate. It remained, however, unchanged by mepyramine or atropine. It is likely that a local histamine release caused by an anaphylactic reaction of type 1 might

  18. The H[subscript 3]PO[subscript 4] Acid Ionization Reactions: A Capstone Multiconcept Thermodynamics General Chemistry Laboratory Exercise

    ERIC Educational Resources Information Center

    Nyasulu, Frazier; Barlag, Rebecca; Wise, Lindy; McMills, Lauren

    2013-01-01

    The thermodynamic properties of weak acid ionization reactions are determined. The thermodynamic properties are corresponding values of the absolute temperature (T), the weak acid equilibrium constant (K[subscript a]), the enthalpy of ionization (delta[subscript i]H[degrees]), and the entropy of ionization (delta[subscript i]S[degrees]). The…

  19. Dual-frequency oscillations induced by acidity in Belousov-Zhabotinskii reactions with aldosugars as substrates

    NASA Astrophysics Data System (ADS)

    Li, Hexing; Jin, Ronghua; Dai, Weilin; Deng, Jingfa

    1997-08-01

    Depending on the initial concentration of H 2SO 4, two types of dual-frequency oscillations have been observed in Belousov-Zhabotinskii type reactions catalyzed by Mn 2+ with acetone and aldosugars (arabinose, glucose, galactose, lactose or maltose) as coupled substrates in a batch reactor. No such dual-frequency oscillations have been found when a ketosugar like fructose was used instead of an aldosugar as the substrate; or acetone was replaced by N 2 flow. No oscillations were observed when Ce 3+ was used instead of Mn 2+. The reaction products of aldosugars in different oscillating regimes have been analyzed. The dual-frequency oscillatory patterns have been discussed according to the roles of the substrates and their derivatives formed at different acidity.

  20. Dicarboxylic acid anhydride condensation with compounds containing active methylene groups. 4: Some 4-nitrophthalic anhydride condensation reactions

    NASA Technical Reports Server (NTRS)

    Oskaja, V.; Rotberg, J.

    1985-01-01

    By 4-nitrophthalic anhydride condensation with acetoacetate in acetic anhydride and triethylamine solution with subsequent breakdown of the intermediate condensation product, 5-nitroindanedione-1,3 was obtained. A 4-nitrophthalic anhydride with acetic anhydride, according to reaction conditions, may yield two products: in the presence of potassium acetate and at high temperatures 4-(or 5-)-nitro-2-acetylbenzoic acid is formed: in the presence of triethylamine and at room temperature 5-( or 6-)-nitrophthalic acetic acid is isolated. A 4-nitrophthalic anhydride and malonic acid in pyridine solution according to temperature yield either 5-( or 6-)-nitrophthalic acetic acid or 4-(or 5-)-nitro-2-acetylbenzoic acid.

  1. Cationic liposome-hyaluronic acid hybrid nanoparticles for intranasal vaccination with subunit antigens.

    PubMed

    Fan, Yuchen; Sahdev, Preety; Ochyl, Lukasz J; J Akerberg, Jonathan; Moon, James J

    2015-06-28

    Here we report the development of a new cationic liposome-hyaluronic acid (HA) hybrid nanoparticle (NP) system and present our characterization of these NPs as an intranasal vaccine platform using a model antigen and F1-V, a candidate recombinant antigen for Yersinia pestis, the causative agent of plague. Incubation of cationic liposomes composed of DOTAP and DOPE with anionic HA biopolymer led to efficient ionic complexation and formation of homogenous liposome-polymer hybrid NPs, as evidenced by fluorescence resonance energy transfer, dynamic light scattering, and nanoparticle tracking analyses. Incorporation of cationic liposomes with thiolated HA allowed for facile surface decoration of NPs with thiol-PEG, resulting in the formation of DOTAP/HA core-PEG shell nanostructures. These NPs, termed DOTAP-HA NPs, exhibited improved colloidal stability and prolonged antigen release. In addition, cytotoxicity associated with DOTAP liposomes (LC50~0.2mg/ml) was significantly reduced by at least 20-fold with DOTAP-HA NPs (LC50>4mg/ml), as measured with bone marrow derived dendritic cells (BMDCs). Furthermore, NPs co-loaded with ovalbumin (OVA) and a molecular adjuvant, monophosphoryl lipid A (MPLA) promoted BMDC maturation and upregulation of co-stimulatory markers, including CD40, CD86, and MHC-II, and C57BL/6 mice vaccinated with NPs via intranasal route generated robust OVA-specific CD8(+) T cell and antibody responses. Importantly, intranasal vaccination with NPs co-loaded with F1-V and MPLA induced potent humoral immune responses with 11-, 23-, and 15-fold increases in F1-V-specific total IgG, IgG1, and IgG2c titers in immune sera by day 77, respectively, and induced balanced Th1/Th2 humoral immune responses, whereas mice immunized with the equivalent doses of soluble F1-V vaccine failed to achieve sero-conversion. Overall, these results suggest that liposome-polymer hybrid NPs may serve as a promising vaccine delivery platform for intranasal vaccination against Y. pestis and other infectious pathogens. PMID:25869965

  2. Probing folding/unfolding kinetics, reaction mechanism and thermodynamic stability of nucleic acid hairpins

    NASA Astrophysics Data System (ADS)

    Nayak, Rajesh Kumar

    Nucleic acid hairpins play pivotal roles in biological and cellular processes. The functions of the DNA and RNA hairpins depend upon the conformational changes they adopt during the biological process. Therefore, a clear understanding of their conformational dynamics such as folding and unfolding kinetics, reaction mechanism as well as thermodynamic stability is essential to understand their biological functions. This dissertation describes folding kinetics, reaction mechanism and thermodynamic stability of stem-loop nucleic acid hairpins by using rapid-mixing stopped-flow kinetics and other spectroscopic techniques. Firstly, the folding kinetics and reaction mechanism of a five base-paired stem and twenty one polythymidine loop DNA hairpin as a function of varying monovalent counter ion concentrations have been discussed. The important observation of this investigation is that the DNA hairpin folding is not simply a two-state process, and based on our experiments and kinetic modeling, we proposed a three-state reaction mechanism, wherein, the intermediate formation occurs on microsecond time scale and the complete hairpin formation occurs on millisecond time scale. Secondly, the loop length and counter ion dependent thermodynamic stability and folding of DNA hairpins have been described. This investigation provides a detailed understanding of how the stability and folding changes as a function of loop length and counter ion concentrations. The most important conclusion of this part of the investigation is that the thermodynamic stability of tetraloop hairpins depend upon counter ion concentration regimes and we explained the exceptional stability of a tetraloop hairpin in the higher concentration regime, compared to longer loop length hairpins on the basis of base-stacking effect. Finally, the folding and unfolding kinetics of RNA hairpins with identical four base-paired stem but different nucleotide loop sequence is discussed. Here we observed that the RNA hairpin folding and unfolding can be much more complex than previously thought and also RNA hairpin folding process can be different than DNA hairpin folding process.

  3. Reactivity and reaction intermediates for acetic acid adsorbed on CeO2(111)

    SciTech Connect

    Calaza, Florencia [Max Planck Society, Fritz Haber Institute; Chen, Tsung-Liang [ORNL; Mullins, David R [ORNL; Xu, Ye [Louisiana State University; Overbury, Steven {Steve} H [ORNL

    2015-01-01

    Adsorption and reaction of acetic acid on a CeO2(1 1 1) surface was studied by a combination of ultra-highvacuum based methods including temperature desorption spectroscopy (TPD), soft X-ray photoelectronspectroscopy (sXPS), near edge X-ray absorption spectroscopy (NEXAFS) and reflection absorption IRspectroscopy (RAIRS), together with density functional theory (DFT) calculations. TPD shows that thedesorption products are strongly dependent upon the initial oxidation state of the CeO2surface, includingselectivity between acetone and acetaldehyde products. The combination of sXPS and NEXAFS demon-strate that acetate forms upon adsorption at low temperature and is stable to above 500 K, above whichpoint ketene, acetone and acetic acid desorb. DFT and RAIRS show that below 500 K, bridge bondedacetate coexists with a moiety formed by adsorption of an acetate at an oxygen vacancy, formed bywater desorption.

  4. Molybdenum phosphosulfide: an active, acid-stable, earth-abundant catalyst for the hydrogen evolution reaction.

    PubMed

    Kibsgaard, Jakob; Jaramillo, Thomas F

    2014-12-22

    Introducing sulfur into the surface of molybdenum phosphide (MoP) produces a molybdenum phosphosulfide (MoP|S) catalyst with superb activity and stability for the hydrogen evolution reaction (HER) in acidic environments. The MoP|S catalyst reported herein exhibits one of the highest HER activities of any non-noble-metal electrocatalyst investigated in strong acid, while remaining perfectly stable in accelerated durability testing. Whereas mixed-metal alloy catalysts are well-known, MoP|S represents a more uncommon mixed-anion catalyst where synergistic effects between sulfur and phosphorus produce a high-surface-area electrode that is more active than those based on either the pure sulfide or the pure phosphide. The extraordinarily high activity and stability of this catalyst open up avenues to replace platinum in technologies relevant to renewable energies, such as proton exchange membrane (PEM) electrolyzers and solar photoelectrochemical (PEC) water-splitting cells. PMID:25359678

  5. Time-resolved IR observation of a photocatalytic reaction of pivalic acid on platinized titanium dioxide

    NASA Astrophysics Data System (ADS)

    Maeda, Akihiro; Ishibashi, Taka-aki

    2013-06-01

    Photodegradation of pivalic acid [(CH3)3CCOOH] on a Pt/TiO2 photocatalyst was studied by time-resolved IR spectroscopy in the microsecond-to-millisecond time region. A vibrational band due to t-butyl radical species, as a reaction intermediate, was observed at 1456 cm-1 along with decrease of reactant, bridge-adsorbed pivalate, and product formation. The product did not have vibrational bands in the CC double bond stretch region, suggesting that the main product was isobutane instead of isobutene, which was the main product in the photoreaction of pivalate on the rutile TiO2 (1 1 0) single crystal.

  6. Browning inhibition mechanisms by cysteine, ascorbic acid and citric acid, and identifying PPO-catechol-cysteine reaction products.

    PubMed

    Ali, Hussein M; El-Gizawy, Ahmed M; El-Bassiouny, Rawia E I; Saleh, Mahmoud A

    2015-06-01

    The titled compounds were examined as PPO inhibitors and antibrowning agents; their various mechanisms were investigated and discussed. All compounds reduced significantly both the browning process and PPO activity. Browning index gave strong correlation with PPO activity (r(2)?=?0.96, n?=?19) indicating that the browning process is mainly enzymatic. Ascorbic acid could reduce the formed quinone instantly to the original substrate (catechol) at high concentration (>1.5 %) while at lower concentrations acted as competitive inhibitor (KI?=?0.256?±?0.067 mM). Cysteine, at higher concentrations (?1.0 %), reacted with the resulted quinone to give a colorless products while at the low concentrations, cysteine worked as competitive inhibitor (KI?=?1.113?±?0.176 mM). Citric acid acted only as PPO non-competitive inhibitor with KI?=?2.074?±?0.363 mM. The products of PPO-catechole-cysteine reaction could be separation and identification by LC-ESI-MS. Results indicated that the product of the enzymatic oxidation of catechol, quinone, undergoes two successive nucleophilic attacks by cysteine thiol group. Cysteine was condensed with the resulted mono and dithiocatechols to form peptide side chains. PMID:26028748

  7. Effect of fungicides on the reaction of sorghum hybrids to disease in Burleson County, Texas, 2011

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of fungicides to control anthracnose and grain mold on sorghum hybrids was conducted during the 2011 growing season. Three fungicides Headline, Quilt Xcel, and Topguard were used. Fungicides were applied on 30 May to the middle two rows with a CO2 backpack sprayer, at 30 psi in a spray vol...

  8. Sympathetic cooling and reactions in an ion-neutral hybrid trap.

    NASA Astrophysics Data System (ADS)

    Smith, Winthrop; Wells, James; Goodman, Douglas; Sivarajah, Ilamaran; Narducci, Frank

    2013-05-01

    We investigated the sympathetic cooling of Na+ ions by collisions with cold Na atoms in a hybrid trap consisting of a MOT and a linear Paul trap. Since Na+ is a closed shell ion and lacks optically accessible transitions from the ground state, we applied four general non-optical techniques for thermometry in a hybrid trap. Simulations using SIMION 7.0 and also our experimental results suggest that there is a cooling effect, but this effect is modest for large numbers of ions (~104) . When we attempted to use the Na MOT to cool Ca+ ions, there was evidence of a surprisingly large charge exchange rate, to be discussed. We investigated the sympathetic cooling of Na+ ions by collisions with cold Na atoms in a hybrid trap consisting of a MOT and a linear Paul trap. Since Na+ is a closed shell ion and lacks optically accessible transitions from the ground state, we applied four general non-optical techniques for thermometry in a hybrid trap. Simulations using SIMION 7.0 and also our experimental results suggest that there is a cooling effect, but this effect is modest for large numbers of ions (~104) . When we attempted to use the Na MOT to cool Ca+ ions, there was evidence of a surprisingly large charge exchange rate, to be discussed. Supported in part by NSF Grant PHY0855570 and by the University of Connecticut.

  9. Effect of Fungicides on the Reaction of Sorghum Hybrids to Anthracnose in Burleson County, Texas, 2012

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of three fungicides to control grain mold/weathering and anthracnose on two sorghum hybrids NC+7R34 and Warner W851-DR was conducted during the 2012 growing season. Three fungicides Headline, Quilt Xcel, and Topguard were used. On May 26, plots were inoculated by putting 10 Colletotrichum ...

  10. Reaction mechanism reduction and optimisation for modelling aviation fuel oxidation using standard and hybrid genetic algorithms

    Microsoft Academic Search

    Lionel Elliott; Derek B. Ingham; Adrian G. Kyne; Nicolae S. Mera; Mohamed Pourkashanian; Sean Whittaker

    2006-01-01

    This study describes the development of a new binary encoded genetic algorithm for the combinatorial problem of determining a subset of species and their associated reactions that best represent the full starting point reaction mechanism in modelling aviation fuel oxidation. The genetic algorithm has a dual objective in finding a reduced mechanism that best represents aviation fuel oxidation in both

  11. Uptake of HCl and HOCl onto sulfuric acid. Solubilities, diffusivities, and reaction

    SciTech Connect

    Hanson, D.R.; Ravishankara, A.R. (NOAA Aeronomy Lab., Boulder, CO (United States) Univ. of Colorado, Boulder, CO (United States))

    1993-11-25

    The interaction of HOCl and HCl vapors with liquid sulfuric acid surfaces was studied in a flow tube equipped with chemical ionization mass spectrometry detection. Time-dependent uptake of HCl and HOCl was measured. A methodology for deriving the value of the quantity H[radical]D[sub 1], (the product of the Henry's law coefficient and the square root of the liquid-phase diffusion coefficient) is discussed. The partial pressures of HCl over HCl-doped sulfuric acid solutions were also measured to directly determine H for HCl (H[sub HCl]*). Using the measured values of H[sub HCl]* and H[sub HCl]*[radical]D[sub 1], the value of D[sub 1] for HCl in 50 wt % sulfuric acid was extracted. Values for H[sub HOCl] and for the second-order rate coefficient for the reaction between dissolved HOCl and HCl were also obtained. The application of these results to modeling stratospheric heterogeneous processes in sulfuric acid aerosols is discussed. 31 refs., 14 refs., 3 tabs.

  12. Modeling the reactions of 1-naphthylamine and 4-methylaniline with humic acids: Spectroscopic investigations of the covalent linkages

    SciTech Connect

    Ononye, A.I. (Knoxville College, TN (United States). Dept. of Chemistry); Graveel, J.G. (Purdue Univ., West Lafayette, IN (United States). Dept. of Agronomy)

    1994-04-01

    The covalent binding of two aromatic amines, 1-naphthylamine and 4-methylaniline, to substituted quinones in aqueous solutions has been studied as a model for the covalent binding of amines to humic acids. An imine compound was the only type of product identified for the reactions between 1-naphthylamine and selected quinones. Reactions of 4-methylaniline with the same quinones gave a 1,4- addition product in addition to the imine compound, although only the imine produce was formed when the quinone had bulky substituents at the 2- and 6- positions. These results provide additional insight into the reactions of aromatic amines with humic acid quinones.

  13. Graft-vs.-host reactions in reciprocal hybrid mice. I. Dissociation of T-cell activities in the mixed lymphocyte reaction and two graft-vs.-host assays.

