WorldWideScience

Sample records for bimolecular nucleophilic substitution

  1. Enabling nucleophilic substitution reactions of activated alkyl fluorides through hydrogen bonding.

    Science.gov (United States)

    Champagne, Pier Alexandre; Pomarole, Julien; Thérien, Marie-Ève; Benhassine, Yasmine; Beaulieu, Samuel; Legault, Claude Y; Paquin, Jean-François

    2013-05-03

    It was discovered that the presence of water as a cosolvent enables the reaction of activated alkyl fluorides for bimolecular nucleophilic substitution reactions. DFT calculations show that activation proceeds through stabilization of the transition structure by a stronger F···H2O interaction and diminishing C-F bond elongation, and not simple transition state electrostatic stabilization. Overall, the findings put forward a distinct strategy for C-F bond activation through H-bonding.

  2. Cation Radical Accelerated Nucleophilic Aromatic Substitution via Organic Photoredox Catalysis.

    Science.gov (United States)

    Tay, Nicholas E S; Nicewicz, David A

    2017-11-15

    Nucleophilic aromatic substitution (S N Ar) is a direct method for arene functionalization; however, it can be hampered by low reactivity of arene substrates and their availability. Herein we describe a cation radical-accelerated nucleophilic aromatic substitution using methoxy- and benzyloxy-groups as nucleofuges. In particular, lignin-derived aromatics containing guaiacol and veratrole motifs were competent substrates for functionalization. We also demonstrate an example of site-selective substitutive oxygenation with trifluoroethanol to afford the desired trifluoromethylaryl ether.

  3. Ionic Liquids: An Environmentally Friendly Media for Nucleophilic Substitution Reactions

    International Nuclear Information System (INIS)

    Jorapur, Yogesh R.; Chi, Dae Yoon

    2006-01-01

    Ionic liquids are alternative reaction media of increasing interest and are regarded as an eco-friendly alternatives, of potential use in place of the volatile organic solvents typically used in current chemical processing methods. They are emerging as the smart and excellent solvents, which are made of positive and negative ions that they are liquids near room temperature. The nucleophilic substitution reaction is one of the important method for inserting functional groups into a carbon skeleton. Many nucleophilic substitution reactions have been found with enhanced reactivity and selectivity in ionic liquid. In this review, some recent interesting results of nucleophilic substitution reactions such as hydroxylations, ether cleavages, carbon-X (X = carbon, oxygen, nitrogen, fluorine) bond forming reactions, and ring opening of epoxides in ionic liquids are discussed

  4. preparation and nucleophilic substitution of the 2,4,6

    African Journals Online (AJOL)

    Mgina

    Three methods for preparation of D-amino acids by nucleophilic substitution on derivatives of ... bioactivity of the peptide (Wenger 1985, ... Acetic acid (0.29 mL, 5 mmol) was added, and the mixture was further stirred for 5 h at rt under ... methanol/dichloromethane) to yield a white ... temperature, diluted with water, extracted.

  5. Nucleophilic Aromatic Substitution Between Halogenated Benzene Dopants and Nucleophiles in Atmospheric Pressure Photoionization.

    Science.gov (United States)

    Kauppila, Tiina J; Haack, Alexander; Kroll, Kai; Kersten, Hendrik; Benter, Thorsten

    2016-03-01

    In a preceding work with dopant assisted-atmospheric pressure photoionization (DA-APPI), an abundant ion at [M + 77](+) was observed in the spectra of pyridine and quinoline with chlorobenzene dopant. This contribution aims to reveal the identity and route of formation of this species, and to systematically investigate structurally related analytes and dopants. Compounds containing N-, O-, and S-lone pairs were investigated with APPI in the presence of fluoro-, chloro-, bromo-, and iodobenzene dopants. Computational calculations on a density functional theory (DFT) level were carried out to study the reaction mechanism for pyridine and the different halobenzenes. The experimental and computational results indicated that the [M + 77](+) ion was formed by nucleophilic aromatic ipso-substitution between the halobenzene radical cation and nucleophilic analytes. The reaction was most efficient for N-heteroaromatic compounds, and it was weakened by sterical effects and enhanced by resonance stabilization. The reaction was most efficient with chloro-, bromo-, and iodobenzenes, whereas with fluorobenzene the reaction was scarcely observed. The calculated Gibbs free energies for the reaction between pyridine and the halobenzenes were shown to increase in the order I < Br < Cl < F. The reaction was found endergonic for fluorobenzene due to the strong C-F bonding, and exergonic for the other halobenzenes. For fluoro- and chlorobenzenes the reaction was shown to proceed through an intermediate state corresponding to [M + dopant](+), which was highly stable for fluorobenzene. For the bulkier bromine and iodine, this intermediate did not exist, but the halogens were shown to detach already during the approach by the nucleophile.

  6. Experimental Determination of Activation Energy of Nucleophilic Aromatic Substitution on Porphyrins

    Science.gov (United States)

    Rizvi, Waqar; Khwaja, Emaad; Siddiqui, Saim; Bhupathiraju, N. V. S. Dinesh K.; Drain, Charles Michael

    2018-01-01

    A physical organic chemistry experiment is described for second-year college students. Students performed nucleophilic aromatic substitution (NAS) reactions on 5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin (TPPF[subscript 20]) using three different nucleophiles. Substitution occurs preferentially at the 4-position ("para")…

  7. General-base catalysed hydrolysis and nucleophilic substitution of activated amides in aqueous solutions

    NARCIS (Netherlands)

    Buurma, NJ; Blandamer, MJ; Engberts, JBFN; Buurma, Niklaas J.

    The reactivity of 1-benzoyl-3-phenyl-1,2,4-triazole (1a) was studied in the presence of a range of weak bases in aqueous solution. A change in mechanism is observed from general-base catalysed hydrolysis to nucleophilic substitution and general-base catalysed nucleophilic substitution. A slight

  8. Reactivity of polychlorinated biphenyls in nucleophilic and electrophilic substitutions

    Energy Technology Data Exchange (ETDEWEB)

    Gorbunova, Tatyana I., E-mail: gorbunova@ios.uran.ru [I. Ya. Postovskii Institute of Organic Synthesis, Ural Branch, Russian Academy of Sciences, Kovalevskoy St., 22, Ekaterinburg 620990 (Russian Federation); Subbotina, Julia O. [Ural Federal University named after the first President of Russia B.N. Yeltsin, Mira St., 19, Ekaterinburg 620002 (Russian Federation); Saloutin, Viktor I.; Chupakhin, Oleg N. [I. Ya. Postovskii Institute of Organic Synthesis, Ural Branch, Russian Academy of Sciences, Kovalevskoy St., 22, Ekaterinburg 620990 (Russian Federation)

    2014-08-15

    Graphical abstract: - Highlights: • Quantum chemical calculations were carried out for PCBs congeners. • Calculated descriptors were used to explain the PCBs reactivity in S{sub N} and S{sub E} substitutions. • Obtained data were used to estimate the PCBs reactivity in the S{sub N} reactions. • Calculated descriptors were insufficient to explain the PCBs reactivity in the S{sub E} reactions. • New neutralization methods of the large-capacity PCBs were discussed. - Abstract: To explain the chemical reactivity of polychlorinated biphenyls in nucleophilic (S{sub N}) and electrophilic (S{sub E}) substitutions, quantum chemical calculations were carried out at the B3LYP/6-31G(d) level of the Density Functional Theory in gas phase. Carbon atomic charges in biphenyl structure were calculated by the Atoms-in-Molecules method. Chemical hardness and global electrophilicity index parameters were determined for congeners. A comparison of calculated descriptors and experimental data for congener reactivity in the S{sub N} and S{sub E} reactions was made. It is shown that interactions in the S{sub N} mechanism are reactions of the hard acid–hard base type, these are the most effective in case of highly chlorinated substrates. To explain the congener reactivity in the S{sub E} reactions, correct descriptors were not established. The obtained results can be used to carry out chemical transformations of the polychlorinated biphenyls in order to prepare them for microbiological destruction or preservation.

  9. In situ nucleophilic substitutional growth of methylammonium lead iodide polycrystals.

    Energy Technology Data Exchange (ETDEWEB)

    Acik, Muge [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials and Nanoscience and Technology Division; Alam, Todd M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dept. of Organic Materials Science; Guo, Fangmin [Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS) and X-ray Science Division; Ren, Yang [Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS) and X-ray Science Division; Lee, Byeongdu [Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS) and X-ray Science Division; Rosenberg, Richard A. [Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS) and X-ray Science Division; Mitchell, JF [Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division; Kinaci, Alper [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials and Nanoscience and Technology Division; Chan, Maria [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials and Nanoscience and Technology Division; Darling, Seth B. [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials and Nanoscience and Technology Division; Univ. of Chicago, IL (United States). Inst. for Molecular Engineering

    2017-01-01

    Methylammonium lead iodide (MAPbIx) perovskites are organic-inorganic semiconductors that serve as the light-harvesting component of the photovoltaics, and are desirable with their long diffusion length yielding power conversion efficiencies of ≥22%. Conventional techniques grow perovskites by spin coating precursors on an oxide or a polymer substrate followed by annealing, however, use of high boiling point solvents and high temperatures hinder device stability and performance. Through a one-step, acid-catalyzed nucleophilic-substitutional crystal growth in polar protic solvents, we show evidence for the substrate- and annealing- free production of MAPbIx polycrystals that are metallic-lead-free with negligibly small amount of PbI2 precipitation (<10%). On the basis of this chemical composition, we have devised an in situ growth of highly air (upto ~1.5 months) and thermally-stable (≤300°C), tetragonal-phased, variable-sized polycrystals (~100 nm-10 μm) amendable for large-area deposition, and ultimately, large-scale manufacturing. This method is encouraging for stable optoelectronic devices, and leads to energy-efficient and low-cost processing.

  10. Energy landscapes of nucleophilic substitution reactions: a comparison of density functional theory and coupled cluster methods

    NARCIS (Netherlands)

    Swart, M.; Sola, M.; Bickelhaupt, F.M.

    2007-01-01

    We have carried out a detailed evaluation of the performance of all classes of density functional theory (DFT) for describing the potential energy surface (PES) of a wide range of nucleophilic substitution (S

  11. Synthesis and nucleophilic aromatic substitution of 3-fluoro-5-nitro-1-(pentafluorosulfanyl)benzene

    Czech Academy of Sciences Publication Activity Database

    Ajenjo, Javier; Greenhall, M.; Zarantonello, C.; Beier, Petr

    2016-01-01

    Roč. 12, Feb 3 (2016), s. 192-197 ISSN 1860-5397 EU Projects: European Commission(XE) 607787 - FLUOR21 Institutional support: RVO:61388963 Keywords : direct fluorination * fluorine * nucleophilic aromatic substitution * pentafluorosulfanyl group * vicarious nucleophilic substitution Subject RIV: CC - Organic Chemistry Impact factor: 2.337, year: 2016 http://www.beilstein-journals.org/bjoc/single/articleFullText.htm?publicId=1860-5397-12-21

  12. Continuous Flow Nucleophilic Aromatic Substitution with Dimethylamine Generated in Situ by Decomposition of DMF

    DEFF Research Database (Denmark)

    Petersen, Trine P; Larsen, Anders Foller; Ritzén, Andreas

    2013-01-01

    A safe, practical, and scalable continuous flow protocol for the in situ generation of dimethylamine from DMF followed by nucleophilic aromatic substitution of a broad range of aromatic and heteroaromatic halides is reported.......A safe, practical, and scalable continuous flow protocol for the in situ generation of dimethylamine from DMF followed by nucleophilic aromatic substitution of a broad range of aromatic and heteroaromatic halides is reported....

  13. Water promoted allylic nucleophilic substitution reactions of (E)-1,3 diphenylallyl acetate

    KAUST Repository

    Ghorpade, Seema Arun; Sawant, Dinesh N; Makki, Arwa; Sekar, N; Eppinger, Jö rg

    2017-01-01

    Transition metal free, water based, greener protocol for allylic alkylation, allylic amination, O-allylation of (E)-1,3-diphenylallyl acetate is described. The developed methodology is applicable for a wide range of nucleophiles furnishing excellent yields of corresponding products up to 87% under mild reaction conditions. A Distinct effect of water and base is explored for allylic nucleophilic substitution reactions of (E)-1,3-diphenylallyl acetate.

  14. Water promoted allylic nucleophilic substitution reactions of (E)-1,3 diphenylallyl acetate

    KAUST Repository

    Ghorpade, Seema Arun

    2017-11-30

    Transition metal free, water based, greener protocol for allylic alkylation, allylic amination, O-allylation of (E)-1,3-diphenylallyl acetate is described. The developed methodology is applicable for a wide range of nucleophiles furnishing excellent yields of corresponding products up to 87% under mild reaction conditions. A Distinct effect of water and base is explored for allylic nucleophilic substitution reactions of (E)-1,3-diphenylallyl acetate.

  15. Direct Amination of Nitro(pentafluorosulfanyl)benzenes through Vicarious Nucleophilic Substitution of Hydrogen

    Czech Academy of Sciences Publication Activity Database

    Pastýříková, Tereza; Iakobson, George; Vida, Norbert; Pohl, Radek; Beier, Petr

    -, č. 11 (2012), s. 2123-2126 ISSN 1434-193X R&D Projects: GA ČR GAP207/12/0072 Institutional research plan: CEZ:AV0Z40550506 Keywords : sulfur * amination * nucleophilic substitution * nitrogen heterocycles Subject RIV: CC - Organic Chemistry Impact factor: 3.344, year: 2012

  16. Hydroxylation of nitro-(pentafluorosulfanyl)benzenes via vicarious nucleophilic substitution of hydrogen

    Czech Academy of Sciences Publication Activity Database

    Beier, Petr; Pastýříková, Tereza

    2011-01-01

    Roč. 52, č. 34 (2011), s. 4392-4394 ISSN 0040-4039 R&D Projects: GA ČR GAP207/11/0344 Institutional research plan: CEZ:AV0Z40550506 Keywords : pentafluorosulfanyl group * vicarious nucleophilic substitution * hydroxylation Subject RIV: CC - Organic Chemistry Impact factor: 2.683, year: 2011

  17. Oxidative nucleophilic substitution of hydrogen in nitro(pentafluorosulfanyl)benzenes with alkyl Grignard and lithium reagents

    Czech Academy of Sciences Publication Activity Database

    Vida, Norbert; Beier, Petr

    2012-01-01

    Roč. 143, SI (2012), s. 130-134 ISSN 0022-1139 R&D Projects: GA ČR GAP207/12/0072 Institutional support: RVO:61388963 Keywords : pentafluorosulfanyl group * nucleophilic aromatic substitutions * oxidations Subject RIV: CC - Organic Chemistry Impact factor: 1.939, year: 2012

  18. Synthesis of a Fluorescent Acridone Using a Grignard Addition, Oxidation, and Nucleophilic Aromatic Substitution Reaction Sequence

    Science.gov (United States)

    Goodrich, Samuel; Patel, Miloni; Woydziak, Zachary R.

    2015-01-01

    A three-pot synthesis oriented for an undergraduate organic chemistry laboratory was developed to construct a fluorescent acridone molecule. This laboratory experiment utilizes Grignard addition to an aldehyde, alcohol oxidation, and iterative nucleophilic aromatic substitution steps to produce the final product. Each of the intermediates and the…

  19. Utilizing the σ-complex stability for quantifying reactivity in nucleophilic substitution of aromatic fluorides

    Directory of Open Access Journals (Sweden)

    Magnus Liljenberg

    2013-04-01

    Full Text Available A computational approach using density functional theory to compute the energies of the possible σ-complex reaction intermediates, the “σ-complex approach”, has been shown to be very useful in predicting regioselectivity, in electrophilic as well as nucleophilic aromatic substitution. In this article we give a short overview of the background for these investigations and the general requirements for predictive reactivity models for the pharmaceutical industry. We also present new results regarding the reaction rates and regioselectivities in nucleophilic substitution of fluorinated aromatics. They were rationalized by investigating linear correlations between experimental rate constants (k from the literature with a theoretical quantity, which we call the sigma stability (SS. The SS is the energy change associated with formation of the intermediate σ-complex by attachment of the nucleophile to the aromatic ring. The correlations, which include both neutral (NH3 and anionic (MeO− nucleophiles are quite satisfactory (r = 0.93 to r = 0.99, and SS is thus useful for quantifying both global (substrate and local (positional reactivity in SNAr reactions of fluorinated aromatic substrates. A mechanistic analysis shows that the geometric structure of the σ-complex resembles the rate-limiting transition state and that this provides a rationale for the observed correlations between the SS and the reaction rate.

  20. Development of selective colorimetric probes for hydrogen sulfide based on nucleophilic aromatic substitution.

    Science.gov (United States)

    Montoya, Leticia A; Pearce, Taylor F; Hansen, Ryan J; Zakharov, Lev N; Pluth, Michael D

    2013-07-05

    Hydrogen sulfide is an important biological signaling molecule and an important environmental target for detection. A major challenge in developing H2S detection methods is separating the often similar reactivity of thiols and other nucleophiles from H2S. To address this need, the nucleophilic aromatic substitution (SNAr) reaction of H2S with electron-poor aromatic electrophiles was developed as a strategy to separate H2S and thiol reactivity. Treatment of aqueous solutions of nitrobenzofurazan (7-nitro-1,2,3-benzoxadiazole, NBD) thioethers with H2S resulted in thiol extrusion and formation of nitrobenzofurazan thiol (λmax = 534 nm). This reactivity allows for unwanted thioether products to be converted to the desired nitrobenzofurazan thiol upon reaction with H2S. The scope of the reaction was investigated using a Hammett linear free energy relationship study, and the determined ρ = +0.34 is consistent with the proposed SN2Ar reaction mechanism. The efficacy of the developed probes was demonstrated in buffer and in serum with associated submicromolar detection limits as low as 190 nM (buffer) and 380 nM (serum). Furthermore, the sigmoidal response of nitrobenzofurazan electrophiles with H2S can be fit to accurately quantify H2S. The developed detection strategy offers a manifold for H2S detection that we foresee being applied in various future applications.

  1. Reduced Reactivity of Amines against Nucleophilic Substitution via Reversible Reaction with Carbon Dioxide

    Directory of Open Access Journals (Sweden)

    Fiaz S. Mohammed

    2015-12-01

    Full Text Available The reversible reaction of carbon dioxide (CO2 with primary amines to form alkyl-ammonium carbamates is demonstrated in this work to reduce amine reactivity against nucleophilic substitution reactions with benzophenone and phenyl isocyanate. The reversible formation of carbamates has been recently exploited for a number of unique applications including the formation of reversible ionic liquids and surfactants. For these applications, reduced reactivity of the carbamate is imperative, particularly for applications in reactions and separations. In this work, carbamate formation resulted in a 67% reduction in yield for urea synthesis and 55% reduction for imine synthesis. Furthermore, the amine reactivity can be recovered upon reversal of the carbamate reaction, demonstrating reversibility. The strong nucleophilic properties of amines often require protection/de-protection schemes during bi-functional coupling reactions. This typically requires three separate reaction steps to achieve a single transformation, which is the motivation behind Green Chemistry Principle #8: Reduce Derivatives. Based upon the reduced reactivity, there is potential to employ the reversible carbamate reaction as an alternative method for amine protection in the presence of competing reactions. For the context of this work, CO2 is envisioned as a green protecting agent to suppress formation of n-phenyl benzophenoneimine and various n-phenyl–n-alky ureas.

  2. Nucleophilic Substitution Reactions of N-Methyl α-Bromoacetanilides with Benzylamines in Dimethyl Sulfoxide

    International Nuclear Information System (INIS)

    Adhikary, Keshab Kumar; Lee, Hai Whang

    2011-01-01

    Kinetic studies of the reactions of N-methyl-Y-α-bromoacetanilides with substituted X-benzylamines have been carried out in dimethyl sulfoxide at 25.0 .deg. C. The Hammett plots for substituent X variations in the nucleophiles (log k N vs σ X ) are slightly biphasic concave upwards/downwards, while the Bronsted plots (log k N vs pK a ) are biphasic concave downwards with breakpoints at X = H. The Hammett plots for substituent Y variations in the substrates (log k N vs σ Y ) are biphasic concave upwards/downwards with breakpoints at Y = H. The cross-interaction constant ρ XY values are all negative: ρ XY = -0.32 for X = Y = electron-donating: -0.22 for X = electron-withdrawing and Y = electron-donating: -1.80 for X = electron-donating and Y = electronwithdrawing: -1.43 for X = Y = electron-withdrawing substituents. Deuterated kinetic isotope effects are primary normal (k H /k D > 1) for Y = electron-donating, while secondary inverse (k H /k D < 1) for Y = electronwithdrawing substituent. The proposed mechanisms of the benzylaminolyses of N-methyl-Y-α-bromoacetanilides are a concerted mechanism with a five membered ring TS involving hydrogen bonding between hydrogen (deuterium) atom in N-H(D) and oxygen atom in C = O for Y = electron-donating, while a concerted mechanism with an enolate-like TS in which the nucleophile attacks the α-carbon for Y = electronwithdrawing substituents

  3. Citrus Peel Additives for One-Pot Triazole Formation by Decarboxylation, Nucleophilic Substitution, and Azide-Alkyne Cycloaddition Reactions

    Science.gov (United States)

    Mendes, Desiree E.; Schoffstall, Allen M.

    2011-01-01

    This undergraduate organic laboratory experiment consists of three different reactions occurring in the same flask: a cycloaddition reaction, preceded by decarboxylation and nucleophilic substitution reactions. The decarboxylation and cycloaddition reactions occur using identical Cu(I) catalyst and conditions. Orange, lemon, and other citrus fruit…

  4. Theoretical studies of the nucleophilic substitution of halides and amine at a sulfonyl center.

    Science.gov (United States)

    Sung, Dae Dong; Kim, Tae Joon; Lee, Ikchoon

    2009-06-25

    Gas-phase nucleophilic substitution reactions, F(-) + CH(3)SO(2)F, Cl(-) + CH(3)SO(2)Cl, Cl(-) + CH(3)SO(2)F, and NH(3) + CH(3)SO(2)Cl, have been investigated at the B3LYP/6-311+G** and MP2/6-31+G* levels of theory. A very shallow well for the reaction intermediate in a triple-well potential energy surface (PES) was observed for the identity fluoride exchange, but double well PESs were obtained for the other three reactions with three different PES profiles. NBO analyses of the transition states showed substantial charge transfer interactions in all cases which provided a much larger amount of stabilization energy compared with the corresponding species at the carbon center of methyl halides. This difference is primarily caused by the strong electropositive nature of the sulfur center. The F-S-F axial linkage in the distorted TBP type intermediate in the identity fluoride exchange reaction exhibited a weak three-center, four-electron omega-bonding, which is considered to provide stability of the intermediate. All the reactant (RC) and product complexes (PC) have Cs symmetry. The symmetry plane bisects angles HCH (of methyl group), OSO (of sulfonyl group), and HNH (of ammonia). Vicinal charge transfer interactions between the two out-of-plane C-H, S-O, and N-H bonds provide extra stabilization to the ion-dipole complexes together with H-bond formation of in-plane H atom with the nucleophile and/or leaving group.

  5. Homologation chemistry with nucleophilic α-substituted organometallic reagents: chemocontrol, new concepts and (solved) challenges.

    Science.gov (United States)

    Castoldi, Laura; Monticelli, Serena; Senatore, Raffaele; Ielo, Laura; Pace, Vittorio

    2018-05-31

    The transfer of a reactive nucleophilic CH2X unit into a preformed bond enables the introduction of a fragment featuring the exact and desired degree of functionalization through a single synthetic operation. The instability of metallated α-organometallic species often poses serious questions regarding the practicability of using this conceptually intuitive and simple approach for forming C-C or C-heteroatom bonds. A deep understanding of processes regulating the formation of these nucleophiles is a precious source of inspiration not only for successfully applying theoretically feasible transformations (i.e. determining how to employ a given reagent), but also for designing new reactions which ultimately lead to the introduction of molecular complexity via short experimental sequences.

  6. Direct no-carrier-added 18F-labelling of arenes via nucleophilic substitution on aryl(2-thienyl)iodonium salts

    International Nuclear Information System (INIS)

    Ross, T.L.

    2006-01-01

    For in vivo imaging of molecular processes via positron emission tomography (PET) radiotracers of high specific activity are demanded. In case of the most commonly used positron emitter fluorine-18, this is only achievable with no-carrier-added [ 18 F]fluoride, which implies nucleophilic methods of 18 F-substitution. Whereas electron deficient aromatic groups can be labelled in one step using no-carrier-added [ 18 F]fluoride, electron rich 18 F-labelled aromatic molecules are only available by multi-step radiosyntheses or carrier-added electrophilic reactions. Here, diaryliodonium salts represent an alternative, since they have been proven as potent precursor for a direct nucleophilic 18 F-introduction into aromatic molecules. Furthermore, as known from non-radioactive studies, the highly electron rich 2-thienyliodonium leaving group leads to a high regioselectivity in nucleophilic substitution reactions. Consequently, a direct nucleophilic no-carrier-added 18 F-labelling of electron rich arenes via aryl(2-thienyl)iodonium precursors was developed in this work. The applicability of direct nucleophilic 18 F-labelling was examined in a systematic study on eighteen aryl(2-thienyl)iodonium salts. As electron rich precursors the ortho-, meta- and para-methoxyphenyl(2-thienyl)iodonium bromides, iodides, tosylates and triflates were synthesised. In addition, para-substituted (R=BnO, CH 3 , H, Cl, Br, I) aryl(2-thienyl)iodonium bromides were prepared as precursors with a systematically varying electron density. As first approach, the general reaction conditions of the nucleophilic 18 F-substitution procedure were optimised. The best conditions for direct nucleophilic no-carrier-added 18 F-labelling via aryl(2-thienyl)iodonium salts were found with dimethylformamide as solvent, a reaction temperature of 130±3 C and 25 mmol/l as concentration of the precursor. (orig.)

  7. Direct no-carrier-added {sup 18}F-labelling of arenes via nucleophilic substitution on aryl(2-thienyl)iodonium salts

    Energy Technology Data Exchange (ETDEWEB)

    Ross, T L

    2006-01-15

    For in vivo imaging of molecular processes via positron emission tomography (PET) radiotracers of high specific activity are demanded. In case of the most commonly used positron emitter fluorine-18, this is only achievable with no-carrier-added [{sup 18}F]fluoride, which implies nucleophilic methods of {sup 18}F-substitution. Whereas electron deficient aromatic groups can be labelled in one step using no-carrier-added [{sup 18}F]fluoride, electron rich {sup 18}F-labelled aromatic molecules are only available by multi-step radiosyntheses or carrier-added electrophilic reactions. Here, diaryliodonium salts represent an alternative, since they have been proven as potent precursor for a direct nucleophilic {sup 18}F-introduction into aromatic molecules. Furthermore, as known from non-radioactive studies, the highly electron rich 2-thienyliodonium leaving group leads to a high regioselectivity in nucleophilic substitution reactions. Consequently, a direct nucleophilic no-carrier-added {sup 18}F-labelling of electron rich arenes via aryl(2-thienyl)iodonium precursors was developed in this work. The applicability of direct nucleophilic {sup 18}F-labelling was examined in a systematic study on eighteen aryl(2-thienyl)iodonium salts. As electron rich precursors the ortho-, meta- and para-methoxyphenyl(2-thienyl)iodonium bromides, iodides, tosylates and triflates were synthesised. In addition, para-substituted (R=BnO, CH{sub 3}, H, Cl, Br, I) aryl(2-thienyl)iodonium bromides were prepared as precursors with a systematically varying electron density. As first approach, the general reaction conditions of the nucleophilic {sup 18}F-substitution procedure were optimised. The best conditions for direct nucleophilic no-carrier-added {sup 18}F-labelling via aryl(2-thienyl)iodonium salts were found with dimethylformamide as solvent, a reaction temperature of 130{+-}3 C and 25 mmol/l as concentration of the precursor. (orig.)

  8. One molecule of ionic liquid and tert-alcohol on a polystyrene-support as catalysts for efficient nucleophilic substitution including fluorination.

    Science.gov (United States)

    Shinde, Sandip S; Patil, Sunil N

    2014-12-07

    The tert-alcohol and ionic liquid solvents in one molecule [mim-(t)OH][OMs] was immobilized on polystyrene and reported to be a highly efficient catalyst in aliphatic nucleophilic substitution using alkali metal salts. Herein, we investigated the catalytic activity of a new structurally modified polymer-supported tert-alcohol functionalized imidazolium salt catalyst in nucleophilic substitution of 2-(3-methanesulfonyloxypropyoxy)naphthalene as a model substrate with various metal nucleophiles. The tert-alcohol moiety of the ionic liquid with a hexyl chain distance from polystyrene had a better catalytic activity compared to the other resin which lacked an alkyl linker and tert-alcohol moiety. We found that the maximum [mim-(t)OH][OMs] loading had the best catalytic efficacy among the tested polystyrene-based ionic liquids (PSILs) in nucleophilic fluorination. The catalytic efficiency of the PS[him-(t)OH][OMs] as a phase transfer catalyst (PTC) was determined by carrying out various nucleophilic substitutions using the corresponding alkali metal salts from the third to sixth periodic in CH3CN or tert-BuOH media. The scope of this protocol with primary and secondary polar substrates containing many heteroatoms is also reported. This PS[him-(t)OH][OMs] catalyst not only enhances the reactivity of alkali metal salts and reduces the formation of by-products but also affords high yield with easy isolation.

  9. The effect of varying the anion of an ionic liquid on the solvent effects on a nucleophilic aromatic substitution reaction.

    Science.gov (United States)

    Hawker, Rebecca R; Haines, Ronald S; Harper, Jason B

    2018-05-09

    A variety of ionic liquids, each containing the same cation but a different anion, were examined as solvents for a nucleophilic aromatic substitution reaction. Varying the proportion of ionic liquid was found to increase the rate constant as the mole fraction of ionic liquid increased demonstrating that the reaction outcome could be controlled through varying the ionic liquid. The solvent effects were correlated with the hydrogen bond accepting ability (β) of the ionic liquid anion allowing for qualitative prediction of the effect of changing this component of the solute. To determine the microscopic origins of the solvent effects, activation parameters were determined through temperature-dependent kinetic analyses and shown to be consistent with previous studies. With the knowledge of the microscopic interactions in solution, an ionic liquid was rationally chosen to maximise rate enhancement demonstrating that an ionic solvent can be selected to control reaction outcome for this reaction type.

  10. NCA nucleophilic radiofluorination on substituted benzaldehydes for the preparation of [18F]fluorinated aromatic amino acids

    International Nuclear Information System (INIS)

    Wadsak, Wolfgang; Wirl-Sagadin, Barbara; Mitterhauser, Markus; Mien, Leonhard-Key; Ettlinger, Dagmar E.; Keppler, Bernhard K.; Dudczak, Robert; Kletter, Kurt

    2006-01-01

    Nucleophilic aromatic substitution is a challenging task in radiochemistry. Therefore, a thorough evaluation and optimisation of this step is needed to provide a satisfactory tool for the routine preparation of [ 18 F]fluorinated aromatic amino acids. Two methods, already proposed elsewhere, were evaluated and improved. The yields for the radiofluorination were increased whereas activity loss during solid phase extraction was observed. Radiochemical yields for the two methods were 92.7±5.5% (method 1) and 92.1±12.3% (method 2) for conversion and 11.1±2.8% (method 1) and 34.8±0.6% (method 2) for purification, respectively. In total, we demonstrate an optimised method for the preparation of this important class of [ 18 F]fluorinated synthons for PET

  11. The synthesis of no-carrier-added DL-4-[18F]fluorodeprenyl via the nucleophilic aromatic substitution reaction

    International Nuclear Information System (INIS)

    Plenevaux, Alain; Guillaume, Marcel

    1991-01-01

    No-carrier-added DL-α-methyl-β-4-[ 18 F]fluorophenyl-N-methyl-N-propynylethylamine (DL-4-[ 18 F]fluorodeprenyl) was synthesized via a 3-step procedure. The overall yield was 11%, the synthesis time was 90 min and the specific activity >0.57 Ci/μmol (end of synthesis). This synthesis approach, the conversion of an aromatic aldehyde to a homologous methyl ketone, extends the flexibility of the nucleophilic aromatic substitution reaction by applying it to the synthesis of radiotracers which do not bear electron-withdrawing activating groups on the aromatic ring. The tissue distribution of DL-4-[ 18 F]fluorodeprenyl in mice at 1, 10 and 50 min was also measured and showed that metabolic defluorination was not significant. Clearance or radioactivity from brain after injection of DL-4-[ 18 F]fluorodeprenyl was more rapid than that previously observed for [ 11 C]L-deprenyl. (author)

  12. Dechlorination of chloropicrin and 1,3-dichloropropene by hydrogen sulfide species: redox and nucleophilic substitution reactions.

    Science.gov (United States)

    Zheng, Wei; Yates, Scott R; Papiernik, Sharon K; Guo, Mingxin; Gan, Jianying

    2006-03-22

    The chlorinated fumigants chloropicrin (trichloronitromethane) and 1,3-dichloropropene (1,3-D) are extensively used in agricultural production for the control of soilborne pests. The reaction of these two fumigants with hydrogen sulfide species (H2S and HS-) was examined in well-defined anoxic aqueous solutions. Chloropicrin underwent an extremely rapid redox reaction in the hydrogen sulfide solution. Transformation products indicated reductive dechlorination of chloropicrin by hydrogen sulfide species to produce dichloro- and chloronitromethane. The transformation of chloropicrin in hydrogen sulfide solution significantly increased with increasing pH, indicating that H2S is less reactive toward chloropicrin than HS- is. For both 1,3-D isomers, kinetics and transformation products analysis revealed that the reaction between 1,3-D and hydrogen sulfide species is an S(N)2 nucleophilic substitution process, in which the chlorine at C3 of 1,3-D is substituted by the sulfur nucleophile to form corresponding mercaptans. The 50% disappearance time (DT50) of 1,3-D decreased with increasing hydrogen sulfide species concentration at a constant pH. Transformation of 1,3-D was more rapid at high pH, suggesting that the reactivity of hydrogen sulfide species in the experimental system stems primarily from HS-. Because of the relatively low smell threshold values and potential environmental persistence of organic sulfur products yielded by the reaction of 1,3-D and HS-, the effects of reduced sulfide species should be considered in the development of alternative fumigation practices, especially in the integrated application of sulfur-containing fertilizers.

  13. Synthesis and reactivity of novel sulfur pentafluorides-Effect of the SF5 group on reactivity of nitrobenzenes in nucleophilic substitution

    Czech Academy of Sciences Publication Activity Database

    Beier, Petr

    2017-01-01

    Roč. 192, č. 2 (2017), s. 212-215 ISSN 1042-6507. [International Symposium on the Organic Chemistry of Sulfur (ISOCS) /27./. Jena, 26.07.2016-29.07.2016] Institutional support: RVO:61388963 Keywords : nucleophilic substitution * sulfur * fluorine * reaction rate Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 0.809, year: 2016

  14. The features of nucleophilic substitution of the nitro group in 4-alkyl-6-nitro-1,2,4-triazolo[5,1-c][1,2,4]triazines

    Directory of Open Access Journals (Sweden)

    E. N. Ulomsky

    2017-05-01

    Full Text Available The nucleophilic substitution of the nitro group of 4-alkyl-6-nitro-4,7-dihydro-1,2,4-triazolo[5,1-c][1,2,4]triazine-7-ones on the example of interactionwith morpholine was studied. It is established that under the action of excess cycloalkylimine at room temperature the unusual easy disclosure of triazine cycle with the formation of sterically hindered hydrazones occurs which are the key intermediates for further transformations. The carrying of reaction at elevated temperatures leads to the formation of products of substitution of the nitro group with the amine and also with morpholyl hydrazones which are the products of hydrolysis of amides of hydrazones and subsequent decarboxylation. Thus, the nucleophilic substitution of the nitro group in the described triazolotriazines flows through the ANRORC mechanism.

  15. Novel organophosphorus scaffolds of urease inhibitors obtained by substitution of Morita-Baylis-Hillman adducts with phosphorus nucleophiles.

    Science.gov (United States)

    Ntatsopoulos, Vassilis; Vassiliou, Stamatia; Macegoniuk, Katarzyna; Berlicki, Łukasz; Mucha, Artur

    2017-06-16

    The reactivity of Morita-Baylis-Hillman allyl acetates was employed to introduce phosphorus-containing functionalities to the side chain of the cinnamic acid conjugated system by nucleophilic displacement. The proximity of two acidic groups, the carboxylate and phosphonate/phosphinate groups, was necessary to form interactions in the active site of urease by recently described inhibitor frameworks. Several organophosphorus scaffolds were obtained and screened for inhibition of the bacterial urease, an enzyme that is essential for survival of urinary and gastrointestinal tract pathogens. α-Substituted phosphonomethyl- and 2-phosphonoethyl-cinnamate appeared to be the most potent and were further optimized. As a result, one of the most potent organophosphorus inhibitors of urease, α-phosphonomethyl-p-methylcinnamic acid, was identified, with K i  = 0.6 μM for Sporosarcina pasteurii urease. High complementarity to the enzyme active site was achieved with this structure, as any further modifications significantly decreased its affinity. Finally, this work describes the challenges faced in developing ligands for urease. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  16. Chromo- and fluorophoric water-soluble polymers and silica particles by nucleophilic substitution reaction of poly(vinyl amine

    Directory of Open Access Journals (Sweden)

    Katja Hofmann

    2010-07-01

    Full Text Available Novel chromophoric and fluorescent carbonitrile-functionalized poly(vinyl amine (PVAm and PVAm/silica particles were synthesized by means of nucleophilic aromatic substitution of 8-oxo-8H-acenaphtho[1,2-b]pyrrol-9-carbonitrile (1 with PVAm in water. The water solubility of 1 has been mediated by 2,6-O-β-dimethylcyclodextrin or by pre-adsorption onto silica particles. Furthermore, 1 was converted with isopropylamine into the model compound 1-M. All new compounds were characterized by NMR, FTIR, UV–vis and fluorescence spectroscopy. The solvent-dependent UV–vis absorption and fluorescence emission band positions of the model compound and the carbonitrile-functionalized PVAm were studied and interpreted using the empirical Kamlet–Taft solvent parameters π* (dipolarity/polarizability, α (hydrogen-bond donating capacity and β (hydrogen-accepting ability in terms of the linear solvation energy relationship (LSER. The solvent-independent regression coefficients a, b and s were determined using multiple linear correlation analysis. It is shown, that the chains of the polymer have a significant influence on the solvatochromic behavior of 1-P. The structure of the carbonitrile 1-Si bound to polymer-modified silica particles was studied by means of X-ray photoelectron spectroscopy (XPS and Brunauer–Emmett–Teller (BET measurements. Fluorescent silica particles were obtained as shown by fluorescence spectroscopy with a diffuse reflectance technique.

  17. One-pot regioselective synthesis of nitrophenyloxazolinyl styrene oxides by the Darzens reaction of vicarious nucleophilic substitution-formed carbanions of 2-dichloromethyl-4,4-dimethyloxazoline.

    Science.gov (United States)

    Florio, Saverio; Lorusso, Patrizia; Granito, Catia; Luisi, Renzo; Troisi, Luigino

    2004-07-23

    The vicarious nucleophilic substitution reaction of dichloromethyloxazoline 2 with nitrobenzene has been investigated. Treatment of 2 with t-BuOK followed by the addition of nitrobenzene leads to benzylic carbanions 4 or 9 depending upon the solvent used (DMSO, DMF, or THF). Subsequent treatment of 4 or 9 with aldehydes, in a Darzens-like reaction, furnishes very good yields of nitrophenyl oxazolinyloxiranes 8 and 11. 1,2-Dioxazolinyl-1,2-dinitrophenylethene 7 forms quantitatively when carbanion 4 is allowed to warm to room temperature in the absence of external electrophiles.

  18. New Method for Nucleophilic Substitution on Hexachlorocyclotriphosphazene by Allylamine Using an Algerian Proton Exchanged Montmorillonite Clay (Maghnite-H+ as a Green Solid Catalyst

    Directory of Open Access Journals (Sweden)

    Lahouaria Medjdoub

    2016-08-01

    Full Text Available Nucleophilic substitution on hexachlorocyclotriphosphazene (HCCTP with allylamine in order to give hexa(allylaminocyclotriphosphazene (HACTP  is performed for the first time under mild conditions by using diethylether as solvent to replace benzene which is very toxic. The reaction time is reduced to half and also performed at room temperature but especially in the presence of an eco-catalyst called Maghnite-H+. This catalyst has a significant role in the industrial scale. In fact, the use of Maghnite is preferred for its many advantages: a very low purchase price compared to other catalysts, the easy removal of the reaction mixture. Then, Maghnite-H+ is became an excellent catalyst for many chemical reactions. The structure of HACTP synthesized in the presence of Maghnite-H+ to 5% by weight is confirmed by 1H-NMR, 13C-NMR, 31P-NMR (Nuclear magnetic resonance and FTIR (Fourier Transform Infrared spectroscopy. MALDI-TOF (Matrix-Assisted Laser Desorption/Ionisation-time-of-flight mass spectrometry is used to establish the molecular weight of HACTP which is 471 g/mol. DSC (Differential Scanning Calorimetery and TGA (Thermogravimetric Analysis show that HACTP is a crystalline product with a melting point of 88 °C. It is reactive after melting but is degraded from 230 °C. Copyright © 2016 BCREC GROUP. All rights reserved Received: 28th September 2015; Revised: 5th December 2015; Accepted: 4th January 2016 How to Cite: Medjdoub, L., Mohammed, B. (2016. New Method for Nucleophilic Substitution on Hexachlorocyclotriphosphazene by Allylamine Using an Algerian Proton Exchanged Montmorillonite Clay (Maghnite-H+ as a Green Solid Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (2: 151-160 (doi:10.9767/bcrec.11.2.541.151-160 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.2.541.151-160

  19. New dinuclear palladium(II) complexes: Studies of the nucleophilic substitution reactions, DNA/BSA interactions and cytotoxic activity.

    Science.gov (United States)

    Ćoćić, Dušan; Jovanović, Snežana; Nišavić, Marija; Baskić, Dejan; Todorović, Danijela; Popović, Suzana; Bugarčić, Živadin D; Petrović, Biljana

    2017-10-01

    Six new dinuclear Pd(II) complexes, [{Pd(2,2'-bipy)Cl} 2 (μ-pz)](ClO 4 ) 2 (Pd1), [{Pd(dach)Cl} 2 (μ-pz)](ClO 4 ) 2 (Pd2), [{Pd(en)Cl} 2 (μ-pz)](ClO 4 ) 2 (Pd3), [{Pd(2,2'-bipy)Cl} 2 (μ-4,4'-bipy)](ClO 4 ) 2 (Pd4), [{Pd(dach)Cl} 2 (μ-4,4'-bipy)](ClO 4 ) 2 (Pd5) and [{Pd(en)Cl} 2 (μ-4,4'-bipy)](ClO 4 ) 2 (Pd6) (where 2,2'-bipy=2,2'-bipyridyl, pz=pyrazine, dach=trans-(±)-1,2-diaminocyclohexane, en=ethylenediamine, 4,4'-bipy=4,4'-bipyridyl) have been synthesized and characterized by elemental microanalysis, IR, 1 H NMR and MALDI-TOF mass spectrometry. The pK a values of corresponding diaqua complexes were determined by spectrophotometric pH titration. Substitution reactions with thiourea (Tu), l-methionine (l-Met), l-cysteine (l-Cys), l-histidine (l-His) and guanosine-5'-monophosphate (5'-GMP) were studied under the pseudo-first order conditions at pH7.2. Reactions of Pd1 with Tu, l-Met and l-Cys were followed by decomposition of complexes, while structures of dinuclear complexes were preserved during the substitution with nitrogen donors. Interactions with calf-thymus DNA (CT-DNA) were followed by absorption spectroscopy and fluorescence quenching measurements. All complexes can bind to CT-DNA exhibiting high intrinsic binding constants (K b =10 4 -10 5 M -1 ). Competitive studies with ethidium bromide (EB) have shown that complexes can displace DNA-bound EB. High values of binding constants towards bovine serum albumin protein (BSA) indicate good binding affinity. Finally, all complexes showed moderate to high cytotoxic activity against HeLa (human cervical epithelial carcinoma cell lines) and MDA-MB-231 (human breast epithelial carcinoma cell lines) tumor cell lines inducing apoptotic type cell death, whereas normal fibroblasts were significantly less sensitive. The impact on cell cycle of these cells was distinctive, where Pd4, Pd5 and Pd6 showed the most prominent effect arresting MDA-MB-231 (human lung fibroblast cell lines) cell in G1/S phase of cell

  20. Chemical dynamics simulations of X- + CH3Y → XCH3 + Y- gas-phase S(N)2 nucleophilic substitution reactions. Nonstatistical dynamics and nontraditional reaction mechanisms.

    Science.gov (United States)

    Manikandan, Paranjothy; Zhang, Jiaxu; Hase, William L

    2012-03-29

    Extensive classical chemical dynamics simulations of gas-phase X(-) + CH(3)Y → XCH(3) + Y(-) S(N)2 nucleophilic substitution reactions are reviewed and discussed and compared with experimental measurements and predictions of theoretical models. The primary emphasis is on reactions for which X and Y are halogen atoms. Both reactions with the traditional potential energy surface (PES), which include pre- and postreaction potential energy minima and a central barrier, and reactions with nontraditional PESs are considered. These S(N)2 reactions exhibit important nonstatistical atomic-level dynamics. The X(-) + CH(3)Y → X(-)---CH(3)Y association rate constant is less than the capture model as a result of inefficient energy transfer from X(-)+ CH(3)Y relative translation to CH(3)Y rotation and vibration. There is weak coupling between the low-frequency intermolecular modes of the X(-)---CH(3)Y complex and higher frequency CH(3)Y intramolecular modes, resulting in non-RRKM kinetics for X(-)---CH(3)Y unimolecular decomposition. Recrossings of the [X--CH(3)--Y](-) central barrier is important. As a result of the above dynamics, the relative translational energy and temperature dependencies of the S(N)2 rate constants are not accurately given by statistical theory. The nonstatistical dynamics results in nonstatistical partitioning of the available energy to XCH(3) +Y(-) reaction products. Besides the indirect, complex forming atomic-level mechanism for the S(N)2 reaction, direct mechanisms promoted by X(-) + CH(3)Y relative translational or CH(3)Y vibrational excitation are possible, e.g., the roundabout mechanism.

  1. Kinetic Study on Nucleophilic Substitution Reactions of 4-Chloro-2-nitrophenyl X-Substituted-benzoates with Cyclic Secondary Amines: Effect of Substituent X on Reactivity and Reaction Mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Seong Hoon; Kim, Hyun Soo; Han, Young Joon [Sejong Science High School, Seoul (Korea, Republic of); Kim, Minyoung; Um, Ikhwan [Ewha Woman' s Univ., Seoul (Korea, Republic of)

    2013-10-15

    Second-order rate constants (k{sub N}) have been measured spectrophotometrically for the reactions of 4-chloro-2-nitrophenyl X-substituted-benzoates (1a-1h) with a series of cyclic secondary amines in 80 mol % H{sub 2}O/20 mol % DMSO at 25.0 ± 0.1 .deg. C. The Hammett plot for the reactions of 1a-1h with piperidine consists of two intersecting straight lines, while the Yukawa-Tsuno plot exhibits an excellent linear correlation with ρ{sub X} = 1.25 and r = 0.58, indicating that the nonlinear Hammett plot is not due to a change in the rate-determining step (RDS) but is caused by ground-state stabilization through resonance interactions for substrates possessing an electron-withdrawing group in the benzoyl moiety. The Brφnsted-type plot for the reactions of 4-chloro-2-nitrophenyl benzoate (1d) with a series of cyclic secondary amines curves downward with β{sub 2} = 0.85, β{sub 1} = 0.24, and pK{sub a}{sup o} = 10.5, implying that a change in RDS occurs from the k{sub 2} step to the k{sub 1} process as the pK{sub a} of the conjugate acid of the amine exceeds 10.5. Dissection of k{sub N} into the microscopic rate constants k{sub 1} and k{sub 2}/k{sub -1} ratio associated with the reaction of 1d reveals that k{sub 2} is dependent on the amine basicity, which is contrary to generally held views.

  2. Use of fluorine-18 free of carrier for the synthesis of 2-[18 F]-fluoro-2-deoxy-d-glucose by nucleophilic substitution

    International Nuclear Information System (INIS)

    Garcia S, I.; Ramirez, F.M.

    1990-11-01

    Preliminary studies on the synthesis of 2 - [ 18 F]-fluoro-2-deoxy-d-glucose (2 - [ 18 F]-FDG) were carried out by means of the nucleophilic method proposed by K. Hamacher and the 18 F obtained in the Nuclear Reactor TRIGA Mark III of the Nuclear Center of Mexico. For the control of radiochemical quality it was used the chromatography technique in paper and silica gel with 4 solvent systems. The identification of the marked species with 18 F was carried out by means of comparison of its Rf with the Rf of the obtained not radioactive species, using the same synthesis method. (Author)

  3. Nucleophilic addition to olefins. 7. Kinetic deuterium isotope effects as criterion for an enforced preassociation mechanism in the hydrolysis of substituted benzylidene Meldrum's acids

    International Nuclear Information System (INIS)

    Bernasconi, C.F.; Leonarduzzi, G.D.

    1982-01-01

    The hydrolysis of the title compounds occurs in four steps: (1) nucleophilic attack by water or hydroxide ion to form the addition complex T/sub OH/ - ; (2) carbon protonation of T/sub OH/ - to form T/sub OH/ 0 ; (3) oxygen deprotonation of T/sub OH/ 0 to form T/sub OH/ 0 - ; (4) collapse of the tetrahedral intermediate T/sub OH/ - into the respective benzaldehyde and Meldrum's acid anion. There is also a water-catalyzed collapse of T/sub OH/ 0 which becomes dominant in strongly acidic solution. In basic solution carbon protonation of T/sub OH/ - (step 2) is rate limiting; in strongly acidic media the water-catalyzed collapse of T/sub OH/ 0 is rate limiting for all substrates. In moderatly acidic solution two types of behavior were observed. With the p-nitro derivative step 4 is rate limiting at high, step 3 at low buffer concentrations. The latter situation is equivalent to a diffusion-controlled trapping mechanism in the reverse direction. With the parent and the p-methoxy derivative, collapse of T/sub OH/ 0 - occurs before the protonated base catalyst generated in step 3 can diffuse away; this is equivalent to an enforced preassociation mechanism in the reverse direction and is analogous to the reaction of thiol anions with acetaldehyde studied by Gilbert and Jencks. Our interpretation is strongly supported by (1) α secondary kinetic deuterium isotope effects which are large for the preassociation mechanism but essentially nil for the trapping mechanism and (2) by Bronsted #betta# values around 0.8 in the case of the preassociation mechanism and 1.0 for the trapping mechanism. The mechanism for the water-catalyzed collapse of T/sub OH/ 0 - is probably concerted, a conclusion which is supported by a large positive deviation from the Bronsted plot for base catalysis and by a large α secondary kinetic deuterium isotope effect

  4. Kinetic study on S_NAr reactions of 1-(Y-Substituted-phenoxy)-2,4-dinitrobenzenes with azide ion: Effect of changing nucleophile from hydroxide to zzide ion on reaction mechanism and reactivity

    International Nuclear Information System (INIS)

    Seo, Hyeon Ok; Kim, Min Young; Han, So Yeop; Um, Ik Hwan

    2015-01-01

    Second-order rate constants (k_N_3_−) for SNAr reactions of 1-(Y-substituted-phenoxy)-2,4-dinitrobenzenes (2a–2h) with math formula in 80 mol % H_2O/20 mol % DMSO at 25.0 ± 0.1 °C have been measured spectrophotometrically. The Brønsted-type plot is linear with β"l"g = −0.38. The Hammett plots correlated with math formula and math formula constants exhibit highly scattered points. In contrast, the Yukawa–Tsuno plot results in an excellent linear correlation with ρ_Y = 1.02 and r = 0.51, indicating that a negative charge develops partially on the O atom of the leaving Y-substituted-phenoxy moiety in the transition state. Accordingly, the reactions have been concluded to proceed through a stepwise mechanism, in which expulsion of the leaving group occurs in the rate-determining step. Comparison of k_N_3_− with the k_O_H_− values reported previously for the corresponding reactions with OH"− has revealed that math formula is only 6- to 26-fold less reactive than OH"− toward substrates 2a–2h, although the former is over 11 pK_a units less basic than the latter. Solvation and polarizability effects have been suggested to be responsible for the unusual reactivity shown by math formula and OH"−. Effects of changing nucleophile from OH"− to N_3"− on reaction mechanism and reactivity are discussed in detail

  5. Erosion of stereochemical control with increasing nucleophilicity: O-glycosylation at the diffusion limit.

    Science.gov (United States)

    Beaver, Matthew G; Woerpel, K A

    2010-02-19

    Nucleophilic substitution reactions of 2-deoxyglycosyl donors indicated that the reactivity of the oxygen nucleophile has a significant impact on stereoselectivity. Employing ethanol as the nucleophile resulted in a 1:1 (alpha:beta) ratio of diastereomers under S(N)1-like reaction conditions. Stereoselective formation of the 2-deoxy-alpha-O-glycoside was only observed when weaker nucleophiles, such as trifluoroethanol, were employed. The lack of stereoselectivity observed in reactions of common oxygen nucleophiles can be attributed to reaction rates of the stereochemistry-determining step that approach the diffusion limit. In this scenario, both faces of the prochiral oxocarbenium ion are subject to nucleophilic addition to afford a statistical mixture of diastereomeric products. Control experiments confirmed that all nucleophilic substitution reactions were performed under kinetic control.

  6. XVIII Mendeleev congress on general and applied chemistry. Summaries of reports in five volumes. Volume 5. IV Russian-French symposium Supramolecular systems in chemistry and biology. II Russian-Indian symposium on organic chemistry. International symposium on present-day radiochemistry Radiochemistry: progress and prospects. International symposium Green chemistry, stable evolution and social responsibility of chemists. Symposium Nucleophilic hydrogen substitution in aromatic systems and related reactions

    International Nuclear Information System (INIS)

    2007-01-01

    The 5 volume of the XVIII Mendeleev congress on general and applied chemistry includes summaries of reports on the subjects of sypramolecular systems in chemistry and biology, organic chemistry, modern radiochemistry, green chemistry - development and social responsibility of chemists, nucleophilic hydrogen substitution in aromatic systems and related chemical reactions [ru

  7. Bimolecular reactions of carbenes: Proton transfer mechanism

    Science.gov (United States)

    Abu-Saleh, Abd Al-Aziz A.; Almatarneh, Mansour H.; Poirier, Raymond A.

    2018-04-01

    Here we report the bimolecular reaction of trifluoromethylhydroxycarbene conformers and the water-mediated mechanism of the 1,2-proton shift for the unimolecular trans-conformer by using quantum chemical calculations. The CCSD(T)/cc-pVTZ//MP2/cc-pVDZ potential-energy profile of the bimolecular reaction of cis- and trans-trifluoromethylhydroxycarbene, shows the lowest gas-phase barrier height of 13 kJ mol-1 compared to the recently reported value of 128 kJ mol-1 for the unimolecular reaction. We expect bimolecular reactions of carbene's stereoisomers will open a valuable field for new and useful synthetic strategies.

