Science.gov

Sample records for acid hybridization reactions

  1. Heteropoly Acid/Nitrogen Functionalized Onion-like Carbon Hybrid Catalyst for Ester Hydrolysis Reactions.

    PubMed

    Liu, Wei; Qi, Wei; Guo, Xiaoling; Su, Dangsheng

    2016-02-01

    A novel heteropoly acid (HPA)/nitrogen functionalized onion-like carbon (NOLC) hybrid catalyst was synthesized through supramolecular (electrostatic and hydrogen bond) interactions between the two components. The chemical structure and acid strength of the HPA/NOLC hybrid have been fully characterized by thermogravimetric analysis, IR spectroscopy, X-ray photoelectron spectroscopy, NH3 temperature-programmed desorption and acid-base titration measurements. The proposed method for the fabrication of the HPA/NOLC hybrid catalyst is a universal strategy for different types of HPAs to meet various requirements of acidic or redox catalysis. The hydrophobic environment of NOLC effectively prevents the deactivation of HPA in an aqueous system, and the combination of uniformly dispersed HPA clusters and the synergistic effect between NOLC and HPA significantly promotes its activity in ester hydrolysis reactions, which is higher than that of bare PWA as homogeneous catalyst. The kinetics of the hydrolysis reactions indicate that the aggregation status of the catalyst particles has great influence on the apparent activity. PMID:26606266

  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. Direct RNA detection without nucleic acid purification and PCR: Combining sandwich hybridization with signal amplification based on branched hybridization chain reaction.

    PubMed

    Xu, Yao; Zheng, Zhi

    2016-05-15

    We have developed a convenient, robust and low-cost RNA detection system suitable for high-throughput applications. This system uses a highly specific sandwich hybridization to capture target RNA directly onto solid support, followed by on-site signal amplification via 2-dimensional, branched hybridizing chain polymerization through toehold-mediated strand displacement reaction. The assay uses SYBR Green to detect targets at concentrations as low as 1pM, without involving nucleic acid purification or any enzymatic reaction, using ordinary oligonucleotides without modification or labeling. The system was demonstrated in the detection of malaria RNA in blood and GAPDH gene expression in cell lysate. PMID:26761615

  4. 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

  5. Base-acid hybrid water electrolysis.

    PubMed

    Chen, Long; Dong, Xiaoli; Wang, Fei; Wang, Yonggang; Xia, Yongyao

    2016-02-11

    A base-acid hybrid electrolytic system with a low onset voltage of 0.78 V for water electrolysis was developed by using a ceramic Li-ion exchange membrane to separate the oxygen-evolving reaction (OER) in a basic electrolyte solution containing the Li-ion and hydrogen-evolving reaction (HER) in an acidic electrolyte solution. PMID:26804323

  6. One-Step Detection of c-kit Point Mutations Using Peptide Nucleic Acid-Mediated Polymerase Chain Reaction Clamping and Hybridization Probes

    PubMed Central

    Sotlar, Karl; Escribano, Luis; Landt, Olfert; Möhrle, Stefanie; Herrero, Sonia; Torrelo, Antonio; Lass, Ulrich; Horny, Hans-Peter; Bültmann, Burkhard

    2003-01-01

    The prognostic significance of somatic activating codon 816 c-kit mutations in pediatric urticaria pigmentosa has not yet been established in detail. Detection of such mutations in archival paraffin-embedded biopsies is usually hampered by an abundance of surrounding normal cells. Here we describe a method for the selective amplification and specific detection of c-kit mutation Asp816→Val in complete tissue sections cut from up to 24-year-old paraffin blocks. Peptide nucleic acid-mediated polymerase chain reaction clamping of the wild-type allele was combined with on-line mutation detection using oligonucleotide hybridization probes. In DNA extracted from HMC-1 cells heterozygously carrying the c-kit mutation Asp816→Val, the one-tube assay allowed specific detection of this mutation in a more than 1000-fold excess of normal background DNA within 1 hour and without the need for additional analytical steps. In a series of 38 cases with pediatric urticaria pigmentosa we detected c-kit codons 815 and 816 mutations in 16 cases. Mutation detection did not correlate with clinical outcome after a mean follow-up of 11.2 years. In conclusion, the procedure described may represent an ideal screening tool for all kinds of clinical applications, using point mutations as markers of, for example, early events in carcinogenesis, circulating metastatic tumor cells, and minimal residual disease. PMID:12598308

  7. One-step detection of c-kit point mutations using peptide nucleic acid-mediated polymerase chain reaction clamping and hybridization probes.

    PubMed

    Sotlar, Karl; Escribano, Luis; Landt, Olfert; Möhrle, Stefanie; Herrero, Sonia; Torrelo, Antonio; Lass, Ulrich; Horny, Hans-Peter; Bültmann, Burkhard

    2003-03-01

    The prognostic significance of somatic activating codon 816 c-kit mutations in pediatric urticaria pigmentosa has not yet been established in detail. Detection of such mutations in archival paraffin-embedded biopsies is usually hampered by an abundance of surrounding normal cells. Here we describe a method for the selective amplification and specific detection of c-kit mutation Asp816-->Val in complete tissue sections cut from up to 24-year-old paraffin blocks. Peptide nucleic acid-mediated polymerase chain reaction clamping of the wild-type allele was combined with on-line mutation detection using oligonucleotide hybridization probes. In DNA extracted from HMC-1 cells heterozygously carrying the c-kit mutation Asp816-->Val, the one-tube assay allowed specific detection of this mutation in a more than 1000-fold excess of normal background DNA within 1 hour and without the need for additional analytical steps. In a series of 38 cases with pediatric urticaria pigmentosa we detected c-kit codons 815 and 816 mutations in 16 cases. Mutation detection did not correlate with clinical outcome after a mean follow-up of 11.2 years. In conclusion, the procedure described may represent an ideal screening tool for all kinds of clinical applications, using point mutations as markers of, for example, early events in carcinogenesis, circulating metastatic tumor cells, and minimal residual disease. PMID:12598308

  8. Nucleic acid in-situ hybridization detection of infectious agents

    NASA Astrophysics Data System (ADS)

    Thompson, Curtis T.

    2000-04-01

    Limitations of traditional culture methods and newer polymerase chain reaction (PCR)-based methods for detection and speciation of infectious agents demonstrate the need for more rapid and better diagnostics. Nucleic acid hybridization is a detection technology that has gained wide acceptance in cancer and prenatal cytogenetics. Using a modification of the nucleic acid hybridization technique known as fluorescence in-situ hybridization, infectious agents can be detected in a variety of specimens with high sensitivity and specificity. The specimens derive from all types of human and animal sources including body fluids, tissue aspirates and biopsy material. Nucleic acid hybridization can be performed in less than one hour. The result can be interpreted either using traditional fluorescence microscopy or automated platforms such as micro arrays. This paper demonstrates proof of concept for nucleic acid hybridization detection of different infectious agents. Interpretation within a cytologic and histologic context is possible with fluorescence microscopic analysis, thereby providing confirmatory evidence of hybridization. With careful probe selection, nucleic acid hybridization promises to be a highly sensitive and specific practical diagnostic alternative to culture, traditional staining methods, immunohistochemistry and complicated nucleic acid amplification tests.

  9. Electric field directed nucleic acid hybridization on microchips.

    PubMed Central

    Edman, C F; Raymond, D E; Wu, D J; Tu, E; Sosnowski, R G; Butler, W F; Nerenberg, M; Heller, M J

    1997-01-01

    Selection and adjustment of proper physical parameters enables rapid DNA transport, site selective concentration, and accelerated hybridization reactions to be carried out on active microelectronic arrays. These physical parameters include DC current, voltage, solution conductivity and buffer species. Generally, at any given current and voltage level, the transport or mobility of DNA is inversely proportional to electrolyte or buffer conductivity. However, only a subset of buffer species produce both rapid transport, site specific concentration and accelerated hybridization. These buffers include zwitterionic and low conductivity species such as: d- and l-histidine; 1- and 3-methylhistidines; carnosine; imidazole; pyridine; and collidine. In contrast, buffers such as glycine, beta-alanine and gamma-amino-butyric acid (GABA) produce rapid transport and site selective concentration but do not facilitate hybridization. Our results suggest that the ability of these buffers (histidine, etc.) to facilitate hybridization appears linked to their ability to provide electric field concentration of DNA; to buffer acidic conditions present at the anode; and in this process acquire a net positive charge which then shields or diminishes repulsion between the DNA strands, thus promoting hybridization. PMID:9396795

  10. Gene identification by chromosomal in-situ hybridization, microdissection and polymerase chain reaction amplification.

    PubMed

    Sallie, R

    1996-06-01

    This paper describes a theoretical method by which candidate genes for inherited diseases can be identified by polymerase chain reaction amplification and subsequent cloning of organ-specific complementary deoxyribonucleic acid libraries hybridized in situ to, and subsequently dissected from, the cognate chromosome. A specific application of this technique to isolate genes related to genetic haemochromatosis is outlined. PMID:8803937

  11. 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...

  12. Gold nanoparticles-graphene hybrids as active catalysts for Suzuki reaction

    SciTech Connect

    Li, Yang; Fan, Xiaobin; Qi, Junjie; Ji, Junyi; Wang, Shulan; Zhang, Guoliang; Zhang, Fengbao

    2010-10-15

    Graphene was successfully modified with gold nanoparticles in a facile route by reducing chloroauric acid in the presence of sodium dodecyl sulfate, which is used as both a surfactant and reducing agent. The gold nanoparticles-graphene hybrids were characterized by high-resolution transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction and energy X-ray spectroscopy. We demonstrate for the first time that the gold nanoparticles-graphene hybrids can act as efficient catalysts for the Suzuki reaction in water under aerobic conditions. The catalytic activity of gold nanoparticles-graphene hybrids was influenced by the size of the gold nanoparticles.

  13. A Lewis acid-promoted Pinner reaction

    PubMed Central

    Pfaff, Dominik; Nemecek, Gregor

    2013-01-01

    Summary Carbonitriles and alcohols react in a Lewis acid-promoted Pinner reaction to carboxylic esters. Best results are obtained with two equivalents of trimethylsilyl triflate as Lewis acid. Good yields are achieved with primary alcohols and aliphatic or benzylic carbonitriles, but the straightforward synthesis of acrylates and benzoates starting with acrylonitrile and benzonitrile, respectively, is similarly possible. Phenols are not acylated under these reaction conditions. The method has been used for the first total synthesis of the natural product monaspilosin. In the reaction of benzyl alcohols variable amounts of amides are formed in a Ritter-type side reaction. PMID:23946857

  14. Design and Synthesis of Novel Isoxazole Tethered Quinone-Amino Acid Hybrids

    PubMed Central

    Ravi Kumar, P.; Sambaiah, M.; Kandula, Venu; Payili, Nagaraju; Jaya Shree, A.; Yennam, Satyanarayana

    2014-01-01

    A new series of isoxazole tethered quinone-amino acid hybrids has been designed and synthesized involving 1,3-dipolar cycloaddition reaction followed by an oxidation reaction using cerium ammonium nitrate (CAN). Using this method, for the first time various isoxazole tethered quinone-phenyl alanine and quinone-alanine hybrids were synthesized from simple commercially available 4-bromobenzyl bromide, propargyl bromide, and 2,5-dimethoxybenzaldehyde in good yield. PMID:25709839

  15. 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.

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

    DOEpatents

    Fodor, Stephen P. A.; Lipshutz, Robert J.; Huang, Xiaohua

    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.

  17. Hybrid Simulations of Reaction-Diffusion Systems in Porous Media

    SciTech Connect

    Tartakovsky, Alexandre M.; Tartakovsky, Daniel M.; Scheibe, Timothy D.; Meakin, Paul

    2008-10-13

    Hybrid or multi-physics algorithms provide an efficient computational tool for combining micro- and macro-scale descriptions of a physical phenomenon. Their use becomes imperative when micro-scale descriptions are too computationally expensive to be conducted in the whole domain and macro-scale descriptions fail in a small portion of the computation domain. We present a hybrid algorithm to model a general class of reaction-diffusion processes in granular porous media, which includes mixing-induced mineral precipitation on or dissolution of the porous matrix that cannot be accurately described with a continuum (Darcy-scale) model. The pore-scale/Darcy-scale hybrid is constructed by coupling a solution of the reaction-diffusion equation (RDE) at the pore-scale with a continuum Darcy-level solution of theaveraged RDE. The resulting pore-Darcy scales hybrid is solved numerically by employing a multi-resolution meshless discretization based on Smoothed Particle Hydrodynamics (SPH) method, which ensures the seamless, non-iterative coupling of the two components of the hybrid. The presented computational examples illustrate the accuracy and efficiency of the proposed hybrid model.

  18. Hybrid discrete/continuum algorithms for stochastic reaction networks

    SciTech Connect

    Safta, Cosmin Sargsyan, Khachik Debusschere, Bert Najm, Habib N.

    2015-01-15

    Direct solutions of the Chemical Master Equation (CME) governing Stochastic Reaction Networks (SRNs) are generally prohibitively expensive due to excessive numbers of possible discrete states in such systems. To enhance computational efficiency we develop a hybrid approach where the evolution of states with low molecule counts is treated with the discrete CME model while that of states with large molecule counts is modeled by the continuum Fokker–Planck equation. The Fokker–Planck equation is discretized using a 2nd order finite volume approach with appropriate treatment of flux components. The numerical construction at the interface between the discrete and continuum regions implements the transfer of probability reaction by reaction according to the stoichiometry of the system. The performance of this novel hybrid approach is explored for a two-species circadian model with computational efficiency gains of about one order of magnitude.

  19. Hybrid discrete/continuum algorithms for stochastic reaction networks

    DOE PAGESBeta

    Safta, Cosmin; Sargsyan, Khachik; Debusschere, Bert; Najm, Habib N.

    2014-10-22

    Direct solutions of the Chemical Master Equation (CME) governing Stochastic Reaction Networks (SRNs) are generally prohibitively expensive due to excessive numbers of possible discrete states in such systems. To enhance computational efficiency we develop a hybrid approach where the evolution of states with low molecule counts is treated with the discrete CME model while that of states with large molecule counts is modeled by the continuum Fokker-Planck equation. The Fokker-Planck equation is discretized using a 2nd order finite volume approach with appropriate treatment of flux components to avoid negative probability values. The numerical construction at the interface between the discretemore » and continuum regions implements the transfer of probability reaction by reaction according to the stoichiometry of the system. As a result, the performance of this novel hybrid approach is explored for a two-species circadian model with computational efficiency gains of about one order of magnitude.« less

  20. Hybrid discrete/continuum algorithms for stochastic reaction networks

    SciTech Connect

    Safta, Cosmin; Sargsyan, Khachik; Debusschere, Bert; Najm, Habib N.

    2014-10-22

    Direct solutions of the Chemical Master Equation (CME) governing Stochastic Reaction Networks (SRNs) are generally prohibitively expensive due to excessive numbers of possible discrete states in such systems. To enhance computational efficiency we develop a hybrid approach where the evolution of states with low molecule counts is treated with the discrete CME model while that of states with large molecule counts is modeled by the continuum Fokker-Planck equation. The Fokker-Planck equation is discretized using a 2nd order finite volume approach with appropriate treatment of flux components to avoid negative probability values. The numerical construction at the interface between the discrete and continuum regions implements the transfer of probability reaction by reaction according to the stoichiometry of the system. As a result, the performance of this novel hybrid approach is explored for a two-species circadian model with computational efficiency gains of about one order of magnitude.

  1. Continuously tunable nucleic acid hybridization probes.

    PubMed

    Wu, Lucia R; Wang, Juexiao Sherry; Fang, John Z; R Evans, Emily; Pinto, Alessandro; Pekker, Irena; Boykin, Richard; Ngouenet, Celine; Webster, Philippa J; Beechem, Joseph; Zhang, David Yu

    2015-12-01

    In silico-designed nucleic acid probes and primers often do not achieve favorable specificity and sensitivity tradeoffs on the first try, and iterative empirical sequence-based optimization is needed, particularly in multiplexed assays. We present a novel, on-the-fly method of tuning probe affinity and selectivity by adjusting the stoichiometry of auxiliary species, which allows for independent and decoupled adjustment of the hybridization yield for different probes in multiplexed assays. Using this method, we achieved near-continuous tuning of probe effective free energy. To demonstrate our approach, we enforced uniform capture efficiency of 31 DNA molecules (GC content, 0-100%), maximized the signal difference for 11 pairs of single-nucleotide variants and performed tunable hybrid capture of mRNA from total RNA. Using the Nanostring nCounter platform, we applied stoichiometric tuning to simultaneously adjust yields for a 24-plex assay, and we show multiplexed quantitation of RNA sequences and variants from formalin-fixed, paraffin-embedded samples. PMID:26480474

  2. A DNA origami nanorobot controlled by nucleic acid hybridization.

    PubMed

    Torelli, Emanuela; Marini, Monica; Palmano, Sabrina; Piantanida, Luca; Polano, Cesare; Scarpellini, Alice; Lazzarino, Marco; Firrao, Giuseppe

    2014-07-23

    A prototype for a DNA origami nanorobot is designed, produced, and tested. The cylindrical nanorobot (diameter of 14 nm and length of 48 nm) with a switchable flap, is able to respond to an external stimulus and reacts by a physical switch from a disarmed to an armed configuration able to deliver a cellular compatible message. In the tested design the robot weapon is a nucleic acid fully contained in the inner of the tube and linked to a single point of the internal face of the flap. Upon actuation the nanorobot moves the flap extracting the nucleic acid that assembles into a hemin/G-quadruplex horseradish peroxidase mimicking DNAzyme catalyzing a colorimetric reaction or chemiluminescence generation. The actuation switch is triggered by an external nucleic acid (target) that interacts with a complementary nucleic acid that is beard externally by the nanorobot (probe). Hybridization of probe and target produces a localized structural change that results in flap opening. The flap movement is studied on a two-dimensional prototype origami using Förster resonance energy transfer and is shown to be triggered by a variety of targets, including natural RNAs. The nanorobot has potential for in vivo biosensing and intelligent delivery of biological activators. PMID:24648163

  3. 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

  4. Reactions of tetraphenyltitanium with organic acids

    SciTech Connect

    Razuvaev, G.A.; Vyshinskaya, L.I.; Vasil'eva, G.A.

    1987-12-10

    As a result of the reactions of tetraphenyltitanium with dibasic organic acids high yields were obtained of new thermally stable titanium(III) complexes: phenyltitanium(III)carboxylates. Under the action of proton-active reagents (hydrochloric acid, cyclopentadiene, methanol) the latter break down with the breakage of titanium-phenyl bond. The proposed structure was based on IR- and ESR-spectral data. The dinuclear structure of the complexes was established on the basis of a study of the triplet structure of the ESR spectra, which showed the existence of intermolecular titanium-titanium exchange through methylene groups of the dicarboxylate bridges.

  5. Hybrid multiscale simulation of a mixing-controlled reaction

    SciTech Connect

    Scheibe, Timothy D.; Schuchardt, Karen L.; Agarwal, Khushbu; Chase, Jared M.; Yang, Xiaofan; Palmer, Bruce J.; Tartakovsky, Alexandre M.; Elsethagen, Todd O.; Redden, George D.

    2015-09-01

    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. Since the location and number of pore-scale model regions in the model varies as the reactions proceed, an adaptive script defines the number and location of pore regions within each continuum iteration and initializes pore-scale simulations from macroscale information. Another script communicates information from the pore-scale simulation results back to the continuum scale. These components provide loose coupling between the pore- and continuum-scale codes into a single hybrid multiscale model implemented within the SWIFT workflow environment. In this paper, we consider an irreversible homogenous bimolecular reaction (two solutes reacting to form a third solute) in a 2D test problem. This paper 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.

  6. Adaptive hybrid simulations for multiscale stochastic reaction networks

    SciTech Connect

    Hepp, Benjamin; Gupta, Ankit; Khammash, Mustafa

    2015-01-21

    The probability distribution describing the state of a Stochastic Reaction Network (SRN) evolves according to the Chemical Master Equation (CME). It is common to estimate its solution using Monte Carlo methods such as the Stochastic Simulation Algorithm (SSA). In many cases, these simulations can take an impractical amount of computational time. Therefore, many methods have been developed that approximate sample paths of the underlying stochastic process and estimate the solution of the CME. A prominent class of these methods include hybrid methods that partition the set of species and the set of reactions into discrete and continuous subsets. Such a partition separates the dynamics into a discrete and a continuous part. Simulating such a stochastic process can be computationally much easier than simulating the exact discrete stochastic process with SSA. Moreover, the quasi-stationary assumption to approximate the dynamics of fast subnetworks can be applied for certain classes of networks. However, as the dynamics of a SRN evolves, these partitions may have to be adapted during the simulation. We develop a hybrid method that approximates the solution of a CME by automatically partitioning the reactions and species sets into discrete and continuous components and applying the quasi-stationary assumption on identifiable fast subnetworks. Our method does not require any user intervention and it adapts to exploit the changing timescale separation between reactions and/or changing magnitudes of copy-numbers of constituent species. We demonstrate the efficiency of the proposed method by considering examples from systems biology and showing that very good approximations to the exact probability distributions can be achieved in significantly less computational time. This is especially the case for systems with oscillatory dynamics, where the system dynamics change considerably throughout the time-period of interest.

  7. Hybrid stochastic simulations of intracellular reaction-diffusion systems

    PubMed Central

    Kalantzis, Georgios

    2009-01-01

    With the observation that stochasticity is important in biological systems, chemical kinetics have begun to receive wider interest. While the use of Monte Carlo discrete event simulations most accurately capture the variability of molecular species, they become computationally costly for complex reaction-diffusion systems with large populations of molecules. On the other hand, continuous time models are computationally efficient but they fail to capture any variability in the molecular species. In this study a novel hybrid stochastic approach is introduced for simulating reaction-diffusion systems. We developed a dynamic partitioning strategy using fractional propensities. In that way processes with high frequency are simulated mostly with deterministic rate-based equations, and those with low frequency mostly with the exact stochastic algorithm of Gillespie. In this way we preserve the stochastic behavior of cellular pathways while being able to apply it to large populations of molecules. In this article we describe this hybrid algorithmic approach, and we demonstrate its accuracy and efficiency compared with the Gillespie algorithm for two different systems. First, a model of intracellular viral kinetics with two steady states and second, a compartmental model of the postsynaptic spine head for studying the dynamics of Ca+2 and NMDA receptors. PMID:19414282

  8. Hybride magnetic nanostructure based on amino acids functionalized polypyrrole

    NASA Astrophysics Data System (ADS)

    Nan, Alexandrina; Bunge, Alexander; Turcu, Rodica

    2015-12-01

    Conducting polypyrrole is especially promising for many commercial applications because of its unique optical, electric, thermal and mechanical properties. We report the synthesis and characterization of novel pyrrole functionalized monomers and core-shell hybrid nanostructures, consisting of a conjugated polymer layer (amino acids functionalized pyrrole copolymers) and a magnetic nanoparticle core. For functionalization of the pyrrole monomer we used several amino acids: tryptophan, leucine, phenylalanine, serine and tyrosine. These amino acids were linked via different types of hydrophobic linkers to the nitrogen atom of the pyrrole monomer. The magnetic core-shell hybrid nanostructures are characterized by various methods such as FTIR spectroscopy, transmission electron microscopy (TEM) and magnetic measurements.

  9. Hybrid isolation of micro vibrations induced by reaction wheels

    NASA Astrophysics Data System (ADS)

    Lee, Dae-Oen; Park, Geeyong; Han, Jae-Hung

    2016-02-01

    As the technology for precision satellite payloads continues to advance, the requirements for the pointing stability of the satellites are becoming extremely high. In many situations, even small amplitude disturbances generated by the onboard components may cause serious degradation in the performance of high precision payloads. In such situations, vibration isolators can be installed to reduce the vibration transmission. In this work, a hybrid vibration isolator comprising passive and active components is proposed to provide an effective solution to the vibration problems caused by the reaction wheel disturbances. Firstly, mathematical modeling and experimental study of a single axis vibration isolator having high damping and high roll-off rate for the high frequency region and active components that enhance isolation performance for narrow frequency bands are presented. This concept is then extended to multi-axis by forming Stewart platform and the performance is experimentally verified. The tests on a flexible testbed show effective vibration isolation by the proposed vibration isolator.

  10. 40 CFR 721.10125 - Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    .... (1) The chemical substances identified generically as alkenedioic acid, dialkyl ester, reaction..., reaction products with polyaminocarbomonocycle and alkenoic acid alkyl ester (generic). 721.10125 Section... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific...

  11. 40 CFR 721.10125 - Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    .... (1) The chemical substances identified generically as alkenedioic acid, dialkyl ester, reaction..., reaction products with polyaminocarbomonocycle and alkenoic acid alkyl ester (generic). 721.10125 Section... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific...

  12. 40 CFR 721.10125 - Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    .... (1) The chemical substances identified generically as alkenedioic acid, dialkyl ester, reaction..., reaction products with polyaminocarbomonocycle and alkenoic acid alkyl ester (generic). 721.10125 Section... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific...

  13. 40 CFR 721.10125 - Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    .... (1) The chemical substances identified generically as alkenedioic acid, dialkyl ester, reaction..., reaction products with polyaminocarbomonocycle and alkenoic acid alkyl ester (generic). 721.10125 Section... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific...

  14. 40 CFR 721.10125 - Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    .... (1) The chemical substances identified generically as alkenedioic acid, dialkyl ester, reaction..., reaction products with polyaminocarbomonocycle and alkenoic acid alkyl ester (generic). 721.10125 Section... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific...

  15. Novel hybrid DHPM-fatty acids: synthesis and activity against glioma cell growth in vitro.

    PubMed

    Treptow, Tamara G M; Figueiró, Fabrício; Jandrey, Elisa H F; Battastini, Ana M O; Salbego, Christianne G; Hoppe, Juliana B; Taborda, Priscila S; Rosa, Sabrina B; Piovesan, Luciana A; Montes D'Oca, Caroline Da R; Russowsky, Dennis; Montes D'Oca, Marcelo G

    2015-05-01

    We described the first synthesis of fatty acid 3,4-dihydropyrimidinones (DHPM-fatty acids) using the Biginelli multicomponent reaction. Antiproliferative activity on two glioma cell lines (C6 rat and U-138-MG human) was also reported. The novel DHPM-fatty acids reduced glioma cell viability relative to temozolomide. Hybrid oxo-monastrol-palmitic acid was the most potent, reducing U-138-MG human cell viability by ca. 50% at 10 μM. In addition, the DHPM-fatty acids showed a large safety range to neural cells, represented by the organotypic hippocampal culture. These results suggest that the increased lipophilicity of DHPM-fatty acids offer a promising approach to overcoming resistance to chemotherapy and may play an important role in the development of new antitumor drugs. PMID:25863023

  16. Magnetite-supported sulfonic acid: a retrievable nanocatalyst for the Ritter reaction and multicomponent reactions

    EPA Science Inventory

    Magnetite-sulfonic acid (NanocatFe-OSO3H), prepared by wet-impregnation method, serves as a magnetically retrievable sustainable catalyst for the Ritter reaction which can be used in several reaction cycles without any loss of activity.

  17. 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.

  18. Sequential Mukaiyama-Michael reaction induced by carbon acids.

    PubMed

    Yanai, Hikaru; Kobayashi, Osamu; Takada, Kenji; Isono, Takuya; Satoh, Toshifumi; Matsumoto, Takashi

    2016-02-16

    In the presence of a strong carbon acid, the sequential Mukaiyama-Michael reaction using two different Michael acceptors proceeded and the reaction of ketene silyl acetal derived from EtOAc with α-pyrones as primal acceptors yielded the corresponding cyclic ketene silyl acetals, which were reactive enough to undergo the following reaction with second acceptors. PMID:26734829

  19. 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 β-cyclodextrin on the oxidation pathway was another object of this study. It is shown that β-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 β-cyclodextrin concentration.

  20. Natural cinnamic acids, synthetic derivatives and hybrids with antimicrobial activity.

    PubMed

    Guzman, Juan David

    2014-01-01

    Antimicrobial natural preparations involving cinnamon, storax and propolis have been long used topically for treating infections. Cinnamic acids and related molecules are partly responsible for the therapeutic effects observed in these preparations. Most of the cinnamic acids, their esters, amides, aldehydes and alcohols, show significant growth inhibition against one or several bacterial and fungal species. Of particular interest is the potent antitubercular activity observed for some of these cinnamic derivatives, which may be amenable as future drugs for treating tuberculosis. This review intends to summarize the literature data on the antimicrobial activity of the natural cinnamic acids and related derivatives. In addition, selected hybrids between cinnamic acids and biologically active scaffolds with antimicrobial activity were also included. A comprehensive literature search was performed collating the minimum inhibitory concentration (MIC) of each cinnamic acid or derivative against the reported microorganisms. The MIC data allows the relative comparison between series of molecules and the derivation of structure-activity relationships. PMID:25429559

  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

    ... alkylstannylene ester, reaction products with inorganic acid tetra alkyl ester (generic). 721.10679 Section 721... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10679 Carboxylic acid, substituted alkylstannylene ester, reaction products with inorganic acid tetra alkyl...

  2. Deoxyribonucleic acid–ribonucleic acid hybridization. Annealing and quantitative recovery of intact ribosomal ribonucleic acid molecules from hybrids

    PubMed Central

    Fry, Michael; Artman, Michael

    1969-01-01

    A simple and efficient method for hybridization and subsequent recovery of non-fragmented ribosomal RNA from the hybrid is described. The procedure involves annealing of immobilized denatured DNA bound on cellulose nitrate membrane filters to complementary RNA in 50% (v/v) formamide–0·33m-potassium chloride–10mm-tris–hydrochloric acid buffer, pH7·4, at 33° for 3hr. Under these conditions no detectable changes in the sedimentation coefficients of the input RNA were detected. The RNA can subsequently be recovered quantitatively from the hybrid in intact form by incubating the filters in formamide or in 85% (v/v) dimethyl sulphoxide. The applicability of the method for the evaluation of the absolute size of ribosomal RNA cistrons in Escherichia coli DNA and for the determination of the size of messenger RNA molecules is discussed. PMID:4907881

  3. Imino Acids in the Murchison Meteorite: Evidence of Strecker Reactions

    NASA Technical Reports Server (NTRS)

    Lerner, N. R.; Cooper, G. W.

    2003-01-01

    Both alpha-amino acids and alpha-hydroxy acids occur in aqueous extracts of the Murchison carbonaceous meteorite. The Strecker-cyanohydrin reaction, the reaction of carbonyl compounds, cyanide, and ammonia to produce amino and hydroxy acids, has been proposed as a source of such organic acids in meteorites. Such syntheses are consistent with the suggestion that interstellar precursors of meteoritic organic compounds accreted on the meteorite parent body together with other ices. Subsequent internal heating of the parent body melted these ices and led to the formation of larger compounds in synthetic reactions during aqueous alteration, which probably occurred at temperatures between 273K and 298K. In the laboratory, imino acids are observed as important by-products of the Strecker synthesis.

  4. "Extreme" Ugi reactions with some complex α-amino acids.

    PubMed

    Turner, Charles Dylan; Ciufolini, Marco A

    2012-09-21

    The Ti(IV)-catalyzed Ugi condensation of α-amino acids with electron-rich aromatic aldehydes performs adequately even with sterically demanding α-amino carboxylate salts. The reaction occurs diastereoselectively, in some cases with virtually complete diastereoselectivity. A stereochemical rationale for the reaction is proposed. PMID:22954286

  5. p-Aminophenylacetic acid-mediated synthesis of monodispersed titanium oxide hybrid microspheres in ethanol solution.

    PubMed

    Zhang, Hongye; Xie, Yun; Liu, Zhimin; Tao, Ranting; Sun, Zhenyu; Ding, Kunlun; An, Guimin

    2009-10-15

    Monodispersed TiO2 hybrid microspheres were prepared via the hydrolysis of titanium isopropoxide (TTIP) in ethanol solution containing p-aminophenylacetic acid (APA). The effects of the APA:TTIP molar ratio, water content, reaction time and reaction temperature on the morphology of the resultant spheres were investigated. The products were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction. It was demonstrated that the diameters of the resultant TiO2 spheres could be tuned in the range of 380-800 nm by changing the APA:TTIP molar ratio (1:3 to 3:1) and water content (1-3 v/v%) in the reaction medium, and that increasing the APA:TTIP molar ratio led to larger TiO2 hybrid spheres while increasing the water content decreased their size. The loading content of APA in the hybrid spheres could reach 20 wt.% as they were prepared with the APA:TTIP ratio of 3:1. The possible formation mechanism of the hybrid spheres was also investigated. It was found that APA slowed down the hydrolysis rate of the titanium precursor so that resulted in the formation of the TiO2 spheres. In addition, the APA present in TiO2 spheres acted as a reducing agent to in situ convert HAuCl4 into metallic Au on the surface of the TiO2 spheres. The catalytic activity of the resultant Au/APA-TiO2 composite was examined using transfer hydrogenation of phenylacetone with 2-propanol, and it was indicated that the catalyst displayed high efficiency for this reaction. PMID:19616218

  6. Spectrophotometric reaction rate method for determination of barbituric acid by inhibition of the hydrochloric acid-bromate reaction

    NASA Astrophysics Data System (ADS)

    Ensafi, Ali A.; Movahedinia, H.

    2003-11-01

    A new kinetic-spectrophotometric method was developed for the determination of barbituric acid. The method is based on its inhibition effect on the reaction between hydrochloric acid and bromate. The decolorization of methyl orange by the reaction products was used to monitor the reaction spectrophotometrically at 510 nm. The variable affecting the rate of the reaction was investigated. The method is simple, rapid, relatively sensitive and precise. The limit of detection is 7.9×10 -7 M and calibration rang is 1×10 -6-6.0×10 -4 M barbituric acid. The linearity range of the calibration graph is depends on bromate concentration. The relative standard deviation of seven replication determination of 5.6×10 -6 M barbituric acid was 1.8%. The influence of potential interfering substance was studied.

  7. Synthesis and conformational analysis of hybrid α/β-dipeptides incorporating S-glycosyl-β(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 α-amino acid attached to a quaternary glyco-β-amino acid. In particular, we combined a S-glycosylated β(2,2)-amino acid and two different types of α-amino acid, namely, aliphatic (alanine) and aromatic (phenylalanine and tryptophan) in the sequence of hybrid α/β-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-β-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 β-amino acid induced θ torsional angles close to 180° (anti). Notably, this value changed to 60° (gauche) when the peptidic sequence displayed aromatic α-amino acids due to the presence of CH-π interactions between the phenyl or indole ring and the methyl groups of the β-amino acid unit. PMID:25413453

  8. 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.

  9. Novel poly(L-lactic acid)/hyaluronic acid macroporous hybrid scaffolds: characterization and assessment of cytotoxicity.

    PubMed

    Antunes, J C; Oliveira, J M; Reis, R L; Soria, J M; Gmez-Ribelles, J L; Mano, J F

    2010-09-01

    Poly(L-lactic acid), PLLA, a synthetic biodegradable polyester, is widely accepted in tissue engineering. Hyaluronic acid (HA), a natural polymer, exhibits an excellent biocompatibility, influences cell signaling, proliferation, and differentiation. In this study, HA crosslinking was performed by immersion of the polysaccharide in water-acetone mixtures containing glutaraldehyde (GA). The objective of this work is to produce PLLA scaffolds with the pores coated with HA, that could be beneficial for bone tissue engineering applications. PLLA tridimensional scaffolds were prepared by compression molding followed by salt leaching. After the scaffolds impregnation with soluble HA solutions of distinct concentration, a GA-crosslinking reaction followed by inactivation of the unreacted GA with glycine was carried out. An increase on surface roughness is shown by scanning electron microscopy (SEM) with the addition of HA. Toluidine blue staining indicates the present of stable crosslinked HA. An estimation of the HA original weight in the hybrid scaffolds was performed using thermal gravimetric analyses. FTIR-ATR and XPS confirmed the crosslinking reaction. Preliminary in vitro cell culture studies were carried out using a mouse lung fibroblast cell line (L929). SEM micrographs of L929 showed that cells adhered well, spread actively throughout all scaffolds, and grew favorably. A MTS test indicated that cells were viable when cultured onto the surface of all scaffolds, suggesting that the introduction of crosslinked HA did not increase the cytotoxicity of the hybrid scaffolds. PMID:20336752

  10. Radical generating coordination complexes as tools for rapid and effective fragmentation and fluorescent labeling of nucleic acids for microchip hybridization.

    SciTech Connect

    Kelly, J. J.; Chernov, B. N.; Mirzabekov, A. D.; Bavykin, S. G.; Biochip Technology Center; Northwestern Univ.; Engelhardt Inst. of Molecular Biology

    2002-01-01

    DNA microchip technology is a rapid, high-throughput method for nucleic acid hybridization reactions. This technology requires random fragmentation and fluorescent labeling of target nucleic acids prior to hybridization. Radical-generating coordination complexes, such as 1,10-phenanthroline-Cu(II) (OP-Cu) and Fe(II)-EDTA (Fe-EDTA), have been commonly used as sequence nonspecific 'chemical nucleases' to introduce single-strand breaks in nucleic acids. Here we describe a new method based on these radical-generating complexes for random fragmentation and labeling of both single- and double-stranded forms of RNA and DNA. Nucleic acids labeled with the OP-Cu and the Fe-EDTA protocols revealed high hybridization specificity in hybridization with DNA microchips containing oligonucleotide probes selected for identification of 16S rRNA sequences of the Bacillus group microorganisms.We also demonstrated cDNA- and cRNA-labeling and fragmentation with this method. Both the OP-Cu and Fe-EDTA fragmentation and labeling procedures are quick and inexpensive compared to other commonly used methods. A column-based version of the described method does not require centrifugation and therefore is promising for the automation of sample preparations in DNA microchip technology as well as in other nucleic acid hybridization studies.

  11. Marangoni instability in the iodate–arsenous acid reaction front

    SciTech Connect

    Pópity-Tóth, Éva; Pótári, Gábor; Erdős, István; Tóth, Ágota; Horváth, Dezső

    2014-07-28

    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.

  12. Porous Zirconium-Phytic Acid Hybrid: a Highly Efficient Catalyst for Meerwein-Ponndorf-Verley Reductions.

    PubMed

    Song, Jinliang; Zhou, Baowen; Zhou, Huacong; Wu, Lingqiao; Meng, Qinglei; Liu, Zhimin; Han, Buxing

    2015-08-01

    The utilization of compounds from natural sources to prepare functional materials is of great importance. Herein, we describe for the first time the preparation of organic-inorganic hybrid catalysts by using natural phytic acid as building block. Zirconium phosphonate (Zr-PhyA) was synthesized by reaction of phytic acid and ZrCl4 and was obtained as a mesoporous material with pore sizes centered around 8.5 nm. Zr-PhyA was used to catalyze the mild and selective Meerwein-Ponndorf-Verley (MPV) reduction of various carbonyl compounds, e.g., of levulinic acid and its esters into γ-valerolactone. Further studies indicated that both Zr and phosphate groups contribute significantly to the excellent performance of Zr-PhyA. PMID:26177726

  13. Bipolar lead-acid battery for hybrid vehicles

    NASA Astrophysics Data System (ADS)

    Saakes, M.; Woortmeijer, R.; Schmal, D.

    Within the framework of the European project bipolar lead-acid power source (BILAPS), a new production route is being developed for the bipolar lead-acid battery. The performance targets are 500 W kg -1, 30 Wh kg -1 and 100 000 power-assist life cycles (PALCs). The operation voltage of the battery can be, according to the requirements, 12, 36 V or any other voltage. Tests with recently developed 4 and 12 V prototypes, each of 30 Ah capacity have demonstrated that the PALC can be operated using 10 C discharge and 9 C charge peaks. The tests show no overvoltage or undervoltage problems during three successive test periods of 16 h with 8 h rest in between. The temperature stabilizes during these tests at 40-45 °C using a thermal-management system. The bipolar lead acid battery is operated at an initial 50% state-of-charge. During the tests, the individual cell voltages display only very small differences. Tests are now in progress to improve further the battery-management system, which has been developed at the cell level, during the period no PALCs are run in order to improve the hybrid behaviour of the battery. The successful tests show the feasibility of operating the bipolar lead-acid battery in a hybrid mode. The costs of the system are estimated to be much lower than those for nickel-metal-hydride or Li-ion based high-power systems. An additional advantage of the lead-acid system is that recycling of lead-acid batteries is well established.

  14. Rapid typing of herpes simplex virus isolates by deoxyribonucleic acid:deoxyribonucleic acid hybridization.

    PubMed Central

    Brautigam, A R; Richman, D D; Oxman, M N

    1980-01-01

    A method for typing clinical isolates of herpes simplex virus was developed. It utilizes hybridization between unlabeled deoxyribonucleic acid from infected cultures and tritium-labeled virus deoxyribonucleic acid, and it can be completed within a day using a single roller-tube culture of the clinical isolated. The data obtained are inherently quantitative, and the method yields unequivocal identification and typing. Thirty-nine coded clinical isolates were all correctly typed by this method. PMID:6262368

  15. Studies on the reaction of nitric acid and sugar

    SciTech Connect

    MacDougall, C.S.; Bayne, C.K.; Roberson, R.B.

    1982-07-01

    The design of vessels and off-gas systems for denitrating acidic radioactive process solutions by reacting nitric acid with sugar requires a fairly accurate determination of the rate of the controlling step. Therefore, the reaction of sugar with concentrated nitric acid was closely examined at temperatures of 100 and 110/sup 0/C and in the presence of low levels of iron )0 to 0.2 M Fe(III)). Efficiencies of the sugar destruction by nitric acid ranged from 2.56 to 2.93 mol of acid consumed per mole of carbon added. Product off-gases were examined throughout the reaction. Release of CO was fairly constant throughout the reaction, but amounts of CO/sub 2/ increased as the nitric acid began to attack the terminal carboxylic acids produced from the consumption of sucrose. Voluminous quantities of NO/sub 2/ were released at the beginning of the reaction, but larger relative concentrations of NO were observed toward the end.

  16. Improved DNA hybridization parameters by Twisted Intercalating Nucleic Acid (TINA).

    PubMed

    Schneider, Uffe Vest

    2012-01-01

    This thesis establishes oligonucleotide design rules and applications of a novel group of DNA stabilizing molecules collectively called Twisted Intercalating Nucleic Acid - TINA. Three peer-reviewed publications form the basis for the thesis. One publication describes an improved and rapid method for determination of DNA melting points and two publications describe the effects of positioning TINA molecules in parallel triplex helix and antiparallel duplex helix forming DNA structures. The third publication establishes that TINA molecules containing oligonucleotides improve an antiparallel duplex hybridization based capture assay's analytical sensitivity compared to conventionel DNA oligonucleotides. Clinical microbiology is traditionally based on pathogenic microorganisms' culture and serological tests. The introduction of DNA target amplification methods like PCR has improved the analytical sensitivity and total turn around time involved in clinical diagnostics of infections. Due to the relatively weak hybridization between the two strands of double stranded DNA, a number of nucleic acid stabilizing molecules have been developed to improve the sensitivity of DNA based diagnostics through superior binding properties. A short introduction is given to Watson-Crick and Hoogsteen based DNA binding and the derived DNA structures. A number of other nucleic acid stabilizing molecules are described. The stabilizing effect of TINA molecules on different DNA structures is discussed and considered in relation to other nucleic acid stabilizing molecules and in relation to future use of TINA containing oligonucleotides in clinical diagnostics and therapy. In conclusion, design of TINA modified oligonucleotides for antiparallel duplex helixes and parallel triplex helixes follows simple purpose dependent rules. TINA molecules are well suited for improving multiplex PCR assays and can be used as part of novel technologies. Future research should test whether combinations of TINA molecules and other nucleic acid stabilizing molecules can increase analytical sensitivity whilst maintaining nucleobase mismatch discrimination in triplex helix based diagnostic assays. PMID:22239845

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

    PubMed

    Salis, Howard; Kaznessis, Yiannis

    2005-02-01

    The dynamical solution of a well-mixed, nonlinear stochastic chemical kinetic system, described by the Master equation, may be exactly computed using the stochastic simulation algorithm. However, because the computational cost scales with the number of reaction occurrences, systems with one or more "fast" reactions become costly to simulate. This paper describes a hybrid stochastic method that partitions the system into subsets of fast and slow reactions, approximates the fast reactions as a continuous Markov process, using a chemical Langevin equation, and accurately describes the slow dynamics using the integral form of the "Next Reaction" variant of the stochastic simulation algorithm. The key innovation of this method is its mechanism of efficiently monitoring the occurrences of slow, discrete events while simultaneously simulating the dynamics of a continuous, stochastic or deterministic process. In addition, by introducing an approximation in which multiple slow reactions may occur within a time step of the numerical integration of the chemical Langevin equation, the hybrid stochastic method performs much faster with only a marginal decrease in accuracy. Multiple examples, including a biological pulse generator and a large-scale system benchmark, are simulated using the exact and proposed hybrid methods as well as, for comparison, a previous hybrid stochastic method. Probability distributions of the solutions are compared and the weak errors of the first two moments are computed. In general, these hybrid methods may be applied to the simulation of the dynamics of a system described by stochastic differential, ordinary differential, and Master equations. PMID:15740306

  18. Final Report Nucleic Acid System - Hybrid PCR and Multiplex Assay Project Phase 2

    SciTech Connect

    Koopman, R P; Langlois, R G; Nasarabadi, S; Benett, W J; Colston, B W; Johnson, D C; Brown, S B; Stratton, P L; Milanovich, F P

    2002-04-17

    This report covers phase 2 (year 2) of the Nucleic Acid System--Hybrid PCR and Multiplex Assay project. The objective of the project is to reduce to practice the detection and identification of biological warfare pathogens by the nucleic acid recognition technique of PCR (polymerase chain reaction) in a multiplex mode using flow cytometry. The Hybrid instrument consists of a flow-through PCR module capable of handling a multiplexed PCR assay, a hybridizing module capable of hybridizing multiplexed PCR amplicons and beads, and a flow cytometer module for bead-based identification, all controlled by a single computer. Multiplex immunoassay using bead-based Luminex flow cytometry is available, allowing rapid screening for many agents. PCR is highly specific and complements and verifies immunoassay. It can also be multiplexed and detection provided using the bead-based Luminex flow cytometer. This approach allows full access to the speed and 100-fold multiplex capability of flow cytometry for rapid screening as well as the accuracy and specificity of PCR. This project has two principal activities: (1) Design, build and test a prototype hybrid PCR/flow cytometer with the basic capabilities for rapid, broad spectrum detection and identification, and (2) Develop and evaluate multiplex flow analysis assay protocols and reagents for the simultaneous detection of PCR products. This project requires not only building operationally functional instrumentation but also developing the chemical assays for detection of priority pathogens. This involves development and evaluation of multiplex flow analysis assay protocols and reagents for the simultaneous detection of PCR products.

  19. Growth characteristics of Ti-based fumaric acid hybrid thin films by molecular layer deposition.

    PubMed

    Cao, Yan-Qiang; Zhu, Lin; Li, Xin; Cao, Zheng-Yi; Wu, Di; Li, Ai-Dong

    2015-09-01

    Ti-based fumaric acid hybrid thin films were successfully prepared using inorganic TiCl4 and organic fumaric acid as precursors by molecular layer deposition (MLD). The effect of deposition temperature from 180 °C to 350 °C on the growth rate, composition, chemical state, and topology of hybrid films has been investigated systematically by means of a series of analytical tools such as spectroscopic ellipsometry, atomic force microscopy (AFM), high resolution X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The MLD process of the Ti-fumaric acid shows self-limiting surface reaction with a reasonable growth rate of ∼0.93 Å per cycle and small surface roughness of ∼0.59 nm in root-mean-square value at 200 °C. A temperature-dependent growth characteristic has been observed in the hybrid films. On increasing the temperature from 180 °C to 300 °C, the growth rate decreases from 1.10 to 0.49 Å per cycle and the XPS composition of the film's C : O : Ti ratio changes from 8.35 : 7.49 : 1.00 to 4.66 : 4.80 : 1.00. FTIR spectra indicate that the hybrid films show bridging bonding mode at a low deposition temperature of 200 °C and bridging/bidentate mixed bonding mode at elevated deposition temperatures of 250 and 300 °C. The higher C and O amounts deviating from the ideal composition may be ascribed to increased organic incorporation into the hybrid films at lower deposition temperature and temperature-dependent density of reactive sites (-OH). The composition of hybrid films grown at 350 °C shows a dramatic decrease in C and O elemental composition (C : O : Ti = 1.97 : 2.76 : 1.00) due to the thermal decomposition of the fumaric acid precursor. The produced by-product H2O changes the structure of the hybrid films, resulting in the formation of more Ti-O bonds at high temperatures. The stability of the hybrid films against chemical and thermal treatment, and long-term storage by vacuum-packing was explored carefully. It is found that the ultrathin hybrid film can be transformed into TiO2 nanoparticles via various post deposition annealing processes with different topographies. Finally, the charge trapping ability of the hybrid film is confirmed by fabricating a charge trapping memory capacitor in which the hybrid film was inserted as a charge trapping layer. PMID:26219386

  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. Precompound decay in heavy ion reactions via the hybrid model

    SciTech Connect

    Blann, M.