    PubMed

    Morse, H C; Harrison, M R; Asofsky, R

    1974-03-01

    Spleen cells from BALB/c and C57BL/6 mice were tested for their reactivity against reciprocal hybrid tissues ((BALB/c x C57BL/6) F(1) and (C57BL/6 x BALB/c) F(1)) in three assay systems: the mixed lymphocyte reaction (MLR); the Simonsen spleen-weight graft-vs.-host (GVH) assay; and a GVH mortality assay. It was shown that both F(1)'s serve as equally effective stimulators of parental cells in the MLR. In the spleen-weight assay, BALB/c and C57BL/6 cells were equally active in a given host, but greater splenomegaly was observed in (BALB/c x C57BL/6) F(1) hosts regardless of the donor strain. By contrast, BALB/c cells were much less lethal than C57BL/6 cells in (BALB/c x C57BL/6) F(1) hosts than in (C57BL/6 x BALB/c) F(1) hosts, and to a lesser degree C57BL/6 cells were less lethal than BALB/c cells in (C57BL/6 x BALB/c) F(1) hosts. The possibility that modifying substances may differentially alter reactivity of parental lymphocytes and that considerations other than genotype determine the outcome of a GVH reaction are discussed in detail. PMID:4149643

  14. Preparation of organic–inorganic hybrid silica monolith with octyl and sulfonic acid groups for capillary electrochromatograhpy and application in determination of theophylline and caffeine in beverage

    Microsoft Academic Search

    Ming-Luan Chen; Ming-Ming Zheng; Yu-Qi Feng

    2010-01-01

    An organic–inorganic hybrid silica monolithic column with octyl and sulfonic acid groups has been prepared by sol–gel technique for capillary electrochromatograhpy. The structure of hybrid monolith was optimized by changing the composition of tetraethoxysilane (TEOS), octyltriethoxysilane (C8-TEOS) and 3-mercaptopropyltrimethoxysilane (MPTMS) in the mixture of precursors. Then, the obtained hybrid monolith was oxidized using hydrogen peroxide (30%, w\\/w) to yield sulfonic

  15. Synthesis and biological evaluation of boswellic acid-NSAID hybrid molecules as anti-inflammatory and anti-arthritic agents.

    PubMed

    Shenvi, Suvarna; Kiran, K R; Kumar, Krishna; Diwakar, Latha; Reddy, G Chandrasekara

    2015-06-15

    Methyl esters of the ?-boswellic acid (BA) and 11-keto-?-boswellic acid (KBA) obtained from Boswellia serrata resin were subjected to Steglich esterification with the different non-steroidal anti-inflammatory drugs (NSAID) viz., ibuprofen, naproxen, diclophenac and indomethacin. The novel hybrids of methyl boswellate (5-8) and that of methyl 11-keto boswellate (9-12) were evaluated for anti-inflammatory activity by carrageenan-induced rat hind paw edema model and anti-arthritic activity by Complete Freund's Adjuvant (CFA) induced arthritis in Wister albino rat. Significant inhibition on carrageenan-induced paw edema has been observed with 5, 6 and 10 where as in CFA induced rats, hybrids 5, 8, 9 and 12 exhibited pronounced antiarthritic activity. Hybrid molecules 5 and 9 have been found to be more effective in inhibiting in-vivo COX-2 than ibuprofen by itself, thus showing the synergistic effect. Hybrid 5 and 9 tested for in-vitro lipoxygenase and cyclooxygenase-2 (LOX/COX-2) inhibitory activity. The studies revealed that both 5 and 9 inhibited COX-2 relatively better than LOX enzyme. PMID:26010018

  16. Reaction of 3',5'-di-O-acetyl-2'-deoxyguansoine with hypobromous acid.

    PubMed

    Suzuki, Toshinori; Nakamura, Asuka; Inukai, Michiyo

    2013-07-01

    Hypobromous acid (HOBr) is formed by eosinophil peroxidase and myeloperoxidase in the presence of H2O2, Cl(-), and Br(-) in the host defense system of humans, protecting against invading bacteria. However, the formed HOBr may cause damage to DNA and its components in the host. When a guanine nucleoside (3',5'-di-O-acetyl-2'-deoxyguansoine) was treated with HOBr at pH 7.4, spiroiminodihydantoin, guanidinohydantoin/iminoallantoin, dehydro-iminoallantoin, diimino-imidazole, amino-imidazolone, and diamino-oxazolone nucleosides were generated in addition to an 8-bromoguanine nucleoside. The major products were spiroiminodihydantoin under neutral conditions and guanidinohydantoin/iminoallantoin under mildly acidic conditions. All the products were formed in the reaction with HOCl in the presence of Br(-). These products were also produced by eosinophil peroxidase or myeloperoxidase in the presence of H2O2, Cl(-), and Br(-). The results suggest that the products other than 8-bromoguanine may also have importance for mutagenesis by the reaction of HOBr with guanine residues in nucleotides and DNA. PMID:23685182

  17. Identification of cDNAs for jasmonic acid-responsive genes in Polygonum minus roots by suppression subtractive hybridization

    Microsoft Academic Search

    Mian Chee Gor; Ismanizan Ismail; Wan Aida Wan Mustapha; Zamri Zainal; Normah Mohd Noor; Roohaida Othman; Zeti Azura Mohamed Hussein

    2011-01-01

    Elicitation, the plant-based biotechnology approach that utilizes the ability of plant roots to absorb and secrete a vast\\u000a variety of bioactive compounds, was studied on Polygonum minus using jasmonic acid (JA) as an elicitor. To understand the overall molecular responses of P. minus roots to JA induction, a subtracted cDNA library was constructed using the suppression subtractive hybridization (SSH) method.

  18. Ethylene glycol-citric acid-silica hybrid organic-inorganic materials obtained by the sol-gel method

    Microsoft Academic Search

    A. Campero; Judith Cardoso; S. Pacheco

    1997-01-01

    The combination of inorganic polymeric networks with organic molecules leads to hybrid materials. Tetraethoxysilane (TEOS)\\u000a was used as the precursor for the inorganic component, covalently bonded to ethylene glycol (EG) and citric acid (CA) molecules,\\u000a whose esterification provides the in situ water for hydrolysis of TEOS. Ethanol was added in various amounts to the TEOS-EG-CA\\u000a mixtures in order to induce

  19. Predicting state of charge of lead-acid batteries for hybrid electric vehicles by extended Kalman filter

    Microsoft Academic Search

    A. Vasebi; S. M. T. Bathaee; M. Partovibakhsh

    2008-01-01

    This paper describes and introduces a new nonlinear predictor and a novel battery model for estimating the state of charge (SoC) of lead-acid batteries for hybrid electric vehicles (HEV). Many problems occur for a traditional SoC indicator, such as offset, drift and long term state divergence, therefore this paper proposes a technique based on the extended Kalman filter (EKF) in

  20. Preparation and characterization of zinc oxide nanoparticles and their sensor applications for electrochemical monitoring of nucleic acid hybridization

    Microsoft Academic Search

    Tugrul Yumak; Filiz Kuralay; Mihrican Muti; Ali Sinag; Arzum Erdem; Serdar Abaci

    2011-01-01

    In this study, ZnO nanoparticles (ZNP) of approximately 30nm in size were synthesized by the hydrothermal method and characterized by X-ray diffraction (XRD), Braun–Emmet–Teller (BET) N2 adsorption analysis and transmission electron microscopy (TEM). ZnO nanoparticles enriched with poly(vinylferrocenium) (PVF+) modified single-use graphite electrodes were then developed for the electrochemical monitoring of nucleic acid hybridization related to the Hepatitis B Virus

  1. Identification of Dekkera bruxellensis (Brettanomyces) from Wine by Fluorescence In Situ Hybridization Using Peptide Nucleic Acid Probes

    Microsoft Academic Search

    HENRIK STENDER; CLETUS KURTZMAN; JENS J. HYLDIG-NIELSEN; D. Sorensen; ADAM BROOMER; KENNETH OLIVEIRA; HEATHER PERRY-O' KEEFE; ANDREW SAGE; BARBARA YOUNG; JAMES COULL

    2001-01-01

    A new fluorescence in situ hybridization method using peptide nucleic acid (PNA) probes for identification of Brettanomyces is described. The test is based on fluorescein-labeled PNA probes targeting a species-specific sequence of the rRNA of Dekkera bruxellensis. The PNA probes were applied to smears of colonies, and results were interpreted by fluorescence microscopy. The results obtained from testing 127 different

  2. In Situ Hybridization of Prochlorococcus and Synechococcus (Marine Cyanobacteria) spp. with rRNA-Targeted Peptide Nucleic Acid Probes

    Microsoft Academic Search

    ALEXANDRA Z. WORDEN; SALLIE W. CHISHOLM; BRIAN J. BINDER

    2000-01-01

    A simple method for whole-cell hybridization using fluorescently labeled rRNA-targeted peptide nucleic acid (PNA) probes was developed for use in marine cyanobacterial picoplankton. In contrast to established protocols, this method is capable of detecting rRNA in Prochlorococcus, the most abundant unicellular marine cyanobacterium. Because the method avoids the use of alcohol fixation, the chlorophyll content of Prochloro- coccus cells is

  3. Fluorescence In Situ Hybridization with Peptide Nucleic Acid Probes for Rapid Identification of Candida albicans Directly from Blood Culture Bottles

    Microsoft Academic Search

    Susan Rigby; Gary W. Procop; Gerhard Haase; Deborah Wilson; Cletus Kurtzman; Kenneth Oliveira; Sabina Von Oy; Jens J. Hyldig-Nielsen; James Coull; Henrik Stender

    2002-01-01

    A new fluorescence in situ hybridization (FISH) method that uses peptide nucleic acid (PNA) probes for identification of Candida albicans directly from positive-blood-culture bottles in which yeast was observed by Gram staining (herein referred to as yeast-positive blood culture bottles) is described. The test (the C. albicans PNA FISH method) is based on a fluorescein-labeled PNA probe that targets C.

  4. Electrochemical detection of hybridization using peptide nucleic acids and methylene blue on self-assembled alkanethiol monolayer modified gold electrodes

    Microsoft Academic Search

    Dilsat Ozkan; Arzum Erdem; Pinar Kara; Kagan Kerman; J Justin Gooding; Peter E Nielsen; Mehmet Ozsoz

    2002-01-01

    An electrochemical hybridization biosensor based on peptide nucleic acid (PNA) probes is presented. PNA probes were attached covalently through a competition of free amines on the guanine bases and also at the 5? end of the probe, using N-(3-dimethylamino)propyl)-N?-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) onto a carboxylate terminated alkanethiol self-assembled monolayer (SAM) preformed on a gold electrode (AuE). The covalently

  5. Rapid Identification of Staphylococcus aureus Directly from Blood Cultures by Fluorescence In Situ Hybridization with Peptide Nucleic Acid Probes

    Microsoft Academic Search

    Kenneth Oliveira; Gary W. Procop; Deborah Wilson; James Coull; Henrik Stender

    2002-01-01

    A new fluorescence in situ hybridization (FISH) method with peptide nucleic acid (PNA) probes for identification of Staphylococcus aureus directly from positive blood culture bottles that contain gram-positive cocci in clusters (GPCC) is described. The test (the S. aureus PNA FISH assay) is based on a fluorescein- labeled PNA probe that targets a species-specific sequence of the 16S rRNA of

  6. Reverse dot blot hybridization: a useful method for the direct identification of lactic acid bacteria in fermented food.

    PubMed

    Ehrmann, M; Ludwig, W; Schleifer, K H

    1994-04-01

    A rapid method for a reliable and simultaneous identification of different lactic acid bacteria in fermented food has been developed. Various 16S and 23S rRNA-targeted, species-specific oligonucleotides were applied as capture probes in a non-radioactive reverse dot blot hybridization. A simple and fast DNA extraction method in combination with in vitro amplification of rRNA gene fragments enables the direct detection of typical starter organisms without any preceding enrichment or cultivation steps. Various lactic acid bacteria occurring in cheese, yogurt, sausages, sauerkraut and sourdough could be identified at the species level within 1 day. PMID:8181717

  7. A hybrid variational-perturbation calculation of the ro-vibrational spectrum of nitric acid.

    PubMed

    Pavlyuchko, A I; Yurchenko, S N; Tennyson, Jonathan

    2015-03-01

    Rotation-vibration spectra of the nitric acid molecule, HNO3, are calculated for wavenumbers up to 7000 cm(-1). Calculations are performed using a Hamiltonian expressed in internal curvilinear vibrational coordinates employing a hybrid variational-perturbation method. An initial potential energy surface (PES) and dipole moment function (DMF) are calculated ab initio at the CCSD(T)/aug-cc-pVQZ level of theory. Parameters of the PES and DMF are varied to minimize differences between the calculated and experimental transition frequencies and intensities. The average, absolute deviation between calculated and experimental values is 0.2 cm(-1) for frequencies in the fundamental bands and 0.4 cm(-1) for those in the first overtone and lowest combination bands. For the intensities, the calculated and experimental values differ by 0.3% and 40% for the fundamentals and overtones, respectively. The optimized PES and DMF are used to calculate the room-temperature ro-vibrational spectrum. These calculation reproduce both the form of the absorption bands and fine details of the observed spectra, including the rotational structure of the vibrational bands and the numerous hot absorption band. Many of these hot bands are found to be missing from the compilation in HITRAN. A room temperature line list comprising 2 × 10(9) lines is computed. PMID:25747083

  8. Hybrid finite element and Brownian dynamics method for diffusion-controlled reactions

    PubMed Central

    Bauler, Patricia; Huber, Gary A.; McCammon, J. Andrew

    2012-01-01

    Diffusion is often the rate determining step in many biological processes. Currently, the two main computational methods for studying diffusion are stochastic methods, such as Brownian dynamics, and continuum methods, such as the finite element method. This paper proposes a new hybrid diffusion method that couples the strengths of each of these two methods. The method is derived for a general multidimensional system, and is presented using a basic test case for 1D linear and radially symmetric diffusion systems. PMID:22559470

  9. Surfactant control of gas transport and reactions at the surface of sulfuric acid.

    PubMed

    Park, Seong-Chan; Burden, Daniel K; Nathanson, Gilbert M

    2009-02-17

    Aerosol particles in the atmosphere are tiny chemical reactors that catalyze numerous reactions, including the conversion of benign gases into ozone-destroying ones. In the lower stratosphere, these particles are often supercooled mixtures of water and sulfuric acid. The different species present at the surface of these droplets (H(2)O, H(3)O(+), HSO(4)(-), H(2)SO(4), and SO(4)(2-)) stand at the "gas-liquid frontier"; as the first to be struck by impinging molecules, these species provide the initial environment for solvation and reaction. Furthermore, aerosol particles may contain a wide range of organic molecules, some of which migrate to the surface and coat the droplet. How do ambient gases dissolve in the droplet if it is coated with an organic layer? At one extreme, monolayer films of insoluble, long-chain alcohols can dramatically reduce gas transport, packing so tightly at the surface of water that they impede water evaporation by factors of 10,000 or more. Shorter chain surfactants are expected to pack less tightly, but we wondered whether these incomplete monolayers also block gas transport and whether this system could serve as a model for understanding the surfaces of atmospheric aerosol particles. To address these questions, our research focuses on small, soluble surfactants such as butanol and hexanol dissolved in supercooled sulfuric acid. These amphiphilic molecules spontaneously segregate to the surface and coat the acid but only to a degree. Gas-liquid scattering experiments reveal that these porous films behave in surprisingly diverse ways: they can impose a barrier (to N(2)O(5) hydrolysis), be "invisible" (to water evaporation), or even enhance gas uptake (of HCl). The transition from obstacle to catalyst can be traced to specific interactions between the surfactant and each gas. For example, the hydrolysis of N(2)O(5) may be impeded because of its large size and because alcohol molecules that straddle the interface limit contact between N(2)O(5) and its H(3)O(+) and H(2)O reaction partners. However, these same alcohol molecules assist HCl dissociation because the alcohol OH groups provide extra interfacial protonation sites. Interestingly, butanol does not impede water evaporation, in part because the butyl chains pack much more loosely than insoluble, long-chain surfactants. Through these investigations, we hope to gain insight into the mechanisms by which surfactants on sulfuric acid and other aqueous solutions affect transport and reactivity at the gas-liquid interface. PMID:19119820

  10. Hybrid binuclear-cobalt-phthalocyanine as oxygen reduction reaction catalyst in single chamber microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Li, Baitao; Zhou, Xiuxiu; Wang, Xiujun; Liu, Bingchuan; Li, Baikun

    2014-12-01

    A novel hybrid binuclear-cobalt-phthalocyanine (Bi-CoPc) is developed as the cathode catalyst to replace the costly platinum (Pt) in single chamber microbial fuel cells (SCMFCs). Bi-CoPc/C is integrated with metal oxides (NiO and CoO) to form macrocyclic complex for enhanced oxygen reduction rate (ORR). The characteristics of hybrid catalysts (Bi-CoPc/C-CoO and Bi-CoPc/C-NiO) are compared with Co-contained catalysts (CoPc/C and Bi-CoPc/C) and metal oxide catalysts (NiO and CoO). The increase in O and N functional groups indicates the benefits of NiO and CoO to the cathode catalysts. The cyclic voltammetry (CV) shows the reduction peak for Bi-CoPc/C-NiO and Bi-CoPc/C-CoO at -0.12 V and -0.22 V, respectively. The power densities (368 mW m-2 and 400 mW m-2) of SCMFCs with Bi-CoPc/C-CoO and Bi-CoPc-NiO/C are the highest among the cathodes tested, and close to that of Pt (450 mW m-2). This study demonstrates that hybrid Bi-CoPc/C with metal oxides has a great potential as a cost-effective catalyst in MFCs.