  8. Kinetic study on alkaline hydrolysis of Y-substituted phenyl X-substituted benzenesulfonates: Effects of changing nucleophile from azide to hydroxide ion on reactivity and transition-state structure

    International Nuclear Information System (INIS)

    Moon, Ji Hyun; Kim, Min Young; Han, So Yeop; Um, Ik Hwan

    2015-01-01

    Second-order rate constants (math formula) for alkaline hydrolysis of 2,4-dinitrophenyl X-substituted benzenesulfonates (1a–1f) and Y-substituted phenyl 4-nitrobezenesulfonates (2a–2g) have been measured spectrophotometrically. Comparison of math formula with the math formula values reported previously for the corresponding reactions with math formula has revealed that OH [BOND] is only 10"3-fold more reactive than math formula, although the former is 11 pK _a units more basic than the latter. The Yukawa–Tsuno plot for the reactions of 1a–1f results in an excellent linear correlation with ρ_X = 2.09 and r = 0.41. The Brønsted-type plot for the reactions of 2a–2g is linear with β_l_g = −0.51, which is typical for reactions reported to proceed through a concerted mechanism. The Yukawa–Tsuno plot for the reactions of 2a–2g exhibits excellent linearity with ρ_Y = 1.85 and r = 0.25, indicating that a partial negative charge develops on the O atom of the leaving group in the transition state. Thus, the alkaline hydrolysis of 1a–1f and 2a–2g has been concluded to proceed through a concerted mechanism. Comparison of the ρ_X and β_l_g values for the reactions with math formula ions suggests that the reactions with hydroxide ion proceed through a tighter transition-state structure than those with azide ion

  9. α-deuterium isotope effects in benzyl halides. 2. Reaction of nucleophiles with substituted benzyl bromides. Evidence for a change in transition-state structure with electron-donating substituents

    International Nuclear Information System (INIS)

    Vitullo, V.P.; Grabowski, J.; Sridharan, S.

    1980-01-01

    Rates and α-D isotope effects have been determined for the following substrates and nucleophiles: p-methoxybenzyl bromide (Et 3 N, SCN - , N 3 - , OH - , S 2 O 3 2- ), benzyl bromide (Et 3 N, SCN - , N 3 - , OH - , S 2 O 3 2- ), and p-nitrobenzyl bromide (Et 3 N, SCN - , N 3 - , S 2 O 3 2- ). In nearly all cases the second-order rate constant for each nucleophile goes through a minimum for the unsubstituted compound while the α-D isotope increases monotonically in the squence p-NO 2 > p-H > p-OCH 3 . These results are consistent with an increasing looseness of the S/sub N/2 transition state as the substituent on the aromatic ring becomes more electron donating. 4 figures, 3 tables

  10. Conjugate Addition of Nucleophiles to the Vinyl Function of 2-Chloro-4-vinylpyrimidine Derivatives

    Directory of Open Access Journals (Sweden)

    Lucjan Strekowski

    2010-03-01

    Full Text Available Conjugate addition reaction of various nucleophiles across the vinyl group of 2-chloro-4-vinylpyrimidine, 2-chloro-4-(1-phenylvinylpyrimidine and 2-chloro-4-vinylquinazoline provides the corresponding 2-chloro-4-(2-substituted ethylpyrimidines and 2-chloro-4-(2-substituted ethylquinazolines. Treatment of these products, without isolation, with N-methylpiperazine results in nucleophilic displacement of chloride and yields the corresponding 2,4-disubstituted pyrimidines and quinazolines.

  11. Optimization studies concerning the direct nucleophilic fluorination of butyrophenone neuroleptics

    Energy Technology Data Exchange (ETDEWEB)

    Katsifis, A; Hamacher, K; Schnitter, J; Stoecklin, G [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Chemie 1 - Nuklearchemie

    1993-07-01

    Based on the direct nucleophilic aromatic substitution described previously for [[sup 18]F]N-methylspiperone the butyrophenone neuroleptics benperidol, droperidol, fluanisone and haloperidol were labelled with fluorine-18. The n.c.a. aromatic nucleophilic NO[sub 2] [yields] [sup 18]F substitution takes place in the presence of the moderately basic cryptate system consisting of Kryptofix 2.2.2., potassium oxalate and potassium carbonate. The one step labeling reaction was performed in different solvents and is equally successful in dimethylsulfoxide, dimethylformamide or dimethylacetamide yielding 25-35% (EOS) within a reaction time of 5-30 min in the range of 140-160[sup o]C at analytical activity levels. (author).

  12. Observation of correlated excitations in bimolecular collisions

    Science.gov (United States)

    Gao, Zhi; Karman, Tijs; Vogels, Sjoerd N.; Besemer, Matthieu; van der Avoird, Ad; Groenenboom, Gerrit C.; van de Meerakker, Sebastiaan Y. T.

    2018-02-01

    Although collisions between atoms and molecules are largely understood, collisions between two molecules have proven much harder to study. In both experiment and theory, our ability to determine quantum-state-resolved bimolecular cross-sections lags behind their atom-molecule counterparts by decades. For many bimolecular systems, even rules of thumb—much less intuitive understanding—of scattering cross sections are lacking. Here, we report the measurement of state-to-state differential cross sections on the collision of state-selected and velocity-controlled nitric oxide (NO) radicals and oxygen (O2) molecules. Using velocity map imaging of the scattered NO radicals, the full product-pair correlations of rotational excitation that occurs in both collision partners from individual encounters are revealed. The correlated cross sections show surprisingly good agreement with quantum scattering calculations using ab initio NO-O2 potential energy surfaces. The observations show that the well-known energy-gap law that governs atom-molecule collisions does not generally apply to bimolecular excitation processes, and reveal a propensity rule for the vector correlation of product angular momenta.

  13. Synthesis and structure of aromatic and heterocyclic tellurium compounds 33. Synthesis of [2-(aryltelluro)vinyl]aldehydes and ketones and stereochemistry of nucleophilic substitution under vinyl atom of carbon

    International Nuclear Information System (INIS)

    Sadekov, I.D.; Rivkin, B.B.; Zakharov, A.V.; Minkin, V.I.

    1996-01-01

    By means of interaction of (2-vinylchlorida) carbonyl compounds and (2-acylvinyl) triethylammonium chlorides and arenetellurolate-anions certain, [2-(aryltelluro)vinyl]ketones and [2-(aryltelluro)vinyl]aldehydes have been synthesized, while by means of reaction between 2-aroylvinyl chlorides and Li 2 Te some di(2-aroylvinyl)tellurides have been prepared. Interaction of (2-vinylchloride)ketones with arenetellurolate-anions always gives rise to Z-isomers of [2-(aryltelluro)vinyl]ketones as a result of stabilization of intermediate carbanion by intramolecular coordination O→Te. Nucleophilic addition of arenetellurolate-anions to α-acetylene aldehydes and ketones occurs as trans-addition. 36 refs., 2 figs., 1 tab

  14. Arylazoindazole Photoswitches : Facile Synthesis and Functionalization via SNAr Substitution

    NARCIS (Netherlands)

    Travieso-Puente, Raquel; Budzak, Simon; Chen, Juan; Stacko, Peter; Jastrzebski, Johann T B H; Jacquemin, Denis; Otten, Edwin

    2017-01-01

    A straightforward synthetic route to arylazoindazoles via nucleophilic aromatic substitution is presented. Upon deprotonation of the NH group, a C6F5-substituted formazan undergoes facile cyclization as a result of intermolecular nucleophilic substitution (SNAr). This new class of azo photoswitches

  15. Self-assembled tethered bimolecular lipid membranes.

    Science.gov (United States)

    Sinner, Eva-Kathrin; Ritz, Sandra; Naumann, Renate; Schiller, Stefan; Knoll, Wolfgang

    2009-01-01

    This chapter describes some of the strategies developed in our group for designing, constructing and structurally and functionally characterizing tethered bimolecular lipid membranes (tBLM). We introduce this platform as a novel model membrane system that complements the existing ones, for example, Langmuir monolayers, vesicular liposomal dispersions and bimolecular ("black") lipid membranes. Moreover, it offers the additional advantage of allowing for studies of the influence of membrane structure and order on the function of integral proteins, for example, on how the composition and organization of lipids in a mixed membrane influence the ion translocation activity of integral channel proteins. The first strategy that we introduce concerns the preparation of tethered monolayers by the self-assembly of telechelics. Their molecular architecture with a headgroup, a spacer unit (the "tether") and the amphiphile that mimics the lipid molecule allows them to bind specifically to the solid support thus forming the proximal layer of the final architecture. After fusion of vesicles that could contain reconstituted proteins from a liposomal dispersion in contact to this monolayer the tethered bimolecular lipid membrane is obtained. This can then be characterized by a broad range of surface analytical techniques, including surface plasmon spectroscopies, the quartz crystal microbalance, fluorescence and IR spectroscopies, and electrochemical techniques, to mention a few. It is shown that this concept allows for the construction of tethered lipid bilayers with outstanding electrical properties including resistivities in excess of 10 MOmega cm2. A modified strategy uses the assembly of peptides as spacers that couple covalently via their engineered sulfhydryl or lipoic acid groups at the N-terminus to the employed gold substrate, while their C-terminus is being activated afterward for the coupling of, for example, dimyristoylphosphatidylethanol amine (DMPE) lipid molecules

  16. Convergent synthesis of 6-substituted phenanthridines via anionic ring closure

    DEFF Research Database (Denmark)

    Lysén, M.; Kristensen, Jesper Langgaard; Vedsø, P.

    2002-01-01

    Chemical equation presented The addition of organometallic derivatives to the cyano group of 2-(2-fluorophenyl)benzonitrile followed by intramolecular nucleophilic substitution produces 6-substituted phenanthridines. Alkyllithiums, aryllithiums, and sterically nondemanding lithium amides reacted ...

  17. Theoretical study on the nucleophilic fluoroalkylation of propylene oxide with fluorinated sulfones

    Directory of Open Access Journals (Sweden)

    Han Ling-Li

    2013-01-01

    Full Text Available The path of nucleophilic fluoroalkylation reaction of propylene oxide with PhSO2CYF- (Y=F,H, and PhSO2, respectively in gas phase and in Et2O solvent were studied theoretically. The nucleophilic fluoroalkylation of propylene oxide with fluorinated carbanions was probed by the reactivity comparison between (benzenesulfonylmonofluoromethyl anion (PhSO2CHF-, (benzenesulfonyl difluoromethyl anion (PhSO2CF2-, and bis(benzenesul-fonyl monofluoromethyl anion ((PhSO22CF-. The nucleophilicity reactivity order of PhSO2CYF- (Y = F, H, and PhSO2 is [(PhSO22CF-] > PhSO2CHF- > PhSO2CF2-, which indicates that introducing another electron-withdrawing benzenesulfonyl group is an effective way to significantly increase the nucleophilicity of the fluorinate carbanions. For comparison, we also studied the nucleophilic addition reactions of propylene oxide with chlorine substituted carbanion PhSO2CHCl-. The calculated results show that the nucleophilicity of PhSO2CYF- is better than that of PhSO2CHCl- for the ring opening reaction with propylene oxide. The calculated results are in good agreement with the available experiments.

  18. A quantitative approach to nucleophilic organocatalysis

    Directory of Open Access Journals (Sweden)

    Herbert Mayr

    2012-09-01

    Full Text Available The key steps in most organocatalytic cyclizations are the reactions of electrophiles with nucleophiles. Their rates can be calculated by the linear free-energy relationship log k(20 °C = sN(E + N, where electrophiles are characterized by one parameter (E and nucleophiles are characterized by the solvent-dependent nucleophilicity (N and sensitivity (sN parameters.Electrophilicity parameters in the range –10 E N N parameters of enamines derived from phenylacetaldehyde and MacMillan’s imidazolidinones one can rationalize why only strong electrophiles, such as stabilized carbenium ions (–8 E E = –6.75, are suitable electrophiles for enamine activated reactions with imidazolidinones. Several mechanistic controversies concerning iminium and enamine activated reactions could thus be settled by studying the reactivities of independently synthesized intermediates.Kinetic investigations of the reactions of N-heterocyclic carbenes (NHCs with benzhydrylium ions showed that they have similar nucleophilicities to common organocatalysts (e.g., PPh3, DMAP, DABCO but are much stronger (100–200 kJ mol–1 Lewis bases. While structurally analogous imidazolylidenes and imidazolidinylidenes have comparable nucleophilicities and Lewis basicities, the corresponding deoxy Breslow intermediates differ dramatically in reactivity. The thousand-fold higher nucleophilicity of 2-benzylidene-imidazoline relative to 2-benzylidene-imidazolidine is explained by the gain of aromaticity during electrophilic additions to the imidazoline derivatives. O-Methylated Breslow intermediates are a hundred-fold less nucleophilic than deoxy Breslow intermediates.

  19. Aliphatic Nucleophilic Radio-fluorination

    International Nuclear Information System (INIS)

    Roeda, D.; Dolle, F.

    2010-01-01

    In this review we are looking at some aspects of nucleophilic aliphatic radio-fluorination, notably the labelled fluoride source, design aspects, the leaving group and the solvent. It should be clear that there is more to this branch of radiolabelling than one would suspect from the frequently used standard tosylate replacement with kryptofix/[ 18 F]fluoride in acetonitrile or DMSO. Competitive elimination can be a serious problem that can affect both yield and purification. De-protection of sensitive groups after radiolabelling and its possible side reactions can complicate purification. The right choice of leaving group and protecting groups may be crucial. Newer developments such as the use of tertiary alcohols or ionic liquids as solvents, long-chain poly-fluorinated sulphonate leaving groups facilitating fluorous solid phase extraction, or immobilisation of the precursor on a solid phase support may help to solve these problems, for example the longstanding problems with [ 18 F]FLT, whereas older concepts such as certain cyclic reactive entities for ring opening or even an abandoned reagent as [ 18 F]DAST should not be forgotten. (authors)

  20. Nucleophilic addition of nitriles to secondary terpene alcohols

    International Nuclear Information System (INIS)

    Kozlov, N.G.; Popova, L.A.; Nesterov, G.V.

    1987-01-01

    The addition of nitriles of varying nucleophilicity to isocamphanol and exo-1,5,5-trimethyl-bicyclo[2.2.1]heptan-2-ol (isofenchol) was investigated. The authors examined the effect of the reaction conditions on the yield and structure of the target products of the reaction: N-substituted amides. As a result of the study, it was shown that in the reaction with chloroacetonitrile, propionitrile, methoxypropionitrile, isovaleronitrile, and phenylacetonitrile under the conditions of the Ritter reaction, isocamphanol is transformed into the corresponding substituted exo-N-acyl-1,7,7-trimethylbicyclo[2.2.1]hept-2-ylamines, as in the reaction with aceto- and benzonitriles, due to 2,6-hydride displacement accompanied by Wagner-Meerwein rearrangement. The structures of these amides were demonstrated by PMR spectroscopy

  1. Synthesis of New Cytotoxic Aminoanthraquinone Derivatives via Nucleophilic Substitution Reactions

    Directory of Open Access Journals (Sweden)

    Hasimah Alimon

    2013-07-01

    Full Text Available Aminoanthraquinones were successfully synthesized via two reaction steps. 1,4-Dihydroxyanthraquinone (1 was first subjected to methylation, reduction and acylation to give an excellent yield of anthracene-1,4-dione (3, 1,4-dimethoxyanthracene-9,10-dione (5 and 9,10-dioxo-9,10-dihydroanthracene-1,4-diyl diacetate (7. Treatment of 1, 3, 5 and 7 with BuNH2 in the presence of PhI(OAc2 as catalyst produced seven aminoanthraquinone derivatives 1a, b, 3a, and 5a–d. Amination of 3 and 5 afforded three new aminoanthraquinones, namely 2-(butylaminoanthracene-1,4-dione (3a, 2-(butylaminoanthracene-9,10-dione (5a and 2,3-(dibutylaminoanthracene-9,10-dione (5b. All newly synthesised aminoanthraquinones were examined for their cytotoxic activity against MCF-7 (estrogen receptor positive human breast and Hep-G2 (human hepatocellular liver carcinoma cancer cells using MTT assay. Aminoanthraquinones 3a, 5a and 5b exhibited strong cytotoxicity towards both cancer cell lines (IC50 1.1–13.0 µg/mL.

  2. DFT analysis of the nucleophilicity of substituted pyridines and ...

    Indian Academy of Sciences (India)

    the molecules in training and test sets indicated the vali- dity of the methods (see ...... Harris R L N, Huppatz J L, Phillips J N and Teitei T. 1979 In Advances in ... Geerlings P, De Proft F and Langenaeker W 2003 Chem. Rev. 103 1793. 17.

  3. Analysis of Brownian Dynamics Simulations of Reversible Bimolecular Reactions

    KAUST Repository

    Lipková, Jana

    2011-01-01

    A class of Brownian dynamics algorithms for stochastic reaction-diffusion models which include reversible bimolecular reactions is presented and analyzed. The method is a generalization of the λ-bcȳ model for irreversible bimolecular reactions which was introduced in [R. Erban and S. J. Chapman, Phys. Biol., 6(2009), 046001]. The formulae relating the experimentally measurable quantities (reaction rate constants and diffusion constants) with the algorithm parameters are derived. The probability of geminate recombination is also investigated. © 2011 Society for Industrial and Applied Mathematics.

  4. Construction of a bimolecular fluorescence complementation (BiFC ...

    African Journals Online (AJOL)

    Protein–protein interactions are essential for signal transduction in cells. Bimolecular fluorescence complementation (BiFC) is a novel technology that utilises green fluorescent proteins to visualize protein–protein interactions and subcellular protein localisation. BiFC based on pSATN vectors are a good system for ...

  5. Nucleophilic difluoromethylation and difluoromethylenation of aldehydes

    Czech Academy of Sciences Publication Activity Database

    Beier, Petr; Alexandrova, Anastasia; Zibinsky, M.; Prakash, G. K. S.

    2008-01-01

    Roč. 64, č. 49 (2008), s. 10977-10985 ISSN 0040-4020 R&D Projects: GA ČR GP203/08/P310 Institutional research plan: CEZ:AV0Z40550506 Keywords : difluoromethylation * difluoromethylenation * phosphonate * nucleophilic addition Subject RIV: CC - Organic Chemistry Impact factor: 2.897, year: 2008

  6. Ring opening of epoxides with C-nucleophiles.

    Science.gov (United States)

    Faiz, Sadia; Zahoor, Ameer Fawad

    2016-11-01

    Ring opening of epoxides has been an area of interest for organic chemists, owing to their reactivity toward nucleophiles. Such reactions yield important products depending on the type of nucleophiles used. This review article covers the synthetic approaches (1991-2015) used for the ring opening of epoxides via carbon nucleophiles.

  7. RPMDrate: Bimolecular chemical reaction rates from ring polymer molecular dynamics

    KAUST Repository

    Suleimanov, Yu.V.

    2013-03-01

    We present RPMDrate, a computer program for the calculation of gas phase bimolecular reaction rate coefficients using the ring polymer molecular dynamics (RPMD) method. The RPMD rate coefficient is calculated using the Bennett-Chandler method as a product of a static (centroid density quantum transition state theory (QTST) rate) and a dynamic (ring polymer transmission coefficient) factor. The computational procedure is general and can be used to treat bimolecular polyatomic reactions of any complexity in their full dimensionality. The program has been tested for the H+H2, H+CH 4, OH+CH4 and H+C2H6 reactions. © 2012 Elsevier B.V. All rights reserved.

  8. RPMDrate: Bimolecular chemical reaction rates from ring polymer molecular dynamics

    KAUST Repository

    Suleimanov, Yu.V.; Allen, J.W.; Green, W.H.

    2013-01-01

    We present RPMDrate, a computer program for the calculation of gas phase bimolecular reaction rate coefficients using the ring polymer molecular dynamics (RPMD) method. The RPMD rate coefficient is calculated using the Bennett-Chandler method as a product of a static (centroid density quantum transition state theory (QTST) rate) and a dynamic (ring polymer transmission coefficient) factor. The computational procedure is general and can be used to treat bimolecular polyatomic reactions of any complexity in their full dimensionality. The program has been tested for the H+H2, H+CH 4, OH+CH4 and H+C2H6 reactions. © 2012 Elsevier B.V. All rights reserved.

  9. Nucleophilic ring opening reactions of aziridines.

    Science.gov (United States)

    Akhtar, Rabia; Naqvi, Syed Ali Raza; Zahoor, Ameer Fawad; Saleem, Sameera

    2018-05-04

    Aziridine ring opening reactions have gained tremendous importance in the synthesis of nitrogen containing biologically active molecules. During recent years, a great effort has been put forward by scientists toward unique bond construction methodologies via ring opening of aziridines. In this regard, a wide range of chiral metal- and organo-catalyzed desymmetrization reactions of aziridines have been reported with carbon, sulfur, oxygen, nitrogen, halogen, and other nucleophiles. In this review, an outline of methodologies adopted by a number of scientists during 2013-2017 for aziridine ring opening reactions as well as their synthetic applications is described.

  10. Use of fluorine-18 free of carrier for the synthesis of 2-[{sup 18} F]-fluoro-2-deoxy-d-glucose by nucleophilic substitution; Uso del fluor-18 libre de portador para la sintesis de la 2-[{sup 18} F]-fluoro-2-deoxi-d-glucosa por sustitucion nucleofilica

    Energy Technology Data Exchange (ETDEWEB)

    Garcia S, I; Ramirez, F M

    1990-11-15

    Preliminary studies on the synthesis of 2 - [{sup 18} F]-fluoro-2-deoxy-d-glucose (2 - [{sup 18} F]-FDG) were carried out by means of the nucleophilic method proposed by K. Hamacher and the {sup 18} F obtained in the Nuclear Reactor TRIGA Mark III of the Nuclear Center of Mexico. For the control of radiochemical quality it was used the chromatography technique in paper and silica gel with 4 solvent systems. The identification of the marked species with {sup 18} F was carried out by means of comparison of its Rf with the Rf of the obtained not radioactive species, using the same synthesis method. (Author)

  11. Bimolecular reaction dynamics from photoelectron spectroscopy of negative ions

    Energy Technology Data Exchange (ETDEWEB)

    Bradforth, S.E.

    1992-11-01

    The transition state region of a neutral bimolecular reaction may be experimentally investigated by photoelectron spectroscopy of an appropriate negative ion. The photoelectron spectrum provides information on the spectroscopy and dynamics of the short lived transition state and may be used to develop model potential energy surfaces that are semi-quantitative in this important region. The principles of bound [yields] bound negative ion photoelectron spectroscopy are illustrated by way of an example: a full analysis of the photoelectron bands of CN[sup [minus

  12. Addition of HO-nucleophiles to free and coordinated nitriles

    International Nuclear Information System (INIS)

    Bokach, Nadejda A; Kukushkin, Vadim Yu

    2005-01-01

    The review surveys data on the addition of HO-nucleophiles (water, oximes, hydroxylamines, hydroxamic acids, alcohols) to nitriles. Main methods for C≡N bond activation in nucleophilic addition reactions are discussed. Particular attention is given to activation of nitriles through coordination to metal centres.

  13. An unprecedented chemospecific and stereoselective tandem nucleophilic addition/cycloaddition reaction of nucleophilic carbenes with ketenimines.

    Science.gov (United States)

    Cheng, Ying; Ma, Yang-Guang; Wang, Xiao-Rong; Mo, Jun-Ming

    2009-01-16

    The first study of the reaction between nucleophilic carbenes and ketenimines is reported. The interaction of thiazole and benzothiazole carbenes with ketenimines proceeded in a chemospecific and stereoselective manner to produce thiazole- and benzothiazole-spiro-pyrrole derivatives generally in good yields. The reaction was proposed to proceed via a tandem nucleophilic addition of carbene to the C=N bond of ketenimine followed by a stepwise [3+2] cycloaddition of the 1,3-dipolar intermediate with the C=C bond of ketenimine. This reaction provides a powerful protocol for the construction of novel polyfunctional thiazole-spiro-pyrrole or benzothiazole-spiro-pyrrole compounds that are not readily accessible by other methods.

  14. Olefination reactions of phosphorus-stabilized carbon nucleophiles.

    Science.gov (United States)

    Gu, Yonghong; Tian, Shi-Kai

    2012-01-01

    A range of phosphorus-stabilized carbon nucleophiles have been employed for alkene synthesis with high chemo-, regio-, and stereoselectivity. The Wittig, Horner-Wadsworth-Emmons, Horner-Wittig, and Evans-Akiba reactions utilize phosphonium-, phosphonate-, phosphine oxide-, and pentacoordinated phosphorane-stabilized carbanions as nucleophiles, respectively, to undergo olefination with aldehydes or ketones, and each of these transformations has its own advantages and limitations. Modifying the structures of these nucleophiles along with optimizing reaction conditions results in the formation of a wide variety of polysubstituted alkenes in a highly stereoselective manner. The olefination of imines with phosphonium ylides has recently emerged as a useful approach to tune the stereoselectivity for alkene synthesis. This review focuses on recent advances in the stereoselective olefination of phosphorus-stabilized carbon nucleophiles.

  15. Very Low Rate Constants of Bimolecular CO Adsorption on Anionic Gold Clusters: Implications for Catalytic Activity

    Czech Academy of Sciences Publication Activity Database

    Balteanu, I.; Balaj, O. P.; Fox, B. S.; Beyer, M. K.; Bastl, Zdeněk; Bondybey, V. E.

    2003-01-01

    Roč. 5, - (2003), s. 1213-1218 ISSN 1463-9076 Institutional research plan: CEZ:AV0Z4040901 Keywords : bimolecular * adsorption * catalytic activity Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.959, year: 2003

  16. Bimolecular reaction dynamics from photoelectron spectroscopy of negative ions

    Energy Technology Data Exchange (ETDEWEB)

    Bradforth, Stephen Edmund [Univ. of California, Berkeley, CA (United States)

    1992-11-01

    The transition state region of a neutral bimolecular reaction may be experimentally investigated by photoelectron spectroscopy of an appropriate negative ion. The photoelectron spectrum provides information on the spectroscopy and dynamics of the short lived transition state and may be used to develop model potential energy surfaces that are semi-quantitative in this important region. The principles of bound {yields} bound negative ion photoelectron spectroscopy are illustrated by way of an example: a full analysis of the photoelectron bands of CN-, NCO- and NCS-. Transition state photoelectron spectra are presented for the following systems Br + HI, Cl + HI, F + HI, F + CH30H,F + C2H5OH,F + OH and F + H2. A time dependent framework for the simulation and interpretation of the bound → free transition state photoelectron spectra is subsequently developed and applied to the hydrogen transfer reactions Br + HI, F + OH → O(3P, 1D) + HF and F + H2. The theoretical approach for the simulations is a fully quantum-mechanical wave packet propagation on a collinear model reaction potential surface. The connection between the wavepacket time evolution and the photoelectron spectrum is given by the time autocorrelation function. For the benchmark F + H2 system, comparisons with three-dimensional quantum calculations are made.

  17. Bimolecular reaction dynamics from photoelectron spectroscopy of negative ions

    International Nuclear Information System (INIS)

    Bradforth, S.E.

    1992-11-01

    The transition state region of a neutral bimolecular reaction may be experimentally investigated by photoelectron spectroscopy of an appropriate negative ion. The photoelectron spectrum provides information on the spectroscopy and dynamics of the short lived transition state and may be used to develop model potential energy surfaces that are semi-quantitative in this important region. The principles of bound → bound negative ion photoelectron spectroscopy are illustrated by way of an example: a full analysis of the photoelectron bands of CN - , NCO - and NCS - . Transition state photoelectron spectra are presented for the following systems Br + HI, Cl + HI, F + HI, F + CH 3 0H,F + C 2 H 5 OH,F + OH and F + H 2 . A time dependent framework for the simulation and interpretation of the bound → free transition state photoelectron spectra is subsequently developed and applied to the hydrogen transfer reactions Br + HI, F + OH → O( 3 P, 1 D) + HF and F + H 2 . The theoretical approach for the simulations is a fully quantum-mechanical wave packet propagation on a collinear model reaction potential surface. The connection between the wavepacket time evolution and the photoelectron spectrum is given by the time autocorrelation function. For the benchmark F + H 2 system, comparisons with three-dimensional quantum calculations are made

  18. Inversion of Configuration at the Phosphorus Nucleophile in the Diastereoselective and Enantioselective Synthesis of P-Stereogenic syn-Phosphiranes from Chiral Epoxides.

    Science.gov (United States)

    Muldoon, Jake A; Varga, Balázs R; Deegan, Meaghan M; Chapp, Timothy W; Eördögh, Ádám M; Hughes, Russell P; Glueck, David S; Moore, Curtis E; Rheingold, Arnold L

    2018-04-23

    Nucleophilic substitution results in inversion of configuration at the electrophilic carbon center (S N 2) or racemization (S N 1). The stereochemistry of the nucleophile is rarely considered, but phosphines, which have a high barrier to pyramidal inversion, attack electrophiles with retention of configuration at P. Surprisingly, cyclization of bifunctional secondary phosphine alkyl tosylates proceeded under mild conditions with inversion of configuration at the nucleophile to yield P-stereogenic syn-phosphiranes. DFT studies suggested that the novel stereochemistry results from acid-promoted tosylate dissociation to yield an intermediate phosphenium-bridged cation, which undergoes syn-selective cyclization. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Nucleophilic addition of amines to the activated ethylene bond in non-aqueous media

    International Nuclear Information System (INIS)

    Perepichka, Igor F.; Popov, Anatolii F.

    1995-01-01

    The kinetics of addition of a number of primary and secondary aliphatic amines to trans-(2-furyl) nitro ethylene (1) has been studied in solvents of various polarities (from acetonitrile, ε 37.5, to heptane, ε 1.89). It has been shown that the reaction is catalysed both by the amine reagent and by tertiary amines. On the basis of analyzing the observed kinetic regularities a stepwise reaction mechanism has been proposed which involves formation of zwitterionic intermediate (3) at the first equilibrium step (k 1 , K 1 ) which is then converted into the reaction product by means of proton transfer in parallel routes, the non-catalytic one (k 2 ) and that catalysed by the initial (K 3 ) or tertiary (K 4 ) amine. The observed high values of the deuterium isotope effects in the reaction (K H /K D ∼ 2.3 - 8.9) confirm that proton transfer occurs in the rate-limiting step of the reaction (primary kinetic isotope effect). The third order by amine kinetic route is observed in low polar media which is due to participation of amine dimers (R 2 NH HNR 2 ) in the reaction. The observed kinetic regularities are compared with those for the nucleophilic aromatic substitution reactions in low-polar media, and the conclusion has been made that the reaction route of the third order by amine proceeds as reversible nucleophilic attack by amine dimer and following base-catalysed transformation of the intermediate into the product. (author)

  20. The stereodynamics of photon-initiated bimolecular reactions

    International Nuclear Information System (INIS)

    Hughes, D.W.

    1999-01-01

    This thesis concerns the stereodynamics of the product state resolved reaction: H( 2 S) + CO 2 → (HOCO) → OH(X 2 Π Ω ; v, N, f) + CO( 1 Σ + ). Translationally excited hydrogen atoms were generated from HBr and HCl precursor molecules, via polarised laser photolysis, and the Doppler lineshapes of nascent OH products were monitored using polarised laser radiation. Four different OH product channels were investigated at a collision energy of 2.5 eV, and two OH product channels were studied at a collision energy of 1.8 eV. Three main sources of product state specific information were recovered from the Doppler profiles: Differential cross-sections (DCS); Product translational energy distributions (P(f)); Product rotational angular momentum distributions. Product state specific differential cross-sections (generated through collisions at 2.5 eV) suggest that OH( 2 Π 1/2 ) products may be produced through a more 'direct' route than OH( 2 Π 3/2 ) products. Differential cross-sections recorded for OH products generated through collisions at 1.8 eV, however, imply that neither OH spin-orbit state is populated through a 'direct' mechanism. The P(f t ) distributions for all OH product channels exhibit more product translational excitation than would be expected on the basis of phase space theory. This may imply either that the lifetimes of the collision complexes are short with respect to the timescale for intramolecular internal energy randomisation, or that there are significant exit channel interactions. The polarisation of the OH rotational angular momentum distribution is seen to be highly sensitive to the rotational and spin-orbit state of the OH products, but less sensitive to the collision energy and lambda-doublet state of the OH product. This thesis outlines the scope of present day experimental stereodynamical studies of gas-phase reactions (chapter 1), the theory of vector correlations in photoninitiated bimolecular reactions (chapter 2) and the

  1. Photoinduced bimolecular electron transfer kinetics in small unilamellar vesicles

    International Nuclear Information System (INIS)

    Choudhury, Sharmistha Dutta; Kumbhakar, Manoj; Nath, Sukhendu; Pal, Haridas

    2007-01-01

    Photoinduced electron transfer (ET) from N,N-dimethylaniline to some coumarin derivatives has been studied in small unilamellar vesicles (SUVs) of the phospholipid, DL-α-dimyristoyl-phosphatidylcholine, using steady-state and time-resolved fluorescence quenching, both below and above the phase transition temperature of the vesicles. The primary interest was to examine whether Marcus inversion [H. Sumi and R. A. Marcus, J. Chem. Phys. 84, 4894 (1986)] could be observed for the present ET systems in these organized assemblies. The influence of the topology of SUVs on the photophysical properties of the reactants and consequently on their ET kinetics has also been investigated. Absorption and fluorescence spectral data of the coumarins in SUVs and the variation of their fluorescence decays with temperature indicate that the dyes are localized in the bilayer of the SUVs. Time-resolved area normalized emission spectra analysis, however, reveals that the dyes are distributed in two different microenvironments in the SUVs, which we attribute to the two leaflets of the bilayer, one toward bulk water and the other toward the inner water pool. The microenvironments in the two leaflets are, however, not indicated to be that significantly different. Time-resolved anisotropy decays were biexponential for all the dyes in SUVs, and this has been interpreted in terms of the compound motion model according to which the dye molecules can experience a fast wobbling-in-cone type of motion as well as a slow overall rotating motion of the cone containing the molecule. The expected bimolecular diffusion-controlled rates in SUVs, as estimated by comparing the microviscosities in SUVs (determined from rotational correlation times) and that in acetonitrile solution, are much slower than the observed fluorescence quenching rates, suggesting that reactant diffusion (translational) does not play any role in the quenching kinetics in the present systems. Accordingly, clear inversions are

  2. Ring transformation of chromone-3-carboxamide under nucleophilic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, Magdy A., E-mail: magdy_ahmed1977@yahoo.com [Department of Chemistry, Faculty of Education, Ain Shams University, Cairo(Egypt)

    2013-11-15

    The chemical reactivity of chromone-3-carboxamide was studied towards a series of nitrogen and carbon nucleophiles. Treatment of carboxamide with some primary amines gave chromane-2,4-diones. Condensation of carboxamide with hydrazine hydrate, phenyl hydrazine and hydroxylamine hydrochloride afforded chromenopyrazoles and chromenoisoxazole, respectively. Reaction of carboxamide with guanidine hydrochloride, cyanoguanidine and thiourea resulted in ring transformation producing chromenopyridines. The chemical behavior of carboxamide was also studied towards ethylenediamine, o-phenylenediamine, 2-aminophenol and 2-aminothiophenol. A variety of products were isolated from the reaction of carboxamide with some carbon nucleophiles. (author)

  3. Highly Defined Multiblock Copolypeptoids: Pushing the Limits of Living Nucleophilic Ring-Opening Polymerization

    KAUST Repository

    Fetsch, Corinna

    2012-06-05

    Advanced macromolecular engineering requires excellent control over the polymerization reaction. Living polymerization methods are notoriously sensitive to impurities, which makes a practical realization of such control very challenging. Reversible-deactivation radical polymerization methods are typically more robust, but have other limitations. Here, we demonstrate by repeated (ge;10 times) chain extension the extraordinary robustness of the living nucleophilic ring-opening polymerization of N-substituted glycine N-carboxyanhydrides, which yields polypeptoids. We observe essentially quantitative end-group fidelity under experimental conditions that are comparatively easily managed. This is employed to synthesize a pentablock quinquiespolymer with high definition. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Highly Defined Multiblock Copolypeptoids: Pushing the Limits of Living Nucleophilic Ring-Opening Polymerization

    KAUST Repository

    Fetsch, Corinna; Luxenhofer, Robert

    2012-01-01

    Advanced macromolecular engineering requires excellent control over the polymerization reaction. Living polymerization methods are notoriously sensitive to impurities, which makes a practical realization of such control very challenging. Reversible-deactivation radical polymerization methods are typically more robust, but have other limitations. Here, we demonstrate by repeated (ge;10 times) chain extension the extraordinary robustness of the living nucleophilic ring-opening polymerization of N-substituted glycine N-carboxyanhydrides, which yields polypeptoids. We observe essentially quantitative end-group fidelity under experimental conditions that are comparatively easily managed. This is employed to synthesize a pentablock quinquiespolymer with high definition. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Alkoxide-induced nucleophilic trifluoromethylation using diethyl trifluoromethylphosphonate

    Czech Academy of Sciences Publication Activity Database

    Cherkupally, Prabhakar; Beier, Petr

    2010-01-01

    Roč. 51, č. 2 (2010), s. 252-255 ISSN 0040-4039 R&D Projects: GA ČR GP203/08/P310 Institutional research plan: CEZ:AV0Z40550506 Keywords : trifluoromethylation * phosphonate * nucleophilic addition Subject RIV: CC - Organic Chemistry Impact factor: 2.618, year: 2010

  6. Diethyl Fluoronitromethylphosphonate: Synthesis and Application in Nucleophilic Fluoroalkyl Additions

    Czech Academy of Sciences Publication Activity Database

    Opekar, Stanislav; Pohl, Radek; Beran, Pavel; Rulíšek, Lubomír; Beier, Petr

    2014-01-01

    Roč. 20, č. 5 (2014), s. 1453-1458 ISSN 0947-6539 R&D Projects: GA ČR GP203/08/P310 Institutional support: RVO:61388963 Keywords : C1 building blocks * fluorine * nucleophilic addition * phosphanes * synthetic methods Subject RIV: CC - Organic Chemistry Impact factor: 5.731, year: 2014

  7. Tandem Cu-catalyzed ketenimine formation and intramolecular nucleophile capture: Synthesis of 1,2-dihydro-2-iminoquinolines from 1-(o-acetamidophenyl)propargyl alcohols

    Science.gov (United States)

    Kant, Ruchir

    2014-01-01

    Summary The copper-catalyzed ketenimine formation reaction of 1-(o-acetamidophenyl)propargyl alcohols with various sulfonyl azides is found to undergo a concomitant intramolecular nucleophile attack to generate 1,2-dihydro-2-iminoquinolines after aromatization (via elimination of acetyl and hydroxy groups) and tautomerization. The reaction produces 4-substituted and 3,4-unsubstituted title compounds in moderate to good yields under mild reaction conditions. PMID:24991276

  8. Nucleophilic tetrafluoroethylation of carbonyl compounds with fluorinated sulfones

    Czech Academy of Sciences Publication Activity Database

    Václavík, Jiří; Chernykh, Yana; Jurásek, Bronislav; Beier, Petr

    2015-01-01

    Roč. 169, Jan (2015), s. 24-31 ISSN 0022-1139 R&D Projects: GA ČR GAP207/11/0421 Grant - others:GA MŠk(CZ) ED3.2.00/08.0144; GA MŠk(CZ) LM2010005 Institutional support: RVO:61388963 Keywords : fluorine * tetrafluoroethylation * sulfones * nucleophilic addition * carbonyl compounds Subject RIV: CC - Organic Chemistry Impact factor: 2.213, year: 2015

  9. General Allylic C–H Alkylation with Tertiary Nucleophiles

    Science.gov (United States)

    2015-01-01

    A general method for intermolecular allylic C–H alkylation of terminal olefins with tertiary nucleophiles has been accomplished employing palladium(II)/bis(sulfoxide) catalysis. Allylic C–H alkylation furnishes products in good yields (avg. 64%) with excellent regio- and stereoselectivity (>20:1 linear:branched, >20:1 E:Z). For the first time, the olefin scope encompasses unactivated aliphatic olefins as well as activated aromatic/heteroaromatic olefins and 1,4-dienes. The ease of appending allyl moieties onto complex scaffolds is leveraged to enable this mild and selective allylic C–H alkylation to rapidly diversify phenolic natural products. The tertiary nucleophile scope is broad and includes latent functionality for further elaboration (e.g., aliphatic alcohols, α,β-unsaturated esters). The opportunities to effect synthetic streamlining with such general C–H reactivity are illustrated in an allylic C–H alkylation/Diels–Alder reaction cascade: a reactive diene is generated via intermolecular allylic C–H alkylation and approximated to a dienophile contained within the tertiary nucleophile to furnish a common tricyclic core found in the class I galbulimima alkaloids. PMID:24641574

  10. General allylic C-H alkylation with tertiary nucleophiles.

    Science.gov (United States)

    Howell, Jennifer M; Liu, Wei; Young, Andrew J; White, M Christina

    2014-04-16

    A general method for intermolecular allylic C-H alkylation of terminal olefins with tertiary nucleophiles has been accomplished employing palladium(II)/bis(sulfoxide) catalysis. Allylic C-H alkylation furnishes products in good yields (avg. 64%) with excellent regio- and stereoselectivity (>20:1 linear:branched, >20:1 E:Z). For the first time, the olefin scope encompasses unactivated aliphatic olefins as well as activated aromatic/heteroaromatic olefins and 1,4-dienes. The ease of appending allyl moieties onto complex scaffolds is leveraged to enable this mild and selective allylic C-H alkylation to rapidly diversify phenolic natural products. The tertiary nucleophile scope is broad and includes latent functionality for further elaboration (e.g., aliphatic alcohols, α,β-unsaturated esters). The opportunities to effect synthetic streamlining with such general C-H reactivity are illustrated in an allylic C-H alkylation/Diels-Alder reaction cascade: a reactive diene is generated via intermolecular allylic C-H alkylation and approximated to a dienophile contained within the tertiary nucleophile to furnish a common tricyclic core found in the class I galbulimima alkaloids.

  11. Uncertainty for calculating transport on Titan: A probabilistic description of bimolecular diffusion parameters

    Science.gov (United States)

    Plessis, S.; McDougall, D.; Mandt, K.; Greathouse, T.; Luspay-Kuti, A.

    2015-11-01

    Bimolecular diffusion coefficients are important parameters used by atmospheric models to calculate altitude profiles of minor constituents in an atmosphere. Unfortunately, laboratory measurements of these coefficients were never conducted at temperature conditions relevant to the atmosphere of Titan. Here we conduct a detailed uncertainty analysis of the bimolecular diffusion coefficient parameters as applied to Titan's upper atmosphere to provide a better understanding of the impact of uncertainty for this parameter on models. Because temperature and pressure conditions are much lower than the laboratory conditions in which bimolecular diffusion parameters were measured, we apply a Bayesian framework, a problem-agnostic framework, to determine parameter estimates and associated uncertainties. We solve the Bayesian calibration problem using the open-source QUESO library which also performs a propagation of uncertainties in the calibrated parameters to temperature and pressure conditions observed in Titan's upper atmosphere. Our results show that, after propagating uncertainty through the Massman model, the uncertainty in molecular diffusion is highly correlated to temperature and we observe no noticeable correlation with pressure. We propagate the calibrated molecular diffusion estimate and associated uncertainty to obtain an estimate with uncertainty due to bimolecular diffusion for the methane molar fraction as a function of altitude. Results show that the uncertainty in methane abundance due to molecular diffusion is in general small compared to eddy diffusion and the chemical kinetics description. However, methane abundance is most sensitive to uncertainty in molecular diffusion above 1200 km where the errors are nontrivial and could have important implications for scientific research based on diffusion models in this altitude range.

  12. Hydroxylamine as an oxygen nucleophile: substitution of sulfonamide by a hydroxyl group in benzothiazole-2-sulfonamides

    NARCIS (Netherlands)

    Kamps, J.A.G.; Belle, R.; Mecinovic, J.

    2013-01-01

    Benzothiazole-2-sulfonamides react with an excess of hydroxylamine in aqueous solutions to form 2-hydroxybenzothiazole, sulfur dioxide, and the corresponding amine. Mechanistic studies that employ a combination of structure-reactivity relationships, oxygen labeling experiments, and (in)direct

  13. Validated spectrophotometric methods for determination of Alendronate sodium in tablets through nucleophilic aromatic substitution reactions

    Directory of Open Access Journals (Sweden)

    Walash Mohamed I

    2012-04-01

    Full Text Available Abstract Background Alendronate (ALD is a member of the bisphosphonate family which is used for the treatment of osteoporosis, bone metastasis, Paget's disease, hypocalcaemia associated with malignancy and other conditions that feature bone fragility. ALD is a non-chromophoric compound so its determination by conventional spectrophotometric methods is not possible. So two derivatization reactions were proposed for determination of ALD through the reaction with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl and 2,4-dinitrofluorobenzene (DNFB as chromogenic derivatizing reagents. Results Three simple and sensitive spectrophotometric methods are described for the determination of ALD. Method I is based on the reaction of ALD with NBD-Cl. Method II involved heat-catalyzed derivatization of ALD with DNFB, while, Method III is based on micellar-catalyzed reaction of the studied drug with DNFB at room temperature. The reactions products were measured at 472, 378 and 374 nm, for methods I, II and III, respectively. Beer's law was obeyed over the concentration ranges of 1.0-20.0, 4.0-40.0 and 1.5-30.0 μg/mL with lower limits of detection of 0.09, 1.06 and 0.06 μg/mL for Methods I, II and III, respectively. The proposed methods were applied for quantitation of the studied drug in its pure form with mean percentage recoveries of 100.47 ± 1.12, 100.17 ± 1.21 and 99.23 ± 1.26 for Methods I, II and III, respectively. Moreover the proposed methods were successfully applied for determination of ALD in different tablets. Proposals of the reactions pathways have been postulated. Conclusion The proposed spectrophotometric methods provided sensitive, specific and inexpensive analytical procedures for determination of the non-chromophoric drug alendronate either per se or in its tablet dosage forms without interference from common excipients. Graphical abstract

  14. A General Catalytic Method for Highly Cost- and Atom-Efficient Nucleophilic Substitutions.

    Science.gov (United States)

    Huy, Peter H; Filbrich, Isabel

    2018-05-23

    A general formamide-catalyzed protocol for the efficient transformation of alcohols into alkyl chlorides, which is promoted by substoichiometric amounts (down to 34 mol %) of inexpensive trichlorotriazine (TCT), is introduced. This is the first example of a TCT-mediated dihydroxychlorination of an OH-containing substrate (e.g., alcohols and carboxylic acids) in which all three chlorine atoms of TCT are transferred to the starting material. The consequently enhanced atom economy facilitates a significantly improved waste balance (E-factors down to 4), cost efficiency, and scalability (>50 g). Furthermore, the current procedure is distinguished by high levels of functional-group compatibility and stereoselectivity, as only weakly acidic cyanuric acid is released as exclusive byproduct. Finally, a one-pot protocol for the preparation of amines, azides, ethers, and sulfides enabled the synthesis of the drug rivastigmine with twofold S N 2 inversion, which demonstrates the high practical value of the presented method. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Concentrated Aqueous Sodium Tosylate as Green Medium for Alkene Oxidation and Nucleophilic Substitution Reactions.

    Science.gov (United States)

    Sela, Tal; Lin, Xiaoxi; Vigalok, Arkadi

    2017-11-03

    A hydrotropic solution of highly concentrated sodium tosylate (NaOTs) can be used as a recyclable medium for the environmentally benign oxidation of conjugated alkenes with H 2 O 2 . Both uncatalyzed and metal-catalyzed reactions provided the corresponding oxidation products in higher yields than in pure water or many common organic solvents.

  16. Nucleophilic Substitution and Redox Reactions with alpha-Chloro beta-Oxo Sulfenyl Chlorides

    DEFF Research Database (Denmark)

    El-Essawy, Farag A.G.; Yassin, Salah M.; El-Sakka, Ibrahim A.

    1998-01-01

    Alpha-Chloro sulfenyl chlorides such as 1 and 4 could not be reduced to the corresponding disulfides. Under reducing conditions they are instead dechlorinated to the corresponding thiocarbonyl compounds. Starting from the chroman-4-one derivatives 1 a number of 1,3,4-oxadithiins 3 have been prepa...

  17. Inhomogeneous bimolecular recombination in partially crystallised tri-methylphenyl diamine glasses

    International Nuclear Information System (INIS)

    Goldie, D.M.

    2013-01-01

    The rise and fall dynamics of transient photocurrents induced by exposure to ultraviolet radiation have been analysed for a series of glassy tri-methylphenyl diamine films that have been partially crystallised by ageing under ambient conditions following vapour deposition. An inhomogeneous bimolecular recombination model that uses coupled rate equations is found to provide a consistent fit for the observed photocurrent dynamics provided the recombination rate of holes in the crystallised regions of the films is lower compared to the amorphous regions. Parameters returned by the bimolecular model are investigated as a function of the film age but are observed to be highly sensitive to the initial experimental estimates that are supplied for the effective hole recombination time. The effective hole recombination time generated by the model is found to be relatively independent of film age, however, and has a value of around 0.16 s for a carrier generation rate of 7 × 10 14 cm −3 s −1 . The effective recombination time and steady-state photoconductivity magnitudes are found to be consistent with experimental hole mobility and photo-carrier generation efficiency values that are obtained using complementary time-of-flight and charge collection experiments. - Highlights: ► Transient photocurrents in evaporated diamine films have fast and slow components. ► Transient photocurrents are modelled using inhomogeneous bimolecular recombination. ► Recombination rates differ between crystallised and amorphous film regions. ► Recombination parameters evolve with film age as the films crystallise

  18. Synthesis of substituted gamma-lactams through petasis-type addition of boronic acids to N-acyliminium lons

    DEFF Research Database (Denmark)

    Wu, Peng; Clausen, Mads Hartvig; Nielsen, Thomas Eiland

    2014-01-01

    Substituted g -lactams are important heterocyclic motifs found in various biologically active compounds and marketed drugs, such as glimepiride, doxapram, and levetiracetam. Among available m ethods for the synthesis of substituted g -lactams, the addition of nucleophiles to N -acyliminium ions...

  19. Multiple nucleophilic elbows leading to multiple active sites in a single module esterase from Sorangium cellulosum

    DEFF Research Database (Denmark)

    Udatha, D.B.R.K. Gupta; Madsen, Karina Marie; Panagiotou, Gianni

    2015-01-01

    The catalytic residues in carbohydrate esterase enzyme families constitute a highly conserved triad: serine, histidine and aspartic acid. This catalytic triad is generally located in a very sharp turn of the protein backbone structure, called the nucleophilic elbow and identified by the consensus...... sequence GXSXG. An esterase from Sorangium cellulosum Soce56 that contains five nucleophilic elbows was cloned and expressed in Escherichia coli and the function of each nucleophilic elbowed site was characterized. In order to elucidate the function of each nucleophilic elbow, site directed mutagenesis....... To our knowledge, this is the first report presenting the role of multiple nucleophilic elbows in the catalytic promiscuity of an esterase. Further structural analysis at protein unit level indicates the new evolutionary trajectories in emerging promiscuous esterases....

  20. Turing instability and bifurcation analysis in a diffusive bimolecular system with delayed feedback

    Science.gov (United States)

    Wei, Xin; Wei, Junjie

    2017-09-01

    A diffusive autocatalytic bimolecular model with delayed feedback subject to Neumann boundary conditions is considered. We mainly study the stability of the unique positive equilibrium and the existence of periodic solutions. Our study shows that diffusion can give rise to Turing instability, and the time delay can affect the stability of the positive equilibrium and result in the occurrence of Hopf bifurcations. By applying the normal form theory and center manifold reduction for partial functional differential equations, we investigate the stability and direction of the bifurcations. Finally, we give some simulations to illustrate our theoretical results.

  1. Stereochemistry of substitution at trico-ordinate phosphorus

    DEFF Research Database (Denmark)

    Nielsen, John; Dahl, Otto

    1984-01-01

    A series of reactions of ring-substituted 1,3,2-dioxaphospholanes, 1,3,2-oxazaphospholanes, 1,2-oxaphospholes, and phosphetanes bearing the leaving groups Cl, OR, or NR2 on phosphorus, with the nucleophiles HCl, MeO-, MeOH, PhOH, Me2NH, Et2NH, and [CH 2]5NH have been studied. N.m.r. signals (1H...

  2. Modeling Bimolecular Reactive Transport With Mixing-Limitation: Theory and Application to Column Experiments

    Science.gov (United States)

    Ginn, T. R.

    2018-01-01

    The challenge of determining mixing extent of solutions undergoing advective-dispersive-diffusive transport is well known. In particular, reaction extent between displacing and displaced solutes depends on mixing at the pore scale, that is, generally smaller than continuum scale quantification that relies on dispersive fluxes. Here a novel mobile-mobile mass transfer approach is developed to distinguish diffusive mixing from dispersive spreading in one-dimensional transport involving small-scale velocity variations with some correlation, such as occurs in hydrodynamic dispersion, in which short-range ballistic transports give rise to dispersed but not mixed segregation zones, termed here ballisticules. When considering transport of a single solution, this approach distinguishes self-diffusive mixing from spreading, and in the case of displacement of one solution by another, each containing a participant reactant of an irreversible bimolecular reaction, this results in time-delayed diffusive mixing of reactants. The approach generates models for both kinetically controlled and equilibrium irreversible reaction cases, while honoring independently measured reaction rates and dispersivities. The mathematical solution for the equilibrium case is a simple analytical expression. The approach is applied to published experimental data on bimolecular reactions for homogeneous porous media under postasymptotic dispersive conditions with good results.

  3. Effects of geminate and bimolecular recombination on the performance of polymeric-small molecular solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Schubert, Marcel; Yin, Chunhong; Castellani, Mauro; Neher, Dieter [University of Potsdam, Institute of Physics and Astronomy, 14476 Potsdam-Golm (Germany); Sellinger, Alan [IMRE, 3 Research Link, 117602 Singapore (Singapore)

    2009-07-01

    Many physical properties of organic photovoltaics are related to the nature of the geminate pair, an intermediate state that forms after dissociation of photogenerated excitons and prior to free charge carrier generation. Whereas it was found that photocurrent generation is dominated by the strong field dependent process of geminate pair dissociation, the recombination of uncorrelated free charge carriers and the formation of space charge seem to play a minor role in the prominent P3HT/PCBM combination. The situation may change, when using different D/A combinations or other soluble acceptor molecules. We present organic solar cells comprising a novel small molecule based on 2-vinyl-4,5-dicyanoimidazole (Vinazene) as acceptor and M3EH-PPV as donor. While bilayer devices show promising results with a fill factor up to 57 %, the IU-characteristics of bulk heterojunction devices are dominated by bimolecular recombination and space charge effects even at moderate illumination intensities. Photo-CELIV measurements were performed to study the bimolecular recombination in detail. By combining photo-CELIV results with PL and IU measurements we are able to analyze the interrelation of recombination losses, free charge carrier generation and exciplex formation.

  4. Bimolecular Master Equations for a Single and Multiple Potential Wells with Analytic Solutions.

    Science.gov (United States)

    Ghaderi, Nima

    2018-04-12

    The analytic solutions, that is, populations, are derived for the K-adiabatic and K-active bimolecular master equations, separately, for a single and multiple potential wells and reaction channels, where K is the component of the total angular momentum J along the axis of least moment of inertia of the recombination products at a given energy E. The analytic approach provides the functional dependence of the population of molecules on its K-active or K-adiabatic dissociation, association rate constants and the intermolecular energy transfer, where the approach may complement the usual numerical approaches for reactions of interest. Our previous work, Part I, considered the solutions for a single potential well, whereby an assumption utilized there is presently obviated in the derivation of the exact solutions and farther discussed. At the high-pressure limit, the K-adiabatic and K-active bimolecular master equations may each reduce, respectively, to the K-adiabatic and K-active bimolecular Rice-Ramsperger-Kassel-Marcus theory (high-pressure limit expressions) for bimolecular recombination rate constant, for a single potential well, and augmented by isomerization terms when multiple potential wells are present. In the low-pressure limit, the expression for population above the dissociation limit, associated with a single potential well, becomes equivalent to the usual presumed detailed balance between the association and dissociation rate constants, where the multiple well case is also considered. When the collision frequency of energy transfer, Z LJ , between the chemical intermediate and bath gas is sufficiently less than the dissociation rate constant k d ( E' J' K') for postcollision ( E' J' K), then the solution for population, g( EJK) + , above the critical energy further simplifies such that depending on Z LJ , the dissociation and association rate constant k r ( EJK), as g( EJK) + = k r ( EJK)A·BC/[ Z LJ + k d ( EJK)], where A and BC are the reactants, for

  5. Substitutional analysis

    CERN Document Server

    Rutherford, Daniel Edwin

    2013-01-01

    Classic monograph, suitable for advanced undergraduates and graduate students. Topics include calculus of permutations and tableaux, semi-normal representation, orthogonal and natural representations, group characters, and substitutional equations. 1968 edition.