    1987-04-01

    The hybrid model for precompound decay is applied to the calculation of neutron spectra following the /sup 20/Ne and /sup 12/C bombardment of /sup 165/Ho at 220, 292, (/sup 20/Ne), and 300 (/sup 12/C) MeV. Results are compared with experimentally deduced angle integrated spectra and with results of the Boltzmann master equation. Both models give excellent agreement with experimentally deduced spectra.

  2. 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

  3. Manipulating surface reactions in lithium-sulphur batteries using hybrid anode structures

    SciTech Connect

    Huang, C; Xiao, J; Shao, YY; Zheng, JM; Bennett, WD; Lu, DP; Saraf, LV; Engelhard, M; Ji, LW; Zhang, J; Li, XL; Graff, GL; Liu, J

    2014-01-09

    Lithium-sulphur batteries have high theoretical energy density and potentially low cost, but significant challenges such as severe capacity degradation prevent its widespread adoption. Here we report a new design of lithium-sulphur battery using electrically connected graphite and lithium metal as a hybrid anode to control undesirable surface reactions on lithium. Lithiated graphite placed in front of the lithium metal functions as an artificial, self-regulated solid electrolyte interface layer to actively control the electrochemical reactions and minimize the deleterious side reactions, leading to significant performance improvements. Lithium-sulphur cells incorporating this hybrid anodes deliver capacities of >800 mAhg(-1) for 400 cycles at a high rate of 1,737mAg(-1), with only 11% capacity fade and a Coulombic efficiency >99%. This simple hybrid concept may also provide scientific strategies for protecting metal anodes in other energy-storage devices.

  4. Manipulating surface reactions in lithium-sulphur batteries using hybrid anode structures

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    Lithium-sulphur batteries have high theoretical energy density and potentially low cost, but significant challenges such as severe capacity degradation prevent its widespread adoption. Here we report a new design of lithium-sulphur battery using electrically connected graphite and lithium metal as a hybrid anode to control undesirable surface reactions on lithium. Lithiated graphite placed in front of the lithium metal functions as an artificial, self-regulated solid electrolyte interface layer to actively control the electrochemical reactions and minimize the deleterious side reactions, leading to significant performance improvements. Lithium-sulphur cells incorporating this hybrid anodes deliver capacities of >800mAhg-1 for 400 cycles at a high rate of 1,737mAg-1, with only 11% capacity fade and a Coulombic efficiency >99%. This simple hybrid concept may also provide scientific strategies for protecting metal anodes in other energy-storage devices.

  5. 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.

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

    DOEpatents

    Lucas, Joe N.; Straume, Tore; Bogen, Kenneth T.

    1997-01-01

    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. Reactions of Thiocyanate Ions with Acid: A Laboratory Experiment.

    ERIC Educational Resources Information Center

    Glidewell, Christopher; And Others

    1984-01-01

    Background information, procedures, and typical results are provided for a three-part experiment involving reactions of potassium thiocynate (KNCS) with sulfuric acid. The experiment represents the final stage of structured work prior to students' research projects during their final year. (JM)

  8. Electrochemical sensor for glutathione detection based on mercury ion triggered hybridization chain reaction signal amplification.

    PubMed

    Wang, Yonghong; Jiang, Lun; Leng, Qinggang; Wu, Yaohui; He, Xiaoxiao; Wang, Kemin

    2016-03-15

    In this work, we design a new simple and highly sensitive strategy for electrochemical detection of glutathione (GSH) via mercury ion (Hg(2+)) triggered hybridization chain reaction (HCR) signal amplification. It is observed that in the absence of GSH, a specific thymine-Hg(2+)-thymine (T-Hg(2+)-T) coordination can fold into hairpin structures. While in the presence of GSH, it thus can be chelated with Hg(2+), resulting in Hg(2+) released from the T-Hg(2+)-T hairpin complex which then forms into ssDNA structure to further hybridize with the surface-immobilized capture DNA probe on the gold electrode with a sticky tail left. The presence of two hairpin helper probes through HCR leads to the formation of extended dsDNA superstructure on the electrode surface, which therefore causes the intercalation of numerous electroactive species ([Ru(NH3)6](3+)) into the dsDNA grooves, followed by a significantly amplified signal output whose intensity is related to the concentration of the GSH. Taking advantage of merits of enzyme-free amplification power of the HCR, the inherent high sensitivity of the electrochemical technique, and label-free detection which utilizes an electroactive species as a signaling molecule that binds to the anionic phosphate backbone of DNA strands via electrostatic force, not only does the proposed strategy enable sensitive detection of GSH, but show high selectivity against other amino acid, making our method a simple and sensitive addition to the amplified GSH detection. PMID:26528805

  9. 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.

  10. Degradation of p-hydroxyphenylacetic acid by photoassisted Fenton reaction.

    PubMed

    Acero, L L; Benítez, F J; Real, F J; Leal, A I

    2001-01-01

    The chemical decomposition of p-hydroxyphenylacetic acid, a phenolic pollutant present in agro-industrial plant effluents, has been investigated by means of the Fenton's reaction and the photoassisted Fenton's reaction, the so-called photo-Fenton system. The degradation levels achieved have been compared to those obtained by applying other Advanced Oxidation Processes, such as the combination UV/H2O2. The optimum pH to carry out the decomposition of this organic compound by either Fenton or photo-Fenton systems was found to be pH = 3. The presence of buffers such as phosphate impedes these processes due to the formation of ferric complexes. A reaction mechanism, which allows calculating the contribution of the radical reaction to the global process, has been proposed. According to this mechanism, the dominant way of degradation of p-hydroxyphenylacetic acid is through its reaction with the OH radicals originated in the photolysis of H2O2 and, especially, in the Fenton's reaction. PMID:11695475

  11. Preparation of an imogolite/poly(acrylic acid) hybrid gel.

    PubMed

    Lee, Hoik; Ryu, Jungju; Kim, Donghyun; Joo, Yongho; Lee, Sang Uck; Sohn, Daewon

    2013-09-15

    Many efforts in the field of hydrogels have been focused toward increasing the mechanical strength of the gel using inorganic materials. In this study, we synthesized a hydrogel that has excellent mechanical properties using surface-modified inorganic nanofibers composed of imogolite (Al2SiO3(OH)4), which is a hydrated aluminum silicate that has a hollow tube structure. Gamma ray radiation generates peroxide radicals on the nanofibers (imogolite), resulting in an additive free hybrid hydrogel. Structural optimization was carried out by changing the composition of imogolite and poly(acrylic acid). Chemical bonding between the nanofiber and the polymer was simulated by a cluster model and characterized by wide area Raman spectroscopy. The results indicate that imogolite embedded in a polymer matrix can align along the direction of an elongational force, as confirmed by small angle X-ray scattering (SAXS). PMID:23806414

  12. Detection and isolation of nucleic acid sequences using a bifunctional hybridization probe

    DOEpatents

    Lucas, Joe N.; Straume, Tore; Bogen, Kenneth T.

    2000-01-01

    A method for detecting and isolating a target sequence in a sample of nucleic acids is provided using a bifunctional hybridization probe capable of hybridizing to the target sequence that includes a detectable marker and a first complexing agent capable of forming a binding pair with a second complexing agent. A kit is also provided for detecting a target sequence in a sample of nucleic acids using a bifunctional hybridization probe according to this method.

  13. Hydroxyapatite-phosphonoformic acid hybrid compounds prepared by hydrothermal method

    NASA Astrophysics Data System (ADS)

    Turki, Thouraya; Othmani, Masseoud; Bantignies, Jean-Louis; Bouzouita, Khaled

    2014-01-01

    Hydroxyapatites were prepared in the presence of different amounts of phosphonoformic acid (PFA) via the hydrothermal method. The obtained powders were characterized through chemical analysis, XRD, IR, 31P MAS-NMR, TEM, and TG-TDA. The XRD showed that the PFA did not affect the apatite composition. Indeed, only a reduction of the crystallite size was noted. After grafting of PFA, the IR spectroscopy revealed the appearance of new bands belonging to HPO42- and carboxylate groups of the apatite and organic moiety, respectively. Moreover, the 31P MAS-NMR spectra exhibited a peak with a low intensity assigned to the terminal phosphonate group of the organic moiety in addition to that of the apatite. Based on these results, a reaction mechanism involving the surface hydroxyl groups (tbnd Casbnd OH) of the apatite and the carboxyl group of the acid was proposed.

  14. Tribochemical reaction dynamics of molybdenum dithiocarbamate on nascent iron surface: a hybrid quantum chemical/classical molecular dynamics study.

    PubMed

    Onodera, Tasuku; Morita, Yusuke; Suzuki, Ai; Sahnoun, Riadh; Koyama, Michihisa; Tsuboi, Hideyuki; Hatakeyama, Nozomu; Endou, Akira; Takaba, Hiromitsu; Del Carpio, Carlos A; Deka, Ramesh C; Kubo, Momoji; Miyamoto, Akira

    2010-04-01

    Using a hybrid quantum chemical/classical molecular dynamics method, we have studied the tribochemical reaction dynamics of molybdenum dithiocarbamate (MoDTC), a commonly used friction modifier in automobile engine oils. MoDTC molecule adsorbed on rubbing nascent iron surface was situated. We firstly investigated the dynamic behavior of MoDTC molecule on the rubbing Fe(001) surface. During the friction simulation, the elongation of Mo-O bonds was observed, forming the Mo2S4 and thiocarbamic acid molecules. To unveil the detailed mechanism of this bond elongation, the electronic states of the MoDTC molecule and Fe(001) surface were computed, and the catalytic effects of Fe(001) surface to the molecule was found. We also found that extreme friction would influence the complete Mo-O bond dissociation. By using the hybrid quantum chemical/classical molecular dynamics method, we successfully simulated the tribochemical reaction dynamics of MoDTC as a friction modifier and obtained the influences of nascent iron surface and friction on its chemical reaction. PMID:20355453

  15. Method for nucleic acid hybridization using single-stranded DNA binding protein

    DOEpatents

    Tabor, Stanley; Richardson, Charles C.

    1996-01-01

    Method of nucleic acid hybridization for detecting the presence of a specific nucleic acid sequence in a population of different nucleic acid sequences using a nucleic acid probe. The nucleic acid probe hybridizes with the specific nucleic acid sequence but not with other nucleic acid sequences in the population. The method includes contacting a sample (potentially including the nucleic acid sequence) with the nucleic acid probe under hybridizing conditions in the presence of a single-stranded DNA binding protein provided in an amount which stimulates renaturation of a dilute solution (i.e., one in which the t.sub.1/2 of renaturation is longer than 3 weeks) of single-stranded DNA greater than 500 fold (i.e., to a t.sub.1/2 less than 60 min, preferably less than 5 min, and most preferably about 1 min.) in the absence of nucleotide triphosphates.

  16. Heterogeneous atmospheric reactions - Sulfuric acid aerosols as tropospheric sinks

    NASA Technical Reports Server (NTRS)

    Baldwin, A. C.; Golden, D. M.

    1979-01-01

    The reaction probabilities of various atmospheric species incident on a bulk sulfuric acid surface are measured in order to determine the role of sulfuric acid aerosols as pollutant sinks. Reaction products and unreacted starting materials leaving a Knudsen cell flow reactor after collision at 300 K with a H2SO4 surface or a soot surface were detected by mass spectrometry. Significant collision reaction probabilities are observed on a H2SO4 surface for H2O2, HNO3, HO2NO2, ClONO2, N2O5, H2O and NH3, and on soot for NH3. Estimates of the contribution of heterogeneous reactions to pollutant removal under atmospheric conditions indicate that while aerosol removal in the stratosphere is insignificant (loss rate constants approximately 10 to the -10th/sec), heterogeneous reactions may be the dominant loss process for several tropospheric species (loss rate constant approximately 10 to the -5th/sec, comparable to photolysis rate constants).

  17. Properties of halloysite nanotube epoxy resin hybrids and the interfacial reactions in the systems

    NASA Astrophysics Data System (ADS)

    Liu, Mingxian; Guo, Baochun; Du, Mingliang; Cai, Xiaojia; Jia, Demin

    2007-11-01

    A naturally occurred microtubullar silicate, halloysite nanotubes (HNTs), was co-cured with epoxy/cyanate ester resin to form organic-inorganic hybrids. The coefficient of thermal expansion (CTE) of the hybrids with low HNT concentration was found to be substantially lower than that of the plain cured resin. The moduli of the hybrids in the glassy state and rubbery state were significantly higher than those for the plain cured resin. The dispersion of HNTs in the resin matrix was very uniform as revealed by the transmission electron microscopy (TEM) results. The interfacial reactions between the HNTs and cyanate ester (CE) were revealed by the results of Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS). The substantially increased properties of the hybrids were attributed to the covalent bonding between the nanotubes and the matrix.

  18. Nucleic Acid-Peptide Complex Phase Controlled by DNA Hybridization

    NASA Astrophysics Data System (ADS)

    Vieregg, Jeffrey; Lueckheide, Michael; Leon, Lorraine; Marciel, Amanda; Tirrell, Matthew

    When polyanions and polycations are mixed, counterion release drives formation of polymer-rich complexes that can either be solid (precipitates) or liquid (coacervates) depending on the properties of the polyelectrolytes. These complexes are important in many fields, from encapsulation of industrial polymers to membrane-free segregation of biomolecules such as nucleic acids and proteins. Condensation of long double-stranded DNA has been studied for several decades, but comparatively little attention has been paid to the polyelectrolyte behavior of oligonucleotides. We report here studies of DNA oligonucleotides (10 - 88 nt) complexed with polylysine (10 - 100 aa). Unexpectedly, we find that the phase of the resulting complexes is controlled by the hybridization state of the nucleic acid, with double-stranded DNA forming precipitates and single-stranded DNA forming coacervates. Stability increases with polyelectrolyte length and decreases with solution salt concentration, with complexes of the longer double-stranded polymers undergoing precipitate/coacervate/soluble transitions as ionic strength is increased. Mixing coacervates formed by complementary single-stranded oligonucleotides results in precipitate formation, raising the possibility of stimulus-responsive material design.

  19. Amphiphilic DNA block copolymers: nucleic acid-polymer hybrid materials for diagnostics and biomedicine.

    PubMed

    Zimmermann, Jan; Kwak, Minseok; Musser, Andrew J; Herrmann, Andreas

    2011-01-01

    DNA-polymer conjugates have been recognized as versatile functional materials in many different fields ranging from nanotechnology to diagnostics and biomedicine. They combine the favorable properties of nucleic acids and synthetic polymers. Moreover, joining both structures with covalent bonds to form bioorganic hybrids allows for the tuning of specific properties or even the possibility of evolving completely new functions. One important class of this type of material is amphiphilic DNA block copolymers, which, due to microphase separation, can spontaneously adopt nanosized micelle morphologies with a hydrophobic core and a DNA corona. These DNA nano-objects have been explored as vehicles for targeted gene and drug delivery, and also as programmable nanoreactors for organic reactions. Key to the successful realization of these potential applications is that (1) DNA block copolymer conjugates can be fabricated in a fully automated fashion by employing a DNA synthesizer; (2) hydrophobic compounds can be loaded within their interior; and (3) they can be site-specifically functionalized by a convenient nucleic acid hybridization procedure. This chapter aims to broaden the range of biodiagnostic and biomedical applications of these materials by providing a comprehensive outline of the preparation and characterization of multifunctional DNA-polymer nanoparticles. PMID:21674335

  20. Highly enantioselective Biginelli reaction catalyzed by SPINOL-phosphoric acids.

    PubMed

    Xu, Fangxi; Huang, Dan; Lin, Xufeng; Wang, Yanguang

    2012-06-14

    A highly enantioselective Biginelli reaction promoted by chiral spirocyclic SPINOL-phosphoric acids has been developed. Under the optimized conditions with 5 mol% catalyst loading, a wide range of optically active dihydropyrimidinethiones (DHPMs) were obtained in high yields (up to 98%) with good to excellent enantioselectivities (up to 99% ee). The synthetic utility of this method was demonstrated by the synthesis of chiral precursors of three drugs, including (S)-Monastrol, (S)-L-771688 and (S)-SQ 32926. PMID:22565820

  1. 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

  2. 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

  3. [The reactions between acidic phenolsulfonphthaleins and human serum albumin].

    PubMed

    Liu, Bao-sheng; Zhang, Hong-yi; Wang, Fu-li

    2003-06-01

    The reactions between HSA and acidic phenolsulfonphthaleins, including phenol red, cresol red, chlorophenol red, bromocresol purple and m-cresol purple, have been investigated by fluorescence spectrometry. The experiments showed that all of the selected acidic phenolsulfonphthaleins strongly quenched the fluorescence produced by HSA, and this fluorescence quenching could be interpreted in terms of statistic quenching. From the calculation results of binding constants K for these dyes at various temperatures, it could be found that the increase in the functional groups numbers of dyes molecules resulted in an increase in K, while the increase in reaction temperature led to a decrease in K. The interactions between dyes and HSA were attributed to static-electricity gravitation, which was confirmed by the calculation results of enthalpy and entropy for these reactions. According to the non-radiation energy transfer theory, the distances and energy transfer efficiencies between dyes and protein at various temperatures were obtained. These results further supported the conclusion that these reactions belonged to the single static quenching caused by the energy transfer. PMID:12953536

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

    DOEpatents

    Nasarabadi, Shanavaz

    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.

  5. Serum uric acid levels during leprosy reaction episodes

    PubMed Central

    Alves-Junior, Eduardo R.; Arruda, Talita A.; Lopes, Jose C.; Fontes, Cor J.F.

    2016-01-01

    Background. Leprosy reactions are acute inflammatory episodes that occur mainly in the multibacillary forms of the disease. The reactions are classified as type 1 (reverse reaction) or type 2 (erythema nodosum leprosum). Leprosy-associated oxidative stress has been widely demonstrated. Several recent studies have shown uric acid (UA) to have antioxidative effects under pathologic conditions. The objective of this study was to assess serum levels of UA in patients with leprosy reactions, with the aim of monitoring their levels before and after treatment, compared with levels in leprosy patients without reactions. Methods. The study included patients aged 18–69 years assisted at a leprosy treatment reference center in the Central Region of Brazil. Patients who were pregnant; were using immunosuppressant drugs or immunobiologicals; or had an autoimmune disease, human immunodeficiency virus infection, acquired immune deficiency syndrome, or tuberculosis were excluded. Upon recruitment, all individuals were clinically assessed for skin lesions and neural or systemic impairment. Some patients had already completed treatment for leprosy, while others were still undergoing treatment or had initiated treatment after being admitted. The treatment of the reactional episode was started only after the initial evaluation. Laboratory assessments were performed upon admission (baseline) and at approximately 30 and 60 days (time points 1 and 2, respectively). Results. A total of 123 leprosy patients were recruited between June 2012 and June 2015; among them, 56, 42, and 25 presented with type 1, type 2, and no reactions, respectively. Serum UA levels were significantly reduced in patients with type 2 leprosy reactions compared with patients in the control group and remained lower in the two subsequent assessments, after initiation of anti-reaction treatments, with similar values to those recorded before the treatment. Discussion. The decreased serum UA levels in patients with type 2 leprosy reactions might be due to the consumption of UA to neutralize the enhanced production of oxygen- and nitrogen-reactive species that occurs during type 2 reactions. The maintenance of the reduced levels in the follow-up assessments may indicate persistence of oxidative stress in the initial post-treatment stages, despite improved clinical conditions. The results of this study suggest that serum UA may play an antioxidative role during type 2 leprosy reactions. PMID:26989632

  6. Serum uric acid levels during leprosy reaction episodes.

    PubMed

    Morato-Conceicao, Yvelise T; Alves-Junior, Eduardo R; Arruda, Talita A; Lopes, Jose C; Fontes, Cor J F

    2016-01-01

    Background. Leprosy reactions are acute inflammatory episodes that occur mainly in the multibacillary forms of the disease. The reactions are classified as type 1 (reverse reaction) or type 2 (erythema nodosum leprosum). Leprosy-associated oxidative stress has been widely demonstrated. Several recent studies have shown uric acid (UA) to have antioxidative effects under pathologic conditions. The objective of this study was to assess serum levels of UA in patients with leprosy reactions, with the aim of monitoring their levels before and after treatment, compared with levels in leprosy patients without reactions. Methods. The study included patients aged 18-69 years assisted at a leprosy treatment reference center in the Central Region of Brazil. Patients who were pregnant; were using immunosuppressant drugs or immunobiologicals; or had an autoimmune disease, human immunodeficiency virus infection, acquired immune deficiency syndrome, or tuberculosis were excluded. Upon recruitment, all individuals were clinically assessed for skin lesions and neural or systemic impairment. Some patients had already completed treatment for leprosy, while others were still undergoing treatment or had initiated treatment after being admitted. The treatment of the reactional episode was started only after the initial evaluation. Laboratory assessments were performed upon admission (baseline) and at approximately 30 and 60 days (time points 1 and 2, respectively). Results. A total of 123 leprosy patients were recruited between June 2012 and June 2015; among them, 56, 42, and 25 presented with type 1, type 2, and no reactions, respectively. Serum UA levels were significantly reduced in patients with type 2 leprosy reactions compared with patients in the control group and remained lower in the two subsequent assessments, after initiation of anti-reaction treatments, with similar values to those recorded before the treatment. Discussion. The decreased serum UA levels in patients with type 2 leprosy reactions might be due to the consumption of UA to neutralize the enhanced production of oxygen- and nitrogen-reactive species that occurs during type 2 reactions. The maintenance of the reduced levels in the follow-up assessments may indicate persistence of oxidative stress in the initial post-treatment stages, despite improved clinical conditions. The results of this study suggest that serum UA may play an antioxidative role during type 2 leprosy reactions. PMID:26989632

  7. The thiobarbituric acid (TBA) reaction in foods: a review.

    PubMed

    Guillén-Sans, R; Guzmán-Chozas, M

    1998-05-01

    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 malonaldehyde (MDA) precursors. The absorption spectrum obtained with oxidized fatty foods is like the spectrum obtained when TBA and MDA react. However, during the secondary phase of the autoxidation process other aldehydes (alkanals, 2-alkenals, dienals) are formed which react with TBA, and they are responsible for off-flavors. Three kinds of pigments (yellow, orange, red adducts) are involved. Also, aromatic aldehydes, which constitute the flavor profile of diverse fruits and essential oils, form with TBA the characteristic arylidene-2-TBA acids. Other substances, such as ketones, ketosteroids, acids, esters, sugars, imides and amides, amino acids, oxidized proteins, pyridines, pyrimidines, and vitamins can react with TBA; they are named TBARS (substances that react with TBA), and form principally in meats and meat derivatives. Several organic or bio-organic acids, as shikimic and sorbic acids, react photometrically with TBA if a Malaprade reaction takes place before. A structural study of the red adduct TBA-MDA has been carried out. PMID:9626489

  8. A hybrid potential reaction path and free energy study of the chorismate mutase reaction.

    PubMed

    Martí, S; Andrés, J; Moliner, V; Silla, E; Tuñón, I; Bertrán, J; Field, M J

    2001-02-28

    We present a combination of two techniques--QM/MM statistical simulation methods and QM/MM internal energy minimizations--to get a deeper insight into the reaction catalyzed by the enzyme chorismate mutase. Structures, internal energies and free energies, taken from the paths of the reaction in solution and in the enzyme have been analyzed in order to estimate the relative importance of the reorganization and preorganization effects. The results we obtain for this reaction are in good agreement with experiment and show that chorismate mutase achieves its catalytic efficiency in two ways; first, it preferentially binds the active conformer of the substrate and, second, it reduces the free energy of activation for the reaction relative to that in solution by providing an environment which stabilizes the transition state. PMID:11456771

  9. Variability in coconut (Cocos nucifera L.) germplasm and hybrids for fatty acid profile of oil.

    PubMed

    Kumar, S Naresh

    2011-12-28

    Coconut oil, the main product of coconut fruit, is the richest source of glycerol and lauric acid and hence is called lauric oil. This paper reports the fatty acid profile of oil from 60 Talls, 14 Dwarfs, and 34 hybrids. These include collections from 13 countries covering a large coconut-growing area of the world, apart from the indigenous ones. Capillary gas chromatography analysis of oil indicated a wider variation for the fatty acid profile than earlier reported. Apart from this, for the first time other fatty acids such as behenic and lignoceric acids were detected. Oil from cultivars and hybrids of coconut has significantly differed, particularly for commercially important fatty acids such as lauric acid and unsaturated fatty acids. However, coconut oil seems to have a conserved fatty acid profile, mainly because of low unsaturated fatty acids, indicating the possibility of grouping cultivars on the basis of their fatty acid profiles. The cluster analysis based on fatty acid profile indicated grouping together of geographically and typically closely related cultivars. Cultivars with high concentrations of specific fatty acids can be of potential use for industrial exploitation, whereas those with high concentrations of short- and medium-chain fatty acids and unsaturated fatty acids are more suitable for human consumption. Cultivars and hybrids with high and low values for each of the fatty acids are also identified. PMID:22118628

  10. Theoretical study of the reaction mechanism of phenolic acid decarboxylase.

    PubMed

    Sheng, Xiang; Lind, Maria E S; Himo, Fahmi

    2015-12-01

    The cofactor-free phenolic acid decarboxylases (PADs) catalyze the non-oxidative decarboxylation of phenolic acids to their corresponding p-vinyl derivatives. Phenolic acids are toxic to some organisms, and a number of them have evolved the ability to transform these compounds, including PAD-catalyzed reactions. Since the vinyl derivative products can be used as polymer precursors and are also of interest in the food-processing industry, PADs might have potential applications as biocatalysts. We have investigated the detailed reaction mechanism of PAD from Bacillus subtilis using quantum chemical methodology. A number of different mechanistic scenarios have been considered and evaluated on the basis of their energy profiles. The calculations support a mechanism in which a quinone methide intermediate is formed by protonation of the substrate double bond, followed by C-C bond cleavage. A different substrate orientation in the active site is suggested compared to the literature proposal. This suggestion is analogous to other enzymes with p-hydroxylated aromatic compounds as substrates, such as hydroxycinnamoyl-CoA hydratase-lyase and vanillyl alcohol oxidase. Furthermore, on the basis of the calculations, a different active site residue compared to previous proposals is suggested to act as the general acid in the reaction. The mechanism put forward here is consistent with the available mutagenesis experiments and the calculated energy barrier is in agreement with measured rate constants. The detailed mechanistic understanding developed here might be extended to other members of the family of PAD-type enzymes. It could also be useful to rationalize the recently developed alternative promiscuous reactivities of these enzymes. PMID:26408050

  11. Gibberellic Acid-induced Phase Change in Hedera helix as Studied by Deoxyribonucleic Acid-Ribonucleic Acid Hybridization 1

    PubMed Central

    Rogler, Charles E.; Dahmus, Michael E.

    1974-01-01

    Applications of gibberellic acid to the mature form of Hedera helix induce morphological reversions to the juvenile form of growth. The juvenile forms produced are stable with time and differ dramatically from the mature in phenotype. DNA-RNA hybridization techniques have been used to study the RNA populations of juvenile, mature and gibberellic acid-treated mature apices. Hybridization competition experiments using RNA extracted by a hot phenol technique and uniformly labeled in vitro with 3H dimethylsulfate show no qualitative differences between the species of RNA present in juvenile and mature apices. However, differences are observed in the frequency distribution of RNA species using both uniformly labeled or pulse-labeled RNA as a reference. RNA extracted from gibberellic acid-treated mature buds was a less effective competitor than control mature RNA and the difference observed was comparable to that observed between mature and juvenile RNA. These results indicate that at least part of the molecular basis of phase change and gibberellic acid action may involve an alteration in the rate of transcription of certain genes in the apices of the mature form. RNA extracted using the hot phenol procedure contained a fraction of rapidly labeled RNA which was not extractable with cold phenol. When RNA extracted only with cold phenol was used in competition experiments sequences unique to the juvenile were detected and sequences unique to the mature were not detected. Implications of these results in relation to possible post-transcriptional control mechanisms are discussed. PMID:16658844

  12. 40 CFR 721.10126 - Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... substituted benezenesulfonic acid reaction product with naphthalenesulfonato azo substituted phenyl azo... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10126 Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with naphthalenesulfonato...

  13. 40 CFR 721.10126 - Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... substituted benezenesulfonic acid reaction product with naphthalenesulfonato azo substituted phenyl azo... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10126 Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with naphthalenesulfonato...

  14. 40 CFR 721.10126 - Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... substituted triazine amino substituted benezenesulfonic acid reaction product with naphthalenesulfonato azo... substituted triazine amino substituted benezenesulfonic acid reaction product with naphthalenesulfonato azo... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkyl amino substituted triazine...

  15. 40 CFR 721.10126 - Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... substituted triazine amino substituted benezenesulfonic acid reaction product with naphthalenesulfonato azo... substituted triazine amino substituted benezenesulfonic acid reaction product with naphthalenesulfonato azo... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkyl amino substituted triazine...

  16. Laboratory measurements of heterogeneous reactions on sulfuric acid surfaces

    NASA Technical Reports Server (NTRS)

    Williams, Leah R.; Manion, Jeffrey A.; Golden, David M.; Tolbert, Margaret A.

    1994-01-01

    Increasing evidence from field, modeling, and laboratory studies suggests that heterogeneous reactions on stratospheric sulfate aerosol particles may contribute to global ozone depletion. Using a Knudsen cell reactor technique, the authors have studied the uptake, reactivity, and solubility of several trace atmospheric species on cold sulfuric acid surfaces representative of stratospheric aerosol particles. The results suggest that the heterogeneous conversion of N2O5 to HNO3 is fast enough to significantly affect the partitioning of nitrogen species in the global stratosphere and thus contribute to global ozone depletion. The hydrolysis of ClONO2 is slower and unlikely to be important under normal conditions at midlatitudes. The solubilities of HCl and HNO3 in sulfuric acid down to 200 K were found to be quite low. For HCl, this means that little HCl is available for reaction on the surfaces of stratospheric sulfate aerosol particles. The low solubility of HNO3 means that this product of heterogeneous reactions will enter the gas phase, and the denitrification observed in polar regions is unlikely to occur in the global stratosphere.

  17. Tag/hybridization-based sensitive detection of polymerase chain reaction products.

    PubMed

    Niwa, Kousuke; Oribe, Akinobu; Okumura, Hidemasa; Shimono, Masahiro; Nagai, Kenkichi; Hirota, Toshikazu; Yasue, Hiroshi; Kawase, Mitsuo

    2014-11-01

    The polymerase chain reaction (PCR) is an important technology to amplify a single copy or a few copies of DNA segment in genomic DNAs, visualizing the segment as DNA fragment. Thus, PCR is frequently used in various examinations such as detection of bacteria and fungi in the food industry. Here, we report a simple and sensitive method for detection of PCR products using single-strand tag sequence and hybridization of the tag sequence to the complementary tag sequence immobilized on solid material (STH). The detection sensitivity was found to be at least 50 times higher than electrophoresis/ethidium bromide (EtBr) visualization for approximately a 500-bp fragment and higher than the ordinary hybridization, that is, hybridization of denatured PCR product to probe sequence immobilized on solid material. PMID:25051253

  18. Artificial mismatch hybridization

    DOEpatents

    Guo, Zhen; Smith, Lloyd M.

    1998-01-01

    An improved nucleic acid hybridization process is provided which employs a modified oligonucleotide and improves the ability to discriminate a control nucleic acid target from a variant nucleic acid target containing a sequence variation. The modified probe contains at least one artificial mismatch relative to the control nucleic acid target in addition to any mismatch(es) arising from the sequence variation. The invention has direct and advantageous application to numerous existing hybridization methods, including, applications that employ, for example, the Polymerase Chain Reaction, allele-specific nucleic acid sequencing methods, and diagnostic hybridization methods.

  19. 40 CFR 721.10211 - Octadecanoic acid, reaction products with diethylenetriamine and urea, acetates.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10211 Octadecanoic acid, reaction... subject to reporting. (1) The chemical substance identified as octadecanoic acid, reaction products with... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Octadecanoic acid, reaction...

  20. 40 CFR 721.10211 - Octadecanoic acid, reaction products with diethylenetriamine and urea, acetates.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10211 Octadecanoic acid, reaction... subject to reporting. (1) The chemical substance identified as octadecanoic acid, reaction products with... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Octadecanoic acid, reaction...

  1. 40 CFR 721.10211 - Octadecanoic acid, reaction products with diethylenetriamine and urea, acetates.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10211 Octadecanoic acid, reaction... subject to reporting. (1) The chemical substance identified as octadecanoic acid, reaction products with... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Octadecanoic acid, reaction...

  2. 40 CFR 721.10211 - Octadecanoic acid, reaction products with diethylenetriamine and urea, acetates.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10211 Octadecanoic acid, reaction... subject to reporting. (1) The chemical substance identified as octadecanoic acid, reaction products with... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Octadecanoic acid, reaction...

  3. Hybrid stochastic simulation of reaction-diffusion systems with slow and fast dynamics

    NASA Astrophysics Data System (ADS)

    Strehl, Robert; Ilie, Silvana

    2015-12-01

    In this paper, we present a novel hybrid method to simulate discrete stochastic reaction-diffusion models arising in biochemical signaling pathways. We study moderately stiff systems, for which we can partition each reaction or diffusion channel into either a slow or fast subset, based on its propensity. Numerical approaches missing this distinction are often limited with respect to computational run time or approximation quality. We design an approximate scheme that remedies these pitfalls by using a new blending strategy of the well-established inhomogeneous stochastic simulation algorithm and the tau-leaping simulation method. The advantages of our hybrid simulation algorithm are demonstrated on three benchmarking systems, with special focus on approximation accuracy and efficiency.

  4. 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.

  5. Acid-catalyzed reactions of epoxides for atmospheric nanoparticle growth.

    PubMed

    Xu, Wen; Gomez-Hernandez, Mario; Guo, Song; Secrest, Jeremiah; Marrero-Ortiz, Wilmarie; Zhang, Annie L; Zhang, Renyi

    2014-11-01

    Although new particle formation accounts for about 50% of the global aerosol production in the troposphere, the chemical species and mechanism responsible for the growth of freshly nucleated nanoparticles remain largely uncertain. Here we show large size growth when sulfuric acid nanoparticles of 4-20 nm are exposed to epoxide vapors, dependent on the particle size and relative humidity. Composition analysis of the nanoparticles after epoxide exposure reveals the presence of high molecular weight organosulfates and polymers, indicating the occurrence of acid-catalyzed reactions of epoxides. Our results suggest that epoxides play an important role in the growth of atmospheric newly nucleated nanoparticles, considering their large formation yields from photochemical oxidation of biogenic volatile organic compounds. PMID:25338124

  6. 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.

  7. 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

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Fatty acids, tall-oil, reaction... NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10629 Fatty acids, tall-oil, reaction products with modified fatty acids and polyalkanolamines (generic)....

  8. 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

    ..., reaction products with alkenoic acid alkyl esters and diamine (generic). 721.10664 Section 721.10664... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10664 Alkenedioic acid dialkyl ester, reaction products with alkenoic acid alkyl esters and diamine (generic)....

  9. 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

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Fatty acids, tall-oil, reaction... NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10629 Fatty acids, tall-oil, reaction products with modified fatty acids and polyalkanolamines (generic)....

  10. 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

    ..., reaction products with alkenoic acid alkyl esters and diamine (generic). 721.10664 Section 721.10664... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10664 Alkenedioic acid dialkyl ester, reaction products with alkenoic acid alkyl esters and diamine (generic)....

  11. Inorganic solid acids and their use in acid-catalyzed hydrocarbon reactions

    SciTech Connect

    Corma, A.

    1995-05-01

    It is possible to say that solid acid catalysis involves the largest amounts of catalysts used and the largest economical effort in the oil refining and chemical industry. In this review the author has tried to describe perhaps the most important solid acids based on inorganic oxides, going from their preparation procedures and characterization, to their catalytic activity for a series of hydrocarbon reactions. The review starts with an introductory part in where the nature of the acid sites and their physicochemical characterization is described. Then the classification to the different catalysts is initiated with the older amorphous silica-alumina and aluminum phosphates and followed by catalysts with more interest at present which are discussed in order of increasing acid strength: zeolites, heteropoly acids, and sulfated metal oxides. The aim of this review is to present an extended summary of the state of the art and the current and the future tendencies in the field. 720 refs.

  12. 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...

  13. Computational determination of fundamental pathway and activation barriers for acetohydroxyacid synthase-catalyzed condensation reactions of alpha-keto acids.

    PubMed

    Xiong, Ying; Liu, Junjun; Yang, Guang-Fu; Zhan, Chang-Guo

    2010-06-01

    Acetohydroxyacid synthase (AHAS) is the first common enzyme in the biosynthetic pathway leading to the production of various branched-chain amino acids. AHAS is recognized as a promising target for new antituberculosis drugs, antibacterial drugs, and herbicides. Extensive first-principles quantum mechanical (QM) and hybrid quantum mechanical/molecular mechanical (QM/MM) calculations have enabled us, in this study, to uncover the fundamental reaction pathway, determine the activation barriers, and obtain valuable insights concerning the specific roles of key amino acid residues for the common steps of AHAS-catalyzed condensation reactions of alpha-keto acids. The computational results reveal that the rate-determining step of the AHAS-catalyzed reactions is the second reaction step and that the most important amino acid residues involved in the catalysis include Glu144', Gln207', Gly121', and Gly511 that form favorable hydrogen bonds with the reaction center (consisting of atoms from the substrate and cofactor) during the reaction process. In addition, Glu144' also accepts a proton from cofactor thiamin diphosphate (ThDP) through hydrogen bonding during the catalytic reaction. The favorable interactions between the reaction center and protein environment remarkably stabilize the transition state and, thus, lower the activation barrier for the rate-determining reaction step by approximately 20 kcal/mol. The activation barrier calculated for the rate-determining step is in good agreement with the experimental activation barrier. The detailed structural and mechanistic insights should be valuable for rational design of novel, potent AHAS inhibitors that may be used as promising new anti-tuberculosis drugs, antibacterial drugs, and/or herbicides to overcome drug resistance problem. PMID:19554557

  14. Nucleic acid hybridization techniques for the detection of bluetongue virus

    SciTech Connect

    Schoepp, R.J.

    1989-01-01

    Virus isolation, antigen detection, and in situ hybridization were compared in their abilities to detect in cell culture, the five serotypes of bluetongue virus (BTV) occurring in the United States, serotypes 2, 10, 11, 13, and 17. For isolation, virus was propagated in baby hamster kidney (BHK-21) cell culture. For antigen detection, two techniques, indirect fluorescent-antibody (IFA) and enzyme immunocytoassay (EICA) were used. For in situ hybridization, a complementary DNA (cDNA) of the L3 RNA genome segment of BTV, serotype 17 (BTV-17) labeled with {sup 35}S was used as a group-specific probe. Virus isolation was the most sensitive technique, often detecting input virus and then detecting virus throughout the course of the study. IFA and EICA were of similar sensitivity and detected BTV antigen shortly after detection of virus by isolation. A direct-blot hybridization technique using a {sup 32}P-labeled, strand-specific RNA transcript probe was developed, optimized, and used to detect BTV in pools of infected Culicoides variipennis midges. The technique was able to detect as few as one infected Culicoides midge in a pool of 100 and as little as 3.5 log{sub 10} TCID{sub 50} per ml of virus. A sandwich hybridization technique was developed and used to detect BTV in pools of infected Culicoides variipennis midges. The sandwich hybridization technique used a single-stranded DNA catcher sequence bound to a solid support and a {sup 32}P-labeled, single-stranded RNA detector sequence. Sandwich hybridization was compared to direct blot hybridization using a strand-specific RNA transcript probe or a cDNA probe. Sandwich hybridization was able to detect as few as one infected Culicoides midge in a pool of 50; however, the technique was approximately tenfold less sensitive than direct blot hybridization.

  15. Radical-generating coordination complexes as tools for rapid and effective fragmentation and fluorescent labeling of nucleic acids for microchip hybridization.

    SciTech Connect

    Kelly, J. J.; Chernov, B. K.; Tovstanovsky, I.; Mirzabekov, A. D.; Bavykin, S. G.; Biochip Technology Center; Northwestern Univ.; Engelhardt Inst. of Molecular Biology

    2002-12-15

    DNA microchip technology is a rapid, high-throughput method for nucleic acid hybridization reactions. This technology requires random fragmentation and fluorescent labeling of target nucleic acids prior to hybridization. Radical-generating coordination complexes, such as 1,10-phenanthroline-Cu(II) (OP-Cu) and Fe(II)-EDTA (Fe-EDTA), have been commonly used as sequence nonspecific 'chemical nucleases' to introduce single-strand breaks in nucleic acids. Here we describe a new method based on these radical-generating complexes for random fragmentation and labeling of both single- and double-stranded forms of RNA and DNA. Nucleic acids labeled with the OP-Cu and the Fe-EDTA protocols revealed high hybridization specificity in hybridization with DNA microchips containing oligonucleotide probes selected for identification of 16S rRNA sequences of the Bacillus group microorganisms.We also demonstrated cDNA- and cRNA-labeling and fragmentation with this method. Both the OP-Cu and Fe-EDTA fragmentation and labeling procedures are quick and inexpensive compared to other commonly used methods. A column-based version of the described method does not require centrifugation and therefore is promising for the automation of sample preparations in DNA microchip technology as well as in other nucleic acid hybridization studies.

  16. Wollastonite hybridizing stearic acid as thermal energy storage material

    NASA Astrophysics Data System (ADS)

    Xu, Dawei; Yang, Huaming

    2014-11-01

    This paper reported on the preparation of a novel stearic acid (SA)/wollastonite (W) composite as a form-stable phase change material (PCM) for thermal energy-storage (TES) by vacuum impregnation, and especially investigated the effect of the size grade of W on the thermal properties of the SA/W composite. Samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), laser particle-size analysis, and differential scanning calorimetry (DSC). Natural W (Wr) was classified into four size grades by wet screening. The results indicate that no chemical reaction took place between SA and W, and the SA load in the SA/W composite increased with an increase in the length/diameter (L/D) ratio of the W. The SA/W composite with a W L/D ratio of 22.5 exhibited latent heats of melting and freezing of 58.64 J/g and 56.95 J/g, respectively, which was higher than those of the composite incorporating natural W. We believe that the as-prepared form-stable PCM composite could provide a potential means of TES for the concentrated solar power.

  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. Facile synthesis of gold nanoparticle (AuNP)-carbon nanotube (CNT) hybrids through an interfacial Michael addition reaction.

    PubMed

    Gobbo, Pierangelo; Biesinger, Mark C; Workentin, Mark S

    2013-04-01

    A CNT-AuNP hybrid has been synthesized through the Michael addition reaction between thiol-functionalized single-wall CNT and small water-soluble Maleimide-AuNP. The resilience and stability of this hybrid nanosystem is ensured by a covalent bond linking the nanoparticle to the CNT and by the fact that the functionalization reaction involves the organic shell of the AuNP and not its metallic core. PMID:23443673

  19. Hybrid molecule from Farnesylthiosalicylic acid-diamine and phenylpropenoic acid as Ras-related signaling inhibitor with potent antitumor activities.

    PubMed

    Ling, Yong; Wang, Zhiqiang; Wang, Xuemin; Li, Xianghua; Wang, Xinyang; Zhang, Wei; Dai, Hong; Chen, Li; Zhang, Yihua

    2015-02-01

    Novel series of Farnesylthiosalicylic acid-diamine/phenylpropenoic acid hybrids were designed and synthesized. Their in vitro growth inhibitory assays showed that most compounds displayed strong antiproliferation activity against seven cancer cells. Especially, the new hybrid 12 f, by the conjugation of 10a with ferulic acid, could selectively suppress the proliferation of tumor cells and display significantly lower toxicities to normal cells than its intermediate 10a. Furthermore, 12 f dose-dependently induced SMMC-7721 cell apoptosis. Additionally, our observations demonstrated that 12 f inhibited both Ras-related signaling and phosphorylated NF-?B synergistically, which may be advantageous to the strong antitumor activities of 12 f. Our findings suggest that these novel hybrids may hold a great promise as therapeutic agents for the intervention of human cancers. PMID:25043275

  20. Palladium-atom catalyzed formic acid decomposition and the switch of reaction mechanism with temperature.

    PubMed

    He, Nan; Li, Zhen Hua

    2016-04-21

    Formic acid decomposition (FAD) reaction has been an innovative way for hydrogen energy. Noble metal catalysts, especially palladium-containing nanoparticles, supported or unsupported, perform well in this reaction. Herein, we considered the simplest model, wherein one Pd atom is used as the FAD catalyst. With high-level theoretical calculations of CCSD(T)/CBS quality, we investigated all possible FAD pathways. The results show that FAD catalyzed by one Pd atom follows a different mechanism compared with that catalyzed by surfaces or larger clusters. At the initial stage of the reaction, FAD follows a dehydration route and is quickly poisoned by CO due to the formation of very stable PdCO. PdCO then becomes the actual catalyst for FAD at temperatures approximately below 1050 K. Beyond 1050 K, there is a switch of catalyst from PdCO to Pd atom. The results also show that dehydration is always favoured over dehydrogenation on either the Pd-atom or PdCO catalyst. On the Pd-atom catalyst, neither dehydrogenation nor dehydration follows the formate mechanism. In contrast, on the PdCO catalyst, dehydrogenation follows the formate mechanism, whereas dehydration does not. We also systematically investigated the performance of 24 density functional theory methods. We found that the performance of the double hybrid mPW2PLYP functional is the best, followed by the B3LYP, B3PW91, N12SX, M11, and B2PLYP functionals. PMID:27005983

  1. Analysis of hepcidin expression: In situ hybridization and quantitative polymerase chain reaction from paraffin sections

    PubMed Central

    Sakuraoka, Yuhki; Sawada, Tokihiko; Shiraki, Takayuki; Park, Kyunghwa; Sakurai, Yuhichiro; Tomosugi, Naohisa; Kubota, Keiichi

    2012-01-01

    AIM: To establish methods for quantitative polymerase chain reaction (PCR) for hepcidin using RNAs isolated from paraffin-embedded sections and in situ hybridization of hepatocellular carcinoma (HCC). METHODS: Total RNA from paraffin-embedded sections was isolated from 68 paraffin-embedded samples of HCC. Samples came from 54 male and 14 female patients with a mean age of 66.8 7.8 years. Quantitative PCR was performed. Immunohistochemistry and in situ hybridization for hepcidin were also performed. RESULTS: Quantitative PCR for hepcidin using RNAs isolated from paraffin-embedded sections of HCC was performed successfully. The expression level of hepcidin mRNA in cancer tissues was significantly higher than that in non-cancer tissues. A method of in situ hybridization for hepcidin was established successfully, and this demonstrated that hepcidin mRNA was expressed in non-cancerous tissue but absent in cancerous tissue. CONCLUSION: We have established novel methods for quantitative PCR for hepcidin using RNAs isolated from paraffin-embedded sections and in situ hybridization of HCC. PMID:22851866

  2. Investigation of Embedded Si/C System Exposed to a Hybrid Reaction of Centrifugal-Assisted Thermite Method.

    PubMed

    Mahmoodian, Reza; Yahya, Rosiyah; Dabbagh, Ali; Hamdi, Mohd; Hassan, Mohsen A

    2015-01-01

    A novel method is proposed to study the behavior and phase formation of a Si+C compacted pellet under centrifugal acceleration in a hybrid reaction. Si+C as elemental mixture in the form of a pellet is embedded in a centrifugal tube. The pellet assembly and tube are exposed to the sudden thermal energy of a thermite reaction resulted in a hybrid reaction. The hybrid reaction of thermite and Si+C produced unique phases. X-ray diffraction pattern (XRD) as well as microstructural and elemental analyses are then investigated. XRD pattern showed formation of materials with possible electronic and magnetic properties. The cooling rate and the molten particle viscosity mathematical model of the process are meant to assist in understanding the physical and chemical phenomena took place during and after reaction. The results analysis revealed that up to 85% of materials converted into secondary products as ceramics-matrix composite. PMID:26641651

  3. Investigation of Embedded Si/C System Exposed to a Hybrid Reaction of Centrifugal-Assisted Thermite Method

    PubMed Central

    Mahmoodian, Reza; Yahya, Rosiyah; Dabbagh, Ali; Hamdi, Mohd; Hassan, Mohsen A.