  11. Reaction Kinetics for the Biocatalytic Conversion of Phenazine-1-Carboxylic Acid to 2-Hydroxyphenazine

    PubMed Central

    Chen, Mingmin; Cao, Hongxia; Peng, Huasong; Hu, Hongbo; Wang, Wei; Zhang, Xuehong

    2014-01-01

    The phenazine derivative 2-hydroxyphenazine (2-OH-PHZ) plays an important role in the biocontrol of plant diseases, and exhibits stronger bacteriostatic and fungistatic activity than phenazine-1-carboxylic acid (PCA) toward some pathogens. PhzO has been shown to be responsible for the conversion of PCA to 2-OH-PHZ, however the kinetics of the reaction have not been systematically studied. Further, the yield of 2-OH-PHZ in fermentation culture is quite low and enhancement in our understanding of the reaction kinetics may contribute to improvements in large-scale, high-yield production of 2-OH-PHZ for biological control and other applications. In this study we confirmed previous reports that free PCA is converted to 2-hydroxy-phenazine-1-carboxylic acid (2-OH-PCA) by the action of a single enzyme PhzO, and particularly demonstrate that this reaction is dependent on NADP(H) and Fe3+. Fe3+ enhanced the conversion from PCA to 2-OH-PHZ and 28°C was a optimum temperature for the conversion. However, PCA added in excess to the culture inhibited the production of 2-OH-PHZ. 2-OH-PCA was extracted and purified from the broth, and it was confirmed that the decarboxylation of 2-OH-PCA could occur without the involvement of any enzyme. A kinetic analysis of the conversion of 2-OH-PCA to 2-OH-PHZ in the absence of enzyme and under different temperatures and pHs in vitro, revealed that the conversion followed first-order reaction kinetics. In the fermentation, the concentration of 2-OH-PCA increased to about 90 mg/L within a red precipitate fraction, as compared to 37 mg/L within the supernatant. The results of this study elucidate the reaction kinetics involved in the biosynthesis of 2-OH-PHZ and provide insights into in vitro methods to enhance yields of 2-OH-PHZ. PMID:24905009

  12. In vivo assessment of effect of phytotoxin tenuazonic acid on PSII reaction centers.

    PubMed

    Chen, Shiguo; Strasser, Reto Jörg; Qiang, Sheng

    2014-11-01

    Tenuazonic acid (TeA), a phytotoxin produced by the fungus Alternaria alternata isolated from diseased croftonweed (Ageratina adenophora), exhibits a strong inhibition in photosystem II (PSII) activity. In vivo chlorophyll fluorescence transients of the host plant croftonweed, show that the dominant effect of TeA is not on the primary photochemical reaction but on the biochemical reaction after QA. The most important action site of TeA is the QB site on the PSII electron-acceptor side, blocking electron transport beyond QA(-) by occupying the QB site in the D1 protein. However, TeA does not affect the antenna pigments, the energy transfer from antenna pigment molecules to reaction centers (RCs), and the oxygen-evolving complex (OEC) at the donor side of PSII. TeA severely inactivated PSII RCs. The fraction of non-QA reducing centers and non-QB reducing centers show a time- and concentration-dependent linear increase. Conversely, the amount of active QA or QB reducing centers declined sharply in a linear way. The fraction of non-QB reducing centers calculated from data of fluorescence transients is close to the number of PSII RCs with their QB site filled by TeA. An increase of the step-J level (VJ) in the OJIP fluorescence transients attributed to QA(-) accumulation due to TeA bound to the QB site is a typical characteristic response of the plants leaf with respect to TeA penetration. PMID:25240106

  13. Determination of acidity and nucleophilicity in thiols by reaction with monobromobimane and fluorescence detection.

    PubMed

    Sardi, Florencia; Manta, Bruno; Portillo-Ledesma, Stephanie; Knoops, Bernard; Comini, Marcelo A; Ferrer-Sueta, Gerardo

    2013-04-01

    A method based on the differential reactivity of thiol and thiolate with monobromobimane (mBBr) has been developed to measure nucleophilicity and acidity of protein and low-molecular-weight thiols. Nucleophilicity of the thiolate is measured as the pH-independent second-order rate constant of its reaction with mBBr. The ionization constants of the thiols are obtained through the pH dependence of either second-order rate constant or initial rate of reaction. For readily available thiols, the apparent second-order rate constant is measured at different pHs and then plotted and fitted to an appropriate pH function describing the observed number of ionization equilibria. For less available thiols, such as protein thiols, the initial rate of reaction is determined in a wide range of pHs and fitted to the appropriate pH function. The method presented here shows excellent sensitivity, allowing the use of nanomolar concentrations of reagents. The method is suitable for scaling and high-throughput screening. Example determinations of nucleophilicity and pK(a) are presented for captopril and cysteine as low-molecular-weight thiols and for human peroxiredoxin 5 and Trypanosoma brucei monothiol glutaredoxin 1 as protein thiols. PMID:23296042

  14. Using stretching and bending vibrations to direct the reaction of Cl atoms with isocyanic acid (HNCO)

    NASA Astrophysics Data System (ADS)

    Woods, Ephraim; Cheatum, Christopher M.; Crim, F. Fleming

    1999-10-01

    Reaction of well-characterized vibrational states prepared in the region of three quanta of N-H stretching excitation explores how vibrations with different components along the reaction coordinate influence the bimolecular reaction of Cl atoms with isocyanic acid (HNCO) to form HCl and NCO. Near prolate symmetric top states corresponding to different amounts of a-axis rotation are well separated in energy, and perturbations by background states make each of the eigenstates a different mixture of zero-order states. Molecules in the essentially unperturbed K=1 and 4 states, which are nearly pure N-H stretching excitation, react efficiently, but those in the perturbed states, K=0, 2, and 3, which are a mixture of N-H stretching and lower frequency vibrations react only half as well. Detailed analysis of resolved, perturbed eigenstates for J=6 and 7 of K=3 reveals the relative reactivity of the two interacting zero-order states. The less reactive zero-order state, which most likely contains only two quanta of N-H stretch and several quanta of other vibrations, reacts only 10% as well as the pure N-H stretch zero-order state. Ab initio calculations suggest that bending excitation alters the interaction potential to reduce the fraction of reactive collisions.

  15. Sensitive detection of a serum biomarker based on peptide nucleic acid-coupled dual cycling reactions.

    PubMed

    Zhang, Yuanyuan; Li, Hao; Huang, Yue; Yin, Tingting; Sun, Lizhou; Li, Genxi

    2015-07-01

    Serum level of disease markers may provide important guidance for diagnosis and prognosis. In this work, a sensitive and specific method suitable for direct serum detection of biomarkers is developed based on peptide nucleic acid (PNA)-coupled DNA cycling reactions with dual amplification. In this method, PNA released from a target-triggered homogeneous DNA cycling is employed to initiate an interface DNA cycling, and both of the cycling reactions are based on polymerase-assisted strand displacement reaction. Consequently, two PNA-coupled DNA cycling steps can take place simultaneously in one-pot, leading to greatly enhanced limit of detection and simplified operation. This method has also been successfully applied for evaluating serum insulin in pregnant women as an indicator of gestational diabetes mellitus. So the application of this method in real bio-samples may allow it to hold considerable potential in clinical practice. In addition, since there is no requirement for specific sequence of aptamer, the strategy proposed can be extended for the detection of many other protein markers and peptide-hormones in the future. PMID:26043088

  16. Synthesis and characterization of Pd-poly(N-vinyl-2-pyrrolidone)/KIT-5 nanocomposite as a polymer-inorganic hybrid catalyst for the Suzuki-Miyaura cross-coupling reaction

    SciTech Connect

    Kalbasi, Roozbeh Javad, E-mail: rkalbasi@iaush.ac.ir [Department of Chemistry, Shahreza Branch, Islamic Azad University, 311-86145 Shahreza, Isfahan (Iran, Islamic Republic of); Mosaddegh, Neda [Department of Chemistry, Shahreza Branch, Islamic Azad University, 311-86145 Shahreza, Isfahan (Iran, Islamic Republic of)

    2011-11-15

    Composite poly(N-vinyl-2-pyrrolidone)/KIT-5 (PVP/KIT-5) was prepared by in situ polymerization method and used as a support for palladium nanoparticles obtained through the reduction of Pd(OAc){sub 2} by hydrazine hydrate. The physical and chemical properties of the catalyst were investigated by XRD, FT-IR, UV-vis, TG, BET, SEM, and TEM techniques. The catalytic performance of this novel heterogeneous catalyst was determined for the Suzuki-Miyaura cross-coupling reaction between aryl halides and phenylboronic acid in the presence of water at room temperature. The stability of the nanocomposite catalyst was excellent and could be reused 8 times without much loss of activity in the Suzuki-Miyaura cross-coupling reaction. - Graphical Abstract: Pd-poly(N-vinyl-2-pyrrolidone)/KIT-5 was prepared as an organic-inorganic hybrid catalyst for the Suzuki-Miyaura reaction. The stability of the catalyst was excellent and could be reused 8 times in the Suzuki-Miyaura reaction. Highlights: > Pd-poly(N-vinyl-2-pyrrolidone)/KIT-5 was prepared as a novel nanocomposite. > Nanocomposite was prepared based on a cage-type mesoporous system. > Catalyst showed excellent activity for Suzuki-Miyaura reaction in water. > Stability of the catalyst was excellent and could be reused 8 times.

  17. Kinetics of Photoresponse of the Chlorine Dioxide-Iodine-Malonic Acid Reaction Attila K. Horvath, Milos Dolnik, Anatol M. Zhabotinsky,* and Irving R. Epstein

    E-print Network

    Epstein, Irving R.

    Kinetics of Photoresponse of the Chlorine Dioxide-Iodine-Malonic Acid Reaction Attila K. Horva; In Final Form: March 28, 2000 We studied the photoresponse of the chlorine dioxide-iodine-malonic acid it was shown4,5 that the core reaction in this system is actually the chlorine dioxide-iodine-malonic acid

  18. Synthesis of pyrazole containing ?-amino acids via a highly regioselective condensation/aza-Michael reaction of ?-aryl ?,?-unsaturated ketones.

    PubMed

    Gilfillan, Lynne; Artschwager, Raik; Harkiss, Alexander H; Liskamp, Rob M J; Sutherland, Andrew

    2015-04-21

    A synthetic approach for the preparation of a new class of highly conjugated unnatural ?-amino acids bearing a 5-arylpyrazole side-chain has been developed. Horner-Wadsworth-Emmons reaction of an aspartic acid derived ?-keto phosphonate ester with a range of aromatic aldehydes gave ?-aryl ?,?-unsaturated ketones. Treatment of these with phenyl hydrazine followed by oxidation allowed the regioselective synthesis of pyrazole derived ?-amino acids. As well as evaluating the fluorescent properties of the ?-amino acids, their synthetic utility was also explored with the preparation of a sulfonyl fluoride derivative, a potential probe for serine proteases. PMID:25774874

  19. Quantitative study of solid-state acid–base reactions between polymorphs of flufenamic acid and magnesium oxide using X-ray powder diffraction

    Microsoft Academic Search

    Xiaoming Chen; Joseph G. Stowell; Kenneth R. Morris; Stephen R. Byrn

    2010-01-01

    The purpose of this study is to investigate solid-state acid–base reactions between polymorphs of flufenamic acid (FFA) and magnesium oxide (MgO) using X-ray powder diffraction (XRPD). Polymorphs of FFA were blended with MgO and stored under conditions of 96.5% RH and 89% RH at 40°C. The disappearance of FFA and production of magnesium flufenamate were monitored by XRPD. It was

  20. Kinetic Studies on the Reaction of Sulfinic Acids with Conjugated Alkenes: IV. Kinetics of the Addition of Arenesulfinic Acids to 2-nitro-1-phenyl-1-phenylsulfonylethene

    Microsoft Academic Search

    S. Ivanova; D. I. Aleksiev

    2002-01-01

    The addition of unsubstituted and substituted benzenesulfinic acids to 2-nitro-1-phenyl-1-phenylsulfonylethene was studied kinetically by means of LC. The reaction follows the second-order kinetics: v = k[2-nitro-1-phenyl-1-phenylsulfonylethene] ·; [sulfinic acid]. The dependance of the rate constants on the temperature, and the influence of the p-substituents on the kinetic parameters were studied. The activation energy and the enthalpy of activation were calculated

  1. Identification of Aeromonas trota (hybridization group 13) by amplification of the aerolysin gene using polymerase chain reaction.

    PubMed

    Khan, A A; Nawaz, M S; Khan, S A; Cerniglia, C E

    1999-04-01

    Aeromonas trota is recognized as an important enteropathogen, and its haemolysin (aerolysin) is purported to be one of the virulence factors. Rapid detection and identification of A. trota is important for early and specific diagnosis of the infectious diseases that it causes. Synthetic oligonucleotide primers were used in a polymerase chain reaction (PCR) technique to amplify a species-specific sequence of the aerA gene, which encodes the aerolysin of A. trota. A DNA fragment of 622 bp was amplified from both lysed cells and isolated DNA from A. trota. The identity of the amplified 622 bp fragment was confirmed by digestion with BamH I restriction endonuclease, which produced the predicted 557 and 65 bp fragments. The lower limit for detection of the aerA gene by PCR amplification was 10 pg of total DNA or 10-15 cells ml-1. Primer specificity for A. trota was determined by the PCR assay with cells of 55 strains of Aeromonas sppincluding all of the 14 currently recognized DNA hybridization groups. A strain of Aeromonas enteropelogenes that had been reclassified as A. trota was also PCR positive. The method described here can be used to detect aerolysin-producing A. trota (hybridization group 13) strains from environmental and clinical samples without the use of selective media or additional biochemical tests. PMID:10208799

  2. Detection of Food Spoilage and Pathogenic Bacteria Based on Ligation Detection Reaction Coupled to Flow-Through Hybridization on Membranes

    PubMed Central

    Böhme, K.; Cremonesi, P.; Severgnini, M.; Villa, Tomás G.; Fernández-No, I. C.; Barros-Velázquez, J.; Castiglioni, B.; Calo-Mata, P.

    2014-01-01

    Traditional culturing methods are still commonly applied for bacterial identification in the food control sector, despite being time and labor intensive. Microarray technologies represent an interesting alternative. However, they require higher costs and technical expertise, making them still inappropriate for microbial routine analysis. The present study describes the development of an efficient method for bacterial identification based on flow-through reverse dot-blot (FT-RDB) hybridization on membranes, coupled to the high specific ligation detection reaction (LDR). First, the methodology was optimized by testing different types of ligase enzymes, labeling, and membranes. Furthermore, specific oligonucleotide probes were designed based on the 16S rRNA gene, using the bioinformatic tool Oligonucleotide Retrieving for Molecular Applications (ORMA). Four probes were selected and synthesized, being specific for Aeromonas spp., Pseudomonas spp., Shewanella spp., and Morganella morganii, respectively. For the validation of the probes, 16 reference strains from type culture collections were tested by LDR and FT-RDB hybridization using universal arrays spotted onto membranes. In conclusion, the described methodology could be applied for the rapid, accurate, and cost-effective identification of bacterial species, exhibiting special relevance in food safety and quality. PMID:24818128

  3. Fast DNA hybridization chip using denature and motion of nucleic acids

    Microsoft Academic Search

    Yung-Chiang Chung; Yu-Cheng Lin; Chaung-Di Chueh; Chuan-You Ye; Li-Wei Lai; Wei-Chieh Liao

    2010-01-01

    We demonstrate that the efficiency of DNA hybridization could be improved by introducing elevated temperature in the hot region and higher velocities in the cold region of a microfluidic chip. Compared with the conventional methods, this hybridization microchip was shown to increase the hybridization signal 4.6-fold within 30 minutes using a 1.4 kb target DNA as the test material. The

  4. Fast DNA hybridization chip by controling temperature and velocity of nucleic acids

    Microsoft Academic Search

    Yung-Chiang Chung; Yu-Cheng Lin; Wei-Chieh Liao; Po-Wen Chen; Fong-Jian Sie; Chia-Ming Hu

    2009-01-01

    We demonstrate that the efficiency of DNA hybridization could be improved by introducing elevated temperature in the hot region and higher velocities in the cold region of a microfluidic chip. Compared with the conventional methods, this hybridization microchip was shown to increase the hybridization signal 4.6-fold within 30 minutes using a 1.4 kb target DNA as the test material. The

  5. The kinetics of formation of horseradish peroxidase compound I by reaction with peroxobenzoic acids. pH and peroxo acid substituent effects.

    PubMed Central

    Davies, D M; Jones, P; Mantle, D

    1976-01-01

    1. The kinetics of formation of horseradish peroxidase Compound I were studied by using peroxobenzoic acid and ten substituted peroxobenzoic acids as substrates. Kinetic data for the formation of Compound I with H2O2 and for the reaction of deuteroferrihaem with H2O2 and peroxobenzoic acids, to form a peroxidatically active intermediate, are included for comparison. 2. The observed second-order rate constants for the formation of Compound I with peroxobenzoic acids decrease with increasing pH, in the range pH 5-10, in contrast with pH-independence of the reaction with H2O2. The results imply that the formation of Compound I involves a reaction between the enzyme and un-ionized hydroperoxide molecules. 3. The maximal rate constants for Compound I formation with unhindered peroxobenzoic acids exceed that for H2O2. Peroxobenzoic acids with bulky ortho substituents show marked adverse steric effects. The pattern of substituent effects does not agree with expectations for an electrophilic oxidation of the enzyme by peroxoacid molecules in aqueous solution, but is in agreement with that expected for a reaction involving nucleophilic attack by peroxo anions. 4. Possible reaction mechanisms are considered by which the apparent conflict between the pH-effect and substituent-effect data may be resolved. A model in which it is postulated that a negatively charged 'electrostatic gate' controls access of substrate to the active site and may also activate substrate within the active site, provides the most satisfactory explanation for both the present results and data from the literature. PMID:9067

  6. Hybrid pathwise sensitivity methods for discrete stochastic models of chemical reaction systems.

    PubMed

    Wolf, Elizabeth Skubak; Anderson, David F

    2015-01-21

    Stochastic models are often used to help understand the behavior of intracellular biochemical processes. The most common such models are continuous time Markov chains (CTMCs). Parametric sensitivities, which are derivatives of expectations of model output quantities with respect to model parameters, are useful in this setting for a variety of applications. In this paper, we introduce a class of hybrid pathwise differentiation methods for the numerical estimation of parametric sensitivities. The new hybrid methods combine elements from the three main classes of procedures for sensitivity estimation and have a number of desirable qualities. First, the new methods are unbiased for a broad class of problems. Second, the methods are applicable to nearly any physically relevant biochemical CTMC model. Third, and as we demonstrate on several numerical examples, the new methods are quite efficient, particularly if one wishes to estimate the full gradient of parametric sensitivities. The methods are rather intuitive and utilize the multilevel Monte Carlo philosophy of splitting an expectation into separate parts and handling each in an efficient manner. PMID:25612685

  7. Convenient procedure for the syntheses of vinyl iodides via the reaction of iodine monochloride with vinylboronic acids

    SciTech Connect

    Kabalka, G. W.; Gooch, E. E.; Hsu, H. C.