  6. Reactions of aromatic diazonium salts with unsaturated compounds in the presence of nucleophiles

    Science.gov (United States)

    Grishchuk, B. D.; Gorbovoi, P. M.; Ganushchak, N. I.; Dombrovskii, A. V.

    1994-03-01

    The review surveys the reactions of aromatic diazonium salts with diene and monounsaturated compounds in the presence of nucleophiles. Certain further reactions of the reaction products and their application are considered. The bibliography includes 63 references.

  7. Chemoselective reductive nucleophilic addition to tertiary amides, secondary amides, and N-methoxyamides.

    Science.gov (United States)

    Nakajima, Minami; Oda, Yukiko; Wada, Takamasa; Minamikawa, Ryo; Shirokane, Kenji; Sato, Takaaki; Chida, Noritaka

    2014-12-22

    As the complexity of targeted molecules increases in modern organic synthesis, chemoselectivity is recognized as an important factor in the development of new methodologies. Chemoselective nucleophilic addition to amide carbonyl centers is a challenge because classical methods require harsh reaction conditions to overcome the poor electrophilicity of the amide carbonyl group. We have successfully developed a reductive nucleophilic addition of mild nucleophiles to tertiary amides, secondary amides, and N-methoxyamides that uses the Schwartz reagent [Cp2 ZrHCl]. The reaction took place in a highly chemoselective fashion in the presence of a variety of sensitive functional groups, such as methyl esters, which conventionally require protection prior to nucleophilic addition. The reaction will be applicable to the concise synthesis of complex natural alkaloids from readily available amide groups. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Vibrational transitions in hydrogen bonded bimolecular complexes – A local mode perturbation theory approach to transition frequencies and intensities

    DEFF Research Database (Denmark)

    Mackeprang, Kasper; Kjærgaard, Henrik Grum

    2017-01-01

    The local mode perturbation theory (LMPT) model was developed to improve the description of hydrogen bonded XH-stretching transitions, where X is typically O or N. We present a modified version of the LMPT model to extend its application from hydrated bimolecular complexes to hydrogen bonded...

  9. Platinum Catalyzed Ring-Opening of 1,2-Cyclopropanated Sugars with O-Nucleophiles

    DEFF Research Database (Denmark)

    Beyer, Jürgen; Skaanderup, Philip Robert; Madsen, Robert

    1999-01-01

    In the presence of a catalytic amount of Zeise's dimer 1,2-cyclopropanated sugars undergo regioselective ring-opening at C-1 with O-nucleophiles including alcohols, phenols and water to produce 2-C-branched carbohydrates.......In the presence of a catalytic amount of Zeise's dimer 1,2-cyclopropanated sugars undergo regioselective ring-opening at C-1 with O-nucleophiles including alcohols, phenols and water to produce 2-C-branched carbohydrates....

  10. Operator substitution

    NARCIS (Netherlands)

    Hautus, M.L.J.

    1994-01-01

    Substitution of an operator into an operator-valued map is defined and studied. A Bezout-type remainder theorem is used to derive a number of results. The tensor map is used to formulate solvability conditions for linear matrix equations. Some applications to system theory are given, in particular

  11. Solvent substitution

    International Nuclear Information System (INIS)

    1990-01-01

    The DOE Environmental Restoration and Waste Management Office of Technology Development and the Air Force Engineering and Services Center convened the First Annual International Workshop on Solvent Substitution on December 4--7, 1990. The primary objectives of this joint effort were to share information and ideas among attendees in order to enhance the development and implementation of required new technologies for the elimination of pollutants associated with industrial use of hazardous and toxic solvents; and to aid in accelerating collaborative efforts and technology transfer between government and industry for solvent substitution. There were workshop sessions focusing on Alternative Technologies, Alternative Solvents, Recovery/Recycling, Low VOC Materials and Treatment for Environmentally Safe Disposal. The 35 invited papers presented covered a wide range of solvent substitution activities including: hardware and weapons production and maintenance, paint stripping, coating applications, printed circuit boards, metal cleaning, metal finishing, manufacturing, compliance monitoring and process control monitoring. This publication includes the majority of these presentations. In addition, in order to further facilitate information exchange and technology transfer, the US Air Force and DOE solicited additional papers under a general ''Call for Papers.'' These papers, which underwent review and final selection by a peer review committee, are also included in this combined Proceedings/Compendium. For those involved in handling, using or managing hazardous and toxic solvents, this document should prove to be a valuable resource, providing the most up-to-date information on current technologies and practices in solvent substitution. Individual papers are abstracted separated

  12. Tonemic Substitution

    African Journals Online (AJOL)

    Ezenwafor

    grammatical constructions. The choice of substitutable tonemes as observed from the analyzed data is highly. Ezenwafordependent on the intuitive judgement of the native speaker. This work shows with adequate data, that regular tonemic changes are not always meaningful in Ekwulobia lect. Such tonemic alternations are ...

  13. Solvent substitution

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    The DOE Environmental Restoration and Waste Management Office of Technology Development and the Air Force Engineering and Services Center convened the First Annual International Workshop on Solvent Substitution on December 4--7, 1990. The primary objectives of this joint effort were to share information and ideas among attendees in order to enhance the development and implementation of required new technologies for the elimination of pollutants associated with industrial use of hazardous and toxic solvents; and to aid in accelerating collaborative efforts and technology transfer between government and industry for solvent substitution. There were workshop sessions focusing on Alternative Technologies, Alternative Solvents, Recovery/Recycling, Low VOC Materials and Treatment for Environmentally Safe Disposal. The 35 invited papers presented covered a wide range of solvent substitution activities including: hardware and weapons production and maintenance, paint stripping, coating applications, printed circuit boards, metal cleaning, metal finishing, manufacturing, compliance monitoring and process control monitoring. This publication includes the majority of these presentations. In addition, in order to further facilitate information exchange and technology transfer, the US Air Force and DOE solicited additional papers under a general Call for Papers.'' These papers, which underwent review and final selection by a peer review committee, are also included in this combined Proceedings/Compendium. For those involved in handling, using or managing hazardous and toxic solvents, this document should prove to be a valuable resource, providing the most up-to-date information on current technologies and practices in solvent substitution. Individual papers are abstracted separated.

  14. Identification of ortho-Substituted Benzoic Acid/Ester Derivatives via the Gas-Phase Neighboring Group Participation Effect in (+)-ESI High Resolution Mass Spectrometry.

    Science.gov (United States)

    Blincoe, William D; Rodriguez-Granillo, Agustina; Saurí, Josep; Pierson, Nicholas A; Joyce, Leo A; Mangion, Ian; Sheng, Huaming

    2018-04-01

    Benzoic acid/ester/amide derivatives are common moieties in pharmaceutical compounds and present a challenge in positional isomer identification by traditional tandem mass spectrometric analysis. A method is presented for exploiting the gas-phase neighboring group participation (NGP) effect to differentiate ortho-substituted benzoic acid/ester derivatives with high resolution mass spectrometry (HRMS 1 ). Significant water/alcohol loss (>30% abundance in MS 1 spectra) was observed for ortho-substituted nucleophilic groups; these fragment peaks are not observable for the corresponding para and meta-substituted analogs. Experiments were also extended to the analysis of two intermediates in the synthesis of suvorexant (Belsomra) with additional analysis conducted with nuclear magnetic resonance (NMR), density functional theory (DFT), and ion mobility spectrometry-mass spectrometry (IMS-MS) studies. Significant water/alcohol loss was also observed for 1-substituted 1, 2, 3-triazoles but not for the isomeric 2-substituted 1, 2, 3-triazole analogs. IMS-MS, NMR, and DFT studies were conducted to show that the preferred orientation of the 2-substituted triazole rotamer was away from the electrophilic center of the reaction, whereas the 1-subtituted triazole was oriented in close proximity to the center. Abundance of NGP product was determined to be a product of three factors: (1) proton affinity of the nucleophilic group; (2) steric impact of the nucleophile; and (3) proximity of the nucleophile to carboxylic acid/ester functional groups. Graphical Abstract ᅟ.

  15. Molecular-weight-enlarged multiple-pincer ligands: synthesis and application in palladium-catalyzed allylic substitution reactions

    NARCIS (Netherlands)

    Ronde, N.J.; Totev, D.; Müller, Christian; Lutz, M.; Spek, A.L.; Vogt, D.

    2009-01-01

    Three different pincer ligand systems are synthesized via nucleophilic substitution reactions of polyaromatic benzyl bromides as support molecules and phenol derivatives as ligand precursors. Retention tests using a polymeric nanofiltration membrane show moderate to good retention in THF and CH2Cl2.

  16. Kinetics on the reaction of substituted quinolines and p-substituted benzoylchlorides under various pressures

    International Nuclear Information System (INIS)

    Kim, Young Cheul; Lim, Jong Wan; Choi, Sung Yong; Kim, Se Kyong

    1999-01-01

    The reaction rates of substituted quinolines(6-CH 3 C 9 H 7 N, C 9 H 7 N) with p-substituted benzoylchlorides(p-CH 3 , p-H, p-NO 2 ) have been measured by conductometry in acetonitrile, and the rate constants are determined at various temperatures (10,15, 20, 25 .deg. C) and pressures(1, 200, 500, 1000bar). From the values of rate constants, the activation parameters(Ea, ΔV ≠ , ΔS ≠ , and ΔG ≠ ) and the pressure dependence of Hammett ρ values were determined. The rate constants increase as a function of temperatures and pressures, and are further increase by introduction the electron donor substituents in nucleophile(p-CH 3 ) or electron acceptor(p-NO 2 ) substituents in substrate. The activation volume, and the activation entropy are all negative. Hammett ρ values are also negative for nucleophile (ρ X ) and positive for the substrate (ρ Y ) over the pressure range studied. The results of kinetic studies for pressure and substituent show that these reactions proceed in typical S N 2 reaction mechanism and 'associative S N 2' in which bond formation favored with increasing pressures

  17. Interactions among the early Escherichia coli divisome proteins revealed by bimolecular fluorescence complementation.

    Science.gov (United States)

    Pazos, Manuel; Natale, Paolo; Margolin, William; Vicente, Miguel

    2013-12-01

    We used bimolecular fluorescence complementation (BiFC) assays to detect protein-protein interactions of all possible pairs of the essential Escherichia coli proto-ring components, FtsZ, FtsA and ZipA, as well as the non-essential FtsZ-associated proteins ZapA and ZapB. We found an unexpected interaction between ZipA and ZapB at potential cell division sites, and when co-overproduced, they induced long narrow constrictions at division sites that were dependent on FtsZ. These assays also uncovered an interaction between ZipA and ZapA that was mediated by FtsZ. BiFC with ZapA and ZapB showed that in addition to their expected interaction at midcell, they also interact at the cell poles. BiFC detected interaction between FtsZ and ZapB at midcell and close to the poles. Results from the remaining pairwise combinations confirmed known interactions between FtsZ and ZipA, and ZapB with itself. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

  18. Bimolecular Excited-State Electron Transfer with Surprisingly Long-Lived Radical Ions

    KAUST Repository

    Alsam, Amani Abdu

    2015-09-02

    We explored the excited-state interactions of bimolecular, non-covalent systems consisting of cationic poly[(9,9-di(3,3’-N,N’-trimethyl-ammonium) propyl fluorenyl-2,7-diyl)-alt-co-(9,9-dioctyl-fluorenyl-2,7-diyl)] diiodide salt (PFN) and 1,4-dicyanobenzene (DCB) using steady-state and time-resolved techniques, including femto- and nanosecond transient absorption and femtosecond infrared spectroscopies with broadband capabilities. The experimental results demonstrated that photo-induced electron transfer from PFN to DCB occurs on the picosecond time scale, leading to the formation of PFN+• and DCB-• radical ions. Interestingly, real-time observations of the vibrational marker modes on the acceptor side provided direct evidence and insight into the electron transfer process indirectly inferred from UV-Vis experiments. The band narrowing on the picosecond time scale observed on the antisymmetric C-N stretching vibration of the DCB radical anion provides clear experimental evidence that a substantial part of the excess energy is channeled into vibrational modes of the electron transfer product and that the geminate ion pairs dissociate. More importantly, our nanosecond time-resolved data indicate that the charge-separated state is very long lived ( 30 ns) due to the dissociation of the contact radical ion pair into free ions. Finally, the fast electron transfer and slow charge recombination anticipate the current donor−acceptor system with potential applications in organic solar cells.

  19. Bimolecular Excited-State Electron Transfer with Surprisingly Long-Lived Radical Ions

    KAUST Repository

    Alsam, Amani Abdu; Aly, Shawkat Mohammede; Usman, Anwar; Parida, Manas R.; Del Gobbo, Silvano; Alarousu, Erkki; Mohammed, Omar F.

    2015-01-01

    We explored the excited-state interactions of bimolecular, non-covalent systems consisting of cationic poly[(9,9-di(3,3’-N,N’-trimethyl-ammonium) propyl fluorenyl-2,7-diyl)-alt-co-(9,9-dioctyl-fluorenyl-2,7-diyl)] diiodide salt (PFN) and 1,4-dicyanobenzene (DCB) using steady-state and time-resolved techniques, including femto- and nanosecond transient absorption and femtosecond infrared spectroscopies with broadband capabilities. The experimental results demonstrated that photo-induced electron transfer from PFN to DCB occurs on the picosecond time scale, leading to the formation of PFN+• and DCB-• radical ions. Interestingly, real-time observations of the vibrational marker modes on the acceptor side provided direct evidence and insight into the electron transfer process indirectly inferred from UV-Vis experiments. The band narrowing on the picosecond time scale observed on the antisymmetric C-N stretching vibration of the DCB radical anion provides clear experimental evidence that a substantial part of the excess energy is channeled into vibrational modes of the electron transfer product and that the geminate ion pairs dissociate. More importantly, our nanosecond time-resolved data indicate that the charge-separated state is very long lived ( 30 ns) due to the dissociation of the contact radical ion pair into free ions. Finally, the fast electron transfer and slow charge recombination anticipate the current donor−acceptor system with potential applications in organic solar cells.

  20. Bimolecular Fluorescence Complementation of Alpha-synuclein Demonstrates its Oligomerization with Dopaminergic Phenotype in Mice

    Directory of Open Access Journals (Sweden)

    Waijiao Cai

    2018-03-01

    Full Text Available Alpha-synuclein (αSyn is encoded by the first causal gene identified in Parkinson's disease (PD and is the main component of Lewy bodies, a pathological hallmark of PD. aSyn-based animal models have contributed to our understanding of PD pathophysiology and to the development of therapeutics. Overexpression of human wildtype αSyn by viral vectors in rodents recapitulates the loss of dopaminergic neurons from the substantia nigra, another defining pathological feature of the disease. The development of a rat model exhibiting bimolecular fluorescence complementation (BiFC of αSyn by recombinant adeno-associated virus facilitates detection of the toxic αSyn oligomers species. We report here neurochemical, neuropathological and behavioral characterization of BiFC of αSyn in mice. Overexpression and oligomerization of αSyn through BiFC is detected by conjugated fluorescence. Reduced striatal dopamine and loss of nigral dopaminergic neurons are accompanied neuroinflammation and abnormal motor activities. Our mouse model may provide a valuable tool to study the role of αSyn in PD and to explore therapeutic approaches. Keywords: Parkinson's disease, Alpha-synuclein, Mouse model, Oligomers, Neuroinflammation

  1. Bimolecular Rate Constants for FAD-Dependent Glucose Dehydrogenase from Aspergillus terreus and Organic Electron Acceptors.

    Science.gov (United States)

    Tsuruoka, Nozomu; Sadakane, Takuya; Hayashi, Rika; Tsujimura, Seiya

    2017-03-10

    The flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH) from Aspergillus species require suitable redox mediators to transfer electrons from the enzyme to the electrode surface for the application of bioelectrical devices. Although several mediators for FAD-GDH are already in use, they are still far from optimum in view of potential, kinetics, sustainability, and cost-effectiveness. Herein, we investigated the efficiency of various phenothiazines and quinones in the electrochemical oxidation of FAD-GDH from Aspergillus terreus . At pH 7.0, the logarithm of the bimolecular oxidation rate constants appeared to depend on the redox potentials of all the mediators tested. Notably, the rate constant of each molecule for FAD-GDH was approximately 2.5 orders of magnitude higher than that for glucose oxidase from Aspergillus sp. The results suggest that the electron transfer kinetics is mainly determined by the formal potential of the mediator, the driving force of electron transfer, and the electron transfer distance between the redox active site of the mediator and the FAD, affected by the steric or chemical interactions. Higher k ₂ values were found for ortho-quinones than for para-quinones in the reactions with FAD-GDH and glucose oxidase, which was likely due to less steric hindrance in the active site in the case of the ortho-quinones.

  2. Bimolecular Rate Constants for FAD-Dependent Glucose Dehydrogenase from Aspergillus terreus and Organic Electron Acceptors

    Directory of Open Access Journals (Sweden)

    Nozomu Tsuruoka

    2017-03-01

    Full Text Available The flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH from Aspergillus species require suitable redox mediators to transfer electrons from the enzyme to the electrode surface for the application of bioelectrical devices. Although several mediators for FAD-GDH are already in use, they are still far from optimum in view of potential, kinetics, sustainability, and cost-effectiveness. Herein, we investigated the efficiency of various phenothiazines and quinones in the electrochemical oxidation of FAD-GDH from Aspergillus terreus. At pH 7.0, the logarithm of the bimolecular oxidation rate constants appeared to depend on the redox potentials of all the mediators tested. Notably, the rate constant of each molecule for FAD-GDH was approximately 2.5 orders of magnitude higher than that for glucose oxidase from Aspergillus sp. The results suggest that the electron transfer kinetics is mainly determined by the formal potential of the mediator, the driving force of electron transfer, and the electron transfer distance between the redox active site of the mediator and the FAD, affected by the steric or chemical interactions. Higher k2 values were found for ortho-quinones than for para-quinones in the reactions with FAD-GDH and glucose oxidase, which was likely due to less steric hindrance in the active site in the case of the ortho-quinones.

  3. [Hypothesis and application of bimolecular marking methods in Chinese materia medica].

    Science.gov (United States)

    Huang, Lu-qi; Qian, Dan; Deng, Chao

    2015-01-01

    Based on the current shortage of genuine/false authentication and quality evaluation in the molecular identification, and the weak functional gene research in the establishment of two-dimensional molecular markering methods for Chinese materia medica, the authors proposed a new method, the bimolecular marking methods (BIMM) for Chinese materia medica, combining DNA marker and metabolomics marker, that could simultaneously research the species and quality differences at the molecular level at the present stage. The authors introduced the concept, principle, methods, and technical process of BIMM, and summarized the technical advantages in this paper. Meanwhile, the application of BIMM in the identification of multiple sources of Chinese materia medica, years-identification, different locations, elite germplasm research, discovery of new drugs resources, protection of new varieties was also discussed. As a supplement of two-dimensional molecular markering method for Chinese materia medica, BIMM would not only expand connotation of identification of Chinese materia medica but also provide another effective way for quality evaluating.

  4. Real-time observation of intersystem crossing induced by charge recombination during bimolecular electron transfer reactions

    KAUST Repository

    Alsam, Amani Abdu

    2016-09-21

    Real-time probing of intersystem crossing (ISC) and triplet-state formation after photoinduced electron transfer (ET) is a particularly challenging task that can be achieved by time-resolved spectroscopy with broadband capability. Here, we examine the mechanism of charge separation (CS), charge recombination (CR) and ISC of bimolecular photoinduced electron transfer (PET) between poly[(9,9-di(3,3′-N,N’-trimethyl-ammonium) propyl fluorenyl-2,7-diyl)-alt-co-(9,9-dioctyl-fluorenyl-2,7-diyl)] diiodide salt (PFN) and dicyanobenzene (DCB) using time-resolved spectroscopy. PET from PFN to DCB is confirmed by monitoring the transient absorption (TA) and infrared spectroscopic signatures for the radical ion pair (DCB─•-PFN+•). In addition, our time-resolved results clearly demonstrate that CS takes place within picoseconds followed by CR within nanoseconds. The ns-TA data exhibit the clear spectroscopic signature of PFN triplet-triplet absorption, induced by the CR of the radical ion pairs (DCB─•-PFN+•). As a result, the triplet state of PFN (3PFN*) forms and subsequently, the ground singlet state is replenished within microseconds. © 2016

  5. Exciplex formation in bimolecular photoinduced electron-transfer investigated by ultrafast time-resolved infrared spectroscopy.

    Science.gov (United States)

    Koch, Marius; Letrun, Romain; Vauthey, Eric

    2014-03-12

    The dynamics of bimolecular photoinduced electron-transfer reactions has been investigated with three donor/acceptor (D/A) pairs in tetrahydrofuran (THF) and acetonitrile (ACN) using a combination of ultrafast spectroscopic techniques, including time-resolved infrared absorption. For the D/A pairs with the highest driving force of electron transfer, all transient spectroscopic features can be unambiguously assigned to the excited reactant and the ionic products. For the pair with the lowest driving force, three additional transient infrared bands, more intense in THF than in ACN, with a time dependence that differs from those of the other bands are observed. From their frequency and solvent dependence, these bands can be assigned to an exciplex. Moreover, polarization-resolved measurements point to a relatively well-defined mutual orientation of the constituents and to a slower reorientational time compared to those of the individual reactants. Thanks to the minimal overlap of the infrared signature of all transient species in THF, a detailed reaction scheme including the relevant kinetic and thermodynamic parameters could be deduced for this pair. This analysis reveals that the formation and recombination of the ion pair occur almost exclusively via the exciplex.

  6. Bimodal Exciplex Formation in Bimolecular Photoinduced Electron Transfer Revealed by Ultrafast Time-Resolved Infrared Absorption.

    Science.gov (United States)

    Koch, Marius; Licari, Giuseppe; Vauthey, Eric

    2015-09-03

    The dynamics of a moderately exergonic photoinduced charge separation has been investigated by ultrafast time-resolved infrared absorption with the dimethylanthracene/phthalonitrile donor/acceptor pair in solvents covering a broad range of polarity. A distinct spectral signature of an exciplex could be identified in the -C≡N stretching region. On the basis of quantum chemistry calculations, the 4-5 times larger width of this band compared to those of the ions and of the locally excited donor bands is explained by a dynamic distribution of exciplex geometry with different mutual orientations and distances of the constituents and, thus, with varying charge-transfer character. Although spectrally similar, two types of exciplexes could be distinguished by their dynamics: short-lived, "tight", exciplexes generated upon static quenching and longer-lived, "loose", exciplexes formed upon dynamic quenching in parallel with ion pairs. Tight exciplexes were observed in all solvents, except in the least polar diethyl ether where quenching is slower than diffusion. The product distribution of the dynamic quenching depends strongly on the solvent polarity: whereas no significant loose exciplex population could be detected in acetonitrile, both exciplex and ion pair are generated in less polar solvents, with the relative population of exciplex increasing with decreasing solvent polarity. These results are compared with those reported previously with donor/acceptor pairs in different driving force regimes to obtain a comprehensive picture of the role of the exciplexes in bimolecular photoinduced charge separation.

  7. AFD: an application for bi-molecular interaction using axial frequency distribution.

    Science.gov (United States)

    Raza, Saad; Azam, Syed Sikander

    2018-03-06

    Conformational flexibility and generalized structural features are responsible for specific phenomena existing in biological pathways. With advancements in computational chemistry, novel approaches and new methods are required to compare the dynamic nature of biomolecules, which are crucial not only to address dynamic functional relationships but also to gain detailed insights into the disturbance and positional fluctuation responsible for functional shifts. Keeping this in mind, axial frequency distribution (AFD) has been developed, designed, and implemented. AFD can profoundly represent distribution and density of ligand atom around a particular atom or set of atoms. It enabled us to obtain an explanation of local movements and rotations, which are not significantly highlighted by any other structural and dynamical parameters. AFD can be implemented on biological models representing ligand and protein interactions. It shows a comprehensive view of the binding pattern of ligand by exploring the distribution of atoms relative to the x-y plane of the system. By taking a relative centroid on protein or ligand, molecular interactions like hydrogen bonds, van der Waals, polar or ionic interaction can be analyzed to cater the ligand movement, stabilization or flexibility with respect to the protein. The AFD graph resulted in the residual depiction of bi-molecular interaction in gradient form which can yield specific information depending upon the system of interest.

  8. Hydrolyses of 2- and 4-fluoro N-heterocycles. 3. Nucleophilic catalysis by buffer bases in the general acid catalyzed hydrolysis of 4-fluoroquinaldine

    International Nuclear Information System (INIS)

    Muscio, O.J. Jr.; Theobald, P.G.; Rutherford, D.R.

    1989-01-01

    Pseudo-first-order rate constants and catalytic rate constants are reported for the buffer-catalyzed hydrolysis of 4-fluoroquinaldine (1) in carboxylic acid and phosphoric acid buffers. The buffer catalysis is consistent with specific acid, general base catalysis. Hydrolyses in 99% 18 O-labeled acetate, indicate that the predominant catalytic mode for the acetic acid/acetate buffer system is nucleophilic catalysis by the acetate anion coupled with specific acid catalysis. The other buffers presumably react in a similar manner. A Broensted-type plot of the catalytic rate constants for hydrolysis of protonated 1 has a slope of 0.57, with formate deviating positively from the line determined by acetate, chloroacetate, monohydrogen phosphate, and water. This Broensted slope is less than that found for hydrolysis of the 2-fluoro-1-methylpyridinium ion, 2, but is still within the range expected for aromatic nucleophilic substitution. Rate constants and 18 O-labeling results for hydrolysis in acetate buffer are also reported for 4-acetoxyquinaldine (3), the proposed intermediate in the acetate-catalyzed hydrolysis of 1. 15 references, 5 figures, 3 tables

  9. Antioxidant activity of selenenamide-based mimic as a function of the aromatic thiols nucleophilicity, a DFT-SAPE model.

    Science.gov (United States)

    Kheirabadi, Ramesh; Izadyar, Mohammad

    2018-05-18

    The mechanism of action of the selenenamide 1 as a mimic of the glutathione peroxidase (GPx) was investigated by the density functional theory. The solvent-assisted proton exchange procedure was applied to model the catalytic behavior and antioxidant activity of this mimic. To have an insight into the charge transfer effect, different aromatic thiols, including electron donating substituents on the phenyl ring were considered. The catalytic behavior of the selenenamide was modeled in a four-step mechanism, described by the oxidation of the mimic, the reduction of the obtained product, selenoxide, the reduction of the selenenylsulfide and dehydration of selenenic acid. On the basis of the activation parameters, the final step of the proposed mechanism is the rate determining states of the catalytic cycle. Turnover frequency (TOF) analysis showed that the electron donating groups at the para-position of the phenyl ring of the PhSH do not affect the catalytic activity of the selenenamide in contrast to p-methyl thiophenol which indicates the highest nucleophilicity. The evaluation of the electronic contribution of the various donating groups on the phenyl ring of the aromatic thiols shows that the antioxidant activity of the selenenamide sufficiently increases in the presence of the electron-donating substitutions. Finally, the charge transfer process at the rate-determining state was investigated based on the natural bond orbital analysis. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. One-pot facile synthesis of 4-amino-1,8-naphthalimide derived Tröger's bases via a nucleophilic displacement approach.

    Science.gov (United States)

    Shanmugaraju, Sankarasekaran; McAdams, Deirdre; Pancotti, Francesca; Hawes, Chris S; Veale, Emma B; Kitchen, Jonathan A; Gunnlaugsson, Thorfinnur

    2017-09-13

    We report here a novel one-pot synthetic strategy for the synthesis of a family of N-alkyl-1,8-naphthalimide based Tröger's bases via a nucleophilic substitution reaction of a common 'precursor' (or a 'synthon') N-aryl-1,8-naphthalimide Tröger's base heated at 80 °C in neat aliphatic primary amine, in overall yield of 65-96%. This methodology provides an efficient and one-step facile route to design 1,8-naphthalimide derived Tröger's base structures in analytically pure form without the use of column chromatography purification, that can be used in medicinal chemistry and as supramolecular scaffolds. We also report the formation of the corresponding anhydride, and the crystallographic analysis of two of the resulting products, that of the N-phenyl-4-amino-1,8-naphthalimide and the anhydride derived Tröger's bases.

  11. Formation of Bimolecular Membranes from Lipid Monolayers and a Study of Their Electrical Properties

    Science.gov (United States)

    Montal, M.; Mueller, P.

    1972-01-01

    Bimolecular membranes are formed from two lipid monolayers at an air-water interface by the apposition of their hydrocarbon chains when an aperture in a Teflon partition separating two aqueous phases is lowered through the interface. Formation of the membrane is monitored by an increase of the electrical capacity, as measured with a voltage clamp. Electrical resistance of the unmodified membrane is analogous to that of conventional planar bilayers (black lipid membranes) prepared in the presence of a hydrocarbon solvent, i.e., 106-108 ohm cm2; the resistance can be lowered to values of 103 ohm cm2 by gramicidin, an antibiotic that modifies the conductance only when the membranes are of biomolecular thickness. In contrast to the resistance, there is a significant difference between the capacity of bilayers made from mono-layers and that of hydrocarbon-containing bilayers made by phase transition; the average values are 0.9 and 0.45 μF cm-2, respectively. The value of 0.9 μF cm-2 approximates that of biological membranes. Assuming a dielectric constant of 2.1 for the hydrocarbon region, the dielectric thickness, as calculated from a capacity of 0.9 μF cm-2, is 22 Å. This value is 6-10 Å smaller than the actual thickness of the hydrocarbon region of bilayers and cell membranes, as determined by x-ray diffraction. The difference may be due to a limited penetration of water into the hydrocarbon region near the ester groups that would lower the electrical resistance of this region and reduce the dielectric thickness. Asymmetric membranes have been formed by adjoining two lipid monolayers of different chemical composition. Images PMID:4509315

  12. Copper-Catalyzed Electrophilic Amination of Organoaluminum Nucleophiles with O-Benzoyl Hydroxylamines.

    Science.gov (United States)

    Zhou, Shuangliu; Yang, Zhiyong; Chen, Xu; Li, Yimei; Zhang, Lijun; Fang, Hong; Wang, Wei; Zhu, Xiancui; Wang, Shaowu

    2015-06-19

    A copper-catalyzed electrophilic amination of aryl and heteroaryl aluminums with N,N-dialkyl-O-benzoyl hydroxylamines that affords the corresponding anilines in good yields has been developed. The catalytic reaction proceeds very smoothly under mild conditions and exhibits good substrate scope. Moreover, the developed catalytic system is also well suited for heteroaryl aluminum nucleophiles, providing facile access to heteroaryl amines.

  13. Nucleophilic additions of [(diethoxyphosphoryl)difluoromethyl]lithium to a,b-unsaturated compounds

    Czech Academy of Sciences Publication Activity Database

    Cherkupally, Prabhakar; Beier, Petr

    2012-01-01

    Roč. 137, May (2012), s. 34-43 ISSN 0022-1139 R&D Projects: GA ČR GP203/08/P310 Institutional research plan: CEZ:AV0Z40550506 Keywords : 1,4-Addition * nucleophilic addition * difluoromethylphosphonate Subject RIV: CC - Organic Chemistry Impact factor: 1.939, year: 2012

  14. Ring opening of a resin-bound chiral aziridine with phenol nucleophiles

    DEFF Research Database (Denmark)

    Ottesen, Lars Korsgaard; Jaroszewski, Jerzy W; Franzyk, Henrik

    2010-01-01

    An efficient and versatile solid-phase route for the preparation of aryl-alkyl ethers is described. Regioselective ring opening of a resin-bound chiral aziridine with phenolic nucleophiles constitutes the key feature of the present protocol that allows incorporation of fluorescent moieties...

  15. Kinetic secondary deuterium isotope effect in addition of nucleophile to m-bromobenzaldehyde

    International Nuclear Information System (INIS)

    Amaral, L. do; Rossi, M.H.

    1985-01-01

    The kinetic secondary deuterium isotope effects, KD/KH for hydrated proton catalyzed addition of semicarbazide, methoxyamine and hydroxylamine to m-bromobenzaldehyde is studied. The nature of the nucleophile, addition of the carbonyl group and the chemical reactions are evaluated. (M.J.C.) [pt

  16. Benzimidazoles and benzoxazoles via the nucleophilic addition of anilines to nitroalkanes.

    Science.gov (United States)

    Aksenov, Alexander V; Smirnov, Alexander N; Aksenov, Nicolai A; Bijieva, Asiyat S; Aksenova, Inna V; Rubin, Michael

    2015-04-14

    PPA-induced umpolung triggers efficient nucleophilic addition of unactivated anilines to nitroalkanes to produce N-hydroxyimidamides. The latter undergo sequential acid-promoted cyclocondensation with ortho-OH or ortho-NHR moieties to afford benzoxazoles and benzimidazoles, respectively.

  17. Organic Chemistry Students' Ideas about Nucleophiles and Electrophiles: The Role of Charges and Mechanisms

    Science.gov (United States)

    Anzovino, Mary E.; Bretz, Stacey Lowery

    2015-01-01

    Organic chemistry students struggle with reaction mechanisms and the electron-pushing formalism (EPF) used by practicing organic chemists. Faculty have identified an understanding of nucleophiles and electrophiles as one conceptual prerequisite to mastery of the EPF, but little is known about organic chemistry students' knowledge of nucleophiles…

  18. Nucleophilic difluoromethylenation of aldehydes and ketones using diethyl difluoro(trimethylsilyl)methylphosphonate

    Czech Academy of Sciences Publication Activity Database

    Alexandrova, Anastasia; Beier, Petr

    2009-01-01

    Roč. 130, č. 5 (2009), s. 493-500 ISSN 0022-1139 R&D Projects: GA ČR GP203/08/P310 Institutional research plan: CEZ:AV0Z40550506 Keywords : phosphonates * phosphates * nucleophilic additions * difluoromethylene Subject RIV: CC - Organic Chemistry Impact factor: 1.730, year: 2009

  19. Living Polymerization of N -Substituted β-Alanine N -Carboxyanhydrides: Kinetic Investigations and Preparation of an Amphiphilic Block Copoly-β-Peptoid

    KAUST Repository

    Grossmann, Arlett; Luxenhofer, Robert

    2012-01-01

    attention. Here we present results that suggest that while N-substituted β-alanine N-carboxyanhydrides can undergo a living nucleophilic ring-opening polymerization, the solubility of poly(β-peptoid)s can be very poor, which contributes to the limited

  20. The Study of Substitution and Elimination Reactions Using Gas Chromatography: An Examination of the Effects of Alkane and Base Structure on Product Distributions

    Science.gov (United States)

    Wharry, Donald L.

    2011-01-01

    An experiment that compares product distribution obtained by either substitution or elimination utilizing alkyl bromides and methoxide, ethoxide, or t-butoxide as the base (or nucleophile) is described. The change in product distribution caused by steric effects of the base and substrate are readily apparent. Prior work on this experiment focused…

  1. Alternative synthesis of 9-{3-[(diisopropoxyphosphoryl)-methoxy]-2-hydroxypropyl}adenine and its free phosphonates substituted at the C-8 position of purine base

    Czech Academy of Sciences Publication Activity Database

    Janeba, Zlatko; Masojídková, Milena; Holý, Antonín

    2010-01-01

    Roč. 75, č. 3 (2010), s. 371-381 ISSN 0010-0765 Institutional research plan: CEZ:AV0Z40550506 Keywords : acyclic nucleoside phosphonates * HPMPA * nucleophilic substitution * intramolecular cyclization Subject RIV: CC - Organic Chemistry Impact factor: 0.853, year: 2010

  2. A Fluorogenic Aromatic Nucleophilic Substitution Reaction for Demonstrating Normal-Phase Chromatography and Isolation of Nitrobenzoxadiazole Chromophores

    Science.gov (United States)

    Key, Jessie A.; Li, Matthew D.; Cairo, Christopher W.

    2011-01-01

    Normal-phase chromatography is an essential technique for monitoring chemical reactions, identifying the presence of specific components, as well as the purification of organic compounds. An experiment to facilitate the instruction and understanding of the concepts behind normal-phase chromatography at the introductory and intermediate…

  3. Automated synthesis of n.c.a. [18F]FDOPA via nucleophilic aromatic substitution with [18F]fluoride

    International Nuclear Information System (INIS)

    Shen, B.; Ehrlichmann, W.; Uebele, M.; Machulla, H.-J.; Reischl, G.

    2009-01-01

    An improved, automated synthesis of [ 18 F]FDOPA including four synthetic steps (fluorination, reductive iodination, alkylation and hydrolysis) is reported with each step optimized individually. In a home-made automatic synthesizer, 9064±3076 MBq of [ 18 F]FDOPA were produced within 120 min from EOB (n=5). Radiochemical purity and enantiomeric excess were both ≥95%. Specific activity was ca. 50 GBq/μmol at EOS. This automatically operable synthesis is well suited for the multi-patient-dose routine production of n.c.a. [ 18 F]FDOPA.

  4. Facile synthesis of 2-amino-4-alkoxypyrimidines via consecutive nucleophilic aromatic substitution (S{sub N}Ar) reaction

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Juhyeon; Cho, Yong Seo [Center for Neuro-Medicine, Brain Science Institute, Korea Institute of Science and Technology, Seoul (Korea, Republic of); Min, Sun Joon [Dept. of Applied Chemistry, Hanyang University , Ansan (Korea, Republic of)

    2016-12-15

    A transition-metal-free and regioselective synthesis of a series of 2-amino-4-alkoxypyrimidines is described. The SNAr alkoxylation of 2,4-dichloropyrimidines regioselectively provided 2-chloro-4-alkoxypyrimidines, which were subsequently subject to the second SNAr amination with cyclic amines in the presence of triethylamine at high temperature to afford 2-amino-4-alkoxypyrimidines in good overall yield.

  5. Simple, heart-smart substitutions

    Science.gov (United States)

    Coronary artery disease - heart smart substitutions; Atherosclerosis - heart smart substitutions; Cholesterol - heart smart substitutions; Coronary heart disease - heart smart substitutions; Healthy diet - heart ...

  6. Breaking the Dogma of Aldolase Specificity: Simple Aliphatic Ketones and Aldehydes are Nucleophiles for Fructose-6-phosphate Aldolase.

    Science.gov (United States)

    Roldán, Raquel; Sanchez-Moreno, Israel; Scheidt, Thomas; Hélaine, Virgil; Lemaire, Marielle; Parella, Teodor; Clapés, Pere; Fessner, Wolf-Dieter; Guérard-Hélaine, Christine

    2017-04-11

    d-Fructose-6-phosphate aldolase (FSA) was probed for extended nucleophile promiscuity by using a series of fluorogenic substrates to reveal retro-aldol activity. Four nucleophiles ethanal, propanone, butanone, and cyclopentanone were subsequently confirmed to be non-natural substrates in the synthesis direction using the wild-type enzyme and its D6H variant. This exceptional widening of the nucleophile substrate scope offers a rapid entry, in good yields and high stereoselectivity, to less oxygenated alkyl ketones and aldehydes, which was hitherto impossible. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Infrared laser induced organic reactions. 2. Laser vs. thermal inducment of unimolecular and hydrogen bromide catalyzed bimolecular dehydration of alcohols

    International Nuclear Information System (INIS)

    Danen, W.C.

    1979-01-01

    It has been demonstrated that a mixture of reactant molecules can be induced by pulsed infrared laser radiation to react via a route which is totally different from the pathway resulting from heating the mixture at 300 0 C. The high-energy unimolecular elimination of H 2 O from ethanol in the presence of 2-propanol and HBr can be selectively induced with a pulsed CO 2 laser in preference to either a lower energy bimolecular HBr-catalyzed dehydration or the more facile dehydration of 2-propanol. Heating the mixture resulted in the almost exclusive reaction of 2-propanol to produce propylene. It was demonstrated that the bimolecular ethanol + HBr reaction cannot be effectively induced by the infrared laser radiation as evidenced by the detrimental effect on the yield of ethylene as the HBr pressure was increased. The selective, nonthermal inducement of H 2 O elimination from vibrationally excited ethanol in the presence of 2-propanol required relatively low reactant pressures. At higher pressures intermolecular V--V energy transfer allowed the thermally more facile dehydration from 2-propanol to become the predominant reaction channel

  8. Efficient Homodifunctional Bimolecular Ring-Closure Method for Cyclic Polymers by Combining RAFT and Self-Accelerating Click Reaction.

    Science.gov (United States)

    Qu, Lin; Sun, Peng; Wu, Ying; Zhang, Ke; Liu, Zhengping

    2017-08-01

    An efficient metal-free homodifunctional bimolecular ring-closure method is developed for the formation of cyclic polymers by combining reversible addition-fragmentation chain transfer (RAFT) polymerization and self-accelerating click reaction. In this approach, α,ω-homodifunctional linear polymers with azide terminals are prepared by RAFT polymerization and postmodification of polymer chain end groups. By virtue of sym-dibenzo-1,5-cyclooctadiene-3,7-diyne (DBA) as small linkers, well-defined cyclic polymers are then prepared using the self-accelerating double strain-promoted azide-alkyne click (DSPAAC) reaction to ring-close the azide end-functionalized homodifunctional linear polymer precursors. Due to the self-accelerating property of DSPAAC ring-closing reaction, this novel method eliminates the requirement of equimolar amounts of telechelic polymers and small linkers in traditional bimolecular ring-closure methods. It facilitates this method to efficiently and conveniently produce varied pure cyclic polymers by employing an excess molar amount of DBA small linkers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Accessing 2-substituted piperidine iminosugars by organometallic addition/intramolecular reductive amination: aldehyde vs. nitrone route.

    Science.gov (United States)

    Mirabella, S; Fibbi, G; Matassini, C; Faggi, C; Goti, A; Cardona, F

    2017-11-07

    A dual synthetic strategy to afford 2-substituted trihydroxypiperidines is disclosed. The procedure involved Grignard addition either to a carbohydrate-derived aldehyde or to a nitrone derived thereof, and took advantage of an efficient ring-closure reductive amination strategy in the final cyclization step. An opposite diastereofacial preference was demonstrated in the nucleophilic attack to the two electrophiles, which would finally produce the same piperidine diastereoisomer as the major product. However, use of a suitable Lewis acid in the Grignard addition to the nitrone allowed reversing the selectivity, giving access to 2-substituted piperidines with the opposite configuration at C-2.

  10. Easy access to nucleophilic boron through diborane to magnesium boryl metathesis

    Science.gov (United States)

    Pécharman, Anne-Frédérique; Colebatch, Annie L.; Hill, Michael S.; McMullin, Claire L.; Mahon, Mary F.; Weetman, Catherine

    2017-04-01

    Organoboranes are some of the most synthetically valuable and widely used intermediates in organic and pharmaceutical chemistry. Their synthesis, however, is limited by the behaviour of common boron starting materials as archetypal Lewis acids such that common routes to organoboranes rely on the reactivity of boron as an electrophile. While the realization of convenient sources of nucleophilic boryl anions would open up a wealth of opportunity for the development of new routes to organoboranes, the synthesis of current candidates is generally limited by a need for highly reducing reaction conditions. Here, we report a simple synthesis of a magnesium boryl through the heterolytic activation of the B-B bond of bis(pinacolato)diboron, which is achieved by treatment of an easily generated magnesium diboranate complex with 4-dimethylaminopyridine. The magnesium boryl is shown to act as an unambiguous nucleophile through its reactions with iodomethane, benzophenone and N,N'-di-isopropyl carbodiimide and by density functional theory.

  11. A General Ligand Design for Gold Catalysis allowing Ligand-Directed Anti Nucleophilic Attack of Alkynes

    Science.gov (United States)

    Wang, Yanzhao; Wang, Zhixun; Li, Yuxue; Wu, Gongde; Cao, Zheng; Zhang, Liming

    2014-01-01

    Most homogenous gold catalyses demand ≥0.5 mol % catalyst loading. Due to the high cost of gold, these reactions are unlikely to be applicable in medium or large scale applications. Here we disclose a novel ligand design based on the privileged biphenyl-2-phosphine framework that offers a potentially general approach to dramatically lowering catalyst loading. In this design, an amide group at the 3’ position of the ligand framework directs and promotes nucleophilic attack at the ligand gold complex-activated alkyne, which is unprecedented in homogeneous gold catalysis considering the spatial challenge of using ligand to reach antiapproaching nucleophile in a linear P-Au-alkyne centroid structure. With such a ligand, the gold(I) complex becomes highly efficient in catalyzing acid addition to alkynes, with a turnover number up to 99,000. Density functional theory calculations support the role of the amide moiety in directing the attack of carboxylic acid via hydrogen bonding. PMID:24704803

  12. Nucleophilic reactions of hydrazido(2-) complexes of molybdenum and tungsten with succinyl dichloride and phenyl isocyanate

    International Nuclear Information System (INIS)

    Iwanami, Kiyotaka; Mizobe, Yasushi; Takahashi, Tamotsu; Kodama, Teruyuki; Uchida, Yasuzo

    1981-01-01

    Nucleophilic attack of the WNNH 2 group in the hydrazido(2-) complex [WF(NNH 2 )(dpe) 2 ][BF 4 ] (dpe = Ph 2 PCH 2 CH 2 PPh 2 ) on succinyl dichloride gives a novel ethanedioylhydrazido(2-) complex, [WF(NNCOCH 2 CH 2 CO)(dpe) 2 ][BF 4 ]. X-Ray structural analysis shows that the carbon, nitrogen, and oxygen atoms of the ethanedioylhydrazido(2-) ligand lie nearly in the same plane, indicating sp 2 character of the nitrogen atom bearing the two carbonyl groups. Phenyl isocyanate also undergoes nucleophilic attack by the hydrazido(2-) complex [MBr(NNH 2 )(dpe) 2 ]Br (M = Mo or W) to yield the phenylsemicarbazido(2-) type complex, [MBr(NNHCONHPh)(dpe) 2 ]Br. Treatment of the semicarbazido(2-) complex with triethylamine gives a new diazenido complex [MBr(NNCONHPh)(dpe) 2 ]. (author)

  13. Barbier Continuous Flow Preparation and Reactions of Carbamoyllithiums for Nucleophilic Amidation.

    Science.gov (United States)

    Ganiek, Maximilian A; Becker, Matthias R; Berionni, Guillaume; Zipse, Hendrik; Knochel, Paul

    2017-08-01

    An ambient temperature continuous flow method for nucleophilic amidation and thioamidation is described. Deprotonation of formamides by lithium diisopropylamine (LDA) affords carbamoyllithium intermediates that are quenched in situ with various electrophiles such as ketones, allyl bromides, Weinreb and morpholino amides. The nature of the reactive lithium intermediates and the thermodynamics of the metalation were further investigated by ab initio calculations and kinetic experiments. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Regioselective Nucleophilic Ring Opening of Epoxides and Aziridines derived from Homoallylic Alcohols

    DEFF Research Database (Denmark)

    Tanner, David Ackland; Groth, Thomas

    1997-01-01

    The regioselectivity of nucleophilic ring opening of some 3,4-epoxy and 3,4-aziridino alcohols has been studied. The nucleophiles chosen were complex hydrides (LiAlH4, Red-Al and DIBAL) and Lipshutz- or Gilman-type organocuprate reagents. The C-4 substituent in the substrates was varied in order...... to study steric and electronic effects on the ring opening reactions. For alkyl substituents at C-4, most of the results can be explained on the basis of intramolecular delivery of the nucleophile to C-3 via a six-membered transition state, leading to 1,4-diols or 1,4-amino alcohol derivatives. In general......, the epoxy alcohols gave poorer regioselectivity than the N-tosyl aziridino alcohols, for which selectivities of >95:5 were routinely obtained. The activating effect of a phenyl group at C-4 led to a switch in regiochemistry, with the 1,3-diol or 1,3-amino alcohol derivative as the major product. (C) 1997...

  15. Electrophilic properties of patulin. Adduct structures and reaction pathways with 4-bromothiophenol and other model nucleophiles.

    Science.gov (United States)

    Fliege, R; Metzler, M

    2000-05-01

    The mycotoxin patulin (PAT) is believed to exert its cytotoxic and chromosome-damaging effects by forming covalent adducts with essential cellular thiols. Since the chemical structures of such adducts are unknown to date, we have studied the reaction of PAT and its O-acetylated derivative with the monofunctional thiol model compound 4-bromothiophenol (BTP), which was chosen due to analytical advantages. By means of analytical and preparative high-performance liquid chromatography, 16 adducts of PAT and 3 adducts of acetyl-PAT were isolated and their chemical structures elucidated by (1)H and (13)C NMR, IR, and UV spectroscopy. Time course studies and analysis of daughter product formation from isolated intermediate adducts led to a detailed scheme for the reaction of PAT with BTP. The structures of adducts of PAT formed with other model nucleophiles, e. g., the aliphatic thiol 2-mercaptoethanol and the aromatic amine 4-bromoaniline, were also elucidated and found to corroborate the reaction scheme. In addition, one further reaction pathway was observed with 2-mercaptoethanol, which appears to be independent from those found for BTP. Our study with model nucleophiles provides insights into the electrophilic reactivity of PAT and proved to be useful for the structure elucidation of PAT adducts with biological nucleophiles of toxicological relevance, as will be reported by Fliege and Metzler [(2000) Chem. Res. Toxicol. 13, 373-381].

  16. Electronic forces as descriptors of nucleophilic and electrophilic regioselectivity and stereoselectivity.

    Science.gov (United States)

    Liu, Shubin; Rong, Chunying; Lu, Tian

    2017-01-04

    One of the main tasks of theoretical chemistry is to rationalize computational results with chemical insights. Key concepts of such nature include nucleophilicity, electrophilicity, regioselectivity, and stereoselectivity. While computational tools are available to predict barrier heights and other reactivity properties with acceptable accuracy, a conceptual framework to appreciate above quantities is still lacking. In this work, we introduce the electronic force as the fundamental driving force of chemical processes to understand and predict molecular reactivity. It has three components but only two are independent. These forces, electrostatic and steric, can be employed as reliable descriptors for nucleophilic and electrophilic regioselectivity and stereoselectivity. The advantages of using these forces to evaluate molecular reactivity are that electrophilic and nucleophilic attacks are featured by distinct characteristics in the electrostatic force and no knowledge of quantum effects included in the kinetic and exchange-correlation energies is required. Examples are provided to highlight the validity and general applicability of these reactivity descriptors. Possible applications in ambident reactivity, σ and π holes, frustrated Lewis pairs, and stereoselective reactions are also included in this work.

  17. The optimization of 18F-nucleophilic fluorination reaction and its application in synthesis of VMAT2 imaging tracer: [18F]AV-133

    International Nuclear Information System (INIS)

    Liu Yajing; Zhu Lin; Karl, P.; Qu Wenchao

    2010-01-01

    Objective: The nucleophilic introduction of n.c.a. [ 18 F]F- into alkanes by nucleophilic reaction is the main method of preparing 18 F-labelled radiopharmaceuticals, and the efficient and rapid reaction is important in 18 F-labelled radiopharmaceuticals. Method: Using 2-(3-substitute propoxy)naphthalene as model compound, the optimal reaction condition was achieved by comparing the different [ 18 F]fluorination condition: 1)different leaving groups (-OTs, -I, -Br and -Cl), 2) different [ 18 F]fluorination catalysts (Kryptofix222/K 2 CO 3 and TBAHCO 3 ), 3) different reaction solvent (ACN, DMSO and DMF), 4) [ 18 F]fluorination temperature (40, 50 and 60 degree C) and 5) reaction time. The radiochemical yields were analyzed by TLC and HPLC. VMAT2 imaging tracer [ 18 F]AV-133 was synthesized under the optimal conditions. Results: From the experiment results, the reation activity was the highest when using -OTs as the leaving group, followed by -I and -Br, -Clunder the [ 18 F]fluorination condition of using K222/K 2 CO 3 as catalyst and ACN as solvent. And also, the radiochemical yield raised as the reaction time and temperature increased. The higher temperature, the shorter time to reach the equilibrium. When changing the solvent from ACN to DMSO, the radiochemical yields were increased. On the contrary, the radiochemical yields were decreasing by using DMF. Comparing the catalyst K222/K 2 CO 3 with TBAHCO 3 , the [ 18 F] fluorination of -OTs gave a higher radiochemical yield in the presence of K222/K 2 CO 3 . So the optimized [ 18 F]fluorination reaction condition was that choosing -OTs as the leaving group, the [ 18 F]fluorination reaction was efficient and gave higher radiochemical yield catalyzed by K222/K 2 CO 3 in DMSO at high temperature. [ 18 F]fluorination of AV-244 was found to provide the VMAT2 imaging tracer [ 18 F]AV-133 in 80 ± 2% radiochemical yield after reaction at 120 degree C for 3 min under optimized conditions. Conclusion: We have described an

  18. Does increasing pressure always accelerate the condensed material decay initiated through bimolecular reactions? A case of the thermal decomposition of TKX-50 at high pressures.

    Science.gov (United States)

    Lu, Zhipeng; Zeng, Qun; Xue, Xianggui; Zhang, Zengming; Nie, Fude; Zhang, Chaoyang

    2017-08-30

    Performances and behaviors under high temperature-high pressure conditions are fundamentals for many materials. We study in the present work the pressure effect on the thermal decomposition of a new energetic ionic salt (EIS), TKX-50, by confining samples in a diamond anvil cell, using Raman spectroscopy measurements and ab initio simulations. As a result, we find a quadratic increase in decomposition temperature (T d ) of TKX-50 with increasing pressure (P) (T d = 6.28P 2 + 12.94P + 493.33, T d and P in K and GPa, respectively, and R 2 = 0.995) and the decomposition under various pressures initiated by an intermolecular H-transfer reaction (a bimolecular reaction). Surprisingly, this finding is contrary to a general observation about the pressure effect on the decomposition of common energetic materials (EMs) composed of neutral molecules: increasing pressure will impede the decomposition if it starts from a bimolecular reaction. Our results also demonstrate that increasing pressure impedes the H-transfer via the enhanced long-range electrostatic repulsion of H +δ H +δ of neighboring NH 3 OH + , with blue shifts of the intermolecular H-bonds. And the subsequent decomposition of the H-transferred intermediates is also suppressed, because the decomposition proceeds from a bimolecular reaction to a unimolecular one, which is generally prevented by compression. These two factors are the basic root for which the decomposition retarded with increasing pressure of TKX-50. Therefore, our finding breaks through the previously proposed concept that, for the condensed materials, increasing pressure will accelerate the thermal decomposition initiated by bimolecular reactions, and reveals a distinct mechanism of the pressure effect on thermal decomposition. That is to say, increasing pressure does not always promote the condensed material decay initiated through bimolecular reactions. Moreover, such a mechanism may be feasible to other EISs due to the similar intermolecular

  19. Tyrosyl-DNA Phosphodiesterase I Catalytic Mutants Reveal an Alternative Nucleophile That Can Catalyze Substrate Cleavage*

    Science.gov (United States)

    Comeaux, Evan Q.; Cuya, Selma M.; Kojima, Kyoko; Jafari, Nauzanene; Wanzeck, Keith C.; Mobley, James A.; Bjornsti, Mary-Ann; van Waardenburg, Robert C. A. M.