    2015-01-01

    A novel method is proposed to study the behavior and phase formation of a Si+C compacted pellet under centrifugal acceleration in a hybrid reaction. Si+C as elemental mixture in the form of a pellet is embedded in a centrifugal tube. The pellet assembly and tube are exposed to the sudden thermal energy of a thermite reaction resulted in a hybrid reaction. The hybrid reaction of thermite and Si+C produced unique phases. X-ray diffraction pattern (XRD) as well as microstructural and elemental analyses are then investigated. XRD pattern showed formation of materials with possible electronic and magnetic properties. The cooling rate and the molten particle viscosity mathematical model of the process are meant to assist in understanding the physical and chemical phenomena took place during and after reaction. The results analysis revealed that up to 85% of materials converted into secondary products as ceramics-matrix composite. PMID:26641651

  4. 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

  5. Producing a trimethylpentanoic acid using hybrid polyketide synthases

    DOEpatents

    Katz, Leonard; Fortman, Jeffrey L; Keasling, Jay D

    2014-10-07

    The present invention provides for a polyketide synthase (PKS) capable of synthesizing trimethylpentanoic acid. The present invention also provides for a host cell comprising the PKS and when cultured produces the trimethylpentanoic acid. The present invention also provides for a method of producing the trimethylpentanoic acid, comprising: providing a host cell of the present invention, and culturing said host cell in a suitable culture medium such that the trimethylpentanoic acid is produced, optionally isolating the trimethylpentanoic acid, and optionally, reducing the isolated trimethylpentanoic acid into a trimethylpentanol or an iso-octane.

  6. An enzyme-free colorimetric assay using hybridization chain reaction amplification and split aptamers.

    PubMed

    Wang, Qing; Yang, Xiaohan; Yang, Xiaohai; Wang, Kemin; Zhang, Hua; Liu, Pei

    2015-11-21

    A novel unmodified gold nanoparticle (AuNP)-based colorimetric assay was demonstrated using split aptamers and the hybridization chain reaction (HCR) amplification strategy. Here, the aptamer was divided into a structure-switching hairpin probe (DNA probe H1 (or H1')) and a single-stranded probe (DNA probe H2 (or H2')). In the presence of the target, DNA probe H1 (or H1') could specifically capture the target with the assistance of DNA probe H2 (or H2') to form a stable complex. Subsequently, the hairpin structure of DNA probe H1 (or H1') was changed, and then a chain reaction of hybridization events between two other hairpin probes (H3 and H4) propagated, resulting in the formation of nicked double-helices. Since it was difficult for such nicked double-helices to inhibit salt-induced AuNP aggregation, a red-to-blue color change was observed. With the elegant amplification effect of HCR, this assay showed a low detection limit (15 nM for Hg(2+) and 1 ?M for adenosine), which was lower than or at least comparable to previous AuNP-based methods. The novel strategy not only eliminated the requirements of enzymatic reactions, separation processes, chemical modifications, and sophisticated instruments, but also could be used for other targets only by simply changing the DNA probe sequences. PMID:26442287

  7. Pseudolymphomatous reaction to varicella zoster virus vaccination: role of viral in situ hybridization.

    PubMed

    Porto, Dennis A; Comfere, Nneka I; Myers, Laura M; Abbott, Jared J

    2010-10-01

    Herpes zoster (shingles) is the result of a reactivation of the varicella zoster virus (VZV). Many adults obtain a VZV vaccine in order to prevent zoster. Non-specific injection site reactions and generalized herpes eruptions have been reported to occur, especially in immunocompromised patients. However, these are most often anatomically generalized reactions and histopathologically resemble typical herpes infections. We report a 61-year-old female on immunosuppressant medications for rheumatoid arthritis who presented with a subcutaneous nodule at the site of a recent herpes zoster vaccination. Histopathological examination revealed a dense nodular and interstitial mononuclear infiltrate throughout the mid and deep dermis with extension into the superficial subcutaneous fat. Immunohistochemical staining revealed an admixture of T-cells and B-cells, with a predominance of T-cells. These findings are consistent with a pseudolymphoma (PL), a reactive inflammatory disorder that can resemble cutaneous lymphoma and has rarely been described in herpes infections and post-herpetic scars. In situ hybridization studies for VZV were performed and highlighted occasional deep fibroblasts with nuclear positivity for VZV DNA. A review of post-vaccination reactions and herpes-related PL is discussed with emphasis on using in situ hybridization in establishing the diagnosis. PMID:19889051

  8. 40 CFR 721.9460 - Tall oil fatty acids, reaction products with polyamines, alkyl substituted.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9460 Tall oil fatty acids, reaction... reporting. (1) The chemical substance identified generically as tall oil fatty acids, reaction products with... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Tall oil fatty acids,...

  9. 40 CFR 721.9460 - Tall oil fatty acids, reaction products with polyamines, alkyl substituted.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9460 Tall oil fatty acids, reaction... reporting. (1) The chemical substance identified generically as tall oil fatty acids, reaction products with... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Tall oil fatty acids,...

  10. 40 CFR 721.9460 - Tall oil fatty acids, reaction products with polyamines, alkyl substituted.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9460 Tall oil fatty acids, reaction... reporting. (1) The chemical substance identified generically as tall oil fatty acids, reaction products with... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Tall oil fatty acids,...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9460 Tall oil fatty acids, reaction... reporting. (1) The chemical substance identified generically as tall oil fatty acids, reaction products with... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Tall oil fatty acids,...

  12. 40 CFR 721.9460 - Tall oil fatty acids, reaction products with polyamines, alkyl substituted.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9460 Tall oil fatty acids, reaction... reporting. (1) The chemical substance identified generically as tall oil fatty acids, reaction products with... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Tall oil fatty acids,...

  13. A highly sensitive aptasensor for OTA detection based on hybridization chain reaction and fluorescent perylene probe.

    PubMed

    Wang, Bin; Wu, Yuanya; Chen, Yanfen; Weng, Bo; Xu, Liqun; Li, Changming

    2016-07-15

    An optical aptasensor was developed for ultrasensitive detection of ochratoxin A (OTA) based on hybridization chain reaction (HCR) amplification strategy and fluorescent perylene probe (PAPDI)/DNA composites. Dendritic DNA concatamers were synthesized by HCR strategy and modified on magnetic nanoparticles through aptamer as medium. A large amount of PAPDI probe aggregated under the induction of DNA concatamers and caused fluorescence quenching. In the presence of OTA, the PAPDI/DNA composites were released from magnetic nanoparticles due to the strong affinity between aptamer and OTA. In ethanol, PAPDI monomers disaggregated and produced strong fluorescence. The present method displays excellent sensitivity and selectivity towards OTA. PMID:26938491

  14. Student Award Finalist: Transient Analysis of Pulsed Dry Methane Reforming in DBD-Catalyst Hybrid Reaction

    NASA Astrophysics Data System (ADS)

    Tamura, Keishiro; Kameshima, Seigo; Ishibashi, Yutaro; Mizukami, Ryo; Yamazaki, Takumi; Nozaki, Tomohiro

    2015-09-01

    Pulsed dry methane reforming in DBD-catalyst hybrid reaction was investigated. Optical emission spectroscopy was also employed for the better understanding of reaction mechanism for enhanced CH4 and CO2 conversion as well as carbon removal reaction. Strong emission from C2 high pressure Swan system was uniquely observed when the Boudouard reaction dominates the surface reaction: C2 molecules were selectively produced via vibrationally excited CO which is originated from the adsorbed carbon on the catalysts. Time dependent change in gas composition and optical emission profiles of CO Ångström and C2 high pressure Swan systems were correlated in a systematic and consistent manner, leading to the deep insight into the CH4 and CO2 activation mechanisms over solid catalysts. Moreover, individual contribution of radical injection and heat generated by DBD were investigated. The result clearly showed that the CH4 and CO2 conversion rates were increased essentially by the radical injection, not the thermal effect of DBD.

  15. A computational study of ultrafast acid dissociation and acid-base neutralization reactions. I. The model

    NASA Astrophysics Data System (ADS)

    Maurer, Patrick; Thomas, Vibin; Rivard, Ugo; Iftimie, Radu

    2010-07-01

    Ultrafast, time-resolved investigations of acid-base neutralization reactions have recently been performed using systems containing the photoacid 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) and various Brønsted bases. Two conflicting neutralization mechanisms have been formulated by Mohammed et al. [Science 310, 83 (2005)] and Siwick et al. [J. Am. Chem. Soc. 129, 13412 (2007)] for the same acid-base system. Herein an ab initio molecular dynamics based computational model is formulated, which is able to investigate the validity of the proposed mechanisms in the general context of ground-state acid-base neutralization reactions. Our approach consists of using 2,4,6-tricyanophenol (exp. pKa≅1) as a model for excited-state HPTS∗ (pKa≅1.4) and carboxylate ions for the accepting base. We employ our recently proposed dipole-field/quantum mechanics (QM) treatment [P. Maurer and R. Iftimie, J. Chem. Phys. 132, 074112 (2010)] of the proton donor and acceptor molecules. This approach allows one to tune the free energy of neutralization to any desired value as well as model initial nonequilibrium hydration effects caused by a sudden increase in acidity, making it possible to achieve a more realistic comparison with experimental data than could be obtained via a full-QM treatment of the entire system. It is demonstrated that the dipole-field/QM model reproduces correctly key properties of the 2,4,6-tricyanophenol acid molecule including gas-phase proton dissociation energies and dipole moments, and condensed-phase hydration structure and pKa values.

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

    NASA Astrophysics Data System (ADS)

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

    An innovative lead acid battery was 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.

  17. Room temperature, hybrid sodium-based flow batteries with multi-electron transfer redox reactions

    SciTech Connect

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

    2015-06-11

    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 multielectron transfer redox reactions per active ion and multiple active ions for catholytes has been demonstrated. Furthermore, the critical barriers to mature this new HNFBs have also been explored.

  18. 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)

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

    SciTech Connect

    Preda, N.; Rusen, E.; Musuc, A.; Enculescu, M.; Matei, E.; Marculescu, B.; Fruth, V.; Enculescu, I.

    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.

  20. 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

  1. 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 μM) 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 μM), 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

  2. Enhancement of hydroxyl radical generation in the Fenton reaction by alpha-hydroxy acid.

    PubMed

    Ali, M A; Konishi, T

    1998-09-01

    The effect of various organic acids on hydroxyl radical (.OH) generation in the Fenton reaction were examined by the ESR spin trapping technique, where 5,5-dimethyl-1-pyroline-N-nitroxide (DMPO) and alpha-phenyl-tert-butyl nitrone (PBN) were used as the spin trapping reagents. alpha-Hydroxy acids such as lactic acid, glycolic acid and 2-hydroxy isobutyric acid were found to markedly enhance .OH generation in the reaction. In contrast, beta-hydroxy acid, alpha-keto acid, esters of alpha-hydroxy acids, aldehydes and other straight chain organic acids had no such enhancing activity. alpha-Amino acids had also no enhancing effect. The results suggest that the alpha-hydroxy acid moiety is prerequisite for the enhancement of .OH generation in the Fenton reaction. Superoxide dismutase did not inhibit the enhancing effect of alpha-hydroxy acids whereas catalase completely inhibited the .OH generation. Thus, alpha-hydroxy acids directly enhanced the .OH generation via the Fenton reaction but not the Haber-Weiss reaction. Possible role of lactic acid manipulating .OH generation is discussed in relation to the ischemia-reperfusion cell damage. PMID:9784848

  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. 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.

  5. 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

  6. Demonstration of Imino Acids as Products of the Reactions Catalyzed by D- and L-Amino Acid Oxidases

    PubMed Central

    Hafner, Edmund W.; Wellner, Daniel

    1971-01-01

    It had long been thought, but never demonstrated, that imino acids are formed in the reactions catalyzed by D- and L-amino acid oxidases (EC 1.4.3.3 and 1.4.3.2). The formation of imino acids is now shown directly by allowing the amino acid oxidase reaction to proceed in the presence of NaBH4, when the imino acid is reduced to the corresponding racemic amino acid. Thus, when NaBH4 is added to a mixture of D-amino acid oxidase and D-alanine, a significant amount of L-alanine is formed. Analogous results are obtained using L-amino acid oxidase and L-leucine. Since D-amino acid oxidase is active in the presence of NaBH4, L-alanine continues to be formed until most of the D-isomer is oxidized by the enzyme. This reaction provides a new method for inverting the configuration of an amino acid. When NaBH4 is added to a system containing D-amino acid oxidase plus D-alanine and L-lysine, free ε-N-(1-carboxyethyl)-L-lysine is formed. When bovine serum albumin is substituted for L-lysine, the same compound results upon acid hydrolysis. It is concluded that the amino acid oxidase reaction produces a free imino acid, which may be reduced by NaBH4 to a racemic amino acid or may form Schiff's bases by reaction with the ε-amino groups of proteins and of free lysine. PMID:4396920

  7. 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

  8. Hybrid Fe3O4-Poly(acrylic acid) Nanogels for Theranostic Cancer Treatment.

    PubMed

    Chen, Ying; Nan, Jingya; Lu, Yue; Wang, Chunpeng; Chu, Fuxiang; Gu, Zhen

    2015-05-01

    Multifunctional nanomedicine integrated with both therapy and diagnostics holds vast potential in cancer treatment. We developed hybrid Fe3O4-poly(acrylic acid) (PAA) nanogels for both drug delivery and magnetic resonance imaging (MRI). Superparamagnetic Fe3O4 nanoparticles were encapsulated inside porous PAA nanogels via an in situ co-precipitation approach. With successive growth of magnetic nanoparticles, the highest magnetization saturation (M(s)) value of the Fe3O4 nanoparticles in the PAA nanogels was determined as 20 emu/g. The resulting hybrid Fe3O4-PAA nanogels showed high drug loading capacity (98%) and sustained drug release in vitro. Cytotoxicity assays and cellular imaging demonstrated that the hybrid nanogels were highly biocompatible and efficiently internalized in human neuroblastoma SH-SY5Y cells. In MRI studies, the hybrid nanogels exhibited an excellent contrast in T2 weighted imaging and a high MRI sensitivity in the tumor site. PMID:26349390

  9. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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).

  11. Photoluminescence and quantum yields of organic/inorganic hybrids prepared through formic acid solvolysis

    NASA Astrophysics Data System (ADS)

    Fu, Lianshe; Sá Ferreira, R. A.; Fernandes, M.; Nunes, S. C.; de Zea Bermudez, V.; Hungerford, Graham; Rocha, J.; Carlos, L. D.

    2008-03-01

    Three undoped di-urea cross-linked poly(oxyethylene) (POE)/siloxane hybrid matrices, classed as di-ureasils, incorporating POE segments with different lengths were prepared through the carboxylic acid solvolysis sol-gel method using formic acid. The resulting hybrids were characterized by X-ray diffraction, Fourier transform mid-infrared spectroscopy, 29Si and cross-polarization 13C magic-angle spinning nuclear magnetic resonance and photoluminescence spectroscopy. The hybrids' structure is essentially independent of the polymer chain length and the materials are room temperature white-light emitters with emission quantum yields of ˜10 ± 1% and lifetime average values between 2 and 4 ns. For the di-ureasil host with short polymer chains the solvolysis method favours the increase of the PL quantum yields relatively to conventional sol-gel route.

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

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Hydrofluoric acid, reaction...

  13. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hydrofluoric acid, reaction...

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hydrofluoric acid, reaction...

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Hydrofluoric acid, reaction...

  16. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Hydrofluoric acid, reaction...

  17. 40 CFR 721.4461 - Hydrofluoric acid, reaction products with octane (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Hydrofluoric acid, reaction...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Hydrofluoric acid, reaction...

  19. 40 CFR 721.10464 - Fatty acid, reaction products with alkanolamine (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10464 Fatty acid, reaction products with alkanolamine (generic). (a... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Fatty acid, reaction products...

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

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Hydrofluoric acid, reaction...

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

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4461 Hydrofluoric acid, reaction products with octane... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Hydrofluoric acid, reaction...

  2. 40 CFR 721.4385 - Hydrofluoric acid, reaction products with heptane.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4385 Hydrofluoric acid, reaction products with heptane. (a) Chemical... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Hydrofluoric acid, reaction...

  3. 40 CFR 721.10251 - Fatty acids, reaction products with alkanolamine (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10251 Fatty acids, reaction products with alkanolamine (generic). (a... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Fatty acids, reaction products...

  4. 40 CFR 721.10251 - Fatty acids, reaction products with alkanolamine (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10251 Fatty acids, reaction products with alkanolamine (generic). (a... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Fatty acids, reaction products...

  5. 40 CFR 721.10464 - Fatty acid, reaction products with alkanolamine (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10464 Fatty acid, reaction products with alkanolamine (generic). (a... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Fatty acid, reaction products...

  6. 40 CFR 721.10251 - Fatty acids, reaction products with alkanolamine (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10251 Fatty acids, reaction products with alkanolamine (generic). (a... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Fatty acids, reaction products...

  7. 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…

  8. 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

  9. 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…

  10. Highly sensitive electrochemical biosensor based on nonlinear hybridization chain reaction for DNA detection.

    PubMed

    Jia, Liping; Shi, Shanshan; Ma, Rongna; Jia, Wenli; Wang, Huaisheng

    2016-06-15

    In the present work we demonstrated an ultrasensitive detection platform for specific DNA based on nonlinear hybridization chain reaction (HCR) by triggering chain-branching growth of DNA dendrimers. HCR was initiated by target DNA (tDNA) and finally formed dendritic structure by self-assembly. The electrochemical signal was drastically enhanced by capturing multiple catalytic peroxidase with high-ordered growth. Electrochemical signals were obtained by measuring the reduction current of oxidized 3, 3', 5, 5'-tetramethylbenzidine sulfate (TMB), which was generated by HRP in the presence of H2O2. This method exhibited ultrahigh sensitivity to tDNA with detection limit of 0.4fM. Furthermore, the biosensor was also capable of discriminating single-nucleotide difference among concomitant DNA sequences. PMID:26872213

  11. Reprogrammable multiplexed detection of circulating oncomiRs using hybridization chain reaction.

    PubMed

    Rana, Muhit; Balcioglu, Mustafa; Kovach, Maya; Hizir, Mustafa Salih; Robertson, Neil M; Khan, Irfan; Yigit, Mehmet V

    2016-02-28

    In this study, we have coupled the DNA polymerization capability of hybridization chain reaction (HCR) with the plasmonic properties of gold nanoparticles to develop a reprogrammable and multiplexed detection of three circulating oncomiRs (miR-10b, miR-21 and miR-141) dysregulated in various disease states of breast cancer. We have demonstrated that by simply changing the initiator (label-free short single stranded DNA) content of the HCR, while keeping everything else unchanged, the same nanoparticle assembly can be reprogrammed for the detection of the target oncomiRs individually or simultaneously in all possible combinations. We have shown that as little as 20 femtomoles of each oncomiR can be detected visually without using any analytical instrument. Furthermore, we demonstrated that the target oncomiR can be detected in an RNA pool isolated from a liquid biopsy mimic of breast cancer. PMID:26839925

  12. Nucleic Acid Hybridization Studies within the Genus Cucurbita

    PubMed Central

    Goldberg, Robert B.; Bemis, William P.; Siegel, Albert

    1972-01-01

    The DNAs of Cucurbita species were examined by several methods. All Cucurbita DNAs have a similar CsCl isopycnic banding pattern consisting of a major band at 1.695 g/cc and a well separated satellite band at 1.707 g/cc. Compared to other plant and animal genera, Cucurbita species have a large genomic proportion of rDNA; this value ranging from 1.4% to 3.1%. The genomic proportion of rDNA was found not to be useful as a characteristic indicating degree of relatedness of the various Cucurbita species. However, Cucurbita DNAs can be distinguished by the extent to which their repetitive sequences cross-hybridize to each other and an assessment of species relationships can be made on this basis. PMID:17248582

  13. Reaction sequences in simulated neutralized current acid waste slurry during processing with formic acid

    SciTech Connect

    Smith, H.D.; Wiemers, K.D.; Langowski, M.H.; Powell, M.R.; Larson, D.E.

    1993-11-01

    The Hanford Waste Vitrification Plant (HWVP) is being designed for the Department of Energy to immobilize high-level and transuranic wastes as glass for permanent disposal. Pacific Northwest Laboratory is supporting the HWVP design activities by conducting laboratory-scale studies using a HWVP simulated waste slurry. Conditions which affect the slurry processing chemistry were evaluated in terms of offgas composition and peak generation rate and changes in slurry composition. A standard offgas profile defined in terms of three reaction phases, decomposition of H{sub 2}CO{sub 3}, destruction of NO{sub 2}{sup {minus}}, and production of H{sub 2} and NH{sub 3} was used as a baseline against which changes were evaluated. The test variables include nitrite concentration, acid neutralization capacity, temperature, and formic acid addition rate. Results to date indicate that pH is an important parameter influencing the N{sub 2}O/NO{sub x} generation ratio; nitrite can both inhibit and activate rhodium as a catalyst for formic acid decomposition to CO{sub 2} and H{sub 2}; and a separate reduced metal phase forms in the reducing environment. These data are being compiled to provide a basis for predicting the HWVP feed processing chemistry as a function of feed composition and operation variables, recommending criteria for chemical adjustments, and providing guidelines with respect to important control parameters to consider during routine and upset plant operation.

  14. Proton exchange in acid-base complexes induced by reaction coordinates with heavy atom motions

    NASA Astrophysics Data System (ADS)

    Alavi, Saman; Taghikhani, Mahdi

    2012-06-01

    We extend previous work on nitric acid-ammonia and nitric acid-alkylamine complexes to illustrate that proton exchange reaction coordinates involve the rocking motion of the base moiety in many double hydrogen-bonded gas phase strong acid-strong base complexes. The complexes studied involve the biologically and atmospherically relevant glycine, formic, acetic, propionic, and sulfuric acids with ammonia/alkylamine bases. In these complexes, the magnitude of the imaginary frequencies associated with the proton exchange transition states are <400 cm-1. This contrasts with widely studied proton exchange reactions between symmetric carboxylic acid dimers or asymmetric DNA base pair and their analogs where the reaction coordinate is localized in proton motions and the magnitude of the imaginary frequencies for the transition states are >1100 cm-1. Calculations on complexes of these acids with water are performed for comparison. Variations of normal vibration modes along the reaction coordinate in the complexes are described.

  15. 40 CFR 721.10428 - Fatty acids, C18-unsatd., dimers, reaction products with 1-piperazineethanamine.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., reaction products with 1-piperazineethanamine. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as fatty acids, C18-unsatd., dimers, reaction products with..., reaction products with 1-piperazineethanamine. 721.10428 Section 721.10428 Protection of...

  16. 40 CFR 721.9485 - Dimer acid/polymerized rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... reaction product (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as Dimer acid/polymerized rosin amidoamine reaction product (PMN... amidoamine reaction product (generic). 721.9485 Section 721.9485 Protection of Environment...

  17. 40 CFR 721.9485 - Dimer acid/polymerized rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... reaction product (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as Dimer acid/polymerized rosin amidoamine reaction product (PMN... amidoamine reaction product (generic). 721.9485 Section 721.9485 Protection of Environment...

  18. 40 CFR 721.9485 - Dimer acid/polymerized rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... reaction product (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as Dimer acid/polymerized rosin amidoamine reaction product (PMN... amidoamine reaction product (generic). 721.9485 Section 721.9485 Protection of Environment...

  19. 40 CFR 721.9485 - Dimer acid/polymerized rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... reaction product (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as Dimer acid/polymerized rosin amidoamine reaction product (PMN... amidoamine reaction product (generic). 721.9485 Section 721.9485 Protection of Environment...

  20. 40 CFR 721.9485 - Dimer acid/polymerized rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... reaction product (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as Dimer acid/polymerized rosin amidoamine reaction product (PMN... amidoamine reaction product (generic). 721.9485 Section 721.9485 Protection of Environment...

  1. 40 CFR 721.10428 - Fatty acids, C18-unsatd., dimers, reaction products with 1-piperazineethanamine.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., reaction products with 1-piperazineethanamine. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as fatty acids, C18-unsatd., dimers, reaction products with..., reaction products with 1-piperazineethanamine. 721.10428 Section 721.10428 Protection of...

  2. Donor–acceptor graphene-based hybrid materials facilitating photo-induced electron-transfer reactions

    PubMed Central

    Stergiou, Anastasios; Pagona, Georgia

    2014-01-01

    Summary Graphene research and in particular the topic of chemical functionalization of graphene has exploded in the last decade. The main aim is to increase the solubility and thereby enhance the processability of the material, which is otherwise insoluble and inapplicable for technological applications when stacked in the form of graphite. To this end, initially, graphite was oxidized under harsh conditions to yield exfoliated graphene oxide sheets that are soluble in aqueous media and amenable to chemical modifications due to the presence of carboxylic acid groups at the edges of the lattice. However, it was obvious that the high-defect framework of graphene oxide cannot be readily utilized in applications that are governed by charge-transfer processes, for example, in solar cells. Alternatively, exfoliated graphene has been applied toward the realization of some donor–acceptor hybrid materials with photo- and/or electro-active components. The main body of research regarding obtaining donor–acceptor hybrid materials based on graphene to facilitate charge-transfer phenomena, which is reviewed here, concerns the incorporation of porphyrins and phthalocyanines onto graphene sheets. Through illustrative schemes, the preparation and most importantly the photophysical properties of such graphene-based ensembles will be described. Important parameters, such as the generation of the charge-separated state upon photoexcitation of the organic electron donor, the lifetimes of the charge-separation and charge-recombination as well as the incident-photon-to-current efficiency value for some donor–acceptor graphene-based hybrids, will be discussed. PMID:25247140

  3. Donor-acceptor graphene-based hybrid materials facilitating photo-induced electron-transfer reactions.

    PubMed

    Stergiou, Anastasios; Pagona, Georgia; Tagmatarchis, Nikos

    2014-01-01

    Graphene research and in particular the topic of chemical functionalization of graphene has exploded in the last decade. The main aim is to increase the solubility and thereby enhance the processability of the material, which is otherwise insoluble and inapplicable for technological applications when stacked in the form of graphite. To this end, initially, graphite was oxidized under harsh conditions to yield exfoliated graphene oxide sheets that are soluble in aqueous media and amenable to chemical modifications due to the presence of carboxylic acid groups at the edges of the lattice. However, it was obvious that the high-defect framework of graphene oxide cannot be readily utilized in applications that are governed by charge-transfer processes, for example, in solar cells. Alternatively, exfoliated graphene has been applied toward the realization of some donor-acceptor hybrid materials with photo- and/or electro-active components. The main body of research regarding obtaining donor-acceptor hybrid materials based on graphene to facilitate charge-transfer phenomena, which is reviewed here, concerns the incorporation of porphyrins and phthalocyanines onto graphene sheets. Through illustrative schemes, the preparation and most importantly the photophysical properties of such graphene-based ensembles will be described. Important parameters, such as the generation of the charge-separated state upon photoexcitation of the organic electron donor, the lifetimes of the charge-separation and charge-recombination as well as the incident-photon-to-current efficiency value for some donor-acceptor graphene-based hybrids, will be discussed. PMID:25247140

  4. Phosphonic acid functionalized ordered mesoporous material: a new and ecofriendly catalyst for one-pot multicomponent Biginelli reaction under solvent-free conditions.

    PubMed

    Pramanik, Malay; Bhaumik, Asim

    2014-01-22

    We report a new ordered 2D hexagonal mesoporous organosilica material (PAFMS-1) bearing phosphonic acid functionality at the surface. This hybrid material showed high Brunauer-Emmett-Teller surface area (565 m(2) g(-1)) and ordered assembly of mesoporoes with an average pore diameter of ca. 2.1 nm. This novel hybrid mesoporous material has been synthesized via cocondensation of (triethoxysilyl)(propyliminomethyl)biphenylmethyl phosphoester (PEFOS) and tetraethyl orthosilicate (TEOS) in the presence of cationic surfactant cetyltrimethylammonium bromide (CTAB) at 373 K. The phosphoester-functionalized organosilane (PEFOS) precursor has been synthesized for the first time by a simple SN2 reaction followed by Suzuki coupling and a Mannich reaction. The material has been characterized by powder X-ray diffraction, N2 sorption, and transmission electron microscopy image analysis, whereas the presence of organic moieties (an aromatic biphenyl ring and an aliphatic side chain), phosphrous, and silicon in the pore wall of the material have been characterized by solid-state magic-angle-spinning NMR, X-ray photoelectron, and Fourier transform infrared (FT-IR) spectroscopic tools. Further, the surface acid strength of the hybrid material has been determined by FT-IR analysis of the samples via temperature-programmed pyridine adsorption studies. The material has been utilized as a reusable heterogeneous catalyst for the synthesis of biologically important and value added multifunctionalized 3,4-dihydropyridin-2-1H-(ones)/3,4-dihydropyridin-2-1H-(thiones) (DHPMs) through a multicomponent Biginelli condensation reaction under solvent-free conditions at 333 K. The phosphonic acid functionalized 2D hexagonal mesoporous material showed much higher catalytic activity in this multicomponent condensation reaction over sulfonic acid functionalized mesoporous silica (MCM-41-SO3H) bearing an aliphatic chain in the hybrid framework. PMID:24372168

  5. 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%.

  6. HONO Reactions on Clean and Nitric Acid Doped Glass Surfaces

    NASA Astrophysics Data System (ADS)

    Syomin, D.; Ramazan, K. A.; Finlayson-Pitts, B. J.

    2002-12-01

    It is well known that HONO, NO and HNO3 are the major products of the heterogeneous hydrolysis of NO2. However, studies of NO2 hydrolysis in laboratory systems are complicated by secondary reactions of HONO occurring on the glass walls of the reactor. These reactions affect the rate of HONO formation at the beginning of the reaction as well as at longer reaction times. We investigated reactions of HONO on clean and HNO3 predosed silica surfaces. In order to investigate the kinetics and mechanism of these surface reactions the rate of dark decay of HONO was studied in a long path IR borosilicate glass cell at different initial HONO concentrations and relative humidities. Observed loss of HONO and production of the gas phase species were interpreted using a computer kinetics model of this system. The mechanism and the implications of the removal of HONO from the atmosphere are discussed.

  7. Effective molarity in a nucleic acid-controlled reaction.

    PubMed

    Catalano, Michael J; Price, Nathan E; Gates, Kent S

    2016-06-01

    Positioning of reactive functional groups within a DNA duplex can enable chemical reactions that otherwise would not occur to an appreciable extent. However, few studies have quantitatively defined the extent to which the enforced proximity of reaction partners in duplex DNA can favor chemical processes. Here, we measured substantial effective molarities (as high as 25M) afforded by duplex DNA to a reaction involving interstrand cross-link formation between 2'-deoxyadenosine and a 2-deoxyribose abasic (Ap) site. PMID:27117430

  8. 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.

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

    NASA Astrophysics Data System (ADS)

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

    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 that the combination of lead-acid batteries and PEMFC shows advantages in case of applications with high peak power requirements (i.e. electric scooter) and applications where the fuel cell is used as auxiliary power supply to recharge the battery. The high efficiency of fuel cells at partial load operation results in a good fuel economy for recharging of lead-acid batteries with a fuel cell system.

  10. Field and Laboratory Studies of Reactions between Atmospheric Water Soluble Organic Acids and Inorganic Particles

    SciTech Connect

    Wang, Bingbing; Kelly, Stephen T.; Sellon, Rachel E.; Shilling, John E.; Tivanski, Alexei V.; Moffet, Ryan C.; Gilles, Mary K.; Laskin, Alexander

    2013-06-25

    Atmospheric inorganic particles undergo complex heterogeneous reactions that change their physicochemical properties. Depletion of chloride in sea salt particles was reported in previous field studies and was attributed to the acid displacement of chlorides with inorganic acids, such as nitric and sulfuric acids [1-2]. Recently, we showed that NaCl can react with water soluble organic acids (WSOA) and release gaseous hydrochloric acid (HCl) resulting in formation of organic salts [3]. A similar mechanism is also applicable to mixed WSOA/nitrate particles where multi-phase reactions are driven by the volatility of nitric acid. Furthermore, secondary organic material, which is a complex mixture of carboxylic acids, exhibits the same reactivity towards chlorides and nitrates. Here, we present a systematic study of reactions between atmospheric relevant WSOA, SOM, and inorganic salts including NaCl, NaNO3, and Ca(NO3)2 using complementary micro-spectroscopy analysis.

  11. Oxidation reaction of high molecular weight carboxylic acids in supercritical water.

    PubMed

    Jin, Fangming; Moriya, Takehiko; Enomoto, Heiji

    2003-07-15

    Stearic acid, being a model compound of high molecular weight carboxylic acids, was oxidized in a batch reactor by changing the oxygen supply with an insufficient oxygen supply at a constant reaction time at 420 degrees C. On the basis of the intermediate products identified by GC/MS, NMR, and HPLC analyses and the free-radical reaction mechanism, the oxidation pathways of high molecular weight carboxylic acids in supercritical water are discussed. The reaction of carboxylic acids in supercritical water proceeds with the consecutive oxidation of higher molecular weight carboxylic acids to lower molecular weight carboxylic acids through several major pathways. The attack of the hydroxyl radical occurs not only at the carbons in alpha-, beta-, gamma-positions to a --COOH group but also at the carbons ((omega-1)-carbon and/or omega-carbon) far in the alkyl chain from a --COOH group, which may lead to the formation of dicarboxylic acids. PMID:12901673

  12. Production of lactic acid from C6-polyols by alkaline hydrothermal reactions

    NASA Astrophysics Data System (ADS)

    Zhou, Huazhen; Jin, Fangming; Wu, Bing; Cao, Jianglin; Duan, Xiaokun; Kishita, Atsushi

    2010-03-01

    Production of lactic acid from C6-polyols (Mannitol) under alkaline hydrothermal conditions was investigated. Experiments were performed to examine the difference in the production of lactic acid between C6-polyols and C3-polyols (glycerine), as well as C6-aldoses (glucose). Results showed that the yield of lactic acid from C6-polyols was lower than that from both glycerine and glucose. It indicated that long chain polyols might follow a different reaction pathway from that of glycerine. Further investigation is needed to clarify the reaction mechanism and improve the relatively low lactic acid acid yield from C6-polyols.

  13. Advanced bipolar lead-acid battery for hybrid electric vehicles

    NASA Astrophysics Data System (ADS)

    Saakes, Michel; Kleijnen, Christian; Schmal, Dick; ten Have, Peter

    A large size 80 V bipolar lead acid battery was constructed and tested successfully with a drive cycle especially developed for a HEV. The bipolar battery was made using the bipolar plate developed at TNO and an optimised paste developed by Centurion. An empirical model was derived for calculating the Ragone plot from the results from a small size 12 V bipolar lead-acid battery. This resulted in a specific power of 340 W/kg for the 80 V module. The Ragone plot was calculated at t=5 and t=10 s after the discharge started for current densities varying from 0.02 to 1.2 A/cm 2. A further development of the bipolar lead-acid battery will result in a specific power of 500 W/kg or more. From the economic analysis we estimate that the price of this high power battery will be in the order of 500 US$/kWh. This price is substantially lower than for comparable high power battery systems. This makes it an acceptable candidate future for HEV.

  14. Process for chemical reaction of amino acids and amides yielding selective conversion products

    DOEpatents

    Holladay, Jonathan E.

    2006-05-23

    The invention relates to processes for converting amino acids and amides to desirable conversion products including pyrrolidines, pyrrolidinones, and other N-substituted products. L-glutamic acid and L-pyroglutamic acid provide general reaction pathways to numerous and valuable selective conversion products with varied potential industrial uses.

  15. Microfluidic platform for isolating nucleic acid targets using sequence specific hybridization

    PubMed Central

    Wang, Jingjing; Morabito, Kenneth; Tang, Jay X.; Tripathi, Anubhav

    2013-01-01

    The separation of target nucleic acid sequences from biological samples has emerged as a significant process in today's diagnostics and detection strategies. In addition to the possible clinical applications, the fundamental understanding of target and sequence specific hybridization on surface modified magnetic beads is of high value. In this paper, we describe a novel microfluidic platform that utilizes a mobile magnetic field in static microfluidic channels, where single stranded DNA (ssDNA) molecules are isolated via nucleic acid hybridization. We first established efficient isolation of biotinylated capture probe (BP) using streptavidin-coated magnetic beads. Subsequently, we investigated the hybridization of target ssDNA with BP bound to beads and explained these hybridization kinetics using a dual-species kinetic model. The number of hybridized target ssDNA molecules was determined to be about 6.5 times less than that of BP on the bead surface, due to steric hindrance effects. The hybridization of target ssDNA with non-complementary BP bound to bead was also examined, and non-specific hybridization was found to be insignificant. Finally, we demonstrated highly efficient capture and isolation of target ssDNA in the presence of non-target ssDNA, where as low as 1% target ssDNA can be detected from mixture. The microfluidic method described in this paper is significantly relevant and is broadly applicable, especially towards point-of-care biological diagnostic platforms that require binding and separation of known target biomolecules, such as RNA, ssDNA, or protein. PMID:24404041

  16. Degradation of Acid Orange 7 Dye in Two Hybrid Plasma Discharge Reactors

    NASA Astrophysics Data System (ADS)

    Shen, Yongjun; Lei, Lecheng; Zhang, Xingwang; Ding, Jiandong

    2014-11-01

    To get an optimized pulsed electrical plasma discharge reactor and to increase the energy utilization efficiency in the removal of pollutants, two hybrid plasma discharge reactors were designed and optimized. The reactors were compared via the discharge characteristics, energy transfer efficiency, the yields of the active species and the energy utilization in dye wastewater degradation. The results showed that under the same AC input power, the characteristics of the discharge waveform of the point-to-plate reactor were better. Under the same AC input power, the two reactors both had almost the same peak voltage of 22 kV. The peak current of the point-to-plate reactor was 146 A, while that of the wire-to-cylinder reactor was only 48.8 A. The peak powers of the point-to-plate reactor and the wire-to-cylinder reactor were 1.38 MW and 1.01 MW, respectively. The energy per pulse of the point-to-plate reactor was 0.2221 J, which was about 29.4% higher than that of the wire-to-cylinder reactor (0.1716 J). To remove 50% Acid Orange 7 (AO7), the energy utilizations of the point-to-plate reactor and the wire-to-cylinder reactor were 1.02 × 10-9 mol/L and 0.61 × 10-9 mol/L, respectively. In the point-to-plate reactor, the concentration of hydrogen peroxide in pure water was 3.6 mmol/L after 40 min of discharge, which was higher than that of the wire-to-cylinder reactor (2.5 mmol/L). The concentration of liquid phase ozone in the point-to-plate reactor (5.7 × 10-2 mmol/L) was about 26.7% higher than that in the wire-to-cylinder reactor (4.5 × 10-2 mmol/L). The analysis results of the variance showed that the type of reactor and reaction time had significant impacts on the yields of the hydrogen peroxide and ozone. The main degradation intermediates of AO7 identified by gas chromatography and mass spectrometry (GCMS) were acetic acid, maleic anhydride, p-benzoquinone, phenol, benzoic acid, phthalic anhydride, coumarin and 2-naphthol. Proposed degradation pathways were elucidated in light of the analyzed degradation products.

  17. 5-Florouracil-loaded poly(lactic acid)-poly(caprolactone) hybrid scaffold: potential chemotherapeutic implant.

    PubMed

    Gupta, Kamal K; Pal, Namrata; Mishra, Pradeep K; Srivastava, Pradeep; Mohanty, Sujata; Maiti, Pralay

    2014-08-01

    Hybrid nanofibers of poly(lactic acid) and polycaprolactone have been developed by embedding cancerous drug through electrospinning technique. The composition of polymer has been varied to check the compositional effect on properties. The quality of nanofibers has been testified through surface morphology, wetting properties using contact angle and mechanical strength under uniaxial elongation. The compatibility of drug (5-fluorourasil) with matrix fiber has been verified using Fourier transform infrared, X-ray diffraction, Raman spectroscopy, and differential scanning calorimetry. The drug release study has been performed showing greater release in hybrid fibers when compared with pure polymers as a result of synergism of two immiscible polymers and quasi-Fickian diffusion mechanism in hybrid nanofiber as implants showing compositional effect on drug release. A model has been proposed showing faster release of drugs in hybrid systems. Biological responses through fluorescence imaging and MTT assay confirm the release of drug from hybrid nanofibers showing potential use of hybrid scaffolds as chemotherapeutic implant. PMID:24038786

  18. 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

  19. Room temperature, hybrid sodium-based flow batteries with multi-electron transfer redox reactions

    DOE PAGESBeta

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

    2015-06-11

    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 volumemore » of the molten Na alloy can be used with a limited ion-exchange membrane size. In this proof-of-concept study, the feasibility of multielectron transfer redox reactions per active ion and multiple active ions for catholytes has been demonstrated. Furthermore, the critical barriers to mature this new HNFBs have also been explored.« less

  20. Combinatorial analysis of mRNA expression patterns in mouse embryos using hybridization chain reaction.

    PubMed

    Huss, David; Choi, Harry M T; Readhead, Carol; Fraser, Scott E; Pierce, Niles A; Lansford, Rusty

    2015-03-01

    Multiplexed fluorescent hybridization chain reaction (HCR) and advanced imaging techniques can be used to evaluate combinatorial gene expression patterns in whole mouse embryos with unprecedented spatial resolution. Using HCR, DNA probes complementary to mRNA targets trigger chain reactions in which metastable fluorophore-labeled DNA HCR hairpins self-assemble into tethered fluorescent amplification polymers. Each target mRNA is detected by a probe set containing one or more DNA probes, with each probe carrying two HCR initiators. For multiplexed experiments, probe sets for different target mRNAs carry orthogonal initiators that trigger orthogonal DNA HCR amplification cascades labeled by spectrally distinct fluorophores. As a result, in situ amplification is performed for all targets simultaneously, and the duration of the experiment is independent of the number of target mRNAs. We have used multiplexed fluorescent in situ HCR and advanced imaging technologies to address questions of cell heterogeneity and tissue complexity in craniofacial patterning and anterior neural development. In the sample protocol presented here, we detect three different mRNA targets: Tg(egfp), encoding the enhanced green fluorescent protein (GFP) transgene (typically used as a control); Twist1, encoding a transcription factor involved in cell lineage determination and differentiation; and Pax2, encoding a transcription factor expressed in the mid-hindbrain region of the mouse embryo. PMID:25734068

  1. Synthesis and solvent-dependent photochromic reactions of porphyrin-spiropyran hybrid compounds

    NASA Astrophysics Data System (ADS)

    Hur, Dae Young; Park, Tae Jong; Shin, Eun Ju

    2014-01-01

    Porphyrin(Por)-spiropyran(SP) hybrid compounds, including Por-SP dyad, Por-SP2 triad, and Por-SP4 pentad, were prepared and characterized by 1H NMR, MALDI-TOF MS and UV-Vis spectroscopies. Upon 350 nm UV irradiation of Por-SPn (n = 1, 2, 4) in dichloromethane, unusual red-shifted absorption spectra were observed with the colour change from pink into green. Probably due to the protonation of core nitrogens in porphyrin ring, their absorption maxima in dichloromethane were shifted from 418 (Soret band), 515, 550, 590, 645 (four Q bands) nm into 450 and 665 nm. Also, fluorescence maxima were also shifted from 650 and 715 nm to 692 nm. In the other hands, upon irradiation with 350 nm UV light in THF, the colour changed from pink into violet and absorption band at 590 nm increased and the fluorescence spectra showed the decrease of 650 and 715 nm bands and increase of 600-640 nm band, due to the normal ring-opening reaction of spiropyran moiety into merocyanine. In the dark, original absorption and fluorescence spectra were recovered very slowly in dichloromethane, but quickly in THF. The reversible photochromic reactions of Por-SPn (n = 1, 2, 4) in dichloromethane and THF were investigated by observing absorption and fluorescence spectral changes during UV irradiation or standing in the dark.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    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.

  3. 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

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

    SciTech Connect

    Xu, Zhenli; Cai, Wei; Cheng, Xiaolin

    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.

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

    PubMed

    O'Coinceanainn, M; Hynes, M J

    2001-03-01

    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 degrees 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 reaction of [Al(H2O)5OH]2+ with the ligands. [Al(H2O)5OH]2+ reacts with gallic acid, gallic acid methyl ester and adrenaline with rate constants of 1145, 1330 and 316 M(-1) s(-1) respectively. These data together with the equilibrium data enable the rate constants for reaction of [Al(H2O)6]3+ with both gallic acid and gallic acid methyl ester to be calculated. In view of the dissociative nature of water exchange on [Al(H2O)6]3+ and [Al(H2O)5(OH)]2+ the complex formation rate constants are discussed in terms of the Eigen-Wilkins-Tamm mechanism. The overall mechanisms have been validated using global analysis. The results are compared with previously published data on the complex formation reactions of aluminium(III). In addition, the rate constants and mechanisms for replacement of maltol by gallic acid methyl ester and diethylenetriaminepentaacetic acid (dtpa) have been investigated. PMID:11330467

  6. Compatible Mechanism for a Simultaneous Description of the Roebuck, Dushman, and Iodate-Arsenous Acid Reactions in an Acidic Medium.

    PubMed

    Valkai, László; Horváth, Attila K

    2016-02-15

    The iodine-arsenous acid (Roebuck), iodide-iodate (Dushman), and iodate-arsenous acid reactions have been studied simultaneously by a stopped-flow technique by monitoring the absorbance-time profiles at the isosbestic point of the I2/I3(-) system (468 nm). Using the well-accepted rate coefficients of iodine hydrolysis, we have proven that iodine is the kinetically active species of the iodine-arsenous acid reaction. Strong iodide inhibition of this system is explained by a rapidly established equilibrium between iodine and arsenous acid to produce an iodide ion, a hydrogen ion, and a short-lived intermediate H2AsO3I, which is shifted far to the left. Taking into consideration the generally accepted kinetic model of the Dushman reaction where I2O2 plays a key role to account for all of the most important observations in this subsystem and a sequence of simple formal oxygen-transfer reactions between arsenous acid and iodic acid as well as iodous acid and hypoiodous acid, we propose a 13-step comprehensive kinetic model, including seven rapidly established equilibria with only six fitted parameters, that is able to explain all of the most important characteristics of the kinetic curves of all of the title systems both individually and simultaneously. PMID:26838551

  7. Asymmetric Lewis acid organocatalysis of the Diels-Alder reaction by a silylated C-H acid.

    PubMed

    Gatzenmeier, Tim; van Gemmeren, Manuel; Xie, Youwei; Höfler, Denis; Leutzsch, Markus; List, Benjamin

    2016-02-26

    Silylium ion equivalents have shown promise as Lewis acid catalysts for a range of important C-C bond-forming reactions. Here we describe chiral C-H acids that upon in situ silylation, generate silylium-carbanion pairs, which are extremely active Lewis acid catalysts for enantioselective Diels-Alder reactions of cinnamates with cyclopentadiene. Enantiomeric ratios of up to 97:3 and diastereomeric ratios of more than 20:1 are observed across a diverse set of substitution patterns with 1 mole percent (mol %) of C-H acid catalyst and 10 mol % of a silylating reagent. The results show promise for broad applications of such C-H acid-derived silylium ion equivalents in asymmetric Lewis acid catalysis. PMID:26917765

  8. Optimization of dicarboxylic acid cellulose synthesis: reaction stoichiometry and role of hypochlorite scavengers.

    PubMed

    Sirviö, Juho Antti; Liimatainen, Henrikki; Visanko, Miikka; Niinimäki, Jouko

    2014-12-19

    The reaction conditions in terms of reaction time, sodium chlorite stoichiometry, and the effect of hypochlorite scavengers on the chlorite oxidation of dialdehyde cellulose (DAC) was studied. The impact of storage on the reactivity of DAC fibers was also investigated. It was found that chlorite oxidation of DAC is a rapid reaction, resulting in oxidation of 71% of the aldehyde after only 8 min when 2.5 times excess of sodium chlorite compared to aldehyde groups was used. Reactivity of DAC was observed to decrease quickly during the storage and only 68% of the aldehyde groups reacted after two weeks storage compared to the reaction performed with freshly prepared DAC. Hydrogen peroxide and sulfamic acid were observed to increase the reaction efficiency of chlorite oxidation by reducing the amount of side-reactions between chlorite and hypochlorite. A minor amount of sulfamic acid can be used to replace acetic acid as a catalyst. PMID:25263866

  9. 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...