    1980-01-01

    Vinyl halides are important synthetic intermediates. One route to vinyl halides involves the reaction of vinylboronic acids with halogens in the presence of sodium hydroxide. Although the reaction of iodine with organoborane reagents has been carefully investigated and is known to produce good yields of stereochemically defined products, it does have two potential disadvantages. The first is the necessity of using a strong base which could react with sensitive functional groups. The second is the fact that one-half of the iodine molecule is lost as iodide which is not economical when radionuclides of iodine are employed. An alternative method of preparing vinyl halides is reported in this paper. Vinyl boronic acids (readily prepared via the hydroboration of alkynes) react with iodine monochloride to yield the corresponding vinyl iodides. This reaction is applicable to a variety of functionally substituted materials. The reaction of triphenylborane with iodine monochloride is also reported.

  8. Kinetic analysis of chemical reactions coupled to an enzymic step. Application to acid phosphatase assay with Fast Red.

    PubMed Central

    Escribano, J; García-Carmona, F; García-Cánovas, F; Iborra, J L; Lozano, J A

    1984-01-01

    Acid phosphatase assay with alpha-naphthyl phosphate as substrate and the use of diazonium salt (Fast Red TR) for chromophore formation was kinetically analysed as a system of two chemical reactions coupled to an enzymic reaction. This system follows a mechanism defined as enzymic-chemical-chemical (EzCC). The accumulation of chromophore with reaction time presented a marked lag period, which was only dependent on the rate constants of the chemical reactions and was independent of the enzymic step. The specific rate constants of each chemical step were determined in 3.8-5.0 pH and 10-35 degrees C temperature ranges. Thermodynamic parameters of the chemical steps were also obtained. Measurement of acid phosphatase activity can be carried out in the pH range 3.8-5.0 (4.8 was optimal pH) without the need to eliminate the lag period. PMID:6508735

  9. Using dual-polarization interferometry to study surface-initiated DNA hybridization chain reactions in real time.

    PubMed

    Huang, Fujian; Xu, Pingping; Liang, Haojun

    2014-01-15

    In this study we used dual-polarization interferometry to investigate DNA hybridization chain reactions (HCRs) at solid-liquid interfaces. We monitored the effects of variations in mass, thickness, and density of the immobilized initiator on the subsequent HCRs at various salt concentrations. At low salt concentrations, the single-stranded DNA (ssDNA) initiator was attached uniformly to the chip surface. At high salt concentrations, it lay on the surface at the onset of the immobilization process, but the approaching ssDNA forced the pre-immobilized ssDNA strands to extend into solution as a result of increased electrostatic repulsion between the pre-adsorbed and approaching ssDNA chains. Injection of a mixture of H1 and H2 increased the mass and thickness of the films initially, but thereafter the thickness decreased. These changes indicate that the long double-stranded DNA that formed lay on the surface, rather than extended into the solution, thereby suppressing the subsequent initiation activity of the released single-strand parts of H1 and H2. Increasing the salt concentration increased the HCR efficiency and reaction rate. The HCR efficiency of the initiator ssDNA immobilized on its 5' end was higher than that immobilized on its 3' end, suggesting that the released single-strand parts of H1 and H2 close to the chip surface decreased the initiation activity relative to those of the ones extending into solution. PMID:23988858

  10. Nanosilver-based surface-enhanced Raman spectroscopic determination of DNA methyltransferase activity through real-time hybridization chain reaction.

    PubMed

    Hu, Ping Ping; Liu, Hui; Zhen, Shu Jun; Li, Chun Mei; Huang, Cheng Zhi

    2015-11-15

    In this manuscript, a nanosilver enhanced SERS strategy was successfully constructed for the determination of DNA methyltransferase activity in soulution combined with hybridization chain reaction (HCR). The proposed method was mainly on the basis of excellent separation ability of magnetic microparticles (MMPs), HCR as signal amplification unit and assembled AgNPs as enhancement substrate. In the presence of M. SssI MTase, the duplex sequence (5'-CCGG-3') tethered to MMPs was methylated, which cannot be cleaved by HpaII endonuclease. The resulted DNA skeleton captured on MMPs then triggered the HCR reaction, generated a polymerized and extended symmetrical sequence, in which more biotin terminal was available for the conjugation of AgNPs-SA, leading to significantly amplified SERS response. When it was used to analyze M. SssI activity, a linear equation ?ISERS=1215.32+446.80 cM.SssI was obtained with the M. SssI activity ranged from 0.1 to 10.0U with the correlation coefficient (r(2)) of 0.97. The most important advantage of this method is the combination of SERS and HCR in solution for the first time and its good selectivity, which enabled the detection of even one-base mismatched sequence. The new assay method holds great promising application to be a versatile platform for sensitive, high-throughput detection, and the screening of new anticancer drugs on DNA MTase. PMID:26086442

  11. Samarium iodide-mediated Reformatsky reactions for the stereoselective preparation of ?-hydroxy-?-amino acids: synthesis of isostatine and dolaisoleucine.

    PubMed

    Nelson, Christopher G; Burke, Terrence R

    2012-01-01

    The synthesis of ?-hydroxy-?-amino acids via SmI(2)-mediated Reformatsky reactions of ?-chloroacetyloxazolidinones with aminoaldehydes is reported. Diastereoselective coupling is demonstrated to depend on the absolute configuration of the Evans chiral auxiliary employed in the reaction, allowing erythro or threo products to be obtained selectively. The potential utility of the methodology is exemplified by the facile synthesis of biologically relevant N-Boc-isostatine (2b) and N-Boc-dolaisoleucine (3c). PMID:22136325

  12. The new esterification catalysts and the nature of reactions proceeding at esterification of synthetic naphthenic acids in their presence

    Microsoft Academic Search

    A. H. Azizov; G. I. Amanullayeva; R. V. Aliyeva; B. M. Aliyev; N. R. Bektashi

    2011-01-01

    There have been synthesized the novel sulfocationites on the basis of graft copolymers of polystyrene with oligostyrene, and their metal-polymer composites based on the titanium-containing compound with the grafted ionic-liquid type ligands. Esterifacation reaction of synthetic naphthen acid (SNA) fraction with heptyl alcohol as a model reaction has been investigated in the presence of the novel sulfocationites and Ti-containing metal-polymer

  13. Interactions of Hypochlorous Acid with Pyrimidine Nucleotides, and Secondary Reactions of Chlorinated Pyrimidines with GSH, NADH, and Other Substrates

    Microsoft Academic Search

    W. A. Prütz

    1998-01-01

    HOCl-induced chlorination of pyrimidine nucleotides, PyNH, strikingly depends on the nature of the available chlorine acceptor group. For CMP, with an ?NH2group as acceptor, the reaction is slow and involves predominantly the acid [k(CMP + HOCl) ? 100 M?1s?1at pH 6]; apparent rate constants of the reaction decrease around the pKa(HOCl), to 0 in alkaline solution. For TMP and UMP,

  14. Nucleic acid sandwich hybridization assay with quantum dot-induced fluorescence resonance energy transfer for pathogen detection.

    PubMed

    Chou, Cheng-Chung; Huang, Yi-Han

    2012-01-01

    This paper reports a nucleic acid sandwich hybridization assay with a quantum dot (QD)-induced fluorescence resonance energy transfer (FRET) reporter system. Two label-free hemagglutinin H5 sequences (60-mer DNA and 630-nt cDNA fragment) of avian influenza viruses were used as the targets in this work. Two oligonucleotides (16 mers and 18 mers) that specifically recognize two separate but neighboring regions of the H5 sequences were served as the capturing and reporter probes, respectively. The capturing probe was conjugated to QD655 (donor) in a molar ratio of 10:1 (probe-to-QD), and the reporter probe was labeled with Alexa Fluor 660 dye (acceptor) during synthesis. The sandwich hybridization assay was done in a 20 ?L transparent, adhesive frame-confined microchamber on a disposable, temperature-adjustable indium tin oxide (ITO) glass slide. The FRET signal in response to the sandwich hybridization was monitored by a homemade optical sensor comprising a single 400 nm UV light-emitting diode (LED), optical fibers, and a miniature 16-bit spectrophotometer. The target with a concentration ranging from 0.5 nM to 1 ?M was successfully correlated with both QD emission decrease at 653 nm and dye emission increase at 690 nm. To sum up, this work is beneficial for developing a portable QD-based nucleic acid sensor for on-site pathogen detection. PMID:23211753

  15. Light-induced nitrous acid (HONO) production from NO2 heterogeneous reactions on household chemicals

    NASA Astrophysics Data System (ADS)

    Gómez Alvarez, Elena; Sörgel, Matthias; Gligorovski, Sasho; Bassil, Sabina; Bartolomei, Vincent; Coulomb, Bruno; Zetzsch, Cornelius; Wortham, Henri

    2014-10-01

    Nitrous acid (HONO) can be generated in various indoor environments directly during combustion processes or indirectly via heterogeneous NO2 reactions with water adsorbed layers on diverse surfaces. Indoors not only the concentrations of NO2 are higher but the surface to volume (S/V) ratios are larger and therefore the potential of HONO production is significantly elevated compared to outdoors. It has been claimed that the UV solar light is largely attenuated indoors. Here, we show that solar light (? > 340 nm) penetrates indoors and can influence the heterogeneous reactions of gas-phase NO2 with various household surfaces. The NO2 to HONO conversion mediated by light on surfaces covered with domestic chemicals has been determined at atmospherically relevant conditions i.e. 50 ppb NO2 and 50% RH. The formation rates of HONO were enhanced in presence of light for all the studied surfaces and are determined in the following order: 1.3·109 molecules cm-2 s-1 for borosilicate glass, 1.7·109 molecules cm-2 s-1 for bathroom cleaner, 1.0·1010 molecules cm-2 s-1 on alkaline detergent (floor cleaner), 1.3·1010 molecules cm-2 s-1 for white wall paint and 2.7·1010 molecules cm-2 s-1 for lacquer. These results highlight the potential of household chemicals, used for cleaning purposes to generate HONO indoors through light-enhanced NO2 heterogeneous reactions. The results obtained have been applied to predict the timely evolution of HONO in a real indoor environment using a dynamic mass balance model. A steady state mixing ratio of HONO has been estimated at 1.6 ppb assuming a contribution from glass, paint and lacquer and considering the photolysis of HONO as the most important loss process.

  16. Photochemical reactions of divalent mercury with thioglycolic acid: formation of mercuric sulfide particles.

    PubMed

    Si, Lin; Ariya, Parisa A

    2015-01-01

    Mercury (Hg) is a key toxic global pollutant. Studies in aquatic environment have suggested that thiols could be important for mercury speciation. Thioglycolic acid has been detected in various natural water systems and used as a model compound to study the complicated interaction between mercury and polyfunctional dissolved organic matter (DOM). We herein presented the first evidence for mercury particle formation during kinetic and product studies on the photochemistry of divalent mercury (Hg(2+)) with thioglycolic acid at near environmental conditions. Mercuric sulfide (HgS) particles formed upon photolysis were identified by high-resolution transmission electron microscopy coupled with energy dispersive spectrometry and select area electron diffraction. Kinetic data were obtained using UV-visible spectrophotometry and cold vapour atomic fluorescent spectrometry. The apparent first-order reaction rate constant under our experimental conditions was calculated to be (2.3±0.4)×10(-5) s(-1) at T=296±2 K and pH 4.0. It was found that (89±3)% of the reactants undergo photoreduction to generate elemental mercury (Hg(0)). The effects of ionic strengths, pH and potassium ion were also investigated. The formation of HgS particles pointed to the possible involvement of heterogeneous processes. Our kinetic results indicated the importance of weak binding sites on DOM to Hg in photoreduction of Hg(2+) to Hg(0). The potential implications of our data on environmental mercury transformation were discussed. PMID:25094064

  17. A general reaction-diffusion model of acidity in cancer invasion.

    PubMed

    McGillen, Jessica B; Gaffney, Eamonn A; Martin, Natasha K; Maini, Philip K

    2014-04-01

    We model the metabolism and behaviour of a developing cancer tumour in the context of its microenvironment, with the aim of elucidating the consequences of altered energy metabolism. Of particular interest is the Warburg Effect, a widespread preference in tumours for cytosolic glycolysis rather than oxidative phosphorylation for glucose breakdown, as yet incompletely understood. We examine a candidate explanation for the prevalence of the Warburg Effect in tumours, the acid-mediated invasion hypothesis, by generalising a canonical non-linear reaction-diffusion model of acid-mediated tumour invasion to consider additional biological features of potential importance. We apply both numerical methods and a non-standard asymptotic analysis in a travelling wave framework to obtain an explicit understanding of the range of tumour behaviours produced by the model and how fundamental parameters govern the speed and shape of invading tumour waves. Comparison with conclusions drawn under the original system--a special case of our generalised system--allows us to comment on the structural stability and predictive power of the modelling framework. PMID:23536240

  18. Digital Isothermal Quantification of Nucleic Acids via Simultaneous Chemical Initiation of Recombinase Polymerase Amplification Reactions on SlipChip

    PubMed Central

    Shen, Feng; Davydova, Elena K.; Du, Wenbin; Kreutz, Jason E.; Piepenburg, Olaf; Ismagilov, Rustem F.

    2011-01-01

    In this paper, digital quantitative detection of nucleic acids was achieved at the single-molecule level by chemical initiation of over one thousand sequence-specific, nanoliter, isothermal amplification reactions in parallel. Digital polymerase chain reaction (digital PCR), a method used for quantification of nucleic acids, counts the presence or absence of amplification of individual molecules. However it still requires temperature cycling, which is undesirable under resource-limited conditions. This makes isothermal methods for nucleic acid amplification, such as recombinase polymerase amplification (RPA), more attractive. A microfluidic digital RPA SlipChip is described here for simultaneous initiation of over one thousand nL-scale RPA reactions by adding a chemical initiator to each reaction compartment with a simple slipping step after instrument-free pipette loading. Two designs of the SlipChip, two-step slipping and one-step slipping, were validated using digital RPA. By using the digital RPA SlipChip, false positive results from pre-initiation of the RPA amplification reaction before incubation were eliminated. End-point fluorescence readout was used for “yes or no” digital quantification. The performance of digital RPA in a SlipChip was validated by amplifying and counting single molecules of the target nucleic acid, Methicillin-resistant Staphylococcus aureus (MRSA) genomic DNA. The digital RPA on SlipChip was also tolerant to fluctuations of the incubation temperature (37–42 °C), and its performance was comparable to digital PCR on the same SlipChip design. The digital RPA SlipChip provides a simple method to quantify nucleic acids without requiring thermal cycling or kinetic measurements, with potential applications in diagnostics and environmental monitoring under resource-limited settings. The ability to initiate thousands of chemical reactions in parallel on the nanoliter scale using solvent-resistant glass devices is likely to be useful for a broader range of applications. PMID:21476587

  19. Identification of human rotavirus serotype by hybridization to polymerase chain reaction-generated probes derived from a hyperdivergent region of the gene encoding outer capsid protein VP7

    SciTech Connect

    Flores, J.; Sears, J.; Schael, I.P.; White, L.; Garcia, D.; Lanata, C.; Kapikian, A.Z. (National Institutes of Health, Bethesda, MD (USA))

    1990-08-01

    We have synthesized {sup 32}P-labeled hybridization probes from a hyperdivergent region (nucleotides 51 to 392) of the rotavirus gene encoding the VP7 glycoprotein by using the polymerase chain reaction method. Both RNA (after an initial reverse transcription step) and cloned cDNA from human rotavirus serotypes 1 through 4 could be used as templates to amplify this region. High-stringency hybridization of each of the four probes to rotavirus RNAs dotted on nylon membranes allowed the specific detection of corresponding sequences and thus permitted identification of the serotype of the strains dotted. The procedure was useful when applied to rotaviruses isolated from field studies.