    2015-01-01

    Tyrosyl-DNA phosphodiesterase I (Tdp1) catalyzes the repair of 3′-DNA adducts, such as the 3′-phosphotyrosyl linkage of DNA topoisomerase I to DNA. Tdp1 contains two conserved catalytic histidines: a nucleophilic His (Hisnuc) that attacks DNA adducts to form a covalent 3′-phosphohistidyl intermediate and a general acid/base His (Hisgab), which resolves the Tdp1-DNA linkage. A Hisnuc to Ala mutant protein is reportedly inactive, whereas the autosomal recessive neurodegenerative disease SCAN1 has been attributed to the enhanced stability of the Tdp1-DNA intermediate induced by mutation of Hisgab to Arg. However, here we report that expression of the yeast HisnucAla (H182A) mutant actually induced topoisomerase I-dependent cytotoxicity and further enhanced the cytotoxicity of Tdp1 Hisgab mutants, including H432N and the SCAN1-related H432R. Moreover, the HisnucAla mutant was catalytically active in vitro, albeit at levels 85-fold less than that observed with wild type Tdp1. In contrast, the HisnucPhe mutant was catalytically inactive and suppressed Hisgab mutant-induced toxicity. These data suggest that the activity of another nucleophile when Hisnuc is replaced with residues containing a small side chain (Ala, Asn, and Gln), but not with a bulky side chain. Indeed, genetic, biochemical, and mass spectrometry analyses show that a highly conserved His, immediately N-terminal to Hisnuc, can act as a nucleophile to catalyze the formation of a covalent Tdp1-DNA intermediate. These findings suggest that the flexibility of Tdp1 active site residues may impair the resolution of mutant Tdp1 covalent phosphohistidyl intermediates and provide the rationale for developing chemotherapeutics that stabilize the covalent Tdp1-DNA intermediate. PMID:25609251

  20. Nucleophilic Fluorination Reactions in Novel Reaction Media for 18F-Fluorine Labeling Method

    International Nuclear Information System (INIS)

    Kim, Dong Wook; Jeong, Hwan Jeong; Lim, Seok Tae; Sohn, Myung Hee

    2009-01-01

    Noninvasive imaging of molecular and biological processes in living subjects with positron emission tomography (PET) provides exciting opportunities to monitor metabolism and detect diseases in humans. Measuring these processes with PET requires the preparation of specific molecular imaging probes labeled with 18F-fluorine. In this review we describe recent methods and novel trends for the introduction of 18 F-fluorine into molecules which in turn are intended to serve as imaging agents for PET study. Nucleophilic 18 F-fluorination of some halo- and mesyloxyalkanes to the corresponding 18 F-fluoroalkanes with 18 F-fluoride obtained from an 18 O(p,n) 18 F reaction, using novel reaction media system such as an ionic liquidor tert-alcohol, has been studied as a new method for 18 F-fluorine labeling. Ionic liquid method is rapid and particularly convenient because 18 F-fluoride in H 2 O can be added directly to the reaction media, obviating the careful drying that is typically required for currently used radiofluorination methods. The nonpolar protic tert-alcohol enhances the nucleophilicity of the fluoride ion dramatically in the absence of any kind of catalyst, greatly increasing the rate of the nucleophilic fluorination and reducing formation of byproducts compared with conventional methods using dipolar aprotic solvents. The great efficacy of this method is a particular advantage in labeling radiopharmaceuticals with 18 F-fluorine for PET imaging, and it is illustrated by the synthesis of 18 F-fluoride radiolabeled molecular imaging probes, such as 18 F-FDG, 18 F-FLT, 18 F-FP-CIT, and 18 F-FMISO, in high yield and purity and in shorter times compared to conventional syntheses

  1. Abstraction of methyl from neutral Fischer-type carbene complexes: A new site for nucleophilic attack

    Energy Technology Data Exchange (ETDEWEB)

    Toomey, L.M.; Atwood, J.D. [State Univ. of New York, Buffalo, NY (United States)

    1997-02-04

    Reactions of Fischer-type carbene complexes, M(CO){sub 5}(C(OMe)pH) (M = Cr, W), with metal carbonyl anions (M`{sup -} = CpFe(CO){sub 2}{sup -@}, Re(CO){sub 5}{sup -}, Mn(CO){sub 4}PPh{sub 3}{sup -}, Co(CO){sub 3}PPh{sub 3}{sup -}, Cp{sup *}Cr(CO){sub 3}{sup -}, CpMo(CO){sub 3}{sup -}) result in demethylation of the carbene complexes. The products are M(CO){sub 5}C(O)Ph{sup -} and M`-Me, characterized by infrared and NMR spectroscopy. A slower rate for reaction with W(CO){sub 5}(C(OEt)Ph) in comparison to the methyl analogue is consistent with nucleophilic attack of the metal carbonyl anion on the methyl of the methoxy group of the carbene. This is a new type of nucleophilic attack of a Fischer-type carbene. 22 refs., 1 fig., 1 tab.

  2. Medicineringsfejl ved generisk substitution

    DEFF Research Database (Denmark)

    Rölfing, Jan

    2012-01-01

    Generic substitution is a major cause of medical mistakes in the general population. Danish legislation obligates pharmacies to substitute prescribed medicine with the cheapest equivalent formulation, despite variations in product name, packaging, shape and colour. Consequently, medical mistakes...... occur. Scientific evidence on the consequences of generic substitution is sparse. Call upon fellow health workers to report medical mistakes to the national entities and scientific peers, in order to increase awareness and scientific evidence about the problem....

  3. Ring rearrangements and reactivity of 3-((4-oxo-4H-chromen-3-ylmethylene-4-phenyl-1H-[1,5]benzodiazepin-2(3H-one toward some nucleophiles

    Directory of Open Access Journals (Sweden)

    Hanan Salah

    2017-05-01

    Full Text Available Condensation of 4-phenyl-1H-[1,5]benzodiazepin-2(3H-one (1 with 3-formylchromone (2 afforded a mixture of 3-(chromenylmethylene[1,5]benzodiazepinone 3 and 14-chromenylbenzodiazepino[2,3:6,5]pyrano[2,3-b]benzodiazepine 4. Ring rearrangements of compound 3 with different nucleophilic reagents, such as potassium hydroxide and/or ammonium acetate led to rearrangement into pyranobenzodiazepine 5 and pyridobenzodiazepine 6, respectively. Treatment of compound 3 with hydrazine hydrate, hydroxylamine hydrochloride, malononitrile, cyanothioacetamide, 2-cyano-3,3-disufanylacrylonitrile, and/or 2-cyano-3-phenylamino-3-sufanylacrylonitrile, has been carried out at different conditions, leading to versatile heterocyclic substituted benzodiazepines at position 3, viz. pyrazole 8, isoxazole 9, pyridines 10 and 11, 1,3-dithiine 12, and 1,3-thiazine 13 derivatives.

  4. Bimolecular Complementation to Visualize Filovirus VP40-Host Complexes in Live Mammalian Cells: Toward the Identification of Budding Inhibitors

    Directory of Open Access Journals (Sweden)

    Yuliang Liu

    2011-01-01

    Full Text Available Virus-host interactions play key roles in promoting efficient egress of many RNA viruses, including Ebola virus (EBOV or “e” and Marburg virus (MARV or “m”. Late- (L- domains conserved in viral matrix proteins recruit specific host proteins, such as Tsg101 and Nedd4, to facilitate the budding process. These interactions serve as attractive targets for the development of broad-spectrum budding inhibitors. A major gap still exists in our understanding of the mechanism of filovirus budding due to the difficulty in detecting virus-host complexes and mapping their trafficking patterns in the natural environment of the cell. To address this gap, we used a bimolecular complementation (BiMC approach to detect, localize, and follow the trafficking patterns of eVP40-Tsg101 complexes in live mammalian cells. In addition, we used the BiMC approach along with a VLP budding assay to test small molecule inhibitors identified by in silico screening for their ability to block eVP40 PTAP-mediated interactions with Tsg101 and subsequent budding of eVP40 VLPs. We demonstrated the potential broad spectrum activity of a lead candidate inhibitor by demonstrating its ability to block PTAP-dependent binding of HIV-1 Gag to Tsg101 and subsequent egress of HIV-1 Gag VLPs.

  5. Switching and sensing spin states of co-porphyrin in bimolecular reactions on Au111 using scanning tunneling microscopy.

    Science.gov (United States)

    Kim, Howon; Chang, Yun Hee; Lee, Soon-Hyeong; Kim, Yong-Hyun; Kahng, Se-Jong

    2013-10-22

    Controlling and sensing spin states of magnetic molecules at the single-molecule level is essential for spintronic molecular device applications. Here, we demonstrate that spin states of Co-porphyrin on Au(111) can be reversibly switched over by binding and unbinding of the NO molecule and can be sensed using scanning tunneling microscopy and spectroscopy (STM and STS). Before NO exposure, Co-porphryin showed a clear zero-bias peak, a signature of Kondo effect in STS, whereas after NO exposures, it formed a molecular complex, NO-Co-porphyrin, that did not show any zero-bias feature, implying that the Kondo effect was switched off by binding of NO. The Kondo effect could be switched back on by unbinding of NO through single-molecule manipulation or thermal desorption. Our density functional theory calculation results explain the observations with pairing of unpaired spins in dz(2) and ppπ* orbitals of Co-porphyrin and NO, respectively. Our study opens up ways to control molecular spin state and Kondo effect by means of enormous variety of bimolecular binding and unbinding reactions on metallic surfaces.

  6. The influence of the “cage effect” on the mechanism of reversible bimolecular multistage chemical reactions in solutions

    International Nuclear Information System (INIS)

    Doktorov, Alexander B.

    2015-01-01

    Manifestations of the “cage effect” at the encounters of reactants are theoretically treated by the example of multistage reactions in liquid solutions including bimolecular exchange reactions as elementary stages. It is shown that consistent consideration of quasi-stationary kinetics of multistage reactions (possible only in the framework of the encounter theory) for reactions proceeding near reactants contact can be made on the basis of the concepts of a “cage complex.” Though mathematically such a consideration is more complicated, it is more clear from the standpoint of chemical notions. It is established that the presence of the “cage effect” leads to some important effects not inherent in reactions in gases or those in solutions proceeding in the kinetic regime, such as the appearance of new transition channels of reactant transformation that cannot be caused by elementary event of chemical conversion for the given mechanism of reaction. This results in that, for example, rate constant values of multistage reaction defined by standard kinetic equations of formal chemical kinetics from experimentally measured kinetics can differ essentially from real values of these constants

  7. The influence of the "cage effect" on the mechanism of reversible bimolecular multistage chemical reactions in solutions.

    Science.gov (United States)

    Doktorov, Alexander B

    2015-08-21

    Manifestations of the "cage effect" at the encounters of reactants are theoretically treated by the example of multistage reactions in liquid solutions including bimolecular exchange reactions as elementary stages. It is shown that consistent consideration of quasi-stationary kinetics of multistage reactions (possible only in the framework of the encounter theory) for reactions proceeding near reactants contact can be made on the basis of the concepts of a "cage complex." Though mathematically such a consideration is more complicated, it is more clear from the standpoint of chemical notions. It is established that the presence of the "cage effect" leads to some important effects not inherent in reactions in gases or those in solutions proceeding in the kinetic regime, such as the appearance of new transition channels of reactant transformation that cannot be caused by elementary event of chemical conversion for the given mechanism of reaction. This results in that, for example, rate constant values of multistage reaction defined by standard kinetic equations of formal chemical kinetics from experimentally measured kinetics can differ essentially from real values of these constants.

  8. The influence of the “cage effect” on the mechanism of reversible bimolecular multistage chemical reactions in solutions

    Energy Technology Data Exchange (ETDEWEB)

    Doktorov, Alexander B., E-mail: doktorov@kinetics.nsc.ru [Voevodsky Institute of Chemical Kinetics & Combustion, Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia and Novosibirsk State University, Novosibirsk 630090 (Russian Federation)

    2015-08-21

    Manifestations of the “cage effect” at the encounters of reactants are theoretically treated by the example of multistage reactions in liquid solutions including bimolecular exchange reactions as elementary stages. It is shown that consistent consideration of quasi-stationary kinetics of multistage reactions (possible only in the framework of the encounter theory) for reactions proceeding near reactants contact can be made on the basis of the concepts of a “cage complex.” Though mathematically such a consideration is more complicated, it is more clear from the standpoint of chemical notions. It is established that the presence of the “cage effect” leads to some important effects not inherent in reactions in gases or those in solutions proceeding in the kinetic regime, such as the appearance of new transition channels of reactant transformation that cannot be caused by elementary event of chemical conversion for the given mechanism of reaction. This results in that, for example, rate constant values of multistage reaction defined by standard kinetic equations of formal chemical kinetics from experimentally measured kinetics can differ essentially from real values of these constants.

  9. The bimolecular reaction of radiolysis product of hydrated electron at temperature up to 473K; Reaksi bimolekular antar produk radiolisis elektron terhidrasi pada temperatur hingga 473K

    Energy Technology Data Exchange (ETDEWEB)

    Sunaryo, G R [Reactor Safety Technology Research Centre, National Atomic Energy Agency, Serpong (Indonesia)

    1996-06-01

    Rate constant from the bimolecular reaction of hydrated electron was determined by using radiolysis method. The methanol solution with concentration of 5 x 10{sup -2} dm{sup 3} mol{sup -1} was used as a scavenger of H and OH radicals. The pH was kept by adding the buffer solution of 1.0 x 10{sup -3} dm{sup 3} mol{sup -1} Na{sub 2}HPO{sub 4} + 1.0 x 10{sup 4} dm{sup 3} mol{sup -1} NaH{sub 2}PO{sub 4}. The irradiation was done by using the electron beam which come from linear accelerator 28 MeV with pulse width 10ns and dose of 80 Gy per pulse. The absorbance of hydrated electron was observed at wavelength of 824 nm. By using the kinetic equation the rate reaction constants were obtained. The bimolecular reaction of hydrated electron increase with temperature up to 423K. The activation energy was 19.3 kJ mol{sup -1} and the 2 k (298K) was 1.1 x 10{sup 10} dm{sup 3} mol{sup -1}. Then this bimolecular reaction decrease at temperature higher than 423K and the rate reaction constant at 473K almost similar with that at 298K. (author)

  10. Computational study of the rate constants and free energies of intramolecular radical addition to substituted anilines

    Directory of Open Access Journals (Sweden)

    Andreas Gansäuer

    2013-08-01

    Full Text Available The intramolecular radical addition to aniline derivatives was investigated by DFT calculations. The computational methods were benchmarked by comparing the calculated values of the rate constant for the 5-exo cyclization of the hexenyl radical with the experimental values. The dispersion-corrected PW6B95-D3 functional provided very good results with deviations for the free activation barrier compared to the experimental values of only about 0.5 kcal mol−1 and was therefore employed in further calculations. Corrections for intramolecular London dispersion and solvation effects in the quantum chemical treatment are essential to obtain consistent and accurate theoretical data. For the investigated radical addition reaction it turned out that the polarity of the molecules is important and that a combination of electrophilic radicals with preferably nucleophilic arenes results in the highest rate constants. This is opposite to the Minisci reaction where the radical acts as nucleophile and the arene as electrophile. The substitution at the N-atom of the aniline is crucial. Methyl substitution leads to slower addition than phenyl substitution. Carbamates as substituents are suitable only when the radical center is not too electrophilic. No correlations between free reaction barriers and energies (ΔG‡ and ΔGR are found. Addition reactions leading to indanes or dihydrobenzofurans are too slow to be useful synthetically.

  11. Effect of 2-methyl-substituted nitroimidazoles on the hydrolysis of 4-nitrophenyl esters. Suffield report

    Energy Technology Data Exchange (ETDEWEB)

    Clewley, R.G.; Adie, C.P.; Brouwer, B.H.

    1994-03-01

    Prior to investigating nitroimidazole surfactants for use in a new catalytic chemical agent decontaminant, the catalysis afforded by simple nitroimidazoles in hydrolysis reactions has been examined. The effect of 2-methyl-5-nitroimidazole on the hydrolysis of 4-nitrophenyl diphenylphosphinate and of 2-methyl-5-nitrobenzimidazole on the hydrolyses of both 4-nitrophenyl diphenylphosphinate and 4-nitrophenyl acetate has been determined. In all three cases there is a simple linear dependency of the reaction rate on the concentration of the anionic form of the nitroimidazole. Previous results had suggested self-inhibition by the nucleophile occurred in the 2-methyl-5-nitroimidazole catalysed hydrolysis of 4-nitrophenyl diphenylphosphinate; this hypothesis is no longer tenable. Comparison of the reactivity of 2-methyl -substituted nitroimidazolides to that of the corresponding unsubstituted species suggests that 2-alkyl-substituted nitroionidazole surfactants would not be significantly worse catalysts of the hydrolysis of organophosphorus species than their 4-substituted analogues. Decontamination, Chemical reactivity, Displacement reactions, Nucleophilic reactions, Imidazoles, Nitroimidazoles, Phenoxides, Simulants, UV Spectrophotometry, Mechanism.

  12. Mechanism of Oxidative Amidation of Nitroalkanes with Oxygen and Amine Nucleophiles by Using Electrophilic Iodine.

    Science.gov (United States)

    Li, Jing; Lear, Martin J; Kwon, Eunsang; Hayashi, Yujiro

    2016-04-11

    Recently, we developed a direct method to oxidatively convert primary nitroalkanes into amides that entailed mixing an iodonium source with an amine, base, and oxygen. Herein, we systematically investigated the mechanism and likely intermediates of such methods. We conclude that an amine-iodonium complex first forms through N-halogen bonding. This complex reacts with aci-nitronates to give both α-iodo- and α,α-diiodonitroalkanes, which can act as alternative sources of electrophilic iodine and also generate an extra equimolar amount of I(+) under O2. In particular, evidence supports α,α-diiodonitroalkane intermediates reacting with molecular oxygen to form a peroxy adduct; alternatively, these tetrahedral intermediates rearrange anaerobically to form a cleavable nitrite ester. In either case, activated esters are proposed to form that eventually reacts with nucleophilic amines in a traditional fashion. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Synthesis of D-fructose-derived spirocyclic 2-substituted-2-oxazoline ribosides

    Directory of Open Access Journals (Sweden)

    Madhuri Vangala

    2015-11-01

    Full Text Available The TMSOTf-mediated synthesis of β-configured spirocyclic 2-substituted-2-oxazoline ribosides was achieved using a “Ritter-like” reaction in toluene through nucleophilic addition of electron-rich nitriles to the oxacarbenium ion intermediate of 1,2;3,4-di-O-isopropylidene-β-D-psicofuranose derivatives with concomitant intramolecular trapping of the C2 hydroxymethyl group on the electrophilic nitrilium carbon. These carbohydrate-derived spirooxazolines are stable and were obtained in good yield with high stereoselectivity due to the conformational rigidity imparted by the 3,4-isopropylidene group.

  14. Nucleophilic radioiodination of 6-bromocholesterol via non-isotopic exchange reaction in molten state

    International Nuclear Information System (INIS)

    El-Shaboury, G.; Farah, K.; El-Tawoosy, M.

    2001-01-01

    A synthetic method for preparing radioiodinated 6-[ 125 I]iodocholesterol [CL-6- 125 I] for adrenal evaluation is described. The radioiodine atom was incorporated onto the cholesterol molecule via non-isotopic exchange between 6-bromocholesterol [CL-6-Br] and radioiodine as iodide ion [ 125 I - ] in a molten state. The different parameters affecting the yield of exchange were investigated using 125 I (T 1/2 ≅ 60 d) to centralize the different physical and chemical reaction conditions and purification of the final product as pure as 6-[ 125 I]iodocholesterol. The method was suitable to either 131 I (T 1/2 ≅ 8 d) nucleophilic radioiodination which facilitates the scanning of the adrenal for a few days after administration or the use of 124 I (T 1/2 ≅ 4.16 d) nucleophilic radioiodination for PET evaluation of the adrenal. TLC as well as HPLC chromatographic analysis is used to determine the efficiency of the exchange reactions under different chemical reaction conditions and to monitor the stability of the final product as pure as CL-6- 125 I with radiochemical purity of ≅99%. This no-carrier-added method improved the speed of the reaction and affords high radiochemical yield of 90% and suitable specific activity due to the use of CL-6-Br rather than CL-6-I as substrate. Kinetic studies revealed second order iodine-bromine exchange reaction. The activation energy for the exchange reaction in ammonium acetate (m.p. 114 deg C) was calculated to be 4.576 kcal/mole. (author)

  15. The development of catalytic nucleophilic additions of terminal alkynes in water.

    Science.gov (United States)

    Li, Chao-Jun

    2010-04-20

    One of the major research endeavors in synthetic chemistry over the past two decades is the exploration of synthetic methods that work under ambient atmosphere with benign solvents, that maximize atom utilization, and that directly transform natural resources, such as renewable biomass, from their native states into useful chemical products, thus avoiding the need for protecting groups. The nucleophilic addition of terminal alkynes to various unsaturated electrophiles is a classical (textbook) reaction in organic chemistry, allowing the formation of a C-C bond while simultaneously introducing the alkyne functionality. A prerequisite of this classical reaction is the stoichiometric generation of highly reactive metal acetylides. Over the past decade, our laboratory and others have been exploring an alternative, the catalytic and direct nucleophilic addition of terminal alkynes to unsaturated electrophiles in water. We found that various terminal alkynes can react efficiently with a wide range of such electrophiles in water (or organic solvent) in the presence of simple and readily available catalysts, such as copper, silver, gold, iron, palladium, and others. In this Account, we describe the development of these synthetic methods, focusing primarily on results from our laboratory. Our studies include the following: (i) catalytic reaction of terminal alkynes with acid chloride, (ii) catalytic addition of terminal alkynes to aldehydes and ketones, (iii) catalytic addition of alkynes to C=N bonds, and (iv) catalytic conjugate additions. Most importantly, these reactions can tolerate various functional groups and, in many cases, perform better in water than in organic solvents, clearly defying classical reactivities predicated on the relative acidities of water, alcohols, and terminal alkynes. We further discuss multicomponent and enantioselective reactions that were developed. These methods provide an alternative to the traditional requirement of separate steps in

  16. Nucleophilic 18F-Labeling of Spirocyclic Iodonium Ylide or Boronic Pinacol Ester Precursors - Advantages and Disadvantages

    DEFF Research Database (Denmark)

    Petersen, Ida Nymann; Kristensen, Jesper Langgaard; Herth, Matthias Manfred

    2017-01-01

    The field of labeling electron-rich aryl compounds with nucleophilic [18F]fluoride has recently expanded with radiofluorination strategies that apply boronic esters or spirocyclic iodonium ylides as precursors. Herein, we present a direct comparison of these strategies by using nine chemically di...

  17. Chemistry of [(Perfluoroalkyl)Methyl] Oxiranes. Regioselectivity of Ring Opening with O-Nucleophiles and the Preparation of Amphiphilic Monomers

    Czech Academy of Sciences Publication Activity Database

    Církva, Vladimír; Améduri, B.; Boutevin, B.; Paleta, O.

    1997-01-01

    Roč. 84, č. 1 (1997), s. 53-61 ISSN 0022-1139 Institutional research plan: CEZ:AV0Z4072921 Keywords : fluoroalkyl thiiranes * nucleophilic oxirane ring opening Subject RIV: CC - Organic Chemistry Impact factor: 0.714, year: 1997

  18. Organic Chemistry Students' Fragmented Ideas about the Structure and Function of Nucleophiles and Electrophiles: A Concept Map Analysis

    Science.gov (United States)

    Anzovino, Mary E.; Bretz, Stacey Lowery

    2016-01-01

    Organic chemistry students struggle with multiple aspects of reaction mechanisms and the curved arrow notation used by organic chemists. Many faculty believe that an understanding of nucleophiles and electrophiles, among other concepts, is required before students can develop fluency with the electronpushing formalism (EPF). An expert concept map…

  19. 40 CFR 721.981 - Substituted naphtholoazo-substituted naphthalenyl-substituted azonaphthol chromium complex.

    Science.gov (United States)

    2010-07-01

    ... naphthalenyl-substituted azonaphthol chromium complex. 721.981 Section 721.981 Protection of Environment...-substituted naphthalenyl-substituted azonaphthol chromium complex. (a) Chemical substance and significant new... naphtholoazo-substituted naphthalenyl-substituted azonaphthol chromium complex (PMN P-93-1631) is subject to...

  20. Electricity/oil substitution

    International Nuclear Information System (INIS)

    Melvin, J.G.

    1980-09-01

    The extent to which electricity could substitute for imported oil in Canada is assessed and it is concluded that the bulk of projected oil imports could be displaced. This substitution of electricity for oil could be largely completed within two decades, with existing technology, using Canadian resources. The substitution of electricity for imported oil would result in relatively low energy costs and would stimulate economic growth. Energy self-sufficiency through the substitution of electricity for oil is uniquely a Canadian option; it is not open to other industrial countries. The option exists because of Canada's resources of oil sands for essential liquid fuels, hydraulic and nuclear electrical potential, and natural gas as an interim source of energy. While other countries face an energy crisis due to declining supplies of oil, Canada faces opportunities. The policies of Federal and Provincial governments, as perceived by individual decision makers, will have a major influence on Canada's ability to realize opportunities. (auth)

  1. Straightforward Entry toward Highly Substituted 2,3-Dihydrobenz[ b]oxepines by Ring Expansion of Benzopyryliums with Donor-Acceptor Diazo Compounds.

    Science.gov (United States)

    Courant, Thibaut; Pasco, Morgane; Lecourt, Thomas

    2018-05-04

    Ylide-type reactivity of diazo compounds is exploited in a new way to prepare benzo[ b]oxepines thanks to the formation of three chemical bonds and two contiguous and highly substituted stereocenters in a single pot. This cationic reaction cascade first involves addition of a donor-acceptor-substituted diazo compound to a benzopyrylium. Selective 1,2 migration of the endocyclic C-C bond then results in a ring-expansion and generates a second oxocarbenium that is trapped by a nucleophile added sequentially.

  2. Use of X-ray diffraction, molecular simulations, and spectroscopy to determine the molecular packing in a polymer-fullerene bimolecular crystal

    KAUST Repository

    Miller, Nichole Cates

    2012-09-05

    The molecular packing in a polymer: fullerene bimolecular crystal is determined using X-ray diffraction (XRD), molecular mechanics (MM) and molecular dynamics (MD) simulations, 2D solid-state NMR spectroscopy, and IR absorption spectroscopy. The conformation of the electron-donating polymer is significantly disrupted by the incorporation of the electron-accepting fullerene molecules, which introduce twists and bends along the polymer backbone and 1D electron-conducting fullerene channels. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Enhanced bimolecular exchange reaction through programmed coordination of a five-coordinate oxovanadium complex for efficient redox mediation in dye-sensitized solar cells.

    Science.gov (United States)

    Oyaizu, Kenichi; Hayo, Noriko; Sasada, Yoshito; Kato, Fumiaki; Nishide, Hiroyuki

    2013-12-07

    Electrochemical reversibility and fast bimolecular exchange reaction found for VO(salen) gave rise to a highly efficient redox mediation to enhance the photocurrent of a dye-sensitized solar cell, leading to an excellent photovoltaic performance with a conversion efficiency of 5.4%. A heterogeneous electron-transfer rate constant at an electrode (k0) and a second-order rate constant for an electron self-exchange reaction (k(ex)) were proposed as key parameters that dominate the charge transport property, which afforded a novel design concept for the mediators based on their kinetic aspects.

  4. Use of X-ray diffraction, molecular simulations, and spectroscopy to determine the molecular packing in a polymer-fullerene bimolecular crystal

    KAUST Repository

    Miller, Nichole Cates; Cho, Eunkyung; Junk, Matthias J N; Gysel, Roman; Risko, Chad; Kim, Dongwook; Sweetnam, Sean; Miller, Chad E.; Richter, Lee J.; Kline, Regis Joseph; Heeney, Martin J.; McCulloch, Iain A.; Amassian, Aram; Acevedo-Feliz, Daniel; Knox, Christopher; Hansen, Michael Ryan; Dudenko, Dmytro V.; Chmelka, Bradley F.; Toney, Michael F.; Bré das, Jean Luc; McGehee, Michael D.

    2012-01-01

    The molecular packing in a polymer: fullerene bimolecular crystal is determined using X-ray diffraction (XRD), molecular mechanics (MM) and molecular dynamics (MD) simulations, 2D solid-state NMR spectroscopy, and IR absorption spectroscopy. The conformation of the electron-donating polymer is significantly disrupted by the incorporation of the electron-accepting fullerene molecules, which introduce twists and bends along the polymer backbone and 1D electron-conducting fullerene channels. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Probing the reactivity of nucleophile residues in human 2,3-diphosphoglycerate/deoxy-hemoglobin complex by aspecific chemical modifications.

    Science.gov (United States)

    Scaloni, A; Ferranti, P; De Simone, G; Mamone, G; Sannolo, N; Malorni, A

    1999-06-11

    The use of aspecific methylation reaction in combination with MS procedures has been employed for the characterization of the nucleophilic residues present on the molecular surface of the human 2,3-diphosphoglycerate/deoxy-hemoglobin complex. In particular, direct molecular weight determinations by ESMS allowed to control the reaction conditions, limiting the number of methyl groups introduced in the modified globin chains. A combined LCESMS-Edman degradation approach for the analysis of the tryptic peptide mixtures yielded to the exact identification of methylation sites together with the quantitative estimation of their degree of modification. The reactivities observed were directly correlated with the pKa and the relative surface accessibility of the nucleophilic residues, calculated from the X-ray crystallographic structure of the protein. The results here described indicate that this methodology can be efficiently used in aspecific modification experiments directed to the molecular characterization of the surface topology in proteins and protein complexes.

  6. Hydroxylation of p-substituted phenols by tyrosinase: Further insight into the mechanism of tyrosinase activity

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Munoz, Jose Luis [GENZ - Grupo de Investigacion Enzimologia, Departamento de Bioquimica y Biologia Molecular-A, Facultad de Biologia, Campus Internacional de Excelencia Campus Mare Nostrum, Universidad de Murcia, E-30100 Espinardo, Murcia (Spain); Berna, Jose [Grupo de Quimica Organica Sintetica, Departamento de Quimica Organica, Facultad de Quimica Campus Internacional de Excelencia Campus Mare Nostrum, Universidad de Murcia (Spain); Garcia-Molina, Maria del Mar; Garcia-Molina, Francisco [GENZ - Grupo de Investigacion Enzimologia, Departamento de Bioquimica y Biologia Molecular-A, Facultad de Biologia, Campus Internacional de Excelencia Campus Mare Nostrum, Universidad de Murcia, E-30100 Espinardo, Murcia (Spain); Garcia-Ruiz, Pedro Antonio [QCPAI - Grupo de Quimica de Carbohidratos, Polimeros y Aditivos Industriales, Departamento de Quimica Organica, Facultad de Quimica Campus Internacional de Excelencia Campus Mare Nostrum, Universidad de Murcia (Spain); Varon, Ramon [Departamento de Quimica-Fisica, Escuela de Ingenieros Industriales de Albacete, Universidad de Castilla la Mancha, Avda. Espana s/n. Campus Universitario, E-02071 Albacete (Spain); and others

    2012-07-27

    Highlights: Black-Right-Pointing-Pointer The action the copper complexes and tyrosinase on phenols is equivalent. Black-Right-Pointing-Pointer Isotope effect showed that nucleophilic attack to copper atom may be the slower step. Black-Right-Pointing-Pointer The value of {rho} (Hammett constant) supports an electrophilic aromatic substitution. Black-Right-Pointing-Pointer Data obtained in steady state pH 7 conditions support the mechanism of Scheme 1SM. -- Abstract: A study of the monophenolase activity of tyrosinase by measuring the steady state rate with a group of p-substituted monophenols provides the following kinetic information: k{sub cat}{sup m} and the Michaelis constant, K{sub M}{sup m}. Analysis of these data taking into account chemical shifts of the carbon atom supporting the hydroxyl group ({delta}) and {sigma}{sub p}{sup +}, enables a mechanism to be proposed for the transformation of monophenols into o-diphenols, in which the first step is a nucleophilic attack on the copper atom on the form E{sub ox} (attack of the oxygen of the hydroxyl group of C-1 on the copper atom) followed by an electrophilic attack (attack of the hydroperoxide group on the ortho position with respect to the hydroxyl group of the benzene ring, electrophilic aromatic substitution with a reaction constant {rho} of -1.75). These steps show the same dependency on the electronic effect of the substituent groups in C-4. Furthermore, a study of a solvent deuterium isotope effect on the oxidation of monophenols by tyrosinase points to an appreciable isotopic effect. In a proton inventory study with a series of p-substituted phenols, the representation of k{sub cat}{sup f{sub n}}/k{sub cat}{sup f{sub 0}} against n (atom fractions of deuterium), where k{sub cat}{sup f{sub n}} is the catalytic constant for a molar fraction of deuterium (n) and k{sub cat}{sup f{sub 0}} is the corresponding kinetic parameter in a water solution, was linear for all substrates. These results indicate that

  7. Hydroxylation of p-substituted phenols by tyrosinase: Further insight into the mechanism of tyrosinase activity

    International Nuclear Information System (INIS)

    Muñoz-Muñoz, Jose Luis; Berna, Jose; García-Molina, María del Mar; Garcia-Molina, Francisco; Garcia-Ruiz, Pedro Antonio; Varon, Ramon

    2012-01-01

    Highlights: ► The action the copper complexes and tyrosinase on phenols is equivalent. ► Isotope effect showed that nucleophilic attack to copper atom may be the slower step. ► The value of ρ (Hammett constant) supports an electrophilic aromatic substitution. ► Data obtained in steady state pH 7 conditions support the mechanism of Scheme 1SM. -- Abstract: A study of the monophenolase activity of tyrosinase by measuring the steady state rate with a group of p-substituted monophenols provides the following kinetic information: k cat m and the Michaelis constant, K M m . Analysis of these data taking into account chemical shifts of the carbon atom supporting the hydroxyl group (δ) and σ p + , enables a mechanism to be proposed for the transformation of monophenols into o-diphenols, in which the first step is a nucleophilic attack on the copper atom on the form E ox (attack of the oxygen of the hydroxyl group of C-1 on the copper atom) followed by an electrophilic attack (attack of the hydroperoxide group on the ortho position with respect to the hydroxyl group of the benzene ring, electrophilic aromatic substitution with a reaction constant ρ of −1.75). These steps show the same dependency on the electronic effect of the substituent groups in C-4. Furthermore, a study of a solvent deuterium isotope effect on the oxidation of monophenols by tyrosinase points to an appreciable isotopic effect. In a proton inventory study with a series of p-substituted phenols, the representation of k cat f n /k cat f 0 against n (atom fractions of deuterium), where k cat f n is the catalytic constant for a molar fraction of deuterium (n) and k cat f 0 is the corresponding kinetic parameter in a water solution, was linear for all substrates. These results indicate that only one of the proton transfer processes from the hydroxyl groups involved the catalytic cycle is responsible for the isotope effects. We suggest that this step is the proton transfer from the hydroxyl group

  8. A comparative study on the effect of solvent on nucleophilic fluorination with [18F]fluoride. Protic solvents as co-solvents in SN2 and SNAr reactions

    International Nuclear Information System (INIS)

    Koivula, T.; Simecek, J.; Jalomaeki, J.; Helariutta, K.; Airaksinen, A.J.

    2011-01-01

    The effect of solvent on nucleophilic substitution with cyclotron-produced [ 18 F]fluoride was studied in polar aprotic (CH 3 CN and DMF) and protic solvent (t-BuOH and t-amyl alcohol) mixtures (CH 3 CN/co-solvent, 2:8) in a series of model compounds, 4-(R 1 -methyl)benzyl R 2 -benzoates, using a K2.2.2/[ 18 F]KF phase transfer system (R 1 = -Cl, -OMs or -OH; R 2 = -Cl, -I or -NO 2 ). 18 F-fluorination of compounds 1-3, with chloride or mesylate as a leaving group in the benzylic position (R 1 ), afforded the desired 4-([ 18 F]fluoromethyl)benzyl analogues in all solvents during 15 min reaction time. The highest radiochemical yields (RCY) in all the studied reaction temperatures (80, 120 and 160 C) were achieved in CH 3 CN. Radiochemical yields in protic solvents were comparable to RCY in CH 3 CN only with the sulfonate ester 3 as a starting material. 18 F-Fluorination of the benzylic halides 1 and 2 was not promoted in the same extent; in addition, labelled side-products were detected at higher reaction temperatures. Radiofluorination in tert-alcohols was also studied using [ 18 F]CsF with and without added phase transfer catalyst, resulting in both conditions lower RCY when compared to K2.2.2/[ 18 F]KF system. Protic solvents were not able to promote aromatic 18 F-fluorination. 18 F-Fluorination of compound 5, having para-activated nitro group in the aromatic position (R 2 ), failed in tert-alcohols even at the highest temperature, but it was labelled successfully in DMF and to some extent in CH 3 CN. (orig.)

  9. Nucleophile-directed selectivity towards linear carbonates in the niobium pentaethoxide-catalysed cycloaddition of CO2 and propylene oxide

    KAUST Repository

    Dutta, Barnali

    2014-01-01

    Homoleptic Nb-complexes combined with selected organic nucleophiles generate very active catalytic systems for the cycloaddition of propylene oxide and CO2 under ambient conditions. An unprecedented reaction pathway towards an acyclic organic carbonate is observed when extending the study to [Nb(OEt)5] in combination with 4-dimethylamino-pyridine (DMAP) or tetra-n-butylammonium bromide (TBAB). Mechanistic insights of the reaction are provided based on experimental and spectroscopic evidences. This journal is © the Partner Organisations 2014.

  10. Synthesis and Structural Characterization of 1- and 2-Substituted Indazoles: Ester and Carboxylic Acid Derivatives

    Directory of Open Access Journals (Sweden)

    Isabel Bento

    2006-11-01

    Full Text Available A series of indazoles substituted at the N-1 and N-2 positions with ester-containing side chains -(CH2nCO2R of different lengths (n = 0-6, 9, 10 are described.Nucleophilic substitution reactions on halo esters (X(CH2nCO2R by 1H-indazole inalkaline solution lead to mixtures of N-1 and N-2 isomers, in which the N-1 isomerpredominates. Basic hydrolysis of the ester derivatives allowed the synthesis of thecorresponding indazole carboxylic acids. All compounds were fully characterised bymultinuclear NMR and IR spectroscopies, MS spectrometry and elemental analysis; theNMR spectroscopic data were used for structural assignment of the N-1 and N-2 isomers.The molecular structure of indazol-2-yl-acetic acid (5b was determined by X-raydiffraction, which shows a supramolecular architecture involving O2-H...N1intermolecular hydrogen bonds.

  11. Bone substitute biomaterials

    CERN Document Server

    Mallick, K

    2014-01-01

    Bone substitute biomaterials are fundamental to the biomedical sector, and have recently benefitted from extensive research and technological advances aimed at minimizing failure rates and reducing the need for further surgery. This book reviews these developments, with a particular focus on the desirable properties for bone substitute materials and their potential to encourage bone repair and regeneration. Part I covers the principles of bone substitute biomaterials for medical applications. One chapter reviews the quantification of bone mechanics at the whole-bone, micro-scale, and non-scale levels, while others discuss biomineralization, osteoductivization, materials to fill bone defects, and bioresorbable materials. Part II focuses on biomaterials as scaffolds and implants, including multi-functional scaffolds, bioceramics, and titanium-based foams. Finally, Part III reviews further materials with the potential to encourage bone repair and regeneration, including cartilage grafts, chitosan, inorganic poly...

  12. [Delegation yes, substitution no!].

    Science.gov (United States)

    Schroeder, A

    2014-08-01

    The aging of society leads on the one hand to increasing case numbers and on the other hand to a reduction in the number of physicians available for patient treatment. The delegation and substitution of medical duties as a tried and tested method is increasingly being recommended in order to compensate for the lack of physicians. The Berufsverband der Deutschen Urologen (BDU, Professional Association of German Urologists) supports the guiding principle of the Bundesärztekammer (Federal Medical Council) of "delegation yes, substitution no" and rejects a substitution of medical duties by non-medical academic health personnel. Against the background of the demographic changes, the increasing need for treatment and the current deficiency of junior physicians, a more extensive inclusion of well-qualified and experienced non-medical personnel by the delegation of medically responsible duties (medical scope of practice) can be an appropriate measure to maintain a good medical service in practices, hospitals and nursing homes.

  13. Aryl substitution of pentacenes

    Directory of Open Access Journals (Sweden)

    Andreas R. Waterloo

    2014-07-01

    Full Text Available A series of 11 new pentacene derivatives has been synthesized, with unsymmetrical substitution based on a trialkylsilylethynyl group at the 6-position and various aryl groups appended to the 13-position. The electronic and physical properties of the new pentacene chromophores have been analyzed by UV–vis spectroscopy (solution and thin films, thermoanalytical methods (DSC and TGA, cyclic voltammetry, as well as X-ray crystallography (for 8 derivatives. X-ray crystallography has been specifically used to study the influence of unsymmetrical substitution on the solid-state packing of the pentacene derivatives. The obtained results add to our ability to better predict substitution patterns that might be helpful for designing new semiconductors for use in solid-state devices.

  14. Aryl substitution of pentacenes

    Science.gov (United States)

    Waterloo, Andreas R; Sale, Anna-Chiara; Lehnherr, Dan; Hampel, Frank

    2014-01-01

    Summary A series of 11 new pentacene derivatives has been synthesized, with unsymmetrical substitution based on a trialkylsilylethynyl group at the 6-position and various aryl groups appended to the 13-position. The electronic and physical properties of the new pentacene chromophores have been analyzed by UV–vis spectroscopy (solution and thin films), thermoanalytical methods (DSC and TGA), cyclic voltammetry, as well as X-ray crystallography (for 8 derivatives). X-ray crystallography has been specifically used to study the influence of unsymmetrical substitution on the solid-state packing of the pentacene derivatives. The obtained results add to our ability to better predict substitution patterns that might be helpful for designing new semiconductors for use in solid-state devices. PMID:25161729

  15. Muon substituted free radicals

    International Nuclear Information System (INIS)

    Burkhard, P.; Fischer, H.; Roduner, E.; Strub, W.; Gygax, F.N.; Brinkman, G.A.; Louwrier, P.W.F.; McKenna, D.; Ramos, M.; Webster, B.C.

    1984-01-01

    Spin polarized energetic positive muons are injected as magnetic probes into unsaturated organic liquids. They are implemented via fast chemical processes ( -10 s) in various molecules. Of particular interest among these are muonium substituted free radicals. The technique allows determination of accurate rate coefficients for fast chemical reactions of radicals. Furthermore, radiochemical processes occuring in picoseconds after injection of the muon are studied. Of fundamental interest are also the structural and dynamical implications of substituting a proton by a muon, or in other terms, a hydrogen atom by a muonium atom. Selected examples for each of these three types of experiments are given. (Auth.)

  16. Theoretical study on the mechanism of the reaction of FOX-7 with OH and NO2 radicals: bimolecular reactions with low barrier during the decomposition of FOX-7

    Science.gov (United States)

    Zhang, Ji-Dong; Zhang, Li-Li

    2017-12-01

    The decomposition of 1,1-diamino-2,2-dinitroethene (FOX-7) attracts great interests, while the studies on bimolecular reactions during the decomposition of FOX-7 are scarce. This study for the first time investigated the bimolecular reactions of OH and NO2 radicals, which are pyrolysis products of ammonium perchlorate (an efficient oxidant usually used in solid propellant), with FOX-7 by computational chemistry methods. The molecular geometries and energies were calculated using the (U)B3LYP/6-31++G(d,p) method. The rate constants of the reactions were calculated by canonical variational transition state theory. We found three mechanisms (H-abstraction, OH addition to C and N atom) for the reaction of OH + FOX-7 and two mechanisms (O abstraction and H abstraction) for the reaction of NO2 + FOX-7. OH radical can abstract H atom or add to C atom of FOX-7 with barriers near to zero, which means OH radical can effectively degrade FOX-7. The O abstraction channel of the reaction of NO2 + FOX-7 results in the formation of NO3 radical, which has never been detected experimentally during the decomposition of FOX-7.

  17. Hazardous solvent substitution

    International Nuclear Information System (INIS)

    Twitchell, K.E.

    1995-01-01

    This article is an overview of efforts at INEL to reduce the generation of hazardous wastes through the elimination of hazardous solvents. To aid in their efforts, a number of databases have been developed and will become a part of an Integrated Solvent Substitution Data System. This latter data system will be accessible through Internet

  18. Carbolanthanation of substituted alkynes

    International Nuclear Information System (INIS)

    Kalinin, V.N.; Kazimirchuk, E.I.; Vitt, S.V.; Khandozhko, V.N.; Beletskaya, I.P.

    1993-01-01

    Using the reaction between CH 3 YbI and substituted alkynes as an example, agents can enter into carbolanthanation reaction via transfer of a methyl group to carbon atom of acetylene bond with the production of a new olefin carbanion. 5 refs.; 1 fig.; 3 tabs

  19. Exact substitute processes for diffusion-reaction systems with local complete exclusion rules

    International Nuclear Information System (INIS)

    Schulz, Michael; Reineker, Peter

    2005-01-01

    Lattice systems with one species diffusion-reaction processes under local complete exclusion rules are studied analytically starting from the usual master equations with discrete variables and their corresponding representation in a Fock space. On this basis, a formulation of the transition probability as a Grassmann path integral is derived in a straightforward manner. It will be demonstrated that this Grassmann path integral is equivalent to a set of Ito stochastic differential equations. Averages of arbitrary variables and correlation functions of the underlying diffusion-reaction system can be expressed as weighted averages over all solutions of the system of stochastic differential equations. Furthermore, these differential equations are equivalent to a Fokker-Planck equation describing the probability distribution of the actual Ito solutions. This probability distribution depends on continuous variables in contrast to the original master equation, and their stochastic dynamics may be interpreted as a substitute process which is completely equivalent to the original lattice dynamics. Especially, averages and correlation functions of the continuous variables are connected to the corresponding lattice quantities by simple relations. Although the substitute process for diffusion-reaction systems with exclusion rules has some similarities to the well-known substitute process for the same system without exclusion rules, there exists a set of remarkable differences. The given approach is not only valid for the discussed single-species processes. We give sufficient arguments to show that arbitrary combinations of unimolecular and bimolecular lattice reactions under complete local exclusions may be described in terms of our approach

  20. [Currently available skin substitutes].

    Science.gov (United States)

    Oravcová, Darina; Koller, Ján

    2014-01-01

    The current trend of burn wound care has shifted to more holistic approach of improvement in the long-term form and function of the healed burn wounds and quality of life. Autologous split or full-thickness skin graft are the best definitive burn wound coverage, but it is constrained by the limited available sources, especially in major burns. Donor site morbidities in term of additional wounds and scarring are also of concern of the autograft application. This has demanded the emergence of various skin substitutes in the management of acute burn injury as well as post burn reconstructions. This paper reviews currently available skin substitutes, produced in not for-profit skin banks as well as commercially available. They are divided according to type of material included, as biological, biosynthetic and synthetic and named respectively.

  1. Sparing the ortho-position in nucleophilic aromatic substitution-specific displacement of the 4-SePh group in 2,4-bis(phenylseleno)nitrobenzene

    DEFF Research Database (Denmark)

    Stuhr-Hansen, Nicolai; Götze, Thorstein Finn; Henriksen, Lars

    2009-01-01

    -ray crystallography, and DFT calculations. We found that the observed selectivity can be understood in terms of traditional resonance considerations. (C) 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:101-108, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20519...

  2. Aerobic Transition-Metal-Free Synthesis of 2,3-Diarylindoles and 5-Aryluracils via Oxidative Nucleophilic Substitution of Hydrogen Pathway

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Jin; Moon, Hye Ran; Kim, Su Yeon; Kim, Jae Nyoung [Chonnam National Un iversity, Gwangju (Korea, Republic of)

    2016-01-15

    2,3-diarylindoles and 5-aryluracils were synthesized by ONSH pathway under transition-metal-free conditions in good to moderate yields using molecular oxygen as an oxidant. As 2,3-diarylindoles have been found in many biologically important compounds, the synthesis of this scaffold has received much attention. Most frequently, 2,3-diarylindoles have been prepared via palladium-catalyzed arylations of 2-arylindole with bromoarenes. During our recent transition metal-catalyzed arylations of indoles and uracils, we were interested in the arylation in the absence of an expensive transition metal catalyst.

  3. Vicarious nucleophilic substitution to prepare 1,3-diamino-2,4,6-trinitrobenzene or 1,3,5-triamino-2,4,6-trinitrobenzene

    Science.gov (United States)

    Mitchell, Alexander R.; Pagoria, Philip F.; Schmidt, Robert D.

    1996-01-01

    The present invention relates to a process to produce 1,3-diamino-2,4,6-trinitrobenzene (DATB) or 1,3,5-triamino-2,4,6,-trinitrobenzene (TATB) by: (a) reacting at ambient pressure and a temperature of between about 0.degree. and 50.degree. C. for between about 0.1 and 24 hr, a trinitroaromatic compound of structure V: ##STR1## wherein X, Y, and Z are each independently selected from --H, or --NH.sub.2, with the proviso that at least 1 or 2 of X, Y, and Z are hydrogen, with an amount effective to produce DATB or TATB of 1,1,1-trialkylhydrazinium halide wherein alkyl is selected from methyl, ethyl, propyl or butyl and halide is selected from chloride, bromide or iodide. in the presence of a strong base selected from sodium butoxide, potassium butoxide, potassium propoxide, sodium propoxide, sodium ethoxide, potassium ethoxide, sodium methoxide, potassium methoxide, and combinations thereof; in a solvent selected from the group consisting of methanol, ethanol, propanol, butanol, dimethylsulphoxide, N-methylpyrrolidone, hexamethylphosphoramide, dimethylformide, dimethylacetamide and mixtures thereof, provided that when alcohols are present primarily DATB and picramide is formed; and (b) isolating the DATB or TATB produced. DATB and TATB are useful specialty explosives. TATB is also used for the preparation of benzenehexamine, a starting material for the synthesis of novel materials (optical imaging devices, liquid crystals, ferromagnetic compounds).

  4. Unraveling the role of entropy in tuning unimolecular vs . bimolecular reaction rates: The case of olefin polymerization catalyzed by transition metals

    KAUST Repository

    Falivene, Laura

    2018-04-24

    Olefin polymerization catalyzed by Group 4 transition metals is studied here as test case to reveal the entropy effects when bimolecular and unimolecular reactions are computed for processes occurring in solution. Catalytic systems characterized by different ligand frameworks, metal, and growing polymeric chain for which experimental data are available have been selected in order to validate the main approaches to entropy calculation. Applying the “standard” protocol results in a strong disagreement with the experimental results and the methods introducing a direct correction of the translational entropy term based on a single experimental parameter emerge as the most reliable. The general and powerful computational tool achieved in this study can represent a further step towards the “catalyst design” to control and predict the molecular mass of the resulting polymers.

  5. In vitro and in vivo mapping of the Prunus necrotic ringspot virus coat protein C-terminal dimerization domain by bimolecular fluorescence complementation.

    Science.gov (United States)

    Aparicio, Frederic; Sánchez-Navarro, Jesús A; Pallás, Vicente

    2006-06-01

    Interactions between viral proteins are critical for virus viability. Bimolecular fluorescent complementation (BiFC) technique determines protein interactions in real-time under almost normal physiological conditions. The coat protein (CP) of Prunus necrotic ringspot virus is required for multiple functions in its replication cycle. In this study, the region involved in CP dimerization has been mapped by BiFC in both bacteria and plant tissue. Full-length and C-terminal deleted forms of the CP gene were fused in-frame to the N- and C-terminal fragments of the yellow fluorescent protein. The BiFC analysis showed that a domain located between residues 9 and 27 from the C-end plays a critical role in dimerization. The importance of this C-terminal region in dimer formation and the applicability of the BiFC technique to analyse viral protein interactions are discussed.

  6. The influence of the "cage" effect on the mechanism of reversible bimolecular multistage chemical reactions proceeding from different sites in solutions.

    Science.gov (United States)

    Doktorov, Alexander B

    2016-08-28

    Manifestations of the "cage" effect at the encounters of reactants have been theoretically treated on the example of multistage reactions (including bimolecular exchange reactions as elementary stages) proceeding from different active sites in liquid solutions. It is shown that for reactions occurring near the contact of reactants, consistent consideration of quasi-stationary kinetics of such multistage reactions (possible in the framework of the encounter theory only) can be made on the basis of chemical concepts of the "cage complex," just as in the case of one-site model described in the literature. Exactly as in the one-site model, the presence of the "cage" effect gives rise to new channels of reactant transformation that cannot result from elementary event of chemical conversion for the given reaction mechanism. Besides, the multisite model demonstrates new (as compared to one-site model) features of multistage reaction course.

  7. Synthesis and application of aryl-ferrocenyl(pseudo-biarylic) complexes. Part 5. Design and synthesis of a new type of ferrocene-based planar chiral DMAP analogues. A new catalyst system for asymmetric nucleophilic catalysis

    DEFF Research Database (Denmark)

    Seitzberg, J.G; Dissing, C; Søtofte, Inger

    2005-01-01

    A new first-generation catalyst system for nucleophilic catalysis has been developed. It is based on a planar chiral ferrocene skeleton with either the potent nucleophile 4-(dimethylamino)pyridine (DMAP) or the related 4-nitropyridine N-oxide attached in either the 2- or the 3-position. The synth......A new first-generation catalyst system for nucleophilic catalysis has been developed. It is based on a planar chiral ferrocene skeleton with either the potent nucleophile 4-(dimethylamino)pyridine (DMAP) or the related 4-nitropyridine N-oxide attached in either the 2- or the 3-position...

  8. Fine-tuning the nucleophilic reactivities of boron ate complexes derived from aryl and heteroaryl boronic esters.

    Science.gov (United States)

    Berionni, Guillaume; Leonov, Artem I; Mayer, Peter; Ofial, Armin R; Mayr, Herbert

    2015-02-23

    Boron ate complexes derived from thienyl and furyl boronic esters and aryllithium compounds have been isolated and characterized by X-ray crystallography. Products and mechanisms of their reactions with carbenium and iminium ions have been analyzed. Kinetics of these reactions were monitored by UV/Vis spectroscopy, and the influence of the aryl substituents, the diol ligands (pinacol, ethylene glycol, neopentyl glycol, catechol), and the counterions on the nucleophilic reactivity of the boron ate complexes were examined. A Hammett correlation confirmed the polar nature of their reactions with benzhydrylium ions, and the correlation lg k(20 °C)=sN (E+N) was employed to determine the nucleophilicities of the boron ate complexes and to compare them with those of other borates and boronates. The neopentyl and ethylene glycol derivatives were found to be 10(4) times more reactive than the pinacol and catechol derivatives. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Hexavalent Chromium Substitution Projects

    Science.gov (United States)

    2011-05-12

    Hexavalent Chromium Substitution Projects Date (12 May 2011) Gene McKinley ASC/WNV (937) 255-3596 Gene.McKinley@wpafb.af.mil Aeronautical Systems...valid OMB control number. 1. REPORT DATE 12 MAY 2011 2. REPORT TYPE 3. DATES COVERED 00-00-2011 to 00-00-2011 4. TITLE AND SUBTITLE Hexavalent ...A-10) – AETC (T-6, T-38 and T1A) • Both Cr Primers & Non-Cr primers as well as Cr Surface Treatment – F-22 8 Non- Chrome Tie-coat & touch-up

  10. Muonium substituted molecules

    International Nuclear Information System (INIS)

    Cox, S.F.J.