  10. A novel biocompatible hyaluronic acid-chitosan hybrid hydrogel for osteoarthrosis therapy.

    PubMed

    Kaderli, S; Boulocher, C; Pillet, E; Watrelot-Virieux, D; Rougemont, A L; Roger, T; Viguier, E; Gurny, R; Scapozza, L; Jordan, O

    2015-04-10

    A conventional therapy for the treatment of osteoarthrosis is intra-articular injection of hyaluronic acid, which requires repeated, frequent injections. To extend the viscosupplementation effect of hyaluronic acid, we propose to associate it with another biopolymer in the form of a hybrid hydrogel. Chitosan was chosen because of its structural similarity to synovial glycosaminoglycans, its anti-inflammatory effects and its ability to promote cartilage growth. To avoid polyelectrolyte aggregation and obtain transparent, homogeneous gels, chitosan was reacetylated to a 50% degree, and different salts and formulation buffers were investigated. The biocompatibility of the hybrid gels was tested in vitro on human arthrosic synoviocytes, and in vivo assessments were made 1 week after subcutaneous injection in rats and 1 month after intra-articular injection in rabbits. Hyaluronic acid-chitosan polyelectrolyte complexes were prevented by cationic complexation of the negative charges of hyaluronic acid. The different salts tested were found to alter the viscosity and thermal degradation of the gels. Good biocompatibility was observed in rats, although the calcium-containing formulation induced calcium deposits after 1 week. The sodium chloride formulation was further tested in rabbits and did not show acute clinical signs of pain or inflammation. Hybrid HA-Cs hydrogels may be a valuable alternative viscosupplementation agent. PMID:25666331

  11. Comparison of dot blot hybridization, polymerase chain reaction, and virus isolation for detection of bovine herpesvirus-1 (BHV-1) in artificially infected bovine semen.

    PubMed Central

    Xia, J Q; Yason, C V; Kibenge, F S

    1995-01-01

    Bovine semen samples spiked with bovine herpesvirus 1 (BHV-1) were used to compare dot blot hybridization, polymerase chain reaction (PCR), and virus isolation for detection of BHV-1 in bovine semen. The PCR amplification used primers targeting the BHV-1 thymidine kinase gene and a nucleic acid releasing cocktail (GeneReleaser); the PCR product was used as the DNA probe in dot blot hybridization; virus isolation was done in primary bovine fetal testis (BFT) cell cultures. Semen diluted 1:20 in tissue culture medium had the least cytotoxicity and inhibition of viral cytopathic effects in BFT cells, allowing detection of 1 TCID50/100 microL of BHV-1 suspension by virus isolation. The presence of foreign DNA such as bovine sperm DNA or salmon sperm DNA increased the sensitivity of dot blot hybridization in detecting BHV-1, allowing detection of 20,000 TCID50/100 microL of neat semen. The inhibition of PCR amplification of BHV-1 DNA in bovine semen was eliminated by diluting the samples 1:20 in tissue culture medium. The best PCR amplification was obtained when semen was diluted 1:20 and when a reaction buffer of pH 9.0, with 1.0 mM MgCl2 was used. Under these conditions, the PCR followed by ethidium bromide staining of agarose gels could detect 1 TCID20/100 microL of sample, whereas PCR followed by Southern blot hybridization could detect 0.01 TCID50/100 microL of sample.(ABSTRACT TRUNCATED AT 250 WORDS) Images Fig. 1. Fig. 2. Fig. 3. PMID:7648521

  12. Nucleic Acid Polymerases of the Developing Chicken Embryo: A DNA Polymerase Preferring a Hybrid Template*

    PubMed Central

    Stavrianopoulos, Jannis G.; Karkas, John D.; Chargaff, Erwin

    1971-01-01

    This paper presents a preliminary survey of the nucleic acid polymerases of the developing chicken embryo, especially of the 4-day stage. The predominant activity is that of a DNA polymerase preferring a DNA-RNA hybrid as the template. The enzyme, which is activated by Mn2+ ions and inhibited by p-chloromercuriphenylsulfonate, copies preferentially the ribo strand of a hybrid, such as poly(rA)poly(dT), but is relatively inactive with all-ribo duplexes. DNA polymerase I of Escherichia coli was also found to use the hybrid template with high efficiency, copying preferentially the ribo strand. With the chicken enzyme, the template activity of denatured DNA was increased tenfold by simultaneous transcription with RNA polymerase. DNA polymerase activity reaches a maximum in the 6- to 8-day chicken embryo and then declines progressively to about one-third of the maximal value in the adult chicken. PMID:4943793

  13. Design of chiral urea-quaternary ammonium salt hybrid catalysts for asymmetric reactions of glycine Schiff bases†

    PubMed Central

    Tiffner, Maximilian; Novacek, Johanna; Busillo, Alfonso; Gratzer, Katharina; Massa, Antonio; Waser, Mario

    2015-01-01

    Bifunctional chiral urea-containing quaternary ammonium salts can be straightforwardly synthesised in good yield and with high structural diversity via a scalable and operationally simple highly telescoped sequence starting from trans-1,2-cyclohexanediamine. These novel hybrid catalysts were systematically investigated for their potential to control glycine Schiff bases in asymmetric addition reactions. It was found that Michael addition reactions and the herein presented aldol-initiated cascade reaction can be carried out to provide enantiomeric ratios up to 95 : 5 and good yields under mild conditions at room temperature. PMID:26504516

  14. Reactions of polyhalogenofunctional compounds with metals and electrophilic reagents. IX. Reaction of dichlorinated aldehydes with zinc and acid chlorides

    SciTech Connect

    Shchepin, V.V.; Fotin, V.V.; Sinani, S.V.; Mustafaeva, G.V.

    1988-07-10

    The authors studied the reaction of geminal dichloro-substituted aldehydes with zinc and acid and chlorides in aprotic solvents. As found, 2,2-dichlorobutanal and 2,2-dichloro-3-methylbutanal react vigorously with zinc and aliphatic or aromatic acid chlorides in an ether-ethyl acetate or ether-hexamethylphosphorotriamide system with the formation of the O-acylation products 2-chloro-1-acyloxybutenes with yields of 63-90%. The process is evidently based on the preferential attack by the hard electrophile (the acylium cation of the acid chloride) on the relatively hard nucleophilic center of the intermediately formed ambident organozinc compound, and it is this which determines the high regioselectivity of the reaction.

  15. Utilizing Intrinsic Properties of Polyaniline to Detect Nucleic Acid Hybridization through UV-Enhanced Electrostatic Interaction.

    PubMed

    Sengupta, Partha Pratim; Gloria, Jared N; Amato, Dahlia N; Amato, Douglas V; Patton, Derek L; Murali, Beddhu; Flynt, Alex S

    2015-10-12

    Detection of specific RNA or DNA molecules by hybridization to "probe" nucleic acids via complementary base-pairing is a powerful method for analysis of biological systems. Here we describe a strategy for transducing hybridization events through modulating intrinsic properties of the electroconductive polymer polyaniline (PANI). When DNA-based probes electrostatically interact with PANI, its fluorescence properties are increased, a phenomenon that can be enhanced by UV irradiation. Hybridization of target nucleic acids results in dissociation of probes causing PANI fluorescence to return to basal levels. By monitoring restoration of base PANI fluorescence as little as 10(-11) M (10 pM) of target oligonucleotides could be detected within 15 min of hybridization. Detection of complementary oligos was specific, with introduction of a single mismatch failing to form a target-probe duplex that would dissociate from PANI. Furthermore, this approach is robust and is capable of detecting specific RNAs in extracts from animals. This sensor system improves on previously reported strategies by transducing highly specific probe dissociation events through intrinsic properties of a conducting polymer without the need for additional labels. PMID:26388289

  16. Characterization of rapidly labelled ribonucleic acid in Escherichia coli by deoxyribonucleic acid–ribonucleic acid hybridization

    PubMed Central

    Pigott, G. H.; Midgley, J. E. M.

    1968-01-01

    1. Rapidly labelled RNA from Escherichia coli K 12 was characterized by hybridization to denatured E. coli DNA on cellulose nitrate membrane filters. The experiments were designed to show that, if sufficient denatured DNA is offered in a single challenge, practically all the rapidly labelled RNA will hybridize. With the technique employed, 75–80% hybridization efficiency could be obtained as a maximum. Even if an excess of DNA sites were offered, this value could not be improved upon in any single challenge of rapidly labelled RNA with denatured E. coli DNA. 2. It was confirmed that the hybridization technique can separate the rapidly labelled RNA into two fractions. One of these (30% of the total) was efficiently hybridized with the low DNA/RNA ratio (10:1, w/w) used in tests. The other fraction (70% of the total) was hybridized to DNA at low efficiencies with the DNA/RNA ratio 10:1, and was hybridized progressively more effectively as the amount of denatured DNA was increased. A practical maximum of 80% hybridization of all the rapidly labelled RNA was first achieved at a DNA/RNA ratio 210:1 (±10:1). This fraction was fully representative of the rapidly labelled RNA with regard to kind and relative amount of materials hybridized. 3. In competition experiments, where additions were made of unlabelled RNA prepared from E. coli DNA, DNA-dependent RNA polymerase (EC 2.7.7.6) and nucleoside 5′-triphosphates, the rapidly labelled RNA fraction hybridized at a low (10:1) DNA/RNA ratio was shown to be competitive with a product from genes other than those responsible for ribosomal RNA synthesis and thus was presumably messenger RNA. At higher DNA/rapidly labelled RNA ratios (200:1), competition with added unlabelled E. coli ribosomal RNA (without messenger RNA contaminants) lowered the hybridization of the rapidly labelled RNA from its 80% maximum to 23%. This proportion of rapidly labelled RNA was not competitive with E. coli ribosomal RNA even when the latter was in large excess. The ribosomal RNA would also not compete with the 23% rapidly labelled RNA bound to DNA at low DNA/RNA ratios. It was thus demonstrated that the major part of E. coli rapidly labelled RNA (70%) is ribosomal RNA, presumably a precursor to the RNA in mature ribosomes. 4. These studies have shown that, when earlier workers used low DNA/RNA ratios (about 10:1) in the assay of messenger RNA in bacterial rapidly labelled RNA, a reasonable estimate of this fraction was achieved. Criticisms that individual messenger RNA species may be synthesized from single DNA sites in E. coli at rates that lead to low efficiencies of messenger RNA binding at low DNA/RNA ratios are refuted. In accordance with earlier results, estimations of the messenger RNA content of E. coli in both rapidly labelled and randomly labelled RNA show that this fraction is 1·8–1·9% of the total RNA. This shows that, if any messenger RNA of relatively long life exists in E. coli, it does not contribute a measurable weight to that of rapidly labelled messenger RNA. PMID:4881972

  17. Effects of novel hybrids of caffeic acid phenethyl ester and NSAIDs on experimental ocular inflammation.

    PubMed

    Pittal, Valeria; Salerno, Loredana; Romeo, Giuseppe; Siracusa, Maria Angela; Modica, Maria Nunziata; Romano, Giovanni Luca; Salomone, Salvatore; Drago, Filippo; Bucolo, Claudio

    2015-04-01

    In this study, we report the design and synthesis of novel hybrids of caffeic acid phenetyl ester (CAPE) and non-steroidal anti-inflammatory drugs (NSAIDs). We assessed their effects on an experimental ocular inflammation in New Zealand rabbits. The formulations of CAPE-aspirin and CAPE-indomethacin hybrids were topical instilled in the rabbit?s eye. Afterwards, the anti-inflammatory activity was evaluated by grading the clinical signs and by assessing the inflammatory cell count, protein, PGE2 and TNF? levels in the aqueous humor. Furthermore, ocular tolerability of hybrids formulations was evaluated in a separate set of animals by using a modified Draize test. The ocular inflammation in the control group was significantly higher than in both the hybrid-treated groups, as indicated by clinical grading and biomarkers assessment. However, only the CAPE-aspirin hybrid reduced, in a significant dose-dependent manner, the ocular inflammation elicited by paracentesis. CAPE-indomethacin hybrid was able to significantly attenuate the clinical grading and the PGE2 aqueous levels only at the highest dose (0.1%). CAPE-aspirin significantly reduced PGE2 and TNF? levels in the aqueous humor as well as proteins and PMNs. Finally, all formulations showed no ocular irritation compared with vehicle-treated group. In conclusion, CAPE-aspirin shows full anti-inflammatory efficacy in experimental model of ocular inflammation demonstrating an optimal pharmacological and safety profile. Taken together these data indicate that CAPE-aspirin hybrid represents a valid and safe new chemical entity potentially useful for the treatment of ocular inflammation. PMID:25704612

  18. Effect of acid or alkaline catalyst and of different capping agents on the optical properties of CdS nanoparticles incorporated within a diureasil hybrid matrix

    NASA Astrophysics Data System (ADS)

    Gonçalves, Luis F. F. F.; Silva, Carlos J. R.; Kanodarwala, Fehmida K.; Stride, John A.; Pereira, Mario R.

    2015-11-01

    CdS nanoparticles (NPs) were synthesized using colloidal methods and incorporated within a diureasil hybrid matrix. The surface capping of the CdS NPs by 3-mercaptopropyltrimethoxysilane (MPTMS) and 3-aminopropyltrimethoxysilane (APTMS) organic ligands during the incorporation of the NPs within the hybrid matrix has been investigated. The matrix is based on poly(ethylene oxide)/poly(propylene oxide) chains grafted to a siliceous skeleton through urea bonds and was produced by sol-gel process. Both alkaline and acidic catalysis of the sol-gel reaction were used to evaluate the effect of each organic ligand on the optical properties of the CdS NPs. The hybrid materials were characterized by absorption, steady-state and time-resolved photoluminescence spectroscopy and High Resolution Transmission Electron Microscopy (HR-TEM). The preservation of the optical properties of the CdS NPs within the diureasil hybrids was dependent on the experimental conditions used. Both organic ligands (APTMS and MPTMS) demonstrated to be crucial in avoiding the increase of size distribution and clustering of the NPs within the hybrid matrix. The use of organic ligands was also shown to influence the level of interaction between the hybrid host and the CdS NPs. The CdS NPs showed large Stokes shifts and long average lifetimes, both in colloidal solution and in the xerogels, due to the origin of the PL emission in surface states. The CdS NPs capped with MPTMS have lower PL lifetimes compared to the other xerogel samples but still larger than the CdS NPs in the original colloidal solution. An increase in PL lifetimes of the NPs after their incorporation within the hybrid matrix is related to interaction between the NPs and the hybrid host matrix.

  19. Atomic layer deposition of organic-inorganic hybrid materials based on saturated linear carboxylic acids.

    PubMed

    Klepper, Karina Barnholt; Nilsen, Ola; Hansen, Per-Anders; Fjellvåg, Helmer

    2011-05-01

    Atomic layer deposition (ALD) has successfully provided thin films of organic-inorganic hybrid materials based on saturated linear carboxylic acids and trimethylaluminium (TMA). Films were grown for seven carboxylic acids: oxalic, malonic, succinic, glutaric, pimelic, suberic and sebacic acid, i.e. ranging from 2 to 10 carbon atoms in the molecular structure. These processes show exceptionally high growth rates; up to 4.3 nm/cycle for the pimelic acid-TMA system. Quartz crystal microbalance measurements of the growth dynamics indicate that all systems are of a self limiting ALD-type. Nevertheless, temperature dependent growth was observed in several systems. The width of the ALD windows shows correlations with the length of the carbon chains. Fourier transform infrared spectroscopy clearly proved that the deposited films are of a hybrid character, where the carboxylic acids primarily form bidentate complexes, though bridging complexes may also form. All films are X-ray amorphous as deposited. The films were further analyzed by atomic force microscopy for surface roughness and topography, UV-Vis spectroscopy and ellipsometry for optical properties, and the goniometer method for measuring sessile drops for surface wetting properties. Apart from the oxalic and malonic acid-TMA systems, the films are stable in contact with water. The films are generally smooth, transparent and have a refractive index close to 1.5. The complete coverage and accurate growth control offered by the ALD technique is here proven to provide surface-functionalized hybrid materials resembling metal-organic frameworks (MOF), probably as rather dense structures, yet with substantial potential for applications. PMID:21442116

  20. Reactions of chloride complexes of ruthenium (IV) with formic acid and sodium formate in aqueous solutions

    SciTech Connect

    Simanova, S.A.; Krylova, G.S.; Maslov, E.I.

    1982-04-20

    Study of the reactions of (NH/sub 4/)/sub 2/RuCl/sub 6/ with formic acid and sodium formate showed that, depending on the conditions, chlorocarbonyl, chloroformatocarbonyl, or chloroformato complexes of ruthenium(III) are formed.

  1. A Mini-Review on Solid Acid Catalysts for Esterification Reactions

    NASA Astrophysics Data System (ADS)

    Sirsam, Rajkumar; Hansora, Dharmesh; Usmani, Ghayas A.

    2016-04-01

    This paper presents an overview of research pertaining to solid acid catalysts for esterification reactions. Prominence has been given to the literatures that have been appeared during the last two decades. A variety of reactions catalyzed by solid acid catalysts have been tabulated according to their broad classification; industrially important reactions have been outlined. Examples, where the use of various solid acid catalysts have led to an improvement in the selectivity of the desired products, have also been discussed. Various catalyzed esterification reactions using different approaches and previous kinetic studies have been reviewed. Types, preparation and synthesis of various solid acid catalysts have been reviewed and discussed. Suggestions have been summarized for their implementation in future work.

  2. Citric Acid-Modified Fenton's Reaction for the Oxidation of Chlorinated Ethylenes in Soil Solution Systems

    SciTech Connect

    Seol, Yongkoo; Javandel, Iraj

    2008-03-15

    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 H{sub 2}O{sub 2} 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 H{sub 2}O{sub 2} relative to iron catalysts (Fe{sup 2+}/H{sub 2}O{sub 2} < 1/330) would result in lowering the efficiency of contaminant removal by iron chelations in the citric acid system. Column tests confirmed that citric acid could provide suitable acidic conditions to achieve higher than 55% contaminant removal rates.

  3. Reaction of /alpha/,/beta/-unsaturated acyl isothiocyanates with salts of dithiocarbamic acids

    SciTech Connect

    Krus, K.; Masias, A.; Beletskaya, I.P.

    1989-01-10

    The reaction of unsaturated isothiocyanates with the sodium and calcium salts of N-alkyl- and N,N-dialkyldithiocarbamic acids was studied. Depending on the structure of the dithiocarbamate, the reaction products are thiazines or acyl dithiocarbamates. For the salts of methyldithiocarbamic acid the effect of the concentration and the nature of the metal on the relative yields of 6-phenyl-3-methylpropiorhodanine and 6-phenylpropiorhodanine was studied. A method is proposed for the synthesis of 3-substituted propiorhodanines.

  4. Koch–Haaf reaction of adamantanols in an acid-tolerant hastelloy-made microreactor

    PubMed Central

    Mukai, Yu

    2011-01-01

    Summary The Koch–Haaf reaction of adamantanols was successfully carried out in a microflow system at room temperature. By combining an acid-tolerant hastelloy-made micromixer, a PTFE tube, and a hastelloy-made microextraction unit, a packaged reaction-to-workup system was developed. By means of the present system, the multigram scale synthesis of 1-adamantanecarboxylic acid was achieved in ca. one hour operation. PMID:21977213

  5. Mismatch discrimination in fluorescent in situ hybridization using different types of nucleic acids.

    PubMed

    Fontenete, Silvia; Silvia, Fontenete; Barros, Joana; Joana, Barros; Madureira, Pedro; Pedro, Madureira; Figueiredo, Céu; Céu, Figueiredo; Wengel, Jesper; Jesper, Wengel; Azevedo, Nuno Filipe; Filipe, Azevedo Nuno

    2015-05-01

    In the past few years, several researchers have focused their attention on nucleic acid mimics due to the increasing necessity of developing a more robust recognition of DNA or RNA sequences. Fluorescence in situ hybridization (FISH) is an example of a method where the use of these novel nucleic acid monomers might be crucial to the success of the analysis. To achieve the expected accuracy in detection, FISH probes should have high binding affinity towards their complementary strands and discriminate effectively the noncomplementary strands. In this study, we investigate the effect of different chemical modifications in fluorescent probes on their ability to successfully detect the complementary target and discriminate the mismatched base pairs by FISH. To our knowledge, this paper presents the first study where this analysis is performed with different types of FISH probes directly in biological targets, Helicobacter pylori and Helicobacter acinonychis. This is also the first study where unlocked nucleic acids (UNA) were used as chemistry modification in oligonucleotides for FISH methodologies. The effectiveness in detecting the specific target and in mismatch discrimination appears to be improved using locked nucleic acids (LNA)/2'-O-methyl RNA (2'OMe) or peptide nucleic acid (PNA) in comparison to LNA/DNA, LNA/UNA, or DNA probes. Further, the use of LNA modifications together with 2'OMe monomers allowed the use of shorter fluorescent probes and increased the range of hybridization temperatures at which FISH would work. PMID:25840566

  6. Approaches to the detection of enteric pathogens, including Campylobacter, using nucleic acid hybridization.

    PubMed

    Tompkins, L S; Krajden, M

    1986-03-01

    A previous study of the detection of Campylobacter jejuni in fecal samples spotted directly onto nitrocellulose filters before hybridization revealed a relatively low sensitivity and some false-positive results. We have investigated two factors that interfere with the detection of Campylobacter jejuni in fecal samples: interfering substances that create false-positive background signals and nonspecificity of the probe. Heterologous deoxyribonucleic acid probes bound nonspecifically to partially extracted fecal samples, indicating that the major basis for false-positive background was not due to homologous sequences. The problem of false-positive results could be reduced, but not eliminated, by extensive deoxyribonucleic acid extraction procedures applied to the clinical sample. The relative concentration of protein in each sample may be an important contributor to nonspecific binding. Other measures, such as sonication, glass bead fragmentation, and column separation, were not helpful. Development of a species-specific deoxyribonucleic acid probe derived from sequences encoding 16S ribonucleic acid is underway. PMID:3698541

  7. An exonuclease-assisted amplification electrochemical aptasensor for Hg(2+) detection based on hybridization chain reaction.

    PubMed

    Bao, Ting; Wen, Wei; Zhang, Xiuhua; Xia, Qinghua; Wang, Shengfu

    2015-08-15

    In this work, a novel electrochemical aptasensor was developed for Hg(2+) detection based on exonuclease-assisted target recycling and hybridization chain reaction (HCR) dual signal amplification strategy. The presence of Hg(2+) induced the T-rich DNA partly folded into duplex-like structure via the Hg(2+) mediated T-Hg(2+)-T base pairs, which triggered the activity of exonuclease III (Exo III). Exo III selectively digested the double-strand DNA containing multiple T-Hg(2+)-T base pairs from its 3'-end, the released Hg(2+) participated analyte recycle. With each digestion cycle, a digestion product named as help DNA was obtained, which acted as a linkage between the capture DNA and auxiliary DNA. The presence of help DNA and two auxiliary DNA collectively facilitated successful HCR process and formed long double-stranded DNA. [Ru(NH3)6](3+) was used as redox indicator, which electrostatically bound to the double strands and produced an electrochemical signal. Exo III-assisted target recycling and HCR dual amplification significantly improved the sensitivity for Hg(2+) with a detection limit of 0.12 pM (S/N=3). Furthermore, the proposed aptasensor had a promising potential for the application of Hg(2+) detection in real aquatic sample analysis. PMID:25840017

  8. 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 μg 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

  9. Label-free colorimetric aptasensor for sensitive detection of ochratoxin A utilizing hybridization chain reaction.

    PubMed

    Wang, Chengke; Dong, Xiaoya; Liu, Qian; Wang, Kun

    2015-02-20

    The combination of high selectivity of aptamer with the peroxidase-mimicking property of DNAzyme has presented considerable opportunities for designing colorimetric aptasensor for detection of ochratoxin A (OTA). The activities of both aptamer (as biorecognition element) and DNAzyme (as signal amplification element) are blocked via base pairing in the hairpin structure. Hybridization chain reaction (HCR) between two hairpin DNAs was employed to further improve the sensitivity of this method. The presence of OTA triggers the opening of the hairpin structure and the beginning of HCR, which results in the release of many DNAzyme, and generates enhanced colorimetric signals, which is correlated to the amounts of OTA with linear range between 0.01 to 0.32 nM, and the limit of detection is 0.01 nM under optimal conditions. OTA in yellow rice wine and wheat flour samples was also detected using this method. We demonstrate that a new colorimetric method for the detection of OTA has been established, which is simple, easy to conduct, label-free, sensitive, high throughput, and cost-saving. PMID:25682251

  10. 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

  11. Hybridization chain reaction amplification for highly sensitive fluorescence detection of DNA with dextran coated microarrays.

    PubMed

    Chao, Jie; Li, Zhenhua; Li, Jing; Peng, Hongzhen; Su, Shao; Li, Qian; Zhu, Changfeng; Zuo, Xiaolei; Song, Shiping; Wang, Lianhui; Wang, Lihua

    2016-07-15

    Microarrays of biomolecules hold great promise in the fields of genomics, proteomics, and clinical assays on account of their remarkably parallel and high-throughput assay capability. However, the fluorescence detection used in most conventional DNA microarrays is still limited by sensitivity. In this study, we have demonstrated a novel universal and highly sensitive platform for fluorescent detection of sequence specific DNA at the femtomolar level by combining dextran-coated microarrays with hybridization chain reaction (HCR) signal amplification. Three-dimensional dextran matrix was covalently coated on glass surface as the scaffold to immobilize DNA recognition probes to increase the surface binding capacity and accessibility. DNA nanowire tentacles were formed on the matrix surface for efficient signal amplification by capturing multiple fluorescent molecules in a highly ordered way. By quantifying microscopic fluorescent signals, the synergetic effects of dextran and HCR greatly improved sensitivity of DNA microarrays, with a detection limit of 10fM (1×10(5) molecules). This detection assay could recognize one-base mismatch with fluorescence signals dropped down to ~20%. This cost-effective microarray platform also worked well with samples in serum and thus shows great potential for clinical diagnosis. PMID:26922047

  12. Trace MicroRNA Quantification by Means of Plasmon-Enhanced Hybridization Chain Reaction.

    PubMed

    Yin, Fangfei; Liu, Huiqiao; Li, Qiang; Gao, Xia; Yin, Yongmei; Liu, Dingbin

    2016-05-01

    Quantifying trace microRNAs (miRNAs) is extremely important in a number of biomedical applications but remains a great challenge. Here we present an enzyme-free amplification strategy called plasmon-enhanced hybridization chain reaction (PE-HCR) for quantifying trace miRNAs with an outstanding linear range from 1 fM to 1 pM (r(2) = 0.991), along with a detection limit of 0.043 fM (1300 molecules in 50 μL of sample). The merits of the PE-HCR assay, including high sensitivity and specificity, quantitative detection, no enzyme involvement, low false positives, and easy-to-operate procedures, have been demonstrated for high-confidence quantification of the contents of miRNAs in even single cancer cells. The PE-HCR assay may open up new avenues for highly sensitive quantification of biomarkers and thus should hold great potentials in clinical diagnosis and prognosis. PMID:27088492

  13. Luminescent molecular hybrid system derived from 2-furancarboxylic acid and silylated monomer coordinated to rare earth ions

    NASA Astrophysics Data System (ADS)

    Sui, Yu-Long; Yan, Bing

    2006-04-01

    In this study, silica-based organic-inorganic hybrids were prepared by the sol-gel method. Tetraethoxysilane (abbreviated as TEOS) and a kind of monomer (abbreviated as FA-APES) derived from modified 2-furancarboxylic acid (abbreviated as FA) with (3-aminopropyl)triethoxysilane (abbreviated as APES) were used as the inorganic and organic fragments, respectively. Coordination reaction between lanthanides (europium and terbium ions) and sbnd C dbnd O group of the monomer happened simultaneously. And after days of aging process the resultant materials showed characteristic luminescence of lanthanides. The enhancement of luminescence can be seen by the comparison with simply doped lanthanide hybrid systems. And it can be explained by the coordination ability of the organic counterpart. IR, NMR, UV-vis absorption, low-temperature phosphorescence spectroscopy and fluorescence spectroscopy were applied to characterize and the above spectroscopic data revealed that the triplet state energy of organic ligand matches with the emissive energy level of lanthanides (especially of Tb 3+).

  14. 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

  15. 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…

  16. Kinetics of the reaction of hypobromous acid and organic matters in water treatment processes.

    PubMed

    Echigo, S; Minear, R A

    2006-01-01

    The fate of bromine species from human activity is affected by the bromination reaction in water treatment processes. In this study, kinetic information of the reaction between hypobromous acid (HOBr) and seven different natural organic matters (NOM) was collected by sequential stopped-flow techniques. Multiple reaction phases were found in the reaction between HOBr and NOM. The number of reaction sites for the faster reaction phase ranged from 0.26 to 0.92 micromole (mg DOC)(-1), and was correlated to both SUVA and specific phenolic content at pH 7.0. The apparent second-order rate constants for the faster reaction phase at pH 7.0 ranged from 5.4 x 10(5) to 1.4 x 10(6) M(-1) x s(-1), indicating that vanillin-like structures are involved in this reaction phase. PMID:16862795

  17. Sulfonic acid-functionalized hybrid organic-inorganic proton exchange membranes synthesized by sol-gel using 3-mercaptopropyl trimethoxysilane (MPTMS)

    NASA Astrophysics Data System (ADS)

    Mosa, J.; Durán, A.; Aparicio, M.

    2015-11-01

    Organic/inorganic hybrid membranes based on (3-glycidoxypropyl) trimethoxysilane (GPTMS) and 3-mercaptopropyl trimethoxysilane (MPTMS) have been prepared by sol-gel method and organic polymerisation, as candidate materials for proton exchange membranes in direct alcohol fuel cell (DMFC) applications. The -SH groups of MPTMS are oxidized to sulfonic acid groups, which are attributed to enhance the proton conductivity of hybrid membranes. FTIR, XPS and contact angle were used to characterize and confirm the hybrid structure and oxidation reaction progress. Membranes characterization also includes ion exchange capacity, water uptake, methanol permeability and proton conductivity to confirm their applicability in fuel cells. All the membranes were homogeneous and thermally and chemically resistant. In particular, the hybrid membranes demonstrated proton conductivities as high as 0.16 S cm-1 at high temperature, while exhibiting a low methanol permeability as compared to Nafion®. These results are associated with proton conducting paths through the silica pseudo-PEO network in which sulfonic acid groups work as proton donor.

  18. 40 CFR 721.10448 - Acetic acid, hydroxy- methoxy-, methyl ester, reaction products with substituted alkylamine...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... ester, reaction products with substituted alkylamine (generic). 721.10448 Section 721.10448 Protection... NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10448 Acetic acid, hydroxy- methoxy-, methyl ester, reaction products with substituted alkylamine (generic)....

  19. 40 CFR 721.10448 - Acetic acid, hydroxy- methoxy-, methylester, reaction products with substituted alkylamine...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-, methylester, reaction products with substituted alkylamine (generic). 721.10448 Section 721.10448 Protection... NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10448 Acetic acid, hydroxy- methoxy-, methylester, reaction products with substituted alkylamine (generic)....

  20. Acid-Base Chemistry According to Robert Boyle: Chemical Reactions in Words as well as Symbols

    ERIC Educational Resources Information Center

    Goodney, David E.

    2006-01-01

    Examples of acid-base reactions from Robert Boyle's "The Sceptical Chemist" are used to illustrate the rich information content of chemical equations. Boyle required lengthy passages of florid language to describe the same reaction that can be done quite simply with a chemical equation. Reading or hearing the words, however, enriches the student's…

  1. CHROMATOGRAPHIC SEPARATION AND IDENTIFICATION OF PRODUCTS FROM THE REACTION OF DIMETHYLARSINIC ACID WITH HYDROGEN SULFIDE

    EPA Science Inventory

    The reaction of dimethylarsinic acid (DMAV) with hydrogen sulfide (H2S) is of biological significance and may be implicated in the overall toxicity and carcinogenicity of arsenic. The course of the reaction in aqueous phase was monitored and an initial product, dimethylthioarsin...

  2. Adsorption of porphyrin and carminic acid on TiO2 nanoparticles: A photo-active nano-hybrid material for hybrid bulk heterojunction solar cells.

    PubMed

    Munir, Shamsa; Shah, Syed Mujtaba; Hussain, Hazrat; Siddiq, Muhammad

    2015-12-01

    A photo-active nano-hybrid material consisting of titania nanoparticles, carminic acid, and sulphonic acid functionalized porphyrin is reported here. In an attempt to extend the absorption spectrum of titania to visible region by co-adsorbing carminic acid and sulphonic acid functionalized porphyrin on its surface. Interesting changes in the UV-visible and fluorescence spectra were noticed. The adsorption of carminic acid resulted in the formation of charge transfer complex with titania nanoparticles. This was confirmed by the electronic absorption and fluorescence emission spectroscopies. Chemisorption of porphyrin on the carminic acid functionalized titania further boosted the charge transfer effect. This was noticed by the increase in intensity and width of the charge transfer absorption and emission bands. Energy level diagram showed that the interaction among the constituents of the nano-hybrid assembly permitted the flow of electron in a cascade manner from carminic acid to TiO2.This also allowed direct flow of electrons either from carminic acid or porphyrin toward titania. The material was used as an active blend in hybrid bulk heterojunction solar cells. Co-functionalized TiO2-based devices were found 3.5 times more efficient than the reference device but morphology of the device proved a major setback. PMID:26555643

  3. Asymmetric synthesis of beta-hydroxy amino acids via aldol reactions catalyzed by chiral ammonium salts.

    PubMed

    Mettath, Sashikumar; Srikanth, G S C; Dangerfield, Benjamin S; Castle, Steven L

    2004-09-17

    The Cinchona alkaloid derived chiral ammonium salt developed by Park and Jew functions as an effective catalyst for the synthesis of beta-hydroxy alpha-amino acids via asymmetric aldol reactions under homogeneous conditions. The syn diastereomers are obtained in good ee, and aryl-substituted aliphatic aldehydes are the best substrates for the reaction. These results represent the highest ee's obtained to date in direct aldol reactions of glycine equivalents catalyzed by inexpensive, readily prepared chiral ammonium salts. PMID:15357616

  4. 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.

  5. Naturally occurring hybrids derived from γ-amino acids and sugars with potential tail to tail ether-bonds

    PubMed Central

    Feng, Zi-ming; Zhan, Zhi-lai; Yang, Ya-nan; Jiang, Jian-shuang; Zhang, Pei-cheng

    2016-01-01

    The basic substances of life include various amino acids and sugars. To search such molecules is the precondition to understand the essential nature. Here we reported four unprecedented hybrids of γ-amino acids and sugars from the roots of Ranunculus ternatus, which possess potential tail to tail ether-connected (6,6-ether-connected) modes in the sugar moiety. The structures of these hybrids were elucidated by extensive analyses of spectra and calculated electronic circular dichroism (ECD) method. PMID:27166276

  6. Naturally occurring hybrids derived from γ-amino acids and sugars with potential tail to tail ether-bonds.

    PubMed

    Feng, Zi-Ming; Zhan, Zhi-Lai; Yang, Ya-Nan; Jiang, Jian-Shuang; Zhang, Pei-Cheng

    2016-01-01

    The basic substances of life include various amino acids and sugars. To search such molecules is the precondition to understand the essential nature. Here we reported four unprecedented hybrids of γ-amino acids and sugars from the roots of Ranunculus ternatus, which possess potential tail to tail ether-connected (6,6-ether-connected) modes in the sugar moiety. The structures of these hybrids were elucidated by extensive analyses of spectra and calculated electronic circular dichroism (ECD) method. PMID:27166276

  7. 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

    2015-07-01

    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

  8. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9484 Dimer acid/rosin amidoamine reaction product (generic). (a... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Dimer acid/rosin amidoamine...

  9. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9484 Dimer acid/rosin amidoamine reaction product (generic). (a... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Dimer acid/rosin amidoamine...

  10. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9484 Dimer acid/rosin amidoamine reaction product (generic). (a... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Dimer acid/rosin amidoamine...

  11. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9484 Dimer acid/rosin amidoamine reaction product (generic). (a... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Dimer acid/rosin amidoamine...

  12. 40 CFR 721.9484 - Dimer acid/rosin amidoamine reaction product (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9484 Dimer acid/rosin amidoamine reaction product (generic). (a... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Dimer acid/rosin amidoamine...

  13. 40 CFR 721.10126 - Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkyl amino substituted triazine amino substituted benezenesulfonic acid reaction product with naphthalenesulfonato azo substituted phenyl azo substituted benzenesulfonic acid copper compound (generic). 721.10126 Section 721.10126 Protection of Environment ENVIRONMENTAL PROTECTION...

  14. 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.…

  15. 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

  16. Au-ZnO hybrid nanoflowers, nanomultipods and nanopyramids: one-pot reaction synthesis and photocatalytic properties

    NASA Astrophysics Data System (ADS)

    Chen, Yuanzhi; Zeng, Deqian; Zhang, Kun; Lu, Aolin; Wang, Laisen; Peng, Dong-Liang

    2013-12-01

    The preparation of noble metal-semiconductor hybrid nanocrystals with controlled morphologies has received intensive interest in recent years. In this study, facile one-pot reactions have been developed for the synthesis of Au-ZnO hybrid nanocrystals with different interesting morphologies, including petal-like and urchin-like nanoflowers, nanomultipods and nanopyramids. In the synthesis strategy, oleylamine-containing solution serves as the reaction medium, and the in situ generated Au seeds play an important role in the subsequently induced growth of ZnO nanocrystals. With the aid of several surfactants, hybrid nanocrystals with different morphologies that have considerable influences on their optical and photocatalytic activities are readily achieved. Through high-resolution transmission electron microscopy measurements, an observed common orientation relationship between ZnO and Au is that ZnO nanocrystals prefer to grow with their polar {001} facets on the {111} facets of Au nanocrystals, and well-defined interfaces are evident. Surface plasmon resonance bands of Au with different positions are observed in the UV-vis spectra, and the UV and visible emissions of ZnO are found to be dramatically reduced. Finally, the as-prepared Au-ZnO nanocrystals exhibit excellent photocatalytic activity for the photodegradation of rhodamine B compared with pure ZnO nanocrystals. The Au-ZnO hybrid nanopyramids show the highest catalytic efficiency, which is correlated with the exposed crystal facets, crystallinity and the formation of hybrid nanostructures. The as-prepared Au-ZnO hybrid nanocrystals are expected to find diverse potential applications in the fields such as photocatalysis, solar energy conversion, sensing and biological detection.The preparation of noble metal-semiconductor hybrid nanocrystals with controlled morphologies has received intensive interest in recent years. In this study, facile one-pot reactions have been developed for the synthesis of Au-ZnO hybrid nanocrystals with different interesting morphologies, including petal-like and urchin-like nanoflowers, nanomultipods and nanopyramids. In the synthesis strategy, oleylamine-containing solution serves as the reaction medium, and the in situ generated Au seeds play an important role in the subsequently induced growth of ZnO nanocrystals. With the aid of several surfactants, hybrid nanocrystals with different morphologies that have considerable influences on their optical and photocatalytic activities are readily achieved. Through high-resolution transmission electron microscopy measurements, an observed common orientation relationship between ZnO and Au is that ZnO nanocrystals prefer to grow with their polar {001} facets on the {111} facets of Au nanocrystals, and well-defined interfaces are evident. Surface plasmon resonance bands of Au with different positions are observed in the UV-vis spectra, and the UV and visible emissions of ZnO are found to be dramatically reduced. Finally, the as-prepared Au-ZnO nanocrystals exhibit excellent photocatalytic activity for the photodegradation of rhodamine B compared with pure ZnO nanocrystals. The Au-ZnO hybrid nanopyramids show the highest catalytic efficiency, which is correlated with the exposed crystal facets, crystallinity and the formation of hybrid nanostructures. The as-prepared Au-ZnO hybrid nanocrystals are expected to find diverse potential applications in the fields such as photocatalysis, solar energy conversion, sensing and biological detection. Electronic supplementary information (ESI) available: EDS spectra, SEM images and TEM images of products synthesized under different conditions, and time-dependent UV-vis spectra recorded during the photocatalytic degradation of RhB by using different samples. See DOI: 10.1039/c3nr04558g

  17. Structural Origin of the Activity in Mn3O4-Graphene Oxide Hybrid Electrocatalysts for the Oxygen Reduction Reaction.

    PubMed

    Wu, Kuang-Hsu; Zeng, Qingcong; Zhang, Bingsen; Leng, Xue; Su, Dang-Sheng; Gentle, Ian R; Wang, Da-Wei

    2015-10-12

    Non-precious metal oxide/carbon hybrid electrocatalysts are of increasing importance for the oxygen reduction reaction (ORR). A synergistic effect is commonly used to explain the superior ORR activity exerted by metal oxide/nanocarbon hybrids, and this effect is attributed to covalently coupled interfaces between the two materials. However, the origin of the high activity, the structure, and the electrocatalytic nature of the interface remain unclear. By combining X-ray photoelectron spectroscopy with synchrotron far-infrared spectroscopy, we resolved the interface structure between spinel manganese oxide nanocrystals and graphene oxide nanoribbons, and the role of this interface in the promoted ORR. Moreover, we demonstrated the excellent ORR activity by a functional synergism of the hybrid constituents through a series of comparative electrochemical experiments. PMID:26448527

  18. 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

  19. The Use of Gel Electrophoresis to Study the Reactions of Activated Amino Acids with Oligonucleotides

    NASA Technical Reports Server (NTRS)

    Zieboll, Gerhard; Orgel, Leslie E.

    1994-01-01

    We have used gel electrophoresis to study the primary covalent addition of amino acids to oligonu-cleotides or their analogs and the subsequent addition of further molecules of the amino acids to generate peptides covalently linked to the oligonucleotides. We have surveyed the reactions of a variety of amino acids with the phosphoramidates derived from oligonucleotide 5 inches phosphates and ethylenediamine. We find that arginine and amino acids can interact with oligonucleotidesl through stacking interactions react most efficiently. D- and L-amino acids give indistinguishable families of products.

  20. Reaction kinetics of free fatty acids esterification in palm fatty acid distillate using coconut shell biochar sulfonated catalyst

    NASA Astrophysics Data System (ADS)

    Hidayat, Arif; Rochmadi, Wijaya, Karna; Budiman, Arief

    2015-12-01

    Recently, a new strategy of preparing novel carbon-based solid acids has been developed. In this research, the esterification reactions of Palm Fatty Acid Distillate (PFAD) with methanol, using coconut shell biochar sulfonated catalyst from biomass wastes as catalyst, were studied. In this study, the coconut shell biochar sulfonated catalysts were synthesized by sulfonating the coconut shell biochar using concentrated H2SO4. The kinetics of free fatty acid (FFA) esterification in PFAD using a coconut shell biochar sulfonated catalyst was also studied. The effects of the mass ratio of catalyst to oil (1-10%), the molar ratio of methanol to oil (6:1-12:1), and the reaction temperature (40-60°C) were studied for the conversion of PFAD to optimize the reaction conditions. The results showed that the optimal conditions were an methanol to PFAD molar ratio of 12:1, the amount of catalyst of 10%w, and reaction temperature of 60°C. The proposed kinetic model shows a reversible second order reaction and represents all the experimental data satisfactorily, providing deeper insight into the kinetics of the reaction.

  1. Engineering of a novel hybrid enzyme: an anti-inflammatory drug target with triple catalytic activities directly converting arachidonic acid into the inflammatory prostaglandin E2

    PubMed Central

    Ruan, Ke-He; Cervantes, Vanessa; So, Shui-Ping

    2009-01-01

    Cyclooxygenase isoform-2 (COX-2) and microsomal prostaglandin E2 synthase-1 (mPGES-1) are inducible enzymes that become up-regulated in inflammation and some cancers. It has been demonstrated that their coupling reaction of converting arachidonic acid (AA) into prostaglandin (PG) E2 (PGE2) is responsible for inflammation and cancers. Understanding their coupling reactions at the molecular and cellular levels is a key step toward uncovering the pathological processes in inflammation. In this paper, we describe a structure-based enzyme engineering which produced a novel hybrid enzyme that mimics the coupling reactions of the inducible COX-2 and mPGES-1 in the native ER membrane. Based on the hypothesized membrane topologies and structures, the C-terminus of COX-2 was linked to the N-terminus of mPGES-1 through a transmembrane linker to form a hybrid enzyme, COX-2-10aa-mPGES-1. The engineered hybrid enzyme expressed in HEK293 cells exhibited strong triple-catalytic functions in the continuous conversion of AA into PGG2 (catalytic-step 1), PGH2 (catalytic-step 2) and PGE2 (catalytic-step 3), a pro-inflammatory mediator. In addition, the hybrid enzyme was also able to directly convert dihomo-gamma-linolenic acid (DGLA) into PGG1, PGH1 and then PGE1 (an anti-inflammatory mediator). The hybrid enzyme retained similar Kd and Vmax values to that of the parent enzymes, suggesting that the configuration between COX-2 and mPGES-1 (through the transmembrane domain) could mimic the native conformation and membrane topologies of COX-2 and mPGES-1 in the cells. The results indicated that the quick coupling reaction between the native COX-2 and mPGES-1 (in converting AA into PGE2) occurred in a way so that both enzymes are localized near each other in a face-to-face orientation, where the COX-2 C-terminus faces the mPGES-1 N-terminus in the ER membrane. The COX-2-10aa-mPGES-1 hybrid enzyme engineering may be a novel approach in creating inflammation cell and animal models, which are particularly valuable targets for the next generation of NSAID screening. PMID:19850676

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

    PubMed

    Steger, G

    1994-07-25

    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. PMID:8052531

  3. FeOOH/Co/FeOOH Hybrid Nanotube Arrays as High-Performance Electrocatalysts for the Oxygen Evolution Reaction.

    PubMed

    Feng, Jin-Xian; Xu, Han; Dong, Yu-Tao; Ye, Sheng-Hua; Tong, Ye-Xiang; Li, Gao-Ren

    2016-03-01

    Herein, we developed FeOOH/Co/FeOOH hybrid nanotube arrays (HNTAs) supported on Ni foams for oxygen evolution reaction (OER). The inner Co metal cores serve as highly conductive layers to provide reliable electronic transmission, and can overcome the poor electrical conductivity of FeOOH efficiently. DFT calculations demonstrate the strong electronic interactions between Co and FeOOH in the FeOOH/Co/FeOOH HNTAs, and the hybrid structure can lower the energy barriers of intermediates and thus promote the catalytic reactions. The FeOOH/Co/FeOOH HNTAs exhibit high electrocatalytic performance for OER, such as low onset potential, small Tafel slope, and excellent long-term durability, and they are promising electrocatalysts for OER in alkaline solution. PMID:26879125

  4. Acidbase bifunctional shell cross-linked micelle nanoreactor for one-pot tandem reaction

    SciTech Connect

    Lee, Li -Chen; Lu, Jie; Weck, Marcus; Jones, Christopher W.

    2015-12-29

    Shell cross-linked micelles (SCMs) containing acid sites in the shell and base sites in the core are prepared from amphiphilic poly(2-oxazoline) triblock copolymers. The materials are utilized as two-chamber nanoreactors for a prototypical acid-base bifunctional tandem deacetalization-nitroaldol reaction. Furthermore, the acid and base sites are localized in different regions of the micelle, allowing the two steps in the reaction sequence to largely proceed in separate compartments, akin to the compartmentalization that occurs in biological systems.