  20. Oxidized and acid thinned starch derivatives of hybrid maize: functional characteristics, wide-angle X-ray diffractometry and thermal properties

    Microsoft Academic Search

    O. S. Lawal; K. O. Adebowale; B. M. Ogunsanwo; L. L. Barba; N. S. Ilo

    2005-01-01

    Starch isolated from hybrid maize (8535-23) was subjected to oxidation and acid thinning. Proximate analyses revealed that moisture, ash, protein, fat, fibre, and pH reduced after oxidation and acid thinning. Percentage amylose content reduced from 20.42% in native starch to 18.76 and 17.65% in oxidised and acid thinned starch derivatives, respectively. Wide-angle X-ray diffraction patterns indicated strong peaks at 15.9°,

  1. Studies on PreIgnition Reactions of Hydrocarbon-Based Rocket Fuels Hypergolic with Red Fuming Nitric Acid as Oxidizer

    Microsoft Academic Search

    Suresh G. Kulkarni; Vrushali S. Bagalkote

    2010-01-01

    Carene, norbornadiene, ethylidene norbornene, and furfuryl alcohol exhibit hypergolic ignition with red fuming nitric acid as oxidizer. Carene, when blended with norbornadiene, ethylidene norbornene, and furfuryl alcohol in appropriate proportions, exhibits synergistic hypergolic ignition with further decrease in ignition delay. In order to understand the probable mechanism of hypergolic ignition and synergy in ignition, various pre-ignition reactions have been studied

  2. Geochemical Modeling of Reactions and Partitioning of Trace Metals and Radionuclides during Titration of Contaminated Acidic Sediments

    SciTech Connect

    Zhang, Fan [ORNL; Parker, Jack C. [University of Tennessee, Knoxville (UTK); Luo, Wensui [ORNL; Spalding, Brian Patrick [ORNL; Brooks, Scott C [ORNL; Watson, David B [ORNL; Jardine, Philip M [ORNL; Gu, Baohua [ORNL

    2008-01-01

    Many geochemical reactions that control aqueous metal concentrations are directly affected by solution pH. However, changes in solution pH are strongly buffered by various aqueous phase and solid phase precipitation/dissolution and adsorption/desorption reactions. The ability to predict acid-base behavior of the soil-solution system is thus critical to predict metal transport under variable pH conditions. This study was undertaken to develop a practical generic geochemical modeling approach to predict aqueous and solid phase concentrations of metals and anions during conditions of acid or base additions. The method of Spalding and Spalding was utilized to model soil buffer capacity and pH-dependent cation exchange capacity by treating aquifer solids as a polyprotic acid. To simulate the dynamic and pH-dependent anion exchange capacity, the aquifer solids were simultaneously treated as a polyprotic base controlled by mineral precipitation/dissolution reactions. An equilibrium reaction model that describes aqueous complexation, precipitation, sorption and soil buffering with pH-dependent ion exchange was developed using HydroGeoChem v5.0 (HGC5). Comparison of model results with experimental titration data of pH, Al, Ca, Mg, Sr, Mn, Ni, Co, and SO{sub 4}{sup 2-} for contaminated sediments indicated close agreement, suggesting that the model could potentially be used to predict the acid-base behavior of the sediment-solution system under variable pH conditions.

  3. Lewis Acid and/or Lewis Base catalyzed [3+2] cycloaddition reaction: Synthesis of pyrazoles and pyrazolines

    E-print Network

    Paris-Sud XI, Université de

    1 Lewis Acid and/or Lewis Base catalyzed [3+2] cycloaddition reaction: Synthesis of pyrazoles-Hillman adducts, activated and simple alkynes to afford 3,5-disubstituted pyrazolines and pyrazoles respectively trichloride, activated olefins, Baylis- Hillman adducts, pyrazolines, pyrazoles. Formation of heterocycles

  4. [3 + 2] Cycloaddition reactions of thioisatin with thiazolidine-2-carboxylic acid: a versatile route to new heterocyclic scaffolds

    PubMed Central

    2011-01-01

    A facile synthesis of azabicycloadducts is described by 1,3-dipolar cycloaddition reactions of thioisatin with thiazolidine-2-carboxylic acid in the presence of various electron rich and electron deficient dipolarophiles. Theoritical calculations have been performed to study the regioselectivity of products. The geometrical and energetic properties have been analyzed for the different reactants, transition states and cycloadducts formed. PMID:22373364

  5. How are the Concepts and Theories of Acid-Base Reactions Presented? Chemistry in Textbooks and as Presented by Teachers

    ERIC Educational Resources Information Center

    Furio-Mas, Carlos; Calatayud, Maria Luisa; Guisasola, Jenaro; Furio-Gomez, Cristina

    2005-01-01

    This paper investigates the views of science and scientific activity that can be found in chemistry textbooks and heard from teachers when acid-base reactions are introduced to grade 12 and university chemistry students. First, the main macroscopic and microscopic conceptual models are developed. Second, we attempt to show how the existence of…

  6. A new reaction model for the catalytic effect of silver ions on chalcopyrite leaching in sulfuric acid solutions

    Microsoft Academic Search

    Naoki Hiroyoshi; Masatoshi Arai; Hajime Miki; Masami Tsunekawa; Tsuyoshi Hirajima

    2002-01-01

    Chalcopyrite leaching in sulfuric acid solutions depends on the redox potential determined by the concentration ratio of ferric to ferrous ions, and the leaching rate is higher at redox potentials below a critical value. Previously, the authors have proposed a reaction model to interpret this phenomenon. The present study applied the model to interpret the catalytic effect of silver ions

  7. Monoclinic hafnium oxynitride supported on reduced graphene oxide to catalyse the oxygen reduction reaction in acidic media.

    PubMed

    Chisaka, M; Sasaki, H; Muramoto, H

    2014-10-14

    Monoclinic HfO2 nanoparticles were doped with nitrogen via hydrothermal treatment that avoided high-cost pyrolysis with NH3 gas in order to develop a novel oxygen reduction reaction catalyst for use in acidic media. Catalyst size reduction was achieved using a reduced graphene oxide support, and activity above 0.8 V was obtained. PMID:25167377

  8. Alcohol fuels containing wear-inhibiting amounts of reaction products of amines and phosphate esters of phosphonic acids

    SciTech Connect

    Sung, R.L.; Kaufman, B.J.; Sweeney, W.M.

    1984-03-06

    A novel fuel composition contains ethanol or gasohol plus, as a wear-inhibiting additive, a quaternary ammonium reaction product of an amine Ra-N(-(R''-O-)B-H)C-H(3-(A+C)) typically bis(2-hydroxyethyl)cocoamine and a phosphate, or phosphonic acid, typically dilauryl phosphate.

  9. A Combined Quantum Mechanical and Molecular Mechanical Study of the Reaction Mechanism and r-Amino Acidity in

    E-print Network

    Minnesota, University of

    A Combined Quantum Mechanical and Molecular Mechanical Study of the Reaction Mechanism and r-Amino Acidity in Alanine Racemase Dan Thomas Major and Jiali Gao* Contribution from the Department of Chemistry Received August 31, 2006; E-mail: gao@chem.umn.edu Abstract: Combined quantum mechanical

  10. MOTHER PLANT NUTRITION AND GROWING CONDITION AFFECT AMINO AND FATTY ACID COMPOSITIONS OF HYBRID SWEET PEPPER SEEDS

    Microsoft Academic Search

    Guohua Xu; Uzi Kafkafi; Shmuel Wolf; Yukihiro Sugimoto

    2002-01-01

    The effect of mineral nutrition status of mother plant on the concentrations of amino and fatty acids and the emergence quality of hybrid sweet pepper seeds (cv. ‘Hazera’ 1195) was studied in two hydroponics experiments. Three concentrations of potassium (K) (0.5, 2.5 and 5.0?mM) combined with NH4–N to NO3–N ratios (mM\\/mM: 0\\/6.0, 0.9\\/5.1, 1.8\\/4.2 and 3.0\\/3.0) were conducted during the

  11. Evaluation of amino acid supplementation of soybean-meal-based diets for hybrid striped bass

    E-print Network

    Savolainen, Lea Christine

    2009-05-15

    Hybrid striped bass (Morone chrysops x M. saxatilis) aquaculture is a major commercial enterprise in the United States and internationally. Efforts to decrease diet costs and limit dependence on fishmeal, have led to the development of plant...

  12. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Uses for Specific Chemical Substances § 721...rosin amidoamine reaction product (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...rosin amidoamine reaction product...

  13. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Uses for Specific Chemical Substances § 721...rosin amidoamine reaction product (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...rosin amidoamine reaction product...

  14. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Uses for Specific Chemical Substances § 721...rosin amidoamine reaction product (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...rosin amidoamine reaction product...

  15. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Uses for Specific Chemical Substances § 721...rosin amidoamine reaction product (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...rosin amidoamine reaction product...

  16. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Uses for Specific Chemical Substances § 721...rosin amidoamine reaction product (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...rosin amidoamine reaction product...

  17. Production of hybrid diesel fuel precursors from carbohydrates and petrochemicals using formic acid as a reactive solvent.

    PubMed

    Zhou, Xiaoyuan; Rauchfuss, Thomas B

    2013-02-01

    We report the one-pot alkylation of mesitylene with carbohydrate-derived 5-(hydroxymethyl)furfural (HMF) as a step toward diesel-range liquids. Using FeCl(3) as a catalyst, HMF is shown to alkylate toluene, xylene, and mesitylene in high yields in CH(2)Cl(2) and MeNO(2) solvents. Efforts to extend this reaction to greener or safer solvents showed that most ether-based solvents are unsatisfactory. Acid catalysts (e.g, p-TsOH) also proved to be ineffective. Using formic acid as a reactive solvent, mesitylene could be alkylated to give mesitylmethylfurfural (MMF) starting from fructose with yields up to approximately 70 %. The reaction of fructose with formic acid in the absence of mesitylene gave rise to low yields of the formate ester of HMF, which indicates the stabilizing effect of replacing the hydroxyl substituent with mesityl. The arene also serves as a second phase into which the product is extracted. Even by using formic acid, the mesitylation of less expensive precursors such as glucose and cellulose proceeded only in modest yields (ca. 20 %). These simpler substrates were found to undergo mesitylation by using hydrogen chloride/formic acid via the intermediate chloromethylfurfural. PMID:23281330

  18. Enhanced methanol electro-oxidation reaction on Pt-CoOx/MWCNTs hybrid electro-catalyst

    NASA Astrophysics Data System (ADS)

    Nouralishahi, Amideddin; Rashidi, Ali Morad; Mortazavi, Yadollah; Khodadadi, Abbas Ali; Choolaei, Mohammadmehdi

    2015-04-01

    The electro-catalytic behavior of Pt-CoOx/MWCNTs in methanol electro-oxidation reaction (MOR) is investigated and compared to that of Pt/MWCNTs. The electro-catalysts were synthesized by an impregnation method using NaBH4 as the reducing agent. The morphological and physical characteristics of samples are examined by XRD, TEM, ICP and EDS techniques. In the presence of CoOx, Pt nanoparticles were highly distributed on the support with an average particle size of 2 nm, an obvious decrease from 5.1 nm for Pt/MWCNTs. Cyclic voltammetry, CO-stripping, Chronoamperometry, and electrochemical impedance spectroscopy (EIS) measurements are used to study the electrochemical behavior of the electro-catalysts. The results revealed a considerable enhancement in the oxidation kinetics of COads on Pt active sites by the participation of CoOx. Compared to Pt/MWCNTs, Pt-CoOx/MWCNTs sample has a larger electrochemical active surface area (ECSA) and higher electro-catalytic activity and stability toward methanol electro-oxidation. According to the results of cyclic voltammetry, the forward anodic peak current density enhances more than 89% at the optimum atomic ratio of Pt:Co = 2:1. Furthermore, inclusion of cobalt oxide species causes the onset potential of methanol electro-oxidation reaction to shift 84 mV to negative values compared to that on Pt/MWCNTs. Based on EIS data, dehydrogenation of methanol is the rate-determining step of MOR on both Pt/MWCNTs and Pt-CoOx/MWCNTs, at small overpotentials. However, at higher overpotentials, the oxidation of adsorbed oxygen-containing groups controls the total rate of MOR process.

  19. Reaction of 2,5-bis(methoxycarbonyl)-3,4-diphenylcyclopentadienone with phosphonoacetic acid trimethyl ester

    SciTech Connect

    Fuzhenkova, A.V.; Galyautdinov, N.I.; Vagapova, N.N.

    1987-12-20

    It is known that the ease of the 1,5 migration of groups in cyclopentadienes is associated with their acceptor power. On the basis of this and in view of the tendency of phosphonoacetic acid triester to react at the C=O group of ..cap alpha..-enols (Wittig-Horner reaction), the authors studied the reactions of phosphonoacetic acid trimethyl ester with cyclones. 2,5-Bis(methoxycarbonyl)-3,4-diphenylcyclopentadienone reacts with the sodium derivative of phosphonoacetic acid trimethyl ester with the formation of adducts in which the carbanion center of the reagent is linked to the C/sup 2/ atom of cyclopentadienone. The IR spectra were determined on a UR-10 spectrometer. The PMR spectra were recorded on Varian T-60 and Tesla BS-467A spectrometer, solvent CHCl/sub 3/ or CDCl/sub 3/, internal standard TMS.

  20. Use of fast HPLC multiple reaction monitoring cubed for endogenous retinoic acid quantification in complex matrices.

    PubMed

    Jones, Jace W; Pierzchalski, Keely; Yu, Jianshi; Kane, Maureen A

    2015-03-17

    Retinoic acid (RA), an essential active metabolite of vitamin A, controls numerous physiological processes. In addition to the analytical challenges owing to its geometric isomers, low endogenous abundance, and often localized occurrence, nonspecific interferences observed during liquid chromatography (LC) multiple reaction monitoring (MRM) quantification methods have necessitated lengthy chromatography to obtain accurate quantification free of interferences. We report the development and validation of a fast high performance liquid chromatography (HPLC) multiplexing multiple reaction monitoring cubed (MRM(3)) assay for selective and sensitive quantification of endogenous RA from complex matrices. The fast HPLC separation was achieved using an embedded amide C18 column packed with 2.7 ?m fused-core particles which provided baseline resolution of endogenous RA isomers (all-trans-RA, 9-cis-RA, 13-cis-RA, and 9,13-di-cis-RA) and demonstrated significant improvements in chromatographic efficiency compared to porous particle stationary phases. Multiplexing technology further enhanced sample throughput by a factor of 2 by synchronizing parallel HPLC systems to a single mass spectrometer. The fast HPLC multiplexing MRM(3) assay demonstrated enhanced selectivity for endogenous RA quantification in complex matrices and had comparable analytical performance to robust, validated LC-MRM methodology for RA quantification. The quantification of endogenous RA using the described assay was validated on a number of mouse tissues, nonhuman primate tissues, and human plasma samples. The combined integration of fast HPLC, MRM(3), and multiplexing yields an analysis workflow for essential low-abundance endogenous metabolites that has enhanced selectivity in complex matrices and increased throughput that will be useful in efficiently interrogating the biological role of RA in larger study populations. PMID:25704261

  1. Modelling the reaction course of N -acetylneuraminic acid synthesis from N -acetyl- d -glucosamine—new strategies for the optimisation of neuraminic acid synthesis

    Microsoft Academic Search

    Vera Zimmermann; Hans-Georg Hennemann; Thomas Daußmann; Udo Kragl

    2007-01-01

    In this work, a model describing the complete enzyme catalysed synthesis of N-acetylneuraminic acid (Neu5Ac) from N-acetyl-d-glucosamine (GlcNAc) is presented. It includes the combined reaction steps of epimerisation from GlcNAc to N-acetyl-d-mannosamine (ManNAc) and the aldol condensation of ManNAc with sodium pyruvate yielding Neu5Ac. The model is expedient to\\u000a predict the reaction course for various initial and feed concentrations and

  2. Carbon nanotube/raspberry hollow Pd nanosphere hybrids for methanol, ethanol, and formic acid electro-oxidation in alkaline media.

    PubMed

    Liu, Zhelin; Zhao, Bo; Guo, Cunlan; Sun, Yujing; Shi, Yan; Yang, Haibin; Li, Zhuang

    2010-11-01

    In this paper, raspberry hollow Pd nanospheres (HPNs)-decorated carbon nanotube (CNT) was developed for electro-oxidation of methanol, ethanol, and formic acid in alkaline media. The electrocatalyst was fabricated simply by attaching HPNs onto the surface of CNT which had been functionalized by polymer wrapping. The as-prepared HPN-CNTs (CHPNs) were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). The increasing interest and intensive research on fuel cell inspire us to investigate the electrocatalytic properties of the prepared nanostructures. Besides that, previous reports about alkaline other than acidic media could supply a more active environment guide us to examine the electrocatalytic properties in alkaline electrolyte. It is found that this novel hybrid electrocatalyst exhibits excellent electrocatalytic properties and can be further applied in fuel cells, catalysts, and sensors. PMID:20692672

  3. 40 CFR 721.10570 - Cyclic amine reaction product with acetophenone and formaldehyde acid salt (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...with acetophenone and formaldehyde acid salt (generic). 721.10570 Section 721...with acetophenone and formaldehyde acid salt (generic). (a) Chemical substance...with acetophenone and formaldehyde acid salt (PMN P-08-537) is subject to...

  4. 40 CFR 721.10126 - Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...phenyl azo substituted benzenesulfonic acid copper compound (generic). 721.10126...phenyl azo substituted benzenesulfonic acid copper compound (generic). (a) Chemical...phenyl azo substituted benzenesulfonic acid copper compound (PMN P-06-689) is...

  5. 40 CFR 721.10126 - Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...phenyl azo substituted benzenesulfonic acid copper compound (generic). 721.10126...phenyl azo substituted benzenesulfonic acid copper compound (generic). (a) Chemical...phenyl azo substituted benzenesulfonic acid copper compound (PMN P-06-689) is...