    1990-12-01

    The manner in which Muon Spin Rotation and Level Crossing Resonance are used to characterise muonium substituted organic radicals is described, and illustrated with spectra for the ethyl radical and related species. Comparison with electron spin resonance data for the unsubstituted radicals reveals significant structural and hyperfine isotope effects which can be traced to the effects of zero point motion. The first comparable results for a diamagnetic species, exhibiting a quadrupole isotope effect by comparison with conventional nuclear quadrupole resonance data, are presented and discussed. (author)

  11. Acid dissociation constant and apparent nucleophilicity of lysine-501 of the alpha-polypeptide of sodium and potassium ion activated adenosinetriphosphatase

    International Nuclear Information System (INIS)

    Xu, K.Y.

    1989-01-01

    A combination of competitive labeling with [ 3 H]acetic anhydride and immunoaffinity chromatography is described that permits the assignment of the acid dissociation constant and the absolute nucleophilicity of individual lysines in a native enzyme. The acid dissociation constant of lysine-501 of the alpha-polypeptide in native (Na+ + K+)-ATPase was determined. This lysine had a normal pKa of 10.4. The rate constant for the reaction of the free base of lysine-501 with acetic anhydride at 10 degrees C is 400 M-1 s-1. This value is only 30% that for a fully accessible lysine in a protein. The lower than normal apparent nucleophilicity suggests that lysine-501 is hindered from reacting with its intrinsic nucleophilicity by the tertiary structure of the enzyme and is consistent with its location within a pocket that forms the active site upon the surface of the native protein

  12. Resources, recycle, and substitution

    International Nuclear Information System (INIS)

    Wymer, R.G.

    A two-fold strategy appears necessary to ensure that the resource needs of the developed and developing nations are met. First, recycle and substitution must be encouraged in those instances where they do find application. Although these measures have limited applicability, they may be of vital importance in those instances where they do apply; in any event, they buy time. Second, practical and economical technologies must be developed to exploit the lower-grade and marginal ores and the oftentimes abundant but highly refractory ores, as well as to greatly increase the recovery of secondary elements present in the ores - elements whose form and amounts in the ores make them economically unrecoverable by themselves, but which are economically recoverable as by-products. It is often the case that if these elements are not recovered during the initial mining and milling operations, they are rendered unrecoverable, in a practical sense, forever. Furthermore, they may even become environmental pollutants. Specific examples of recovery from refractory ores, by-product recovery, and recycle are given. Also, some suggestions of substitutes for important resources are tabulated

  13. Living Polymerization of N -Substituted β-Alanine N -Carboxyanhydrides: Kinetic Investigations and Preparation of an Amphiphilic Block Copoly-β-Peptoid

    KAUST Repository

    Grossmann, Arlett

    2012-07-03

    Poly(α-peptoid)s (N-substituted polyglycines) are interesting peptidomimetic biomaterials that have been discussed for many applications. Poly(β-peptoid)s (N-substituted poly-β-alanines), although equally intriguing, have received much less attention. Here we present results that suggest that while N-substituted β-alanine N-carboxyanhydrides can undergo a living nucleophilic ring-opening polymerization, the solubility of poly(β-peptoid)s can be very poor, which contributes to the limited accessibility using other synthetic approaches. The living character of the polymerization was utilized for the preparation of the first polymerized amphiphilic block copoly-β-peptoid. Our results may open a new route towards highly defined functional poly(β-peptoid)s which could represent biomaterials. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Glycosyl Cross-Coupling of Anomeric Nucleophiles: Scope, Mechanism, and Applications in the Synthesis of Aryl C-Glycosides.

    Science.gov (United States)

    Zhu, Feng; Rodriguez, Jacob; Yang, Tianyi; Kevlishvili, Ilia; Miller, Eric; Yi, Duk; O'Neill, Sloane; Rourke, Michael J; Liu, Peng; Walczak, Maciej A

    2017-12-13

    Stereoselective manipulations at the C1 anomeric position of saccharides are one of the central goals of preparative carbohydrate chemistry. Historically, the majority of reactions forming a bond with anomeric carbon has focused on reactions of nucleophiles with saccharide donors equipped with a leaving group. Here, we describe a novel approach to stereoselective synthesis of C-aryl glycosides capitalizing on the highly stereospecific reaction of anomeric nucleophiles. First, methods for the preparation of anomeric stannanes have been developed and optimized to afford both anomers of common saccharides in high anomeric selectivities. We established that oligosaccharide stannanes could be prepared from monosaccharide stannanes via O-glycosylation with Schmidt-type donors, glycal epoxides, or under dehydrative conditions with C1 alcohols. Second, we identified a general set of catalytic conditions with Pd 2 (dba) 3 (2.5 mol%) and a bulky ligand (JackiePhos, 10 mol%) controlling the β-elimination pathway. We demonstrated that the glycosyl cross-coupling resulted in consistently high anomeric selectivities for both anomers with mono- and oligosaccharides, deoxysugars, saccharides with free hydroxyl groups, pyranose, and furanose substrates. The versatility of the glycosyl cross-coupling reaction was probed in the total synthesis of salmochelins (siderophores) and commercial anti-diabetic drugs (gliflozins). Combined experimental and computational studies revealed that the β-elimination pathway is suppressed for biphenyl-type ligands due to the shielding of Pd(II) by sterically demanding JackiePhos, whereas smaller ligands, which allow for the formation of a Pd-F complex, predominantly result in a glycal product. Similar steric effects account for the diminished rates of cross-couplings of 1,2-cis C1-stannanes with aryl halides. DFT calculations also revealed that the transmetalation occurs via a cyclic transition state with retention of configuration at the anomeric

  15. Iminoboronate Formation Leads to Fast and Reversible Conjugation Chemistry of α-Nucleophiles at Neutral pH.

    Science.gov (United States)

    Bandyopadhyay, Anupam; Gao, Jianmin

    2015-10-12

    Bioorthogonal reactions that are fast and reversible under physiological conditions are in high demand for biological applications. Herein, it is shown that an ortho boronic acid substituent makes aryl ketones rapidly conjugate with α-nucleophiles at neutral pH. Specifically, 2-acetylphenylboronic acid and derivatives were found to conjugate with phenylhydrazine with rate constants of 10(2) to 10(3) M(-1) s(-1) , comparable to the fastest bioorthogonal conjugations known to date. (11) B NMR analysis revealed the varied extent of iminoboronate formation of the conjugates, in which the imine nitrogen forms a dative bond with boron. The iminoboronate formation activates the imines for hydrolysis and exchange, rendering these oxime/hydrazone conjugations reversible and dynamic under physiological conditions. The fast and dynamic nature of the iminoboronate chemistry should find wide applications in biology. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Picosecond real time study of the bimolecular reaction O(3P)+C2H4 and the unimolecular photodissociation of CH3CHO and H2CO

    Science.gov (United States)

    Abou-Zied, Osama K.; McDonald, J. Douglas

    1998-07-01

    The bimolecular reaction of O(3P) with ethylene and the unimolecular photodissociation of acetaldehyde and formaldehyde have been studied using a picosecond pump/probe technique. The bimolecular reaction was initiated in a van der Waals dimer precursor, C2H4ṡNO2, and the evolution of the vinoxy radical product monitored by laser-induced fluorescence. The NO2 constituent of the complex was photodissociated at 266 nm. The triplet oxygen atom then attacks a carbon atom of C2H4 to form a triplet diradical (CH2CH2O) which subsequently dissociates to vinoxy (CH2CHO) and H. The rise time of vinoxy radical production was measured to be 217 (+75-25) ps. RRKM theory was applied and a late high exit barrier was invoked in order to fit the measured rise time. The structure and binding energy of the van der Waals complex have been modeled using Lennard-Jones type potentials and the results were compared with other systems. The unimolecular side of the potential energy surfaces of this reaction has been investigated by photodissociating acetaldehyde at the same pump energy of 266 nm. The resulting photoproducts, acetyl radical (CH3CO) and formyl radical (HCO), have been monitored by resonance enhanced multiphoton ionization (REMPI) combined with a time-of-flight mass spectrometer. The similarity in the measured evolution times of both radicals indicates the same photodissociation pathway of the parent molecule. The photodissociation rate of acetaldehyde is estimated from RRKM theory to be very fast (3×1012s-1). The T1←S1 intersystem crossing (ISC) rate is found to be the rate determining step to photodissociation and increases with energy. The REMPI mechanism for the production of CH3CO+ is proposed to be the same as that of HCO+(2+1). The HCO product from the photodissociation of formaldehyde at 266 nm reveals a faster T1←S1 ISC rate than in acetaldehyde.

  17. A theoretical quantum study on the distribution of electrophilic and nucleophilic active sites on Cu(100) surfaces modeled as finite clusters

    International Nuclear Information System (INIS)

    Rios R, C.H.; Romero R, M.; Ponce R, A.; Mendoza H, L.H.

    2008-01-01

    In this work, it is shown a theoretical quantum study of the active sites distribution on a monocrystalline surface of Cu(100). The copper surface was modeled as finite clusters of 14, 23, 38 and 53 atoms. We performed Hartree-Fock and Density Functional Theory (B3LYP) ab initio calculations employing the pseudopotentials of Hay and Wadt (LANLlMB y LANL2DZ). From calculations, we found a work function value of 4.1 eV. The mapping of the HOMO and LUMO in the frozen core approximation, allowed us finding the electrophilic and nucleophilic active sites distribution, respectively. The results indicated that electrophilic sites on the Cu(100) surface were located on hollow position and its numerical density was 8.6 x 10 16 sites cm -2 . From the nucleophilic local softness study, it was found that the nucleophilic sites were formed by a group of atoms and it had a numerical density of 2.4x 10 16 sitescm -2 . Last results indicated that adsorptions with 2 x 2 and 3 x 3 distributions can be favored onto a Cu(100) surface for the electrophilic and nucleophilic cases, respectively. (Author)

  18. Stereocontrolled generation of nucleophilic (Z)- or (E)-α-fluoroalkenylchromium reagents via carbon-fluorine bond activation: highly stereoselective synthesis of (E)- or (Z)-β-fluoroallylic alcohols.

    Science.gov (United States)

    Nihei, Takashi; Yokotani, Saya; Ishihara, Takashi; Konno, Tsutomu

    2014-02-14

    Highly nucleophilic (Z)- or (E)-α-fluoroalkenylchromium species could be generated in a stereoselective manner via C-F bond activation of CBrF2-containing molecules, and they reacted smoothly with various aldehydes to give (E)- or (Z)-β-fluoroallylic alcohol derivatives in high yields, respectively.

  19. Origin of Enhanced Reactivity of a Microsolvated Nucleophile in Ion Pair SN2 Reactions: The Cases of Sodium p-Nitrophenoxide with Halomethanes in Acetone.

    Science.gov (United States)

    Li, Qiang-Gen; Xu, Ke; Ren, Yi

    2015-04-30

    In a kinetic experiment on the SN2 reaction of sodium p-nitrophenoxide with iodomethane in acetone-water mixed solvent, Humeres et al. (J. Org. Chem. 2001, 66, 1163) found that the reaction depends strongly on the medium, and the fastest rate constant was observed in pure acetone. The present work tries to explore why acetone can enhance the reactivity of the title reactions. Accordingly, we make a mechanistic study on the reactions of sodium p-nitrophenoxide with halomethanes (CH3X, X = Cl, Br, I) in acetone by using a supramolecular/continuum model at the PCM-MP2/6-311+G(d,p)//B3LYP/6-311+G(d,p) level, in which the ion pair nucleophile is microsolvated by one to three acetone molecules. We compared the reactivity of the microsolvated ion pair nucleophiles with solvent-free ion pair and anionic ones. Our results clearly reveal that the microsolvated ion pair nucleophile is favorable for the SN2 reactions; meanwhile, the origin of the enhanced reactivity induced by microsolvation of the nucleophile is discussed in terms of the geometries of transition state (TS) structures and activation strain model, suggesting that lower deformation energies and stronger interaction energies between the deformed reactants in the TS lead to the lower overall reaction barriers for the SN2 reaction of microsolvated sodium p-nitrophenoxide toward halomethanes in acetone.

  20. Currency substitution in Eastern Europe

    NARCIS (Netherlands)

    van Aarle, B.; Budina, N.

    1995-01-01

    Monetary instability during the transition process from a command economy to a market economy has induced a considerable increase in currency substitution in Eastern Europe. Currency substitution itself affects monetary stability since it reduces the stability of velocity. This paper investigates

  1. Why Does Trigonometric Substitution Work?

    Science.gov (United States)

    Cunningham, Daniel W.

    2018-01-01

    Modern calculus textbooks carefully illustrate how to perform integration by trigonometric substitution. Unfortunately, most of these books do not adequately justify this powerful technique of integration. In this article, we present an accessible proof that establishes the validity of integration by trigonometric substitution. The proof offers…

  2. Substitution of matrices over rings

    NARCIS (Netherlands)

    Hautus, M.L.J.

    1995-01-01

    For a given commutative ring with an identity element, we define and study the substitution of a matrix with entries in into a matrix polynomial or rational function over . A Bezout-type remainder theorem and a "partial-substitution rule" are derived and used to obtain a number of results. The

  3. Substitution in recreation choice behavior

    Science.gov (United States)

    George L. Peterson; Daniel J. Stynes; Donald H. Rosenthal; John F. Dwyer

    1985-01-01

    This review discusses concepts and theories of substitution in recreation choice. It brings together the literature of recreation research, psychology, geography, economics, and transportation. Parallel and complementary developments need integration into an improved theory of substitution. Recreation decision behavior is characterized as a nested or sequential choice...

  4. Biological background of dermal substitutes

    NARCIS (Netherlands)

    van der Veen, V. C.; van der Wal, M.B.; van Leeuwen, M.C.; Ulrich, M.; Middelkoop, E.

    2010-01-01

    Dermal substitutes are of major importance in treating full thickness skin defects, both in acute and chronic wounds. In this review we will outline specific requirements of three classes of dermal substitutes:-natural biological materials, with a more or less intact extracellular matrix

  5. Probing the reactivation process of sarin-inhibited acetylcholinesterase with α-nucleophiles: hydroxylamine anion is predicted to be a better antidote with DFT calculations.

    Science.gov (United States)

    Khan, Md Abdul Shafeeuulla; Lo, Rabindranath; Bandyopadhyay, Tusar; Ganguly, Bishwajit

    2011-08-01

    Inactivation of acetylcholinesterase (AChE) due to inhibition by organophosphorus (OP) compounds is a major threat to human since AChE is a key enzyme in neurotransmission process. Oximes are used as potential reactivators of OP-inhibited AChE due to their α-effect nucleophilic reactivity. In search of more effective reactivating agents, model studies have shown that α-effect is not so important for dephosphylation reactions. We report the importance of α-effect of nucleophilic reactivity towards the reactivation of OP-inhibited AChE with hydroxylamine anion. We have demonstrated with DFT [B3LYP/6-311G(d,p)] calculations that the reactivation process of sarin-serine adduct 2 with hydroxylamine anion is more efficient than the other nucleophiles reported. The superiority of hydroxylamine anion to reactivate the sarin-inhibited AChE with sarin-serine adducts 3 and 4 compared to formoximate anion was observed in the presence and absence of hydrogen bonding interactions of Gly121 and Gly122. The calculated results show that the rates of reactivation process of adduct 4 with hydroxylamine anion are 261 and 223 times faster than the formoximate anion in the absence and presence of such hydrogen bonding interactions. The DFT calculated results shed light on the importance of the adjacent carbonyl group of Glu202 for the reactivation of sarin-serine adduct, in particular with formoximate anion. The reverse reactivation reaction between hydroxylamine anion and sarin-serine adduct was found to be higher in energy compared to the other nucleophiles, which suggests that this α-nucleophile can be a good antidote agent for the reactivation process. Copyright © 2011 Elsevier Inc. All rights reserved.

  6. Live cell imaging of interactions between replicase and capsid protein of Brome mosaic virus using Bimolecular Fluorescence Complementation: implications for replication and genome packaging.

    Science.gov (United States)

    Chaturvedi, Sonali; Rao, A L N

    2014-09-01

    In Brome mosaic virus, it was hypothesized that a physical interaction between viral replicase and capsid protein (CP) is obligatory to confer genome packaging specificity. Here we tested this hypothesis by employing Bimolecular Fluorescent Complementation (BiFC) as a tool for evaluating protein-protein interactions in living cells. The efficacy of BiFC was validated by a known interaction between replicase protein 1a (p1a) and protein 2a (p2a) at the endoplasmic reticulum (ER) site of viral replication. Additionally, co-expression in planta of a bona fide pair of interacting protein partners of p1a and p2a had resulted in the assembly of a functional replicase. Subsequent BiFC assays in conjunction with mCherry labeled ER as a fluorescent cellular marker revealed that CP physically interacts with p2a, but not p1a, and this CP:p2a interaction occurs at the cytoplasmic phase of the ER. The significance of the CP:p2a interaction in BMV replication and genome packaging is discussed. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Live cell imaging of interactions between replicase and capsid protein of Brome mosaic virus using Bimolecular Fluorescence Complementation: Implications for replication and genome packaging

    International Nuclear Information System (INIS)

    Chaturvedi, Sonali; Rao, A.L.N.

    2014-01-01

    In Brome mosaic virus, it was hypothesized that a physical interaction between viral replicase and capsid protein (CP) is obligatory to confer genome packaging specificity. Here we tested this hypothesis by employing Bimolecular Fluorescent Complementation (BiFC) as a tool for evaluating protein–protein interactions in living cells. The efficacy of BiFC was validated by a known interaction between replicase protein 1a (p1a) and protein 2a (p2a) at the endoplasmic reticulum (ER) site of viral replication. Additionally, co-expression in planta of a bona fide pair of interacting protein partners of p1a and p2a had resulted in the assembly of a functional replicase. Subsequent BiFC assays in conjunction with mCherry labeled ER as a fluorescent cellular marker revealed that CP physically interacts with p2a, but not p1a, and this CP:p2a interaction occurs at the cytoplasmic phase of the ER. The significance of the CP:p2a interaction in BMV replication and genome packaging is discussed. - Highlights: • YFP fusion proteins of BMV p1a and p2a are biologically active. • Self-interaction was observed for p1a, p2a and CP. • CP interacts with p2a but not p1a. • Majority of reconstituted YFP resulting from bona fide fusion protein partners localized on ER

  8. Live cell imaging of interactions between replicase and capsid protein of Brome mosaic virus using Bimolecular Fluorescence Complementation: Implications for replication and genome packaging

    Energy Technology Data Exchange (ETDEWEB)

    Chaturvedi, Sonali; Rao, A.L.N., E-mail: arao@ucr.edu

    2014-09-15

    In Brome mosaic virus, it was hypothesized that a physical interaction between viral replicase and capsid protein (CP) is obligatory to confer genome packaging specificity. Here we tested this hypothesis by employing Bimolecular Fluorescent Complementation (BiFC) as a tool for evaluating protein–protein interactions in living cells. The efficacy of BiFC was validated by a known interaction between replicase protein 1a (p1a) and protein 2a (p2a) at the endoplasmic reticulum (ER) site of viral replication. Additionally, co-expression in planta of a bona fide pair of interacting protein partners of p1a and p2a had resulted in the assembly of a functional replicase. Subsequent BiFC assays in conjunction with mCherry labeled ER as a fluorescent cellular marker revealed that CP physically interacts with p2a, but not p1a, and this CP:p2a interaction occurs at the cytoplasmic phase of the ER. The significance of the CP:p2a interaction in BMV replication and genome packaging is discussed. - Highlights: • YFP fusion proteins of BMV p1a and p2a are biologically active. • Self-interaction was observed for p1a, p2a and CP. • CP interacts with p2a but not p1a. • Majority of reconstituted YFP resulting from bona fide fusion protein partners localized on ER.

  9. Bimolecular interaction of argpyrimidine (a Maillard reaction product) in in vitro non-enzymatic protein glycation model and its potential role as an antiglycating agent.

    Science.gov (United States)

    Bhattacherjee, Abhishek; Dhara, Kaliprasanna; Chakraborti, Abhay Sankar

    2017-09-01

    Non- enzymatic glycation, also known as Maillard reaction, is one of the most important and investigated reactions in biochemistry. Maillard reaction products (MRPs) like protein-derived advanced glycation end products (AGEs) are often referred to cause pathophysiological complications in human systems. On contrary, several MRPs are exogenously used as antioxidant, antimicrobial and flavouring agents. In the preset study, we have shown that argpyrimidine, a well-established AGE, interacts with bovine serum albumin (BSA) and glucose individually in standard BSA-glucose model system and successfully inhibits glycation of the protein. Bimolecular interaction of argpyrimidine with glucose or BSA has been studied independently. Chromatographic purification, different spectroscopic studies and molecular modeling have been used to evaluate the nature and pattern of interactions. Binding of argpyrimidine with BSA prevents incorporation of glucose inside the native protein. Argpyrimidine can also directly entrap glucose. Both these interactions may be associated with the antiglycation potential of argpyrimidine, indicating a beneficial function of an AGE. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Syntheses and biological activities of 13-substituted avermectin aglycons.

    Science.gov (United States)

    Mrozik, H; Linn, B O; Eskola, P; Lusi, A; Matzuk, A; Preiser, F A; Ostlind, D A; Schaeffer, J M; Fisher, M H

    1989-02-01

    The reactions of sulfonate esters of the allylic/homoallylic 13-alcohol of 5-O-(tert-butyldimethylsilyl)-22,23-dihydroavermectin B1a aglycon (1a) were investigated. Nucleophilic substitution gave 13 beta-chloro and 13 beta-iodo derivatives, while solvolytic reaction conditions yielded 13 alpha-methoxy, 13 alpha-fluoro, and 13 alpha-chloro products. A mixture of 13 alpha- and 13 beta-fluorides was obtained upon reaction with DAST. The 13 beta-iodide gave, upon elimination with lutidine, the 8(9),10(11),12(13),14(15)-tetraene. The 13 beta-alcohol and the rearranged 15-ol 13(14)-ene and 15-amino 13(14)-ene derivatives were obtained by substitution via the allylic carbonium ion. MEM ethers 11 and 12 of the two epimeric 13-ols were prepared by alkylation with MEM chloride. In contrast, methylation of 1a with MeI and Ag2O in CH2Cl2 occurred exclusively at the tertiary 7-hydroxy group and not at the secondary 13 alpha-ol. Oxidation of the allylic alcohol 1a proceeded under Swern conditions but not with MnO2 to the 13-oxo aglycon, which was reduced by NaBH4 exclusively to the natural 13 alpha-ol, while reductive amination with NaCNBH3-NH4OAc gave the 13 alpha-amine. The methoxime derivative was obtained in the form of the two geometric isomers. Anthelmintic activities against the sheep nematode Trichostrongylus colubriformis, miticidal activities against the two-spotted spider mite (Tetranychus urticae), and insecticidal activities against the southern armyworm (Spodoptera eridania) as well as the binding constants to a free living nematode (Caenorhabditis elegans) derived receptor assay were obtained and compared to avermectin B1a, 22,23-dihydroavermectin B1a, and the 13-deoxy-22,23-dihydroavermectin B1 aglycon related to the milbemycins. None of the newly prepared derivatives exceeded the potency of the three reference compounds. Lipophilic 13-substituents such as halogen, alkoxy, and methoxime retained high biological activities in all assays, while the more polar

  11. N-substituted iminodiacetic acids

    International Nuclear Information System (INIS)

    Nunn, A.; Loberg, M.

    1982-01-01

    The chemical preparation of several new N-substituted iminodiacetic acid derivatives are described. These compounds when complexed with sup(99m)Tc provide useful radiopharmaceuticals for the external imaging of the hepatobiliary system. (U.K.)

  12. Commercial formalin substitutes for histopathology

    DEFF Research Database (Denmark)

    Prentø, P; Lyon, H

    1997-01-01

    We compared the performance of six commercial fixatives proposed to be formalin substitutes with the performance of buffered formalin, Clarke's ethanol-acetic acid, and ethanol, using rat liver, small intestine, and kidney. We investigated the rate of penetration, mode of fixation, extent of prot...... was obtained by combining formalin fixation with antigen retrieval. We conclude that none of the proposed commercial substitutes for buffered formalin are adequate for critical histology or histopathology....

  13. Stores, Prices, and Currency Substitution

    OpenAIRE

    Gabriele, Camera; Winkler, Johannes

    1999-01-01

    We study endogenous currency substitution in a decentralized trade environment. Sellers maximize profits from sales of imperfectly substitutable goods by posting prices in either one of two currencies. A unique symmetric equilibrium exists where goods are priced only in the local currency. This occurs if foreign trade is sporadic, there is sufficient but not excessive liquidity, and discounting is low. Excess or scarcity of liquidity, however, induces sellers to extract all surplus from bu...

  14. Substitution reactions of technetium complexes

    International Nuclear Information System (INIS)

    Omori, T.

    1997-01-01

    Substitution reactions of a series of technetium complexes are considered in comparison with corresponding reactions of rhenium. Rhenium and technetium complexes are rather inert in substitution reactions, the latter are characterized by greater rate constants when they proceed according to dissociative mechanism. In rare cases when k Tc /k Re id little it is assumed that the reaction proceeds according to the associative mechanism. (author)

  15. Synthesis of carbasugars from aldonolactones, part III - A study on the allylic substitution of (1R,5R,8R)- and (1R,5R,8S)-8-hydroxy-2-oxabicyclo[3.3.0]oct-6-en-3-one derivatives - Preparation of (1S,2R,3R)-9-[2-hydroxy-3-(2-hydroxyethyl)cyclopent-4-en-1-yl]-9H-adenine

    DEFF Research Database (Denmark)

    Johansen, Steen Karsk; Lundt, Inge

    2001-01-01

    The palladium-catalyzed substitution of acylated (1R,5R,8R)- and (1R,SR,8S)-8-hydroxy-2-oxabicyclo[3.3.0] ones has been studied using a number of C- and N-nucleophiles, In all cases, the exo derivatives (8R) were found to be more reactive than the corresponding endo derivatives (8S). The reaction...... with these nucleophiles. Additionally, Mitsunobu substitution of (1R,5R,8R)-8-hydroxy-2-oxabicyclo[3.3.0]oct-B-en-3-one (3) with 6-chloropurine, followed by reduction of the lactone moiety and treatment with Liquid ammonia, gave the carbocyclic nucleoside (1S,2R,3R)-9-[2-hydroxy-3-(2-hydroxyethyl)cyclopent-4-en-1-yl]-9H...

  16. Radiation chemistry of salicylic and methyl substituted salicylic acids: Models for the radiation chemistry of pharmaceutical compounds

    International Nuclear Information System (INIS)

    Ayatollahi, Shakiba; Kalnina, Daina; Song, Weihua; Turks, Maris; Cooper, William J.

    2013-01-01

    Salicylic acid and its derivatives are components of many medications and moieties found in numerous pharmaceutical compounds. They have been used as models for various pharmaceutical compounds in pharmacological studies, for the treatment of pharmaceuticals and personal care products (PPCPs), and, reactions with natural organic matter (NOM). In this study, the radiation chemistry of benzoic acid, salicylic acid and four methyl substituted salicylic acids (MSA) is reported. The absolute bimolecular reaction rate constants for hydroxyl radical reaction with benzoic and salicylic acids as well as 3-methyl-, 4-methyl-, 5-methyl-, and 6-methyl-salicylic acid were determined (5.86±0.54)×10 9 , (1.07±0.07)×10 10 , (7.48±0.17)×10 9 , (7.31±0.29)×10 9 , (5.47±0.25)×10 9 , (6.94±0.10)×10 9 (M −1 s −1 ), respectively. The hydrated electron reaction rate constants were measured (3.02±0.10)×10 9 , (8.98±0.27)×10 9 , (5.39±0.21)×10 9 , (4.33±0.17)×10 9 , (4.72±0.15)×10 9 , (1.42±0.02)×10 9 (M −1 s −1 ), respectively. The transient absorption spectra for the six model compounds were examined and their role as model compounds for the radiation chemistry of pharmaceuticals investigated. - Highlights: • Free radical chemistry of salicylic and 4 methyl salicylic acids is investigated. • The transient absorptions spectra for model compounds are measured. • Absolute bimolecular reaction rate constants for hydroxyl radical are determined. • Solvated electron reaction rate constants are calculated. • The use of salicylic acids as models for pharmaceuticals is explored

  17. Electrochemical and Spin-Trapping Properties of para-substituted α-Phenyl-N-tert-butyl Nitrones

    International Nuclear Information System (INIS)

    Rosselin, Marie; Tuccio, Béatrice; Pério, Pierre; Villamena, Frederick A.; Fabre, Paul-Louis; Durand, Grégory

    2016-01-01

    Nitrones are known both as therapeutic antioxidants and efficient spin-traps. In this work, the redox behavior of various para-substituted α-phenyl-N-tert-butyl nitrones (PBN) was studied by cyclic voltammetry. The polar effect of the substituents was found to correlate with the electrochemical properties of the nitronyl function. Compounds bearing an electron-withdrawing group were more easily reduced than those having an electron-donating group and an opposite trend was observed for the oxidation. Ease of oxidation was also computationally rationalized using DFT approach showing increased ease of oxidation with electron donating functionalities. Since electrochemical properties of nitrones are known to correlate with biological properties, this work provides insights in the design of potent nitrone antioxidants. Using cyclic voltammetry the relative rate of superoxide trapping by nitrones was investigated and compared to the classical antioxidant BHT. The determination of the relative rate of phenyl radical trapping was also carried out but showed no clear correlation with the nature of the substituents. This indicates the absence of a polar effect in agreement with previous data and further supports the intermediate nature, that is, non- or weakly nucleophile, of phenyl radical. On the contrary kinetics of hydroxymethyl radical trapping was found to correlate with the nature of the substituents, demonstrating the nucleophilic nature of its addition onto nitrones.

  18. Additional Nucleophile-Free FeCl3-Catalyzed Green Deprotection of 2,4-Dimethoxyphenylmethyl-Protected Alcohols and Carboxylic Acids.

    Science.gov (United States)

    Sawama, Yoshinari; Masuda, Masahiro; Honda, Akie; Yokoyama, Hiroki; Park, Kwihwan; Yasukawa, Naoki; Monguchi, Yasunari; Sajiki, Hironao

    2016-01-01

    The deprotection of the methoxyphenylmethyl (MPM) ether and ester derivatives can be generally achieved by the combinatorial use of a catalytic Lewis acid and stoichiometric nucleophile. The deprotections of 2,4-dimethoxyphenylmethyl (DMPM)-protected alcohols and carboxylic acids were found to be effectively catalyzed by iron(III) chloride without any additional nucleophile to form the deprotected mother alcohols and carboxylic acids in excellent yields. Since the present deprotection proceeds via the self-assembling mechanism of the 2,4-DMPM protective group itself to give the hardly-soluble resorcinarene derivative as a precipitate, the rigorous purification process by silica-gel column chromatography was unnecessary and the sufficiently-pure alcohols and carboxylic acids were easily obtained in satisfactory yields after simple filtration.

  19. Glassy carbon electrode modified with horse radish peroxidase/organic nucleophilic-functionalized carbon nanotube composite for enhanced electrocatalytic oxidation and efficient voltammetric sensing of levodopa

    Energy Technology Data Exchange (ETDEWEB)

    Shoja, Yalda; Rafati, Amir Abbas, E-mail: aa_rafati@basu.ac.ir; Ghodsi, Javad

    2016-01-01

    A novel and selective enzymatic biosensor was designed and constructed for voltammetric determination of levodopa (L-Dopa) in aqueous media (phosphate buffer solution, pH = 7). Biosensor development was on the basis of to physically immobilizing of horse radish peroxidase (HRP) as electrochemical catalyst by sol–gel on glassy carbon electrode modified with organic nucleophilic carbon nanotube composite which in this composite p-phenylenediamine (pPDA) as organic nucleophile chemically bonded with functionalized MWCNT (MWCNT-COOH). The results of this study suggest that prepared bioorganic nucleophilic carbon nanotube composite (HRP/MWCNT-pPDA) shows fast electron transfer rate for electro oxidation of L-Dopa because of its high electrochemical catalytic activity toward the oxidation of L-Dopa, more −NH{sub 2} reactive sites and large effective surface area. Also in this work we measured L-Dopa in the presence of folic acid and uric acid as interferences. The proposed biosensor was characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), FT-IR spectroscopy and cyclic voltammetry (CV). The differential pulse voltammetry (DPV) was used for determination of L-Dopa from 0.1 μM to 1.9 μM with a low detection limit of 40 nM (for S/N = 3) and sensitivity was about 35.5 μA/μM. Also this biosensor has several advantages such as rapid response, high stability and reproducibility. - Highlights: • Glassy carbon electrode modified by a novel composite in which pPDA as nucleophile is chemically attached to MWCNTs. • The developed biosensor exhibited excellent electrocatalytic activity in electrochemically determination of L-Dopa. • The biosensor showed acceptable sensitivity, reproducibility, detection limit, selectivity and stability. • MWCNT-pPDA provides a good electrical conductivity and large effective surface area for enzyme immobilization.

  20. Approaches in Substitution of Organic Solvents

    DEFF Research Database (Denmark)

    Jacobsen, Thomas

    2000-01-01

    In substitution of harmful chemicals or products with less harmful or harmless ones, there are different approaches according to the different situations, the technical requirements to the substitutes, and the goals for the substitution. Three different cases are presented. The substitution process...

  1. 4-alkyl-L-(Dehydro)proline biosynthesis in actinobacteria involves N-terminal nucleophile-hydrolase activity of γ-glutamyltranspeptidase homolog for C-C bond cleavage

    Science.gov (United States)

    Zhong, Guannan; Zhao, Qunfei; Zhang, Qinglin; Liu, Wen

    2017-07-01

    γ-Glutamyltranspeptidases (γ-GTs), ubiquitous in glutathione metabolism for γ-glutamyl transfer/hydrolysis, are N-terminal nucleophile (Ntn)-hydrolase fold proteins that share an autoproteolytic process for self-activation. γ-GT homologues are widely present in Gram-positive actinobacteria where their Ntn-hydrolase activities, however, are not involved in glutathione metabolism. Herein, we demonstrate that the formation of 4-Alkyl-L-(dehydro)proline (ALDP) residues, the non-proteinogenic α-amino acids that serve as vital components of many bioactive metabolites found in actinobacteria, involves unprecedented Ntn-hydrolase activity of γ-GT homologue for C-C bond cleavage. The related enzymes share a key Thr residue, which acts as an internal nucleophile for protein hydrolysis and then as a newly released N-terminal nucleophile for carboxylate side-chain processing likely through the generation of an oxalyl-Thr enzyme intermediate. These findings provide mechanistic insights into the biosynthesis of various ALDP residues/associated natural products, highlight the versatile functions of Ntn-hydrolase fold proteins, and particularly generate interest in thus far less-appreciated γ-GT homologues in actinobacteria.

  2. LOW TEMPERATURE FORMATION OF NITROGEN-SUBSTITUTED POLYCYCLIC AROMATIC HYDROCARBONS (PANHs)—BARRIERLESS ROUTES TO DIHYDRO(iso)QUINOLINES

    Energy Technology Data Exchange (ETDEWEB)

    Parker, Dorian S. N.; Yang, Tao; Dangi, Beni B.; Kaiser, Ralf I. [Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Bera, Partha P.; Lee, Timothy J., E-mail: ralfk@hawaii.edu, E-mail: Timothy.J.Lee@nasa.gov [Space Science and Astrobiology Division, NASA Ames Research Center, Moffett Field, Mountain View, CA 94035 (United States)

    2015-12-20

    Meteorites contain bio-relevant molecules such as vitamins and nucleobases, which consist of aromatic structures with embedded nitrogen atoms. Questions remain over the chemical mechanisms responsible for the formation of nitrogen-substituted polycyclic aromatic hydrocarbons (PANHs) in extraterrestrial environments. By exploiting single collision conditions, we show that a radical mediated bimolecular collision between pyridyl radicals and 1,3-butadiene in the gas phase forms nitrogen-substituted polycyclic aromatic hydrocarbons (PANHs) 1,4-dihydroquinoline and to a minor amount 1,4-dihydroisoquinoline. The reaction proceeds through the formation of a van der Waals complex, which circumnavigates the entrance barrier implying it can operate at very low kinetic energy and therefore at low temperatures of 10 K as present in cold molecular clouds such as TMC-1. The discovery of facile de facto barrierless exoergic reaction mechanisms leading to PANH formation could play an important role in providing a population of aromatic structures upon which further photo-processing of ice condensates could occur to form nucleobases.

  3. C-Terminally modified peptides via cleavage of the HMBA linker by O-, N- or S-nucleophiles

    DEFF Research Database (Denmark)

    Hansen, Jonas; Diness, Frederik; Meldal, Morten Peter

    2016-01-01

    A large variety of C-terminally modified peptides was obtained by nucleophilic cleavage of the ester bond in solid phase linked peptide esters of 4-hydroxymethyl benzamide (HMBA). The developed methods provided peptides, C-terminally functionalized as esters, amides and thioesters, with high purity...... directly from the resin in a single reaction step. A comprehensive screening of the reaction conditions and scope for nucleophilic cleavage of peptides from the HMBA linker was performed....

  4. 40 CFR 721.2577 - Copper complex of (substituted sulfonaphthyl azo substituted phenyl) disulfonaphthyl azo, amine...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Copper complex of (substituted... Copper complex of (substituted sulfonaphthyl azo substituted phenyl) disulfonaphthyl azo, amine salt... substances identified generically as copper complex of (substituted sulfonaphthyl azo substituted phenyl...

  5. Substituted decision making: elder guardianship.

    Science.gov (United States)

    Leatherman, Martha E; Goethe, Katherine E

    2009-11-01

    The goal of this column is to help experienced clinicians navigate the judicial system when they are confronted with requests for capacity evaluations that involve guardianship (conservatorship). The interface between the growing elderly medical population and increasing requests for substituted decision making is becoming more complex. This column will help practicing psychiatrists understand the medical, legal, and societal factors involved in adult guardianship. Such understanding is necessary in order to effectively perform guardianship evaluations and adequately inform courts, patients, and families about the psychiatric diagnoses central to substituted decision making.

  6. Effect of Microwave Irradiation on the Condensation of 6-Substituted 3-Formylchromones with Some Five-membered Heterocyclic Compounds

    Directory of Open Access Journals (Sweden)

    Nada Pronayova

    2000-02-01

    Full Text Available Different types of 3-substituted 4H-4-oxobenzopyrans were prepared by microwave irradiation as well as by a classical method. The beneficial effect of microwave irradiation on the aldol condensation of 3-formylchromones with 2-imino-1-methylimidazolidine-4-one (creatinine, 2-thioxoimidazolidine-4-one (thiohydantoin and 2-ethyl-2-thioxothiazolidin-4-one (3-ethylrhodanine in different reaction media is described. Our results show that the effect of microwave irradiation on the reactions studied was a shortening of the reaction times and a smooth increase in the yields. The subsequent reactions of the product with some nucleophiles are discussed. The structure of the products was proven by elemental analysis, IR and NMR spectra.

  7. Substitution determination of Fmoc‐substituted resins at different wavelengths

    Science.gov (United States)

    Kley, Markus; Bächle, Dirk; Loidl, Günther; Meier, Thomas; Samson, Daniel

    2017-01-01

    In solid‐phase peptide synthesis, the nominal batch size is calculated using the starting resin substitution and the mass of the starting resin. The starting resin substitution constitutes the basis for the calculation of a whole set of important process parameters, such as the number of amino acid derivative equivalents. For Fmoc‐substituted resins, substitution determination is often performed by suspending the Fmoc‐protected starting resin in 20% (v/v) piperidine in DMF to generate the dibenzofulvene–piperidine adduct that is quantified by ultraviolet–visible spectroscopy. The spectrometric measurement is performed at the maximum absorption wavelength of the dibenzofulvene–piperidine adduct, that is, at 301.0 nm. The recorded absorption value, the resin weight and the volume are entered into an equation derived from Lambert–Beer's law, together with the substance‐specific molar absorption coefficient at 301.0 nm, in order to calculate the nominal substitution. To our knowledge, molar absorption coefficients between 7100 l mol−1 cm−1 and 8100 l mol−1 cm−1 have been reported for the dibenzofulvene–piperidine adduct at 301.0 nm. Depending on the applied value, the nominal batch size may differ up to 14%. In this publication, a determination of the molar absorption coefficients at 301.0 and 289.8 nm is reported. Furthermore, proof is given that by measuring the absorption at 289.8 nm the impact of wavelength accuracy is reduced. © 2017 The Authors Journal of Peptide Science published by European Peptide Society and John Wiley & Sons Ltd. PMID:28635051

  8. Substitution determination of Fmoc-substituted resins at different wavelengths.

    Science.gov (United States)

    Eissler, Stefan; Kley, Markus; Bächle, Dirk; Loidl, Günther; Meier, Thomas; Samson, Daniel

    2017-10-01

    In solid-phase peptide synthesis, the nominal batch size is calculated using the starting resin substitution and the mass of the starting resin. The starting resin substitution constitutes the basis for the calculation of a whole set of important process parameters, such as the number of amino acid derivative equivalents. For Fmoc-substituted resins, substitution determination is often performed by suspending the Fmoc-protected starting resin in 20% (v/v) piperidine in DMF to generate the dibenzofulvene-piperidine adduct that is quantified by ultraviolet-visible spectroscopy. The spectrometric measurement is performed at the maximum absorption wavelength of the dibenzofulvene-piperidine adduct, that is, at 301.0 nm. The recorded absorption value, the resin weight and the volume are entered into an equation derived from Lambert-Beer's law, together with the substance-specific molar absorption coefficient at 301.0 nm, in order to calculate the nominal substitution. To our knowledge, molar absorption coefficients between 7100 l mol -1  cm -1 and 8100 l mol -1  cm -1 have been reported for the dibenzofulvene-piperidine adduct at 301.0 nm. Depending on the applied value, the nominal batch size may differ up to 14%. In this publication, a determination of the molar absorption coefficients at 301.0 and 289.8 nm is reported. Furthermore, proof is given that by measuring the absorption at 289.8 nm the impact of wavelength accuracy is reduced. © 2017 The Authors Journal of Peptide Science published by European Peptide Society and John Wiley & Sons Ltd. © 2017 The Authors Journal of Peptide Science published by European Peptide Society and John Wiley & Sons Ltd.

  9. Title: Elucidation of Environmental Fate of Artificial Sweeteners (Aspartame, Acesulfame K and Saccharin) by Determining Bimolecular Rate Constants with Hydroxyl Radical at Various pH and Temperature Conditions and Possible Reaction By-Products

    Science.gov (United States)

    Teraji, T.; Arakaki, T.; Suzuka, T.

    2012-12-01

    Use of artificial sweeteners in beverages and food has been rapidly increasing because of their non-calorie nature. In Japan, aspartame, acesulfame K and sucralose are among the most widely used artificial sweeteners. Because the artificial sweeteners are not metabolized in human bodies, they are directly excreted into the environment without chemical transformations. We initiated a study to better understand the fate of artificial sweeteners in the marine environment. The hydroxyl radical (OH), the most potent reactive oxygen species, reacts with various compounds and determines the environmental oxidation capacity and the life-time of many compounds. The steady-state OH concentration and the reaction rate constants between the compound and OH are used to estimate the life-time of the compound. In this study, we determine the bimolecular rate constants between aspartame, acefulfame K and saccharin and OH at various pH and temperature conditions using a competition kinetics technique. We use hydrogen peroxide as a photochemical source of OH. Bimolecular rate constant we obtained so far for aspartame was (2.6±1.2)×109 M-1 s-1 at pH = 3.0 and (4.9±2.3)×109 M-1 s-1 at pH = 5.5. Little effect was seen by changing the temperatures between 15 and 40 oC. Activation energy (Ea) was calculated to be -1.0 kJ mol-1 at pH = 3.0, +8.5 kJ mol-1 at pH = 5.5, which could be regarded as zero. We will report bimolecular rate constants at different pHs and temperatures for acesulfame K and saccharin, as well. Possible reaction by-products for aspartame will be also reported. We will further discuss the fate of aspartame in the coastal environment.

  10. Detection of Heteromers Formed by Cannabinoid CB1, Dopamine D2, and Adenosine A2A G-Protein-Coupled Receptors by Combining Bimolecular Fluorescence Complementation and Bioluminescence Energy Transfer

    Science.gov (United States)

    Navarro, Gemma; Carriba, Paulina; Gandí, Jorge; Ciruela, Francisco; Casadó, Vicent; Cortés, Antoni; Mallol, Josefa; Canela, Enric I.; Lluis, Carmen; Franco, Rafael

    2008-01-01

    Functional interactions in signaling occur between dopamine D2 (D2R) and cannabinoid CB1 (CB1R) receptors, between CB1R and adenosine A2A (A2AR) receptors, and between D2R and A2AR. Furthermore, direct molecular interactions have been reported for the pairs CB1R-D2R, A2AR-D2R, and CB1R-A2AR. Here a combination of bimolecular fluorescence complementation and bioluminescence energy transfer techniques was used to identify the occurrence of D2R-CB1R-A2AR hetero-oligomers in living cells. PMID:18956124

  11. Detection of Heteromers Formed by Cannabinoid CB1, Dopamine D2, and Adenosine A2A G-Protein-Coupled Receptors by Combining Bimolecular Fluorescence Complementation and Bioluminescence Energy Transfer

    Directory of Open Access Journals (Sweden)

    Gemma Navarro

    2008-01-01

    Full Text Available Functional interactions in signaling occur between dopamine D2 (D2R and cannabinoid CB1 (CB1R receptors, between CB1R and adenosine A2A (A2AR receptors, and between D2R and A2AR. Furthermore, direct molecular interactions have been reported for the pairs CB1R-D2R, A2AR-D2R, and CB1R-A2AR. Here a combination of bimolecular fluorescence complementation and bioluminescence energy transfer techniques was used to identify the occurrence of D2R-CB1R-A2AR hetero-oligomers in living cells.

  12. Polymer Main-Chain Substitution Effects on the Efficiency of Nonfullerene BHJ Solar Cells

    KAUST Repository

    Firdaus, Yuliar; Maffei, Luna Pratali; Cruciani, Federico; Mü ller, Michael A.; Liu, Shengjian; Lopatin, Sergei; Wehbe, Nimer; Ngongang Ndjawa, Guy Olivier; Amassian, Aram; Laquai, Fré dé ric; Beaujuge, Pierre

    2017-01-01

    “Nonfullerene” acceptors are proving effective in bulk heterojunction (BHJ) solar cells when paired with selected polymer donors. However, the principles that guide the selection of adequate polymer donors for high-efficiency BHJ solar cells with nonfullerene acceptors remain a matter of some debate and, while polymer main-chain substitutions may have a direct influence on the donor–acceptor interplay, those effects should be examined and correlated with BHJ device performance patterns. This report examines a set of wide-bandgap polymer donor analogues composed of benzo[1,2-b:4,5-b′]dithiophene (BDT), and thienyl ([2H]T) or 3,4-difluorothiophene ([2F]T) motifs, and their BHJ device performance pattern with the nonfullerene acceptor “ITIC”. Studies show that the fluorine- and ring-substituted derivative PBDT(T)[2F]T largely outperforms its other two polymer donor counterparts, reaching power conversion efficiencies as high as 9.8%. Combining several characterization techniques, the gradual device performance improvements observed on swapping PBDT[2H]T for PBDT[2F]T, and then for PBDT(T)[2F]T, are found to result from (i) notably improved charge generation and collection efficiencies (estimated as ≈60%, 80%, and 90%, respectively), and (ii) reduced geminate recombination (being suppressed from ≈30%, 25% to 10%) and bimolecular recombination (inferred from recombination rate constant comparisons). These examinations will have broader implications for further studies on the optimization of BHJ solar cell efficiencies with polymer donors and a wider range of nonfullerene acceptors.

  13. Polymer Main-Chain Substitution Effects on the Efficiency of Nonfullerene BHJ Solar Cells

    KAUST Repository

    Firdaus, Yuliar

    2017-07-21

    “Nonfullerene” acceptors are proving effective in bulk heterojunction (BHJ) solar cells when paired with selected polymer donors. However, the principles that guide the selection of adequate polymer donors for high-efficiency BHJ solar cells with nonfullerene acceptors remain a matter of some debate and, while polymer main-chain substitutions may have a direct influence on the donor–acceptor interplay, those effects should be examined and correlated with BHJ device performance patterns. This report examines a set of wide-bandgap polymer donor analogues composed of benzo[1,2-b:4,5-b′]dithiophene (BDT), and thienyl ([2H]T) or 3,4-difluorothiophene ([2F]T) motifs, and their BHJ device performance pattern with the nonfullerene acceptor “ITIC”. Studies show that the fluorine- and ring-substituted derivative PBDT(T)[2F]T largely outperforms its other two polymer donor counterparts, reaching power conversion efficiencies as high as 9.8%. Combining several characterization techniques, the gradual device performance improvements observed on swapping PBDT[2H]T for PBDT[2F]T, and then for PBDT(T)[2F]T, are found to result from (i) notably improved charge generation and collection efficiencies (estimated as ≈60%, 80%, and 90%, respectively), and (ii) reduced geminate recombination (being suppressed from ≈30%, 25% to 10%) and bimolecular recombination (inferred from recombination rate constant comparisons). These examinations will have broader implications for further studies on the optimization of BHJ solar cell efficiencies with polymer donors and a wider range of nonfullerene acceptors.

  14. Bimolecular reaction of CH3 + CO in solid p-H2: Infrared absorption of acetyl radical (CH3CO) and CH3-CO complex

    Science.gov (United States)

    Das, Prasanta; Lee, Yuan-Pern

    2014-06-01

    We have recorded infrared spectra of acetyl radical (CH3CO) and CH3-CO complex in solid para-hydrogen (p-H2). Upon irradiation at 248 nm of CH3C(O)Cl/p-H2 matrices, CH3CO was identified as the major product; characteristic intense IR absorption features at 2990.3 (ν9), 2989.1 (ν1), 2915.6 (ν2), 1880.5 (ν3), 1419.9 (ν10), 1323.2 (ν5), 836.6 (ν7), and 468.1 (ν8) cm-1 were observed. When CD3C(O)Cl was used, lines of CD3CO at 2246.2 (ν9), 2244.0 (ν1), 1866.1 (ν3), 1046.7 (ν5), 1029.7 (ν4), 1027.5 (ν10), 889.1 (ν6), and 723.8 (ν7) cm-1 appeared. Previous studies characterized only three vibrational modes of CH3CO and one mode of CD3CO in solid Ar. In contrast, upon photolysis of a CH3I/CO/p-H2 matrix with light at 248 nm and subsequent annealing at 5.1 K before re-cooling to 3.2 K, the CH3-CO complex was observed with characteristic IR features at 3165.7, 3164.5, 2150.1, 1397.6, 1396.4, and 613.0 cm-1. The assignments are based on photolytic behavior, observed deuterium isotopic shifts, and a comparison of observed vibrational wavenumbers and relative IR intensities with those predicted with quantum-chemical calculations. This work clearly indicates that CH3CO can be readily produced from photolysis of CH3C(O)Cl because of the diminished cage effect in solid p-H2 but not from the reaction of CH3 + CO because of the reaction barrier. Even though CH3 has nascent kinetic energy greater than 87 kJ mol-1 and internal energy ˜42 kJ mol-1 upon photodissociation of CH3I at 248 nm, its energy was rapidly quenched so that it was unable to overcome the barrier height of ˜27 kJ mol-1 for the formation of CH3CO from the CH3 + CO reaction; a barrierless channel for formation of a CH3-CO complex was observed instead. This rapid quenching poses a limitation in production of free radicals via bimolecular reactions in p-H2.

  15. Behavioral service substitution (Chapter 9)

    NARCIS (Netherlands)

    Stahl, C.; Aalst, van der W.M.P.; Bouguettaya, A.; Sheng, Q.Z.; Daniel, F.

    2014-01-01

    Service-oriented design supports system evolution and encourages reuse and modularization. A key ingredient of service orientation is the ability to substitute one service by another without reconfiguring the overall system. This chapter aims to give an overview of the state of the art and open

  16. prismane structure by silicon substitution

    Indian Academy of Sciences (India)

    Using the second-order Møller–Plesset perturbation (MP2) theoretic method and the cc-pVDZ basis set, it is shown that with an increase in the number of carbon atoms substituted by silicon, the [6]-prismane structure becomes increasingly more stable, relative to the two isolated benzene (like) structures. A similar trend is ...

  17. Story of skeletally substituted benzenes

    Indian Academy of Sciences (India)

    Unknown

    values are extensively used to define aromaticity quantitatively.3 In a recent study on ... studies were directed to unravel the subtle ways in which the stability, reactivity, and ..... The singlet–triplet gaps of all the skeletally substituted benzenes ...

  18. 40 CFR Appendix D to Subpart G of... - Substitutes Subject to Use Restrictions and Unacceptable Substitutes

    Science.gov (United States)

    2010-07-01

    ... the following criteria, derived from Society of Automotive Engineers (SAE) standards and recommended... Substitutes] Application Substitute Decision Conditions Comments Electronics Cleaning w/CFC-113 and MCF HFC... Sector [Acceptable Subject to Narrowed Use Limits] Application Substitute Decision Comments Electronics...

  19. Homoaromatics as intermediates in the substitution reactions of 1,2,4,5-tetrazines with ammonia and hydrazine

    International Nuclear Information System (INIS)

    Counotte-Potman, A.D.

    1981-01-01

    This thesis describes some nucleophilic substitution reactions between the red 1,2,4,5-tetrazines and hydrazine-hydrate or ammonia. Special attention was paid to the occurrence of the Ssub(N) (ANRORC) mechanism in these substitution reactions. This mechanism comprises a sequence of reactions, involving the Addition of a Nucleopile to a heteroaromatic species, followed by a Ring-Opening and Ring Closure reaction to the substitution product. 3-Alkyl(aryl)-1,2,4,5-tetrazines were found to undergo a Chichibabin hydrazination into 6-hydrazino-3-alkyl(aryl)-1,2,4,5-tetrazines on treatment with hydrazine-hydrate. The first step in this reaction sequence was the formation of a homoaromatic sigma-adduct. Subsequently an open-chain intermediate was observed by NMR, on raising the temperature. Finally the hydrazino compound is formed by ring closure. This reaction sequence can be considered as an Ssub(N)(ANRORC) process. With 15 N-labelled hydrazine, only part of the label was found to be built in the 1,2,4,5-tetrazine ring of the 6-hydrazino compounds. This is the first example of a reaction in which both the hydrazino compound with the 15 N-label in the ring and with the 15 N-label in the exocyclic hydrazino group are formed according to the Ssub(N)(ANRORC) mechanism. (Auth.)