  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. 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

  7. Phase-separated structures of mixed Langmuir-Blodgett films of fatty acid and hybrid carboxylic acid.

    PubMed

    Kimura, Hideto; Watanabe, Satoshi; Shibata, Hirobumi; Azumi, Reiko; Sakai, Hideki; Abe, Masahiko; Matsumoto, Mutsuyoshi

    2008-12-01

    Phase separation often occurs in mixed Langmuir-Blodgett (LB) films. Usually circular domains at the micrometer length scale form in the LB films. The size and shape of the domains are governed by a compromise between two competing interactions of line tension and dipole-dipole interaction. An attempt was made to control the line tension by varying systematically the hydrophobic moieties of the film-forming molecules. Phase-separated structures of two-component mixed LB films of fatty acid [C(k)H(2k+1)COOH (HkA)] and hybrid carboxylic acid [C(m)F(2m+1)C(n)H(2n)COOH (FmHnA)] were investigated. IR spectra of the mixed LB films of H17A and F8H10A revealed that the alkyl chains were in an all-trans conformation and that the molecular orientation remained unchanged when the two components were mixed. Nanowires formed in the mixed LB films of HkA and F8H10A. The width of the nanowires increased with an increase in k. Domain size and shape in the mixed LB films of H17A and FmHnA depended strongly on the values of m and n. Circular domains at the micrometer length scale formed in the region m + n < 16. In contrast, domains at the nanometer length scale formed in the region m + n > or = 16 except for F6H10A. These results were explained by using a lattice model that considers the effect of the hydrophobic moieties of fatty acid and hybrid carboxylic acid on the line tension. PMID:19006269

  8. Luminescent hybrid lanthanide sulfates and lanthanide sulfonate-carboxylates with 1,10-phenanthroline involving in-situ oxidation of 2-mercaptonbenzoic acid

    SciTech Connect

    Zhong, Jie-Cen; Wan, Fang; Sun, Yan-Qiong; Chen, Yi-Ping

    2015-01-15

    A series of lanthanide sulfates and lanthanide sulfonate-carboxylates, [Ln{sub 2}(phen){sub 2}(SO{sub 4}){sub 3}(H{sub 2}O){sub 2}]{sub n} (I:Ln=Nd(1a), Sm(1b), Eu(1c), phen=1,10-phenanthroline) and [Ln(phen)(2-SBA)(BZA)]{sub n} (II: Ln=Sm(2a), Eu(2b), Dy(2c), 2-SBA=2-sulfobenzoate, BZA=benzoate) have been hydrothermally synthesized from lanthanide oxide, 2-mercaptonbenzoic acid with phen as auxiliary ligand and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra, TG analyses and luminescence spectroscopy. Interestingly, SO{sub 4}{sup 2−} anions in I came from the in situ deep oxidation of thiol groups of 2-mercaptonbenzoic acid while 2-sulfobenzoate and benzoate ligands in II from the middle oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. Compounds I are organic–inorganic hybrid lanthanide sulfates, which have rare one-dimensional column-like structures. Complexes II are binuclear lanthanide sulfonate-carboxylates with 2-sulfobenzoate and benzoate as bridges and 1,10-phenanthroline as terminal. Photoluminescence studies reveal that complexes I and II exhibit strong lanthanide characteristic emission bands in the solid state at room temperature. - Graphical abstract: Lanthanide sulfates and lanthanide sulfonate-carboxylates have been hydrothermally synthesized. Interestingly, sulfate anions, 2-sulfobenzoate and benzoate ligands came from the in situ oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. - Highlights: • In situ oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. • The organic–inorganic hybrid lanthanide sulfates with one-dimensional column-like structure. • The dinuclear lanthanide sulfonate-carboxylates. • The emission spectra exhibit the characteristic transition of {sup 5}D{sub 0}→{sup 7}F{sub J} (J=0–4) of the Eu(III)

  9. Graphene/sulfur hybrid nanosheets from a space-confined "sauna" reaction for high-performance lithium-sulfur batteries.

    PubMed

    Fei, Linfeng; Li, Xiaogang; Bi, Wentuan; Zhuo, Zhiwen; Wei, Wenfei; Sun, Li; Lu, Wei; Wu, Xiaojun; Xie, Keyu; Wu, Changzheng; Chan, Helen L W; Wang, Yu

    2015-10-21

    A space-confined "sauna" reaction system is introduced for the simultaneous reduction and functionalization of graphene oxide to unique graphene-sulfur hybrid nanosheets, in which thin layers of amorphous sulfur are tightly anchored on the graphene sheet via strong chemical bonding. Upon being used as the cathode material in lithium-sulfur batteries, the as-synthesized composite shows an excellent electrochemical performance. PMID:26310671

  10. Application and comparison of silver intensification methods for the diaminobenzidine and diaminobenzidine-nickel endproduct of the peroxidation reaction in immunohistochemistry and in situ hybridization.

    PubMed

    Mullink, H; Vos, W; Jiwa, M; Horstman, A; van der Valk, P; Walboomers, J M; Meijer, C J

    1992-04-01

    Silver-intensification methods described in the literature for the diaminobenzidine (DAB) and diaminobenzidine-nickel (DAB/Ni) endproduct of the peroxidase reaction were compared in model systems after immunoperoxidase and in situ hybridization. First, these methods were compared in immunohistochemical model systems, using the demonstration of glial fibrillar acidic protein (GFAP) and prostate-specific antigen (PSA) in paraffin sections of human brain and prostate tissue, respectively. When DAB without Ni was used as substrate, tissue argyrophilia caused considerable background staining. Only when this tissue reactivity was quenched with, e.g., CuSO4 with H2O2 or thioglycolic acid, were the results acceptable. A considerable improvement in the signal-to-noise ratio could be obtained when nickel was included in the substrate mixture. The methods that proved to be best for demonstration of GFAP and PSA made use of acid developer solutions. Subsequently, these methods were compared with other sensitive immunostaining methods for demonstration of the gamma-delta T-cell receptor in frozen lymphoid tissue. In this model a considerable increase in the number of positive cells could be obtained using silver intensification. The different methods using DAB/Ni were also compared for use in DNA in situ hybridization (DISH). In this case two model systems were used: human papilloma virus type 11 (HPV-11) DNA in condyloma tissue (abundant target model) and Epstein-Barr virus (EBV) DNA in a mononucleosis lymph node (low target model). For demonstration of HPV-11, all methods gave more or less satisfactory results, which were best with the acid developer solutions. Moreover, for demonstration of EBV DNA, a signal could be obtained only with these developer solutions. Such a method also proved suitable in double immuno-hybrido stainings for the demonstration of EBV DNA in specific antigen-positive Reed-Sternberg cells in paraffin sections of Hodgkin lymph nodes. PMID:1532404

  11. Label-Free Potentiometry for Detecting DNA Hybridization Using Peptide Nucleic Acid and DNA Probes

    PubMed Central

    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

  12. 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

  13. Label-free and enzyme-free colorimetric detection of microRNA by catalyzed hairpin assembly coupled with hybridization chain reaction.

    PubMed

    Wu, Hao; Liu, Yaling; Wang, Hongyong; Wu, Jun; Zhu, Feifan; Zou, Pei

    2016-07-15

    In this study, a simple, label-free, and enzyme-free colorimetric biosensor has been developed for amplified detection of let-7a microRNA (miRNA) on the basis of dual signal amplification strategy. The sensing system mainly consists of four unlabeled hairpin probes termed H1, H2, H3, and H4. Upon sensing of the target miRNA, hairpin H1 is opened. Then hairpin H2 hybridizes with H1 forming H1-H2 duplex and frees the target miRNA that can be recycled to trigger another reaction cycle. In addition, the newly formed H1-H2 duplex hybridizes with hairpin H3, and this triggers the autonomous cross-opening of the two hairpins H3 and H4 through hybridization chain reaction. During this process, numerous split G-quadruplex structures are generated and further associate with cofactor hemin to form massive peroxidase-mimicking DNAzymes. The resulting DNAzymes catalyze the H2O2-mediated oxidation of colorless 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS(2-)) to the green-colored ABTS(•-), inducing a remarkably amplified colorimetric signal. This newly developed sensing system exhibits high sensitivity toward miRNA with a detection limit of 7.4fM and a large dynamic range of 6 orders of magnitude from 10fM to 10nM. Furthermore, it exhibits a good performance to discriminate single-base difference among the miRNA family members and holds a great potential for early diagnosis in gene-related diseases. PMID:26985582

  14. 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 β-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 β-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. β-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 β-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 150 min 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

  15. 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.

  16. Hybrid Compounds Strategy in the Synthesis of Oleanolic Acid Skeleton-NSAID Derivatives.

    PubMed

    Pawełczyk, Anna; Olender, Dorota; Sowa-Kasprzak, Katarzyna; Zaprutko, Lucjusz

    2016-01-01

    The current study focuses on the synthesis of several hybrid individuals combining a natural oleanolic acid skeleton and synthetic nonsteroidal anti-inflammatory drug moieties (NSAIDs). It studied structural modifications of the oleanolic acid structure by use of the direct reactivity of hydroxyl or hydroxyimino groups at position C-3 of the triterpenoid skeleton with the carboxylic function of anti-inflammatory drugs leading to new perspective compounds with high potential pharmacological activities. Novel ester- and iminoester-type derivatives of oleanolic unit with the different NSAIDs, such as ibuprofen, aspirin, naproxen, and ketoprofen, were obtained and characterized. Moreover, preliminary research of compounds obtaining structure stability under acidic conditions was examined and the PASS method of prediction of activity spectra for substances was used to estimate the potential biological activity of these compounds. PMID:27077841

  17. The reaction of sulfite anion radical (SO .-3) with polyunsaturated fatty acids

    NASA Astrophysics Data System (ADS)

    Erben-Russ, M.; Bors, W.; Winter, R.; Saran, M.

    Using the pulse radiolysis technique, SO .-3 was produced in aqueous solution by the reaction of SO 2-3 with either .OH or the (pseudo-) halide radicals N .3, Br .-3, and (SCN) .-2; for the latter reactions rate constants were measured. The reaction of SO .-3 with linoleic, linolenic, and arachidonic acids was monitored using the strong absorption of the pentadienyl radical, one possible primary reaction product. In micellar systems no detectable reaction took place, however, monomeric fatty acids were observed to react with SO .-3. Lower limits of the rate constants for SO .-3 attack derived from the data are 1 × 10 5, 8 × 10 5, and 1.3 × 10 6 (dm 3 mol -1 s -1) for linoleate, linolenate, and arachidonate, respectively.

  18. Amorphous Molybdenum Sulfide on Graphene-Carbon Nanotube Hybrids as Highly Active Hydrogen Evolution Reaction Catalysts.

    PubMed

    Pham, Kien-Cuong; Chang, Yung-Huang; McPhail, David S; Mattevi, Cecilia; Wee, Andrew T S; Chua, Daniel H C

    2016-03-01

    In this study, we report on the deposition of amorphous molybdenum sulfide (MoSx, with x ≈ 3) on a high specific surface area conductive support of Graphene-Carbon Nanotube hybrids (GCNT) as the Hydrogen Evolution Reaction (HER) catalysts. We found that the high surface area GCNT electrode could support the deposition of MoSx at much higher loadings compared with simple porous carbon paper or flat graphite paper. The morphological study showed that MoSx was successfully deposited on and was in good contact with the GCNT support. Other physical characterization techniques suggested the amorphous nature of the deposited MoSx. With a typical catalyst loading of 3 mg cm(-2), an overpotential of 141 mV was required to obtain a current density of 10 mA cm(-2). A Tafel slope of 41 mV decade(-1) was demonstrated. Both measures placed the MoSx-deposited GCNT electrode among the best performing molybdenum sulfide-based HER catalysts reported to date. The electrode showed a good stability with only a 25 mV increase in overpotential required for a current density of 10 mA cm(-2), after undergoing 500 potential sweeps with vigorous bubbling present. The current density obtained at -0.5 V vs SHE (Standard Hydrogen Electrode potential) decreased less than 10% after the stability test. The deposition of MoSx on high specific surface area conductive electrodes demonstrated to be an efficient method to maximize the catalytic performance toward HER. PMID:26864503

  19. Ultrasensitive Multiplexed Immunoassay for Tumor Biomarkers Based on DNA Hybridization Chain Reaction Amplifying Signal.

    PubMed

    Guo, Jinjin; Wang, Junchun; Zhao, Junqing; Guo, Zilin; Zhang, Yuzhong

    2016-03-23

    In this work, a novel electrochemical immunoassay protocol has been reported for simultaneous determination of multiple tumor biomarkers based on DNA hybridization chain reaction (HCR) for signal amplification. Alpha-fetoprotein (AFP) and prostate specific antigen (PSA) were selected as model biomarkers. The immunoassay protocol contained primary antibodies immobilized on gold nanoparticles (Au NPs), secondary antibodies conjugated with DNA concatemer from HCR of primer, auxiliary probe, and signal probe labeled with signal molecules (methyleneblue (MB) and ferrocene (Fc)). In the presence of target biomarkers, the sandwich immunocomplex was formed between the primary antibodies and secondary antibodies bioconjugates carrying numerous signal molecules. As a result, two well-resolved reduction peaks, one was at -0.35 V (corresponding to MB) and other was at 0.33 V (corresponding to Fc; both vs SCE), were obtained in differential pulse voltammetry, and peak currents changed were related to the level of biomarkers. Under optimal conditions, the electrochemical immunoassay exhibited a wide linear response range (0.5 pg mL(-1) to 50 ng mL(-1)) and low detection limits (PSA, 0.17 pg mL(-1); AFP, 0.25 pg mL(-1)) (at S/N = 3). In addition, the immunoassay was evaluated by analyzing simulate human serum sample, and the recoveries obtained were within 99.4-107.6% for PSA and 97.9-108.2% for AFP, indicating the immnuoassay could be applied to the simultaneous detection of AFP and PSA in human serum samples. PMID:26937717

  20. 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

  1. Heavy metal removal from acid mine drainage by calcined eggshell and microalgae hybrid system.

    PubMed

    Choi, Hee-Jeong; Lee, Seung-Mok

    2015-09-01

    This study investigates the use of calcined eggshells and microalgae for the removal of heavy metals from acid mine drainage (AMD) and the simultaneous enhancement of biomass productivity. The experiment was conducted over a period of 6 days in a hybrid system containing calcined eggshells and the microalgae Chlorella vulgaris. The results show that the biomass productivity increased to ~8.04 times its initial concentration of 0.367 g/L as measured by an optical panel photobioreactor (OPPBR) and had a light transmittance of 95 % at a depth of 305 mm. On the other hand, the simultaneous percent removal of Fe, Cu, Zn, Mn, As, and Cd from the AMD effluent was found to be 99.47 to 100 %. These results indicate that the hybrid system with calcined eggshells and microalgae was highly effective for heavy metal removal in the AMD. PMID:25940497

  2. 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

  3. Deoxyribonucleic acid-based hybrid thin films for potential application as high energy density capacitors

    NASA Astrophysics Data System (ADS)

    Joyce, Donna M.; Venkat, Narayanan; Ouchen, Fahima; Singh, Kristi M.; Smith, Steven R.; Grabowski, Christopher A.; Terry Murray, P.; Grote, James G.

    2014-03-01

    Deoxyribonucleic acid (DNA) based hybrid films incorporating sol-gel-derived ceramics have shown strong promise as insulating dielectrics for high voltage capacitor applications. Our studies of DNA-CTMA (cetyltrimethylammonium) complex/sol-gel ceramic hybrid thin film devices have demonstrated reproducibility and stability in temperature- and frequency-dependent dielectric properties with dielectric constant k ˜ 5.0 (1 kHz), as well as reliability in DC voltage breakdown measurements, attaining values consistently in the range of 300-350 V/μm. The electrical/dielectric characteristics of DNA-CTMA films with sol-gel-derived ceramics were examined to determine the critical energy storage parameters such as voltage breakdown and dielectric constant.

  4. Acid-Catalyzed Reaction of Epoxides on Atmospheric Nanoparticles

    NASA Astrophysics Data System (ADS)

    Xu, W.; Gomez-Hernandez, M.; Lal, V.; Qiu, C.; Khalizov, A. F.; Wang, L.; Zhang, R.

    2013-12-01

    Aerosol plays an important role in affecting the earth climate and harming human health. Atmospheric aerosols can be formed from either primary emissions or gas-to-particle conversion process. Numerous studies, including both experimental and theoretical, have been carried out to elucidate the mechanism of gas-to-particle conversion process (a.k.a. nucleation) and the later growth stage of newly formed nanoparticles. However, a complete list of species involving in the nucleation and growth processes of nanoparticles is still poorly understood. The growth of newly formed sulfuric acid - water nanoparticles has been suggested to involve several potential organic vapors, such as amines, glyoxal, 2-4 hexadienal, and epoxides. In the present study, new formed sulfuric acid -water nanoparticles were size selected by a differential mobility analyzer and exposed to epoxide vapors. The size-change after exposure was detected using the second differential mobility analyzer. The size-enlarged particles were then collected by an electrostatic precipitator, thermal vaporized, and analyzed by an ion drift chemical ionization mass spectrometer. Our results show that the sizes of nanoparticles are increased considerably and the magnitude of the increment in size is size-dependent. Mass spectrometry analysis of the nanoparticles after exposure demonstrates that low volatile organosulfate and oligomers are formed in nanoparticles upon their exposure to epoxide vapors.

  5. Influences of acidic reaction and hydrolytic conditions on monosaccharide composition analysis of acidic, neutral and basic polysaccharides.

    PubMed

    Wang, Qing-Chi; Zhao, Xia; Pu, Jiang-Hua; Luan, Xiao-Hong

    2016-06-01

    Monosaccharide composition analysis is important for structural characterization of polysaccharides. To investigate the influences of acidic reaction and hydrolytic conditions on monosaccharide composition analysis of polysaccharides, we chose alginate, starch, chitosan and chondroitin sulfate as representative of acidic, neutral, basic and complex polysaccharides to compare the release degree of monosaccharides under different hydrolytic conditions. The hydrolysis stability of 10 monosaccharide standards was also explored. Results showed that the basic sugars were hard to release but stable, the acidic sugars (uronic acids) were easy to release but unstable, and the release and stability of neutral sugars were in between acidic and basic sugars. In addition, the hydrolysis process was applied to monosaccharide composition analysis of Hippocampus trimaculatus polysaccharide and the appropriate hydrolytic condition was accorded with that of the above four polysaccharides. Thus, different hydrolytic conditions should be used for the monosaccharide composition analysis of polysaccharides based on their structural characteristics. PMID:27083372

  6. Reaction of sorghum hybrids to anthracnose, grain mold and grain weathering in Burleson County, Texas, 2007

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thirty commercial hybrids were evaluated for resistance against anthracnose, caused by Colletotrichum sublineolum and grain mold or grain weathering caused by a number of fungal species at the Texas A&M University Agricultural Experiment Station in College Station (Burleson County). Six hybrids wer...

  7. Interactive effects of cadmium and acid rain on photosynthetic light reaction in soybean seedlings.

    PubMed

    Sun, Zhaoguo; Wang, Lihong; Chen, Minmin; Wang, Lei; Liang, Chanjuan; Zhou, Qing; Huang, Xiaohua

    2012-05-01

    Interactive effects of cadmium (Cd(2+)) and acid rain on photosynthetic light reaction in soybean seedlings were investigated under hydroponic conditions. Single treatment with Cd(2+) or acid rain and the combined treatment decreased the content of chlorophyll, Hill reaction rate, the activity of Mg(2+)-ATPase, maximal photochemical efficiency and maximal quantum yield, increased initial fluorescence and damaged the chloroplast structure in soybean seedlings. In the combined treatment, the change in the photosynthetic parameters and the damage of chloroplast structure were stronger than those of any single pollution. Meanwhile, Cd(2+) and acid rain had the interactive effects on the test indices in soybean seedlings. The results indicated that the combined pollution of Cd(2+) and acid rain aggravated the toxic effect of the single pollution of Cd(2+) or acid rain on the photosynthetic parameters due to the serious damage to the chloroplast structure. PMID:22182775

  8. Activation of stratospheric chlorine by reactions in liquid sulphuric acid

    SciTech Connect

    Cox, R.A.; MacKenzie, A.R. ); Mueller, R.H.; Peter, Th.; Crutzen, P.J. )

    1994-06-22

    The authors discuss activation mechanisms for chlorine compounds in the stratosphere, based on laboratory measurements for the solubility and reaction rates of HOCl and HCl in H[sub 2]SO[sub 4] solutions, as found on aerosols in the stratosphere. Their interest is in the impact of the large increase in aerosol loading in the stratosphere in the winter on 1991-92 due to the Mt. Pinatubo eruption. While laboratory data is not available for the temperature range close to 190 K, they argue that should the solubility and hydrolysis rates be high enough, this excess aerosol density could have contributed a significant additional amount of reactive chlorine to the stratosphere.

  9. Time-Resolved Nucleic Acid Hybridization Beacons Utilizing Unimolecular and Toehold-Mediated Strand Displacement Designs.

    PubMed

    Massey, Melissa; Ancona, Mario G; Medintz, Igor L; Algar, W Russ

    2015-12-01

    Nucleic acid hybridization probes are sought after for numerous assay and imaging applications. These probes are often limited by the properties of fluorescent dyes, prompting the development of new probes where dyes are paired with novel or nontraditional luminescent materials. Luminescent terbium complexes are an example of such a material, and these complexes offer several unique spectroscopic advantages. Here, we demonstrate two nonstem-loop designs for light-up nucleic acid hybridization beacons that utilize time-resolved Förster resonance energy transfer (TR-FRET) between a luminescent Lumi4-Tb cryptate (Tb) donor and a fluorescent reporter dye, where time-resolved emission from the dye provides an analytical signal. Both designs are based on probe oligonucleotides that are labeled at their opposite termini with Tb and a fluorescent reporter dye. In one design, a probe is partially blocked with a quencher dye-labeled oligonucleotide, and target hybridization is signaled through toehold-mediated strand displacement and loss of a competitive FRET pathway. In the other design, the intrinsic folding properties of an unblocked probe are utilized in combination with a temporal mechanism for signaling target hybridization. This temporal mechanism is based on a recently elucidated "sweet spot" for TR-FRET measurements and exploits distance control over FRET efficiencies to shift the Tb lifetime within or outside the time-gated detection window for measurements. Both the blocked and unblocked beacons offer nanomolar (femtomole) detection limits, response times on the order of minutes, multiplexing through the use of different reporter dyes, and detection in complex matrices such as serum and blood. The blocked beacons offer better mismatch selectivity, whereas the unblocked beacons are simpler in design. The temporal mechanism of signaling utilized with the unblocked beacons also plays a significant role with the blocked beacons and represents a new and effective strategy for developing FRET probes for bioassays. PMID:26562366

  10. 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.

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

    DOEpatents

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

    1998-03-24

    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. 14 figs.

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

    DOEpatents

    Lucas, Joe N.; Straume, Tore; Bogen, Kenneth T.

    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.

  13. 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

  14. 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

  15. 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.

  16. Mechanistic study of secondary organic aerosol components formed from nucleophilic addition reactions of methacrylic acid epoxide

    NASA Astrophysics Data System (ADS)

    Birdsall, A. W.; Miner, C. R.; Mael, L. E.; Elrod, M. J.

    2014-08-01

    Recently, methacrylic acid epoxide (MAE) has been proposed as a precursor to an important class of isoprene-derived compounds found in secondary organic aerosol (SOA): 2-methylglyceric acid (2-MG) and a set of oligomers, nitric acid esters and sulfuric acid esters related to 2-MG. However, the specific chemical mechanisms by which MAE could form these compounds have not been previously studied. In order to determine the relevance of these processes to atmospheric aerosol, MAE and 2-MG have been synthesized and a series of bulk solution-phase experiments aimed at studying the reactivity of MAE using nuclear magnetic resonance (NMR) spectroscopy have been performed. The present results indicate that the acid-catalyzed MAE reaction is more than 600 times slower than a similar reaction of an important isoprene-derived epoxide, but is still expected to be kinetically feasible in the atmosphere on more acidic SOA. The specific mechanism by which MAE leads to oligomers was identified, and the reactions of MAE with a number of atmospherically relevant nucleophiles were also investigated. Because the nucleophilic strengths of water, sulfate, alcohols (including 2-MG), and acids (including MAE and 2-MG) in their reactions with MAE were found to be of a similar magnitude, it is expected that a diverse variety of MAE + nucleophile product species may be formed on ambient SOA. Thus, the results indicate that epoxide chain reaction oligomerization will be limited by the presence of high concentrations of non-epoxide nucleophiles (such as water); this finding is consistent with previous environmental chamber investigations of the relative humidity-dependence of 2-MG-derived oligomerization processes and suggests that extensive oligomerization may not be likely on ambient SOA because of other competitive MAE reaction mechanisms.

  17. Mechanistic study of secondary organic aerosol components formed from nucleophilic addition reactions of methacrylic acid epoxide

    NASA Astrophysics Data System (ADS)

    Birdsall, A. W.; Miner, C. R.; Mael, L. E.; Elrod, M. J.

    2014-12-01

    Recently, methacrylic acid epoxide (MAE) has been proposed as a precursor to an important class of isoprene-derived compounds found in secondary organic aerosol (SOA): 2-methylglyceric acid (2-MG) and a set of oligomers, nitric acid esters, and sulfuric acid esters related to 2-MG. However, the specific chemical mechanisms by which MAE could form these compounds have not been previously studied with experimental methods. In order to determine the relevance of these processes to atmospheric aerosol, MAE and 2-MG have been synthesized and a series of bulk solution-phase experiments aimed at studying the reactivity of MAE using nuclear magnetic resonance (NMR) spectroscopy have been performed. The present results indicate that the acid-catalyzed MAE reaction is more than 600 times slower than a similar reaction of an important isoprene-derived epoxide, but is still expected to be kinetically feasible in the atmosphere on more acidic SOA. The specific mechanism by which MAE leads to oligomers was identified, and the reactions of MAE with a number of atmospherically relevant nucleophiles were also investigated. Because the nucleophilic strengths of water, sulfate, alcohols (including 2-MG), and acids (including MAE and 2-MG) in their reactions with MAE were found to be of similar magnitudes, it is expected that a diverse variety of MAE + nucleophile product species may be formed on ambient SOA. Thus, the results indicate that epoxide chain reaction oligomerization will be limited by the presence of high concentrations of non-epoxide nucleophiles (such as water); this finding is consistent with previous environmental chamber investigations of the relative humidity dependence of 2-MG-derived oligomerization processes and suggests that extensive oligomerization may not be likely on ambient SOA because of other competitive MAE reaction mechanisms.

  18. Ligand-Promoted, Boron-Mediated Chemoselective Carboxylic Acid Aldol Reaction.

    PubMed

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

    2016-05-01

    The first carboxylic acid selective aldol reaction mediated by boron compounds and a mild organic base (DBU) was developed. Inclusion of electron-withdrawing groups in the amino acid derivative ligands reacted with BH3·SMe2 forms a boron promoter with increased Lewis acidity at the boron atom and facilitated the carboxylic acid selective enolate formation, even in the presence of other carbonyl groups such as amides, esters, ketones, or aliphatic aldehydes. The remarkable ligand effect led to the broad substrate scope including biologically relevant compounds. PMID:27104352

  19. The dietary branched chain amino acid requirements of hybrid striped bass(Morone chrysops x M. saxatilis)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The requirements for branched chain amino acids (BCAAs) are unknown in hybrid striped bass and necessary for formulating efficient and nutritious diets. Moreover, the dietary balance among these three amino acids can substantially influence the performance of meat animals fed those diets. The diet...

  20. Correction: Mesoporous hybrid material composed of Mn3O4 nanoparticles on nitrogen-doped graphene for highly efficient oxygen reduction reaction.

    PubMed

    Duan, Jingjing; Zheng, Yao; Chen, Sheng; Tang, Youhong; Jaroniec, Mietek; Qiao, Shizhang

    2016-05-21

    Correction for 'Mesoporous hybrid material composed of Mn3O4 nanoparticles on nitrogen-doped graphene for highly efficient oxygen reduction reaction' by Jingjing Duan et al., Chem. Commun., 2013, 49, 7705-7707. PMID:27072341

  1. Nucleic acid hybridization for measurement of effects of antiviral compounds on human cytomegalovirus DNA replication.

    PubMed Central

    Gadler, H

    1983-01-01

    A nucleic acid hybridization technique has been developed to study the effect of different antiviral compounds on the replication of human cytomegalovirus in vitro. One laboratory strain of human cytomegalovirus, Ad. 169, and six clinical isolates were studied. Doses needed for 50% inhibition of viral DNA replication were calculated for foscarnet, acyclovir, and arabinosyladenine. The mean 50% inhibition dose values obtained were 179 microM for foscarnet, 82 microM for acyclovir, and 44 microM for arabinosyladenine. This method yields values that agree with earlier reports, and it offers great advantages over usual methods to date for studying inhibition of viral DNA replication. Images PMID:6314892

  2. A novel chaotic based image encryption using a hybrid model of deoxyribonucleic acid and cellular automata

    NASA Astrophysics Data System (ADS)

    Enayatifar, Rasul; Sadaei, Hossein Javedani; Abdullah, Abdul Hanan; Lee, Malrey; Isnin, Ismail Fauzi

    2015-08-01

    Currently, there are many studies have conducted on developing security of the digital image in order to protect such data while they are sending on the internet. This work aims to propose a new approach based on a hybrid model of the Tinkerbell chaotic map, deoxyribonucleic acid (DNA) and cellular automata (CA). DNA rules, DNA sequence XOR operator and CA rules are used simultaneously to encrypt the plain-image pixels. To determine rule number in DNA sequence and also CA, a 2-dimension Tinkerbell chaotic map is employed. Experimental results and computer simulations, both confirm that the proposed scheme not only demonstrates outstanding encryption, but also resists various typical attacks.

  3. Different kinetic behaviors for unimolecular and bimolecular ester hydrolysis reactions in strongly acidic microemulsions.

    PubMed

    Fernández, E; García-Río, L; Méndez-Pérez, M; Rodríguez-Dafonte, P

    2009-07-01

    Replacing the counterion in sodium bis(2-ethylhexyl)sulfosuccinate with H(+) allows strongly acidic microemulsions to be obtained. These systems are the only known colloidal medium in which it is possible to reach local concentrations of acid, expressed as Hammett acidity function (H(0)), lower than H(0) = -0.2, which corresponds to a concentration of acid above 1 M in aqueous solution. In the present work, there has been analyzed the influence of this type of microemulsion on the acid hydrolysis of two esters derived from picolinic acid: 4-nitrophenylpicolinate (NPP) and 2,4-dinitrophenylpicolinate (DNPP). The reaction rate for NPP and DNPP increases up to 16 times on increasing the size of the aqueous nanocore of the microemulsion, which supposes an experimental behavior opposed to the one observed for the hydrolysis of nitrophenylacetate (NPA). The key to this differentiated behavior of NPP and DNPP resides in the fact that the rate-determining step for the acid hydrolysis mechanism is the water addition to the protonated ester. The reaction rate increases on increasing the nucleophilicity of water; that is, on increasing W (W = [H(2)O]/[surfactant]). Therefore, the acid hydrolysis of esters in strongly acidic microemulsions presents an A2 mechanism when reactivity increases with W, and an A1 mechanism if it decreases with W. PMID:19518107

  4. Oxygen dependency of one-electron reactions generating ascorbate radicals and hydrogen peroxide from ascorbic acid.

    PubMed

    Boatright, William L

    2016-04-01

    The effect of oxygen on the two separate one-electron reactions involved in the oxidation of ascorbic acid was investigated. The rate of ascorbate radical (Asc(-)) formation (and stability) was strongly dependent on the presence of oxygen. A product of ascorbic acid oxidation was measurable levels of hydrogen peroxide, as high as 32.5 μM from 100 μM ascorbic acid. Evidence for a feedback mechanism where hydrogen peroxide generated during the oxidation of ascorbic acid accelerates further oxidation of ascorbic acid is also presented. The second one-electron oxidation reaction of ascorbic acid leading to the disappearance of Asc(-) was also strongly inhibited in samples flushed with argon. In the range of 0.05-1.2 mM ascorbic acid, maximum levels of measurable hydrogen peroxide were achieved with an initial concentration of 0.2 mM ascorbic acid. Hydrogen peroxide generation was greatly diminished at ascorbic acid levels of 0.8 mM or above. PMID:26593628

  5. Multicomponent Cascade Reactions of Unprotected Ketoses and Amino Acids--Access to a Defined Configured Quaternary Stereogenic Center.

    PubMed

    Richter, Celin; Nguyen Trung, Minh; Mahrwald, Rainer

    2015-11-01

    A highly stereoselective multicomponent cascade reaction of ketones with unprotected amino acids was developed. This operationally simple methodology was expanded to reactions of unprotected ketohexoses and unprotected amino acids. By the careful choice of amino acid and isonitrile, an optional access to all possible enantiomers is given. PMID:26451463

  6. 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.

  7. 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.

  8. New method for spectrophotometric determination of quinones and barbituric acid through their reaction. A kinetic study

    NASA Astrophysics Data System (ADS)

    Medien, H. A. A.

    1996-11-01

    A new and sensitive spectrophotometric method is described for the determination of p-benzoquinone, p-chloranil and 1.4-naphthoquinone. The method is based on the reaction between quinones and barbituric acid, by which a color is developed with maximum absorption between 485 and 555 nm in 50% methyl alcohol-water mixture. The absorption of the product obeys Beer's law within the concentration range 0.025-05 mM of orginal quinone. The kinetics of the reaction between p-benzoquinone and barbituric acid was studied in a range of methyl alcohol-water mixtures. The reaction follows overall second order kinetics, first order in each of the reactants. The rate increases with increasing dielectric constant. The method was applied for determination of barbituric acid with p-benzoquinone in the concentration range of 0.025-0.345 mM. Other barbiturates do not interfere.

  9. Hydrolysis reaction of 2,4-dichlorophenoxyacetic acid. A kinetic and computational study

    NASA Astrophysics Data System (ADS)

    Romero, Jorge Marcelo; Jorge, Nelly Lidia; Grand, André; Hernández-Laguna, Alfonso

    2015-10-01

    The degradation of the 2,4-dichlorophenoxyacetic acid in aqueous solution is an hydrolysis reaction. Two products are identified: 2,4-dichlorophenol and glycolic acid. Reaction is investigated as a function of pH and temperature, and it is first-order kinetics and pH-dependent. Reaction is modeled in gas phase, where a proton catalyses the reaction. Critical points of PES are calculated at B3LYP/6-311++G(3df,2p), and aug-cc-pvqz//6-311++G(3df,2p) levels plus ZPE at 6-311++G(3df,2p) level. The activation barrier is 21.2 kcal/mol. Theoretical results agree with the experimental results. A second mechanism related with a Cl2Phsbnd Osbnd CH2sbnd COOH⋯H2O complex is found, but with a rate limiting step of 38.4 kcal/mol.

  10. Tartaric Acid-Assisted Self-Assembly of Hybrid Block Copolymer Composites

    NASA Astrophysics Data System (ADS)

    Yao, Li; Lin, Ying; Watkins, James

    2014-03-01

    Enantiopure tartaric acid was used as an additive to increase the segregation strength of poly(ethylene oxide-block-tert-butyl acrylate) (PEO-b-PtBA) copolymers through strong, selective interactions with one of the polymer chain segments. Addition of tartaric acid to PEO-b-PtBA exhibiting cylindrical morphologies resulted in the formation of helical superstructures as observed by transmission electron microscopy. It was also found that this small acid additive can also enable phase-selective ultra-high loading of nanoparticles (NPs) into target domains of the block copolymer composites. The loading of tartaric acid can increase enthalpically favorable interactions between the nanoparticle ligands and the host domain and mitigate entropic penalties associated with NP incorporation into the target domain. A metal content of over 40 weight percent by mass of the resulting well ordered composites was achieved as measured by thermal gravimetric analysis in PEO-b-PtBA/tartaric acid/4-hydroxythiophenol functionalized Au NP hybrid system. Funding from Center for Hierarchical Manufacturing (CHM); Facility support from Materials Research Science and Engineering Center at UMass Amherst.

  11. 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 (α1 → 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

  12. Kinetics and Quantitative Structure—Activity Relationship Study on the Degradation Reaction from Perfluorooctanoic Acid to Trifluoroacetic Acid

    PubMed Central

    Gong, Chen; Sun, Xiaomin; Zhang, Chenxi; Zhang, Xue; Niu, Junfeng

    2014-01-01

    Investigation of the degradation kinetics of perfluorooctanoic acid (PFOA) has been carried out to calculate rate constants of the main elementary reactions using the multichannel Rice-Ramsperger-Kassel-Marcus theory and canonical variational transition state theory with small-curvature tunneling correction over a temperature range of 200~500 K. The Arrhenius equations of rate constants of elementary reactions are fitted. The decarboxylation is role step in the degradation mechanism of PFOA. For the perfluorinated carboxylic acids from perfluorooctanoic acid to trifluoroacetic acid, the quantitative structure–activity relationship of the decarboxylation was analyzed with the genetic function approximation method and the structure–activity model was constructed. The main parameters governing rate constants of the decarboxylation reaction from the eight-carbon chain to the two-carbon chain were obtained. As the structure–activity model shows, the bond length and energy of C1–C2 (RC1–C2 and EC1–C2) are positively correlated to rate constants, while the volume (V), the energy difference between EHOMO and ELUMO (ΔE), and the net atomic charges on atom C2 (QC2) are negatively correlated. PMID:25196516

  13. Transition-metal-free cascade reaction of α-halo-N-tosylhydrazones, indoles and arylboronic acids.

    PubMed

    Wu, Guojiao; Deng, Yifan; Luo, Haiqing; Zhou, Junliang; Li, Tianjiao; Zhang, Yan; Wang, Jianbo

    2016-04-18

    α-Halo-N-tosylhydrazones are employed as reagents for the formation of multiple carbon-carbon bonds in the three-component reactions. In this transformation, a strategy has been designed to generate the diazo intermediate by using a nucleophile to react with the azoalkene intermediate generated in situ from the α-halo-N-tosylhydrazone. The diazo intermediate thus generated further undergoes transition-metal-free C-C bond forming reaction with arylboronic acids. PMID:27001930

  14. The curing reaction study of the active material in the lead-acid battery

    NASA Astrophysics Data System (ADS)

    Laruelle, S.; Grugeon-Dewaele, S.; Torcheux, L.; Delahaye-Vidal, A.

    A study of the curing reaction involved in the positive plate of the lead-acid battery has been undertaken. The variation of the different parameters of the curing reaction has shown the possibility of changing the 4BS needles dimensions. In particular, the addition of a surfactant agent, namely the polyvinylpyrrolidone, to the reagents allows the obtention of tailor-made 4BS particles useable in the industrial preparation of the positive plates.

  15. Biosynthesis of the mycotoxin tenuazonic acid by a fungal NRPS-PKS hybrid enzyme.

    PubMed

    Yun, Choong-Soo; Motoyama, Takayuki; Osada, Hiroyuki

    2015-01-01

    Tenuazonic acid (TeA) is a well-known mycotoxin produced by various plant pathogenic fungi. However, its biosynthetic gene has been unknown to date. Here we identify the TeA biosynthetic gene from Magnaporthe oryzae by finding two TeA-inducing conditions of a low-producing strain. We demonstrate that TeA is synthesized from isoleucine and acetoacetyl-coenzyme A by TeA synthetase 1 (TAS1). TAS1 is a unique non-ribosomal peptide synthetase and polyketide synthase (NRPS-PKS) hybrid enzyme that begins with an NRPS module. In contrast to other NRPS/PKS hybrid enzymes, the PKS portion of TAS1 has only a ketosynthase (KS) domain and this domain is indispensable for TAS1 activity. Phylogenetic analysis classifies this KS domain as an independent clade close to type I PKS KS domain. We demonstrate that the TAS1 KS domain conducts the final cyclization step for TeA release. These results indicate that TAS1 is a unique type of NRPS-PKS hybrid enzyme. PMID:26503170

  16. Biosynthesis of the mycotoxin tenuazonic acid by a fungal NRPS–PKS hybrid enzyme

    PubMed Central

    Yun, Choong-Soo; Motoyama, Takayuki; Osada, Hiroyuki

    2015-01-01

    Tenuazonic acid (TeA) is a well-known mycotoxin produced by various plant pathogenic fungi. However, its biosynthetic gene has been unknown to date. Here we identify the TeA biosynthetic gene from Magnaporthe oryzae by finding two TeA-inducing conditions of a low-producing strain. We demonstrate that TeA is synthesized from isoleucine and acetoacetyl-coenzyme A by TeA synthetase 1 (TAS1). TAS1 is a unique non-ribosomal peptide synthetase and polyketide synthase (NRPS–PKS) hybrid enzyme that begins with an NRPS module. In contrast to other NRPS/PKS hybrid enzymes, the PKS portion of TAS1 has only a ketosynthase (KS) domain and this domain is indispensable for TAS1 activity. Phylogenetic analysis classifies this KS domain as an independent clade close to type I PKS KS domain. We demonstrate that the TAS1 KS domain conducts the final cyclization step for TeA release. These results indicate that TAS1 is a unique type of NRPS–PKS hybrid enzyme. PMID:26503170

  17. Hybrid polymeric hydrogels via peptide nucleic acid (PNA)/DNA complexation.

    PubMed

    Chu, Te-Wei; Feng, Jiayue; Yang, Jiyuan; Kope?ek, Jind?ich

    2015-12-28

    This work presents a new concept in hybrid hydrogel design. Synthetic water-soluble N-(2-hydroxypropyl)methacrylamide (HPMA) polymers grafted with multiple peptide nucleic acids (PNAs) are crosslinked upon addition of the linker DNA. The self-assembly is mediated by the PNA-DNA complexation, which results in the formation of hydrophilic polymer networks. We show that the hydrogels can be produced through two different types of complexations. Type I hydrogel is formed via the PNA/DNA double-helix hybridization. Type II hydrogel utilizes a unique "P-form" oligonucleotide triple-helix that comprises two PNA sequences and one DNA. Microrheology studies confirm the respective gelation processes and disclose a higher critical gelation concentration for the type I gel when compared to the type II design. Scanning electron microscopy reveals the interconnected microporous structure of both types of hydrogels. Type I double-helix hydrogel exhibits larger pore sizes than type II triple-helix gel. The latter apparently contains denser structure and displays greater elasticity as well. The designed hybrid hydrogels have potential as novel biomaterials for pharmaceutical and biomedical applications. PMID:26394062

  18. Fibrillar networks of glycyrrhizic acid for hybrid nanomaterials with catalytic features.

    PubMed

    Saha, Abhijit; Adamcik, Jozef; Bolisetty, Sreenath; Handschin, Stephan; Mezzenga, Raffaele

    2015-04-27

    Self-assembly of the naturally occurring sweetening agent, glycyrrhizic acid (GA) in water is studied by small-angle X-ray scattering and microscopic techniques. Statistical analysis on atomic force microscopy images reveals the formation of ultralong GA fibrils with uniform thickness of 2.5 nm and right-handed twist with a pitch of 9 nm, independently of GA concentration. Transparent nematic GA hydrogels are exploited to create functional hybrid materials. Two-fold and three-fold hybrids are developed by introducing graphene oxide (GO) and in situ-synthesized gold nanoparticles (Au NPs) in the hydrogel matrix for catalysis applications. In the presence of GO, the catalytic efficiency of Au NPs in the reduction of p-nitrophenol to p-aminophenol is enhanced by 2.5 times. Gold microplate single crystals are further synthesized in the GA hydrogel, expanding the scope of these hybrids and demonstrating their versatility in materials design. PMID:25759108

  19. Sequential injection analysis system for the sandwich hybridization-based detection of nucleic acids.

    PubMed

    Edwards, Katie A; Baeumner, Antje J

    2006-03-15

    A sequential injection analysis lab-on-valve (SIA-LOV) system was developed for the specific detection of single-stranded nucleic acid sequences via sandwich hybridization of specific DNA probes to the target sequence. One DNA probe was tagged with fluorescein; the other was biotinylated and immobilized to streptavidin-coated porous beads. The system was optimized with respect to buffer composition, length of hybridization and wash steps, and volumes and concentrations of components used. On-bead oligonucleotide hybridization was studied using UV detection at 260 nm, while a final dose response curve was quantified using fluorescence detection. A dynamic range of 1-1000 pmol was obtained for a synthetic DNA sequence that was homologous to a segment in the B. anthracis atxA mRNA. A within-day variation of 7.2% and a day-to-day variation of 9.9% was observed. Each analysis was completed within 20 min. Subsequently, the system was applied to the detection of atxA mRNA expressed in a surrogate organism and amplified using NASBA. The SIA-LOV will find its application in routine laboratory-based analysis of specific single-stranded DNA/RNA sequences. Future improvements will include the integration of dye-encapsulating liposomes for signal enhancement used in lieu of the single fluorophore-labeled probe in order to lower the limit of detection. PMID:16536433

  20. 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, Diane 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.

  1. Chiral Phosphoric Acid Catalyzed Asymmetric Ugi Reaction by Dynamic Kinetic Resolution of the Primary Multicomponent Adduct.

    PubMed

    Zhang, Yun; Ao, Yu-Fei; Huang, Zhi-Tang; Wang, De-Xian; Wang, Mei-Xiang; Zhu, Jieping

    2016-04-18

    Reaction of isonitriles with 3-(arylamino)isobenzofuran-1(3H)-ones in the presence of a catalytic amount of an octahydro (R)-binol-derived chiral phosphoric acid afforded 3-oxo-2-arylisoindoline-1-carboxamides in high yields with good to high enantioselectivities. An enantioselective Ugi four-center three-component reaction of 2-formylbenzoic acids, anilines, and isonitriles was subsequently developed for the synthesis of the same heterocycle. Mechanistic studies indicate that the enantioselectivity results from the dynamic kinetic resolution of the primary Ugi adduct, rather than from the C-C bond-forming process. The resulting heterocycle products are of significant medicinal importance. PMID:26997306

  2. 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

  3. 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.

  4. The influence of SiO2 doping on the microstructure and photochromic behavior of phosphomolybdic acid/polyvinyl pyrrolidone hybrid films

    NASA Astrophysics Data System (ADS)

    Dong, Qi; Wang, Xiang-Yu; Lu, Ya-Mei; Sun, Hai-Yan; Meng, Qing-Ling; Liu, Su-Ling; Feng, Wei; Han, Xiang-Kui

    2014-10-01

    New hybrid films were synthesized by SiO2 doping into phosphomolybdic acid (PMoA)/polyvinyl pyrrolidone (PVPd) composite system, and the effect of SiO2 doping on microstructure and photochromic properties was studied via atomic force microscope (AFM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectra (UV-vis) and X-ray photoelectron spectroscopy (XPS). The hybrid film surface with dome projection changed rough from smooth after SiO2 doping. The vibrational spectra of FT-IR verified that component of the heteropolyacids and the polymer did not changed, the vibration bands were expanded and had shifted by a few cm-1, and changed interaction between the acid and the polymer after SiO2 doping. The hybrid film exhibited a good photochromic property, which changed from colorless to blue under UV irradiation. The color change intensity of SiO2/PMoA/PVPd film was 1.48 times stronger than that of PMoA/PVPd under the same condition. XPS results indicated that the amount of PMoA in photo-reductive reaction was increased after SiO2 doping.

  5. Reactions of Chemically Activated Formic Acid Formed via HĊO + ȮH.

    PubMed

    Döntgen, Malte; Leonhard, Kai

    2016-03-24

    The chemistry of formyl radicals plays an important role in the kinetic modeling of oxygenated hydrocarbons. Here, the fate of rovibrationally excited formic acid produced via HĊO + ȮH is evaluated in a RRKM/Master Equation study. For that purpose, the HĊO + ȮH potential energy surface is studied theoretically using high-level quantum mechanics. Direct reaction from HĊO + ȮH to the bimolecular products is found to dominate for most relevant conditions due to formic acid well-skipping. The kinetics of these well-skipping reactions can only be evaluated when including the unimolecular intermediate, formic acid. Further, hydrogen abstraction from rovibrationally excited formic acid is found to be important at low-temperature conditions and for high radical concentrations. PMID:26954251

  6. Organic-inorganic hybrids prepared by carboxylic acid solvolysis: Planar waveguides

    NASA Astrophysics Data System (ADS)

    Molina, C.; Maia, L. J. Q.; Messaddeq, Y.; Ribeiro, S. J. L.