  6. 40 CFR 721.10126 - Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...phenyl azo substituted benzenesulfonic acid copper compound (generic). 721.10126...phenyl azo substituted benzenesulfonic acid copper compound (generic). (a) Chemical...phenyl azo substituted benzenesulfonic acid copper compound (PMN P-06-689) is...

  7. N,N-dialkoxycarbonylamino acids from the sodium hydride-mediated reaction of alkyl chloroformates with mixed anhydrides of N-alkoxycarbonylamino acids.

    PubMed

    Benoiton, N L; Akyurekli, D; Chen, F M

    1995-05-01

    Reaction of mixed anhydride R1OCO-NHCHR2-CO-O-COOR3 for R1 = benzyl and tert-butyl and R3 = methyl, ethyl, benzyl and allyl with sodium hydride and R3OCOCl followed by acid hydrolysis gives modest yields of R1OCO-N(R3OCO)CHR2-COOH. The products are contaminated by parent acid R1OCO-NHCHR2-COOH that is not readily removed. About 75% of the acylation originates from intramolecular transfer of the alkyl carbonate moiety; the remainder comes from acylation by the alkyl chloroformate. PMID:7591486

  8. Up-Scaling Geochemical Reaction Rates Accompanying Acidic CO2-Saturated Brine Flow in Sandstone Aquifers

    E-print Network

    New York at Stoney Brook, State University of

    -scaling of anorthite and kaolinite reaction rates from pore to core scales. Unique to our simulations is the use as by a volume-averaged-concentration method. For the anorthite reaction, which remains far from equilibrium, the volume-averaged reaction rate measured for anorthite exceeded the reaction rate of the network model

  9. Hybrid Photopatterned Enzymatic Reaction (HyPER) for In situ Cell Manipulation

    PubMed Central

    Griffin, Donald R; Borrajo, Jacob; Soon, Allyson; Acosta-Vélez, Giovanny F.; Oshita, Victor; Darling, Nicole; Mack, Julia; Barker, Thomas; Iruela-Arispe, M. Luisa; Segura, Tatiana

    2014-01-01

    The ability to design artificial extracellular matrices as cell instructive scaffolds has opened the door to technologies capable of studying cell fate in vitro and to guide tissue repair in vivo. One main component of the design of artificial extracellular matrices is the incorporation of biochemical cues to guide cell phenotype and multicellular organization. The extracellular matrix is composed of a heterogeneous mixture of proteins that present a variety of spatially discrete signals to residing cell populations. In contrast, most engineered ECMs do not mimic this heterogeneity. In recent years the use of photodeprotection has been used to achieve spatial immobilization of signals. However, these approaches have been limited mostly to small peptides. Here we combine photodeprotection with enzymatic reaction to achieve spatially controlled immobilization of active bioactive signals that range from small molecules to large proteins. A peptide substrate for transglutaminase factor XIII (FXIIIa) is caged with a photodeprotectable group, which is then immobilized to the bulk of a cell compatible hydrogel. With the use of focused light the substrate can be deprotected and used to immobilize patterned bioactive signals. This approach offers an innovative strategy to immobilize delicate bioactive signals, such as growth factors, without loss of activity and enables In situ cell manipulation of encapsulated cells. PMID:24399784

  10. Unlocked nucleic acids with a pyrene-modified uracil: synthesis, hybridization studies, fluorescent properties and i-motif stability.

    PubMed

    Perlíková, Pavla; Karlsen, Kasper K; Pedersen, Erik B; Wengel, Jesper

    2014-01-01

    The synthesis of two new phosphoramidite building blocks for the incorporation of 5-(pyren-1-yl)uracilyl unlocked nucleic acid (UNA) monomers into oligonucleotides has been developed. Monomers containing a pyrene-modified nucleobase component were found to destabilize an i-motif structure at pH 5.2, both under molecular crowding and noncrowding conditions. The presence of the pyrene-modified UNA monomers in DNA strands led to decreases in the thermal stabilities of DNA*/DNA and DNA*/RNA duplexes, but these duplexes' thermal stabilities were better than those of duplexes containing unmodified UNA monomers. Pyrene-modified UNA monomers incorporated in bulges were able to stabilize DNA*/DNA duplexes due to intercalation of the pyrene moiety into the duplexes. Steady-state fluorescence emission studies of oligonucleotides containing pyrene-modified UNA monomers revealed decreases in fluorescence intensities upon hybridization to DNA or RNA. Efficient quenching of fluorescence of pyrene-modified UNA monomers was observed after formation of i-motif structures at pH 5.2. The stabilizing/destabilizing effect of pyrene-modified nucleic acids might be useful for designing antisense oligonucleotides and hybridization probes. PMID:24501777

  11. Quantitative titration of nucleic acids by enzymatic amplification reactions run to saturation.

    PubMed Central

    Pannetier, C; Delassus, S; Darche, S; Saucier, C; Kourilsky, P

    1993-01-01

    In vitro enzymatic amplification of nucleic acids by PCR or other techniques is a very sensitive method to detect rare DNA segments. We present here a protocol that allows the rapid, sensitive and precise quantification of DNA molecules using PCR amplification run to saturation. The DNA (or cDNA) to be assayed is co-amplified with known amounts of an internal standard DNA. We show that the latter must be almost identical to the assayed DNA, otherwise quantification at the plateau is unreliable. The read-out of the amplification involves one or two additional oligonucleotides. Using fluorescent oligonucleotides as primers in run-off reactions together with an automated DNA sequencer, we could measure the level of expression of several genes, like the murine MHC class I H-2Kd or a specific T cell receptor beta chain transcript in the course of an immunization. mRNA levels were normalized by measuring in a similar manner the number of transcripts encoding the housekeeping gene HPRT. Finally, our procedure might allow the rapid analysis of a large number of samples at the same time, as illustrated by the simultaneous analysis of the mRNAs encoding the CD4 and CD8 murine T cell markers. PMID:8441670

  12. Quantitative titration of nucleic acids by enzymatic amplification reactions run to saturation.

    PubMed

    Pannetier, C; Delassus, S; Darche, S; Saucier, C; Kourilsky, P

    1993-02-11

    In vitro enzymatic amplification of nucleic acids by PCR or other techniques is a very sensitive method to detect rare DNA segments. We present here a protocol that allows the rapid, sensitive and precise quantification of DNA molecules using PCR amplification run to saturation. The DNA (or cDNA) to be assayed is co-amplified with known amounts of an internal standard DNA. We show that the latter must be almost identical to the assayed DNA, otherwise quantification at the plateau is unreliable. The read-out of the amplification involves one or two additional oligonucleotides. Using fluorescent oligonucleotides as primers in run-off reactions together with an automated DNA sequencer, we could measure the level of expression of several genes, like the murine MHC class I H-2Kd or a specific T cell receptor beta chain transcript in the course of an immunization. mRNA levels were normalized by measuring in a similar manner the number of transcripts encoding the housekeeping gene HPRT. Finally, our procedure might allow the rapid analysis of a large number of samples at the same time, as illustrated by the simultaneous analysis of the mRNAs encoding the CD4 and CD8 murine T cell markers. PMID:8441670

  13. Tailoring the composition of ultrathin, ternary alloy PtRuFe nanowires for the methanol oxidation reaction and formic acid oxidation reaction

    DOE PAGESBeta

    Scofield, Megan E.; Koenigsmann, Christopher; Wang, Lei; Lui, Haiqing; Wong, Stanislaus S.

    2015-01-01

    In the search for alternatives to conventional Pt electrocatalysts, we have synthesized ultrathin, ternary PtRuFe nanowires (NW), possessing different chemical compositions in order to probe their CO tolerance as well as electrochemical activity as a function of composition for both (i) the methanol oxidation reaction (MOR) and (ii) the formic acid oxidation reaction (FAOR). As-prepared ‘multifunctional’ ternary NW catalysts exhibited both higher MOR and FAOR activity as compared with binary Pt?Ru? NW, monometallic Pt NW, and commercial catalyst control samples. In terms of synthetic novelty, we utilized a sustainably mild, ambient wet-synthesis method never previously applied to the fabrication ofmore »crystalline, pure ternary systems in order to fabricate ultrathin, homogeneous alloy PtRuFe NWs with a range of controlled compositions. These NWs were subsequently characterized using a suite of techniques including XRD, TEM, SAED, and EDAX in order to verify not only the incorporation of Ru and Fe into the Pt lattice but also their chemical homogeneity, morphology, as well as physical structure and integrity. Lastly, these NWs were electrochemically tested in order to deduce the appropriateness of conventional explanations such as (i) the bi-functional mechanism as well as (ii) the ligand effect to account for our MOR and FAOR reaction data. Specifically, methanol oxidation appears to be predominantly influenced by the Ru content, whereas formic acid oxidation is primarily impacted by the corresponding Fe content within the ternary metal alloy catalyst itself.« less

  14. Tailoring the composition of ultrathin, ternary alloy PtRuFe nanowires for the methanol oxidation reaction and formic acid oxidation reaction

    DOE PAGESBeta

    Scofield, Megan E. [State Univ. of New York at Stony Brook, Stony Brook, NY (United States); Koenigsmann, Christopher [State Univ. of New York at Stony Brook, Stony Brook, NY (United States); Wang, Lei [State Univ. of New York at Stony Brook, Stony Brook, NY (United States); Lui, Haiqing [State Univ. of New York at Stony Brook, Stony Brook, NY (United States); Wong, Stanislaus S. [State Univ. of New York at Stony Brook, Stony Brook, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-01-01

    In the search for alternatives to conventional Pt electrocatalysts, we have synthesized ultrathin, ternary PtRuFe nanowires (NW), possessing different chemical compositions in order to probe their CO tolerance as well as electrochemical activity as a function of composition for both (i) the methanol oxidation reaction (MOR) and (ii) the formic acid oxidation reaction (FAOR). As-prepared ‘multifunctional’ ternary NW catalysts exhibited both higher MOR and FAOR activity as compared with binary Pt?Ru? NW, monometallic Pt NW, and commercial catalyst control samples. In terms of synthetic novelty, we utilized a sustainably mild, ambient wet-synthesis method never previously applied to the fabrication of crystalline, pure ternary systems in order to fabricate ultrathin, homogeneous alloy PtRuFe NWs with a range of controlled compositions. These NWs were subsequently characterized using a suite of techniques including XRD, TEM, SAED, and EDAX in order to verify not only the incorporation of Ru and Fe into the Pt lattice but also their chemical homogeneity, morphology, as well as physical structure and integrity. Lastly, these NWs were electrochemically tested in order to deduce the appropriateness of conventional explanations such as (i) the bi-functional mechanism as well as (ii) the ligand effect to account for our MOR and FAOR reaction data. Specifically, methanol oxidation appears to be predominantly influenced by the Ru content, whereas formic acid oxidation is primarily impacted by the corresponding Fe content within the ternary metal alloy catalyst itself.

  15. Nucleic acid templated uncaging of fluorophores using Ru-catalyzed photoreduction with visible light.

    PubMed

    Röthlingshöfer, Manuel; Gorska, Katarzyna; Winssinger, Nicolas

    2012-01-20

    Hybridization-based reactions have attracted significant attention. The nucleic acid templated photocatalyzed azide reduction using catalytic amounts of a [Ru(bpy)(2)phen](2+) conjugate is reported. The reaction could be performed with as little as 2% of the Ru nucleic acid probe and was shown to productively unquench 7-azido-coumarin as well as uncage a small molecule. PMID:22206275

  16. Formation of red pigment by a two-step 2-thiobarbituric acid reaction of alka-2,4-dienals. Potential products of lipid oxidation

    Microsoft Academic Search

    Hiroko Kosugi; Tetsuta Katob; Kiyomi Kikugawab

    1988-01-01

    Reaction of 2,4-hexadienal, 2,4-nonadienal and 2,4-decadienal with 2-thiobarbituric acid (TBA) in aqueous acetic acid produced\\u000a a 532-nm absorbing red pigment. While the 1?1 reaction of the aldehyde and TBA produced little pigment, reaction of the aldehyde\\u000a with an excess amount of TBA produced significant amounts. Instant heating of the reaction mixture did not produce the pigment.\\u000a However, initial reaction at

  17. The gas-phase acidity of hindered amines and some reaction chemistry of their corresponding amide ions

    NASA Astrophysics Data System (ADS)

    Damrauer, Robert; Krempp, Michele; O'Hair, Richard A. J.; Simon, Roger A.

    1992-09-01

    The gas-phase acidities of three hindered amines have been determined by equilibrium measurements using tandem flowing afterglow-selected-ion flow tube technology. These amines, tert-butylamine ([Delta]H°acid = 396.6 kcal mol-1), di-sec-butylamine ([Delta]H°acid = 386.1 kcal mol-1), and 2,2,6,6-tetramethylpiperidine ([Delta]H°acid = 387.5 kcal mol-1), were chosen because of their hindered nature and differing substitution patterns. The ion/molecule chemistry of the anions corresponding to these amides was studied in detail. This demonstrated quite different reactivity patterns, which are discussed in terms of steric properties and other structural features. Thus, primary and secondary substituted amides can be differentiated by reactions with N2O and ND3, and di-sec-butylamide has a strong tendency to act as a hydride donor.

  18. A highly sensitive photoelectrochemical detection of perfluorooctanic acid with molecularly imprined polymer-functionalized nanoarchitectured hybrid of AgI-BiOI composite.

    PubMed

    Gong, Jingming; Fang, Tian; Peng, Dinghua; Li, Aimin; Zhang, Lizhi

    2015-11-15

    A rapid and ultrasensitive signal-off photoelectrochemical sensor has been developed under visible-light irradiation, for the detection of perfluorooctanoic acid (PFOA), especially low level PFOA present in environment, whereby a novel nanostructured probe made of molecularly imprinted polymer (MIP) modified AgI nanoparticles-BiOI nanoflake arrays (AgI-BiOINFs) is designed as the photoactive electrode (denoted as MIP@AgI-BiOINFs). Here, the unique nanoarchitectured hybrid of AgI-BiOINFs was first in situ synthesized via a facile successive ionic layer adsorption and reaction (SILAR) approach and then employed as a matrix to graft the recognition element of MIP. Such a newly designed PEC sensor exhibits high sensitivity and selectivity for the determination of PFOA. The PEC analysis is highly linear over the PFOA concentration ranging from 0.02 to 1000.0ppb with a detection limit of 0.01ppb (S/N=3). This value obtained by using the facile PEC sensor is comparable to the results obtained by using well-established liquid chromatography-tandem mass spectrometry (LC-MS/MS). Toward practical applications, this low-cost and sensitive assay was successfully applied to measure PFOA in real water samples. PMID:26092130

  19. Quantitative determination of isoquinoline alkaloids and chlorogenic acid in Berberis species using ultra high performance liquid chromatography with hybrid triple quadrupole linear ion trap mass spectrometry.

    PubMed

    Singh, Awantika; Bajpai, Vikas; Kumar, Sunil; Arya, Kamal Ram; Sharma, Kulwant Rai; Kumar, Brijesh

    2015-06-01

    Berberis species are well known and used extensively as medicinal plants in traditional medicine. They have many medicinal values attributable to the presence of alkaloids having different pharmacological activities. In this study, a method was developed and validated as per international conference on harmonization guidelines using ultra high performance liquid chromatography with hybrid triple quadrupole-linear ion trap mass spectrometry operated in the multiple reaction monitoring mode for nine bioactive compounds, including protoberberine alkaloids, aporphine alkaloids and chlorogenic acid. This method was applied in different plant parts of eight Berberis species to determine variations in content of nine bioactive compounds. The separation was achieved on an ACQUITY UPLC CSH™ C18 column using a gradient mobile phase at flow rate 0.3 mL/min. Calibration curves for all the nine analytes provided optimum linear detector response (with R(2) ?0.9989) over the concentration range of 0.5-1000 ng/mL. The precision and accuracy were within RSDs ?2.4 and ?2.3%, respectively. The results indicated significant variation in the total contents of the nine compounds in Berberis species. PMID:25847792

  20. Trifluoroacetic acid in 2,2,2-trifluoroethanol facilitates S(N)Ar reactions of heterocycles with arylamines.

    PubMed

    Carbain, Benoit; Coxon, Christopher R; Lebraud, Honorine; Elliott, Kristopher J; Matheson, Christopher J; Meschini, Elisa; Roberts, Amy R; Turner, David M; Wong, Christopher; Cano, Celine; Griffin, Roger J; Hardcastle, Ian R; Golding, Bernard T

    2014-02-17

    Small-molecule drug discovery requires reliable synthetic methods for attaching amino compounds to heterocyclic scaffolds. Trifluoroacetic acid-2,2,2-trifluoroethanol (TFA-TFE) is as an effective combination for achieving SN Ar reactions between anilines and heterocycles (e.g., purines and pyrimidines) substituted with a leaving group (fluoro-, chloro-, bromo- or alkylsulfonyl). This method provides a variety of compounds containing a "kinase-privileged fragment" associated with potent inhibition of kinases. TFE is an advantageous solvent because of its low nucleophilicity, ease of removal and ability to solubilise polar substrates. Furthermore, TFE may assist the breakdown of the Meisenheimer-Jackson intermediate by solvating the leaving group. TFA is a necessary and effective acidic catalyst, which activates the heterocycle by N-protonation without deactivating the aniline by conversion into an anilinium species. The TFA-TFE methodology is compatible with a variety of functional groups and complements organometallic alternatives, which are often disadvantageous because of the expense of reagents, the frequent need to explore diverse sets of reaction conditions, and problems with product purification. In contrast, product isolation from TFA-TFE reactions is straightforward: evaporation of the reaction mixture, basification and chromatography affords analytically pure material. A total of 45 examples are described with seven discrete heterocyclic scaffolds and 2-, 3- and 4-substituted anilines giving product yields that are normally in the range 50-90?%. Reactions can be performed with either conventional heating or microwave irradiation, with the latter often giving improved yields. PMID:24458729

  1. Trio catalysis merging enamine, brønsted Acid, and metal lewis Acid catalysis: asymmetric three-component aza-diels-alder reaction of substituted cinnamaldehydes, cyclic ketones, and arylamines.