  20. Uranium nucleophilic carbene complexes

    International Nuclear Information System (INIS)

    Tourneux, Jean-Christophe

    2012-01-01

    The only stable f-metal carbene complexes (excluding NHC) metals f present R 2 C 2- groups having one or two phosphorus atoms in the central carbon in alpha position. The objective of this work was to develop the chemistry of carbenes for uranium (metal 5f) with the di-anion C{Ph 2 P(=S)} 2 2- (SCS 2- ) to extend the organometallic chemistry of this element in its various oxidation states (+3-+6), and to reveal the influence of the 5f orbitals on the nature and reactivity of the double bond C=U. We first isolated the reactants M(SCHS) (M = Li and K) and demonstrated the role of the cation M + on the evolution of the di-anion M 2 SCS (M = Li, K, Tl) which is transformed into LiSCHS in THF or into product of intramolecular cyclization K 2 [C(PhPS) 2 (C 6 H 4 )]. We have developed the necessary conditions mono-, bis- and tris-carbene directly from the di-anion SCS 2- and UCl 4 , as the precursor used in uranium chemistry. The protonolysis reactions of amides compounds (U-NEt 2 ) by the neutral ligand SCH 2 S were also studied. The compounds [Li(THF)] 2 [U(SCS)Cl 3 ] and [U(SCS)Cl 2 (THF) 2 ] were then used to prepare a variety of cyclopentadienyl and mono-cyclo-octa-tetra-enyliques uranium(IV) carbene compounds of the DFT analysis of compounds [M(SCS)Cl 2 (py) 2 ] and [M(Cp) 2 (SCS)] (M = U, Zr) reveals the strong polarization of the M=C double bond, provides information on the nature of the σ and π interactions in this binding, and shows the important role of f orbitals. The influence of ancillary ligands on the M=C bond is revealed by examining the effects of replacing Cl - ligands and pyridine by C 5 H 5 - groups. Mulliken and NBO analyzes show that U=C bond, unlike the Zr=C bond, is not affected by the change in environment of the metal center. While the oxidation tests of carbene complexes of U(IV) were disappointing, the first carbene complex of uranium (VI), [UO 2 (SCS)(THF) 2 ], was isolated with the uranyl ion UO 2 2+ . The reactions of compounds UO 2 X 2 (X = I, OTf) with anions SCS 2- and SCHS - provide the first notable developments in the organometallic chemistry of the uranyl ion. DFT studies show the essentially ionic binding U(VI)-R and U(VI)=C and the small contribution of 5f orbitals covalently. (author) [fr

  1. Smart Phones and their Substitutes

    DEFF Research Database (Denmark)

    Bødker, Mads; Gimpel, Gregory; Hedman, Jonas

    2009-01-01

    Drawing on data from a longitudinal field study, this paper investigates the influence of existing, better and stand-alone technology substitutes on the use of smart phones. By applying prospect theory, media richness theory, and business model literature, the purpose of this paper is to improve...... our understanding of the role of substitutes, device content fit issues, and implications for business models by asking the question: What is an effective business model to address the relationship between user preference and the fit of the smart phone and everyday task? The field study data suggest...... the need for business models to recognize that adoption decisions are reference-dependent and strongly influenced by the fit between task and smart phone....

  2. Bone healing and bone substitutes.

    Science.gov (United States)

    Costantino, Peter D; Hiltzik, David; Govindaraj, Satish; Moche, Jason

    2002-02-01

    With the advent of new biomaterials and surgical techniques, the reconstructive surgeon has a wider range of treatment modalities for the rehabilitation and reconstruction of craniofacial skeletal deformities than ever before. These innovative substances act as true bone graft substitutes, thereby allowing the surgeon to avoid the use of autogenous bone grafts and their associated donor site morbidity. Surgeons have long been interested in producing a composite graft that can heal faster by induction, incorporate with surrounding tissues, and be remodeled to resemble native bone. Currently, there are a host of bone graft substitutes available that vary in both their composition and properties. Craniomaxillofacial surgeons must therefore become comfortable with numerous biomaterials to best tailor the treatment for each patient individually. Ongoing investigations into the next phase of tissue engineering will continue to bring us closer to the ability to regenerate or replace bone.

  3. Substituting oil by electric power

    International Nuclear Information System (INIS)

    Lichtenberg, H.

    1981-01-01

    Parting from the development of primary energy use the author refers to the latest investigations and results presented on the 1980 World Energy Conference and with special regard to oil points out the threatening exhaustion of fossil energy resources. Maintaining the economic structure of the Federal Republic of Germany implies an orientation away from oil. Due to its flexible application technology and quasi-inexhaustible energy resources electric power may substantially contribute to oil substitution which as a matter of fact is of particular interest in connection with the heat market. Coal alone cannot substitute both oil and nuclear energy. Thus, the above postulates the use of the latter. Leaving nuclear energy inactive today will effect an increase in the demand for oil the negative consequences of which would weight heavily upon the anyhow unbalanced import/export ratio of the Federal Republic of Germany. (orig.) [de

  4. 40 CFR 721.4420 - Substituted hydroxylamine.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Substituted hydroxylamine. 721.4420... Substances § 721.4420 Substituted hydroxylamine. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as substituted hydroxylamine (PMN P-84-492) is...

  5. Substituted Indoleacetic Acids Tested in Tissue Cultures

    DEFF Research Database (Denmark)

    Engvild, Kjeld Christensen

    1978-01-01

    Monochloro substituted IAA inhibited shoot induction in tobacco tissue cultures about as much as IAA. Dichloro substituted IAA inhibited shoot formation less. Other substituted IAA except 5-fluoro- and 5-bromoindole-3-acetic acid were less active than IAA. Callus growth was quite variable...

  6. Substitutes for School Nurses in Illinois

    Science.gov (United States)

    Vollinger, Linda Jeno; Bergren, Martha Dewey; Belmonte-Mann, Frances

    2011-01-01

    The purpose of this descriptive study was to explore utilization of nurse substitutes in the school setting in Illinois. The literature described personnel who staff the school health office in the absence of the school nurse and the barriers to obtaining nurse substitutes. There were no empirical studies conducted on school nurse substitutes in…

  7. Dynamics of the NbCl5-catalyzed cycloaddition of propylene oxide and CO2: Assessing the dual role of the nucleophilic co-catalysts

    KAUST Repository

    D'Elia, Valerio

    2014-07-23

    A mechanistic study on the synthesis of propylene carbonate (PC) from CO2 and propylene oxide (PO) catalyzed by NbCl5 and organic nucleophiles such as 4-dimethylaminopyridine (DMAP) or tetra-n-butylammonium bromide (NBu4Br) is reported. A combination of in situ spectroscopic techniques and kinetic studies has been used to provide detailed insight into the reaction mechanism, the formation of intermediates, and interactions between the reaction partners. The results of DFT calculations support the experimental observations and allow us to propose a mechanism for this reaction. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Onium ions. XVI. Hydrogen--deuterium exchange accompanying the cleavage of ammonium (tetradeuterioammonium) trifluoroacetate by lithium deuteride (hydride) indicating Sn2 like nucleophilic displacement at quaternary nitrogen through pentacoordinated NH5

    International Nuclear Information System (INIS)

    Olah, G.A.; Donovan, D.J.; Shen, J.; Klopman, G.

    1975-01-01

    The reactions of ammonium trifluoroacetate and lithium hydride, of ammonium trifluoroacetate and lithium deuteride, and of tetradeuteroammonium trifluoroacetate and lithium hydride were studied in an attempt to prove experimentally nucleophilic displacement through the formation of pentacoordinated NH 5 . Significant isotopic scramblings were observed in the reaction products. An analysis of possible side reactions indicated that the most reasonable explanation for the reaction products obtained is the attack of D - on the quarternary hydrogen of NH 4 + in an SN2-like fashion causing exchange to occur via pentacoordinated NH 4 D. The possibility of a real pentacoordinated intermediate was also considered. CNDO/2 calculations show that a nucleophilic attack on hydrogen is favored, but the alternative attack on nitrogen can not be dismissed because of the experimental data. The reaction of NF 4 + SbF 6 - and LiF could indicate the possibility of nucleophilic attack on nitrogen. (U.S.)

  9. Biologic and synthetic skin substitutes: An overview.

    Science.gov (United States)

    Halim, Ahmad Sukari; Khoo, Teng Lye; Mohd Yussof, Shah Jumaat

    2010-09-01

    The current trend of burn wound care has shifted to more holistic approach of improvement in the long-term form and function of the healed burn wounds and quality of life. This has demanded the emergence of various skin substitutes in the management of acute burn injury as well as post burn reconstructions. Skin substitutes have important roles in the treatment of deep dermal and full thickness wounds of various aetiologies. At present, there is no ideal substitute in the market. Skin substitutes can be divided into two main classes, namely, biological and synthetic substitutes. The biological skin substitutes have a more intact extracellular matrix structure, while the synthetic skin substitutes can be synthesised on demand and can be modulated for specific purposes. Each class has its advantages and disadvantages. The biological skin substitutes may allow the construction of a more natural new dermis and allow excellent re-epithelialisation characteristics due to the presence of a basement membrane. Synthetic skin substitutes demonstrate the advantages of increase control over scaffold composition. The ultimate goal is to achieve an ideal skin substitute that provides an effective and scar-free wound healing.

  10. Biologic and synthetic skin substitutes: An overview

    Directory of Open Access Journals (Sweden)

    Halim Ahmad

    2010-10-01

    Full Text Available The current trend of burn wound care has shifted to more holistic approach of improvement in the long-term form and function of the healed burn wounds and quality of life. This has demanded the emergence of various skin substitutes in the management of acute burn injury as well as post burn reconstructions. Skin substitutes have important roles in the treatment of deep dermal and full thickness wounds of various aetiologies. At present, there is no ideal substitute in the market. Skin substitutes can be divided into two main classes, namely, biological and synthetic substitutes. The biological skin substitutes have a more intact extracellular matrix structure, while the synthetic skin substitutes can be synthesised on demand and can be modulated for specific purposes. Each class has its advantages and disadvantages. The biological skin substitutes may allow the construction of a more natural new dermis and allow excellent re-epithelialisation characteristics due to the presence of a basement membrane. Synthetic skin substitutes demonstrate the advantages of increase control over scaffold composition. The ultimate goal is to achieve an ideal skin substitute that provides an effective and scar-free wound healing.

  11. Novel non-symmetrical bifunctionally-substituted phthalonitriles and corresponding d-metal phthalocyaninates

    Science.gov (United States)

    Vashurin, Artur; Maizlish, Vladimir; Tikhomirova, Tatiyana; Nemtseva, Marina; Znoyko, Serafima; Aleksandriiskii, Viktor

    2018-05-01

    The work reports synthesis of 4-(2-tert-butyl-4,5-dicyanophenylsulfonyl)benzene and its analogue containing carboxyl group in phenyl fragment by nucleophilic substitution of nitro-group of 4-tert-butyl-5-nitrophthalonitrile. Unique structure of the obtained compounds is explained by presence of bulky tert-butyl substituent in combination with carboxyl group, which being part of phthalocyanine molecule impart it higher solubility within different solvents (organic and water mediums) and act as anchoring groups. Based on obtained nitriles phthalocyanine complexes of copper, nickel, cobalt and magnesium are synthesized with good yields. Demetallization of initial magnesium phthalocyanine by hydrochloric acid was performed in order to obtain ligand of phthalocyanine. Synthetic and purification techniques are described in detail. Obtained substances are of specific structure making them to be applied in sensorics for smart materials production, as sensitizers or part of molecular magnets. The structure, NMR and IR spectra are modeled using special software. Resulting experimental and theoretical data are compared. The results show sufficient correlation that confirms correctness of chosen methods and its applicability for theoretical studying compounds related to investigated ones.

  12. Computational study of cation substitutions in apatites

    International Nuclear Information System (INIS)

    Tamm, Toomas; Peld, Merike

    2006-01-01

    Density-functional theory plane-wave modeling of fluor- and hydroxyapatites has been performed, where one or two calcium ions per unit cell were replaced with cadmium or zinc cations. It was found that cadmium ions favor Ca(1) positions in fluorapatites and Ca(2) positions in hydroxyapatites, in agreement with experiment. A similar pattern is predicted for zinc substitutions. In the doubly substituted cases, where only hydroxyapatites were modeled, a preference for the substituting ions to be located in Ca(2) position was also observed. Displacement of the hydroxide ions from their symmetrical positions on the hexagonal axis can be used to explain the preferred configurations of substituting ions around the axis. -- Deformation of the hydroxide ion chain due to substitutions around the ion channel in substituted hydroxyapatites

  13. The Morishima Gross elasticity of substitution

    OpenAIRE

    Blackorby, Charles; Primont, Daniel; Russell, R. Robert

    2007-01-01

    We show that the Hotelling-Lau elasticity of substitution, an extension of the Allen-Uzawa elasticity to allow for optimal output-quantity (or utility) responses to changes in factor prices, inherits all of the failings of the Allen-Uzawa elasticity identified by Blackorby and Russell [1989 AER]. An analogous extension of the Morishima elasticity of substitution to allow for output quantity changes preserves the salient properties of the original Hicksian notion of elasticity of substitution.

  14. Statistical Physics of Complex Substitutive Systems

    Science.gov (United States)

    Jin, Qing

    Diffusion processes are central to human interactions. Despite extensive studies that span multiple disciplines, our knowledge is limited to spreading processes in non-substitutive systems. Yet, a considerable number of ideas, products, and behaviors spread by substitution; to adopt a new one, agents must give up an existing one. This captures the spread of scientific constructs--forcing scientists to choose, for example, a deterministic or probabilistic worldview, as well as the adoption of durable items, such as mobile phones, cars, or homes. In this dissertation, I develop a statistical physics framework to describe, quantify, and understand substitutive systems. By empirically exploring three collected high-resolution datasets pertaining to such systems, I build a mechanistic model describing substitutions, which not only analytically predicts the universal macroscopic phenomenon discovered in the collected datasets, but also accurately captures the trajectories of individual items in a complex substitutive system, demonstrating a high degree of regularity and universality in substitutive systems. I also discuss the origins and insights of the parameters in the substitution model and possible generalization form of the mathematical framework. The systematical study of substitutive systems presented in this dissertation could potentially guide the understanding and prediction of all spreading phenomena driven by substitutions, from electric cars to scientific paradigms, and from renewable energy to new healthy habits.

  15. Substitution dynamical systems spectral analysis

    CERN Document Server

    Queffélec, Martine

    2010-01-01

    This volume mainly deals with the dynamics of finitely valued sequences, and more specifically, of sequences generated by substitutions and automata. Those sequences demonstrate fairly simple combinatorical and arithmetical properties and naturally appear in various domains. As the title suggests, the aim of the initial version of this book was the spectral study of the associated dynamical systems: the first chapters consisted in a detailed introduction to the mathematical notions involved, and the description of the spectral invariants followed in the closing chapters. This approach, combined with new material added to the new edition, results in a nearly self-contained book on the subject. New tools - which have also proven helpful in other contexts - had to be developed for this study. Moreover, its findings can be concretely applied, the method providing an algorithm to exhibit the spectral measures and the spectral multiplicity, as is demonstrated in several examples. Beyond this advanced analysis, many...

  16. Controversial issues of maternity substitution

    Directory of Open Access Journals (Sweden)

    Andy Pușcă

    2009-06-01

    Full Text Available Substitute maternity consists in a woman carrying a pregnancy (the implant of an embryo, at therequest of a sterile couple, most of the times in exchange of a sum of money, with her commitment tounconditionally give away the newborn after birth to the couple she concluded the agreement with. Manycontroversies emerged in what concerns the contract between the sterile couple and the carrying mother,especially when this contract is by onerous title, which happens in most of the cases. In that a civil contract? Is ita sales contract for the child? Is it a contract to provide services? Is it body marketing? Between total prohibitionand excessive liberalism, the middle way, which is the regulation according to ethical religious, cultural andsocial norms of each community, represents a realistic solution.

  17. Photoelectron Spectroscopy of Substituted Phenylnitrenes

    Science.gov (United States)

    Wijeratne, Neloni R.; Da Fonte, Maria; Wenthold, Paul G.

    2009-06-01

    Nitrenes are unusual molecular structures with unfilled electronic valences that are isoelectronic with carbenes. Although, both can be generated by either thermal or photochemical decomposition of appropriate precursors they usually exhibit different reactivities. In this work, we carry out spectroscopic studies of substituted phenylnitrene to determine how the introduction of substituents will affect the reactivity and its thermochemical properties. All studies were carried out by using the newly constructed time-of-flight negative ion photoelectron spectrometer (NIPES) at Purdue University. The 355 nm photoelectron spectra of the o-, m-, and p-chlorophenyl nitrene anions are fairly similar to that measured for phenylnitrene anion. All spectra show low energy triplet state and a high energy singlet state. The singlet state for the meta isomer is well-resolved, with a well defined origin and observable vibrational structure. Whereas the singlet states for the ortho and para isomers have lower energy onsets and no resolved structure. The isomeric dependence suggests that the geometry differences result from the resonance interaction between the nitrogen and the substituent. Quinoidal resonance structures are possible for the open-shell singlet states of the o- and p-chlorinated phenyl nitrenes. The advantages of this type of electronic structures for the open-shell singlet states is that the unpaired electrons can be more localized on separate atoms in the molecules, minimizing the repulsion between. Because the meta position is not in resonance with the nitrenes, substitution at that position should not affect the structure of the open-shell singlet state. The measured electron affinities (EA) of the triplet phenylnitrenes are in excellent agreement with the values predicted by electronic structure calculations. The largest EA, 1.82 eV is found for the meta isomer, with para being the smallest, 1.70 eV.

  18. 2-Bromo-1,4-naphthoquinone: a potentially improved substitute of menadione in Apatone™ therapy

    Directory of Open Access Journals (Sweden)

    F.S. Graciani

    2012-08-01

    Full Text Available Apatone™, a combination of menadione (2-methyl-1,4-naphthoquinone, VK3 and ascorbic acid (vitamin C, VC is a new strategy for cancer treatment. Part of its effect on tumor cells is related to the cellular pro-oxidative imbalance provoked by the generation of hydrogen peroxide (H2O2 through naphthoquinone redox cycling. In this study, we attempted to find new naphthoquinone derivatives that would increase the efficiency of H2O2 production, thereby potentially increasing its efficacy for cancer treatment. The presence of an electron-withdrawing group in the naphthoquinone moiety had a direct effect on the efficiency of H2O2 production. The compound 2-bromo-1,4-naphthoquinone (BrQ, in which the bromine atom substituted the methyl group in VK3, was approximately 10- and 19-fold more efficient than VK3 in terms of oxygen consumption and H2O2 production, respectively. The ratio [H2O2]produced / [naphthoquinone]consumed was 68 ± 11 and 5.8 ± 0.2 (µM/µM for BrQ and VK3, respectively, indicating a higher efficacy of BrQ as a catalyst for the autoxidation of ascorbic acid. Both VK3 and BrQ reacted with glutathione (GSH, but BrQ was the more effective substrate. Part of GSH was incorporated into the naphthoquinone, producing a nucleophilic substitution product (Q-SG. The depletion of BrQ by GSH did not prevent its redox capacity since Q-SG was also able to catalyze the production of reactive oxygen species. VK3/VC has already been submitted to clinical trials for the treatment of prostate cancer and has demonstrated promising results. However, replacement of VK3 with BrQ will open new lines of investigation regarding this approach to cancer treatment.

  19. 2-Bromo-1,4-naphthoquinone: a potentially improved substitute of menadione in Apatone™ therapy

    International Nuclear Information System (INIS)

    Graciani, F.S.; Ximenes, V.F.

    2012-01-01

    Apatone™, a combination of menadione (2-methyl-1,4-naphthoquinone, VK 3 ) and ascorbic acid (vitamin C, VC) is a new strategy for cancer treatment. Part of its effect on tumor cells is related to the cellular pro-oxidative imbalance provoked by the generation of hydrogen peroxide (H 2 O 2 ) through naphthoquinone redox cycling. In this study, we attempted to find new naphthoquinone derivatives that would increase the efficiency of H 2 O 2 production, thereby potentially increasing its efficacy for cancer treatment. The presence of an electron-withdrawing group in the naphthoquinone moiety had a direct effect on the efficiency of H 2 O 2 production. The compound 2-bromo-1,4-naphthoquinone (BrQ), in which the bromine atom substituted the methyl group in VK 3 , was approximately 10- and 19-fold more efficient than VK 3 in terms of oxygen consumption and H 2 O 2 production, respectively. The ratio [H 2 O 2 ] produced / [naphthoquinone] consumed was 68 ± 11 and 5.8 ± 0.2 (µM/µM) for BrQ and VK 3 , respectively, indicating a higher efficacy of BrQ as a catalyst for the autoxidation of ascorbic acid. Both VK 3 and BrQ reacted with glutathione (GSH), but BrQ was the more effective substrate. Part of GSH was incorporated into the naphthoquinone, producing a nucleophilic substitution product (Q-SG). The depletion of BrQ by GSH did not prevent its redox capacity since Q-SG was also able to catalyze the production of reactive oxygen species. VK 3 /VC has already been submitted to clinical trials for the treatment of prostate cancer and has demonstrated promising results. However, replacement of VK 3 with BrQ will open new lines of investigation regarding this approach to cancer treatment

  20. Theoretical study of the nucleophilic addition of oximes to the nitrile complexes trans-/cis-[ReCl4(NCCH3)2

    International Nuclear Information System (INIS)

    Klestova-Nadeeva, E. A.; Kuznetsov, M. L.; Dement'ev, A. I.

    2005-01-01

    The reaction of nucleophilic addition of oximes (HON=CRR 1 ) to organic nitriles coordinated in the rhenium complexes trans-/cis-[ReCl 4 (NCCH 3 ) 2 ] was theoretically studied by the Hartree-Fock and density functional theory (B3LYP) methods. The reaction mechanism involves (I) the initial change of the oxime conformation; (II) the formation of the orientation complex with the coordinated nitrile molecule, which transforms into a four-membered transition state; (III) the formation of the addition product in a less stable conformation; and (IV) the formation of the ultimate addition product. The calculations make it possible to interpret the activation of nitriles in terms of the activated complex theory as a result of stabilization of the transition state in going from the free to the coordinated nitrile [ru

  1. Preparation of 7-substituted ginkgolide derivatives

    DEFF Research Database (Denmark)

    Vogensen, Stine Byskov; Strømgaard, Kristian; Shindou, Hideo

    2003-01-01

    alpha-fluoro ginkgolide B was equipotent to ginkgolide B underlining the critical importance of the 7-position of ginkgolides for PAF receptor activity. Herein we describe the synthesis of a series of ginkgolide B derivatives with modifications at the 7-position and the pharmacological evaluation...... of these derivatives as assayed by cloned PAF receptors. In two cases nucleophilic attack on a 7beta-O-triflate ginkgolide B did not lead to the expected products, but gave rise to two unprecedented ginkgolide derivatives, one with a novel rearranged skeleton. Furthermore, standard reduction of 7alpha-azido ginkgolide......-chloro ginkgolide B, the most potent nonaromatic ginkgolide derivative described to date with a K(i) value of 110 nM....

  2. Sulfur Denitrosylation by an Engineered Trx-like DsbG Enzyme Identifies Nucleophilic Cysteine Hydrogen Bonds as Key Functional Determinant.

    Science.gov (United States)

    Lafaye, Céline; Van Molle, Inge; Tamu Dufe, Veronica; Wahni, Khadija; Boudier, Ariane; Leroy, Pierre; Collet, Jean-François; Messens, Joris

    2016-07-15

    Exposure of bacteria to NO results in the nitrosylation of cysteine thiols in proteins and low molecular weight thiols such as GSH. The cells possess enzymatic systems that catalyze the denitrosylation of these modified sulfurs. An important player in these systems is thioredoxin (Trx), a ubiquitous, cytoplasmic oxidoreductase that can denitrosylate proteins in vivo and S-nitrosoglutathione (GSNO) in vitro However, a periplasmic or extracellular denitrosylase has not been identified, raising the question of how extracytoplasmic proteins are repaired after nitrosative damage. In this study, we tested whether DsbG and DsbC, two Trx family proteins that function in reducing pathways in the Escherichia coli periplasm, also possess denitrosylating activity. Both DsbG and DsbC are poorly reactive toward GSNO. Moreover, DsbG is unable to denitrosylate its specific substrate protein, YbiS. Remarkably, by borrowing the CGPC active site of E. coli Trx-1 in combination with a T200M point mutation, we transformed DsbG into an enzyme highly reactive toward GSNO and YbiS. The pKa of the nucleophilic cysteine, as well as the redox and thermodynamic properties of the engineered DsbG are dramatically changed and become similar to those of E. coli Trx-1. X-ray structural insights suggest that this results from a loss of two direct hydrogen bonds to the nucleophilic cysteine sulfur in the DsbG mutant. Our results highlight the plasticity of the Trx structural fold and reveal that the subtle change of the number of hydrogen bonds in the active site of Trx-like proteins is the key factor that thermodynamically controls reactivity toward nitrosylated compounds. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. Type Substitution for Object-Oriented Programming

    DEFF Research Database (Denmark)

    Schwartzbach, Michael Ignatieff; Palsberg, Jens

    1990-01-01

    Genericity allows the substitution of types in a class. This is usually obtained through parameterized classes, although they are inflexible since any class can be inherited but is not in itself parameterized. We suggest a new genericity mechanism, type substitution, which is a subclassing concep...

  4. Multisensory integration, sensory substitution and visual rehabilitation

    DEFF Research Database (Denmark)

    Proulx, Michael J; Ptito, Maurice; Amedi, Amir

    2014-01-01

    Sensory substitution has advanced remarkably over the past 35 years since first introduced to the scientific literature by Paul Bach-y-Rita. In this issue dedicated to his memory, we describe a collection of reviews that assess the current state of neuroscience research on sensory substitution...

  5. Educators Take Another Look at Substitutes

    Science.gov (United States)

    Zubrzycki, Jaclyn

    2012-01-01

    The mythology surrounding the substitute teacher is not a pretty one: Paper airplanes, lost learning, bullying. But as schools collect more information about teacher absenteeism and its consequences, districts and schools are exploring ways to professionalize substitute teaching--or experiment with alternative ways of coping with teacher absences.…

  6. Substitution between cars within the household

    DEFF Research Database (Denmark)

    De Borger, Bruno; Mulalic, Ismir; Rouwendal, Jan

    2016-01-01

    In this paper we study the demand for car kilometres in two-car households, focusing on the substitution between cars of different fuel efficiency in response to fuel price changes. We use a large sample of detailed Danish data on two-car households to estimate – for each car owned by the household...... – own and cross-price effects of increases in fuel costs per kilometre. The empirical results show that failure to capture substitution between cars within the household can result in substantial misspecification biases. Ignoring substitution, the basic model yielded fuel price elasticities of 0.......98 and 1.41 for the primary and secondary cars, respectively. Accounting for substitution effects, these figures reduce to, respectively, 0.32 and 0.45. Consistent with substitution behaviour, we find that the fuel price elasticity of fuel demand exceeds the elasticity of kilometre demands with respect...

  7. Elasticity of Substitution and Antidumping Measures

    DEFF Research Database (Denmark)

    Drud Hansen, Jørgen; Meinen, Philipp; Nielsen, Jørgen Ulff-Møller

    Abstract This paper analyzes the role of the elasticity of substitution for anti-dumping decisions across countries. In monopolistic competition models with cost heterogeneous firms across countries, price differences vary inversely with the elasticity of substitution. Anti-dumping duties should...... therefore also vary inversely with the elasticity of substitution at least for countries which have a strong focus on prices in the determination of their anti-dumping measures. We test this for ten countries from 1990 to 2009 using data on anti-dumping from Chad Bown (2010) and US-data at 8-digit level...... in our empirical investigation support the predicted role of the elasticity of substitution as we find a significant negative relation between the elasticity of substitution and the final anti-dumping duties for the ‘lesser duty rule’ group of countries. The countries which do not follow the ‘lesser duty...

  8. Substituted Hydroxyapatites with Antibacterial Properties

    Directory of Open Access Journals (Sweden)

    Joanna Kolmas

    2014-01-01

    Full Text Available Reconstructive surgery is presently struggling with the problem of infections located within implantation biomaterials. Of course, the best antibacterial protection is antibiotic therapy. However, oral antibiotic therapy is sometimes ineffective, while administering an antibiotic at the location of infection is often associated with an unfavourable ratio of dosage efficiency and toxic effect. Thus, the present study aims to find a new factor which may improve antibacterial activity while also presenting low toxicity to the human cells. Such factors are usually implemented along with the implant itself and may be an integral part of it. Many recent studies have focused on inorganic factors, such as metal nanoparticles, salts, and metal oxides. The advantages of inorganic factors include the ease with which they can be combined with ceramic and polymeric biomaterials. The following review focuses on hydroxyapatites substituted with ions with antibacterial properties. It considers materials that have already been applied in regenerative medicine (e.g., hydroxyapatites with silver ions and those that are only at the preliminary stage of research and which could potentially be used in implantology or dentistry. We present methods for the synthesis of modified apatites and the antibacterial mechanisms of various ions as well as their antibacterial efficiency.

  9. Substituted Hydroxyapatites with Antibacterial Properties

    Science.gov (United States)

    Kolmas, Joanna; Groszyk, Ewa; Kwiatkowska-Różycka, Dagmara

    2014-01-01

    Reconstructive surgery is presently struggling with the problem of infections located within implantation biomaterials. Of course, the best antibacterial protection is antibiotic therapy. However, oral antibiotic therapy is sometimes ineffective, while administering an antibiotic at the location of infection is often associated with an unfavourable ratio of dosage efficiency and toxic effect. Thus, the present study aims to find a new factor which may improve antibacterial activity while also presenting low toxicity to the human cells. Such factors are usually implemented along with the implant itself and may be an integral part of it. Many recent studies have focused on inorganic factors, such as metal nanoparticles, salts, and metal oxides. The advantages of inorganic factors include the ease with which they can be combined with ceramic and polymeric biomaterials. The following review focuses on hydroxyapatites substituted with ions with antibacterial properties. It considers materials that have already been applied in regenerative medicine (e.g., hydroxyapatites with silver ions) and those that are only at the preliminary stage of research and which could potentially be used in implantology or dentistry. We present methods for the synthesis of modified apatites and the antibacterial mechanisms of various ions as well as their antibacterial efficiency. PMID:24949423

  10. Modeling competitive substitution in a polyelectrolyte complex

    International Nuclear Information System (INIS)

    Peng, B.; Muthukumar, M.

    2015-01-01

    We have simulated the invasion of a polyelectrolyte complex made of a polycation chain and a polyanion chain, by another longer polyanion chain, using the coarse-grained united atom model for the chains and the Langevin dynamics methodology. Our simulations reveal many intricate details of the substitution reaction in terms of conformational changes of the chains and competition between the invading chain and the chain being displaced for the common complementary chain. We show that the invading chain is required to be sufficiently longer than the chain being displaced for effecting the substitution. Yet, having the invading chain to be longer than a certain threshold value does not reduce the substitution time much further. While most of the simulations were carried out in salt-free conditions, we show that presence of salt facilitates the substitution reaction and reduces the substitution time. Analysis of our data shows that the dominant driving force for the substitution process involving polyelectrolytes lies in the release of counterions during the substitution

  11. Determinants of generic drug substitution in Switzerland

    Directory of Open Access Journals (Sweden)

    Lufkin Thomas M

    2011-01-01

    Full Text Available Abstract Background Since generic drugs have the same therapeutic effect as the original formulation but at generally lower costs, their use should be more heavily promoted. However, a considerable number of barriers to their wider use have been observed in many countries. The present study examines the influence of patients, physicians and certain characteristics of the generics' market on generic substitution in Switzerland. Methods We used reimbursement claims' data submitted to a large health insurer by insured individuals living in one of Switzerland's three linguistic regions during 2003. All dispensed drugs studied here were substitutable. The outcome (use of a generic or not was modelled by logistic regression, adjusted for patients' characteristics (gender, age, treatment complexity, substitution groups and with several variables describing reimbursement incentives (deductible, co-payments and the generics' market (prices, packaging, co-branded original, number of available generics, etc.. Results The overall generics' substitution rate for 173,212 dispensed prescriptions was 31%, though this varied considerably across cantons. Poor health status (older patients, complex treatments was associated with lower generic use. Higher rates were associated with higher out-of-pocket costs, greater price differences between the original and the generic, and with the number of generics on the market, while reformulation and repackaging were associated with lower rates. The substitution rate was 13% lower among hospital physicians. The adoption of the prescribing practices of the canton with the highest substitution rate would increase substitution in other cantons to as much as 26%. Conclusions Patient health status explained a part of the reluctance to substitute an original formulation by a generic. Economic incentives were efficient, but with a moderate global effect. The huge interregional differences indicated that prescribing behaviours and

  12. Sensory Substitution and Multimodal Mental Imagery.

    Science.gov (United States)

    Nanay, Bence

    2017-09-01

    Many philosophers use findings about sensory substitution devices in the grand debate about how we should individuate the senses. The big question is this: Is "vision" assisted by (tactile) sensory substitution really vision? Or is it tactile perception? Or some sui generis novel form of perception? My claim is that sensory substitution assisted "vision" is neither vision nor tactile perception, because it is not perception at all. It is mental imagery: visual mental imagery triggered by tactile sensory stimulation. But it is a special form of mental imagery that is triggered by corresponding sensory stimulation in a different sense modality, which I call "multimodal mental imagery."

  13. Biologic and synthetic skin substitutes: An overview

    OpenAIRE

    Halim, Ahmad Sukari; Khoo, Teng Lye; Mohd. Yussof, Shah Jumaat

    2010-01-01

    The current trend of burn wound care has shifted to more holistic approach of improvement in the long-term form and function of the healed burn wounds and quality of life. This has demanded the emergence of various skin substitutes in the management of acute burn injury as well as post burn reconstructions. Skin substitutes have important roles in the treatment of deep dermal and full thickness wounds of various aetiologies. At present, there is no ideal substitute in the market. Skin substit...

  14. Computational Study of Chemical Reactivity Using Information-Theoretic Quantities from Density Functional Reactivity Theory for Electrophilic Aromatic Substitution Reactions.

    Science.gov (United States)

    Wu, Wenjie; Wu, Zemin; Rong, Chunying; Lu, Tian; Huang, Ying; Liu, Shubin

    2015-07-23

    The electrophilic aromatic substitution for nitration, halogenation, sulfonation, and acylation is a vastly important category of chemical transformation. Its reactivity and regioselectivity is predominantly determined by nucleophilicity of carbon atoms on the aromatic ring, which in return is immensely influenced by the group that is attached to the aromatic ring a priori. In this work, taking advantage of recent developments in quantifying nucleophilicity (electrophilicity) with descriptors from the information-theoretic approach in density functional reactivity theory, we examine the reactivity properties of this reaction system from three perspectives. These include scaling patterns of information-theoretic quantities such as Shannon entropy, Fisher information, Ghosh-Berkowitz-Parr entropy and information gain at both molecular and atomic levels, quantitative predictions of the barrier height with both Hirshfeld charge and information gain, and energetic decomposition analyses of the barrier height for the reactions. To that end, we focused in this work on the identity reaction of the monosubstituted-benzene molecule reacting with hydrogen fluoride using boron trifluoride as the catalyst in the gas phase. We also considered 19 substituting groups, 9 of which are ortho/para directing and the other 9 meta directing, besides the case of R = -H. Similar scaling patterns for these information-theoretic quantities found for stable species elsewhere were disclosed for these reactions systems. We also unveiled novel scaling patterns for information gain at the atomic level. The barrier height of the reactions can reliably be predicted by using both the Hirshfeld charge and information gain at the regioselective carbon atom. The energy decomposition analysis ensued yields an unambiguous picture about the origin of the barrier height, where we showed that it is the electrostatic interaction that plays the dominant role, while the roles played by exchange-correlation and

  15. The radiochemistry of [{sup 18} F]-FDG: the first experience in Mexico; La radioquimica del [{sup 18} F]-FDG: la primera experiencia en Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Lopez D, F A [Unidad PET-Ciclotron, Facultad de Medicina, UNAM, Av. Universidad 3000, Ciudad Universitaria, Coyoacan, 04500 Mexico, D. F. (Mexico)

    2004-07-01

    The present work describes the more used method for the synthesis of 2 - [{sup 18} F] - fluorine-2-deoxy-D-glucose that is the more used radiopharmaceutical in the nuclear medicine in the cancer diagnostic. The process consists on two chemical reactions: i) [{sup 18} F{sup -}] - nucleophilic radio fluorination and i i) a hydrolysis catalyzed by acid. The first reaction incorporates to the [{sup 18} F]- fluorine labelled inside the organic precursor 1,3,4,6-tetra- O -acetil-2- O-trifluoromethanesulfonyl- {beta}-D-mannopyranose (triflate of mannose). The mechanism of this reaction is a bimolecular nucleophilic substitution (SN{sub 2}) with the ion [{sup 18} F{sup -}] - fluoride; in the second reaction, the hydrolysis of those protective acetyl groups generate the hydroxyl groups free of the [{sup 18} F]-FDG. The process includes an azeotropic distillation and several purification steps. (Author)

  16. The radiochemistry of [18 F]-FDG: the first experience in Mexico

    International Nuclear Information System (INIS)

    Lopez D, F.A.

    2004-01-01

    The present work describes the more used method for the synthesis of 2 - [ 18 F] - fluorine-2-deoxy-D-glucose that is the more used radiopharmaceutical in the nuclear medicine in the cancer diagnostic. The process consists on two chemical reactions: i) [ 18 F - ] - nucleophilic radio fluorination and i i) a hydrolysis catalyzed by acid. The first reaction incorporates to the [ 18 F]- fluorine labelled inside the organic precursor 1,3,4,6-tetra- O -acetil-2- O-trifluoromethanesulfonyl- β-D-mannopyranose (triflate of mannose). The mechanism of this reaction is a bimolecular nucleophilic substitution (SN 2 ) with the ion [ 18 F - ] - fluoride; in the second reaction, the hydrolysis of those protective acetyl groups generate the hydroxyl groups free of the [ 18 F]-FDG. The process includes an azeotropic distillation and several purification steps. (Author)

  17. Substitution within the Danish printing industry

    DEFF Research Database (Denmark)

    Larsen, Henrik Fred; Bøg, Carsten

    2009-01-01

    are running a substitution project. A major part of the work has been mapping the presence of chemicals which are potential candidates for substitution (e.g. PBT, CMR, vPvB, EDS) within the Danish printing industry and this work was recently finished. The mapping comprises a combination of a literature study......The implementation of the EU REACH regulation will most probably promote substitution within sectors handling a lot of different chemicals like the printing industry. With the aim of being at the cutting edge of this development the Danish EPA together with the Danish printing industry and IPU...... total 15 substances) were found in the Danish printing industry. This paper presents the results of the mapping of chemical candidates and the first results on preparing for actual substitutions....

  18. Substituted hydroxyapatites for biomedical applications: A review

    Czech Academy of Sciences Publication Activity Database

    Šupová, Monika

    2015-01-01

    Roč. 41, č. 8 (2015), s. 9203-9231 ISSN 0272-8842 Institutional support: RVO:67985891 Keywords : bioapatite * calcium phosphate * hydroxyapatite * substitution Subject RIV: JJ - Other Materials Impact factor: 2.758, year: 2015

  19. Dodecatungstocobaltate and Sn (IV)-Substituted Polyoxometalate ...

    African Journals Online (AJOL)

    NICO

    work metals, or substituting different cations for the protons to make their acidic or neutral ... corrosive materials in comparison with traditional Lewis acids. The importance of .... salt by treatment with potassium chloride. Finally, the cobalt (II).

  20. Questioning nuclear waste substitution: a case study.

    Science.gov (United States)

    Marshall, Alan

    2007-03-01

    This article looks at the ethical quandaries, and their social and political context, which emerge as a result of international nuclear waste substitution. In particular it addresses the dilemmas inherent within the proposed return of nuclear waste owned by Japanese nuclear companies and currently stored in the United Kingdom. The UK company responsible for this waste, British Nuclear Fuels Limited (BNFL), wish to substitute this high volume intermediate-level Japanese-owned radioactive waste for a much lower volume of much more highly radioactive waste. Special focus is given to ethical problems that they, and the UK government, have not wished to address as they move forward with waste substitution. The conclusion is that waste substitution can only be considered an ethical practice if a set of moderating conditions are observed by all parties. These conditions are listed and, as of yet, they are not being observed.

  1. DOES CURRENCY SUBSTITUTION AFFECT EXCHANGE RATE VOLATILITY?

    Directory of Open Access Journals (Sweden)

    Hisao Kumamoto

    2014-10-01

    Full Text Available This study investigates the impacts of the degree of currency substitution on nominal exchange rate volatility in seven countries (Indonesia, the Philippines, the Czech Republic, Hungary, Poland, Argentina, and Peru. We use the Threshold ARCH model to consider the ratchet effect of currency substitution and sample periods in the 2000s, during which time the economies of the sample countries stabilized, while the U.S. dollar and euro depreciated against other major currencies following the recent global financial crisis. The presented empirical analyses show that the degree of currency substitution has significant positive effects on the conditional variance of the depreciation rate of the nominal exchange rate in most sample countries. Moreover, a shock to the depreciation rate of the nominal exchange rate has asymmetric effects on the conditional variance, depending on the sign. One possible explanation for these differential effects is the existence of the ratchet effect of currency substitution.

  2. Development of a diesel substitute fuel

    Energy Technology Data Exchange (ETDEWEB)

    Reiter, Anton; Mair-Zelenka, Philipp [Graz Univ. of Technology (Austria). Inst. of Chemical Engineering and Environmental Technology; Zeymer, Marc [OMV Refining and Marketing GmbH, Vienna (Austria). MRDI-D Product Development and Innovation

    2013-06-01

    Substitute fuels composed of few real chemical compounds are an alternative characterisation approach for conventional fuels as opposed to the traditional pseudo-component method. With the algorithm proposed in this paper the generation of such substitutes will be facilitated and well-established thermodynamic methods can be applied for physical property-data prediction. Based on some quality criteria like true boiling-point curve, liquid density, C/H ratio, or cloud point of a target fuel a surrogate which meets these properties is determined by fitting its composition. The application and capabilities of the algorithm developed are demonstrated by means of an exemplary diesel substitute fuel. The substitute mixture obtained can be generated and used for evaluation of property-prediction methods. Furthermore this approach can help to understand the effects of mixing fossil fuels with biogenic compounds. (orig.)

  3. Hyperfine magnetic fields in substituted Finemet alloys

    Energy Technology Data Exchange (ETDEWEB)

    Brzózka, K., E-mail: k.brzozka@uthrad.pl [University of Technology and Humanities in Radom, Department of Physics (Poland); Sovák, P. [P.J. Šafárik University, Institute of Physics (Slovakia); Szumiata, T.; Gawroński, M.; Górka, B. [University of Technology and Humanities in Radom, Department of Physics (Poland)

    2016-12-15

    Transmission Mössbauer spectroscopy was used to determine the hyperfine fields of Finemet-type alloys in form of ribbons, substituted alternatively by Mn, Ni, Co, Al, Zn, V or Ge of various concentration. The comparative analysis of magnetic hyperfine fields was carried out which enabled to understand the role of added elements in as-quenched as well as annealed samples. Moreover, the influence of the substitution on the mean direction of the local hyperfine magnetic field was examined.

  4. Trace maps of general substitutional sequences

    International Nuclear Information System (INIS)

    Kolar, M.; Nori, F.

    1990-01-01

    It is shown that for arbitrary n, there exists a trace map for any n-letter substitutional sequence. Trace maps are explicitly obtained for the well-known circle and Rudin-Shapiro sequences which can be defined by means of substitution rules on three and four letters, respectively. The properties of the two trace maps and their consequences for various spectral properties are briefly discussed

  5. Product portfolio optimization based on substitution

    DEFF Research Database (Denmark)

    Myrodia, Anna; Moseley, A.; Hvam, Lars

    2017-01-01

    The development of production capabilities has led to proliferation of the product variety offered to the customer. Yet this fact does not directly imply increase of manufacturers' profitability, nor customers' satisfaction. Consequently, recent research focuses on portfolio optimization through...... substitution and standardization techniques. However when re-defining the strategic market decisions are characterized by uncertainty due to several parameters. In this study, by using a GAMS optimization model we present a method for supporting strategic decisions on substitution, by quantifying the impact...

  6. Currency Substitution and Inflation in Peru

    OpenAIRE

    Liliana Rojas-Suárez

    1992-01-01

    This paper shows that there is a long-run relationship between the expected rate of depreciation in the black-market-exchange rate and the ratio of domestic to foreign money in Peru; that is, the hypothesis of currency substitution can explain the behavior of real holdings of money in Peru. The paper also shows that, while the importance of currency substitution as a transmission mechanism through which domestic policies affected the dynamics of inflation was relatively small during a period ...

  7. Substituting missing data in compositional analysis

    Energy Technology Data Exchange (ETDEWEB)

    Real, Carlos, E-mail: carlos.real@usc.es [Area de Ecologia, Departamento de Biologia Celular y Ecologia, Escuela Politecnica Superior, Universidad de Santiago de Compostela, 27002 Lugo (Spain); Angel Fernandez, J.; Aboal, Jesus R.; Carballeira, Alejo [Area de Ecologia, Departamento de Biologia Celular y Ecologia, Facultad de Biologia, Universidad de Santiago de Compostela, 15782 Santiago de Compostela (Spain)

    2011-10-15

    Multivariate analysis of environmental data sets requires the absence of missing values or their substitution by small values. However, if the data is transformed logarithmically prior to the analysis, this solution cannot be applied because the logarithm of a small value might become an outlier. Several methods for substituting the missing values can be found in the literature although none of them guarantees that no distortion of the structure of the data set is produced. We propose a method for the assessment of these distortions which can be used for deciding whether to retain or not the samples or variables containing missing values and for the investigation of the performance of different substitution techniques. The method analyzes the structure of the distances among samples using Mantel tests. We present an application of the method to PCDD/F data measured in samples of terrestrial moss as part of a biomonitoring study. - Highlights: > Missing values in multivariate data sets must be substituted prior to analysis. > The substituted values can modify the structure of the data set. > We developed a method to estimate the magnitude of the alterations. > The method is simple and based on the Mantel test. > The method allowed the identification of problematic variables in a sample data set. - A method is presented for the assessment of the possible distortions in multivariate analysis caused by the substitution of missing values.

  8. Substituting missing data in compositional analysis

    International Nuclear Information System (INIS)

    Real, Carlos; Angel Fernandez, J.; Aboal, Jesus R.; Carballeira, Alejo

    2011-01-01

    Multivariate analysis of environmental data sets requires the absence of missing values or their substitution by small values. However, if the data is transformed logarithmically prior to the analysis, this solution cannot be applied because the logarithm of a small value might become an outlier. Several methods for substituting the missing values can be found in the literature although none of them guarantees that no distortion of the structure of the data set is produced. We propose a method for the assessment of these distortions which can be used for deciding whether to retain or not the samples or variables containing missing values and for the investigation of the performance of different substitution techniques. The method analyzes the structure of the distances among samples using Mantel tests. We present an application of the method to PCDD/F data measured in samples of terrestrial moss as part of a biomonitoring study. - Highlights: → Missing values in multivariate data sets must be substituted prior to analysis. → The substituted values can modify the structure of the data set. → We developed a method to estimate the magnitude of the alterations. → The method is simple and based on the Mantel test. → The method allowed the identification of problematic variables in a sample data set. - A method is presented for the assessment of the possible distortions in multivariate analysis caused by the substitution of missing values.

  9. [Guidelines for substitution treatments in prison populations].

    Science.gov (United States)

    Michel, L; Maguet, O

    2005-01-01

    Care access for the drug addict patients in prison (in particular for the treatments of substitution) in France is very unequal from one establishment to another. This reflects the great variability of the practices of substitution and especially the absence of consensus on the methods of adaptation of these practices to the prison environment. Because of difficulties expressed by prisoners and medical staff on this subject and of stakes (let us recall that approximately 30% of the prisoners are dependent or abusers of one or more psychoactive substances), the formulation of recommendations or of a good practices guide of substitution in prison appeared necessary. Work that we detail here answers a ordering of the Advisory Commission of the Treatments of Substitution (September 2001) whose authors are members. It was presented at the session April 2003. It results from the confrontation of a review of the literature (including legal texts and official reports concerning substitution, the organization of the care in prison environment and the lawful framework), with a vast investigation. The latter was carried out near medical staff (22 prisons), penitentiary staff (3 prisons, 27 people met including directors of these establishments) and prisoners (7 establishments, 28 prisoners met) in the form of individual talks (semi-directing interviews with evaluation of the type of existing device and its knowledge by the penitentiary staff and the prisoners; statement of the suggestions, needs and requests of the medical, penitentiary staffs and of the prisoners). In the whole visited prisons, 7.8% (870) of the prisoners received substitution treatments (6.35% by buprenorphine, 1.44% by methadone), representing a proportion of substituted drug addicts (870 substituted for an evaluation of 3,350 prisoners drug addicts among the 11,168 prisoners of the 22 visited prisons) notably lower than that in free environment (56%, ie 96,000 substituted for an evaluated population of

  10. Protein alkylation, transcriptional responses and cytochrome c release during acrolein toxicity in A549 cells: influence of nucleophilic culture media constituents.

    Science.gov (United States)

    Thompson, Colin A; Burcham, Philip C

    2008-06-01

    Acrolein is a toxic combustion product that elicits apoptotic and/or necrotic cell death depending on the conditions under which exposure occurs. As a strong electrophile, side-reactions with nucleophilic media constituents seem likely to accompany study of its toxicity in vitro, but these reactions are poorly characterized. We have thus examined the effect of media composition on the toxicity of acrolein in A549 cells. Cells were exposed to acrolein in either Dulbecco's buffered saline (DBS) or F12 supplemented with various concentrations of fetal bovine serum. Cell viability was assessed using the MTT assay, while heme oxygenase-1 (HO-1) and cytoplasmic cytochrome c were measured as respective markers of transcriptional response and apoptosis. Protein damage was evaluated using the protein carbonyl assay. Compared to F12 media (with or without serum), maximal cell death as evaluated using the MTT assay, as well as adduction of intracellular proteins, occurred when cells were exposed to acrolein in DBS. In contrast, cytochrome c release was maximal in cells exposed to acrolein in serum-containing F12, conditions which inhibited protein modification and overt cell death. These findings highlight the need for careful attention to experimental conditions when conducting in vitro toxicological studies of reactive substances.

  11. Construction of a 3D model of nattokinase, a novel fibrinolytic enzyme from Bacillus natto. A novel nucleophilic catalytic mechanism for nattokinase.

    Science.gov (United States)

    Zheng, Zhong-liang; Zuo, Zhen-yu; Liu, Zhi-gang; Tsai, Keng-chang; Liu, Ai-fu; Zou, Guo-lin

    2005-01-01

    A three-dimensional structural model of nattokinase (NK) from Bacillus natto was constructed by homology modeling. High-resolution X-ray structures of Subtilisin BPN' (SB), Subtilisin Carlsberg (SC), Subtilisin E (SE) and Subtilisin Savinase (SS), four proteins with sequential, structural and functional homology were used as templates. Initial models of NK were built by MODELLER and analyzed by the PROCHECK programs. The best quality model was chosen for further refinement by constrained molecular dynamics simulations. The overall quality of the refined model was evaluated. The refined model NKC1 was analyzed by different protein analysis programs including PROCHECK for the evaluation of Ramachandran plot quality, PROSA for testing interaction energies and WHATIF for the calculation of packing quality. This structure was found to be satisfactory and also stable at room temperature as demonstrated by a 300ps long unconstrained molecular dynamics (MD) simulation. Further docking analysis promoted the coming of a new nucleophilic catalytic mechanism for NK, which is induced by attacking of hydroxyl rich in catalytic environment and locating of S221.

  12. Tether-directed synthesis of highly substituted oxasilacycles via an intramolecular allylation employing allylsilanes

    Directory of Open Access Journals (Sweden)

    Cox Liam R

    2007-02-01

    Full Text Available Abstract Background Using a silyl tether to unite an aldehyde electrophile and allylsilane nucleophile into a single molecule allows a subsequent Lewis-acid-mediated allylation to proceed in an intramolecular sense and therefore receive all the benefits associated with such processes. However, with the ability to cleave the tether post allylation, a product that is the result of a net intermolecular reaction can be obtained. In the present study, four diastereoisomeric β-silyloxy-α-methyl aldehydes, which contain an allylsilane tethered through the β-carbinol centre, have been prepared, in order to probe how the relative configuration of the two stereogenic centres affects the efficiency and selectivity of the intramolecular allylation. Results Syn-aldehydes, syn-4a and syn-4b, both react poorly, affording all four possible diastereoisomeric oxasilacycle products. In contrast, the anti aldehydes anti-4a and anti-4b react analogously to substrates that lack substitution at the α-site, affording only two of the four possible allylation products. Conclusion The outcome of the reaction with anti-aldehydes is in accord with reaction proceeding through a chair-like transition state (T.S.. In these systems, the sense of 1,3-stereoinduction can be rationalised by the aldehyde electrophile adopting a pseudoaxial orientation, which will minimise dipole-dipole interactions in the T.S. The 1,4-stereoinduction in these substrates is modest and seems to be modulated by the R substituent in the starting material. In the case of the syn-substrates, cyclisation through a chair T.S. is unlikely as this would require the methyl substituent α to the reacting carbonyl group to adopt an unfavourable pseudoaxial position. It is therefore proposed that these substrates react through poorly-defined T.S.s and consequently exhibit essentially no stereoselectivity.

  13. Investigation of the fluorescence quenching of 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) by certain substituted uracils

    Energy Technology Data Exchange (ETDEWEB)

    Anbazhagan, V. [School of Chemistry, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu (India); Renganathan, R. [School of Chemistry, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu (India)], E-mail: rrengas@yahoo.com

    2009-04-15

    The fluorescence quenching of 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) by a series of uracils has been studied in water and acetonitrile solvents using steady-state and time-resolved fluorescence techniques. The steady-state fluorescence quenching technique has been performed in three different pHs (i.e. 4, 8 and 12). The bimolecular quenching rate constant (k{sub q}) increases with increase in pH of uracils. In acidic pH, a pure hydrogen atom abstraction is proposed as the quenching mechanism. This is supported by a pronounced solvent deuterium isotope effect. Electron transfer from the anionic form of uracil to the excited state of DBO is proposed as a mechanism for quenching in basic pH on the basis of highly exergonic thermodynamics obtained from the Rehm-Weller equation. The variation of k{sub q} is explained on the basis of the electronic effect of substitution in uracils as well.

  14. Investigation of the fluorescence quenching of 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) by certain substituted uracils

    International Nuclear Information System (INIS)

    Anbazhagan, V.; Renganathan, R.

    2009-01-01

    The fluorescence quenching of 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) by a series of uracils has been studied in water and acetonitrile solvents using steady-state and time-resolved fluorescence techniques. The steady-state fluorescence quenching technique has been performed in three different pHs (i.e. 4, 8 and 12). The bimolecular quenching rate constant (k q ) increases with increase in pH of uracils. In acidic pH, a pure hydrogen atom abstraction is proposed as the quenching mechanism. This is supported by a pronounced solvent deuterium isotope effect. Electron transfer from the anionic form of uracil to the excited state of DBO is proposed as a mechanism for quenching in basic pH on the basis of highly exergonic thermodynamics obtained from the Rehm-Weller equation. The variation of k q is explained on the basis of the electronic effect of substitution in uracils as well

  15. 40 CFR Appendix B to Subpart G of... - Substitutes Subject to Use Restrictions and Unacceptable Substitutes

    Science.gov (United States)

    2010-07-01

    ... demonstrate it can be used safely in this end-use. CFC-12 Motor Vehicle Air Conditioners (Retrofit and New... Conditions Application Substitute Decision Conditions Comments CFC-12 Automobile Motor Vehicle Air... refrigerant. CFC-12 Automobile Motor Vehicle Air Conditioning (New equipment only) R-152a as a substitute for...

  16. Effects of solvent and structure on the reactivity of 6-substituted nicotinic acids with diazodiphenylmethane in aprotic solvents

    Directory of Open Access Journals (Sweden)

    BRATISLAV Ž. JOVANOVIĆ

    2009-12-01

    Full Text Available The rate constants for the reactions of diazodiphenylmethane (DDM with 6-substituted nicotinic acids in aprotic solvents at 30 °C were determined. The obtained second order rate constants in aprotic solvents, together with literature data for benzoic and nicotinic acids in protic solvents, were used for the calculation of solvent effects, employing the Kamlet-Taft solvatochromic equation (linear solvation energy relationship – LSER in the form: log k = log k0 + s* + a + b. The correlations of the kinetic data were performed by means of multiple linear regression analysis taking appropriate solvent parameters. The sign of the equation coefficients (s, a and b were in agreement with the postulated reaction mechanism, and the mode of the solvent influences on the reaction rate is discussed based on the correlation results. A similar contribution of the non-specific solvent effect and electrophilic solvation was observed for all acids, while the highest contribution of nucleophilic solvation was influenced by their high acidity. Correlation analysis of the rate data with substituent p parameters in an appropriate solvent using the Hammett equation was also performed. The substituent effect on the acid reactivity was higher in aprotic solvents of higher dipolarity/polarizability. The mode of the transmission of the substituent effect is discussed in light of the contribution of solute–solvent interaction on the acid reactivity.