    2012-03-01

    Organic-inorganic hybrid planar waveguides based on the UV sensitive methacryloxypropyltrimethoxysilane (MAPTMS) were prepared through non-hydrolytic sol-gel process by carboxylic acid solvolysis and also containing the fluormonomer precursor 2,2,3,3-tetrafluorpropylmethacrylate (TFPM) and methacrylic acid (MA) modified zirconium alkoxide (ZPO). The absence of water and the incorporation of Csbnd F bonding containing precursor contributed to obtain low optical loss in the final material. Characterization techniques included 29Si-NMR, vibrational spectroscopy and optical characterization of the waveguides with measurements of refractive index, thickness, propagating modes and attenuation coefficient by m-lines prism coupling technique at 632.8, 543.5 and, 1550 nm were performed. The surface of the films was investigated by roughness (RMS) and contact angle measurements.

  7. Reactions of stabilized aliphatic carbanions with esters of formic acid in the gas phase.

    PubMed

    Wileńska, Beata; Świder, Paweł; Danikiewicz, Witold

    2015-01-01

    The reactions of nitromethane, acetonitrile, and ethyl acetate carbanions with formic acid esters were investigated in the gas phase by mass spectrometry and quantum chemical calculations. It was found that the carbanion of nitromethane practically does not react with formic acid esters and only traces of the Claisen- type addition-elimination reaction product were observed. In the case of the deprotonated acetonitrile, the Claisen-type condensation that yielded the carbanion of cyanoacetaldehyde proceeded almost quantitatively for all the studied formates. Other products, like the Riveros reaction product, were observed in minor amounts. The ethyl acetate carbanion reacts with formates in a much more complex way because it decomposes in a collision cell, yielding the deprotonated ketene anion, which also can react with formic acid esters. Consequently, the Claisen condensation reaction products of both anions were observed as well as the products of other reactions. All the proposed reaction pathways were confirmed by quantum chemical calculations, including the transition-state energies. PMID:26307733

  8. 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.

  9. Determination of Free Fatty Acids and Triglycerides by Gas Chromatography Using Selective Esterification Reactions

    SciTech Connect

    Kail, Brian W.; Link, Dirk D.; Morreale, Bryan D

    2012-11-01

    A method for selectively determining both free fatty acids (FFA) and triacylglycerides (TAGs) in biological oils was investigated and optimized using gas chromatography after esterification of the target species to their corresponding fatty acid methyl esters (FAMEs). The method used acid catalyzed esterification in methanolic solutions under conditions of varying severity to achieve complete conversion of more reactive FFAs while preserving the concentration of TAGs. Complete conversion of both free acids and glycerides to corresponding FAMEs was found to require more rigorous reaction conditions involving heating to 120°C for up to 2 h. Method validation was provided using gas chromatography–flame ionization detection, gas chromatography–mass spectrometry, and liquid chromatography–mass spectrometry. The method improves on existing methods because it allows the total esterified lipid to be broken down by FAMEs contributed by FFA compared to FAMEs from both FFA and TAGs. Single and mixed-component solutions of pure fatty acids and triglycerides, as well as a sesame oil sample to simulate a complex biological oil, were used to optimize the methodologies. Key parameters that were investigated included: HCl-to-oil ratio, temperature and reaction time. Pure free fatty acids were found to esterify under reasonably mild conditions (10 min at 50°C with a 2.1:1 HCl to fatty acid ratio) with 97.6 ± 2.3% recovery as FAMEs, while triglycerides were largely unaffected under these reaction conditions. The optimized protocol demonstrated that it is possible to use esterification reactions to selectively determine the free acid content, total lipid content, and hence, glyceride content in biological oils. This protocol also allows gas chromatography analysis of FAMEs as a more ideal analyte than glyceride species in their native state.

  10. [The role of L-ascorbic acid in free radical reactions].

    PubMed

    Kleszczewska, Ewa

    2002-01-01

    L-ascorbic acid is one of the basic vitamins, necessary to the normal growth and behaviour of organisms. The primary of this review is to present the chemical characteristics of this substance and to discuss its relation to various biological functions of vitamin C, mainly as an antioxidant barrier (we analysed product of reaction between phenothiazine derivative and L-ascorbic acid). PMID:12587430

  11. Miniature reaction chamber and devices incorporating same

    DOEpatents

    Mathies, Richard A.; Woolley, Adam T.

    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.

  12. Photon-counting optical fiber biosensor for the characterization of nucleic acid hybridization

    NASA Astrophysics Data System (ADS)

    Lu, Hua; Zhao, Yujie; Ma, Jianmin; Lu, Zukang; Lu, Zu-Hong

    1999-09-01

    Optical fiber biosensors offer great promise for rapid and sensitive detection of a variety of chemical and biological analyte. In this paper, we report our progress in developing an optical fiber biosensor for the characterization of solid phase nucleic acid hybridization. The principle of the measurement is based on the combination of photon counting and laser induced fluorescence in the evanescent field on the optical fiber surface. We used long, fused silica fibers that had several centimeters of cladding removed along the distal end for the fabrication of sensor probe. 5'-amino-terminal oligonucleotide probes were covalently immobilized via glutaraldehyde cross- linking to an aminosilane on the exposed fiber core to form a thin layer of oligonucleotide probes. The evanescent excitation of fluorescence was achieved through the evanescent wave penetrating into the oligonucleotide probes layer when an Ar ion laser beam was guided in the optical fiber. In situ hybridization of 5'-fluorescein isothiocyanate (FITC)-labeled complementary oligonucleotides to their immobilized probes was monitored at the proximal end of the sensing fiber through the fluorescent signal which generated in the evanescent wave region of the uncladded portion as they coupled back to the fiber core. Hybridization specificity was tested by addition of fluorescein isothiocyanate (FITC)-labeled noncomplementary oligonucleotides to the immobilized probes. Regeneration of the surface-immobilized probe was possible, allowing reuse without a significant loss of hybridization activity. Dilution experiments showed an apparent lower limit of detection at 1 nM oligonucleotides. This performance was comparable to other previously reported DNA biosensors.

  13. Crude palm oil from interspecific hybrid Elaeis oleifera×Elaeis guineensis: fatty acid regiodistribution and molecular species of glycerides.

    PubMed

    Mozzon, Massimo; Pacetti, Deborah; Lucci, Paolo; Balzano, Michele; Frega, Natale Giuseppe

    2013-11-01

    The composition and structure of triacylglycerols (TAGs) and partial glycerides of crude palm oil obtained from interspecific hybrid Elaeis oleifera×Elaeis guineensis, grown in Colombia, were fully characterised and compared to data obtained by analysing crude African palm oil. Hybridisation appears to substantially modify the biosynthesis of fatty acids (FAs) rather than their assembly in TAGs. In fact, total FAs analysis showed significant differences between these two types of oil, with hybrid palm oil having a higher percentage of oleic acid (54.6 ± 1.0 vs 41.4 ± 0.3), together with a lower saturated fatty acid content (33.5 ± 0.5 vs 47.3 ± 0.1), while the percentage of essential fatty acid, linoleic acid, does not undergo significant changes. Furthermore, 34 TAG types were identified, with no qualitative differences between African and E. guineensis×E. oleifera hybrid palm oil samples. Short and medium chain FAs (8:0, 10:0, 12:0, 14:0) were utilised, together, to build a restricted number of TAG molecular species. Oil samples from the E. guineensis×E. oleifera hybrid showed higher contents of monosaturated TAGs (47.5-51.0% vs 36.7-37.1%) and triunsaturated TAGs (15.5-15.6% vs 5.2-5.4%). The sn-2 position of TAGs in hybrid palm oil was shown to be predominantly esterified with oleic acid (64.7-66.0 mol% vs 55.1-58.2 mol% in African palm oil) with only 10-15% of total palmitic acid and 6-20% of stearic acid acylated in the secondary position. The total amount of diacylglycerols (DAGs) was in agreement with the values of free acidity; DAG types found were in agreement with the representativeness of different TAG species. PMID:23768354

  14. 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 (e) and device field-effect mobility (f), two new parameters were defined to interpret the effect of L on the FET response to hybridization. Our results indicate that FETs with ?300 m long SWCNT exhibited the most appreciable response to hybridization, which complied with the variation trend in response to the newly defined parameters. PMID:25551036

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

    PubMed Central

    An, Jianing; Zhang, Yani; Wong, Chee How

    2014-01-01

    Summary 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 (e) and device field-effect mobility (f), two new parameters were defined to interpret the effect of L on the FET response to hybridization. Our results indicate that FETs with ?300 m long SWCNT exhibited the most appreciable response to hybridization, which complied with the variation trend in response to the newly defined parameters. PMID:25551036

  16. Fatty acid membrane assembly on coacervate microdroplets as a step towards a hybrid protocell model

    NASA Astrophysics Data System (ADS)

    Dora Tang, T.-Y.; Rohaida Che Hak, C.; Thompson, Alexander J.; Kuimova, Marina K.; Williams, D. S.; Perriman, Adam W.; Mann, Stephen

    2014-06-01

    Mechanisms of prebiotic compartmentalization are central to providing insights into how protocellular systems emerged on the early Earth. Protocell models are based predominantly on the membrane self-assembly of fatty-acid vesicles, although membrane-free scenarios that involve liquid-liquid microphase separation (coacervation) have also been considered. Here we integrate these alternative models of prebiotic compartmentalization and develop a hybrid protocell model based on the spontaneous self-assembly of a continuous fatty-acid membrane at the surface of preformed coacervate microdroplets prepared from cationic peptides/polyelectrolytes and adenosine triphosphate or oligo/polyribonucleotides. We show that the coacervate-supported membrane is multilamellar, and mediates the selective uptake or exclusion of small and large molecules. The coacervate interior can be disassembled without loss of membrane integrity, and fusion and growth of the hybrid protocells can be induced under conditions of high ionic strength. Our results highlight how notions of membrane-mediated compartmentalization, chemical enrichment and internalized structuration can be integrated in protocell models via simple chemical and physical processes.

  17. 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

  18. Hybrid Processes Combining Photocatalysis and Ceramic Membrane Filtration for Degradation of Humic Acids in Saline Water

    PubMed Central

    Song, Lili; Zhu, Bo; Gray, Stephen; Duke, Mikel; Muthukumaran, Shobha

    2016-01-01

    This study explored the combined effects of photocatalysis with ceramic membrane filtration for the removal of humic acid in the presence of salt; to simulate saline wastewater conditions. The effects of operating parameters, such as salinity and TiO2 concentration on permeate fluxes, total organic carbon (TOC), and UV absorbance removal, were investigated. The interaction between the humic acids and TiO2 photocatalyst played an important role in the observed flux change during ceramic membrane filtration. The results for this hybrid system showed that the TOC removal was more than 70% for both without NaCl and with the 500 ppm NaCl concentration, and 62% and 66% for 1000 and 2000 ppm NaCl concentrations. The reduction in UV absorbance was more complete in the absence of NaCl compared to the presence of NaCl. The operation of the integrated photoreactor-ceramic membrane filter over five repeat cycles is described. It can be concluded that the overall removal performance of the hybrid system was influenced by the presence of salts, as salt leads to agglomeration of TiO2 particles by suppressing the stabilising effects of electrostatic repulsion and thereby reduces the effective surface contact between the pollutant and the photocatalyst. PMID:26938568

  19. Hybrid Processes Combining Photocatalysis and Ceramic Membrane Filtration for Degradation of Humic Acids in Saline Water.

    PubMed

    Song, Lili; Zhu, Bo; Gray, Stephen; Duke, Mikel; Muthukumaran, Shobha

    2016-01-01

    This study explored the combined effects of photocatalysis with ceramic membrane filtration for the removal of humic acid in the presence of salt; to simulate saline wastewater conditions. The effects of operating parameters, such as salinity and TiO₂ concentration on permeate fluxes, total organic carbon (TOC), and UV absorbance removal, were investigated. The interaction between the humic acids and TiO₂ photocatalyst played an important role in the observed flux change during ceramic membrane filtration. The results for this hybrid system showed that the TOC removal was more than 70% for both without NaCl and with the 500 ppm NaCl concentration, and 62% and 66% for 1000 and 2000 ppm NaCl concentrations. The reduction in UV absorbance was more complete in the absence of NaCl compared to the presence of NaCl. The operation of the integrated photoreactor-ceramic membrane filter over five repeat cycles is described. It can be concluded that the overall removal performance of the hybrid system was influenced by the presence of salts, as salt leads to agglomeration of TiO₂ particles by suppressing the stabilising effects of electrostatic repulsion and thereby reduces the effective surface contact between the pollutant and the photocatalyst. PMID:26938568

  20. Palm fatty acid biodiesel: process optimization and study of reaction kinetics.

    PubMed

    Yadav, Praveen K S; Singh, Onkar; Singh, R P

    2010-01-01

    The relatively high cost of refined oils render the resulting fuels unable to compete with petroleum derived fuel. In this study, biodiesel is prepared from palm fatty acid (PFA) which is a by-product of palm oil refinery. The process conditions were optimized for production of palm fatty acid methyl esters. A maximum conversion of 94.4% was obtained using two step trans-esterification with 1:10 molar ratio of oil to methanol at 65°C. Sulfuric acid and Sodium hydroxide were used as acid and base catalyst respectively. The composition of fatty acid methyl esters (FAME) obtained was similar to that of palm oil. The biodiesel produced met the established specifications of biodiesel of American Society for Testing and Materials (ASTM). The kinetics of the trans-esterification reaction was also studied and the data reveals that the reaction is of first order in fatty acid and methanol (MeOH) and over all the reaction is of second order. PMID:20972357

  1. Design of hybrid multimodal poly(lactic-co-glycolic acid) polymer nanoparticles for neutrophil labeling, imaging and tracking

    NASA Astrophysics Data System (ADS)

    Qiu, Yuan; Palankar, Raghavendra; Echeverría, María; Medvedev, Nikolay; Moya, Sergio E.; Delcea, Mihaela

    2013-11-01

    Poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) incorporating quantum dots (QDs), superparamagnetic iron oxide nanoparticles (SPIONs) and gold (Au) NPs for neutrophil labeling were fabricated via the w/o/w double emulsion method. QDs and SPIONs were entrapped in the PLGA core during emulsification while Au NPs were assembled on top of the PLGA NPs via electrostatic interactions. Transmission Electron Microscopy, Scanning Electron Microscopy and Confocal Scanning Laser Microscopy (CLSM) were applied to characterize the hybrid PLGA NPs. The uptake of the hybrid PLGA NPs by human neutrophils was studied by Flow Cytometry and confocal microscopy. In addition, the induction of reactive oxygen species (ROS) in neutrophils after incubation with the hybrid PLGA NPs was assessed. Magnetophoresis experiments showed that neutrophils with internalized hybrid PLGA NPs can be effectively laterally displaced towards the magnetic field. Magnetic Resonance Imaging of the hybrid PLGA NPs resulted in images with a contrast enhancement linearly dependent on the concentration of the hybrid PLGA NPs. Research reported in this work is relevant for imaging, tracking and manipulating neutrophils and has potential for in vivo applications, e.g., tumor visualization and localized photothermal treatment.Poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) incorporating quantum dots (QDs), superparamagnetic iron oxide nanoparticles (SPIONs) and gold (Au) NPs for neutrophil labeling were fabricated via the w/o/w double emulsion method. QDs and SPIONs were entrapped in the PLGA core during emulsification while Au NPs were assembled on top of the PLGA NPs via electrostatic interactions. Transmission Electron Microscopy, Scanning Electron Microscopy and Confocal Scanning Laser Microscopy (CLSM) were applied to characterize the hybrid PLGA NPs. The uptake of the hybrid PLGA NPs by human neutrophils was studied by Flow Cytometry and confocal microscopy. In addition, the induction of reactive oxygen species (ROS) in neutrophils after incubation with the hybrid PLGA NPs was assessed. Magnetophoresis experiments showed that neutrophils with internalized hybrid PLGA NPs can be effectively laterally displaced towards the magnetic field. Magnetic Resonance Imaging of the hybrid PLGA NPs resulted in images with a contrast enhancement linearly dependent on the concentration of the hybrid PLGA NPs. Research reported in this work is relevant for imaging, tracking and manipulating neutrophils and has potential for in vivo applications, e.g., tumor visualization and localized photothermal treatment. Electronic supplementary information (ESI) available: TEM images of QDs, SPIONs and Au NPs; UV emission spectra of QDs and hybrid PLGA NPs; the EDX spectrum of PLGA_QD_SPION NPs; the size and zeta potential of hybrid PLGA NPs; magnetophoresis of neutrophils with hybrid particles (movie). See DOI: 10.1039/c3nr04013e

  2. Detection of Acidithiobacillus ferrooxidans in acid mine drainage environments using fluorescent in situ hybridization (FISH).

    PubMed

    Mahmoud, K K; Leduc, L G; Ferroni, G D

    2005-04-01

    An important microorganism of acid mine drainage (AMD) and bioleaching environments is Acidithiobacillus ferrooxidans which oxidizes ferrous iron and generates ferric iron, an oxidant. Most investigations to understand microbial aspects of sulfide mineral dissolution have focused on understanding physiological, metabolic, and genetic characteristics of A. ferrooxidans. In this study, a 16S rRNA oligonucleotide probe designated S-S-T.ferr-0584-a-A-18, and labeled at the 5'-end with indocarbocyanine dye (CY3), was used in a fluorescent in situ hybridization (FISH) procedure on pure cultures of nine isolates of A. ferrooxidans. These isolates were recovered from acid mine drainage and mining environments. The probe was also used to detect cells of A. ferrooxidans, recovered from AMD samples, growing on FeTSB and FeSo solid media in a FISH procedure. In addition, the presence of cells of A. ferrooxidans in an environmental water sample from an AMD site in Copper Cliff, Ontario, Canada was analyzed using the FISH technique. Probe specificity was first confirmed with A. ferrooxidans ATCC 19859 (positive control) and Acidithiobacillus thiooxidans ATCC 19377, Acidiphilium acidophilum ATCC 27807, and Lactobacillus plantarum ATCC 8014 (negative controls). Positive and negative control cells were also used to determine optimal stringency conditions for hybridizations with the probe. Cells of the nine isolates of A. ferrooxidans stained positive, although the fluorescent signal varied in intensity from isolate to isolate. Colonies of A. ferrooxidans from the environmental water sample of the AMD site were recovered only on FeTSB solid medium after 22 days of incubation. The probe was able to detect cells of A. ferrooxidans in a FISH procedure. However, no cells of A. ferrooxidans were detected in the AMD water sample without cultivation. Thus, probe S-S-T.ferr-0584-a-A-18 hybridized effectively with cells of A. ferrooxidans recovered from pure cultures but failed to directly detect cells of A. ferrooxidans in the AMD site. PMID:15676194

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

    SciTech Connect

    Caratzoulas, Stavros; Courtney, Timothy; Vlachos, Dionisios G.

    2011-01-01

    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.

  4. Predominance of human versus rat phenotype in the metabolic pathways for bile acid synthesis by hybrid WIF-B9 cells.

    PubMed

    Monte, M J; Badia, M D; Serrano, M A; Sacristan, M P; Cassio, D; Marin, J J

    2001-11-30

    The rat hepatoma-human fibroblast hybrid cell line WIF-B9 stably exhibits the structural and functional characteristics of normal differentiated hepatocytes. The abilities of these cells to synthesize bile acids and amidate them with glycine and taurine were investigated. The release of bile acids into the culture media over 72 h was assessed by gas chromatography-mass spectrometry. WIF-B9 cells were able to synthesize bile acids (1.10+/-0.17 nmol/mg protein) but less efficiently than rat hepatocytes in primary culture (2.19+/-0.19 nmol/mg protein; P<0.01). The patterns of major bile acid species produced by both types of cells were also different. Cholic acid (CA; 72%) and beta-muricholic acid (19%) were the major bile acids produced by rat hepatocytes, while chenodeoxycholic acid (CDCA) accounted for only 4.5% of total bile acids. In contrast, muricholic acids were absent, while CA (62%) and CDCA (34%) were the most abundant bile acids synthesized by WIF-B9 cells. Using reverse transcription-polymerase chain reaction and gene- and species-specific primers for key enzymes involved in bile acid synthesis, the expression of human, but not rat, orthologues of CYP7A1, CYP27, CYP8B and CYP7B1 was found in WIF-B9 cells. Induction of cell stress by serum deprivation did not change the amount of total bile acids synthesized by these cells, but an inversion of the CA-to-CDCA ratio from 1.8 to 0.3 together with a marked increase in the proportion of intermediate metabolites related to the acidic pathway was found. Using 500 microM radiolabeled CA and 2 mM of taurine or glycine, the ability to amidate CA over 48 h was determined by high performance liquid chromatography. Rat hepatocytes conjugated more than 90% CA with either amino acid, whereas this ability was very poor (< 2%) in WIF-B9 cells. Regarding the expression of enzymes and the products of bile acid synthesis, it may be concluded that the human phenotype predominates over that of the rat in WIF-B9 cells. Moreover, these cells are almost completely unable to further conjugate primary bile acids, which facilitates the manipulation of these steroids in analytical procedures. These characteristics make WIF-B9 cells a suitable in vitro model to carry out studies on bile acid synthesis by 'human-like' metabolic pathways. PMID:11750886

  5. Effect of Backbone Design on Hybridization Thermodynamics of Oligo-nucleic Acids: A Coarse-Grained Molecular Dynamics Simulation Study

    NASA Astrophysics Data System (ADS)

    Ghobadi, Ahmadreza F.; Jayaraman, Arthi

    DNA hybridization is the basis of various bio-nano technologies, such as DNA origami and assembly of DNA-functionalized nanoparticles. A hybridized double stranded (ds) DNA is formed when complementary nucleobases on hybridizing strands exhibit specific and directional hydrogen bonds through canonical Watson-Crick base-pairing interactions. In recent years, the need for cheaper alternatives and significant synthetic advances have driven design of DNA mimics with new backbone chemistries. However, a fundamental understanding of how these backbone modifications in the oligo-nucleic acids impact the hybridization and melting behavior of the duplex is still lacking. In this talk, we present our recent findings on impact of varying backbone chemistry on hybridization of oligo-nucleic acid duplexes. We use coarse-grained molecular dynamics simulations to isolate the effect of strand flexibility, electrostatic interactions and nucleobase spacing on the melting curves for duplexes with various strand sequences and concentrations. Since conjugation of oligo-nucleic acids with polymers serve as building blocks for thermo-responsive polymer networks and gels, we also present the effect of such conjugation on hybridization thermodynamics and polymer conformation.

  6. 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%.

  7. Fast and stable redox reactions of MnO2/CNT hybrid electrodes for dynamically stretchable pseudocapacitors

    NASA Astrophysics Data System (ADS)

    Gu, Taoli; Wei, Bingqing

    2015-07-01

    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.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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02310f

  8. Relationship between fatty acid profile and vitamin E content in maize hybrids (Zea mays L.).

    PubMed

    Goffman, F D; Böhme, T

    2001-10-01

    The balance between the vitamin E (tocochromanols) and polyunsaturated fatty acid (PUFA) contents mainly determines the susceptibility to lipid peroxidation and the storage stability of corn oil. In 1997, field experiments were conducted at two different locations to evaluate a collection of 30 corn hybrids for fatty acid profiles and tocochromanol contents. Hybrids differed significantly (p < 0.01) for major fatty acids, as well as for tocochromanol contents and composition. The major fatty acids were palmitic, oleic, and linoleic acids, whose contents were in the ranges 9.2-12.1%, 19.5-30.5%, and 53.0-65.3%, respectively. The tocopherol contents ranged as follows: alpha-tocopherol, 67-276 mg (kg of oil)(-1); beta-tocopherol, 0-20 mg (kg of oil)(-1); gamma-tocopherol, 583-1048 mg (kg of oil)(-1); delta-tocopherol, 12-71 mg (kg of oil)(-1); total tocopherol, 767-1344 mg (kg of oil)(-1). gamma-Tocopherol was the predominant derivative among all tocopherols. The tocotrienol contents were in the ranges 46-89, 53-164, and 99-230 mg (kg of oil)(-1) for alpha-, gamma-, and total tocotrienol contents, respectively. The tocotrienol profile was not characterized by the predominance of any tocotrienol homologue. alpha-Tocopherol was positively correlated with PUFA (r = 0.41) and with the vitamin E equivalent (vit E equiv) (r = 0.84), and it was not correlated with gamma-tocopherol. gamma-Tocopherol was highly correlated with total tocopherol and tocochromanol contents (r = 0.93 and r = 0.90, respectively), indicating that the contribution of this vitamer to the total tocochromanol content is the most important among all tocochromanols. The high positive correlation found between the vit E/PUFA ratio and the vit E equiv, as well as the absence of correlation between this ratio and PUFA indicates that a higher vit E/PUFA ratio can be easier achieved be increasing the vitamin E content than by modifying fatty acid profile in corn oil. PMID:11600056

  9. Deuteration of pentacene in benzoic acid: Monitoring the reaction kinetics via low-temperature optical spectroscopy

    SciTech Connect

    Corval, A.; Casalegno, R.; Astilean, S.; Trommsdorff, H.P.

    1992-06-25

    In the deuteration of pentacene in benzoic acid, this reaction is monitored via low-temperature optical spectroscopy to observe the proton-deuterium rate of exchange between the solvent and solute molecules. Of the 14 pentacene protons, 6 have an exchange rate 2 orders of magnitude greater than the remaining 8. 20 refs., 3 figs.

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

    PubMed

    Taylan, N; Gürbüz, H; Bulutcu, A N

    2007-07-01

    Colemanite is one of the most important boron minerals used for production of boric acid. Boric acid (H(3)BO(3)) is produced by the reaction of colemanite (2CaO.3B(2)O(3).5H(2)O) 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 H(2)SO(4) solution and on the precipitation of the gypsum during the reaction was investigated. Experiments have been carried out in a batch stirred vessel at 85 degrees C in the absence and presence of ultrasound. The stirring rates were chosen as 600 rpm (for 500-600 microm) and 800 rpm (for 1000-1180 microm) to provide a homogeneous suspension during the reaction. The boric acid and calcium ion concentrations in the solution were determined as a function of time. The results showed that ultrasound enhances the dissolution of colemanite and precipitation rate of the gypsum in the solution after 1h. It has been shown that the use of ultrasound decreases the size of gypsum crystals. PMID:17175191

  11. Spiro-annulation of barbituric acid derivatives and its analogs by ring-closing metathesis reaction.

    PubMed

    Kotha, Sambasivarao; Deb, Ashoke Chandra; Kumar, Ramanatham Vinod

    2005-02-15

    Barbituric acid 1 and related beta-dicarbonyl compounds were dialkenylated under the phase-transfer catalyst [e.g., benzyltriethylammonium chloride (BTEAC)] conditions to generate the diallylated products. These diallylated products were subjected to the ring-closing metathesis (RCM) reaction to deliver the corresponding spiro-annulated derivatives. PMID:15686908

  12. TiCl4-promoted multicomponent reaction: a new entry to functionalized alpha-amino acids.

    PubMed

    Ghosh, Arun K; Xu, Chun-Xiao; Kulkarni, Sarang S; Wink, Donald

    2005-01-01

    TiCl(4)-promoted multicomponent reactions involving N-tosyl imino ester, cyclic enol ether, and silane reagents in a single one-pot operation provide functionalized alpha-amino acids with multiple stereogenic centers in good to excellent yields. Cis/trans selectivities with optically active substituted dihydrofurans have been investigated. PMID:15624964

  13. Total synthesis of (±)-epithuriferic acid methyl ester via Diels-Alder reaction.

    PubMed

    Koprowski, Marek; Bałczewski, Piotr; Owsianik, Krzysztof; Różycka-Sokołowska, Ewa; Marciniak, Bernard

    2016-01-27

    In this paper, we have described the first total synthesis of (±)-epithuriferic acid methyl ester from non-natural sources, in four steps (20% overall yield). The key step involves the Diels-Alder reaction of isobenzofuran with methyl 3-(dimethoxyphosphoryl)acrylate which is controlled by "ortho" regio- and endo stereoselectivities due to the COOMe group. PMID:26750755

  14. Development of SSR Markers Linked to Low Hydrocyanic Acid Content in Sorghum-Sudan Grass Hybrid Based on BSA Method.

    PubMed

    Xiao-Xia, Yu; Zhi-Hua, Liu; Zhuo, Yu; Yue, Shi; Xiao-Yu, Li

    2016-01-01

    Sorghum-Sudan grass hybrid containing high hydrocyanic acid content can cause hydrocyanic acid poisoning to the livestock and limit the popularization of this forage crop. Molecular markers associated with low hydrocyanic acid content can speed up the process of identification of genotypes with low hydrocyanic acid content. In the present study, 11 polymorphic SSR primers were screened and used for bulked segregant analysis and single marker analysis. Three SSR markers Xtxp7230, Xtxp7375 and Bnlg667960 associated with low hydrocyanic acid content were rapidly identified by BSA. In single marker analysis, six markers Xtxp7230, Xtxp7375, Bnlg667960, Xtxp67-11, Xtxp295-7 and Xtxp12-9 were linked to low hydrocyanic acid content, which explained the proportion of phenotypic variation from 7.6 % to 41.2 %. The markers identified by BSA were also verified by single marker analysis. The three SSR marker bands were then cloned and sequenced for sequence homology analysis in NCBI. It is the first report on the development of molecular markers associated with low hydrocyanic acid content in sorghum- Sudan grass hybrid. These markers will be useful for genetic improvement of low hydrocyanic acid sorghum-Sudan grass hybrid by marker-assisted breeding. PMID:27001403

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

    SciTech Connect

    Menaa, Bouzid . E-mail: bouzidmenaa@noncry.kuicr.kyoto-u.ac.jp; Mizuno, Megumi; Takahashi, Masahide . E-mail: masahide@noncry.kuicr.kyoto-u.ac.jp; Tokuda, Yomei; Yoko, Toshinobu

    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.

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

    NASA Astrophysics Data System (ADS)

    Menaa, Bouzid; Mizuno, Megumi; Takahashi, Masahide; Tokuda, Yomei; Yoko, Toshinobu

    2006-02-01

    We investigated the water durability of the inorganic-organic hybrid tin-silico-phosphate glasses Me 2SiO-SnO-P 2O 5 (Me designs the organic methyl group) doped with organic acids (salicylic acid (SA), tartaric acid (TA), citric acid (CA) 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. 29Si magic angle spinning (MAS) NMR and 31P MAS NMR spectra, respectively, showed clearly a modification of the network in the host glass matrix of the Me 2SiO-SnO-P 2O 5 system. The polycondensation enhancement to form -P-O-Si-O-P- linkages (PSP) and the increase of the Q2 unit (two bridging oxygens per phosphorus atom) over the Q3 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.

  17. 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

  18. Geminal Brønsted Acid Ionic Liquids as Catalysts for the Mannich Reaction in Water

    PubMed Central

    He, Leqin; Qin, Shenjun; Chang, Tao; Sun, Yuzhuang; Zhao, Jiquan

    2014-01-01

    Quaternary ammonium geminal Brønsted acid ionic liquids (GBAILs) based on zwitterionic 1,2-bis[N-methyl-N-(3-sulfopropyl)-alkylammonium]ethane (where the carbon number of the alkyl chain is 4, 8, 10, 12, 14, 16, or 18) and p-toluenesulfonic acid monohydrate were synthesized. The catalytic ionic liquids were applied in three-component Mannich reactions with an aldehyde, ketone, and amine at 25 °C in water. The effects of the type and amount of catalyst and reaction time as well as the scope of the reaction were investigated. Results showed that GBAIL-C14 has excellent catalytic activity and fair reusability. The catalytic procedure was simple, and the catalyst could be recycled seven times via a simple separation process without noticeable decreases in catalytic activity. PMID:24837832

  19. Iterative reactions of transient boronic acids enable sequential C-C bond formation

    NASA Astrophysics Data System (ADS)

    Battilocchio, Claudio; Feist, Florian; Hafner, Andreas; Simon, Meike; Tran, Duc N.; Allwood, Daniel M.; Blakemore, David C.; Ley, Steven V.

    2016-04-01

    The ability to form multiple carbon-carbon bonds in a controlled sequence and thus rapidly build molecular complexity in an iterative fashion is an important goal in modern chemical synthesis. In recent times, transition-metal-catalysed coupling reactions have dominated in the development of C-C bond forming processes. A desire to reduce the reliance on precious metals and a need to obtain products with very low levels of metal impurities has brought a renewed focus on metal-free coupling processes. Here, we report the in situ preparation of reactive allylic and benzylic boronic acids, obtained by reacting flow-generated diazo compounds with boronic acids, and their application in controlled iterative C-C bond forming reactions is described. Thus far we have shown the formation of up to three C-C bonds in a sequence including the final trapping of a reactive boronic acid species with an aldehyde to generate a range of new chemical structures.

  20. Kinetic studies of Np(VI) reduction reactions with kojic acid and tropolone

    SciTech Connect

    Kim, W.

    1987-01-01

    To study the problems of potential migration of radionuclides from a nuclear waste repository, the Np(VI) reduction reactions with kojic acid and with tropolone were investigated at tracer level concentration of Np(VI). From results on the kinetic studies of these reactions, the NpO/sub 2//sup + +/ is reduced to the NpO/sub 2//sup +/ in a one-electron transfer process with no structural change of the dioxo neptunium species. The rates for both reactions are directly proportional to the total concentrations of Np(VI) ion and of oxidizing organic compounds: i.e., kojic acid or tropolone. However, the hydrogen ion dependence on the rate is inverse first-order for kojic acid and inverse second-order for tropolone. The Np(VI) reduction proceeds from the precursor complex via an activated complex and results in oxidation products from radicals formed in the rate-limiting step. The rate for the formation of Np(V) by kojic acid (k/sub 1/ = 6.06 +/- 0.30 sec/sup -1/) is faster than by tropolone (k/sub 1/ = 2.49 +/- 0.10 sec/sup -1/). The rate of reduction increases with the pK/sub a/ values (basicity) of the hydroxyl group in oxidizing organic compounds. The activation parameters for the Np(VI) reduction with kojic acid and tropolone have the same values within the uncertainties: i.e., ..delta..H/sup not equal to/ = 82.7 +/- 3.4 KJ/mol, ..delta..S/sup not equal to/ = 15 +/- 12 J/mol/deg for tropolone. Therefore, the Np(VI) reduction reaction occurs through the same mechanism in both reactions.

  1. 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 ...

  2. Adaptation of the interspersed repetitive sequence polymerase chain reaction to the isolation of mouse DNA probes from somatic cell hybrids on a hamster background

    SciTech Connect

    Simmler, M.C.; Cox, R.D.; Avner, P. )

    1991-07-01

    A strategy for the rapid isolation of DNA probes from radiation-fusion Chinese hamster cell hybrids containing overlapping portions of the murine X chromosome based on the interspersed repetitive sequence polymerase chain reaction (IRS-PCR) previously used with human somatic cell hybrids has been developed. This specific amplification of mouse DNA on a hamster background depends on the use of primers directed to the B2 short interspersed repeat element family and the R repeat, from the long interspersed repeat element family, L1. Two sets of amplification conditions, which gave specific amplification of mouse DNA from either a mouse X-monochromosomal hybrid or irradiation-fusion hybrids having reduced X content, were defined. The mouse X-only chromosome hybrid yielded approximately 20 discrete reproducible bands, while the irradiation-fusion hybrids yielded between 1 and 10 discrete products. Comparison of different irradiation-fusion hybrids has allowed the definition of both specific and shared products corresponding to different regions within the overlapping X-chromosome fragments present within these hybrids. Use of such hybrids and the IRS-PCR technique has allowed the isolation of probes corresponding to the central region of the mouse X chromosome that contains the X-inactivation center. The method should be widely applicable to the isolation of mouse DNA sequences from mouse hybrid cell lines on either human or Chinese hamster backgrounds.

  3. Effect of backbone chemistry on hybridization thermodynamics of oligonucleic acids: a coarse-grained molecular dynamics simulation study.

    PubMed

    Ghobadi, Ahmadreza F; Jayaraman, Arthi

    2016-02-17

    In this paper we study how varying oligonucleic acid backbone chemistry affects the hybridization/melting thermodynamics of oligonucleic acids. We first describe the coarse-grained (CG) model with tunable parameters that we developed to enable the study of both naturally occurring oligonucleic acids, such as DNA, and their chemically-modified analogues, such as peptide nucleic acids (PNAs) and locked nucleic acids (LNAs). The DNA melting curves obtained using such a CG model and molecular dynamics simulations in an implicit solvent and with explicit ions match with the melting curves obtained using the empirical nearest-neighbor models. We use these CG simulations to then elucidate the effect of backbone flexibility, charge, and nucleobase spacing along the backbone on the melting curves, potential energy and conformational entropy change upon hybridization and base-pair hydrogen bond residence time. We find that increasing backbone flexibility decreases duplex thermal stability and melting temperature mainly due to increased conformational entropy loss upon hybridization. Removing charges from the backbone enhances duplex thermal stability due to the elimination of electrostatic repulsion and as a result a larger energetic gain upon hybridization. Lastly, increasing nucleobase spacing decreases duplex thermal stability due to decreasing stacking interactions that are important for duplex stability. PMID:26777980

  4. Mesoporous Hybrid Shells of Carbonized Polyaniline/Mn2O3 as Non-Precious Efficient Oxygen Reduction Reaction Catalyst.

    PubMed

    Cao, Shiyi; Han, Na; Han, Jie; Hu, Yimin; Fan, Lei; Zhou, Chuanqiang; Guo, Rong

    2016-03-01

    Mesoporous hybrid shells of carbonized polyaniline (CPANI)/Mn2O3 with well-controlled diameter and high surface area have been synthesized through surface protected calcination processes. Originating from polystyrene template, PANI, MnO2, and SiO2 were sequentially loaded, followed by template removal and calcination, resulting in the desired CPANI/Mn2O3 hybrid shells. The introduction of SiO2 shell was established to play the determining role in maintaining the configuration during calcination process under high temperature. The CPANI/Mn2O3 hybrid shells showed outstanding electrocatalytic activity toward oxygen reduction reaction (ORR), with the onset potential at +0.974 V (versus RHE), the specific current at 60.8 mA/mg, and an overall quasi 4-electron transfer, which are comparable to those of the benchmark Pt/C. The remarkable ORR performance was attributed to the high specific surface area, the surface oxidation state of Mn, and composition-codependent behavior. PMID:26881985

  5. 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

  6. 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

  7. Sensitive detection of intracellular RNA of human telomerase by using graphene oxide as a carrier to deliver the assembly element of hybridization chain reaction.

    PubMed

    Shi, Zhilu; Zhang, Xiafei; Cheng, Rui; Li, Baoxin; Jin, Yan

    2016-04-25

    Since the level of human telomerase RNA (hTR) in tumor cells is higher than that in normal somatic cells, the quantitative assay of hTR is of significant importance in tumor diagnosis. Herein, graphene oxide (GO) was simultaneously exploited as a fluorescence quencher and a carrier of nucleic acid to successfully deliver two hairpin DNA probes of hybridization chain reaction (HCR) into the cancer cell for detecting telomerase RNA based on DNA nanoassembly of HCR. The sticky end of HCR probes could tightly absorb on the surface of GO, resulting in fluorescence quenching of the dye which was tagged at the sticky end of two hairpin probes. When faced with hTR, the fluorescence of DNA probes is subsequently recovered because hTR could trigger HCR to autonomous assembly of a DNA polymer which released from the GO and led to fluorescence recovery. Taking advantage of nucleic acid nanoassembly of HCR, this intracellular HCR strategy creates enormous signal amplification, and enables ultra-sensitive fluorescence imaging of hTR expression. By monitoring fluorescence change, human telomerase RNA could be specifically studied and this method can also be used for detecting single-base mutation. The GO-aided HCR strategy allowed us to sensitively detect hTR in a living cell, which holds great potential for analyzing other low-abundance biomolecules in living cells via HCR. PMID:27029779

  8. A hybrid Li-air battery with buckypaper air cathode and sulfuric acid electrolyte

    SciTech Connect

    Li, YF; Huang, K; Xing, YC

    2012-10-30

    We demonstrate a type of carbon nanotube based buckypaper cathode in a hybrid electrolyte Li-air battery (HyLAB) that showed outstanding discharging performances. The HyLAB has sulfuric acid as the catholyte and a large active electrode area (10 cm(2)). The active cathode layer was made from a buckypaper with 5 wt.% Pt supported on carbon nanotubes (Pt/CNTs) for oxygen reduction and evolution. A similar cathode was constructed with a catalyst of 5 wt.% Pt supported on carbon black (Pt/CB). It is demonstrated that sulfuric acid can achieve high discharging current densities while maintaining relatively high cell potentials. The cell with Pt/CNTs showed a much better performance than with Pt/CB at high current densities. The HyLAB with Pt/CNTs achieved a discharging capacity of 306 mAh/g and a cell voltage of 3.15 V at 0.2 mA/cm(2). The corresponding specific energy is 1067 Wh/kg based on the total weight of the sulfuric acid. Slow decrease in performance was observed, but it can be recovered by refilling the cell with new electrolyte after continuous discharging of more than 75 h. A charge-discharge experiment at 0.2 mA/cm(2) showed that the cell was rechargeable with a capacity of more than 300 mAh/g. (c) 2012 Elsevier Ltd. All rights reserved.

  9. 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.

  10. Identification of rifampin-resistant mycobacterium tuberculosis strains by hybridization, PCR, and ligase detaction reaction on oligonucleotide microchips.

    SciTech Connect

    Mikhailovich, V.; Lapa, S.; Gryadunov, D.; Sobolev, A.; Strizhkov, B.; Chernyh, N.; Skotnikova, O.; Irtuganova, O.; Moroz, A.; Litvinov, V.; Vladimirskii, M.; Perelman, M.; Chernousova, L.; Erokhin, V.; Mirzabekov, A.; Biochip Technology Center; Russian Academy of Sciences; Moscow Antituberculosis Center; Moscow Medical Academy; Russian Academy of Medical Sciences

    2001-07-01

    Three new molecular approaches were developed to identify drug-resistant strains of Mycobacterium tuberculosis using biochips with oligonucleotides immobilized in polyacrylamide gel pads. These approaches are significantly faster than traditional bacteriological methods. All three approaches -- hybridization, PCR, and ligase detection reaction -- were designed to analyze an 81-bp fragment of the gene rpoB encoding the {beta}-subunit of RNA polymerase, where most known mutations of rifampin resistance are located. The call set for hybridization analysis consisted of 42 immobilized oligonucleotides and enabled us to identify 30 mutant variants of the rpoB gene within 24 h. These variants are found in 95% of all mutants whose rifampin resistance is caused by mutations in the 81-bp fragment. Using the second approach, allele-specific on-chip PCR, it was possible to directly identify mutations in clinical samples within 1.5 h. The third approach, on-chip ligase detection reaction, was sensitive enough to reveal rifampin-resistant strains in a model mixture containing 1% of resistant and 99% of susceptible bacteria. This level of sensitivity is comparable to that from the determination of M. tuberculosis drug resistance by using standard bacteriological tests.

  11. Ultrasensitive and selective signal-on electrochemical DNA detection via exonuclease III catalysis and hybridization chain reaction amplification.

    PubMed

    Ren, Wang; Gao, Zhong Feng; Li, Nian Bing; Luo, Hong Qun

    2015-01-15

    This work reported a novel, ultrasensitive, and selective platform for electrochemical detection of DNA, employing an integration of exonuclease III (Exo-III) assisted target recycling and hybridization chain reaction (HCR) for the dual signal amplification strategy. The hairpin capture probe DNA (C-DNA) with an Exo-III 3' overhang end was self-assembled on a gold electrode. In the presence of target DNA (T-DNA), C-DNA hybridized with the T-DNA to form a duplex region, exposing its 5' complementary sequence (initiator). Exo-III was applied to selectively digest duplex region from its 3-hydroxyl termini until the duplex was fully consumed, leaving the remnant initiator. The intact T-DNA spontaneously dissociated from the structure and then initiated the next hybridization process as a result of catalysis of the Exo-III. HCR event was triggered by the initiator and two hairpin helper signal probes labeled with methylene blue, facilitating the polymerization of oligonucleotides into a long nicked dsDNA molecule. The numerous exposed remnant initiators can trigger more HCR events. Because of integration of dual signal amplification and the specific HCR process reaction, the resultant sensor showed a high sensitivity for the detection of the target DNA in a linear range from 1.0 fM to 1.0 nM, and a detection limit as low as 0.2 fM. The proposed dual signal amplification strategy provides a powerful tool for detecting different sequences of target DNA by changing the sequence of capture probe and signal probes, holding a great potential for early diagnosis in gene-related diseases. PMID:25083923

  12. Assessment of hybridization among wild and cultivated Vigna unguiculata subspecies revealed by arbitrarily primed polymerase chain reaction analysis

    PubMed Central

    Vijaykumar, Archana; Saini, Ajay; Jawali, Narendra

    2012-01-01

    Background and aims Intra-species hybridization and incompletely homogenized ribosomal RNA repeat units have earlier been reported in 21 accessions of Vigna unguiculata from six subspecies using internal transcribed spacer (ITS) and 5S intergenic spacer (IGS) analyses. However, the relationships among these accessions were not clear from these analyses. We therefore assessed intra-species hybridization in the same set of accessions. Methodology Arbitrarily primed polymerase chain reaction (AP-PCR) analysis was carried out using 12 primers. The PCR products were resolved on agarose gels and the DNA fragments were scored manually. Genetic relationships were inferred by TREECON software using unweighted paired group method with arithmetic averages (UPGMA) cluster analysis evaluated by bootstrapping and compared with previous analyses based on ITS and 5S IGS. Principal results A total of 202 (86 %) fragments were found to be polymorphic and used for generating a genetic distance matrix. Twenty-one V. unguiculata accessions were grouped into three main clusters. The cultivated subspecies (var. unguiculata) and most of its wild progenitors (var. spontanea) were placed in cluster I along with ssp. pubescens and ssp. stenophylla. Whereas var. spontanea were grouped with ssp. alba and ssp. tenuis accessions in cluster II, ssp. alba and ssp. baoulensis were included in cluster III. Close affinities of ssp. unguiculata, ssp. alba and ssp. tenuis suggested inter-subspecies hybridization. Conclusions Multi-locus AP-PCR analysis reveals that intra-species hybridization is prevalent among V. unguiculata subspecies and suggests that grouping of accessions from two different subspecies is not solely due to the similarity in the ITS and 5S IGS regions but also due to other regions of the genome. PMID:22619698

  13. Advanced design of valve-regulated lead-acid battery for hybrid electric vehicles

    NASA Astrophysics Data System (ADS)

    Lam, L. T.; Newnham, R. H.; Ozgun, H.; Fleming, F. A.

    A novel design of lead-acid battery has been developed for use in hybrid electric vehicles (HEVs). The battery has current take-offs at both ends of each of the positive and negative plates. This feature markedly reduces battery operating temperatures, improves battery capacity, and extends cycle-life under HEV duty. The battery also performs well under partial-state-of-charge (PSoC)/fast-charge, electric-vehicle operation. The improvements in performance are attributed to more uniform utilization of the plate active-materials. The battery, combined with an internal-combustion engine and a new type of supercapacitor, will be used to power an HEV, which is being designed and constructed by an Australian industry-government consortium.

  14. Heterogeneous Reactions of ClONO2, HCl, and HOCl on Liquid Sulfuric Acid Surfaces

    NASA Technical Reports Server (NTRS)

    Zhang, Renyi; Leu, Ming-Taun; Keyser, Leon F.