    PubMed

    Deng, Yongming; Kumar, Siddhartha; Wheeler, Kraig; Wang, Hong

    2015-05-18

    A trio catalyst system, composed of arylamine, BINOL-derived phosphoric acid, and Y(OTf)3 , enables the combination of enamine catalysis with both hard metal Lewis acid catalysis and Brønsted acid catalysis for the first time. Using this catalyst system, a three-component aza-Diels-Alder reaction of substituted cinnamaldehyde, cyclic ketone, and arylamine is carried out with high chemo- and enantioselectivity, affording a series of optically active 1,4-dihydropyridine (DHP) derivatives are obtained in 91-99?%?ee and 59-84?% yield. DHPs bearing a chiral quaternary carbon center are also obtained with good enantioselectivity and moderate yield (three examples). Preliminary mechanistic investigations have also been conducted. PMID:25877134

  2. Complex chemical composition of colored surface films formed from reactions of propanal in sulfuric acid at upper troposphere/lower stratosphere aerosol acidities

    NASA Astrophysics Data System (ADS)

    Van Wyngarden, A. L.; Pérez-Montaño, S.; Bui, J. V. H.; Li, E. S. W.; Nelson, T. E.; Ha, K. T.; Leong, L.; Iraci, L. T.

    2015-04-01

    Particles in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40-80 wt%) in water. However, airborne measurements have shown that these particles also contain a significant fraction of organic compounds of unknown chemical composition. Acid-catalyzed reactions of carbonyl species are believed to be responsible for significant transfer of gas phase organic species into tropospheric aerosols and are potentially more important at the high acidities characteristic of UT/LS particles. In this study, experiments combining sulfuric acid (H2SO4) with propanal and with mixtures of propanal with glyoxal and/or methylglyoxal at acidities typical of UT/LS aerosols produced highly colored surface films (and solutions) that may have implications for aerosol properties. In order to identify the chemical processes responsible for the formation of the surface films, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and 1H nuclear magnetic resonance (NMR) spectroscopies were used to analyze the chemical composition of the films. Films formed from propanal were a complex mixture of aldol condensation products, acetals and propanal itself. The major aldol condensation products were the dimer (2-methyl-2-pentenal) and 1,3,5-trimethylbenzene that was formed by cyclization of the linear aldol condensation trimer. Additionally, the strong visible absorption of the films indicates that higher-order aldol condensation products must also be present as minor species. The major acetal species were 2,4,6-triethyl-1,3,5-trioxane and longer-chain linear polyacetals which are likely to separate from the aqueous phase. Films formed on mixtures of propanal with glyoxal and/or methylglyoxal also showed evidence of products of cross-reactions. Since cross-reactions would be more likely than self-reactions under atmospheric conditions, similar reactions of aldehydes like propanal with common aerosol organic species like glyoxal and methylglyoxal have the potential to produce significant organic aerosol mass and therefore could potentially impact chemical, optical and/or cloud-forming properties of aerosols, especially if the products partition to the aerosol surface.

  3. 40 CFR 721.10428 - Fatty acids, C18-unsatd., dimers, reaction products with 1-piperazineethanamine.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...New Uses for Specific Chemical Substances § 721...unsatd., dimers, reaction products with 1-piperazineethanamine. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...unsatd., dimers, reaction products with...

  4. 40 CFR 721.10428 - Fatty acids, C18-unsatd., dimers, reaction products with 1-piperazineethanamine.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...New Uses for Specific Chemical Substances § 721...unsatd., dimers, reaction products with 1-piperazineethanamine. (a) Chemical substance and significant...reporting. (1) The chemical substance identified...unsatd., dimers, reaction products with...

  5. 40 CFR 721.10448 - Acetic acid, hydroxy- methoxy-, methyl ester, reaction products with substituted alkylamine...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...New Uses for Specific Chemical Substances § 721...methoxy-, methyl ester, reaction products with substituted...generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydroxymethoxy-, methyl ester, reaction products with...

  6. 40 CFR 721.9485 - Dimer acid/polymerized rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Uses for Specific Chemical Substances § 721...rosin amidoamine reaction product (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...rosin amidoamine reaction product (PMN...

  7. 40 CFR 721.9485 - Dimer acid/polymerized rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Uses for Specific Chemical Substances § 721...rosin amidoamine reaction product (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...rosin amidoamine reaction product (PMN...

  8. 40 CFR 721.9485 - Dimer acid/polymerized rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Uses for Specific Chemical Substances § 721...rosin amidoamine reaction product (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...rosin amidoamine reaction product (PMN...

  9. 40 CFR 721.10448 - Acetic acid, hydroxy- methoxy-, methylester, reaction products with substituted alkylamine...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...New Uses for Specific Chemical Substances § 721...methoxy-, methylester, reaction products with substituted...generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...hydroxymethoxy-, methyl ester, reaction products with...

  10. 40 CFR 721.9485 - Dimer acid/polymerized rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Uses for Specific Chemical Substances § 721...rosin amidoamine reaction product (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...rosin amidoamine reaction product (PMN...

  11. 40 CFR 721.9485 - Dimer acid/polymerized rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Uses for Specific Chemical Substances § 721...rosin amidoamine reaction product (generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...rosin amidoamine reaction product (PMN...

  12. 40 CFR 721.10570 - Cyclic amine reaction product with acetophenone and formaldehyde acid salt (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...New Uses for Specific Chemical Substances § 721.10570 Cyclic amine reaction product with acetophenone...generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified generically as cyclic amine reaction product with...

  13. Lewis base mediated ?-elimination and Lewis acid mediated insertion reactions of disilazido zirconium compounds.

    PubMed

    Yan, KaKing; Duchimaza Heredia, Juan J; Ellern, Arkady; Gordon, Mark S; Sadow, Aaron D

    2013-10-01

    The reactivity of a series of disilazido zirconocene complexes is dominated by the migration of anionic groups (hydrogen, alkyl, halide, OTf) between the zirconium and silicon centers. The direction of these migrations is controlled by the addition of two-electron donors (Lewis bases) or two-electron acceptors (Lewis acids). The cationic nonclassical [Cp2ZrN(SiHMe2)2](+) ([2](+)) is prepared from Cp2Zr{N(SiHMe2)2}H (1) and B(C6F5)3 or [Ph3C][B(C6F5)4], while reactions of B(C6F5)3 and Cp2Zr{N(SiHMe2)2}R (R = Me (3), Et (5), n-C3H7 (7), CH?CHSiMe3 (9)) provide a mixture of [2](+) and [Cp2ZrN(SiHMe2)(SiRMe2)](+). The latter products are formed through B(C6F5)3 abstraction of a ?-H and R group migration from Zr to the ?-Si center. Related ?-hydrogen abstraction and X group migration reactions are observed for Cp2Zr{N(SiHMe2)2}X (X = OTf (11), Cl (13), OMe (15), O-i-C3H7 (16)). Alternatively, addition of DMAP (DMAP = 4-(dimethylamino)pyridine) to [2](+) results in coordination to a Si center and hydrogen migration to zirconium, giving the cationic complex [Cp2Zr{N(SiHMe2)(SiMe2DMAP)}H](+) ([19](+)). Related hydrogen migration occurs from [Cp2ZrN(SiHMe2)(SiMe2OCHMe2)](+) ([18](+)) to give [Cp2Zr{N(SiMe2DMAP)(SiMe2OCHMe2)}H](+) ([22](+)), whereas X group migration is observed upon addition of DMAP to [Cp2ZrN(SiHMe2)(SiMe2X)](+) (X = OTf ([12](+)), Cl ([14](+))) to give [Cp2Zr{N(SiHMe2)(SiMe2DMAP)}X](+) (X = OTf ([26](+)), Cl ([20](+))). The species involved in these transformations are described by resonance structures that suggest ?-elimination. Notably, such pathways are previously unknown in early metal amide chemistry. Finally, these migrations facilitate direct Si-H addition to carbonyls, which is proposed to occur through a pathway that previously had been reserved for later transition metal compounds. PMID:24067161

  14. Source and reaction pathways of dicarboxylic acids, ketoacids and dicarbonyls in arctic aerosols: One year of observations

    NASA Astrophysics Data System (ADS)

    Kawamura, Kimitaka; Kasukabe, Hideki; Barrie, Leonard A.

    Normal saturated (C 2?C 11) and unsaturated (C 4?C 5, C 8) dicarboxylic acids were measured in arctic aerosol samples collected weekly at Alert, Canada in 1987-1988. In all seasons, oxalic (C 2) acid was usually the dominant diacid species (1.8-70 ng m -3, av. 14 ± 12 ng m -3) followed by malonic (C 3; 0.05-19 ng m -3, av. 2.5 ± 3.3 ng m -3) and succinic (C 4; 0.51-18 ng m -3, av. 3.8 ± 3.5 ng m -3) acids. The total concentrations of dicarboxylic acids showed a seasonal variation (4.3-97 ng m -3, av. 25 ± 20 ng m -3),with two maxima in September to October and in March to April. The autumn peak is characterized by high concentrations of oxalic acid and azelaic (C 9) acids, which were probably caused by enhanced contributions from anthropogenic and biogenic sources, respectively, followed by photochemical reactions. This is consistent with higher concentrations of n-alkanes from terrestrial plant waxes and of soil-derived aluminum in the autumn aerosol samples. On the other hand, during "Arctic Sunrise" in March to April, oxalic, malonic and succinic acids as well as some other (C 5?C 6) diacids were 5 to 20 times more abundant than in the preceding dark winter months, suggesting that diacids are produced in situ by secondary photochemical oxidation of organic pollutants carried to the Arctic. ?-Oxocarboxylic acids (C 2?C 5, C 9), pyruvic acid and ?-dicarbonyls (methylglyoxal and glyoxal) were also detected in the arctic aerosols. Their concentration also showed spring maxima; however, they were observed a few weeks earlier than the spring peak of diacids. The ?-oxoacids are likely intermediates to the production of ?,?-dicarboxylic acids at the polar sunrise.

  15. Kinetics of liquid-solid reactions in naphthenic acid conversion and Kraft pulping

    Microsoft Academic Search

    Ling Yang

    2009-01-01

    Two liquid-solid reactions, in which the morphology of the solid changes as the reactions proceeds, were examined. One is the NA conversion in oil by decarboxylation on metal oxides and carbonates, and the other is the Kraft pulping in which lignin removal by delignification reaction. In the study of the NA conversion, CaO was chosen as the catalyst for the

  16. New entries in Lewis acid-Lewis base bifunctional asymmetric catalyst: catalytic enantioselective Reissert reaction of pyridine derivatives.

    PubMed

    Ichikawa, Eiko; Suzuki, Masato; Yabu, Kazuo; Albert, Matthias; Kanai, Motomu; Shibasaki, Masakatsu

    2004-09-29

    The first catalytic enantioselective Reissert reaction of pyridine derivatives that affords products with excellent regio- and enantioselectivity is described. The key for success is the development of new Lewis acid-Lewis base bifunctional asymmetric catalysts containing an aluminum as a Lewis acid and sulfoxides or phosphine sulfides as a Lewis base. These reactions are useful for the synthesis of a variety of chiral piperidine subunits, and catalytic enantioselective formal synthesis of CP-293,019, a selective D4 receptor antagonist, was achieved. Preliminary mechanistic studies indicated that both sulfoxides and phosphine sulfides can activate TMSCN as a Lewis base. In addition, the sulfoxides with appropriate stereochemistry might stabilize a highly enantioselective bimetallic complex (a presumed active catalyst) through internal coordination to aluminum. PMID:15382912

  17. A comparative study on reactions of n-alkylamines with tungstic acids with various W–O octahedral layers: Novel evidence for the “dissolution–reorganization” mechanism

    Microsoft Academic Search

    Deliang Chen; Tao Li; Li Yin; Xianxiang Hou; Xiujun Yu; Yang Zhang; Bingbing Fan; Hailong Wang; Xinjian Li; Rui Zhang; Tiecui Hou; Hongxia Lu; Hongliang Xu; Jing Sun; Lian Gao

    2011-01-01

    The aim of this paper was to provide a convincing experimental research to demonstrate a dissolution–reorganization mechanism for the formation of tungstate-based inorganic–organic hybrid nanobelts by comparatively investigating the reaction behaviors of H2WO4 and H2W2O7·xH2O with n-alkylamines (CmH2m+1NH2, m=4–10). The formation of tungstate-based hybrid nanobelts derived from the reactions between n-alkylamines and H2WO4 with single-octahedral W–O layers was investigated with

  18. Alkyl substituent effects on gas-phase acidities - The influence of hybridization.

    NASA Technical Reports Server (NTRS)

    Brauman, J. I.; Blair, L. K.

    1971-01-01

    Exploration of the effect on acidity of alkyl groups bonded to trigonal and digonal carbon. Some results on the relative acidities of toluene and p-xylene, and acetylene and substitute acetylenes, as determined by ion cyclotron resonance (icr) spectroscopy, are described. Some limitations of the CNDO/2 calculation method are discussed.

  19. Amplified electrochemiluminescence of luminol based on hybridization chain reaction and in situ generate co-reactant for highly sensitive immunoassay.

    PubMed

    Xiao, Lijuan; Chai, Yaqin; Yuan, Ruo; Cao, Yaling; Wang, Haijun; Bai, Lijuan

    2013-10-15

    In this work, we described a simple and highly sensitive electrochemiluminescence (ECL) strategy for IgG detection. Firstly, L-cysteine functionalized reduced graphene oxide composite (L-cys-rGO) was decorated on the glassy carbon electrode (GCE) surface. Then anti-IgG was immobilized on the modified electrode surface through the interaction between the carboxylic groups of the L-cys-rGO and the amine groups in anti-IgG. And then biotinylated anti-IgG (bio-anti-IgG) was assembled onto the electrode surface based on the sandwich-type immunoreactions. By the conjunction of biotin and streptavidin (SA), SA was immobilized, which in turn, combined with the biotin labeled initiator strand (S1). In the presence of two single DNA strands of glucose oxidase labeled S2 (GOD-S2) and complementary strand (S3), S1 could trigger the hybridization chain reaction (HCR) among S1, GOD-S2 and S3. Herein, due to HCR, numerous GOD was efficiently immobilizated on the sensing surface and exhibited excellent catalysis towards glucose to in situ generate amounts of hydrogen peroxide (H2O2), which acted as luminol's co-reactant to significantly enhance the ECL signal. The proposed ECL immunosensor presented predominate stability and high sensibility for determination of IgG in the range from 0.1 pg mL(-1) to 100 ng mL(-1) with a detection limit of 33 fg mL(-1) (S/N=3). Additionally, the designed ECL immunosensor exhibited a promising application for other protein detection. PMID:24054635

  20. The drastic effect of platinum on carbon-supported ruthenium-tin catalysts used for hydrogenation reactions of carboxylic acids

    Microsoft Academic Search

    Yoshinori Hara; Kouetsu Endou

    2003-01-01

    The incorporation of platinum on bimetallic ruthenium-tin catalysts supported on active carbon has profound effects on the catalytic behavior. The reaction rate was accelerated nearly three times compared with that of the bimetallic system for the hydrogenation of 1,4-cyclohexanedicarboxylic acid (CHDA). Moreover, it turned out that Pt can completely prevent Sn, one component of the catalyst, from dissolving into the

  1. The acidity and catalytic behavior of Mg-ZSM-5 prepared via a solid-state reaction

    Microsoft Academic Search

    Yu-Guang Li; Wei-Hong Xie; Shen Yong

    1997-01-01

    A series of Mg-ZSM-5 zeolite catalysts with different content of magnesium were prepared via a solid-state reaction of HZSM-5 with magnesium chloride at 327°C. X-ray determinations demonstrated that the structure and crystallinity of the catalysts were not changed as compared with HZSM-5 zeolite. The acidity of the catalysts was characterized by temperature programmed desorption of ammonia and infrared spectra of

  2. Kinetic behaviour of the malonaldehyde-thiobarbituric acid reaction. kinetic-fluorimetric determination of malonaldehyde in human serum

    Microsoft Academic Search

    Anunciacion Espinosa-Mansilla; Isabel Durán Merás; Francisco Salinas López

    1996-01-01

    For the first time a fluorimetric-kinetic method for the determination of malonaldehyde (MLD) is proposed. The fluorescence emission of the thiobarbituric acid (TBA)-MLD reaction product has been monitored at 553 nm (excitation wavelength 515 nm), and the instrumental and experimental variables have been studied. A selective and fast kinetic-fluorimetric determination of malonaldehyde is proposed. The sensitivity of the method is

  3. A study of rates of reaction of some substituted benzoic acids and diphenyldiazomethane 

    E-print Network

    Westmoreland, John Sherman

    1957-01-01

    hours B after which it was distilled through a twelve-bulb Snyder column under anhydrous conditions. The middle seventy per cent of each batch was used. Benzoic Acid ? This acid, purchased from the Mallinckrodt Chemical &orks was analytical reagents...