  17. Synthesis of 19-substituted geldanamycins with altered conformations and their binding to heat shock protein Hsp90

    Science.gov (United States)

    Kitson, Russell R. A.; Chang, Chuan-Hsin; Xiong, Rui; Williams, Huw E. L.; Davis, Adrienne L.; Lewis, William; Dehn, Donna L.; Siegel, David; Roe, S. Mark; Prodromou, Chrisostomos; Ross, David; Moody, Christopher J.

    2013-01-01

    The benzoquinone ansamycin geldanamycin and its derivatives are inhibitors of heat shock protein Hsp90, an emerging target for novel therapeutic agents both in cancer and in neurodegeneration. However, toxicity of these compounds to normal cells has been ascribed to reaction with thiol nucleophiles at the quinone 19-position. We reasoned that blocking this position would ameliorate toxicity, and that it might also enforce a favourable conformational switch of the trans-amide group into the cis-form required for protein binding. We report here an efficient synthesis of such 19-substituted compounds and realization of our hypotheses. Protein crystallography established that the new compounds bind to Hsp90 with, as expected, a cis-amide conformation. Studies on Hsp90 inhibition in cells demonstrated the molecular signature of Hsp90 inhibitors: decreases in client proteins with compensatory increases in other heat shock proteins in both human breast cancer and dopaminergic neural cells, demonstrating their potential for use in the therapy of cancer or neurodegenerative diseases. PMID:23511419

  18. Optimal ordering quantities for substitutable deteriorating items under joint replenishment with cost of substitution

    Science.gov (United States)

    Mishra, Vinod Kumar

    2017-09-01

    In this paper we develop an inventory model, to determine the optimal ordering quantities, for a set of two substitutable deteriorating items. In this inventory model the inventory level of both items depleted due to demands and deterioration and when an item is out of stock, its demands are partially fulfilled by the other item and all unsatisfied demand is lost. Each substituted item incurs a cost of substitution and the demands and deterioration is considered to be deterministic and constant. Items are order jointly in each ordering cycle, to take the advantages of joint replenishment. The problem is formulated and a solution procedure is developed to determine the optimal ordering quantities that minimize the total inventory cost. We provide an extensive numerical and sensitivity analysis to illustrate the effect of different parameter on the model. The key observation on the basis of numerical analysis, there is substantial improvement in the optimal total cost of the inventory model with substitution over without substitution.

  19. [Contingency management in opioid substitution treatment].

    Science.gov (United States)

    Specka, M; Böning, A; Scherbaum, N

    2011-07-01

    The majority of opiate-dependent patients in substitution treatment show additional substance-related disorders. Concomitant use of heroin, alcohol, benzodiazepines or cocaine compromises treatment success. Concomitant drug use may be treated by using contingency management (CM) which is based on learning theory. In CM, abstinence from drugs, as verified by drug screenings, is reinforced directly and contingently. Reinforcers used in CM studies with substituted patients were, amongst others, vouchers and take-home privileges. Studies in the USA show a medium average effect of CM on drug consumption rates and abstinence. The effects decrease markedly after the end of the intervention. We discuss whether CM is applicable within the German substitution treatment system and how it can be combined with other interventions such as selective detoxification treatments or cognitive-behavioural programmes. © Georg Thieme Verlag KG Stuttgart · New York.

  20. Biomaterials in search of a meniscus substitute.

    Science.gov (United States)

    Rongen, Jan J; van Tienen, Tony G; van Bochove, Bas; Grijpma, Dirk W; Buma, Pieter

    2014-04-01

    The menisci fulfill key biomechanical functions in the tibiofemoral (knee) joint. Unfortunately meniscal injuries are quite common and most often treated by (partial) meniscectomy. However, some patients experience enduring symptoms, and, more importantly, it leads to an increased risk for symptomatic osteoarthritis. Over the past decades, researchers have put effort in developing a meniscal substitute able to prevent osteoarthritis and treat enduring clinical symptoms. Grossly, two categories of substitutes are observed: First, a resorbable scaffold mimicking biomechanical function which slowly degrades while tissue regeneration and organization is promoted. Second, a non resorbable, permanent implant which mimics the biomechanical function of the native meniscus. Numerous biomaterials with different (material) properties have been used in order to provide such a substitute. Nevertheless, a clinically applicable cartilage protecting material is not yet emerged. In the current review we provide an overview, and discuss, these different materials and extract recommendations regarding material properties for future developmental research. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Substitution between Cars within the Household

    DEFF Research Database (Denmark)

    de Borger, Bruno; Mulalic, Ismir; Rouwendal, Jan

    In this paper we study the demand for car kilometres in two-car households, focusing on the substitution between cars in response to fuel price changes. We use a large sample of detailed Danish data on two-car households to estimate—for each car owned by the household—own and cross-price effects...... of increases in fuel costs per kilometre. The empirical results show that failure to capture substitution between cars within the household can result in substantial misspecification biases. Ignoring substitution, we estimate fuel price elasticities of –0.81 and -0.65 for the primary and secondary cars...... efficient car, finding partial support for the underlying hypothesis. More importantly, the results of this extended model emphasize the importance of behavioural differences related to the position of the most fuel efficient car in the household, suggesting that households’ fuel efficiency choices...

  2. Substitute energy resource policy in Japan

    International Nuclear Information System (INIS)

    Umehara, Katsuhiko

    1980-01-01

    Japan depends 88% of energy resources and 99.8% of petroleum on imports. The solution of energy problems is now made internationally. As the means for Japan, there are the substitution of other resources for petroleum and its promotion. However, this involves the considerable funds for the development and utilization, which must be borne by the people in the form of tax. For governmental financing, a special account must be set up for the particular purpose. In the research and development of new energy resources, new institution is required. The following matters are described: petroleum shortage coming even in 1980s, the international need of substitute energy development, the need for establishing measures for substitute energy resources, acquisition of the funds, special-account governmental financing, and an institute of new energy development. (author)

  3. Substituting telecommunications for travel - Feasible or desirable

    Science.gov (United States)

    Van Vleck, E. M.

    1974-01-01

    This paper reviews recent advances in telecommunications and examines the detailed structure of travel to estimate the feasibility of substituting telecommunications for various travel objectives. The impact of travel is analyzed from a social, economic, energy, and pollution standpoint to assess the desirability of substitution. Perhaps 35-50% of the nation's travel could, in theory, be replaced by very advanced telecommunications (such as a much improved large-screen teleconferencing network), but public resistance would be massive. Much economic dislocation would result since, for example, over 25% of retail sales are travel-related. The energy savings would be modest since only 25% of the nation's energy is consumed by transportation. However, all pollution would be reduced substantially since transportation accounts for 75% of the carbon monoxide, 60% of the hydrocarbon, and 55% of the nitrogen oxide pollution in the nation. Problems related to the implementation of large-scale substitution are discussed.

  4. Quantitative Structure–Property Relationship (QSPR Models for a Local Quantum Descriptor: Investigation of the 4- and 3-Substituted-Cinnamic Acid Esterification

    Directory of Open Access Journals (Sweden)

    Cláudio E. Rodrigues-Santos

    2015-09-01

    Full Text Available In this work, the theoretical description of the 4- and 3-substituted-cinnamic acid esterification with different electron donating and electron withdrawing groups was performed at the B3LYP and M06-2X levels, as a two-step process: the O-protonation and the nucleophile attack by ethanol. In parallel, an experimental work devoted to the synthesis and characterization of the substituted-cinnamate esters has also been performed. In order to quantify the substituents effects, quantitative structure–property relationship (QSPR models based on the atomic charges, Fukui functions and the Frontier Effective-for-Reaction Molecular Orbitals (FERMO energies were investigated. In fact, the Fukui functions, ƒ+C and ƒ−O, indicated poor correlations for each individual step, and in contrast with the general literature, the O-protonation step is affected both by the FERMO energies and the O-charges of the carbonyl group. Since the process was shown to not be totally described by either charge- or frontier-orbitals, it is proposed to be frontier-charge-miscere controlled. Moreover, the observed trend for the experimental reaction yields suggests that the electron withdrawing groups favor the reaction and the same was observed for Step 2, which can thus be pointed out as the determining step.

  5. A New Substitution Cipher - Random-X

    Directory of Open Access Journals (Sweden)

    Falguni Patel

    2015-08-01

    Full Text Available Ciphers are the encryption methods to prepare the algorithm for encryption and decryption. The currently known ciphers are not strong enough to protect the data. A new substitution cipher Random-X that we introduce in this paper can be used for password encryption and data encryption. Random-X cipher is a unique substitution cipher which replaces the units of plaintext with triplets of letters. The beauty of this cipher is that the encrypted string of the same plain text is not always same. This makes it strong and difficult to crack. This paper covers the principle the implementation ideas and testing of Random-X cipher.

  6. Hydrophosphorylation of substituted alkynes by phosphonic acids

    International Nuclear Information System (INIS)

    Nifant'ev, E.F.; Solovetskaya, L.A.; Maslennikova, V.I.; Sergeev, N.M.

    1987-01-01

    Hydrophosphorylation of functionally substituted alkynes by phosphonic acids can be a convenient method for synthesis of functionally substituted mono- and diphosphine oxides. The ease of hydrophosphorylation is determined by the strength of the negative inductive effect of the substituents on the triple bond and the steric factor. The structure of the bis-adducts was confirmed by elementary analysis and the 31 P and 13 C NMR spectra. The 31 P NMR spectrum is an AB two-spin system. The values of the chemical shifts and spin-spin interaction constants 3 J/sub PP/ are in agreement with the data in the literature for similar compounds

  7. Substitution between cars within the household

    DEFF Research Database (Denmark)

    De Borger, Bruno; Mulalic, Ismir; Rouwendal, Jan

    The purpose of this paper is to study to what extent two-car households substitute the use of their less fuel efficient car by the use of their more fuel efficient car after an increase in fuel prices. Based on a simple theoretical framework we use a large sample of detailed Danish data on two-car...... households to estimate, for each car owned by the household, own and cross-price effects of increases in fuel costs per kilometer. The empirical results point at important substitution effects, so that models that estimate responses to fuel prices on the implicit or explicit assumption of one car per...

  8. Analysis of chemical equilibrium of silicon-substituted fluorescein and its application to develop a scaffold for red fluorescent probes.

    Science.gov (United States)

    Hirabayashi, Kazuhisa; Hanaoka, Kenjiro; Takayanagi, Toshio; Toki, Yuko; Egawa, Takahiro; Kamiya, Mako; Komatsu, Toru; Ueno, Tasuku; Terai, Takuya; Yoshida, Kengo; Uchiyama, Masanobu; Nagano, Tetsuo; Urano, Yasuteru

    2015-09-01

    Fluorescein is a representative green fluorophore that has been widely used as a scaffold of practically useful green fluorescent probes. Here, we report synthesis and characterization of a silicon-substituted fluorescein, i.e., 2-COOH TokyoMagenta (2-COOH TM), which is a fluorescein analogue in which the O atom at the 10' position of the xanthene moiety of fluorescein is replaced with a Si atom. This fluorescein analogue forms a spirolactone ring via intramolecular nucleophilic attack of the carboxylic group in a pH-dependent manner. Consequently, 2-COOH TM exhibits characteristic large pH-dependent absorption and fluorescence spectral changes: (1) 2-COOH TM is colorless at acidic pH, whereas fluorescein retains observable absorption and fluorescence even at acidic pH, and the absorption maximum is also shifted; (2) the absorption spectral change occurs above pH 7.0 for 2-COOH TM and below pH 7.0 for fluorescein; (3) 2-COOH TM shows a much sharper pH response than fluorescein because of its pKa inversion, i.e., pKa1 > pKa2. These features are also different from those of a compound without the carboxylic group, 2-Me TokyoMagenta (2-Me TM). Analysis of the chemical equilibrium between pH 3.0 and 11.0 disclosed that 2-COOH TM favors the colorless and nonfluorescent lactone form, compared with fluorescein. Substitution of Cl atoms at the 4' and 5' positions of the xanthene moiety of 2-COOH TM to obtain 2-COOH DCTM shifted the equilibrium so that the new derivative exists predominantly in the strongly fluorescent open form at physiological pH (pH 7.4). To demonstrate the practical utility of 2-COOH DCTM as a novel scaffold for red fluorescent probes, we employed it to develop a probe for β-galactosidase.

  9. Genome-Wide Bimolecular Fluorescence Complementation-Based Proteomic Analysis of Toxoplasma gondii ROP18’s Human Interactome Shows Its Key Role in Regulation of Cell Immunity and Apoptosis

    Directory of Open Access Journals (Sweden)

    Jing Xia

    2018-02-01

    Full Text Available Toxoplasma gondii rhoptry protein ROP18 (TgROP18 is a key virulence factor secreted into the host cell during invasion, where it modulates the host cell response by interacting with its host targets. However, only a few TgROP18 targets have been identified. In this study, we applied a high-throughput protein–protein interaction (PPI screening in human cells using bimolecular fluorescence complementation (BiFC to identify the targets of Type I strain ROP18 (ROP18I and Type II strain ROP18 (ROP18II. From a pool of more than 18,000 human proteins, 492 and 141 proteins were identified as the targets of ROP18I and ROP18II, respectively. Gene ontology, search tool for the retrieval of interacting genes/proteins PPI network, and Ingenuity pathway analyses revealed that the majority of these proteins were associated with immune response and apoptosis. This indicates a key role of TgROP18 in manipulating host’s immunity and cell apoptosis, which might contribute to the immune escape and successful parasitism of the parasite. Among the proteins identified, the immunity-related proteins N-myc and STAT interactor, IL20RB, IL21, ubiquitin C, and vimentin and the apoptosis-related protein P2RX1 were further verified as ROP18I targets by sensitized emission-fluorescence resonance energy transfer (SE-FRET and co-immunoprecipitation. Our study substantially contributes to the current limited knowledge on human targets of TgROP18 and provides a novel tool to investigate the function of parasite effectors in human cells.

  10. 2-Bromo-1,4-naphthoquinone: a potentially improved substitute of menadione in Apatone™ therapy

    Energy Technology Data Exchange (ETDEWEB)

    Graciani, F.S.; Ximenes, V.F. [Departamento de Química, Faculdade de Ciências, Universidade Estadual Paulista, Bauru SP (Brazil); Departamento de Análises Clínicas, Faculdade de Ciências Farmacêuticas, Universidade Estadual Paulista, Araraquara SP (Brazil)

    2012-05-18

    Apatone™, a combination of menadione (2-methyl-1,4-naphthoquinone, VK{sub 3}) and ascorbic acid (vitamin C, VC) is a new strategy for cancer treatment. Part of its effect on tumor cells is related to the cellular pro-oxidative imbalance provoked by the generation of hydrogen peroxide (H{sub 2}O{sub 2}) through naphthoquinone redox cycling. In this study, we attempted to find new naphthoquinone derivatives that would increase the efficiency of H{sub 2}O{sub 2} production, thereby potentially increasing its efficacy for cancer treatment. The presence of an electron-withdrawing group in the naphthoquinone moiety had a direct effect on the efficiency of H{sub 2}O{sub 2} production. The compound 2-bromo-1,4-naphthoquinone (BrQ), in which the bromine atom substituted the methyl group in VK{sub 3}, was approximately 10- and 19-fold more efficient than VK{sub 3} in terms of oxygen consumption and H{sub 2}O{sub 2} production, respectively. The ratio [H{sub 2}O{sub 2}]{sub produced} / [naphthoquinone]{sub consumed} was 68 ± 11 and 5.8 ± 0.2 (µM/µM) for BrQ and VK{sub 3}, respectively, indicating a higher efficacy of BrQ as a catalyst for the autoxidation of ascorbic acid. Both VK{sub 3} and BrQ reacted with glutathione (GSH), but BrQ was the more effective substrate. Part of GSH was incorporated into the naphthoquinone, producing a nucleophilic substitution product (Q-SG). The depletion of BrQ by GSH did not prevent its redox capacity since Q-SG was also able to catalyze the production of reactive oxygen species. VK{sub 3}/VC has already been submitted to clinical trials for the treatment of prostate cancer and has demonstrated promising results. However, replacement of VK{sub 3} with BrQ will open new lines of investigation regarding this approach to cancer treatment.

  11. Substituting freshwater: Can ocean desalination and water recycling capacities substitute for groundwater depletion in California?

    Science.gov (United States)

    Badiuzzaman, Pierre; McLaughlin, Eoin; McCauley, Darren

    2017-12-01

    While the sustainability of resource depletion is a longstanding environmental concern, wider attention has recently been given to growing water scarcity and groundwater depletion. This study seeks to test the substitutability assumption embedded in weak sustainability indicators using a case study of Californian water supply. The volume of groundwater depletion is used as a proxy for unsustainable water consumption, and defined by synthesising existing research estimates into low, medium and high depletion baselines. These are compared against projected water supply increases from ocean desalination and water recycling by 2035, to determine whether new, drought-proof water sources can substitute for currently unsustainable groundwater consumption. Results show that the maximum projected supply of new water, 2.47 million acre-feet per year (MAF/yr), is sufficient to meet low depletion estimates of 2.02 MAF/yr, but fails to come near the high depletion estimate of 3.44 MAF/yr. This does not necessarily indicate physical limitations of substitutability, but more so socio-economic limitations influenced by high comparative costs. By including capacities in demand-substitutability via urban water conservation, maximum predicted capacities reach 5.57 MAF/yr, indicating wide room for substitution. Based on these results, investment in social and institutional capital is an important factor to enhance demand-side substitutability of water and other natural resources, which has been somewhat neglected by the literature on the substitutability of natural resources. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Nucleophilic behavior of lysine-501 of the alpha-polypeptide of sodium and potassium ion activated adenosinetriphosphatase consistent with a role in binding adenosine triphosphate

    International Nuclear Information System (INIS)

    Xu, K.Y.; Kyte, J.

    1989-01-01

    An immunoadsorbent specific for the carboxy-terminal sequence -GAPER, which comprises residues 502-506 of the alpha-polypeptide of ovine sodium and potassium ion activated adenosinetriphosphatase [(Na+ + K+)-ATPase], was used to isolate the products of the reaction between the lysine immediately preceding this sequence in the intact protein and either [3H]acetic anhydride or fluorescein 5'-isothiocyanate. Changes in the apparent nucleophilicity of this lysine, Lys501, were observed with both reagents when ATP was bound by the intact, native enzyme poised in the E1 conformation or when the structure of the enzyme was changed from the E1 conformation into the E2-P conformation. With both reagents, a decrease of more than 4-fold in the yield of incorporation occurred during the former change, but a decrease of only 2-fold occurred during the latter. Because a much larger decrease occurred when ATP was bound in the absence of a conformational change than occurred when a major conformational change took place in the absence of the occupation of the active site, these changes in the incorporation of [3H]acetyl suggest that Lys501 from the alpha polypeptide is directly involved in binding ATP within the active site of (Na+ + K+)-ATPase. The immunochemical reactions between the specific polyclonal antibodies raised against the sequence-GAPER and denatured or enzymically active (Na+ + K+)-ATPase were also investigated. Western blots and the inhibition of enzymic activity caused by the antibody have shown that it can bind to both the denatured and the native form of the alpha-polypeptide, respectively

  13. P. Electricity demand, substitution and resources

    International Nuclear Information System (INIS)

    1976-01-01

    This report discusses the demand for electricity in New Zealand, the accuracy of demand predictions, and whether some other form of energy could be substituted for electricity. It then discusses past and possible future electricity generation in New Zealand by geothermal steam and hydro power and the resources of gas and coal that could be made available for electricity generation

  14. Endogenous cueing attenuates object substitution masking.

    Science.gov (United States)

    Germeys, Filip; Pomianowska, I; De Graef, P; Zaenen, P; Verfaillie, K

    2010-07-01

    Object substitution masking (OSM) is a form of visual masking in which a briefly presented target surrounded by four small dots is masked by the continuing presence of the four dots after target offset. A major parameter in the prediction of OSM is the time required for attention to be directed to the target following its onset. Object substitution theory (Di Lollo et al. in J Exp Psychol Gen 129:481-507, 2000) predicts that the sooner attention can be focused at the target's location, the less masking will ensue. However, recently Luiga and Bachmann (Psychol Res 71:634-640, 2007) presented evidence that precueing of attention to the target location prior to target-plus-mask onset by means of a central (endogenous) arrow cue does not reduce OSM. When attention was cued exogenously, OSM was attenuated. Based on these results, Luiga and Bachmann argued that object substitution theory should be adapted by differentiating the ways of directing attention to the target location. The goal of the present study was to further examine the dissociation between the effects of endogenous and exogenous precueing on OSM. Contrary to Luiga and Bachmann, our results show that prior shifts of attention to the target location initiated by both exogenous and endogenous cues reduce OSM as predicted by object substitution theory and its computational model CMOS.

  15. Substitute fluid examinations for liquid manure

    Directory of Open Access Journals (Sweden)

    Schrader Kevin

    2017-01-01

    Full Text Available For the farming industry it is essential to use liquid manure as natural fertilizer. Through new agricultural regulation 2015 in Germany the industry must develop new liquid manure spreader systems because the ammonia and methane emission are limited. In a research project the University of Applied Sciences Zwickau and some other industry partners will develop such a new innovative liquid manure spreader. The new liquid manure spreader should use pulsating air to distribute the liquid manure exactly. The pulsating air, which flows through the pipelines, should be analysed at a test station. For examinations at this test station it is important to find another substitute fluid because liquid manure smells strong, is not transparent and is also not homogeneous enough for scientific investigations. Furthermore it is important to ensure that the substitute fluid is, like liquid manure, a non-Newtonian fluid. The substitute fluid must be a shear-thinning substance - this means the viscosity decrease at higher shear rate. Many different samples like soap-water-farragoes, jelly-water-farragoes, agar-water-farragoes, soap-ethanol-farragoes and more are, for the project, examined in regard of their physical properties to find the best substitute fluid. The samples are examined at the rotational viscometer for viscosity at various shear rates and then compared with the viscosity values of liquid manure.

  16. Substitute fluid examinations for liquid manure

    Science.gov (United States)

    Schrader, Kevin; Riedel, Marco; Eichert, Helmut

    For the farming industry it is essential to use liquid manure as natural fertilizer. Through new agricultural regulation 2015 in Germany the industry must develop new liquid manure spreader systems because the ammonia and methane emission are limited. In a research project the University of Applied Sciences Zwickau and some other industry partners will develop such a new innovative liquid manure spreader. The new liquid manure spreader should use pulsating air to distribute the liquid manure exactly. The pulsating air, which flows through the pipelines, should be analysed at a test station. For examinations at this test station it is important to find another substitute fluid because liquid manure smells strong, is not transparent and is also not homogeneous enough for scientific investigations. Furthermore it is important to ensure that the substitute fluid is, like liquid manure, a non-Newtonian fluid. The substitute fluid must be a shear-thinning substance - this means the viscosity decrease at higher shear rate. Many different samples like soap-water-farragoes, jelly-water-farragoes, agar-water-farragoes, soap-ethanol-farragoes and more are, for the project, examined in regard of their physical properties to find the best substitute fluid. The samples are examined at the rotational viscometer for viscosity at various shear rates and then compared with the viscosity values of liquid manure.

  17. Trace maps for arbitrary substitution sequences

    International Nuclear Information System (INIS)

    Avishai, Y.

    1993-01-01

    The discovery of quasi-crystals and their 1-dimensional modeling have led to a deep mathematical study of Schroedinger operators with an arbitrary deterministic potential sequence. In this work we address this problem and find trace maps for an arbitrary substitution sequence. our trace maps have lower dimensionality than those of Kolar and Nori, which make them quite attractive for actual applications. (authors)

  18. Fossil Fuels, Backstop Technologies, and Imperfect Substitution

    NARCIS (Netherlands)

    van der Meijden, G.C.; Pittel, Karen; van der Ploeg, Frederick; Withagen, Cees

    2014-01-01

    This chapter studies the transition from fossil fuels to backstop technologies in a general equilibrium model in which growth is driven by research and development. The analysis generalizes the existing literature by allowing for imperfect substitution between fossil fuels and the new energy

  19. 3-Substituted 2-phenyl-indoles

    DEFF Research Database (Denmark)

    Johansson, Karl Henrik; Jørgensen, T.B.; Gloriam, D.E.

    2013-01-01

    -indoles with a variety of substituents at the indole 3-position. Herein we describe the development of optimised and efficient synthetic routes to a series of new 2-phenyl-indole building blocks 3 to 9 and show that these can be used to generate a broad variety of 3-substituted 2-phenyl-indoles of interest to medicinal...

  20. Law of substitution for mixed arrays

    International Nuclear Information System (INIS)

    Koudelka, A.J.

    1987-01-01

    The nuclear safety justification of a mixed array of dissimilar fissile units of metal units and dilute solution units, according to Clayton, has been a persistent and nagging problem. Dissimilar uranium metal or dissimilar uranium solution units in a mixed array can also create a modeling nightmare for the nuclear criticality safety engineer. Now, a calculational method known as the Law of Substitution has been developed to ensure that the k/sub eff/ of an array of uranium metal and uranium solution units will satisfy any k/sub eff/ limit set by the nuclear safety engineer. The nuclear criticality safety engineer can utilize the Law of Substitution to safely mix or substitute different uranium metal units, different uranium solution units, and more importantly, uranium metal and dilute UO 2 solution units in an array. The Law of Substitution is as follows: (1) calculate the k/sub eff/ of each unit type in its own infinite planar array. (2) Determine the edge-to-edge spacing of the infinite planar array of each type of unit to satisfy a desired k/sub eff/. (3) Select the largest edge-to-edge spacing from among the similar units in their infinite planar arrays and use that spacing for the finite or infinite planar array of mixed units

  1. Thermal stability of 4-substituted benzenediazonium tetrafluoroborates

    International Nuclear Information System (INIS)

    Bruner, V.Ya.

    1990-01-01

    Heating of tetraborates of 4-methyl-, 4-phenyl- and 4-dimethylaminobenzenediazonium at 95, 120 and 148 deg, correspondingly, causes their autocatalytic destruction, two moles of gas (nitrogen, boron fluoride) being liberated. The thermal stability of 4-substituted benzenediazonium tetrafluoroborates increases with the increase of the electron-donor activity of the substituent at benzene ring

  2. complexes based on meso-substituted dipyrrins

    Indian Academy of Sciences (India)

    Keywords. Coordination polymers; meso-substituted dipyrrins; heteroleptic; acetylacetonato; ... Room temperature magnetic susceptibility measurements were ... After cooling to ambient tem- perature it ... crystals of 1 were obtained from CH2Cl2/ hexane (1. : 1) solution. .... are air-stable, crystalline solids, soluble in common.

  3. Facile Synthesis of N -Substituted Benzimidazoles

    NARCIS (Netherlands)

    Kurhade, Santosh; Rossetti, Arianna; Dömling, Alexander

    2016-01-01

    A particularly mild and efficient one-pot synthesis of N-substituted benzimidazole derivatives was developed. 2-Fluoro-5-nitrophenylisocyanide reacts with a diverse set of primary amines to afford the respective products in moderate to very good yield (35-95%; 20 examples).

  4. Symptomatic hemorrhagic complications associated with dural substitutes

    Directory of Open Access Journals (Sweden)

    Po-Yuan Chen

    2018-01-01

    Conclusion: The increased risk of hemorrhagic complications associated with craniotomy is modified by choice of dural replacement. Our results could assist clinicians in their decision-making with respect to the optimal timing for synthetic dural substitutes in patients with tumor infiltration of the patient's dura, severe brain swelling in traumatic brain injury, or a result of shrinkage from exposure and electrocautery.

  5. Stochastic diffusion models for substitutable technological innovations

    NARCIS (Netherlands)

    Wang, L.; Hu, B.; Yu, X.

    2004-01-01

    Based on the analysis of firms' stochastic adoption behaviour, this paper first points out the necessity to build more practical stochastic models. And then, stochastic evolutionary models are built for substitutable innovation diffusion system. Finally, through the computer simulation of the

  6. Ultrasound Promoted Synthesis of Bis(substituted pyrazol-4-ylcarbonyl-Substituted Thioureas

    Directory of Open Access Journals (Sweden)

    Li Xiao

    2009-03-01

    Full Text Available A series of novel bis(substituted pyrazol-4-ylcarbonyl-substituted thioureas have been synthesized by the reactions of substituted pyrazol-4-ylcarbonyl isothiocyanates with different diamines under ultrasound irradiation and classical heating method at 20-25 °C. In general, substantial improvement in rates and modest yields increases were observed when reactions were carried out under sonication, compared with the classical heating method. The structures of these compounds have been elucidated by elemental and spectral (IR, 1H-NMR analysis.

  7. Currency Substitution and Inflation in Peru Currency Substitution and Inflation in Peru

    OpenAIRE

    Liliana Rojas-Suarez

    1992-01-01

    This paper shows that there is a long-run relationship between the expected rate of depreciation in the black-market-exchange rate and the ratio of domestic to foreign money in Peru: that is, the hypothesis of currency substitution can explain the behavior of real holdings of money in Peru. The paper also shows that, while, the importance of currency substitution as a transmission mechanism through which domestic policies affected the dynamics of inflation was relatively small during a period...

  8. Substitution treatment for opioid addicts in Germany

    Directory of Open Access Journals (Sweden)

    Gerlach Ralf

    2007-02-01

    Full Text Available Abstract Background After a long and controversial debate methadone maintenance treatment (MMT was first introduced in Germany in 1987. The number of patients in MMT – first low because of strict admission criteria – increased considerably since the 1990s up to some 65,000 at the end of 2006. In Germany each general practitioner (GP, who has completed an additional training in addiction medicine, is allowed to prescribe substitution drugs to opioid dependent patients. Currently 2,700 GPs prescribe substitution drugs. Psychosocial care should be made available to all MMT patients. Results The results of research studies and practical experiences clearly indicate that patients benefit substantially from MMT with improvements in physical and psychological health. MMT proves successful in attaining high retention rates (65 % to 85 % in the first years, up to 50 % after more than seven years and plays a major role in accessing and maintaining ongoing medical treatment for HIV and hepatitis. MMT is also seen as a vital factor in the process of social re-integration and it contributes to the reduction of drug related harms such as mortality and morbidity and to the prevention of infectious diseases. Some 10 % of MMT patients become drug-free in the long run. Methadone is the most commonly prescribed substitution medication in Germany, although buprenorphine is attaining rising importance. Access to MMT in rural areas is very patchy and still constitutes a problem. There are only few employment opportunities for patients participating in MMT, although regular employment is considered unanimously as a positive factor of treatment success. Substitution treatment in German prisons is heterogeneous in access and treatment modalities. Access is very patchy and the number of inmates in treatment is limited. Nevertheless, substitution treatment plays a substantial part in the health care system provided to drug users in Germany. Conclusion In Germany, a

  9. Substitution treatment for opioid addicts in Germany.

    Science.gov (United States)

    Michels, Ingo Ilja; Stöver, Heino; Gerlach, Ralf

    2007-02-02

    After a long and controversial debate methadone maintenance treatment (MMT) was first introduced in Germany in 1987. The number of patients in MMT--first low because of strict admission criteria--increased considerably since the 1990s up to some 65,000 at the end of 2006. In Germany each general practitioner (GP), who has completed an additional training in addiction medicine, is allowed to prescribe substitution drugs to opioid dependent patients. Currently 2,700 GPs prescribe substitution drugs. Psychosocial care should be made available to all MMT patients. The results of research studies and practical experiences clearly indicate that patients benefit substantially from MMT with improvements in physical and psychological health. MMT proves successful in attaining high retention rates (65% to 85% in the first years, up to 50% after more than seven years) and plays a major role in accessing and maintaining ongoing medical treatment for HIV and hepatitis. MMT is also seen as a vital factor in the process of social re-integration and it contributes to the reduction of drug related harms such as mortality and morbidity and to the prevention of infectious diseases. Some 10% of MMT patients become drug-free in the long run. Methadone is the most commonly prescribed substitution medication in Germany, although buprenorphine is attaining rising importance. Access to MMT in rural areas is very patchy and still constitutes a problem. There are only few employment opportunities for patients participating in MMT, although regular employment is considered unanimously as a positive factor of treatment success. Substitution treatment in German prisons is heterogeneous in access and treatment modalities. Access is very patchy and the number of inmates in treatment is limited. Nevertheless, substitution treatment plays a substantial part in the health care system provided to drug users in Germany. In Germany, a history of substitution treatment spanning 20 years has meanwhile

  10. [The substitution effect of leadership substitutes for transformational leadership in nursing organization].

    Science.gov (United States)

    Kim, Jeong-Hee

    2006-04-01

    This paper was conducted to examine the effects of transformational leadership behaviors, within the substitutes for leadership model (Kerr & Jermier, 1978). Data was collected from 181 staff nurses in 3 general hospitals, with self-reporting questionnaires (MLQ developed by Bass, rd-SLS developed by Podsakoff, et al., and MSQ developed by Weiss, et al.). Descriptive statistics, factor analysis, Cronbach's alpha and moderated regression analysis were used. 1) The transformational leader behaviors and substitutes for leadership each had correlations with job satisfaction. 2) The total amount of variance accounted for by the substitutes for leadership was substantially greater than by the transformational leadership behaviors. 3) Few of the substitutes variables moderated the relationships between the transformational leader behaviors and job satisfaction in a manner consistent with that specified by Howell, Dorfman, and Kerr (1986). The finding of this study suggest that leaders need to have a better understanding of those contextual variables that influence job satisfaction. Thus future research should focus attention on the moderating effects of substitutes, as well as the things that leaders can do to influence them. In addition, it may be good to examine the effects of substitutes on other criterion variables.

  11. SUBSTITUTION OF CADMIUM CYANIDE ELECTROPLATING WITH ZINC CHLORIDE ELECTROPLATING

    Science.gov (United States)

    The study evaluated the zinc chloride electroplating process as a substitute for cadmium cyanide electroplating in the manufacture of industrial connectors and fittings at Aeroquip Corporation. The process substitution eliminates certain wastes, specifically cadmium and cyanide, ...

  12. Characterization of hydroxyapatite substituted with silicon

    International Nuclear Information System (INIS)

    Silva, H.M. da; Soares, G.A.; Mateescu, M.; Anselme, K.; Palard, M.; Champion, E.

    2009-01-01

    Incorporation of silicon (Si) ions into hydroxyapatite structure (HA) influences on physical, chemical and physiological properties. Some studies reported the improved bioactivity Si substitution, and it also accelerates the biomineralization process. The main objective of this work is to characterize stoichiometric hydroxyapatite and hydroxyapatite substituted with 1.13% in weight of Si (SiHA) using a wet precipitation method followed by a heat treatment. SEM/EDS, AFM, DRX and FTIR analyses were used to characterize the samples. EDS and FTIR results confirmed the presence of Si. Silicon induces small changes on crystal structure of HA, not detected on X-ray diffraction patterns of sintered tablets of SiHA and HA. No secondary phases were observed, that indicates the Si had entered the HA lattice. (author)

  13. The substitution bias of the consumer price index

    OpenAIRE

    Frenger, Petter

    2006-01-01

    Abstract: The paper uses elementary consumer theory to propose an inflation independent ratio definition of the substitution bias of the Laspeyres consumer price index, and derives an approximate substitution bias which depends on the size of the price change as measured by a norm in the Laspeyres plane and on the elasticity of substitution in the direction of the price change. This norm or distance measure can be interpreted as a price substitution index which yields useful in...

  14. Unemployment, Factor Substitution, and Capital Formation

    OpenAIRE

    Leo Kaas; Leopold von Thadden

    2001-01-01

    We incorporate a wage bargaining structure in a dynamic general equilibrium model and show how this feature changes short and long-run properties of equilibria compared with a perfectly competitive setting. We discuss how employment, capital, and income shares respond to wage setting shocks and show that adjustment dynamics depend decisively on the magnitude of the elasticity of substitution between labour and capital. Values of the elasticity below unity add persistence, tend to preserve sta...

  15. Mindfulness as substitute for transformational leadership

    OpenAIRE

    Kroon, B.; van Woerkom, M.; Menting, Charlotte

    2017-01-01

    Purpose Transformational leaders spark the intrinsic motivation of employees, thereby stimulating their extra-role performance. However, not all employees are lucky enough to have a transformational leader. The purpose of this paper is to investigate to what extent mindfulness can function as a substitute for transformational leadership. By being attentive to and aware of what is taking place in the present, mindfulness provides employees with a source of intrinsic motivation that lies within...

  16. Neutron scattering from a substitutional mass defect

    International Nuclear Information System (INIS)

    Williams, R.D.; Lovesey, S.W.

    1985-06-01

    The dynamic structure factor is calculated for a low concentration of light mass scatterers substituted in a cubic crystal matrix. A new numerical method for the exact calculation is demonstrated. A local density of states for the low momentum transfer limit, and the shifts and widths of the oscillator peaks in the high momentum transfer limit are derived. The limitations of an approximation which decouples the defect from the lattice is discussed. (author)

  17. Substitution biases in price indices during transition

    Czech Academy of Sciences Publication Activity Database

    Hanousek, Jan; Filer, Randall K.

    2004-01-01

    Roč. 21, č. 2 (2004), s. 167-177 ISSN 0167-8000 R&D Projects: GA MŠk ME 595 Institutional research plan: CEZ:AV0Z7085904 Keywords : price liberalization * substitution bias * transition economies Subject RIV: AH - Economics http://search. ebscohost .com/login.aspx?direct=true&db=a9h&AN=17109091&site=ehost-live

  18. Synthesis of 2-azetidinones substituted quinoline derivative

    Directory of Open Access Journals (Sweden)

    Mashelkar Uday C.

    2013-01-01

    Full Text Available Acetanilide is converted into 2-chloro-3-formyl quinoline by reacting with DMF-POCl3 at 80-90ºC and then condensed with aromatic primary amines to give Schiff bases (3a-3c. These Schiff bases are then reacted with acid chlorides in the presence of base in toluene to give 1, 3, 4-substituted 2-azetidinones.

  19. Interfuel substitution in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Serletis, Apostolos; Vasetsky, Olexandr [Department of Economics, University of Calgary, Calgary, Alberta (Canada); Timilsina, Govinda R. [Development Research Group, The World Bank, 1818 H Street N.W., Washington, DC 20433 (United States)

    2010-05-15

    In this paper, we use the locally flexible translog functional form to investigate the demand for energy and interfuel substitution in the United States and to provide a comparison of our results with most of the existing empirical energy demand literature. Motivated by the widespread practice of ignoring theoretical regularity, we follow Barnett's (2002) suggestions and estimate the model subject to theoretical regularity, using methods developed by Diewert and Wales (1987) and Ryan and Wales (2000), in an attempt to produce inference consistent with neoclassical microeconomic theory. Moreover, we use the most recent data, published by the U.S. Energy Information Administration (EIA), and in addition to investigating interfuel substitution possibilities in total U.S. energy demand, we follow Serletis et al. (2009) and also examine interfuel substitution possibilities in energy demand by sector. Moreover, we test for weak separability, with the objective of discovering the structure of the functional form in total energy demand as well as energy demand by sector. (author)

  20. 40 CFR 721.4596 - Diazo substituted carbomonocyclic metal complex.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Diazo substituted carbomonocyclic... Specific Chemical Substances § 721.4596 Diazo substituted carbomonocyclic metal complex. (a) Chemical... as a diazo substituted carbomonocyclic metal complex (PMN P-94-1039) is subject to reporting under...

  1. 40 CFR 721.5350 - Substituted nitrile (generic name).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Substituted nitrile (generic name... Substances § 721.5350 Substituted nitrile (generic name). (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as a substituted nitrile (PMN P-83...

  2. 40 CFR 721.10043 - Dineopentyl-4-substituted phthalate (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Dineopentyl-4-substituted phthalate... Specific Chemical Substances § 721.10043 Dineopentyl-4-substituted phthalate (generic). (a) Chemical... as dineopentyl-4-substituted phthalate (PMN P-02-697) is subject to reporting under this section for...

  3. Stereoinversion of tertiary alcohols to tertiary-alkyl isonitriles and amines.

    Science.gov (United States)

    Pronin, Sergey V; Reiher, Christopher A; Shenvi, Ryan A

    2013-09-12

    The SN2 reaction (bimolecular nucleophilic substitution) is a well-known chemical transformation that can be used to join two smaller molecules together into a larger molecule or to exchange one functional group for another. The SN2 reaction proceeds in a very predictable manner: substitution occurs with inversion of stereochemistry, resulting from the 'backside attack' of the electrophilic carbon by the nucleophile. A significant limitation of the SN2 reaction is its intolerance for tertiary carbon atoms: whereas primary and secondary alcohols are viable precursor substrates, tertiary alcohols and their derivatives usually either fail to react or produce stereochemical mixtures of products. Here we report the stereochemical inversion of chiral tertiary alcohols with a nitrogenous nucleophile facilitated by a Lewis-acid-catalysed solvolysis. The method is chemoselective against secondary and primary alcohols, thereby complementing the selectivity of the SN2 reaction. Furthermore, this method for carbon-nitrogen bond formation mimics a putative biosynthetic step in the synthesis of marine terpenoids and enables their preparation from the corresponding terrestrial terpenes. We expect that the general attributes of the methodology will allow chiral tertiary alcohols to be considered viable substrates for stereoinversion reactions.

  4. Annonaceae substitution rates: a codon model perspective

    Directory of Open Access Journals (Sweden)

    Lars Willem Chatrou

    2014-01-01

    Full Text Available The Annonaceae includes cultivated species of economic interest and represents an important source of information for better understanding the evolution of tropical rainforests. In phylogenetic analyses of DNA sequence data that are used to address evolutionary questions, it is imperative to use appropriate statistical models. Annonaceae are cases in point: Two sister clades, the subfamilies Annonoideae and Malmeoideae, contain the majority of Annonaceae species diversity. The Annonoideae generally show a greater degree of sequence divergence compared to the Malmeoideae, resulting in stark differences in branch lengths in phylogenetic trees. Uncertainty in how to interpret and analyse these differences has led to inconsistent results when estimating the ages of clades in Annonaceae using molecular dating techniques. We ask whether these differences may be attributed to inappropriate modelling assumptions in the phylogenetic analyses. Specifically, we test for (clade-specific differences in rates of non-synonymous and synonymous substitutions. A high ratio of nonsynonymous to synonymous substitutions may lead to similarity of DNA sequences due to convergence instead of common ancestry, and as a result confound phylogenetic analyses. We use a dataset of three chloroplast genes (rbcL, matK, ndhF for 129 species representative of the family. We find that differences in branch lengths between major clades are not attributable to different rates of non-synonymous and synonymous substitutions. The differences in evolutionary rate between the major clades of Annonaceae pose a challenge for current molecular dating techniques that should be seen as a warning for the interpretation of such results in other organisms.

  5. Alkylation of N-substituted 2-phenylacetamides

    Directory of Open Access Journals (Sweden)

    SLOBODAN D. PETROVIC

    2004-10-01

    Full Text Available Various N-substituted phenylacetamides were alkylated using different alkylating agents under neutral and basic conditions. Reactions were performed at different reaction temperatures and in various solvents. Also, a number of various catalysts were used including phase-transfer catalysts. Reactions were followed using GC or GC-MS technique and the presence as well as the yields of the alkylation products were established. Generally, the best yield and high selectivity in the studied reactions were achieved under basic conditions where in the certain cases some products, mostly N-product, were obtained solely in quantitative yields.

  6. Mechanistic studies on β-ketoacyl thiolase from Zoogloea ramigera: Identification of the active-site nucleophile as Cys89, its mutation to Ser89, and kinetic and thermodynamic characterization of wild-type and mutant enzymes

    International Nuclear Information System (INIS)

    Thompson, S.; Mayerl, F.; Walsh, C.T.; Peoples, O.P.; Masamune, S.; Sinskey, A.J.

    1989-01-01

    Thiolase proceeds via covalent catalysis involving an acetyl-S-enzyme. The active-site thiol nucleophile is identified as Cys 89 by acetylation with [ 14 C]acetyl-CoA, rapid denaturation, tryptic digestion, and sequencing of the labeled peptide. The native acetyl enzyme is labile to hydrolytic decomposition with t 1/2 of 2 min at pH 7, 25 degree C. Cys 89 has been converted to the alternate nucleophile Ser 89 by mutagenesis and the C89S enzyme overproduced, purified, and assessed for activity. The Ser 89 enzyme retains 1% of the V max of the Cys 89 enzyme in the direction of acetoacetyl-CoA thiolytic cleavage and 0.05% of the V max in the condensation of two acetyl-CoA molecules. A covalent acetyl-O-enzyme intermediate is detected on incubation with [ 14 C]acetyl-CoA and isolation of the labeled Ser 89 -containing tryptic peptide. Comparisons of the Cys 89 and Ser 89 enzymes have been made for kinetic and thermodynamic stability of the acetyl enzyme intermediates both by isolation and by analysis of [ 32 P]CoASH/acetyl-CoA partial reactions and for rate-limiting steps in catalysis with trideuterioacetyl-CoA

  7. Advances in Osteobiologic Materials for Bone Substitutes.

    Science.gov (United States)

    Hasan, Anwarul; Byambaa, Batzaya; Morshed, Mahboob; Cheikh, Mohammad Ibrahim; Shakoor, Rana Abdul; Mustafy, Tanvir; Marei, Hany

    2018-04-27

    A significant challenge in the current orthopedics is the development of suitable osteobiologic materials that can replace the conventional allografts, autografts and xenografts, and thereby serve as implant materials as bone substitutes for bone repair or remodeling. The complex biology behind the nano-microstructure of bones and their repair mechanisms, which involve various types of chemical and biomechanical signaling amongst different cells, has set strong requirements for biomaterials to be used in bone tissue engineering. This review presents an overview of various types of osteobiologic materials to facilitate the formation of the functional bone tissue and healing of the bone, covering metallic, ceramic, polymeric and cell-based graft substitutes, as well as some biomolecular strategies including stem cells, extracellular matrices, growth factors and gene therapies. Advantages and disadvantages of each type, particularly from the perspective of osteoinductive and osteoconductive capabilities, are discussed. Although the numerous challenges of bone regeneration in tissue engineering and regenerative medicine are yet to be entirely addressed, further advancements in osteobiologic materials will pave the way towards engineering fully functional bone replacement grafts. This article is protected by copyright. All rights reserved.

  8. Pressure-induced polymerization in substituted acetylenes

    Energy Technology Data Exchange (ETDEWEB)

    Chellappa, Raja S.; Dattelbaum, Dana M.; Sheffield, Stephen; Robbins, David (LANL)

    2012-04-10

    A fundamental understanding of shock-induced chemical reactions in organics is still lacking and there are limited studies devoted to determining reaction mechanisms, evolution of bonding, and effect of functional group substitutions. The fast timescale of reactions occurring during shock compression create significant experimental challenges (diagnostics) to fully quantify the mechanisms involved. Static compression combined with temperature provides a complementary route to investigate the equilibrium phase space and metastable intermediates under extreme P-T conditions. In this study, we present our results from our ongoing high pressure in situ synchrotron x-ray diffraction experiments on substituted acetylenes: tert-butyl acetylene [TBA: (CH{sub 3}){sub 3}-C=CH] and ethynyl trimethylsilane [ETMS: (CH{sub 3}){sub 3}-SiC=CH]. We observed that the onset pressure of chemical reactions (at room temperature) in these compounds is higher under static compression (TBA: 12 GPa and ETMS: 17.6 GPa) when compared to shock input pressures (TBA: 6.1 GPa and ETMS: 6.6 GPa). At elevated temperatures, reactivity was observed to occur at pressures comparable to shock conditions. The products were polymeric in nature, recovered to ambient conditions with little degradation.

  9. Challenges in drug discovery for thiazolidinedione substitute

    Directory of Open Access Journals (Sweden)

    Jian-ping Ye

    2011-10-01

    Full Text Available Thiazolidinedione (TZD is a powerful insulin sensitizer in the treatment of type 2 diabetes. It acts as a ligand to the nuclear receptor PPARγ (peroxisome proliferator-activated receptor-gamma and induces transcription of PPARγ-responsive genes. TZD controls lipid synthesis and storage in adipose tissue, liver and many other tissues through PPARγ. Derivatives of TZD, such as rosiglitazone (Avandia and pioglitazone (Actos, are more powerful than metformin or berberine in insulin sensitization. Although they have common side effects such as weight gain and edema, these did not influence their clinical application in general. However, recent findings of risk for congestive heart failure and bladder cancer have significantly impaired their future in many countries. European countries have prohibited those drugs, and US will terminate application of rosiglitazone in clinics and hospitals. The multiple country actions may mark the end of TZD era. As a result, there is a strong demand for identification of TZD substitute in the treatment of type 2 diabetes. In this regard, literature about PPARγ ligands and potential TZD substitute are reviewed in this article. Histone deacetylase (HDAC inhibitor is emphasized as a new class of insulin sensitizer here. Regulators of SIRT1, CREB, NO, p38, ERK and Cdk5 are discussed in the activation of PPARγ.

  10. Substitution of thoriated tungsten electrodes in Switzerland

    International Nuclear Information System (INIS)

    Kunz, H.; Piller, G.

    2006-01-01

    Thoriated tungsten electrodes are frequently used for inert gas welding (TIG/WIG). The use of these electrodes can lead to doses which are well above the limit for the general population (1mSv/year). This has been shown by different investigations, for example from the ''Berufsgenossenschaft''. With these findings in mind, the regulatory authorities (Swiss Federal Office of Public Health (SFOPH) and Swiss National Accident Insurance Association (Suva)) started in 1999 to examine the justification of thoriated tungsten electrodes and a possible substitution with products containing no radioactive material. Up to this time, the use of thoriated tungsten electrodes could be justified since no thorium-free products leading to comparable results were available on the market. This was also the reason why the SFOPH approved several types of these electrodes. Discussions with formation centers for welding and inquiries made at welding shops, trading companies and producers showed that in the mean-time thorium-free products with comparable welding specifications and results became available on the market. Since the 1 January 2004, thoriated tungsten electrodes can only be used if the user has obtained the corresponding license from the SFOPH. The use of thoriated tungsten electrodes is thus not completely forbidden, but very strict conditions have to be fulfilled. Up to now and due to the involvement of the relevant partners, the substitution process has not met any problem. Neither trading companies nor users made any opposition and no request for obtaining a license for thoriated tungsten electrodes was made. (orig.)

  11. Reaction of singlet-excited 2,3-diazabicyclo[2.2.2]oct-2-ene and tert-butoxyl radicals with aryl-substituted benzofuranones.

    Science.gov (United States)

    Lundgren, Cecilia Vannesjö; Koner, Apurba L; Tinkl, Michael; Pischel, Uwe; Nau, Werner M

    2006-03-03

    5,7-Di-tert-butyl-3-aryl-3H-benzofuran-2-ones are lactones with potential antioxidant activity, owing to their abstractable benzylic C-H hydrogens. The fluorescence quenching of the azoalkane 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO), an established probe for the hydrogen-donor propensity of chain-breaking antioxidants, was investigated for 16 aryl-substituted benzofuranone derivatives [m,m-(CF3)2, p-CN, m-CN, p-CF3, p-COOCH3, m-CF3, p-Cl, p-F, H, m-CH3, p-CH3, m,p-(CH3)2, p-OCH3, o-CH3, o-CF3, o,m-(CH3)2]. Analysis of the rate data in terms of a linear free energy relationship yielded a reaction constant of rho = +0.35. This implies that n,pi*-excited DBO acts as nucleophilic species. In contrast, hydrogen abstraction of tert-butoxyl radicals from the benzofuranones was accelerated by electron-donating substituents (rho = -0.23), in conformity with the electrophilic character of oxygen-centered alkoxyl radicals. Possible implications for the optimization of the hydrogen-donor propensity of antioxidants through structural variation are discussed.

  12. Perron-Frobenius theory and frequency convergence for reducible substitutions

    OpenAIRE

    Lustig, Martin; Uyanik, Caglar

    2016-01-01

    We prove a general version of the classical Perron-Frobenius convergence property for reducible matrices. We then apply this result to reducible substitutions and use it to produce limit frequencies for factors and hence invariant measures on the associated subshift. The analogous results are well known for primitive substitutions and have found many applications, but for reducible substitutions the tools provided here were so far missing from the theory.

  13. Goods-Time Elasticity of Substitution in Health Production.

    Science.gov (United States)

    Du, Juan; Yagihashi, Takeshi

    2017-11-01

    We examine how inputs for health production, in particular, medical care and health-enhancing time, are combined to improve health. The estimated elasticity of substitution from a constant elasticity of substitution production function is significantly less than one for the working-age population, rejecting the unit elasticity of substitution used in previous studies. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  14. Import Substitution in Regional Industrial Production: Theoretical and Practical Aspects

    Directory of Open Access Journals (Sweden)

    Yevgeniy Georgievich Animitsa

    2015-09-01

    Full Text Available The article proves the important role of import substitution in the economic security protection of state and its regions, especially in times of crisis, geopolitical and economical instability. The authors argue that the problem of import substitution is not modern, trendy scientific stream. The issue of displacement of import goods by domestic ones was brought up in famous classic theories of mercantilists. The particular emphasis is placed on the analysis and systematization of different scientific approaches, which are utilized by native and foreign scientists to bring out the matter of “import substitution,” to determine its essential characteristics. The authors suggest their own interpretation of the import substitution notion. In the article, the most significant pro and contra arguments in import substitution policy are defined. The regional aspects in the import substitution are approved: case study — organization of industrial import substitution in the Sverdlovsk region. In the article, the authors analyze the subject matter of the Program “Development of Intraregional Industrial Cooperation and Implementation of an Import Substitution in Branches of Industry in the Sverdlovsk Region.” It is resumed, that active policy of import substitution in the industry may become the driver of regional economic development.

  15. Zinc and Carbonate Co-Substituted Nano-Hydroxyapatite

    Science.gov (United States)

    Girija, E. K.; Kumar, G. Suresh; Thamizhavel, A.

    2011-07-01

    Synthesis of Zn or CO32- substituted nano-hydroxyapatite (HA) and its physico-chemical properties have been well documented. However, the effects of the simultaneous substitution of Zn and CO32- in nano-HA have not been reported. In the present study, Zn and CO32- substitutions in nano HA independently and concurrently have been done by wet precipitation method and characterized by XRD and FT-IR for its phase purity and chemical homogeneity. Further modulations of the bioactivity and thermal stability of HA due to the substitutions have been studied.

  16. Technological substitution options for controlling greenhouse gas emissions

    International Nuclear Information System (INIS)

    Barbier, E.B.; Burgess, J.C.; Pearce, D.W.