    1994-01-01

    The heterogeneous reactions of ClONO2 + H2O yields HNO3 + HOCl (1), ClONO2 + HCl yields C12 + HNO3 (2), and HOCl + HCl yields Cl2 + H2O (3) on liquid sulfuric acid surfaces have been studied using a fast flow reactor coupled to a quadrupole mass spectrometer. The main objectives of the study are to investigate: (a) the temperature dependence of these reactions at a fixed H2O partial pressure typical of the lower stratosphere (that is, by changing temperature at a constant water partial pressure, the H2SO4 content of the surfaces is also changed), (b) the relative importance or competition between reactions 1 and 2, and (c) the effect of HNO3 on the reaction probabilities due to the formation of a H2SO4/HNO3/H2O ternary system. The measurements show that all the reactions depend markedly on temperature at a fixed H2O partial pressure: they proceed efficiently at temperatures near 200 K and much slower at temperatures near 220 K. The reaction probability (gamma(sub 1)) for ClONO2 hydrolysis approaches 0.01 at temperatures below 200 K, whereas the values for gamma(sub 2) and gamma(sub 3) are on the order of a few tenths at 200 K. Although detailed mechanisms for these reactions are still unknown, the present data indicate that the competition between ClONO2 hydrolysis and ClONO2 reaction with HCl may depend on temperature (or H2SO4 Wt %): in the presence of gaseous HCl at stratospheric concentrations, reaction 2 is dominant at lower temperatures (less than 200 K), but reaction 1 becomes important at temperatures above 210 K. Furthermore, reaction probability measurements performed on the H2SO4/HNO3/ H2O ternary solutions do not exhibit noticeable deviation from those performed on the H2SO4/H2O binary system, suggesting little effect of HNO3 in sulfate aerosols on the ClONO2 and HOCl reactions with HCl. The results reveal that significant reductions in the chlorine-containing reservoir species (such as ClONO2 and HCl) can take place on stratospheric sulfate aerosols at high latitudes in winter and early spring, even at temperatures too warm for Polar Stratospheric Clouds (PSCs) to form or in regions where nucleation of PSCs is sparse. This is particularly true under elevated sulfuric acid loading, such as that after the eruption of Mt. Pinatubo. Comparisons between our results and those presently available have also been made.

  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

    ..., reaction products with 1-piperazineethanamine and tall-oil fatty acids. 721.10429 Section 721.10429... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10429 Fatty acids, C18-unsatd., dimers, reaction products with 1-piperazineethanamine and tall-oil fatty...

  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

    ..., reaction products with 1-piperazineethanamine and tall-oil fatty acids. 721.10429 Section 721.10429... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10429 Fatty acids, C18-unsatd., dimers, reaction products with 1-piperazineethanamine and tall-oil fatty...

  17. 40 CFR 721.6181 - Fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl ether...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6181 Fatty acid, reaction product with substituted oxirane, formaldehyde... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Fatty acid, reaction product...

  18. 40 CFR 721.10189 - Fatty acids, tall-oil, reaction products with (butoxymethyl) oxirane formaldehyde-phenol polymer...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... to reporting. (1) The chemical substance identified generically as fatty acids, tall-oil, reaction... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Fatty acids, tall-oil, reaction... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific...

  19. 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

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Fatty acids, tall-oil, reaction... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10188 Fatty acids, tall-oil, reaction products with 4-methyl-2-pentanone and aliphatic polyamine (generic)....

  20. 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

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Fatty acids, tall-oil, reaction... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10188 Fatty acids, tall-oil, reaction products with 4-methyl-2-pentanone and aliphatic polyamine (generic)....

  1. 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

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Fatty acids, tall-oil, reaction... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10188 Fatty acids, tall-oil, reaction products with 4-methyl-2-pentanone and aliphatic polyamine (generic)....

  2. 40 CFR 721.6181 - Fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl ether...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6181 Fatty acid, reaction product with substituted oxirane, formaldehyde... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Fatty acid, reaction product...

  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

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Fatty acids, tall-oil, reaction... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10188 Fatty acids, tall-oil, reaction products with 4-methyl-2-pentanone and aliphatic polyamine (generic)....

  4. 40 CFR 721.10189 - Fatty acids, tall-oil, reaction products with (butoxymethyl) oxirane formaldehyde-phenol polymer...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... to reporting. (1) The chemical substance identified generically as fatty acids, tall-oil, reaction... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Fatty acids, tall-oil, reaction... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific...

  5. 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

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Fatty acids, tall-oil, reaction... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10188 Fatty acids, tall-oil, reaction products with 4-methyl-2-pentanone and aliphatic polyamine (generic)....

  6. 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

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6181 Fatty acid, reaction product with substituted oxirane, formaldehyde... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Fatty acid, reaction product...

  7. Reaction Products of Unsaturated Polycarboxylic Acids and Sodium Hypophosphite for Improved Flame Resistance of Cotton-Containing Materials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reaction products of unsaturated polycarboxylic acids and sodium hypophosite were found to improve flame resistance of cellulosic materials as determined by the 45 degree flammability test for apparel textiles. The most effective product was that from the reaction of maleic acid with sodium hypopho...

  8. Quantitative study of solid-state acid-base reactions between polymorphs of flufenamic acid and magnesium oxide using X-ray powder diffraction.

    PubMed

    Chen, Xiaoming; Stowell, Joseph G; Morris, Kenneth R; Byrn, Stephen R

    2010-03-11

    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 degrees C. The disappearance of FFA and production of magnesium flufenamate were monitored by XRPD. It was observed that the reactions between FFA and MgO proceeded following the Jander equation. Form I of FFA is more reactive with MgO than Form III. Differential accessibility of reactive groups is hypothesized as one of the reasons that Form I is more reactive than Form III. It was noted that the reaction between FFA and MgO could be mitigated by adding another acidic excipient such as polyacrylic acid to prevent the acid-base reaction with FFA. The effectiveness of polyacrylic acid was impacted by the mixing order of the tertiary mixture. Mixing polyacrylic acid and MgO first provided the most significant protection. In conclusion, solid-state acid-base reactions could be investigated using XRPD. Different forms may have distinct reactivity. Acid-base reactions in the solid state could be mitigated through the addition of another "shielding" excipient. PMID:19906502

  9. 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.

  10. Reaction of single-standard DNA with hydroxyl radical generated by iron(II)-ethylenediaminetetraacetic acid

    SciTech Connect

    Prigodich, R.V. ); Martin, C.T. )

    1990-09-04

    This study demonstrates that the reaction of Fe(II)-EDTA and hydrogen peroxide with the single-stranded nucleic acids d(pT){sub 70} and a 29-base sequence containing a mixture of bases results in substantial damage which is not directly detected by gel electrophoresis. Cleavage of the DNA sugar backbone is enhanced significantly after the samples are incubated at 90{degree}C in the presence of piperidine. The latter reaction is used in traditional Maxam-Gilbert DNA sequencing to detect base damage, and the current results are consistent with reaction of the hydroxyl radical with the bases in single-stranded DNA (although reaction with sugar may also produce adducts that are uncleaved but labile to cleavage by piperidine). We the authors propose that hydroxyl radicals may react preferentially with the nucleic acid bases in ssDNA and that reaction of the sugars in dsDNA is dominant because the bases are sequestered within the double helix. These results have implications both for the study of single-stranded DNA binding protein binding sites and for the interpretation of experiments using the hydroxyl radical to probe DNA structure or to footprint double-stranded DNA binding protein binding sites.

  11. 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

  12. 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.

  13. Ferulic acid-carbazole hybrid compounds: Combination of cholinesterase inhibition, antioxidant and neuroprotection as multifunctional anti-Alzheimer agents.

    PubMed

    Fang, Lei; Chen, Mohao; Liu, Zhikun; Fang, Xubin; Gou, Shaohua; Chen, Li

    2016-02-15

    In order to search for novel multifunctional anti-Alzheimer agents, a series of ferulic acid-carbazole hybrid compounds were designed and synthesized. Ellman's assay revealed that the hybrid compounds showed moderate to potent inhibitory activity against the cholinesterases. Particularly, the AChE inhibition potency of compound 5k (IC50 1.9μM) was even 5-fold higher than that of galantamine. In addition, the target compounds showed pronounced antioxidant ability and neuroprotective property, especially against the ROS-induced toxicity. Notably, the neuroprotective effect of 5k was obviously superior to that of the mixture of ferulic acid and carbazole, indicating the therapeutic effect of the hybrid compound is better than the combination administration of the corresponding mixture. PMID:26795115

  14. 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.

  15. Chemically Activated Formation of Organic Acids in Reactions of the Criegee Intermediate with Aldehydes and Ketones

    SciTech Connect

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

    2013-08-08

    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 CQO 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 o CH3CHO o 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.

  16. 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

  17. AMINO ACID AVAILABILITY FROM ANIMAL PRODUCTS, BLENDED PRODUCTS AND PLANT PRODUCTS FOR HYBRID STRIPED BASS (MORONE CHRYSOPS X M. SAXATILIS).

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The refining of hybrid striped bass feed formulations has been progressing rapidly. There is still, however, limited information available regarding nutrient digestibility and amino acid availability from common feedstuffs. A pair of experiments was carried out to determine the protein digestibili...

  18. Cross-Dehydrogenative Coupling Reactions of sp3-Hybridized C-H Bonds

    NASA Astrophysics Data System (ADS)

    Yoo, Woo-Jin; Li, Chao-Jun

    New methodologies in cross-coupling reaction using C-H bonds as substrates is of great interest due to the challenges associated with C-H bond activation and the potential to streamline synthesis by the elimination of pre-activation of coupling reagents. In this chapter, recent developments in oxidative cross-coupling reactions will be presented with the focus on the functionalization of sp3 C-H bonds with other C-H bonds

  19. Kinetics of the reaction of adamantane and its derivatives with nitric acid

    SciTech Connect

    Klimochkin, Yu.N.; Moiseev, I.K.

    1988-08-10

    The reaction of adamantane compounds with nitric acid in methylene chloride is of first order with respect to the substrate, and its rate is proportional to the fifth power of the nitric acid concentration. A considerable kinetic isotope effect was found (4.4 /plus minus/ 0.3). The rate constants are linearly related to the solvolysis rate constants of the corresponding bromine derivatives and the Taft induction constants. A possible mechanism for oxynitration, including the removal of a hydride ion as controlling stage is proposed.

  20. Dynamic behavior of the bray-liebhafsky oscillatory reaction controlled by sulfuric acid and temperature

    NASA Astrophysics Data System (ADS)

    Pejić, N.; Vujković, M.; Maksimović, J.; Ivanović, A.; Anić, S.; Čupić, Ž.; Kolar-Anić, Lj.

    2011-12-01

    The non-periodic, periodic and chaotic regimes in the Bray-Liebhafsky (BL) oscillatory reaction observed in a continuously fed well stirred tank reactor (CSTR) under isothermal conditions at various inflow concentrations of the sulfuric acid were experimentally studied. In each series (at any fixed temperature), termination of oscillatory behavior via saddle loop infinite period bifurcation (SNIPER) as well as some kind of the Andronov-Hopf bifurcation is presented. In addition, it was found that an increase of temperature, in different series of experiments resulted in the shift of bifurcation point towards higher values of sulfuric acid concentration.

  1. Cytological and Deoxyribonucleic Acid-Deoxyribonucleic Acid Hybridization Studies on Lactobacillus Isolates from San Francisco Sourdough1

    PubMed Central

    Sriranganathan, N.; Seidler, Ramon J.; Sandine, W. E.; Elliker, P. R.

    1973-01-01

    Molecular taxonomic and electron microscopy studies were performed on four bacterial isolates obtained from different sources of San Francisco sourdough (SD). These bacteria were first isolated by Kline and Sugihara who tentatively described them as a previously unreported species of heterofermentative Lactobacillus; they suggested the name Lactobacillus sanfrancisco. The guanine plus cytosine base composition (%GC) of the deoxyribonucleic acid (DNA) ranged from 38 to 40%. The possible genetic relatedness of these SD isolates to five known species of Lactobacillus with comparable GC contents was assessed in the present work by means of DNA-DNA hybridization competition experiments. Little or no DNA homology was observed between the SD bacteria and the known species. The SD bacteria exhibited a high degree of homology (>88%) among themselves, suggesting that the four isolates were identical taxonomically. Also, the electron photomicrographs revealed structures similar to those of gram-positive bacilli. Accordingly, since these SD isolates have the characteristic phenotypic and morphological properties of the genus Lactobacillus and are not related genetically to any known species, the tentative characterization by the above workers of these isolates as a new species is substantiated. Images PMID:4633432

  2. 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.

  3. Origin of fatty acid synthesis - Thermodynamics and kinetics of reaction pathways

    NASA Technical Reports Server (NTRS)

    Weber, Arthur L.

    1991-01-01

    The primitiveness of contemporary fatty acid biosynthesis was evaluated by using the thermodynamics and kinetics of its component reactions to estimate the extent of its dependence on powerful and selective catalysis by enzymes. Since this analysis indicated that the modern pathway is not primitive because it requires sophisticated enzymatic catalysis, an alternative pathway of primitive fatty acid synthesis is proposed that uses glycolaldehyde as a substrate. In contrast to the modern pathway, this primitive pathway is not dependent on an exogenous source of phosphoanhydride energy. Furthermore, the chemical spontaneity of its reactions suggests that it could have been readily catalyzed by the rudimentary biocatalysts available at an early stage in the origin of life.

  4. [Experimental and kinetic modeling of acid/base and redox reactions over oxide catalysts]. Technical progress report

    SciTech Connect

    Not Available

    1993-07-01

    The research has involved the characterization of catalyst acidity, {sup 2}D NMR studies of Bronsted acid sites, and kinetic, calorimetric, and spectroscopic studies of methylamine synthesis and related reactions over acid catalysts. Approach of this work was to explore quantitative correlations between factors that control the generation, type, strength, and catalytic properties of acid sites on zeolite catalysts. Microcalorimetry, thermogravimetric analysis, IR spectroscopy, and NMR spectroscopy have provided information about the nature and strength of acid sites in zeolites. This was vital in understanding the catalytic cycles involved in methylamine synthesis and related reactions over zeolite catalysts.

  5. THE EFFECT OF ANOLYTE PRODUCT ACID CONCENTRATION ON HYBRID SULFUR CYCLE PERFORMANCE

    SciTech Connect

    Gorensek, M.; Summers, W.

    2010-03-24

    The Hybrid Sulfur (HyS) cycle (Fig. 1) is one of the simplest, all-fluids thermochemical cycles that has been devised for splitting water with a high-temperature nuclear or solar heat source. It was originally patented by Brecher and Wu in 1975 and extensively developed by Westinghouse in the late 1970s and early 1980s. As its name suggests, the only element used besides hydrogen and oxygen is sulfur, which is cycled between the +4 and +6 oxidation states. HyS comprises two steps. One is the thermochemical (>800 C) decomposition of sulfuric acid (H{sub 2}SO{sub 4}) to sulfur dioxide (SO{sub 2}), oxygen (O{sub 2}), and water. H{sub 2}SO{sub 4} = SO{sub 2} + 1/2 O{sub 2} + H{sub 2}O. The other is the SO{sub 2}-depolarized electrolysis of water to H{sub 2}SO{sub 4} and hydrogen (H{sub 2}), SO{sub 2} + 2 H{sub 2}O = H{sub 2}SO{sub 4} + H{sub 2}, E{sup o} = -0.156 V, explaining the 'hybrid' designation. These two steps taken together split water into H{sub 2} and O{sub 2} using heat and electricity. Researchers at the Savannah River National Laboratory (SRNL) and at the University of South Carolina (USC) have successfully demonstrated the use of proton exchange membrane (PEM) electrolyzers (Fig. 2) for the SO{sub 2}-depolarized electrolysis (sulfur oxidation) step, while Sandia National Laboratories (SNL) successfully demonstrated the high-temperature sulfuric acid decomposition (sulfur reduction) step using a bayonet-type reactor (Fig. 3). This latter work was performed as part of the Sulfur-Iodine (SI) cycle Integrated Laboratory Scale demonstration at General Atomics (GA). The combination of these two operations results in a simple process that will be more efficient and cost-effective for the massive production of hydrogen than alkaline electrolysis. Recent developments suggest that the use of PEMs other than Nafion will allow sulfuric acid to be produced at higher concentrations (>60 wt%), offering the possibility of net thermal efficiencies around 50% (HHV basis). The effect of operation at higher anolyte concentrations on the flowsheet, and on the net thermal efficiency for a nuclear-heated HyS process, is examined and quantified.

  6. Exploring the Hybridization Thermodynamics of Spherical Nucleic Acids to Tailor Probes for Diagnostic and Therapeutic Applications

    NASA Astrophysics Data System (ADS)

    Randeria, Pratik Shailesh

    Spherical nucleic acids (SNAs), three-dimensional nanoparticle conjugates composed of densely packed and highly oriented oligonucleotides around organic or inorganic nanoparticles, are an emergent class of nanostructures that show promise as single-entity agents for intracellular messenger RNA (mRNA) detection and gene regulation. SNAs exhibit superior biocompatibility and biological properties compared to linear oligonucleotides, enabling them to overcome many of the limitations of linear oligonucleotides for use in biomedical applications. However, the origins of these biologically attractive properties are not well understood. In this dissertation, the chemistry underlying one such property is studied in detail, and the findings are applied towards the rational design of more effective SNAs for diagnostic and therapeutic applications. Chapter 1 introduces the synthesis of SNAs, the unique properties that make them superior to linear nucleic acids for biomedicine, and previously studied applications of these structures. Chapter 2 focuses on quantitatively studying the impact of the chemical structure of the SNA on its ability to hybridize multiple complementary nucleic acids. This chapter lays the groundwork for understanding the factors that govern SNA hybridization thermodynamics and how to tailor SNAs to increase their binding affinity to target mRNA strands. Chapters 3 and 4 capitalize on this knowledge to engineer probes for intracellular mRNA detection and gene regulation applications. Chapter 3 reports the development of an SNA-based probe that can simultaneously report the expression level of two different mRNA transcripts in live cells and differentiate diseased cells from non-diseased cells. Chapter 4 investigates the use of topically-applied SNAs to down-regulate a critical mediator of impaired wound healing in diabetic mice to accelerate wound closure. This study represents the first topical therapeutic application of SNA nanotechnology to treat open wounds and lays the groundwork for developing SNA-based approaches for treating any skin-related disorder with a known genetic signature. Chapter 5 summarizes the key findings and conclusions and introduces future research directions. Taken together, this work demonstrates the important, and often surprising, role nanostructure plays in controlling biological properties and supports the continued development of SNAs as probes for molecular and medical biology.

  7. Proton transfer reactions in carbon nanotubes endohedrally functionalized with selected polar amino acid sidechains

    NASA Astrophysics Data System (ADS)

    Abi, T. G.; Taraphder, Srabani

    2012-09-01

    We use the empirical-valence-bond (EVB) theory to investigate intramolecular proton transfer reactions between a selected set of polar amino acid sidechains and hydroxyl groups suspended inside carbon nanotubes to model the effect of hydrophobic confinement on the energetics of proton transfer involving (i) translocation of an excess protonic charge (with protonated histidine sidechain as donor) and (ii) transformation of a neutral reactant state to a charge-separated product state (with sidechains of Asp, Glu, Ser and Thr as donor). In both the cases, confinement in hydrophobic medium is found to change the associated free energies compared to their respective values in the bulk solution phase. Presence of stable hydrogen bonding within the pore is found to have a significant effect on both free energies of reaction and activation and thus governs the thermodynamic and kinetic feasibilities of these intramolecular reactions in hydrophobic confinement.

  8. Secondary organic aerosol formation in the atmosphere via heterogeneous reaction of gaseous isoprene on acidic particles

    NASA Astrophysics Data System (ADS)

    Limbeck, Andreas; Kulmala, Markku; Puxbaum, Hans

    2003-10-01

    Water-soluble macromolecular substances with spectral properties of ``humic-like substances'' (HULIS) were recently found to form the major identified fraction of the organic aerosol at urban and rural sites in Europe. With primary sources identified so far (e.g., biomass combustion) it is not possible to explain the observed HULIS levels in Europe, therefore there is an ongoing search for other sources - which form HULIS in situ in the atmosphere. Here we show that secondary aerosol formation of atmospheric polymers occurs by heterogeneous reaction of isoprenoid or terpenoid emissions in the presence of a sulfuric acid aerosol catalyst. Competing oxidants such as ozone or the presence of humidity decreased the reaction yield, but the formation of humic-like substances was not disabled. Calculations indicate that the presented reaction pathway could be an additional source for HULIS in the continental aerosol.

  9. Impact of Lewis acids on Diels-Alder reaction reactivity: a conceptual density functional theory study.

    PubMed

    Xia, Yue; Yin, Dulin; Rong, Chunying; Xu, Qiong; Yin, Donghong; Liu, Shubin

    2008-10-01

    Density functional theory (DFT) and conceptual/chemical DFT studies are carried out in this work for the normal electron demand Diels-Alder reaction between isoprene and acrolein to compare chemical reactivity and regioselectivity of the reactants in the absence and presence of Lewis acid (LA) catalysts. A cyclic coplanar structure of acrolein-LA complex has been observed and the natural bond orbital analysis has been employed to interpret the interaction between acrolein and LAs. Reactivity indices from frontier molecular orbital energies are proved to be adequate and efficient to evaluate the catalytic property of LAs. Linear relationships have been discovered among the bond order, bond length, catalytic activation, and chemical reactivity for the systems concerned. The validity and applicability of maximum hardness principle, minimum polarizability principle, and minimum electrophilicity principle are examined and discussed in the prediction of the major regioselective isomer and the preferred reaction pathway for the reactions in the present study. PMID:18785697

  10. Hybrid pathwise sensitivity methods for discrete stochastic models of chemical reaction systems

    SciTech Connect

    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.

  11. Hybrid pathwise sensitivity methods for discrete stochastic models of chemical reaction systems

    NASA Astrophysics Data System (ADS)

    Wolf, Elizabeth Skubak; Anderson, David F.

    2015-01-01

    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.

  12. Hybrid method to resolve the neutrino mass hierarchy by supernova (anti)neutrino induced reactions

    NASA Astrophysics Data System (ADS)

    Vale, D.; Rauscher, T.; Paar, N.

    2016-02-01

    We introduce a hybrid method to determine the neutrino mass hierarchy by simultaneous measurements of responses of at least two detectors to antineutrino and neutrino fluxes from accretion and cooling phases of core-collapse supernovae. The (anti)neutrino-nucleus cross sections for 56Fe and 208Pb are calculated in the framework of the relativistic nuclear energy density functional and weak interaction Hamiltonian, while the cross sections for inelastic scattering on free protons p(bar nue,e+)n are obtained using heavy-baryon chiral perturbation theory. The modelling of (anti)neutrino fluxes emitted from a protoneutron star in a core-collapse supernova include collective and Mikheyev-Smirnov-Wolfenstein effects inside the exploding star. The particle emission rates from the elementary decay modes of the daughter nuclei are calculated for normal and inverted neutrino mass hierarchy. It is shown that simultaneous use of (anti)neutrino detectors with different target material allows to determine the neutrino mass hierarchy from the ratios of νe- and bar nue-induced particle emissions. This hybrid method favors neutrinos from the supernova cooling phase and the implementation of detectors with heavier target nuclei (208Pb) for the neutrino sector, while for antineutrinos the use of free protons in mineral oil or water is the appropriate choice.

  13. 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

  14. 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

  15. Nuclemeter: a reaction-diffusion based method for quantifying nucleic acids undergoing enzymatic amplification.

    PubMed

    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

  16. Resonance Rayleigh scattering study of the reaction of nucleic acids with thionine and its analytical application

    NASA Astrophysics Data System (ADS)

    Long, Xiufen; Bi, Shuping; Tao, Xiancong; Wang, Yongzhong; Zhao, Hong

    2004-01-01

    Resonance Rayleigh scattering (RRS) of the thionine (TH)-nucleic acids system and its analytical application have been studied. In pH 2.2 acidic buffer medium, some nucleic acids can react with TH to form TH-nucleic acids complex. This results in a great enhancement of RRS and the appearance of new RRS spectra. The RRS spectral characteristics of TH-ctDNA system, the affecting factors and the optimum conditions of the reaction have been investigated. The enhancement of the RRS signal is directly proportional to the concentration of nucleic acids in the range 0-10.0 μg/ml for calf thymus DNA and 0-15.0 μg/ml for yeast RNA, and its detection limits (3σ) are 3.5 ng/ml for calf thymus DNA and 4.9 ng/ml for yeast RNA, respectively. The method shows a wide linear range and high sensitivity, and was applied to the determination of trace amounts of nucleic acid in synthetic samples and practical samples with satisfactory results. The bind properties for the interactions of TH with ctDNA were investigated using a Scatchard plot based on the measurement of the enhanced RRS data at 340 nm, and the binding number and intrinsic binding constant are 4.9 and 2.6×10 5 mol/dm 3, respectively.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Intrinsically Labeled Fluorescent Oligonucleotide Probes on Quantum Dots for Transduction of Nucleic Acid Hybridization.

    PubMed

    Shahmuradyan, Anna; Krull, Ulrich J

    2016-03-15

    Quantum dots (QDs) have been widely used in chemical and biosensing due to their unique photoelectrical properties and are well suited as donors in fluorescence resonance energy transfer (FRET). Selective hybridization interactions of oligonucleotides on QDs have been determined by FRET. Typically, the QD-FRET constructs have made use of labeled targets or have implemented labeled sandwich format assays to introduce dyes in proximity to the QDs for the FRET process. The intention of this new work is to explore a method to incorporate the acceptor dye into the probe molecule. Thiazole orange (TO) derivatives are fluorescent intercalating dyes that have been used for detection of double-stranded nucleic acids. One such dye system has been reported in which single-stranded oligonucleotide probes were doubly labeled with adjacent thiazole orange derivatives. In the absence of the fully complementary (FC) oligonucleotide target, the dyes form an H-aggregate, which results in quenching of fluorescence emission due to excitonic interactions between the dyes. The hybridization of the FC target to the probe provides for dissociation of the aggregate as the dyes intercalate into the double stranded duplex, resulting in increased fluorescence. This work reports investigation of the dependence of the ratiometric signal on the type of linkage used to conjugate the dyes to the probe, the location of the dye along the length of the probe, and the distance between adjacent dye molecules. The limit of detection for 34mer and 90mer targets was found to be identical and was 10 nM (2 pmol), similar to analogous QD-FRET using labeled oligonucleotide target. The detection system could discriminate a one base pair mismatch (1BPM) target and was functional without substantial compromise of the signal in 75% serum. The 1BPM was found to reduce background signal, indicating that the structure of the mismatch affected the environment of the intercalating dyes. PMID:26866462

  2. In situ forming interpenetrating hydrogels of hyaluronic acid hybridized with iron oxide nanoparticles.

    PubMed

    Kheirabadi, Malihe; Shi, Liyang; Bagheri, Reza; Kabiri, Kourosh; Hilborn, Jöns; Ossipov, Dmitri A

    2015-11-01

    Four derivatives of hyaluronic acid (HA) bearing thiol (HA-SH), hydrazide (HA-hy), 2-dithiopyridyl (HA-SSPy), and aldehyde groups (HA-al) respectively were synthesized. Thiol and 2-dithiopyridyl as well as hydrazide and aldehyde make up two chemically orthogonal pairs of chemo-selective functionalities that allow in situ formation of interpenetrating (IPN) disulfide and hydrazone networks simultaneously upon the mixing of the above derivatives at once. The formation of IPN was demonstrated by comparing it with the formulations of the same total HA concentration but lacking one of the reactive components. The hydrogel composed of all four components was characterized by a larger elastic modulus than those of the control single networks (either disulfide or hydrazone) and the three component formulations gave the softest hydrogels. Moreover, a hydrazone cross-linkage was designed to contain a 1,2-diol fragment. This allowed us to partially disassemble one type of network in the IPN leaving another one unaffected. In particular, treatment of the IPN with either sodium periodate or dithiothreitol resulted in disassembly of the hydrazone and disulfide networks respectively and thus softening of the hydrogel. Contrarily, the single network hydrogels completely dissolved under the corresponding conditions. In corroboration with this, enzymatic degradation of the IPN by hyaluronidase was also substantially slower than the degradation of the single networks. In order to further improve the mechanical properties of the elaborated injectable IPN, it has been in situ hybridized with iron oxide nanoparticles (IONPs). The mesh size of the IPN was smaller than the size of the IONPs resulting in the retention of nanoparticles in the matrix under equilibrium swelling conditions. However, these nanoparticles were released upon enzymatic degradation suggesting their use as MRI tags for non-invasive tracking of the hydrogel material in vivo. Additionally, this injectable hybridized hydrogel with encapsulated IONPs can be used in hyperthermia cancer therapy. PMID:26247066

  3. C and N Hybrid Coordination Derived Co-C-N Complex as a Highly Efficient Electrocatalyst for Hydrogen Evolution Reaction.

    PubMed

    Wang, Zhong-Li; Hao, Xian-Feng; Jiang, Zheng; Sun, Xue-Ping; Xu, Dan; Wang, Jun; Zhong, Hai-Xia; Meng, Fan-Lu; Zhang, Xin-Bo

    2015-12-01

    Development of an efficient hydrogen evolution reaction (HER) catalyst composed of earth-abundant elements is scientifically and technologically important for the water splitting associated with the conversion and storage of renewable energy. Herein we report a new class of Co-C-N complex bonded carbon (only 0.22 at% Co) for HER with a self-supported and three-dimensional porous structure that shows an unexpected catalytic activity with low overpotential (212 mV at 100 mA cm(-2)) and long-term stability, better than that of most traditional-metal catalysts. Experimental observations in combination with density functional theory calculations reveal that C and N hybrid coordination optimizes the charge distribution and enhances the electron transfer, which synergistically promotes the proton adsorption and reduction kinetics. PMID:26555852

  4. Use of hybrid discrete cellular models for identification of macroscopic nutrient loss in reaction-diffusion models of tissues.

    PubMed

    Aristotelous, Andreas C; Haider, Mansoor A

    2014-08-01

    Macroscopic models accounting for cellular effects in natural or engineered tissues may involve unknown constitutive terms that are highly dependent on interactions at the scale of individual cells. Hybrid discrete models, which represent cells individually, were used to develop and apply techniques for modeling diffusive nutrient transport and cellular uptake to identify a nonlinear nutrient loss term in a macroscopic reaction-diffusion model of the system. Flexible and robust numerical methods were used, based on discontinuous Galerkin finite elements in space and a Crank-Nicolson temporal discretization. Scales were bridged via averaging operations over a complete set of subdomains yielding data for identification of a macroscopic nutrient loss term that was accurately captured via a fifth-order polynomial. Accuracy of the identified macroscopic model was demonstrated by direct, quantitative comparisons of the tissue and cellular scale models in terms of three error norms computed on a mesoscale mesh. PMID:24515852

  5. DNAzyme-based biosensor for Cu(2+) ion by combining hybridization chain reaction with fluorescence resonance energy transfer technique.

    PubMed

    Chen, Ying; Chen, Ling; Ou, Yidian; Wang, Zhenhua; Fu, Fengfu; Guo, Liangqia

    2016-08-01

    A novel signal amplification strategy based on Cu(2+)-dependent DNAzyme was developed for sensing Cu(2+) ion by combining hybridization chain reaction (HCR) with fluorescence resonance energy transfer (FRET) technique. In the presence of Cu(2+) ion, the substrate strands of Cu(2+)-dependent DNAzyme immobilized on magnetic beads were specifically cleaved and released. The released strands initiated the HCR process of hairpin H1 and H2 labeled with FAM as the donor and TAMRA as the acceptor, respectively. Long nicked dsDNA structures were self-assembled to bring the donor and the acceptor in close proximity, resulting in a FRET process. The relative ratio of fluorescent intensities of the acceptor and donor was used to quantitatively detect Cu(2+) ion with a limit of detection of 0.5nmolL(-1). This proposed biosensor was applied to detect Cu(2+) ion in tap water with satisfactory results. PMID:27216680

  6. Triggering hairpin-free chain-branching growth of fluorescent DNA dendrimers for nonlinear hybridization chain reaction.

    PubMed

    Xuan, Feng; Hsing, I-Ming

    2014-07-16

    We present a nonlinear hybridization chain reaction (HCR) system in which a trigger DNA initiates self-sustained assembly of quenched double-stranded substrates into fluorescent dendritic nanostructures. During the process, an increasing number of originally sequestered trigger sequences labeled with fluorescent reporters are freed up from quenched substrates, leading to chain-branching growth of the assembled DNA dendrimers and an exponential increase in the fluorescence intensity. The triggered assembly behavior was examined by PAGE analysis, and the morphologies of the grown dendrimers were verified by AFM imaging. The exponential kinetics of the fluorescence accumulation was also confirmed by time-dependent fluorescence spectroscopy. This method adopts a simple sequence design strategy, the concept of which could be adapted to program assembly systems with higher-order growth kinetics. PMID:24969438

  7. Ultrasensitive simultaneous detection of four biomarkers based on hybridization chain reaction and biotin-streptavidin signal amplification strategy.

    PubMed

    Zhu, Qiang; Chai, Yaqin; Zhuo, Ying; Yuan, Ruo

    2015-06-15

    A sandwich-type electrochemical immunosensor based on redox probe tags identification technology for ultrasensitive simultaneous detection of four antigens was proposed. In this project, well-distributed graphene/gold (GR-Au) hybrid film was acquired through one-step codeposition in an electrode surface and served as the base substrate for immobilizing capture antibodies (Ab1). Hybridization chain reaction (HCR) and biotin/streptavidin (B/SA), combining with gold magnetic nanoparticles were applied to increase the immobilization amount of signal tags in detection antibody (Ab2) bioconjugates. To verify this strategy, four representative biomarkers, a-fetoprotein (AFP), carcinoembryonic antigen (CEA), carbohydrate antigen (CA)125 and prostate special antigen (PSA), were used as model analytes. The resulting immunosensor could simultaneously detect four antigens in single-pass differential pulse voltammetry (DPV) scan, and exhibited obviously improved senstivity compared to previous similar immunosensors, displayed good linear relationships in the ranges from 0.2 to 800 pg/mL for AFP, 0.2 to 600 pg/mL for CEA, 0.2 to 1000 pg/mL for CA125, 0.2 to 800 pg/mL for PSA and with detection limits of 62, 48, 77 and 60 fg/mL, respectively. PMID:25562732

  8. Detection of Food Spoilage and Pathogenic Bacteria Based on Ligation Detection Reaction Coupled to Flow-Through Hybridization on Membranes

    PubMed Central

    Bhme, K.; Cremonesi, P.; Severgnini, M.; Villa, Toms G.; Fernndez-No, I. C.; Barros-Velzquez, 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

  9. 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

  10. Colorimetric detection of mercury ion based on unmodified gold nanoparticles and target-triggered hybridization chain reaction amplification.

    PubMed

    Wang, Qing; Yang, Xiaohan; Yang, Xiaohai; Liu, Pei; Wang, Kemin; Huang, Jin; Liu, Jianbo; Song, Chunxia; Wang, Jingjing

    2015-02-01

    A novel unmodified gold nanoparticles (AuNPs)-based colorimetric strategy for label-free, specific and sensitive mercury ion (Hg(2+)) detection was demonstrated by using thymine-Hg(2)(+)-thymine (T-Hg(2)(+)-T) recognition mechanism and hybridization chain reaction (HCR) amplification strategy. In this protocol, a structure-switching probe (H0) was designed to recognize Hg(2+) and then propagated a chain reaction of hybridization events between two other hairpin probes (H1 and H2). In the absence of Hg(2+), all hairpin probes could stably coexist in solution, the exposed sticky ends of hairpin probes were capable of stabilizing AuNPs. As a result, salt-induced AuNPs aggregation could be effectively prevented. In the presence of Hg(2+), thymine bases of H0 could specifically interact with Hg(2+) to form stable T-Hg(2)(+)-T complex. Consequently, the hairpin structure of H0 probe was changed. As H1/H2 probes were added, the HCR process could be triggered and nicked double-helixes were formed. Since it was difficult for the formed nicked double-helixes to inhibit salt-induced AuNPs aggregation, a red-to-blue color change was observed in the colloid solution as the salt concentration increased. With the elegant amplification effect of HCR, a detection limit of around 30 nM was achieved (S/N=3), which was about 1-2 orders of magnitudes lower than that of previous unmodified AuNPs-based colorimetric methods. By using the T-Hg(2)(+)-T recognition mechanism, high selectivity was also obtained. As an unmodified AuNPs-based colorimetric strategy, the system was simple in design, convenient in operation, and eliminated the requirements of separation processes, chemical modifications, and sophisticated instrumentations. PMID:25448931

  11. Colorimetric detection of mercury ion based on unmodified gold nanoparticles and target-triggered hybridization chain reaction amplification

    NASA Astrophysics Data System (ADS)

    Wang, Qing; Yang, Xiaohan; Yang, Xiaohai; Liu, Pei; Wang, Kemin; Huang, Jin; Liu, Jianbo; Song, Chunxia; Wang, Jingjing

    2015-02-01

    A novel unmodified gold nanoparticles (AuNPs)-based colorimetric strategy for label-free, specific and sensitive mercury ion (Hg2+) detection was demonstrated by using thymine-Hg2+-thymine (T-Hg2+-T) recognition mechanism and hybridization chain reaction (HCR) amplification strategy. In this protocol, a structure-switching probe (H0) was designed to recognize Hg2+ and then propagated a chain reaction of hybridization events between two other hairpin probes (H1 and H2). In the absence of Hg2+, all hairpin probes could stably coexist in solution, the exposed sticky ends of hairpin probes were capable of stabilizing AuNPs. As a result, salt-induced AuNPs aggregation could be effectively prevented. In the presence of Hg2+, thymine bases of H0 could specifically interact with Hg2+ to form stable T-Hg2+-T complex. Consequently, the hairpin structure of H0 probe was changed. As H1/H2 probes were added, the HCR process could be triggered and nicked double-helixes were formed. Since it was difficult for the formed nicked double-helixes to inhibit salt-induced AuNPs aggregation, a red-to-blue color change was observed in the colloid solution as the salt concentration increased. With the elegant amplification effect of HCR, a detection limit of around 30 nM was achieved (S/N = 3), which was about 1-2 orders of magnitudes lower than that of previous unmodified AuNPs-based colorimetric methods. By using the T-Hg2+-T recognition mechanism, high selectivity was also obtained. As an unmodified AuNPs-based colorimetric strategy, the system was simple in design, convenient in operation, and eliminated the requirements of separation processes, chemical modifications, and sophisticated instrumentations.

  12. Efficient Calculation of Enzyme Reaction Free Energy Profiles Using a Hybrid Differential Relaxation Algorithm: Application to Mycobacterial Zinc Hydrolases.

    PubMed

    Romero, Juan Manuel; Martin, Mariano; Ramirez, Claudia Lilián; Dumas, Victoria Gisel; Marti, Marcelo Adrián

    2015-01-01

    Determination of the free energy profile for an enzyme reaction mechanism is of primordial relevance, paving the way for our understanding of the enzyme's catalytic power at the molecular level. Although hybrid, mostly DFT-based, QM/MM methods have been extensively applied to this type of studies, achieving accurate and statistically converged results at a moderate computational cost is still an open challenge. Recently, we have shown that accurate results can be achieved in less computational time, combining Jarzynski's relationship with a hybrid differential relaxation algorithm (HyDRA), which allows partial relaxation of the solvent during the nonequilibrium steering of the reaction. In this work, we have applied this strategy to study two mycobacterial zinc hydrolases. Mycobacterium tuberculosis infections are still a worldwide problem and thus characterization and validation of new drug targets is an intense field of research. Among possible drug targets, recently two essential zinc hydrolases, MshB (Rv1170) and MA-amidase (Rv3717), have been proposed and structurally characterized. Although possible mechanisms have been proposed by analogy to the widely studied human Zn hydrolases, several key issues, particularly those related to Zn coordination sphere and its role in catalysis, remained unanswered. Our results show that mycobacterial Zn hydrolases share a basic two-step mechanism. First, the attacking water becomes deprotonated by the conserved base and establishes the new C-O bond leading to a tetrahedral intermediate. The intermediate requires moderate reorganization to allow for proton transfer to the amide N and C-N bond breaking to occur in the second step. Zn ion plays a key role in stabilizing the tetrahedral intermediate and balancing the negative charge of the substrate during hydroxide ion attack. Finally, comparative analysis of other Zn hydrolases points to a convergent mechanistic evolution. PMID:26415840

  13. Excellent anti-corrosive pretreatment layer on iron substrate based on three-dimensional porous phytic acid/silane hybrid

    NASA Astrophysics Data System (ADS)

    Gao, Xiang; Lu, Ke; Xu, Lei; Xu, Hua; Lu, Haifeng; Gao, Feng; Hou, Shifeng; Ma, Houyi

    2016-01-01

    A novel, highly effective and environmentally friendly film-forming material, phytic acid (PA)/silane (denoted as PAS) hybrid with a three-dimensional (3D) network structure, was prepared through a condensation reaction of PA with methyltrihydroxysilane generated from the hydrolysis of methyltriethoxysilane (MTES). Two kinds of PAS-based pretreatment layers, namely NaBrO3-free and NaBrO3-doped PAS layers, were fabricated on iron substrates using the dip-coating method. SEM and AFM observations showed that the as-fabricated PAS-based layers possessed a 3D porous microstructure at the nanoscale and a rough surface morphology. X-ray photoelectron spectroscopic (XPS) and attenuated total reflection infrared (ATR-IR) spectroscopic characterization demonstrated that the above PAS layers bound to the iron surface via the -P-O- bond. Moreover, analyses of steady-state polarization curves and electrochemical impedance spectroscopic (EIS) data indicated that the corrosion rates of the iron substrates decreased considerably in the presence of the two PAS-based pretreatment layers. In particular, the NaBrO3-dosed PAS layer displayed the better corrosion resistance ability as well as maintaining the original microstructure and surface morphology. The PAS-based pretreatment layers are expected to act as substitutes for chromate and phosphate conversion layers and will find widespread application in the surface pretreatment of iron and steel materials due to the advantages of being environmentally friendly, the rapid film-forming process, and, especially, the nanoporous microstructure and rough surface morphology.A novel, highly effective and environmentally friendly film-forming material, phytic acid (PA)/silane (denoted as PAS) hybrid with a three-dimensional (3D) network structure, was prepared through a condensation reaction of PA with methyltrihydroxysilane generated from the hydrolysis of methyltriethoxysilane (MTES). Two kinds of PAS-based pretreatment layers, namely NaBrO3-free and NaBrO3-doped PAS layers, were fabricated on iron substrates using the dip-coating method. SEM and AFM observations showed that the as-fabricated PAS-based layers possessed a 3D porous microstructure at the nanoscale and a rough surface morphology. X-ray photoelectron spectroscopic (XPS) and attenuated total reflection infrared (ATR-IR) spectroscopic characterization demonstrated that the above PAS layers bound to the iron surface via the -P-O- bond. Moreover, analyses of steady-state polarization curves and electrochemical impedance spectroscopic (EIS) data indicated that the corrosion rates of the iron substrates decreased considerably in the presence of the two PAS-based pretreatment layers. In particular, the NaBrO3-dosed PAS layer displayed the better corrosion resistance ability as well as maintaining the original microstructure and surface morphology. The PAS-based pretreatment layers are expected to act as substitutes for chromate and phosphate conversion layers and will find widespread application in the surface pretreatment of iron and steel materials due to the advantages of being environmentally friendly, the rapid film-forming process, and, especially, the nanoporous microstructure and rough surface morphology. Electronic supplementary information (ESI) available: Additional experimental data. See DOI: 10.1039/c5nr07366a

  14. Pulse radiolysis studies on reactions of ?-hydroxyalkyl radicals with nicotinamide and 6-methyl nicotinic acid

    NASA Astrophysics Data System (ADS)

    Dhiman, S. B.; Naik, D. B.

    2012-06-01

    Reactions of ?-hydroxyalkyl radicals derived from 2-propanol, ethanol and methanol with nicotinamide (NICAM) and 6-methyl nicotinic acid (6-MNA) were studied at various pHs using pulse radiolysis technique. It is found that ?-hydroxyalkyl radicals react with NICAM and 6-MNA at pHs when nitrogen is in the protonated state. In these reactions, radical adducts of NICAM/6-MNA with ?-hydroxyalkyl radicals are formed which have absorption maxima at about 340-350 nm which subsequently decay to give pyridinyl type of radicals of NICAM and 6-MNA having ?max at 410 nm. Rate constants for the reactions of (CH3)2Crad OH, CH3Crad HOH and rad CH2OH radicals with NICAM and 6-MNA were found to have linear dependence on reduction potentials of corresponding ?-hydroxyalkyl radicals. Adducts formed in the reactions of CH3Crad HOH and rad CH2OH radicals with both NICAM and 6-MNA decayed slowly compared to the decay of adduct formed in reactions with (CH3)2Crad OH radicals.

  15. Excellent anti-corrosive pretreatment layer on iron substrate based on three-dimensional porous phytic acid/silane hybrid.

    PubMed

    Gao, Xiang; Lu, Ke; Xu, Lei; Xu, Hua; Lu, Haifeng; Gao, Feng; Hou, Shifeng; Ma, Houyi

    2016-01-21

    A novel, highly effective and environmentally friendly film-forming material, phytic acid (PA)/silane (denoted as PAS) hybrid with a three-dimensional (3D) network structure, was prepared through a condensation reaction of PA with methyltrihydroxysilane generated from the hydrolysis of methyltriethoxysilane (MTES). Two kinds of PAS-based pretreatment layers, namely NaBrO3-free and NaBrO3-doped PAS layers, were fabricated on iron substrates using the dip-coating method. SEM and AFM observations showed that the as-fabricated PAS-based layers possessed a 3D porous microstructure at the nanoscale and a rough surface morphology. X-ray photoelectron spectroscopic (XPS) and attenuated total reflection infrared (ATR-IR) spectroscopic characterization demonstrated that the above PAS layers bound to the iron surface via the -P-O- bond. Moreover, analyses of steady-state polarization curves and electrochemical impedance spectroscopic (EIS) data indicated that the corrosion rates of the iron substrates decreased considerably in the presence of the two PAS-based pretreatment layers. In particular, the NaBrO3-dosed PAS layer displayed the better corrosion resistance ability as well as maintaining the original microstructure and surface morphology. The PAS-based pretreatment layers are expected to act as substitutes for chromate and phosphate conversion layers and will find widespread application in the surface pretreatment of iron and steel materials due to the advantages of being environmentally friendly, the rapid film-forming process, and, especially, the nanoporous microstructure and rough surface morphology. PMID:26689810

  16. Hybrid of chitin and humic acid as high performance sorbent for Ni(II)

    NASA Astrophysics Data System (ADS)

    Santosa, Sri Juari; Siswanta, Dwi; Kurniawan, Agusta; Rahmanto, Wasino H.

    2007-11-01

    Hybrid of humic acid (HA) and chitin has been synthesized and the hybrid material (chitin-HA) was then applied as sorbent to adsorb Ni(II). The HA was extracted from peat soil of Gambut District, South Kalimantan, Indonesia, according to the procedure recommended by IHSS (International Humic Substances Society). The chitin was isolated from crab shell waste of sea food restaurants through deproteination using NaOH 3.5% (w/v) and followed by removal of inorganic impurities using HCl 1 M. The synthesis of chitin-HA was performed by reacting gelatinous chitin solution in HCl 0.5 M and HA solution in NaOH 0.5 M. Parameters investigated in this work consists of effect of medium acidity on the sorption, sorption rate ( ks) and desorption rate ( kd) constants, Langmuir (monolayer) and Freundlich (multilayer) sorption capacities, and energy ( E) of sorption. The ks and kd were determined according to a kinetic model of first order sorption reaching equilibrium, monolayer sorption capacity ( b) and energy ( E) were determined according to the Langmuir isotherm model, and multilayer sorption capacity ( B) was determined based on the Freundlich isotherm model. Sorption of Ni(II) on both chitin and chitin-HA was maximum at pH 8.0. The kinetic expression resulted from the proposed kinetic model has been shown to be more applicable than the commonly known Lagergren equation obtained from the pseudo-first order sorption model. The application of the proposed model revealed that the presence of HA increased the ks from 0.018 min -1 for chitin to 0.031 min -1 for chitin-HA. As for ks, the value of b was also bigger in the presence of HA, i.e. 7.42 × 10 -5 mol/g for chitin and 9.93 × 10 -5 mol/g for the chitin-HA. Unlike ks and b, the value of E slightly decreased from 23.23 to 21.51 kJ/mol for the absence and presence of HA, respectively. It can also be deduced that the presence of HA on chitin contributed more to the additional layer of Ni(II) sorbed on sorbent. Without HA, B for chitin was only 6.17 times higher than b, while with the presence of HA, the enhancement of the sorption capacity from the multilayer ( B) to the monolayer ( b) was 19.40. The increase of ks, b, B, and the decrease of E would be very benefit in the real application of chitin-HA for the recovery of Ni(II) from aqueous samples.