  4. Rheological Properties and Reaction Kinetics of Amidoamine Oxide Surfactants-based Acids with Calcite 

    E-print Network

    Li, Lingling

    2012-07-16

    A new type of viscoelastic amphoteric surfactants (amidoamine oxide) has been examined as a diverting agent during acidizing treatment. Rheological properties of viscoelastic surfactants are a function of surfactant concentration, acid additives, p...

  5. Fluorescence In Situ Hybridization Assay Using Peptide Nucleic Acid Probes for Differentiation between Tuberculous and Nontuberculous Mycobacterium Species in Smears of Mycobacterium Cultures

    Microsoft Academic Search

    HENRIK STENDER; KAARE LUND; KENNETH H. PETERSEN; OLE F. RASMUSSEN; POONPILAS HONGMANEE; HÅKAN MIORNER; SVEN E. GODTFREDSEN

    1999-01-01

    TB PNA FISH is a new fluorescence in situ hybridization (FISH) method using peptide nucleic acid (PNA) probes for differentiation between species of the Mycobacterium tuberculosis complex (MTC) and nontubercu- lous mycobacteria (NTM) in acid-fast bacillus-positive (AFB1) cultures is described. The test is based on fluorescein-labelled PNA probes that target the rRNA of MTC or NTM species applied to smears

  6. Multidimensional separation of chiral amino acid mixtures in a multilayered three-dimensional hybrid microfluidic/nanofluidic device.

    PubMed

    Kim, Bo Young; Yang, Jing; Gong, Maojun; Flachsbart, Bruce R; Shannon, Mark A; Bohn, Paul W; Sweedler, Jonathan V

    2009-04-01

    Microscale total analysis systems (microTAS) allow high-throughput analyses by integrating multiple processes, parallelization, and automation. Here we combine unit operations of microTAS to create a device that can perform multidimensional separations using a three-dimensional hybrid microfluidic/nanofluidic device composed of alternating layers of patterned poly(methyl methacrylate) and nanocapillary array membranes constructed from nuclear track-etched polycarbonate. Two consecutive electrophoretic separations are performed, the first being an achiral separation followed by a chiral separation of a selected analyte band. Separation conditions are optimized for a racemic mixture of fluorescein-isothiocyanate-labeled amino acids, serine and aspartic acid, chosen because there are endogenous D-forms of these amino acids in animals. The chiral separation is implemented using micellar electrokinetic chromatography using beta-cyclodextrin as the chiral selector and sodium taurocholate as the micelle-forming agent. Analyte separation is monitored by dual-beam laser-induced fluorescence detection. After separation in the first electrophoretic channel, the preselected analyte is sampled by the second-stage separation using an automated collection sequence with a zero-crossing algorithm. The controlled fluidic environment inherent to the three-dimensional architecture enables a series of separations in varying fluidic environments and allows sample stacking via different background electrolyte pH conditions. The ability to interface sequential separations, selected analyte capture, and other fluidic manipulations in the third dimension significantly improves the functionality of multilayer microfluidic devices. PMID:19271741

  7. Rapid identification, by use of the LTQ Orbitrap hybrid FT mass spectrometer, of antifungal compounds produced by lactic acid bacteria.

    PubMed

    Brosnan, Brid; Coffey, Aidan; Arendt, Elke K; Furey, Ambrose

    2012-07-01

    Fungal contamination of food causes health and economic concerns. Several species of lactic acid bacteria (LAB) have antifungal activity which may inhibit food spoilage fungi. LAB have GRAS (generally recognised as safe) status, allowing them to be safely integrated into food systems as natural food preservatives. A method is described herein that enables rapid screening of LAB cultures for 25 known antifungal compounds associated with LAB. This is the first chromatographic method developed which enables the rapid identification of a wide range of antifungal compounds by a single method with a short analysis time (23 min). Chromatographic separation was achieved on a Phenomenex Gemini C18 100A column (150 mm?×?2.0 mm; 5 ?m) by use of a mobile-phase gradient prepared from (A) water containing acetic acid (0.1%) and (B) acetonitrile containing acetic acid (0.1%), at a flow rate of 0.3 µL min(-1). The gradient involved a progressive ramp from 10-95% acetonitrile over 13 min. The LC was coupled to a hybrid LTQ Orbitrap XL fourier-transform mass spectrometer (FTMS) operated in negative ionisation mode. High mass accuracy data (<3 ppm) obtained by use of high resolution (30,000 K) enabled unequivocal identification of the target compounds. This method allows comprehensive profiling and comparison of different LAB strains and is also capable of the identification of additional compounds produced by these bacteria. PMID:22526638

  8. Quantification of Syntrophic Fatty Acid-?-Oxidizing Bacteria in a Mesophilic Biogas Reactor by Oligonucleotide Probe Hybridization

    PubMed Central

    Hansen, Kaare H.; Ahring, Birgitte K.; Raskin, Lutgarde

    1999-01-01

    Small-subunit rRNA sequences were obtained for two saturated fatty acid-?-oxidizing syntrophic bacteria, Syntrophomonas sapovorans and Syntrophomonas wolfei LYB, and sequence analysis confirmed their classification as members of the family Syntrophomonadaceae. S. wolfei LYB was closely related to S. wolfei subsp. wolfei, but S. sapovorans did not cluster with the other members of the genus Syntrophomonas. Five oligonucleotide probes targeting the small-subunit rRNA of different groups within the family Syntrophomonadaceae, which contains all currently known saturated fatty acid-?-oxidizing syntrophic bacteria, were developed and characterized. The probes were designed to be specific at the family, genus, and species levels and were characterized by temperature-of-dissociation and specificity studies. To demonstrate the usefulness of the probes for the detection and quantification of saturated fatty acid-?-oxidizing syntrophic bacteria in methanogenic environments, the microbial community structure of a sample from a full-scale biogas plant was determined. Hybridization results with probes for syntrophic bacteria and methanogens were compared to specific methanogenic activities and microbial numbers determined with most-probable-number estimates. Most of the methanogenic rRNA was comprised of Methanomicrobiales rRNA, suggesting that members of this order served as the main hydrogen-utilizing microorganisms. Between 0.2 and 1% of the rRNA was attributed to the Syntrophomonadaceae, of which the majority was accounted for by the genus Syntrophomonas. PMID:10543784

  9. Visible light-induced reactions of humic acids on TiO 2

    Microsoft Academic Search

    Youngmin Cho; Wonyong Choi

    2002-01-01

    We investigated the sensitized degradation of humic acids on TiO2 under visible light (?>420nm) irradiation. The photolysis rates were strongly dependent on pH due to the pH-dependent adsorption of humic acids on TiO2 with the maximum rate observed at pH?3. Reduction in the UV–visible absorbance and fluorescence emission (?ex=350nm) of humic acids was observed during the irradiation. Humic acids acted

  10. An investigation of vitamin B-6 catalyzed reactions of some aminophosphonic acids in model systems

    E-print Network

    Langohr, Michael Frederick

    1975-01-01

    , and love this work would not have been possible. TABLE OP CONTEKTS Introduction Transamination Racemization Beta-elimination Gamma-elimination Carbon-carbon Bond CleavaEe Decarboxylation Oxidative Deamination Aminophosphonic Acids 8 13 15... of an Optically Active Amino acid The Mechanism of Beta-elimination 6 A Mechansim for Gamma-elimination 7 The Mechanism of Degradation (or synthesis) of Beta-hydroxy-alpha Amino Acids 8 A Mechanism for Decarboxylation of an Amino Acid 16 18 20 23 9...

  11. Methods for detecting nucleic acid sequences

    SciTech Connect

    Duck, P.; Bender, R.

    1991-04-30

    This patent describes a method for detecting a single-stranded target nucleic acid. It comprises: obtaining the single-stranded target nucleic acid; forming a reaction mixture which includes the target nucleic acid and a complementary single-stranded nucleic acid probe under conditions which allow the target nucleic acid and the probe to hybridize to each other and form a double-stranded, target-probe complex, the probe being present in molar excess relative to the target; treating the double-stranded, target-probe complex so as to cleave the probe within a predetermined sequence of the scissile nucleic acid linkage and thereby form at least one intact DNA-containing oligonucleotide fragment from the probe, such fragment being, or being treated so as to be, no longer capable of remaining hybridized to the target nucleic acid; detecting the intact DNA-containing fragments so formed and thereby detecting the single-stranded target nucleic acid.

  12. Novel preparation of chiral ?-amino acids using the Mitsunobu-Tsunoda reaction.

    PubMed

    Noisier, Anaïs F M; Harris, Craig S; Brimble, Margaret A

    2013-09-11

    An efficient synthesis of racemic or optically active ?-amino acids by modified-Mitsunobu alkylation of a racemic or chiral glycine template from alcohols was developed. Libraries of amino acids were prepared in moderate to good yield with good to high enantioselectivity. This simple method widens the scope for preparation of structurally diverse amino acids. PMID:23877629

  13. Reaction of Calcite and Dolomite with In-Situ Gelled Acids, Organic Acids, and Environmentally Friendly Chelating Agent (GLDA) 

    E-print Network

    Rabie, Ahmed 1978-

    2012-11-16

    )????????????????...???? 20 Fig. 2.6 Effect of Disk Rotational Speed on the Dissolution Rate of Pink Desert Limestone in 5 wt% In-situ Gelled HCl at 150oF, (Rabie et al. 2011a)???????????????????????...?? 21 Fig. 2.7 Core Flood Setup????????????...????????... 23 Fig. 3.1... of Calcium Concentration with Time for the Dolomite Reaction with 20, 25, 30, and 35 wt% GLDA at 1500 rpm and 250?F? 78 Fig. 5.1 A Schematic Diagram for the Rotating Disk Apparatus Used for Reaction Rate Measurements..??.??????????????. 89 Fig. 5...

  14. Unexpected racemization of proline or hydroxy-proline phenacyl ester during coupling reactions with Boc-amino acids.

    PubMed

    Kuroda, H; Kubo, S; Chino, N; Kimura, T; Sakakibara, S

    1992-08-01

    When L-proline or O-benzyl-trans-4-hydroxy-L-proline phenacyl ester was coupled with Boc-amino acids in dimethylformamide using water-soluble carbodiimide (WSCI) in the presence of anhydrous 1-hydroxybenzotriazole (HOBt) as coupling reagents, extensive racemization was observed at the C alpha of the proline or hydroxy-proline residue. The extent of racemization was measured by HPLC after the coupling with Boc-L-Leu-OH in the presence or absence of HOBt. The extent of racemization increased when HOBt was added to the reaction mixture, but greatly decreased when it was not, indicating that HOBt was needed for inducing racemization. Almost no racemization was observed when the coupling reaction was carried out by the mixed anhydride procedure in tetrahydrofuran or by the carbodiimide method in dichloromethane without using HOBt. In the case of coupling reactions with ordinary L-amino acid phenacyl esters, no racemization was observed. Examination of some model systems yielded sufficient evidence to prove that HOBt is an efficient catalyst for racemizing proline or hydroxy-proline phenacyl ester not only in the stage of cyclic intermediate formation but also in the opening of the ring structure. Thus, the racemization reaction was found to be closely related to the formation of the cyclic carbinol-amine derivative. PMID:1446968

  15. IN VITRO STUDIES ON LONGWAVE ULTRAVIOLET LIGHT-DEPENDENT REACTIONS OF THE SKIN PHOTOSENSITIZER CHLORPROMAZINE WITH NUCLEIC ACIDS, PURINES AND PYRIMIDINES

    Microsoft Academic Search

    Guinter Kahn; Barry P. Davis

    1970-01-01

    Fluorescence spectral shifts were observed when chlorpromazine was irradiated with long-wave ultraviolet light in the presence of nucleic acids. An increase in fluorescence was accompanied by incorporation of radioactivity from 3H-chlorpromazine into the alcohol-insoluble (nucleic acid) fraction of reaction mixtures. Apparent complex formation proceeded at a faster rate with single-stranded nucleic acids than with double-stranded nucleic acids. Spectral shifts also

  16. Structure and DNA Hybridization Properties of Mixed Nucleic Acid\\/Maleimide-Ethylene Glycol Monolayers

    Microsoft Academic Search

    Chi-Ying Lee; Phuong-Cac T. Nguyen; David W. Grainger; Lara J. Gamble; David G. Castner

    2007-01-01

    The surface structure and DNA hybridization performance of thiolated single-strand DNA (HS-ssDNA) covalently attached to a maleimide-ethylene glycol disulfide (MEG) monolayer on gold have been investigated. Monolayer immobilization chemistry and surface coverage of reactive ssDNA probes were studied by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. Orientation of the ssDNA probes was determined by near-edge X-ray absorption fine

  17. Self-assembly of nucleic acids, silk and hybrid materials thereof

    NASA Astrophysics Data System (ADS)

    Humenik, Martin; Scheibel, Thomas

    2014-12-01

    Top-down approaches based on etching techniques have almost reached their limits in terms of dimension. Therefore, novel assembly strategies and types of nanomaterials are required to allow technological advances. Self-assembly processes independent of external energy sources and unlimited in dimensional scaling have become a very promising approach. Here, we highlight recent developments in self-assembled DNA-polymer, silk-polymer and silk-DNA hybrids as promising materials with biotic and abiotic moieties for constructing complex hierarchical materials in ‘bottom-up’ approaches. DNA block copolymers assemble into nanostructures typically exposing a DNA corona which allows functionalization, labeling and higher levels of organization due to its specific addressable recognition properties. In contrast, self-assembly of natural silk proteins as well as their recombinant variants yields mechanically stable ?-sheet rich nanostructures. The combination of silk with abiotic polymers gains hybrid materials with new functionalities. Together, the precision of DNA hybridization and robustness of silk fibrillar structures combine in novel conjugates enable processing of higher-order structures with nanoscale architecture and programmable functions.

  18. Detection of nucleic acid hybridization via oxide-gated carbon nanotube field-effect transistors

    NASA Astrophysics Data System (ADS)

    Aschenbach, Konrad H.; Pandana, Herman; Lee, Jookyung; Khan, Javed; Fuhrer, Michael; Lenski, Dan; Gomez, R. D.

    2008-04-01

    A label-free DNA hybridization detector using carbon nanotube transistor arrays is developed. The sensors are comprised of a network of carbon nanotubes covered by thin oxide layer, which serve as efficient charge transducers for biomolecules in solution. Probe DNA sequences are immobilized on the gate oxide, and the conductance is measured before and after exposure and hybridization with a target DNA. Complementary binding results in a net charge doubling at the oxide surface which induces a positive shift in the threshold voltage and concomitant increase in the current at fixed bias. The method does not involve chemical functionalization of the carbon nanotubes and is compatible with protocols in conventional DNA microarrays. Most importantly, the technique does not require reporter molecules or tagging labels, which greatly simplifies the operation and reduces the cost. We have shown a measurable response to hybridization with target concentration of ~1 nM. The implementation, theory of operation, device fabrication and solutions to pertinent engineering issues to build practical system are discussed.

  19. Kinetics study of heterogeneous reactions of ozone with erucic acid using an ATR-IR flow reactor.

    PubMed

    Leng, Chunbo; Hiltner, Joseph; Pham, Hai; Kelley, Judas; Mach, Mindy; Zhang, Yunhong; Liu, Yong

    2014-03-01

    The ozone initiated heterogeneous oxidation of erucic acid (EA) thin film was investigated using a flow system combined with attenuated total reflection infrared spectroscopy (ATR-IR) over wide ranges of ozone concentrations (0.25-60 ppm), thin film thickness (0.1-1.0 ?m), temperatures (263-298 K), and relative humidities (0-80% RH) for the first time. Pseudo-first-order rate constants, kapp, and overall reactive uptake coefficients, ?, were obtained through changes in the absorbance of C[double bond, length as m-dash]O stretching bands at 1695 cm(-1), which is assigned to the carbonyl group in carboxylic acid. Results showed that the reaction followed the Langmuir-Hinshelwood mechanism and kapp was largely dominated by surface reaction over bulk phase reaction. In addition, both the kapp and the ? values showed very strong temperature dependences (?two orders of magnitude) over the temperature range; in contrast, they only slightly increased with increasing RH values from 0-80%. According to the kapp values as a function of temperature, the activation energy for the heterogeneous reaction was estimated to be 80.6 kJ mol(-1). Our results have suggested that heterogeneous reactions between ozone and unsaturated solid surfaces likely have a substantially greater temperature dependence than liquid ones. Moreover, the hygroscopic properties of EA thin films before and after exposure to ozone were also studied by measurement of water uptake. Based on the hygroscopicity data, the insignificant RH effect on reaction kinetics was probably due to the relatively weak water uptake by the unreacted and reacted EA thin films. PMID:24457621

  20. Rapid Identification of Staphylococcus aureus in Blood Cultures by a Combination of Fluorescence In Situ Hybridization Using Peptide Nucleic Acid Probes and Flow Cytometry

    Microsoft Academic Search

    Hanna Hartmann; Henrik Stender; Andrea Schafer; Ingo B. Autenrieth; Volkhard A. J. Kempf

    2005-01-01

    Fluorescence in situ hybridization (FISH) using peptide nucleic acid probes (PNAs) allows the identification of Staphylococcus aureus from human blood culture samples. We present data revealing that the combination of PNA FISH and flow cytometry is a possible approach for the noncultural identification of staphylococci in blood cultures.