  17. Structure of green pigment formed by the reaction of caffeic acid esters (or chlorogenic acid) with a primary amino compound.

    PubMed

    Yabuta, G; Koizumi, Y; Namiki, K; Hida, M; Namiki, M

    2001-10-01

    A marked greening observed in some foods such as sweet potato, burdock, and others during food processing was shown to be due to green pigment formation by the condensation reaction of two molecules of chlorogenic acid or caffeic acid ester with one molecule of a primary amino compound under aeration in alkaline solution. Reduction of the green pigment by ascorbic acid or NaBH4 gave a yellow product, which readily turn green and then blue in air. The reduced and acetylated product of the green pigment was identified to be a novel trihydroxy benzacridine derivative, and the yellowish ethanol solution of this product immediately turned green upon addition of butyl amine or diluted alkali. Therefore, the green pigment was assumed to be an oxidized quinone type product of trihydroxy benzacridine. This identification of the structure was supported by the correspondence of the measured absorption spectra with those calculated by the molecular orbital method. A possible charge transfer complex between products of different oxidation steps in green solution was proposed. PMID:11758899

  18. Designed synthesis of multi-walled carbon nanotubes@Cu@MoS2 hybrid as advanced electrocatalyst for highly efficient hydrogen evolution reaction

    NASA Astrophysics Data System (ADS)

    Li, Feng; Li, Jing; Lin, Xiaoqing; Li, Xinzhe; Fang, Yiyun; Jiao, Lixin; An, Xincai; Fu, Yan; Jin, Jun; Li, Rong

    2015-12-01

    Design and synthesis of non-precious-metal catalyst for efficient electrochemical transformation of water to molecular hydrogen in acid environments is of paramount importance in reducing energy losses during the water splitting process. Here, the hybrid material of MoS2-coated Cu loaded on the multi-walled carbon nanotubes (MWCNTs@Cu@MoS2) was synthesized using chemical process and hydrothermal method. It was found that the participation of MWCNTs and Cu nanoparticles not only improved the electrical conductivity of the catalyst, but also further enhanced the catalytic activity by synergistic effect with edge-exposed MoS2-coating. Electrochemical experiments demonstrated that the catalyst exhibited excellent hydrogen evolution reaction (HER) activity with large cathode currents (small overpotential of 184 mV for 10 mA cm-2 current density) and a Tafel slope as small as 62 mV per decade. Furthermore, it was discovered that the current density of this composite catalyst had a little decrease after the continual 1000 cycling, which showed the catalyst had a high stability in the recycling process. These findings confirmed that this catalyst was a useful and earth-abundant material for water splitting.

  19. Coupling hybridization chain reaction with catalytic hairpin assembly enables non-enzymatic and sensitive fluorescent detection of microRNA cancer biomarkers.

    PubMed

    Wei, Yulian; Zhou, Wenjiao; Li, Xin; Chai, Yaqin; Yuan, Ruo; Xiang, Yun

    2016-03-15

    The identification and quantification of sequence-specific microRNAs (miRNAs) plays an important role in early diagnosis of different diseases. In this work, by integrating two independent signal amplification approaches, hybridization chain reaction and catalytic hairpin assembly, we report an enzyme-free and dual amplified approach for highly sensitive detection of a human prostate cancer biomarker, miR-141. The presence of miR-141 triggers the self-assembly of two hairpin DNAs into dsDNA polymers, which co-localize two split segments of ssDNA into proximity. Subsequently, these co-localized ssDNA sequences further act as triggers to initiate catalytic assembly of two fluorescently quenched hairpin DNAs to form numerous dsDNA strands, resulting in the recovery of the fluorescent emissions and remarkably amplified signals for highly sensitive detection of miR-141 down to 0.3 fM. In addition, this method is also selective for the target miRNA against other control sequences. With the advantages of high sensitivity and nanomaterial/enzyme-free detection format, the developed method can be a general sensing platform for the detection of trace amounts of sequence-specific nucleic acid targets. PMID:26439017

  20. Cloning and characterization of the gene for L-amino acid oxidase in hybrid tilapia.

    PubMed

    Shen, Yubang; Fu, Gui Hong; Liu, Feng; Yue, Gen Hua

    2015-12-01

    Tilapia is the common name for a group of cichlid fishes. Identification of DNA markers significantly associated with important traits in candidate genes may speed up genetic improvement. L-Amino acid oxidase (LAO) plays a crucial role in the innate immune defences of animals. Previously, whether LAO variants were associated with economic traits had not been studied in fish. We characterized the cDNA sequence of the LAO gene of hybrid tilapia (Oreochromis spp.). Its ORF was 1536 bp, encoding a flavoenzyme of 511 amino acids. This gene consisted of seven exons and six introns. Its expression was detected in the intestine, blood, kidney, skin, liver. It was highly expressed in the intestine. After a challenge with a bacterial pathogen, Streptococcus agalactiae, its expression was up-regulated significantly in the liver, intestine and spleen (P < 0.05). We identified one SNP in the genomic sequence of the gene and found that this SNP was associated significantly with body length (P < 0.05), but not with resistance to S. agalactiae. The results of this study suggest that the LAO gene plays an important role in innate immune responses to the bacterial pathogen in tilapia. The investigation of relationship between polymorphism of LAO gene and disease resistance and growth in tilapia showed that one SNP was associated significantly with body length. Further experiments on whether SNPs in the LAO gene are associated with growth in tilapia and other populations could be useful in understanding more functions of the LAO gene. PMID:26546307

  1. Interphase fluorescence in situ hybridization and reverse transcription polymerase chain reaction as a diagnostic aid for synovial sarcoma.

    PubMed Central

    Shipley, J.; Crew, J.; Birdsall, S.; Gill, S.; Clark, J.; Fisher, C.; Kelsey, A.; Nojima, T.; Sonobe, H.; Cooper, C.; Gusterson, B.

    1996-01-01

    Identification of the t(X;18)(p11.2;q11.2) that is associated with a high proportion of synovial sarcoma can be a useful diagnostic aid. The translocation results in fusion of the SYT gene on chromosome 18 to either the SSX1 or the SSX2 gene, two homologous genes within Xp11.2. Two-color interphase fluorescence in situ hybridization and reverse transcription polymerase chain reaction were assessed as approaches to identify the rearrangement in well characterized cases. The presence of the translocation, and the specific chromosome X gene disrupted, were inferred from the configuration of signals from chromosome-specific centromere probes, paints, and markers flanking each gene in preparations of interphase nuclei. Rearrangement was found in two cell lines and eight of nine tumor samples, including analysis of five touch imprints. This was consistent with cytogenetic data in four cases and reverse transcription polymerase chain reaction analysis using primers known to amplify both SYT-SSX1 and SYT-SSX2 transcripts. The transcripts were distinguished by restriction with LspI and SmaI. Contrary to previous suggestions, there was no obvious correlation between histological subtype and involvement of the SSX1 or SSX2 gene. These approaches could also be applied to the identification of tumor-free margins and metastatic disease. Images Figure 1 Figure 3 PMID:8579118

  2. 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 10.0 U 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

  3. Conversion of isoamyl alcohol over acid catalysts: Reaction dependence on nature of active centers

    SciTech Connect

    Babu, G.P.; Murthy, R.S.; Krishnan, V.

    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.

  4. Iterative reactions of transient boronic acids enable sequential C-C bond formation.

    PubMed

    Battilocchio, Claudio; Feist, Florian; Hafner, Andreas; Simon, Meike; Tran, Duc N; Allwood, Daniel M; Blakemore, David C; Ley, Steven V

    2016-04-01

    The ability to form multiple carbon-carbon bonds in a controlled sequence and thus rapidly build molecular complexity in an iterative fashion is an important goal in modern chemical synthesis. In recent times, transition-metal-catalysed coupling reactions have dominated in the development of C-C bond forming processes. A desire to reduce the reliance on precious metals and a need to obtain products with very low levels of metal impurities has brought a renewed focus on metal-free coupling processes. Here, we report the in situ preparation of reactive allylic and benzylic boronic acids, obtained by reacting flow-generated diazo compounds with boronic acids, and their application in controlled iterative C-C bond forming reactions is described. Thus far we have shown the formation of up to three C-C bonds in a sequence including the final trapping of a reactive boronic acid species with an aldehyde to generate a range of new chemical structures. PMID:27001732

  5. Influence of salts, including amino acids, on the rate and outcome of the in-water prebiotic reactions

    NASA Astrophysics Data System (ADS)

    Kolb, Vera M.

    2013-09-01

    Most prebiotic reactions are hypothesized to have occurred in water. However, organic compounds in general are not water-soluble. This has created a great problem for prebiotic chemistry. However, it has been shown recently that many organic materials which are not soluble in water are still capable of reacting in water, often at faster rates than in the organic solvents. This has provided a new era in the study of the prebiotic reactions. Simulated prebiotic reactions are typically performed in water. However, presence of inorganic salts and the amino acids was ubiquitous in the aqueous media on the prebiotic Earth. We thus address the influence of common salts and selected water-soluble amino acids on the rate and outcome of selected prebiotic reactions in water. We focus on Diels-Alder (DA) reaction and multicomponent Passerini reaction (PR), as models for other prebiotic reactions. Some of the results came from our laboratory, and others are from the literature. DA reaction is influenced by salts and by selected water-soluble amino acids, but generally not to a large extent. The PR is also influenced by salts, but not dramatically. However, concentrations of salts and amino acids could have been extremely high in various local niches on the early Earth, and the influence of such concentrations on these prebiotic reactions awaits further study.

  6. Discrimination of bacteriophage infected cells using locked nucleic acid fluorescent in situ hybridization (LNA-FISH).

    PubMed

    Vilas Boas, Diana; Almeida, Carina; Sillankorva, Sanna; Nicolau, Ana; Azeredo, Joana; Azevedo, Nuno F

    2016-02-01

    Bacteriophage-host interaction studies in biofilm structures are still challenging due to the technical limitations of traditional methods. The aim of this study was to provide a direct fluorescence in situ hybridization (FISH) method based on locked nucleic acid (LNA) probes, which targets the phage replication phase, allowing the study of population dynamics during infection. Bacteriophages specific for two biofilm-forming bacteria, Pseudomonas aeruginosa and Acinetobacter, were selected. Four LNA probes were designed and optimized for phage-specific detection and for bacterial counterstaining. To validate the method, LNA-FISH counts were compared with the traditional plaque forming unit (PFU) technique. To visualize the progression of phage infection within a biofilm, colony-biofilms were formed and infected with bacteriophages. A good correlation (r = 0.707) was observed between LNA-FISH and PFU techniques. In biofilm structures, LNA-FISH provided a good discrimination of the infected cells and also allowed the assessment of the spatial distribution of infected and non-infected populations. PMID:26813295

  7. Mapping the regioisomeric distribution of fatty acids in triacylglycerols by hybrid mass spectrometry[S

    PubMed Central

    Nagy, Kornél; Sandoz, Laurence; Destaillats, Frédéric; Schafer, Olivier

    2013-01-01

    This study describes the use of hybrid mass spectrometry for the mapping, identification, and semi-quantitation of triacylglycerol regioisomers in fats and oils. The identification was performed based on the accurate mass and fragmentation pattern obtained by data-dependent fragmentation. Quantitation was based on the high-resolution ion chromatograms, and relative proportion of sn-1(3)/sn-2 regioisomers was calculated based on generalized fragmentation models and the relative intensities observed in the product ion spectra. The key performance features of the developed method are inter-batch mass accuracy < 1 ppm (n = 10); lower limit of detection (triggering threshold) 0.1 μg/ml (equivalent to 0.2 weight % in oil); lower limit of quantitation 0.2 μg/ml (equivalent to 0.4 weight % in oil); peak area precision 6.5% at 2 μg/ml concentration and 15% at 0.2 μM concentration; inter-batch precision of fragment intensities < 1% (n = 10) independent of the investigated concentration; and averaged accuracy using the generic calibration 3.8% in the 1–10 μg/ml range and varies between 1–23% depending on analytes. Inter-esterified fat, beef tallow, pork lard, and butter fat samples were used to show how well regioisomeric distribution of palmitic acid can be captured by this method. PMID:23093552

  8. Diagnosis of bacterial vaginosis by a new multiplex peptide nucleic acid fluorescence in situ hybridization method

    PubMed Central

    Machado, António; Castro, Joana; Cereija, Tatiana; Almeida, Carina

    2015-01-01

    Bacterial vaginosis (BV) is one of most common vaginal infections. However, its diagnosis by classical methods reveals low specificity. Our goal was to evaluate the accuracy diagnosis of 150 vaginal samples with research gold standard methods and our Peptide Nucleic Acid (PNA) probes by Fluorescence in situ Hybridization (FISH) methodology. Also, we described the first PNA-FISH methodology for BV diagnosis, which provides results in approximately 3 h. The results showed a sensitivity of 84.6% (95% confidence interval (CI), from 64.3 to 95.0%) and a specificity of 97.6% (95% CI [92.6–99.4%]), demonstrating the higher specificity of the PNA-FISH method and showing false positive results in BV diagnosis commonly obtained by the classical methods. This methodology combines the specificity of PNA probes for Lactobacillus species and G. vaginalis visualization and the calculation of the microscopic field by Nugent score, allowing a trustful evaluation of the bacteria present in vaginal microflora and avoiding the occurrence of misleading diagnostics. Therefore, the PNA-FISH methodology represents a valuable alternative for BV diagnosis. PMID:25737820

  9. Detection of Newcastle disease virus RNA by reverse transcription polymerase chain reaction using formalin-fixed, paraffin-embedded tissue and comparison with immunohistochemistry and in situ hybridization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The usefulness of reverse transcription polymerase chain reaction (RT-PCR) from formalin-fixed, paraffin-embedded (FFPE) tissues was examined and compared to the immunohistochemistry (IHC) and in situ hybridization (ISH) assays for detection of Newcastle disease virus (NDV). Spleen and lung tissues...

  10. MicroRNA detection based on analyte triggered nanoparticle localization on a tetrahedral DNA modified electrode followed by hybridization chain reaction dual amplification.

    PubMed

    Miao, Peng; Tang, Yuguo; Yin, Jian

    2015-11-01

    We have constructed an ultrasensitive method for microRNA detection based on analyte triggered nanoparticle localization and hybridization chain reaction dual amplification. The limit of detection is 2 aM. Furthermore, the applicability of this method for microRNA assay in real samples is demonstrated by the analysis of cell lysates. PMID:26376704

  11. The role of IgE recognition in allergic reactions to amoxicillin and clavulanic acid.

    PubMed

    Torres, M J; Montañez, M I; Ariza, A; Salas, M; Fernandez, T D; Barbero, N; Mayorga, C; Blanca, M

    2016-02-01

    Betalactam (BL) antibiotics are the drugs most frequently involved in IgE-mediated reactions. The culprit BL varies according to consumption patterns, with amoxicillin (AX) more prevalent in Southern Europe and penicillin V in Scandinavian countries. Nowadays, the combination of AX and clavulanic acid (CLV) is the most highly consumed BL containing medicine worldwide. Both BLs, AX and CLV, can independently be involved in reactions, which poses a diagnostic challenge. In patients with immediate allergic reactions to AX, two patterns of responses have been described, those responding to benzylpenicillin (cross-reactors) and those selective to AX. In addition, selective reactions to CLV account for around 30% of allergic reactions to the combination AX-CLV. These patterns of IgE recognition could be related to differences in the haptenation process, in the immunological response, or in the BL involved in the first sensitization. In this regard, patients with selective responses to CLV are generally younger than those allergic to AX or benzylpenicillin. So far, no evidence of cross-reactivity between CLV and other BLs has been reported. This shows the importance of an accurate diagnosis of CLV allergy, as patients with selective reactions to CLV could take other BLs including AX. Diagnosis can be performed in vivo and in vitro, although no immunoassay currently exists. Research regarding the CLV antigenic determinants and protein conjugates is essential to improve diagnosis. BLs need to covalently bind to a carrier protein to be immunogenic. The antigenic determinant of AX is the amoxicilloyl amide, but CLV leads to unstable structures, many of which are unknown. Moreover, the nature of the BL-protein conjugates plays an important role in IgE recognition. This review aims to summarize current knowledge on the immunochemistry, diagnostic approaches as well as chemical and proteomic studies for both AX and CLV. PMID:26662186

  12. Revisitation of the βCl-Elimination Reaction of d-Amino Acid Oxidase

    PubMed Central

    Ghisla, Sandro; Pollegioni, Loredano; Molla, Gianluca

    2011-01-01

    d-Amino acid oxidase (DAAO) from pig has been reported to catalyze the β-elimination of Cl− from βCl-d-alanine via abstraction of the substrate α-H as H+ (“carbanion mechanism”) (Walsh, C. T., Schonbrunn, A., and Abeles, R. H. (1971) J. Biol. Chem. 246, 6855–6866). In view of the fundamental mechanistic importance of this reaction and of the recent reinterpretation of the DAAO dehydrogenation step as occurring via a hydride mechanism, we reinvestigated the elimination reaction using yeast DAAO. That enzyme catalyzes the same reactions as the pig enzyme but with a much higher efficiency and a substantially different kinetic behavior. The reaction is initiated by a very rapid and fully reversible dehydrogenation step. This leads to an equilibrium (kon ≈ kreverse) between the complexes of oxidized enzyme-βCl-d-alanine and reduced enzyme-βCl-iminopyruvate. In the presence of O2 the latter complex can partition between an oxidative half-reaction and elimination of Cl−, which proceeds at a rate of ≈50 s−1. This step forms a complex between oxidized enzyme and enamine that is characterized by a charge transfer absorption (which describes its rates of formation and decay). A minimal scheme that lists relevant steps of the reductive and oxidative half-reactions and elimination pathways along with the estimate of the corresponding rate constants is presented. β-Elimination of Cl− is proposed to originate at the locus of the enzyme-βCl-iminopyruvate complex. A chemical mechanism that can account for elimination is discussed in detail. PMID:21949129

  13. The Modification of Cellulosic Surface with Fatty Acids via Plasma Mediated Reactions

    NASA Astrophysics Data System (ADS)

    Nada, Ahmed Ali Ahmed

    Much attention has been paid recently to understand the healing process made by the human body, in order to develop new approaches for promoting healing. The wound healing process includes four main phases, namely, hemostatic, inflammatory, proliferation, and remodeling, which take place successively. The human body can provide all the requirements of the healing process in normal wounds, unless there is a kind of deficiency of the skin function or massive fluid losses of vast wounds. Therefore, wound care of non-healing wounds has recently been the growing concern of many applications. The goal of this work is to explore the development of a new cellulose-based wound dressing composite that contain or release wound healing agents attained via dry textile chemical finishing techniques (thermal curing-plasma treatment). The synthesis of different wound healing agents derived from fatty acids and attached chemically to cellulose or even delivered through cyclodextrine modified cellulose are reported in this work. First, free fatty acids, which are obtained from commercial vegetable oils, were identified as wound healing agents. Many of these free acids are known to bind with and deactivate the proteases associated with inflammation at a wound site. Linoleic acid is extracted from commercial products of safflower seed oil while ricinoleic acid is obtained from castor oil. Conjugated linoleic acid was synthesized. Un-conjugated linoleic acid was used to prepare two derivatives namely linoleic azide and allylic ketone of linoleic acid. Different cellulose derivatives such as cellulose peroxide, iododeoxycellulose and cellulose diazonium salt in different degree of substitutions were synthesized in order to facilitate the free radical reaction with the fatty acid derivatives. New modified cellulosic products were synthesized by reacting the cellulosic and the linoleic acid derivatives via thermal or plasma technique and characterized by FT-IR ATR, the wettability test, etc. The cyto-compatiability of the new product was investigated using the cytotoxicity test to identify the cytotoxic potentials of the grafted samples. The highest yield was obtained in the thermal curing (at 140°C, 3 min, and a 20% solution of azide derivative -- 170°C, 3 min, and a 2.5% solution of allylic ketone derivatives) of the iododeoxycellulose fabrics with either linoleic azide or the allylic ketone derivative. Atmospheric plasma machines were used for this study such as NCAPS (dielectric barrier discharge plasma) and APJeT. APJet plasma machine was used in two different modes namely downstream and in-situ. Although, the plasma treatment uses a lower energy to achieve the chemical reactions between the two components, the APJet obtained good results in the in-situ mode (at 800 Watts/cm3 RF power, 45 sec. exposure time) while retaining sufficient tensile strength. In general samples treated with the allylic ketone of linoleic acid treated samples showed higher graft yield than the azide derivative, especially those treated via thermal curing. Moreover, they are more cytologically compatible than the plasma treated samples. In the course of producing a wound healing product that contains or releases fatty acids, allylic beta-CD was synthesized for first time as a textile finishing agent. Per(2, 3, 6- tri-O-allyl)-beta-CD was synthesized and characterized using spectral analysis. Cellulosic derivatives were treated with per(2, 3, 6- tri-O-allyl)-beta-CD via either pad-thermofixation technique or plasma treatment. Thermal treatment showed superior efficiency over plasma techniques to activate the vinyl groups and creating a self-assembled CD network chemically bonded with the cellulose derivatives (at 180°C, 3 min, and a 20 % solution of Per(2, 3, 6- tri- O-allyl)-beta-CD). APJeT machine (in-situ mode) succeeded only to activate cellulose/ allylic CD reaction, but however, it could not offer enough energy to stimulate vinyl-vinyl reactions. Oleic acid with its semi-linear chemical structure tends to include in the CD cavity faster and to higher levels, than the others after 4 hrs at 25°C. At higher temperatures the equilibrium of free and included oleic acid shifts and a remarkable decrease in the total inclusion was observed. However, ricinoleic acid anions showed very poor tendency for inclusion either with high temperature or at long time which may be attributed to its chemical structure, which is too large for the CD cavities. Also, un-conjugated linoleic acid anions showed higher inclusion than the conjugated ones. MMT assay was used to determine the cyto- compatibility for the newly modified samples. Generally speaking, the highest fixation yields the highest cyto-compatibility of the treated samples. Iododeoxycellulose samples in both thermal and plasma curing reported high cyto-compatibility either with allylic ketone or azide derivative of linoleic acid over the other cellulose derivatives. Pure extracted fatty acids or included ones showed high cyto-compatibility towards L929 mouse cell line.

  14. 40 CFR 721.6181 - Fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl ether...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... substituted oxirane, formaldehyde-phenol polymer glycidyl ether, substituted proplyamine and...-phenol polymer glycidyl ether, substituted proplyamine and polyethylenepolyamines (generic). (a) Chemical... as fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl...

  15. 40 CFR 721.6181 - Fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl ether...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... substituted oxirane, formaldehyde-phenol polymer glycidyl ether, substituted proplyamine and...-phenol polymer glycidyl ether, substituted proplyamine and polyethylenepolyamines (generic). (a) Chemical... as fatty acid, reaction product with substituted oxirane, formaldehyde-phenol polymer glycidyl...

  16. 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

  17. Single-molecule study on the temperature-sensitive reaction of F1-ATPase with a hybrid F1 carrying a single beta(E190D).

    PubMed

    Enoki, Sawako; Watanabe, Rikiya; Iino, Ryota; Noji, Hiroyuki

    2009-08-21

    F(1)-ATPase is a rotary molecular motor in which the gamma-subunit rotates against the alpha(3)beta(3) cylinder. The unitary gamma-rotation is a 120 degrees step comprising 80 and 40 degrees substeps, each of these initiated by ATP binding and ADP release and by ATP hydrolysis and inorganic phosphate release, respectively. In our previous study on gamma-rotation at low temperatures, a highly temperature-sensitive (TS) reaction step of F(1)-ATPase from thermophilic Bacillus PS3 was found below 9 degrees C as an intervening pause before the 80 degrees substep at the same angle for ATP binding and ADP release. However, it remains unclear as to which reaction step the TS reaction corresponds. In this study, we found that the mutant F(1)(beta E190D) from thermophilic Bacillus PS3 showed a clear pause of the TS reaction below 18 degrees C. In an attempt to identify the catalytic state of the TS reaction, the rotation of the hybrid F(1), carrying a single copy of beta E190D, was observed at 18 degrees C. The hybrid F(1) showed a pause of the TS reaction at the same angle as for the ATP binding of the incorporated beta E190D, although kinetic analysis revealed that the TS reaction is not the ATP binding step. These findings suggest that the TS reaction is a structural rearrangement of beta before or after ATP binding. PMID:19561076

  18. Maximum power output and load matching of a phosphoric acid fuel cell-thermoelectric generator hybrid system

    NASA Astrophysics Data System (ADS)

    Chen, Xiaohang; Wang, Yuan; Cai, Ling; Zhou, Yinghui

    2015-10-01

    Based on the current models of phosphoric acid fuel cells (PAFCs) and thermoelectric generators (TGs), a new hybrid system is proposed, in which the effects of multi-irreversibilities resulting from the activation, concentration, and ohmic overpotentials in the PAFC, Joule heat and heat leak in the TG, finite-rate heat transfer between the TG and the heat reservoirs, and heat leak from the PAFC to the environment are taken into account. Expressions for the power output and efficiency of the PAFC, TG, and hybrid system are analytically derived and directly used to discuss the performance characteristics of the hybrid system. The optimal relationship between the electric currents in the PAFC and TG is obtained. The maximum power output is numerically calculated. It is found that the maximum power output density of the hybrid system will increase about 150 Wm-2, compared with that of a single PAFC. The problem how to optimally match the load resistances of two subsystems is discussed. Some significant results for practical hybrid systems are obtained.

  19. Topological analysis of the electronic charge density in the ethene protonation reaction catalyzed by acidic zeolite.

    PubMed

    Zalazar, M Fernanda; Peruchena, Nélida M

    2007-08-16

    In the present work, the distribution of the electronic charge density in the ethene protonation reaction by a zeolite acid site is studied within the framework of the density functional theory and the atoms in molecules (AIM) theory. The key electronic effects such as topological distribution of the charge density involved in the reaction are presented and discussed. The results are obtained at B3LYP/6-31G(**) level theory. Attention is focused on topological parameters such as electron density, its Laplacian, kinetic energy density, potential energy density, and electronic energy density at the bond critical points (BCP) in all bonds involved in the interaction zone, in the reactants, pi-complex, transition state, and alkoxy product. In addition, the topological atomic properties are determined on the selected atoms in the course of the reaction (average electron population, N(Omega), atomic net charge, q(Omega), atomic energy, E(Omega), atomic volume, v(Omega), and first moment of the atomic charge distribution, M(Omega)) and their changes are analyzed exhaustively. The topological study clearly shows that the ethene interaction with the acid site of the zeolite cluster, T5-OH, in the ethene adsorbed, is dominated by a strong O-H...pi interaction with some degree of covalence. AIM analysis based on DFT calculation for the transition state (TS) shows that the hydrogen atom from the acid site in the zeolitic fragment is connected to the carbon atom by a covalent bond with some contribution of electrostatic interaction and to the oxygen atom by closed shell interaction with some contribution of covalent character. The C-O bond formed in the alkoxy product can be defined as a weaker shared interaction. Our results show that in the transition state, the dominant interactions are partially electrostatic and partially covalent in nature, in which the covalent contribution increases as the concentration and accumulation of the charge density along the bond path between the nuclei linked increases. PMID:17658733

  20. Megranate-like nanoreactor with multiple cores and an acidic mesoporous shell for a cascade reaction

    NASA Astrophysics Data System (ADS)

    Wang, Xue; Guan, Buyuan; He, Yapeng; An, Dong; Zhang, Ye; Cao, Yu; Li, Xiang; Liu, Yunling; Huo, Qisheng

    2015-02-01

    Megranate-like nanoparticles possess a unique structure that is composed of multiple cores and shells, which is different from simple yolk-shell nanoparticles. Megranate-like nanoparticles can combine the properties of each component and be used as nanoreactors. This study describes the preparation of bifunctional megranate-like nanoreactors, consisting of multiple metal cores and thiol modified mesoporous SiO2 shells. Different metal nanoparticles (Pd, Pt, Au) can be incorporated into the structure as cores, and the thiol group in the shells can be oxidized to acidic -SO3H. The megranate-like nanoparticles show good bifunctional catalytic properties and recyclability in a cascade catalytic reaction for the desired benzimidazole derivative. Moreover, the individual components of the megranate-like nanoparticles also show good catalytic activities in the hydrogenation reduction of nitro-aromatics and the deprotection reaction of benzaldehyde dimethyl acetal.Megranate-like nanoparticles possess a unique structure that is composed of multiple cores and shells, which is different from simple yolk-shell nanoparticles. Megranate-like nanoparticles can combine the properties of each component and be used as nanoreactors. This study describes the preparation of bifunctional megranate-like nanoreactors, consisting of multiple metal cores and thiol modified mesoporous SiO2 shells. Different metal nanoparticles (Pd, Pt, Au) can be incorporated into the structure as cores, and the thiol group in the shells can be oxidized to acidic -SO3H. The megranate-like nanoparticles show good bifunctional catalytic properties and recyclability in a cascade catalytic reaction for the desired benzimidazole derivative. Moreover, the individual components of the megranate-like nanoparticles also show good catalytic activities in the hydrogenation reduction of nitro-aromatics and the deprotection reaction of benzaldehyde dimethyl acetal. Electronic supplementary information (ESI) available: Figures show the TEM images, elemental mappings, NMR and HRMS results of the resultant samples. See DOI: 10.1039/c4nr06341d

  1. Application of pyridinium salts derived of barbituric acid in Kröhnke's reaction.

    PubMed

    Prelicz, D; Kasperek, L

    1975-01-01

    A series of pyridinium salts derived of barbituric acid (BAC) was obtained, as starting substances in Kröhnke's reaction. On the example of 3-(1',3'-dimethyl-5'-isopropylbarbituryl-5')-1-acetonylene-N-pyrifinium bromide it was stated that the corresponding nitron can be formed only when in positions 1 and 3 of barbituric ring are no hydrogen atoms able to enolization. 3-(1',3'-Dimethyl-5'-isopropylbarbituryl-5')-pyruvic aldehyde (XIII) was obtained by decomposition of nitron XII. PMID:1144211

  2. 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.

  3. Anti-Selective Aldol Reactions of Pentafluorosulfanylacetic Acid Esters with Aldehydes Mediated by Dicyclohexylchloroborane.

    PubMed

    Friese, Florian W; Dreier, Anna-Lena; Matsnev, Andrej V; Daniliuc, Constantin G; Thrasher, Joseph S; Haufe, Günter

    2016-03-01

    Aldol reactions of pentafluorosulfanyl (SF5)-substituted acetic acid esters with both aromatic and aliphatic aldehydes proceeded with excellent anti-diastereoselectivity and good to high yields using dicyclohexylchloroborane/triethylamine. This methodology enabled the synthesis of hitherto unknown α-SF5-β-hydroxy esters. Using a norephedrine-based auxiliary, high asymmetric induction was observed. The stereochemistry of products was assigned by NMR spectroscopy and proved by X-ray diffraction analysis. The intermediate enolate was identified as a highly unstable species. PMID:26909525

  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. Reactivity and reaction intermediates for acetic acid adsorbed on CeO2(111)

    SciTech Connect

    Calaza, Florencia; Chen, Tsung-Liang; Mullins, David R; Xu, Ye; Overbury, Steven {Steve} H

    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.

  6. Reactivity and reaction intermediates for acetic acid adsorbed on CeO2(111)

    DOE PAGESBeta

    Calaza, Florencia; Chen, Tsung-Liang; Mullins, David R; Xu, Ye; Overbury, Steven

    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.more » 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.« less

  7. Luminescent hybrid lanthanide sulfates and lanthanide sulfonate-carboxylates with 1,10-phenanthroline involving in-situ oxidation of 2-mercaptonbenzoic acid

    NASA Astrophysics Data System (ADS)

    Zhong, Jie-Cen; Wan, Fang; Sun, Yan-Qiong; Chen, Yi-Ping

    2015-01-01

    A series of lanthanide sulfates and lanthanide sulfonate-carboxylates, [Ln2(phen)2(SO4)3(H2O)2]n (I:Ln=Nd(1a), Sm(1b), Eu(1c), phen=1,10-phenanthroline) and [Ln(phen)(2-SBA)(BZA)]n (II: Ln=Sm(2a), Eu(2b), Dy(2c), 2-SBA=2-sulfobenzoate, BZA=benzoate) have been hydrothermally synthesized from lanthanide oxide, 2-mercaptonbenzoic acid with phen as auxiliary ligand and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra, TG analyses and luminescence spectroscopy. Interestingly, SO4 2 - anions in I came from the in situ deep oxidation of thiol groups of 2-mercaptonbenzoic acid while 2-sulfobenzoate and benzoate ligands in II from the middle oxidation and desulfuration reactions of 2-mercaptonbenzoic acid. Compounds I are organic-inorganic hybrid lanthanide sulfates, which have rare one-dimensional column-like structures. Complexes II are binuclear lanthanide sulfonate-carboxylates with 2-sulfobenzoate and benzoate as bridges and 1,10-phenanthroline as terminal. Photoluminescence studies reveal that complexes I and II exhibit strong lanthanide characteristic emission bands in the solid state at room temperature.

  8. Calibration and intercomparison of acetic acid measurements using proton transfer reaction mass spectrometry (PTR-MS)

    USGS Publications Warehouse

    Haase, K.B.; Keene, W.C.; Pszenny, A.A.P.; Mayne, H.R.; Talbot, R.W.; Sive, B.C.

    2012-01-01

    Acetic acid is one of the most abundant organic acids in the ambient atmosphere, with maximum mixing ratios reaching into the tens of parts per billion by volume (ppbv) range. The identities and associated magnitudes of the major sources and sinks for acetic acid are poorly characterized, due in part to the limitation in available measurement techniques. This paper demonstrates that Proton Transfer Reaction Mass Spectrometry (PTR-MS) can reliably quantify acetic acid vapor in ambient air. Three different PTR-MS configurations were calibrated at low ppbv mixing ratios using permeation tubes, which yielded calibration factors between 7.0 and 10.9 normalized counts per second per ppbv (ncps ppbv−1) at a drift tube field strength of 132 townsend (Td). Detection limits ranged from 0.06 to 0.32 ppbv with dwell times of 5 s. These calibration factors showed negligible humidity dependence. Using the experimentally determined calibration factors, PTR-MS measurements of acetic acid during the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) campaign were validated against results obtained using Mist Chambers coupled with Ion Chromatography (MC/IC). An orthogonal least squares linear regression of paired data yielded a slope of 1.14 ± 0.06 (2σ), an intercept of 0.049 ± 20 (2σ) ppbv, and an R2 of 0.78. The median mixing ratio of acetic acid on Appledore Island, ME during the ICARTT campaign was 0.530 ± 0.025 ppbv with a minimum of 0.075 ± 0.004 ppbv, and a maximum of 3.555 ± 0.171 ppbv.

  9. A Practical Guide for Predicting the Stereochemistry of Bifunctional Phosphoric Acid Catalyzed Reactions of Imines.

    PubMed

    Reid, Jolene P; Simón, Luis; Goodman, Jonathan M

    2016-05-17

    Chiral phosphoric acids have become powerful catalysts for the stereocontrolled synthesis of a diverse array of organic compounds. Since the initial report, the development of phosphoric acids as catalysts has been rapid, demonstrating the tremendous generality of this catalyst system and advancing the use of phosphoric acids to catalyze a broad range of asymmetric transformations ranging from Mannich reactions to hydrogenations through complementary modes of activation. These powerful applications have been developed without a clear mechanistic understanding of the reasons for the high level of stereocontrol. This Account describes investigations into the mechanism of the phosphoric acid catalyzed addition of nucleophiles to imines, focusing on binaphthol-based systems. In many cases, the hydroxyl phosphoric acid can form a hydrogen bond to the imine while the P═O interacts with the nucleophile. The single catalyst, therefore, activates both the electrophile and the nucleophile, while holding both in the chiral pocket created by the binaphthol and constrained by substituents at the 3 and 3' positions. Detailed geometric and energetic information about the transition states can be gained from calculations using ONIOM methods that combine the advantages of DFT with some of the speed of force fields. These high-level calculations give a quantitative account of the selectivity in many cases, but require substantial computational resources. A simple qualitative model is a useful complement to this complex quantitative model. We summarize our calculations into a working model that can readily be sketched by hand and used to work out the likely sense of selectivity for each reaction. The steric demands of the different parts of the reactants determine how they fit into the chiral cavity and which of the competing pathways is favored. The preferred pathway can be found by considering the size of the substituents on the nitrogen and carbon atoms of the imine electrophile, and the position of the nucleophilic site on the nucleophile in relation to the hydrogen-bond which holds it in the catalyst active site. We present a guide to defining the pathway in operation allowing the fast and easy prediction of the stereochemical outcome and provide an overview of the breadth of reactions that can be explained by these models including the latest examples. PMID:27128106

  10. Hybrid approaches for multiple-species stochastic reaction-diffusion models

    NASA Astrophysics Data System (ADS)

    Spill, Fabian; Guerrero, Pilar; Alarcon, Tomas; Maini, Philip K.; Byrne, Helen

    2015-10-01

    Reaction-diffusion models are used to describe systems in fields as diverse as physics, chemistry, ecology and biology. The fundamental quantities in such models are individual entities such as atoms and molecules, bacteria, cells or animals, which move and/or react in a stochastic manner. If the number of entities is large, accounting for each individual is inefficient, and often partial differential equation (PDE) models are used in which the stochastic behaviour of individuals is replaced by a description of the averaged, or mean behaviour of the system. In some situations the number of individuals is large in certain regions and small in others. In such cases, a stochastic model may be inefficient in one region, and a PDE model inaccurate in another. To overcome this problem, we develop a scheme which couples a stochastic reaction-diffusion system in one part of the domain with its mean field analogue, i.e. a discretised PDE model, in the other part of the domain. The interface in between the two domains occupies exactly one lattice site and is chosen such that the mean field description is still accurate there. In this way errors due to the flux between the domains are small. Our scheme can account for multiple dynamic interfaces separating multiple stochastic and deterministic domains, and the coupling between the domains conserves the total number of particles. The method preserves stochastic features such as extinction not observable in the mean field description, and is significantly faster to simulate on a computer than the pure stochastic model.

  11. 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.

  12. Nuclemeter: A Reaction-Diffusion Column for Quantifying Nucleic Acids Undergoing Enzymatic Amplification

    NASA Astrophysics Data System (ADS)

    Bau, Haim; Liu, Changchun; Killawala, Chitvan; Sadik, Mohamed; Mauk, Michael

    2014-11-01

    Real-time amplification and quantification of specific nucleic acid sequences plays a major role in many medical and biotechnological applications. In the case of infectious diseases, quantification of the pathogen-load in patient specimens is critical to assessing disease progression, effectiveness of drug therapy, and emergence of drug-resistance. Typically, nucleic acid quantification requires sophisticated and expensive instruments, such as real-time PCR machines, which are not appropriate for on-site use and for low resource settings. We describe a simple, low-cost, reactiondiffusion 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. We model the process with the Fisher Kolmogoroff Petrovskii Piscounoff (FKPP) Equation and compare theoretical predictions with experimental observations. The proposed method is suitable for nucleic acid quantification at the point of care, compatible with multiplexing and high-throughput processing, and can function instrument-free. C.L. was supported by NIH/NIAID K25AI099160; M.S. was supported by the Pennsylvania Ben Franklin Technology Development Authority; C.K. and H.B. were funded, in part, by NIH/NIAID 1R41AI104418-01A1.

  13. 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; Mosaddegh, Neda

    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.

  14. Aryl Ketone Synthesis via Tandem Orthoplatinated Triarylphosphite-Catalyzed Addition Reactions of Arylboronic Acids with Aldehydes Followed by Oxidation

    PubMed Central

    Liao, Yuan-Xi; Hu, Qiao-Sheng

    2010-01-01

    Tandem orthoplatinated triarylphosphite-catalyzed addition reactions of arylboronic acids with aldehydes followed by oxidation to yield aryl ketones is described. 3-Pentanone was identified as a suitable oxidant for the tandem aryl ketone formation reaction. By using microwave energy, aryl ketones were obtained in high yields with the catalyst loading as low as 0.01%. PMID:20849092

  15. Solvent-Free Conversion of Alpha-Naphthaldehyde to 1-Naphthoic Acid and 1-Naphthalenemethanol: Application of the Cannizzaro Reaction

    ERIC Educational Resources Information Center

    Esteb, John J.; Gligorich, Keith M.; O'Reilly, Stacy A.; Richter, Jeremy M.

    2004-01-01

    A mixture of potassium hydroxide and alpha-naphthaldehyde (1) are heated under solvent-free conditions to produce 1-naphthoic acid (2) and 1-naphthalenemethanol (3). The experiment offers several advantages over many existing exercises including the ease of reaction workup, shorter reaction time, relative environmental friendliness of the…

  16. Photo-induced coupling reactions of tetrazoles with carboxylic acids in aqueous solution: application in protein labelling.

    PubMed

    Zhao, Shan; Dai, Jianye; Hu, Mo; Liu, Chang; Meng, Rong; Liu, Xiaoyun; Wang, Chu; Luo, Tuoping

    2016-03-17

    The photo-induced reactions of diaryltetrazoles with carboxylic acids in aqueous solution were investigated. Besides measuring the apparent second-order rate constant and evaluating the functional group compatibility of these reactions, we further incorporated the tetrazoles into SAHA, leading to a new active-site-directed probe for labelling HDACs in both cell lysates and living cells. PMID:26953773

  17. 40 CFR 721.9220 - Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Reaction products of secondary alkyl... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9220 Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric...

  18. 40 CFR 721.9220 - Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Reaction products of secondary alkyl... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9220 Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric...

  19. 40 CFR 721.10136 - 2-Propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products with hexakis(alkoxyalkyl...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-hydroxyethyl ester, reaction products with hexakis(alkoxyalkyl)melamine (generic). 721.10136 Section 721.10136... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10136 2-Propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products with...

  20. 40 CFR 721.9400 - Reaction product of phenolic pentaerythritol tetraesters with fatty acid esters and oils, and...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Reaction product of phenolic... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9400 Reaction product of phenolic pentaerythritol tetraesters with fatty acid esters and oils, and...

  1. 40 CFR 721.10136 - 2-Propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products with hexakis(alkoxyalkyl...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-hydroxyethyl ester, reaction products with hexakis(alkoxyalkyl)melamine (generic). 721.10136 Section 721.10136... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10136 2-Propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products with...

  2. 40 CFR 721.10136 - 2-Propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products with hexakis(alkoxyalkyl...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-hydroxyethyl ester, reaction products with hexakis(alkoxyalkyl)melamine (generic). 721.10136 Section 721.10136... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10136 2-Propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products with...

  3. 40 CFR 721.9400 - Reaction product of phenolic pentaerythritol tetraesters with fatty acid esters and oils, and...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Reaction product of phenolic... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9400 Reaction product of phenolic pentaerythritol tetraesters with fatty acid esters and oils, and...

  4. 40 CFR 721.6477 - Alkyl polycarboxylic acids, esters with ethoxylated fatty alcohols, reaction products with maleic...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... with ethoxylated fatty alcohols, reaction products with maleic anhydride. 721.6477 Section 721.6477... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6477 Alkyl polycarboxylic acids, esters with ethoxylated fatty alcohols, reaction products with...

  5. 40 CFR 721.9220 - Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Reaction products of secondary alkyl... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9220 Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric...

  6. 40 CFR 721.10363 - Alkenoic acid, 2-methyl-, 2-oxiranylmethyl ester, reaction products with 4,4′ -methylenebis...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-oxiranylmethyl ester, reaction products with 4,4â² -methylenebis (cyclohexanamine) (generic). 721.10363 Section... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10363 Alkenoic acid, 2-methyl-, 2-oxiranylmethyl ester, reaction products with...

  7. 40 CFR 721.9220 - Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Reaction products of secondary alkyl... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9220 Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric...

  8. 40 CFR 721.6477 - Alkyl polycarboxylic acids, esters with ethoxylated fatty alcohols, reaction products with maleic...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... with ethoxylated fatty alcohols, reaction products with maleic anhydride. 721.6477 Section 721.6477... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6477 Alkyl polycarboxylic acids, esters with ethoxylated fatty alcohols, reaction products with...

  9. 40 CFR 721.9220 - Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Reaction products of secondary alkyl... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9220 Reaction products of secondary alkyl amines with a substituted benzenesulfonic acid and sulfuric...

  10. 40 CFR 721.9400 - Reaction product of phenolic pentaerythritol tetraesters with fatty acid esters and oils, and...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Reaction product of phenolic... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9400 Reaction product of phenolic pentaerythritol tetraesters with fatty acid esters and oils, and...

  11. 40 CFR 721.10136 - 2-Propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products with hexakis(alkoxyalkyl...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-hydroxyethyl ester, reaction products with hexakis(alkoxyalkyl)melamine (generic). 721.10136 Section 721.10136... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10136 2-Propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products with...

  12. 40 CFR 721.10363 - Alkenoic acid, 2-methyl-, 2-oxiranylmethyl ester, reaction products with 4,4′ -methylenebis...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-oxiranylmethyl ester, reaction products with 4,4â² -methylenebis (cyclohexanamine) (generic). 721.10363 Section... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10363 Alkenoic acid, 2-methyl-, 2-oxiranylmethyl ester, reaction products with...

  13. 40 CFR 721.10136 - 2-Propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products with hexakis(alkoxyalkyl...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-hydroxyethyl ester, reaction products with hexakis(alkoxyalkyl)melamine (generic). 721.10136 Section 721.10136... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10136 2-Propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products with...

  14. 40 CFR 721.9400 - Reaction product of phenolic pentaerythritol tetraesters with fatty acid esters and oils, and...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Reaction product of phenolic... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9400 Reaction product of phenolic pentaerythritol tetraesters with fatty acid esters and oils, and...

  15. 40 CFR 721.6477 - Alkyl polycarboxylic acids, esters with ethoxylated fatty alcohols, reaction products with maleic...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... with ethoxylated fatty alcohols, reaction products with maleic anhydride. 721.6477 Section 721.6477... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6477 Alkyl polycarboxylic acids, esters with ethoxylated fatty alcohols, reaction products with...

  16. 40 CFR 721.6477 - Alkyl polycarboxylic acids, esters with ethoxylated fatty alcohols, reaction products with maleic...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... with ethoxylated fatty alcohols, reaction products with maleic anhydride. 721.6477 Section 721.6477... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6477 Alkyl polycarboxylic acids, esters with ethoxylated fatty alcohols, reaction products with...

  17. 40 CFR 721.9400 - Reaction product of phenolic pentaerythritol tetraesters with fatty acid esters and oils, and...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Reaction product of phenolic... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9400 Reaction product of phenolic pentaerythritol tetraesters with fatty acid esters and oils, and...

  18. 40 CFR 721.10363 - Alkenoic acid, 2-methyl-, 2-oxiranylmethyl ester, reaction products with 4,4′ -methylenebis...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-oxiranylmethyl ester, reaction products with 4,4â² -methylenebis (cyclohexanamine) (generic). 721.10363 Section... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10363 Alkenoic acid, 2-methyl-, 2-oxiranylmethyl ester, reaction products with...

  19. 40 CFR 721.6477 - Alkyl polycarboxylic acids, esters with ethoxylated fatty alcohols, reaction products with maleic...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... with ethoxylated fatty alcohols, reaction products with maleic anhydride. 721.6477 Section 721.6477... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6477 Alkyl polycarboxylic acids, esters with ethoxylated fatty alcohols, reaction products with...

  20. The Effect of Incorporation of HNO(sub 3) Into Liquid Sulfuric Acid on Heterogeneous Reaction Probabilities

    NASA Technical Reports Server (NTRS)

    Zhang, R.; Leu, M-T.; Keyser, L.

    1994-01-01

    Using a fast-flow reactor coupled to a quadrupole mass spectrometer, the heterogeneous reactions of C1ONO2 + HCl and HOCl + HCl as well as hydrolysis of N2O5 and C1ONO2 were investigated on liquid sulfuric acid, with particular emphasis on the effect of incorporation of HNO3 on the reaction probabilities.