    1991-01-01

    This chapter is concerned with technological options for greenhouse gas substitution. The authors interpret the term substitution to exclude energy conservation/efficiency measures, investments in afforestation (sinks), and greenhouse gas removal or abatement technologies. Their working definition of greenhouse gas substitution includes (1) replacement technologies, for example, substituting a greenhouse gas technology with a nongreenhouse gas technology; and (2) reduction technologies, for example, substituting a greenhouse gas technology with an alternative technology that reduces greenhouse gas emissions. Essentially, replacement technologies involve 100 percent reduction in CO 2 ; reduction technologies involve a partial reduction in CO 2 . Of the man-made sources of greenhouse gases, energy is the most important and is expected to contribute to at least half of the global warming effect in the near future. The majority of this impact is from fossil fuel combustion as a source of carbon dioxide (CO 2 ), although fossil fuels also contribute significantly to methane (CH 4 ), to nitrous oxide (N 2 O), and to low-level ozone (O 3 ) through production of various nitrogen gases (NO x ) and carbon monoxide (CO). This study analyzes the available greenhouse gas substitutions and their costs. The authors concentrate particularly on substitutions for fossil-fuel combustion and CFC production and consumption. They conclude by summarizing the potential for greenhouse gas substitution, the cost-effectiveness of the various options and the design of incentives for substitution

  17. Time and Money - Are they Substitutes?

    DEFF Research Database (Denmark)

    Bonke, Jens; Deding, Mette; Lausten, Mette

    In this paper, we analyse the distribution of time and money for Danish wage earner couples, where time is defined as leisure time and money as extended income, i.e. the sum of disposable income and the value of housework. The hypothesis is that individuals being rich in one dimension are more...... likely to be poor in the other dimension, such that individuals can be classified as either money-poor/time-rich or money-rich/time-poor. We analyse two different distributions of income, where the first assumes no sharing and the second complete sharing of income between spouses. The data are from...... the Danish Time-Use Survey 2001, merged with register data. Results show that the substitution of money for time is more prominent for women than for men, because they have a larger income share of time-intensive value of housework, while men have the larger share of disposable income. Furthermore, when...

  18. SYNTHESIS OF SUBSTITUTED QUINOLINE-3-CARBALDEHYDES

    Directory of Open Access Journals (Sweden)

    L. G. Klad'ko

    2015-12-01

    Full Text Available Dehalogenation of а series substituted 2-chloroquinoline-3-carbaldehydes was investigated. It was found that zinc dust in alkali ethanol practically do not react with 2-chloro-3-(1,3-dioxolan-2-yl-7-methylquinolines for a 5 day at ambient temperature. Increase temperature to boiling point of reaction mixture lead to increase yield 7-methylquinoline-3-carbaldehyde to 12.5%. This reaction with 2-chloro-3-dimetoxymetyl-7-methylquinoline give 26.5 above aldehyde. Replacement of ethanol to methanol give only traces of desired aldehyde. Neither 2-chloro-7-methylquinoline-3-carbaldehyde, nor his acetals do not react with sodium dithionite. Furthermore for activation of halogen we replaced chloraldehydes to iodoaldehydes by Finkelstein reaction, then protect aldehyde function by formation of dimethylacetals and treatment his by sodium dithionite in mixture pyridine-water. Desired aldehydes was obtained with poor to moderate yields. Increasing yields of this reaction is goal our further investigations.

  19. Porous bioresorbable magnesium as bone substitute

    Energy Technology Data Exchange (ETDEWEB)

    Wen, C.E.; Yamada, Y.; Shimojima, K.; Chino, Y.; Hosokawa, H.; Mabuchi, M. [Inst. for Structural and Engineering Materials, National Inst. of Advanced Industrial Science and Technology, Nagoya (Japan)

    2003-07-01

    Recently magnesium has been recognized as a very promising biomaterial for bone substitutes because of its excellent properties of biocompatibility, biodegradability and bioresorbability. In the present study, magnesium foams were fabricated by using a powder metallurgical process. Scanning electron microscopy equipped with energy dispersive X-ray spectrometer (EDS) and compressive tester were used to characterize the porous magnesium. Results show that the Young's modulus and the peak stress of the porous magnesium increase with decreasing porosity and pore size. This study suggests that the mechanical properties of the porous magnesium with the low porosity of 35% and/or with the small pore size of about 70 {mu}m are close to those of human cancellous bones. (orig.)

  20. Substitution reactions of carbon nanotube template

    Science.gov (United States)

    Li, Chi Pui; Chen, Ying; Gerald, John Fitz

    2006-05-01

    Substitution reactions between carbon nanotube (CNT) template and SiO with the formation of carbon rich silicon oxide nanowires (SiO-C-NWs) have been investigated using transmission electron microscopy and x-ray energy dispersive spectroscopy. The reaction was carried out by thermal annealing at 1200°C for 1h of a mixture of silicon monoxide (SiO) and iron (II) phthalocyanine, FeC32N8H16 (FePc) powders. Multiwalled CNTs were produced first via pyrolysis of FePc at a lower temperature (1000°C ). SiO vapors reacted with the CNTs at higher temperatures to produce amorphous SiO-C-NWs with a uniform diameter and a length in tens of micrometers. The special bamboolike structure of the CNTs allows the reaction to start from the external surface of the tubes and transform each CNT into a solid nanowire section by section.

  1. Packing and Disorder in Substituted Fullerenes

    KAUST Repository

    Tummala, Naga Rajesh

    2016-07-15

    Fullerenes are ubiquitous as electron-acceptor and electron-transport materials in organic solar cells. Recent synthetic strategies to improve the solubility and electronic characteristics of these molecules have translated into a tremendous increase in the variety of derivatives employed in these applications. Here, we use molecular dynamics (MD) simulations to examine the impact of going from mono-adducts to bis- and tris-adducts on the structural, cohesive, and packing characteristics of [6,6]-phenyl-C60-butyric acid methyl ester (PCBM) and indene-C60. The packing configurations obtained at the MD level then serve as input for density functional theory calculations that examine the solid-state energetic disorder (distribution of site energies) as a function of chemical substitution. The variations in structural and site-energy disorders reflect the fundamental materials differences among the derivatives and impact the performance of these materials in thin-film electronic devices.

  2. Crossmodal Perceptual Learning and Sensory Substitution

    Directory of Open Access Journals (Sweden)

    Michael J Proulx

    2011-10-01

    Full Text Available A sensory substitution device for blind persons aims to provide the missing visual input by converting images into a form that another modality can perceive, such as sound. Here I will discuss the perceptual learning and attentional mechanisms necessary for interpreting sounds produced by a device (The vOICe in a visuospatial manner. Although some aspects of the conversion, such as relating vertical location to pitch, rely on natural crossmodal mappings, the extensive training required suggests that synthetic mappings are required to generalize perceptual learning to new objects and environments, and ultimately to experience visual qualia. Here I will discuss the effects of the conversion and training on perception and attention that demonstrate the synthetic nature of learning the crossmodal mapping. Sensorimotor experience may be required to facilitate learning, develop expertise, and to develop a form of synthetic synaesthesia.

  3. Magnetic disaccommodation in Sn substituted magnetite

    International Nuclear Information System (INIS)

    Hernandez-Gomez, P.; Bendimya, K.; Francisco, C. de; Munoz, J.M.; Alejos, O.; Torres, C.

    2001-01-01

    The relaxation of the initial magnetic permeability has been measured in polycrystalline Sn-doped magnetite with nominal composition Sn x Fe 3-x O 4 with x ranging from x=0 to 0.6. In the temperature range between 80 and 500 K, the time decay of the initial permeability after sample demagnetization has been represented by means of isochronal disaccommodation curves, which show the presence of different relaxation processes at 250 K (IV' peak), 275 K (IV), 300 K (III), 400 K (II) and 440 K (I). This behavior is explained on the basis of the disaccommodation of vacancy-doped magnetite and another similar tetravalent substitution, as the previously analyzed Ti-doped magnetite

  4. Hazardous Solvent Substitution Data System tutorial

    International Nuclear Information System (INIS)

    Twitchell, K.E.; Skinner, N.L.

    1993-07-01

    This manual is the tutorial for the Hazardous Solvent Substitution Data System (HSSDS), an online, comprehensive system of information on alternatives to hazardous solvents and related subjects. The HSSDS data base contains product information, material safety data sheets, toxicity reports, usage reports, biodegradable data, product chemical element lists, and background information on solvents. HSSDS use TOPIC reg-sign to search for information based on a query defined by the user. TOPIC provides a full text retrieval of unstructured source documents. In this tutorial, a series of lessons is provided that guides the user through basic steps common to most queries performed with HSSDS. Instructions are provided for both window-based and character-based applications

  5. Substitution effects in magnetic and superconducting materials

    Directory of Open Access Journals (Sweden)

    Peña, O.

    1999-10-01

    Full Text Available Chemical substitutions at very low level have been proved to be a very effective tool to change important physical parameters in many kinds of materials. These modifications may be the result of, for instance, subtle variations of the position of the Fermi level with respect to the density of states, presence of additional electrons which may change the hole carrier concentration, steric effects which impose contraints in the crystallographic lattice, mixed-valence states resultating from the dismutation of chemical components, etc. We review herein three systems in which the substitution effects are at the origin of new physical states : the high-Tc superconductor bismuth cuprate of the 2212 family, the mixed-valence manganese perovskites representative of giant magneto-resistive compounds, and the Chevrel phase materials in which a structural transition may inhibit the superconducting state.

    Las substituciones químicas a un nivel muy pequeño se han probado como una importante herramienta para cambiar los parámetros físicos en una gran variedad de materiales. Estas modificaciones pueden ser el resultado de, por ejemplo, muy ligeras variaciones de la posición del nivel de Fermi con respecto a la densidad de estados, presencia de electrones adicionales que pueden cambiar la concentración de portadores tipo huecos, efectos estéricos que imponen restricciones en la red cristalográfica, estados de valencia mixtos resultantes de la dismutación de los componentes químicos, etc. Aquí se revisan tres sistemas donde los efectos de substitución son el origen de nuevos estados físicos: los superconductores de alta temperatura basados en cupratos de bismuto de la familia 2212, las perovskitas de manganeso de valencia mixta representantes de compuestos con magnetorresistencia gigante, y los materiales con fases de Chevrelt cuya transición estructural puede inhibir el estado superconductor.

  6. Substituted Pyrazinecarboxamides: Synthesis and Biological Evaluation

    Directory of Open Access Journals (Sweden)

    Katarina Kralova

    2006-03-01

    Full Text Available Condensation of the corresponding chlorides of some substituted pyrazine-2-carboxylic acids (pyrazine-2-carboxylic acid, 6-chloropyrazine-2-carboxylic acid, 5-tert-butylpyrazine-2-carboxylic acid or 5-tert-butyl-6-chloropyrazine-2-carboxylic acid withvarious ring-substituted aminothiazoles or anilines yielded a series of amides. Thesyntheses, analytical and spectroscopic data of thirty newly prepared compounds arepresented. Structure-activity relationships between the chemical structures and the anti-mycobacterial, antifungal and photosynthesis-inhibiting activity of the evaluatedcompounds are discussed. 3,5-Bromo-4-hydroxyphenyl derivatives of substitutedpyrazinecarboxylic acid, 16-18, have shown the highest activity against Mycobacteriumtuberculosis H37Rv (54-72% inhibition. The highest antifungal effect againstTrichophyton mentagrophytes, the most susceptible fungal strain tested, was found for5-tert-butyl-6-chloro-N-(4-methyl-1,3-thiazol-2-ylpyrazine-2-carboxamide (8, MIC =31.25 μmol·mL-1. The most active inhibitors of oxygen evolution rate in spinachMolecules 2006, 11 243 chloroplasts were the compounds 5-tert-butyl-6-chloro-N-(5-bromo-2-hydroxyphenyl- pyrazine-2-carboxamide (27, IC50 = 41.9 μmol·L-1 and 5-tert-butyl-6-chloro-N-(1,3- thiazol-2-yl-pyrazine-2-carboxamide (4, IC50 = 49.5 μmol·L-1.

  7. Polyphosphates substitution for zeolite to in detergents

    International Nuclear Information System (INIS)

    Restrepo V, Gloria M.; Ocampo G, Aquiles; Saldarriaga M, Carlos

    1996-01-01

    The detergents, as well as the cleaning products, contain active ingredients that are good to increase their efficiency and some of them, as the sodium Tripoli-phosphate (TPF), they have turned out to be noxious for the environment. The zeolites use in the formulation of detergents has grown substantially since they fulfill the same function of the TPF and they have been recommended ecologically as substitutes from these when not being polluting. The objective of this work is to obtain a zeolite with appropriate characteristics for its use in the formulation of detergents, reproducing those of the zeolites used industrially. The zeolite synthesis is studied 4A starting from hydro-gels of different composition, varying the operation conditions and using two raw materials: (sodium meta-silicate, commercial degree and metallic aluminum) and clay type kaolin like silica source and aluminum It is looked for to get a product of beveled cubic morphology, or spherical, with glass size between 1 and 3 microns and that it possesses good capacity of conical exchange. Since the capacity and speed of ionic exchange is influenced by the particle size, time of contact and temperature, experimentation conditions settle down to measure the exchange of ions calcium and magnesium in watery solutions that they simulate the real situation of a laundry process in the country. This way the ability of the zeolite 4A obtained to diminish the concentration of these ions in the laundry waters is evaluated and its possibilities like component in the formulation of detergents non-phosphatates. Of the synthesized zeolites, the best in agreement is chosen with chemical properties as ionic and physical exchange capacity as crystalline, particle size and color, to prepare a detergent in which the polyphosphates is substituted partial and totally for the synthesized zeolite

  8. Spectroscopic Evidence for Covalent Binding of Sulfadiazine to Natural Soils via 1,4-nucleophilic addition (Michael Type Addition) studied by Spin Labeling ESR

    Science.gov (United States)

    Aleksandrova, Olga

    2015-04-01

    with different polarity. As shown by the spin labeling ESR experiment, molecules modeling SDZ were promptly bound to non-hydrolysable network of soil organic matter only via the aromatic amines that was accompanied by a prompt enlargement of humic particles binding aromatic amines, whereas binding of decomposition products of SDZ to humic acids of soil via the aliphatic amines was not observable. The ESR spectra obviously showed a single-phase process of covalent binding of the aromatic amines. Repeated washouts of labeled soil samples using distil water and ultrafiltration through the membrane of 5000 MWCO PES confirmed irreversible binding of the aromatic amines, and showed that via the aliphatic amines, binding of SDZ or decomposition products of SDZ to soil might also occur but reversibly and only to small soil molecules, which don't enter into the composition of non-hydrolysable part of soil organic matter. SL ESR experiments of different soils at the presence of Laccase highlighted that covalent binding of the aromatic amines to humic particles occurred in the specific hydrophobic areas of soil found as depleted in oxygen. All measured data evidenced that first, SDZ might be decomposed that allowed for measuring the same change of a paramagnetic signal of soil organic matter influenced by both aromatic and aliphatic amines as in the experiment of the interaction of soil with SDZ. Second, a decomposition product of SDZ with the aromatic amine might be bound to non-hydrolysable parts of soil organic matter under specific anaerobic conditions only via 1,4 - nucleophilic addition, Michael-type addition. Gulkowska, A., Thalmann, B., D., Hollender, J., & Krauss, M. (2014). Chemosphere, 107, 366 - 372. Müller, T., Rosendahl, I., Focks, A., Siemens, J., Klasmeier, J., & Matthies. (2013). Environmental Pollution, 172,180 - 185. Nowak, K.M., Miltner, A., Gehre, M., Schaeffer, A., & Kaestner, M. (2011). Environmental Science & Technology 45, 999 - 1006. Weber, E.J., Spidle

  9. A theoretical quantum study on the distribution of electrophilic and nucleophilic active sites on Cu(100) surfaces modeled as finite clusters; Un estudio teorico cuantico sobre la distribucion de sitios activos electrofilicos y nucleofilicos sobre superficies de Cu(100) modeladas como cumulos finitos

    Energy Technology Data Exchange (ETDEWEB)

    Rios R, C.H.; Romero R, M. [Universidad Autonoma Metropolitana-Azcapotzalco, Departamento de Materiales, Av. San Pablo 180, Col. Reynosa Tamaulipas, 02200 Mexico D.F. (Mexico); Ponce R, A.; Mendoza H, L.H. [Universidad Autonoma del Estado de Hidalgo, Centro de Investigaciones Quimicas, Carretera Pachuca-Tulancingo km. 4.5, 42181 Pachuca, Hidalgo (Mexico)]. e-mail: clara_hrr@yahoo.es

    2008-07-01

    In this work, it is shown a theoretical quantum study of the active sites distribution on a monocrystalline surface of Cu(100). The copper surface was modeled as finite clusters of 14, 23, 38 and 53 atoms. We performed Hartree-Fock and Density Functional Theory (B3LYP) ab initio calculations employing the pseudopotentials of Hay and Wadt (LANLlMB y LANL2DZ). From calculations, we found a work function value of 4.1 eV. The mapping of the HOMO and LUMO in the frozen core approximation, allowed us finding the electrophilic and nucleophilic active sites distribution, respectively. The results indicated that electrophilic sites on the Cu(100) surface were located on hollow position and its numerical density was 8.6 x 10{sup 16} sites cm{sup -2}. From the nucleophilic local softness study, it was found that the nucleophilic sites were formed by a group of atoms and it had a numerical density of 2.4x 10{sup 16} sitescm{sup -2} . Last results indicated that adsorptions with 2 x 2 and 3 x 3 distributions can be favored onto a Cu(100) surface for the electrophilic and nucleophilic cases, respectively. (Author)

  10. Reatividade de ciclopropenonas frente a nucleófilos e sua correlação com potenciais de redução em meio aprótico Reactivity of cyclopropenones towards nucleophiles and correlation with reduction potentials in aprotic medium

    Directory of Open Access Journals (Sweden)

    Silvio Cunha

    2008-01-01

    Full Text Available In this work we studied the reactivity of isopropylphenylcyclopropenone towards some nitrogen nucleophiles whose reactions with methylphenylcyclopropenone and diphenylcyclopropenone were previously studied. The electrochemical behavior of these cyclopropenones was evaluated for the first time, and a correlation between electrochemical parameters and reactivity of this class of compounds was done.

  11. 49 CFR 383.77 - Substitute for driving skills tests.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Substitute for driving skills tests. 383.77... Substitute for driving skills tests. At the discretion of a State, the driving skill test as specified in... acceptable skills test, or an applicant's driving record in combination with certain driving experience. The...

  12. Substitute equations for index reduction and discontinuity handling

    NARCIS (Netherlands)

    Fabian, G.; Beek, van D.A.; Rooda, J.E.

    2000-01-01

    Several techniques exist for index reduction and consistent initialization of higher index DAEs. Many such techniques change the original set of equations by differentiation, substitution, and/or introduction of new variables. This paper introduces substitute equations as a new language element. By

  13. Control of Chemical Risks by Substitution of Harmful Substances

    DEFF Research Database (Denmark)

    Jacobsen, Thomas

    1997-01-01

    Substitution of volatile, organic solvents with non-volatile, low-toxic esters of fatty acids for cleaning purposes in offset printing has successfully been implemented in several European countries. Similar substitutions in other industrial cleaning processes seem possible, especially regarding...

  14. Mass spectrometric investigation of vinyl-substituted organic boron compounds

    International Nuclear Information System (INIS)

    Tarielashvili, V.O.; Ordzhonikidze, K.G.; Parulava, L.P.; Vakhaniya, G.V.

    1992-01-01

    Mass spectrometric investigation of vinyl-substituted organic compounds was conducted. Ionization was performed by electron shock. Possibility of determining boron isotope content is all analyzed organic boron vinyl-substituted compounds by direct method is shown. This simplifies sufficiently and lowers the price of analysis, improves its accuracy and rapidity

  15. Design, Synthesis and Insecticidal Activities of Novel Phenyl Substituted Isoxazolecarboxamides

    Institute of Scientific and Technical Information of China (English)

    LIU Peng-fei; ZHANG Ji-feng; YAN Tao; XIONG Li-xia; LI Zheng-ming

    2012-01-01

    Thirteen novel phenyl substituted isoxazolecarboxamides were synthesized,and their structures were characterized by 1H NMR,elementary analysis and high-resolution mass spectrometry(HRMS) techniques.Their evaluated insecticidal activities against oriental armyworm(Mythimna separata) indicate that the phcnyl substituted isoxazolecarboxamides exhibited moderate insecticidal activities,among which compounds 9c and 9k showed comparatively higher activities.

  16. Sublattice imbalance of substitutionally doped nitrogen in graphene

    DEFF Research Database (Denmark)

    Lawlor, James A.; Gorman, Paul D.; Power, Stephen

    2014-01-01

    Motivated by the recently observed sublattice asymmetry of substitutional nitrogen impurities in CVD grown graphene, we show, in a mathematically transparent manner, that oscillations in the local density of states driven by the presence of substitutional impurities are responsible for breaking......, but should be present in other impurities. (C) 2014 Elsevier Ltd. All rights reserved....

  17. Maximum parsimony, substitution model, and probability phylogenetic trees.

    Science.gov (United States)

    Weng, J F; Thomas, D A; Mareels, I

    2011-01-01

    The problem of inferring phylogenies (phylogenetic trees) is one of the main problems in computational biology. There are three main methods for inferring phylogenies-Maximum Parsimony (MP), Distance Matrix (DM) and Maximum Likelihood (ML), of which the MP method is the most well-studied and popular method. In the MP method the optimization criterion is the number of substitutions of the nucleotides computed by the differences in the investigated nucleotide sequences. However, the MP method is often criticized as it only counts the substitutions observable at the current time and all the unobservable substitutions that really occur in the evolutionary history are omitted. In order to take into account the unobservable substitutions, some substitution models have been established and they are now widely used in the DM and ML methods but these substitution models cannot be used within the classical MP method. Recently the authors proposed a probability representation model for phylogenetic trees and the reconstructed trees in this model are called probability phylogenetic trees. One of the advantages of the probability representation model is that it can include a substitution model to infer phylogenetic trees based on the MP principle. In this paper we explain how to use a substitution model in the reconstruction of probability phylogenetic trees and show the advantage of this approach with examples.

  18. Effect of Honey as Partial Sugar Substitute on Pasting Properties ...

    African Journals Online (AJOL)

    The effect of partial substitution of sugar with liquid honey on the pasting properties of cooked dough made from cassava-wheat composite (10:90) flour as well as the sensory preference and shelf stability of its bread was investigated. Sucrose (S) in the bread recipe formulation was substituted with honey (H) at levels 0, 10, ...

  19. Thermal stability of substitutional ag in CdTe

    NARCIS (Netherlands)

    Jahn, SG; Hofsass, H; Restle, M; Ronning, C; Quintel, H; BharuthRam, K; Wahl, U

    The thermal stability of substitutional Ag in CdTe was deduced from lattice location measurements at different temperatures. Substitutional Ag probe atoms were generated via transmutation doping from radioactive Cd isotopes. The lattice sites of Ag isotopes were determined by measuring the

  20. Influence of higher sodium substitutions on magnetic entropy ...

    Indian Academy of Sciences (India)

    The change in entropy also decreases with increase in substitution of sodium. A notable change ... of substituting elements for A and B ions, valence states of. Mn and the oxygen ... applied external magnetic field of 7 T.17 Sodium substitu- ..... Bohigas X, Tejada J, Del Barco E, Zhang X X and Sales M. 1998 Appl. Phys. Lett.

  1. 21 CFR 184.1259 - Cocoa butter substitute.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Cocoa butter substitute. 184.1259 Section 184.1259... FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS § 184.1259 Cocoa butter substitute. (a) The common or...

  2. 76 FR 8666 - Substitution in Case of Death of Claimant

    Science.gov (United States)

    2011-02-15

    ... DEPARTMENT OF VETERANS AFFAIRS 38 CFR Parts 3, 14, 20 RIN 2900-AN91 Substitution in Case of Death... Veterans Affairs (VA) proposes to amend its regulations concerning adjudication of claims, representation..., not later than one year after the death of the claimant, request to be substituted for the claimant...

  3. Labour migration and substitution (updated) : Second, revised version

    NARCIS (Netherlands)

    Cremers, Jan

    2017-01-01

    This (revised) paper compares the outcomes of several national and international studies on substitution as a consequence of migrants entering the labour market. Substitution appears if finding a job by one person results in the job loss (or non-obtaining of a job) of another person. The recruitment

  4. Substitution as a Device of Grammatical Cohesion in English Contexts

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Hasannejad

    2012-05-01

    Full Text Available The present study set out to investigate the effect of teaching substitution as a kind of grammatical cohesion on the true identification of confusing substitution elements with cohesive or non-cohesive roles in different contexts and also the production of modal, reporting and conditional contexts through clausal substitution acquaintance. To this end, the following procedures were taken. First 120 male and female EFL students were selected from Iranshahr Azad University. Having administered the language proficiency test, researchers selected 80 students as intermediate subjects according to their TOEFL band scores. First, pretests of cohesion identification (substitution and production of modal, reporting and conditional environments were administered to both control and experimental groups. Then, the experimental group was exposed to the teaching of the above-said above-mentioned cohesive device. Finally, post-tests of substitution elements’ identification and modal, reporting and conditional contexts’ production through clausal substitution familiarity were administered. The results showed that cohesive device treatment helped students on the true identification of substitution elements. Another finding proved that EFL students might have no difficulty in learning certain rules or classification of rules and application of their clausal substitution knowledge in creating modal, reporting and conditional contexts. Our findings can have implications for the field of language learning and teaching.

  5. 40 CFR 721.562 - Substituted alkylamine salt.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Substituted alkylamine salt. 721.562 Section 721.562 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.562 Substituted alkylamine salt...

  6. 40 CFR 721.5278 - Substituted naphthalenesulfonic acid, alkali salt.

    Science.gov (United States)

    2010-07-01

    ..., alkali salt. 721.5278 Section 721.5278 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.5278 Substituted naphthalenesulfonic acid, alkali salt. (a) Chemical... as a substituted naphthalenesulfonic acid, alkali salt (PMN P-95-85) is subject to reporting under...

  7. 40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

    Science.gov (United States)

    2010-07-01

    ..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical... as substituted halogenated pyridinols, alkali salts (PMNs P-88-1271 and P-88-1272) are subject to...

  8. Cation substitution induced blue-shift of optical band gap

    Indian Academy of Sciences (India)

    Cation substitution induced blue-shift of optical band gap in nanocrystalline Zn ( 1 − x ) Ca x O thin films deposited by sol–gel dip coating technique ... thin films giving 13.03% enhancement in theenergy gap value due to the electronic perturbation caused by cation substitution as well as deterioration in crystallinity.

  9. MOLECULAR THERMODYNAMICS IN THE DESIGN OF SUBSTITUTE SOLVENTS

    Science.gov (United States)

    The use of physical properties and fluid behavior from molecular thermodynamics can lead to better decision making in the design of substitute solvents and can greatly reduce the expense and time required to find substitutes compared to designing solvents by experiment. this pape...

  10. Antimony substitution in SmFeAsO

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Daniel; Braun, Hans F. [Universitaet Bayreuth (Germany)

    2015-07-01

    In the iron based compounds structural and magnetic phase transitions can be suppressed by applying external hydrostatic pressure and superconductivity emerges. Beside hydrostatic pressure, it is possible to apply chemical pressure by the substitution of atoms in the compounds with smaller ones. Such a substitution was successful for example in LaFeAs{sub 1-x}P{sub x}O, where the parent compound shows a structural and a spin-density-wave transition and the P doped samples become superconducting. We are interested in the opposite way and substitute the As by the bigger Sb. In literature, the substitution in the La-1111 compounds was possible up to a substitution level of 40 %. With Sm, instead of La, we used a smaller rare-earth metal. We present the results obtained on polycrystalline samples characterized by Xray powder diffraction and resistivity measurements.

  11. REACH-related substitution within the Danish printing industry

    DEFF Research Database (Denmark)

    Larsen, Henrik Fred; Bøg, Carsten; Markussen, Helene

    are running a substitution project. A major part of the work has been mapping the presence of chemicals which are potential candidates for substitution (e.g. PBT, CMR, vPvB, EDS) within the Danish printing industry. The mapping comprises a combination of a literature study and an investigation of the actual......The accomplishment of the EU REACH regulation will most probably promote substitution within sectors handling a lot of different chemicals like the printing industry. With the aim of being at the cutting edge of this development the Danish EPA together with the Danish printing industry and IPU...... fulfil one or more of the criteria (e.g. CMR, EDS) for the REACH Annex XIV candidate list (authorisation). The paper presents the results of the mapping of chemical candidates and the first results of the actual substitutions. Keywords: REACH, chemicals, substitution, printing industry....

  12. A Group Action Method for Construction of Strong Substitution Box

    Science.gov (United States)

    Jamal, Sajjad Shaukat; Shah, Tariq; Attaullah, Atta

    2017-06-01

    In this paper, the method to develop cryptographically strong substitution box is presented which can be used in multimedia security and data hiding techniques. The algorithm of construction depends on the action of a projective general linear group over the set of units of the finite commutative ring. The strength of substitution box and ability to create confusion is assessed with different available analyses. Moreover, the ability of resistance against malicious attacks is also evaluated. The substitution box is examined by bit independent criterion, strict avalanche criterion, nonlinearity test, linear approximation probability test and differential approximation probability test. This substitution box is equated with well-recognized substitution boxes such as AES, Gray, APA, S8, prime of residue, Xyi and Skipjack. The comparison shows encouraging results about the strength of the proposed box. The majority logic criterion is also calculated to analyze the strength and its practical implementation.

  13. Potential radiosensitizing agents. 5. 2-Substituted benzimidazole derivatives

    International Nuclear Information System (INIS)

    Gupta, R.P.; Larroquette, C.A.; Agrawal, K.C.

    1982-01-01

    A series of 2-substituted benzimidazoles and their derivatives have been synthesized and tested for their ability to selectively sensitize hypoxic Chinese hamster cells (V-79) toward the lethal effect of ionizing radiation. These compounds were prepared by reacting the 2-substituted benzimidazoles with 1,2-epoxy-3-methoxypropane in the presence of potassium carbonate. Reaction of the 2-nitro and 2-methylfonyl analogue with the epoxide also yielded a cyclized material, which was confirmed to be a benzimidazo[2,1-b]oxazole. In an attempt to increase the electron affinity, 5- or 6-nitro-2-substituted-benzimidazoles were also synthesized and then reacted with the epoxide to yield the corresponding 1-substituted derivatives. The results of the biological tests for the radiosensitizing activity of these agents against Chinese hamster cells (V-79) in culture indicated that the 2-nitro-substituted analogues were the most effective sensitizers in this series

  14. Substituted amylose matrices for oral drug delivery

    International Nuclear Information System (INIS)

    Moghadam, S H; Wang, H W; El-Leithy, E Saddar; Chebli, C; Cartilier, L

    2007-01-01

    High amylose corn starch was used to obtain substituted amylose (SA) polymers by chemically modifying hydroxyl groups by an etherification process using 1,2-epoxypropanol. Tablets for drug-controlled release were prepared by direct compression and their release properties assessed by an in vitro dissolution test (USP XXIII no 2). The polymer swelling was characterized by measuring gravimetrically the water uptake ability of polymer tablets. SA hydrophilic matrix tablets present sequentially a burst effect, typical of hydrophilic matrices, and a near constant release, typical of reservoir systems. After the burst effect, surface pores disappear progressively by molecular association of amylose chains; this allows the creation of a polymer layer acting as a diffusion barrier and explains the peculiar behaviour of SA polymers. Several formulation parameters such as compression force, drug loading, tablet weight and insoluble diluent concentration were investigated. On the other hand, tablet thickness, scanning electron microscope analysis and mercury intrusion porosimetry showed that the high crushing strength values observed for SA tablets were due to an unusual melting process occurring during tabletting although the tablet external layer went only through densification, deformation and partial melting. In contrast, HPMC tablets did not show any traces of a melting process

  15. Development of a piezoelectric bone substitute material

    International Nuclear Information System (INIS)

    Al-Bader, Yousef A.

    2000-01-01

    The thesis deals with the preparation and testing of ceramic compositions to be used as bone substitute. The proposed composition consisted of calcium enriched calcium phosphate, kaolin and barium titanate in different ratios. The homogeneous powder mixture was dry pressed at different pressures and fired at temperatures up to 1350 degC for different soaking times. The physical properties of the fired compacts that were tested are bulk density and porosity. These were determined as function of pressing pressure, firing temperature and soaking time for different compositions. The mechanical properties investigated were the ultimate compressive strength and Young's modulus, which were determined for different compositions and forming pressures. The electrical properties investigated were D.C. characteristics (resistivity) and A.C. characteristics (A.C. resistivity, dielectric constant, dielectric loss and loss tangent). The piezoelectric behaviour of the fired compacts was investigated and the piezoelectric coefficient (d) in the axial direction was obtained as a function of the percent barium titanate added. The development of piezoelectricity when barium titanate is added was interpreted, using XRD, as due to the formation of barium titanate silicate. Compositions determined as having properties comparable to those of natural bone, were tested for in vitro solubility in pure water and saline solution. The results obtained showed that the selected composition (containing 15% kaolin, 10% barium titanate, pressed at 35 MPa and fired at 1350 degC for two hours) has properties comparable to those of dry bone and a reasonable in vitro solubility. (author)

  16. Substitution of photomultiplier tubes by photodiodes

    International Nuclear Information System (INIS)

    Teixeira, D.L.

    1990-04-01

    The application of Si semiconductors, either of the conventional or the avalanche type, as light amplifiers in radiation detection, has been studied aiming the substitution of photomultiplier (PM) tubes by photodiodes. The objective of this work is to compare the response of photodiodes and PM tubes when coupled to scintillation crystals. A Hamamatsu Si photodiode, model S 1337-66 B Q, was coupled to a Harshaw NaI (TI) scintillation crystal of window diameter equal to 25,4 mm. Its performance was evaluated by specially designed associated electronics, compatible with the photodiode characteristics. X-ray beams from 30 to 111 KeV were used to determine the response and the repeatability of the scintillator-photodiode and the scintillator-PM tube systems. The repeatability was found to be within 0,27% for the photodiode and 0,57% for the PM tube. This work confirmed that photodiodes can be used as light amplifiers, provided their characteristics, such as light spectrum response, are considered. It also shows that further studies are necessary in order to identify the applications in radiation detection where PM tubes might be replaced by photodiodes. (author)

  17. New substitution models for rooting phylogenetic trees.

    Science.gov (United States)

    Williams, Tom A; Heaps, Sarah E; Cherlin, Svetlana; Nye, Tom M W; Boys, Richard J; Embley, T Martin

    2015-09-26

    The root of a phylogenetic tree is fundamental to its biological interpretation, but standard substitution models do not provide any information on its position. Here, we describe two recently developed models that relax the usual assumptions of stationarity and reversibility, thereby facilitating root inference without the need for an outgroup. We compare the performance of these models on a classic test case for phylogenetic methods, before considering two highly topical questions in evolutionary biology: the deep structure of the tree of life and the root of the archaeal radiation. We show that all three alignments contain meaningful rooting information that can be harnessed by these new models, thus complementing and extending previous work based on outgroup rooting. In particular, our analyses exclude the root of the tree of life from the eukaryotes or Archaea, placing it on the bacterial stem or within the Bacteria. They also exclude the root of the archaeal radiation from several major clades, consistent with analyses using other rooting methods. Overall, our results demonstrate the utility of non-reversible and non-stationary models for rooting phylogenetic trees, and identify areas where further progress can be made. © 2015 The Authors.

  18. Some comments on the substituted judgement standard.

    Science.gov (United States)

    Egonsson, Dan

    2010-02-01

    On a traditional interpretation of the substituted judgement standard (SJS) a person who makes treatment decisions on behalf of a non-competent patient (e.g. concerning euthanasia) ought to decide as the patient would have decided had she been competent. I propose an alternative interpretation of SJS in which the surrogate is required to infer what the patient actually thought about these end-of-life decisions. In clarifying SJS it is also important to differentiate the patient's consent and preference. If SJS is part of an autonomy ideal of the sort found in Kantian ethics, consent seems more important than preference. From a utilitarian perspective a preference-based reading of SJS seems natural. I argue that the justification of SJS within a utilitarian framework will boil down to the question whether a non-competent patient can be said to have any surviving preferences. If we give a virtue-ethical justification of SJS the relative importance of consent and preferences depends on which virtue one stresses--respect or care. I argue that SJS might be an independent normative method for extending the patient's autonomy, both from a Kantian and a virtue ethical perspective.

  19. Hazardous Solvent Substitution Data System reference manual

    International Nuclear Information System (INIS)

    Branham-Haar, K.A.; Twitchell, K.E.

    1993-07-01

    Concern for the environment, in addition to Federal regulation, mandate the replacement of hazardous solvents with safer cleaning agents. Manufacturers are working to produce these replacement solvents. As these products are developed, potential users need to be informed of their availability. To promote the use of these new products instead of traditional solvents, the Idaho National Engineering Laboratory (INEL) has developed the Hazardous Solvent Substitution Data System (HSSDS). The HSSDS provides a comprehensive system of information on alternatives to hazardous solvents and related subjects, and it makes that information available to solvent users, industrial hygienists, and process engineers. The HSSDS uses TOPIC reg-sign, a text retrieval system produced by Verity, Inc., to allow a user to search for information on a particular subject. TOPIC reg-sign produces a listing of the retrieved documents and allows the use to examine the documents individually and to use the information contained in them. This reference manual does not replace the comprehensive TOPIC reg-sign user documentation (available from Verity, Inc.), or the HSSDS Tutorial (available from the INEL). The purpose of this reference manual is to provide enough instruction on TOPIC reg-sign so the user may begin accessing the data contained in the HSSDS

  20. 40 CFR Appendix H to Subpart G of... - Substitutes Subject to Use Restrictions and Unacceptable Substitutes, Effective May 28, 1999

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 17 2010-07-01 2010-07-01 false Substitutes Subject to Use Restrictions and Unacceptable Substitutes, Effective May 28, 1999 H Appendix H to Subpart G of Part 82... STRATOSPHERIC OZONE Significant New Alternatives Policy Program Pt. 82, Subpt. G, App. H Appendix H to Subpart G...

  1. Radiation chemistry of alternative fuel oxygenates - substituted ethers

    International Nuclear Information System (INIS)

    Mezyk, S. P.; Cooper, W. J.; Bartels, D. M.; Tobien, T.; O'Shea, K. E.

    1999-01-01

    The electron beam process, an advanced oxidation and reduction technology, is based in the field of radiation chemistry. Fundamental to the development of treatment processes is an understanding of the underlying chemistry. The authors have previously evaluated the bimolecular rate constants for the reactions of methyl tert-butyl ether (MTBE) and with this study have extended their studies to include ethyl tert-butyl ether (ETBE), di-isopropyl ether (DIPE) and tert-amyl methyl ether (TAME) with the hydroxyl radical, hydrogen atom and solvated electron using pulse radiolysis. For all of the oxygenates the reaction with the hydroxyl radical appears to be of primary interest in the destruction of the compounds in water. The rates with the solvated electron are limiting values as the rates appear to be relatively low. The hydrogen atom rate constants are relatively low, coupled with the low yield in radiolysis, they concluded that these are of little significance in the destruction of the alternative fuel oxygenates (and MTBE)

  2. Nonsynonymous substitution in abalone sperm fertilization genes exceeds substitution in introns and mitochondrial DNA

    Science.gov (United States)

    Metz, Edward C.; Robles-Sikisaka, Refugio; Vacquier, Victor D.

    1998-01-01

    Strong positive Darwinian selection acts on two sperm fertilization proteins, lysin and 18-kDa protein, from abalone (Haliotis). To understand the phylogenetic context for this dramatic molecular evolution, we obtained sequences of mitochondrial cytochrome c oxidase subunit I (mtCOI), and genomic sequences of lysin, 18-kDa, and a G protein subunit. Based on mtDNA differentiation, four north Pacific abalone species diverged within the past 2 million years (Myr), and remaining north Pacific species diverged over a period of 4–20 Myr. Between-species nonsynonymous differences in lysin and 18-kDa exons exceed nucleotide differences in introns by 3.5- to 24-fold. Remarkably, in some comparisons nonsynonymous substitutions in lysin and 18-kDa genes exceed synonymous substitutions in mtCOI. Lysin and 18-kDa intron/exon segments were sequenced from multiple red abalone individuals collected over a 1,200-km range. Only two nucleotide changes and two sites of slippage variation were detected in a total of >29,000 nucleotides surveyed. However, polymorphism in mtCOI and a G protein intron was found in this species. This finding suggests that positive selection swept one lysin allele and one 18-kDa allele to fixation. Similarities between mtCOI and lysin gene trees indicate that rapid adaptive evolution of lysin has occurred consistently through the history of the group. Comparisons with mtCOI molecular clock calibrations suggest that nonsynonymous substitutions accumulate 2–50 times faster in lysin and 18-kDa genes than in rapidly evolving mammalian genes. PMID:9724763

  3. The role of biomass in US industrial interfuel substitution

    International Nuclear Information System (INIS)

    Jones, Clifton T.

    2014-01-01

    The role of biomass in US industrial interfuel substitution in the industrial sector has typically been analyzed using data for the four traditional fuels of coal, oil, electricity and natural gas. However, the use of biomass as an industrial fuel in the US has grown, and now exceeds that of coal. Using data from 1960 to 2011, interfuel substitution in the US industrial sector is modeled with a dynamic linear logit model which includes biomass alongside the other four traditional fuels. Adding biomass to the model reduces somewhat the estimated own-price and cross-price elasticities for the other four fuels, while revealing that biomass and natural gas are substitute fuels. This implies that previous studies excluding biomass may have overestimated the potential for interfuel substitution, giving policy makers an inaccurate impression of the ability of carbon taxes or other environmental regulation to reduce greenhouse gas (GHG) emissions. - Highlights: • Biomass usage by the US industrial sector now exceeds coal usage. • Previous interfuel substitution studies have not included biomass as a fuel. • Linear logit model is used to examine role of biomass in interfuel substitution. • Including biomass in the model lowers estimated price elasticities for traditional fuels. • Biomass is found to be a substitute for natural gas for industrial users

  4. Enhanced osteoconductivity of sodium-substituted hydroxyapatite by system instability.

    Science.gov (United States)

    Sang Cho, Jung; Um, Seung-Hoon; Su Yoo, Dong; Chung, Yong-Chae; Hye Chung, Shin; Lee, Jeong-Cheol; Rhee, Sang-Hoon

    2014-07-01

    The effect of substituting sodium for calcium on enhanced osteoconductivity of hydroxyapatite was newly investigated. Sodium-substituted hydroxyapatite was synthesized by reacting calcium hydroxide and phosphoric acid with sodium nitrate followed by sintering. As a control, pure hydroxyapatite was prepared under identical conditions, but without the addition of sodium nitrate. Substitution of calcium with sodium in hydroxyapatite produced the structural vacancies for carbonate ion from phosphate site and hydrogen ion from hydroxide site of hydroxyapatite after sintering. The total system energy of sodium-substituted hydroxyapatite with structural defects calculated by ab initio methods based on quantum mechanics was much higher than that of hydroxyapatite, suggesting that the sodium-substituted hydroxyapatite was energetically less stable compared with hydroxyapatite. Indeed, sodium-substituted hydroxyapatite exhibited higher dissolution behavior of constituent elements of hydroxyapatite in simulated body fluid (SBF) and Tris-buffered deionized water compared with hydroxyapatite, which directly affected low-crystalline hydroxyl-carbonate apatite forming capacity by increasing the degree of apatite supersaturation in SBF. Actually, sodium-substituted hydroxyapatite exhibited markedly improved low-crystalline hydroxyl-carbonate apatite forming capacity in SBF and noticeably higher osteoconductivity 4 weeks after implantation in calvarial defects of New Zealand white rabbits compared with hydroxyapatite. In addition, there were no statistically significant differences between hydroxyapatite and sodium-substituted hydroxyapatite on cytotoxicity as determined by BCA assay. Taken together, these results indicate that sodium-substituted hydroxyapatite with structural defects has promising potential for use as a bone grafting material due to its enhanced osteoconductivity compared with hydroxyapatite. © 2013 Wiley Periodicals, Inc.

  5. Substitute natural gas from biomass gasification

    Energy Technology Data Exchange (ETDEWEB)

    Tunaa, Per (Lund Inst. of Technology, Lund (SE))

    2008-03-15

    Biomass is by many considered as the only alternative to phase-out the usage of fossil fuels such as natural gas and oil especially for the transportation sector where alternative solutions, such as hydrogen fuel cells and batteries, are not yet fully developed. Thermal gasification or other methods such as pyrolysis of the biomass must be applied in order to produce an intermediate product suitable for further upgrading to either gaseous or liquid products. This thesis will evaluate the possibilities of producing, substitute natural gas, (SNG) from biomass gasification by using computer simulation. Three different gasification techniques were evaluated; entrained-flow, fluidized-bed and indirect gasification coupled with two different desulphurisation systems and two methanation processes. The desulphurisation systems were a zinc oxide bed and a Rectisol wash system. Methanation were performed by a series of adiabatic reactors with gas recycling and by an isothermal reactor. The impact on SNG efficiency from system pressure, isothermal methanation temperature and PSA methane recovery were evaluated as well. The results show that the fluidized-bed and the indirect gasifier have the highest SNG efficiency. Furthermore there are little to no difference between the methanation processes and small differences for the gas cleanup systems. SNG efficiencies in excess of 50 % were possible for all gasifiers. SNG efficiency is defined as the energy in the SNG product divided by the total input to the system from biomass, drying and oxygen. Increasing system pressure has a negative impact on SNG efficiency as well as increasing operating costs due to increased power for compression. Isothermal methanation temperature has no significant impact on SNG efficiency. Recovering as much methane as possible in the PSA is the most important parameter. Recovering methane that has been dissolved in condensed process water increases the SNG efficiency by 2-10% depending on system.

  6. From incremental to fundamental substitution in chemical alternatives assessment

    DEFF Research Database (Denmark)

    Fantke, Peter; Weber, Roland; Scheringer, Martin

    2015-01-01

    to similarity in chemical structures and, hence, similar hazard profiles between phase-out and substitute chemicals, leading to a rather incremental than fundamental substitution. A hampered phase-out process, the lack of implementing Green Chemistry principles in chemicals design, and lack of Sustainable...... an integrated approach of all stakeholders involved toward more fundamental and function-based substitution by greener and more sustainable alternatives. Our recommendations finally constitute a starting point for identifying further research needs and for improving current alternatives assessment practice....

  7. Chitosan Dermal Substitute and Chitosan Skin Substitute Contribute to Accelerated Full-Thickness Wound Healing in Irradiated Rats

    Directory of Open Access Journals (Sweden)

    Abu Bakar Mohd Hilmi

    2013-01-01

    Full Text Available Wounds with full-thickness skin loss are commonly managed by skin grafting. In the absence of a graft, reepithelialization is imperfect and leads to increased scar formation. Biomaterials can alter wound healing so that it produces more regenerative tissue and fewer scars. This current study use the new chitosan based biomaterial in full-thickness wound with impaired healing on rat model. Wounds were evaluated after being treated with a chitosan dermal substitute, a chitosan skin substitute, or duoderm CGF. Wounds treated with the chitosan skin substitute showed the most re-epithelialization (33.2 ± 2.8%, longest epithelial tongue (1.62 ± 0.13 mm, and shortest migratory tongue distance (7.11 ± 0.25 mm. The scar size of wounds treated with the chitosan dermal substitute (0.13 ± 0.02 cm and chitosan skin substitute (0.16 ± 0.05 cm were significantly decreased (P<0.05 compared with duoderm (0.45 ± 0.11 cm. Human leukocyte antigen (HLA expression on days 7, 14, and 21 revealed the presence of human hair follicle stem cells and fibroblasts that were incorporated into and surviving in the irradiated wound. We have proven that a chitosan dermal substitute and chitosan skin substitute are suitable for wound healing in full-thickness wounds that are impaired due to radiation.

  8. Performance of chicken broilers fed with diets substituted with ...

    African Journals Online (AJOL)

    Performance of chicken broilers fed with diets substituted with mulberry leaf powder. Carlina Freddie Simol, Andrew Alek Tuen, Humrawali Hazid Ahmad Khan, John Keen Chubo, Patricia Jie Hung King, Kian Huat Ong ...

  9. Modified broken rice starch as fat substitute in sausages

    Directory of Open Access Journals (Sweden)

    Valéria Maria Limberger

    2011-09-01

    Full Text Available The demand for low-fat beef products has led the food industry to use fat substitutes such as modified starch. About 14% of broken rice is generated during processing. Nevertheless, this by-product contains high levels of starch; being therefore, great raw material for fat substitution. This study evaluated the applicability of chemically and physically modified broken rice starch as fat substitute in sausages. Extruded and phosphorylated broken rice was used in low-fat sausage formulation. All low-fat sausages presented about 55% reduction in the fat content and around 28% reduction in the total caloric value. Fat replacement with phosphorylated and extruded broken rice starch increased the texture acceptability of low-fat sausages, when compared to low-fat sausages with no modified broken rice. Results suggest that modified broken rice can be used as fat substitute in sausage formulations, yielding lower caloric value products with acceptable sensory characteristics.

  10. Aligning protein sequence and analysing substitution pattern using ...

    Indian Academy of Sciences (India)

    Prakash

    Aligning protein sequences using a score matrix has became a routine but valuable method in modern biological ..... the amino acids according to their substitution behaviour ...... which may cause great change (e.g. prolonging the helix) in.

  11. Long term substitution treatment (maintenance treatment of opioid dependent persons

    Directory of Open Access Journals (Sweden)

    Wirl, Charlotte

    2007-03-01

    Full Text Available Health political background: Methadone substitution treatment in Germany is introduced in 1988 in the framework of a scientific pilot study in North Rhein Westphalia. Recent statistics show that by now a broad offer of substitution treatment exists. From 1 June 2002 to 31 December 2003 113,000 substitution treatments have been recorded as being started of which around 56,000 have been recorded as ongoing treatments by 1 December 2003. Scientific background: Substitution treatment (treatment of opioid-dependent persons using substitution substances is one part of addiction treatment. Its goals are harm reduction and the stabilisation of opioid dependent persons. Integration of opioid-dependent persons in a treatment-setting, reduction of consumption of psychoactive substances, reduction of risk behaviour (primarily related to infectious diseases, decrease of mortality and improvements concerning the social, psychic and physic situation are seen as a success of substitution treatment as maintenance therapy. Research questions: The aim of this HTA report is to investigate which indicators can be used to evaluate the effectiveness of substitution treatment. Based on these indicators an evaluation of the medical, social and economical benefit of substitution treatment - also in relation to abstinence oriented treatment - is carried out. Methods: A systematic literature search was performed in 31 international databases which yielded 2451 articles with publication date between 1995 and February 2005. Results: After a twofold selection process 32 publications were included for assessment and 276 publications were used as background literature. Despite serious restrictions due to selection bias and dropout in most studies focusing on substitution treatment, reduction of consumption of illegal opioids, reduction of risk behaviour, criminal behaviour, mortality and incidence of HIV can be seen as an empirically proven success of substitution treatment

  12. Computational Modeling of Degradation of Substituted Benzyltrimethyl Ammonium: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Long, H.; Pivovar, B. S.

    2014-09-01

    The degradation of cations on the alkaline exchange membranes is the major challenge for alkaline membrane fuel cells. In this paper, we investigated the degradation barriers by density functional theory for substituted benzyltrimethyl ammonium (BTMA+) cations, which is one of the most commonly used cations for alkaline exchange membranes. We found that substituted cations with electron-releasing substituent groups at meta-position of the benzyl ring could result in improved degradation barriers. However, after investigating more than thirty substituted BTMA+ cations with ten different substituent groups, the largest improvement of degradation barriers is only 1.6 kcal/mol. This implies that the lifetime of alkaline membrane fuel cells could increase from a few months to a few years by using substituted BTMA+ cations, an encouraging but still limited improvement for real-world applications.

  13. Gold-catalyzed oxidation of substituted phenols by hydrogen peroxide

    KAUST Repository

    Cheneviere, Yohan; Caps, Valerie; Tuel, Alain

    2010-01-01

    Gold nanoparticles deposited on inorganic supports are efficient catalysts for the oxidation of various substituted phenols (2,6-di-tert-butyl phenol and 2,3,6-trimethyl phenol) with aqueous hydrogen peroxide. By contrast to more conventional

  14. Macroporous synthetic hydroxyapatite bioceramics for bone substitute applications

    CSIR Research Space (South Africa)

    Thomas, ME

    1999-08-01

    Full Text Available An improved strategy is described for the manufacture of macroporous hydroxyapatite bioceramics for bone substitute applications. This is based on a modified fugitive phase technique, which allows production of relatively open, high-strength devices...

  15. A Web service substitution method based on service cluster nets

    Science.gov (United States)

    Du, YuYue; Gai, JunJing; Zhou, MengChu

    2017-11-01

    Service substitution is an important research topic in the fields of Web services and service-oriented computing. This work presents a novel method to analyse and substitute Web services. A new concept, called a Service Cluster Net Unit, is proposed based on Web service clusters. A service cluster is converted into a Service Cluster Net Unit. Then it is used to analyse whether the services in the cluster can satisfy some service requests. Meanwhile, the substitution methods of an atomic service and a composite service are proposed. The correctness of the proposed method is proved, and the effectiveness is shown and compared with the state-of-the-art method via an experiment. It can be readily applied to e-commerce service substitution to meet the business automation needs.

  16. Substitution possibilities and determinants of energy intensity for China

    International Nuclear Information System (INIS)

    Ma, Hengyun; Oxley, Les; Gibson, John

    2009-01-01

    This paper measures technological change, factor demand and inter-factor and inter-fuel substitutability measures for China. We use individual fuel price data and a two-stage approach to estimate total factor cost functions and fuel share equations. Both inter-factor and inter-fuel substitution elasticities are calculated and the change in energy intensity is decomposed into its driving forces. The results suggest that energy is substitutable for capital regionally and for labor nationally. Capital substitutes for energy more easily than labor does. Energy intensity changes vary by region but the major drivers seem to be 'budget effect' and the adoption of energy-intensive technologies, which might be embodied in high-level energy-using exports and sectors, capital investment and even old technique and equipment imports. Whether the trend in rising energy intensity continues will be significant for China and the rest of the world. (author)

  17. Industrialization in Sub-Saharan Africa and import substitution policy

    Directory of Open Access Journals (Sweden)

    Ana Paula F. Mendes

    2014-03-01

    Full Text Available This article aims to contribute to the understanding of the process of import substitution in Sub-Saharan Africa. The process of industrialization in Sub-Saharan Africa occurred in two phases: a first step, even very early during the colonial regime began around the 1920s and ended in the late forties; a second phase of industrialization began in the late fifties and gained momentum in the sixties, when import substitution was implemented more widely. Although these countries were the last to embark on the strategy of import substitution, they followed the same steps of Latin American countries, and as the structural domestic and external constraints were too strong, the failure of the policy of import substitution arrived early and the negative impact on these economies had a greater magnitude.

  18. Curvature and elasticity of substitution: what is the link?

    Czech Academy of Sciences Publication Activity Database

    Matveenko, Andrei; Matveenko, V.

    2014-01-01

    Roč. 10, č. 2 (2014), s. 7-20 ISSN 1800-5845 Grant - others:UK(CZ) GAUK 308214 Institutional support: PRVOUK-P23 Keywords : curvature * elasticity of substitution * production function Subject RIV: AH - Economics

  19. Substitution possibilities and determinants of energy intensity for China

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Hengyun [College of Economics and Management, Henan Agricultural University, 95 Wenhua Road, Zhengzhou 450002 (China); Department of Economics, University of Canterbury, Private bag 4800, Christchurch 8140 (New Zealand); Oxley, Les [Department of Economics, University of Canterbury, Private bag 4800, Christchurch 8140 (New Zealand); Gibson, John [Department of Economics, University of Waikato, Private Bag 3105, Hamilton (New Zealand)

    2009-05-15

    This paper measures technological change, factor demand and inter-factor and inter-fuel substitutability measures for China. We use individual fuel price data and a two-stage approach to estimate total factor cost functions and fuel share equations. Both inter-factor and inter-fuel substitution elasticities are calculated and the change in energy intensity is decomposed into its driving forces. The results suggest that energy is substitutable for capital regionally and for labor nationally. Capital substitutes for energy more easily than labor does. Energy intensity changes vary by region but the major drivers seem to be 'budget effect' and the adoption of energy-intensive technologies, which might be embodied in high-level energy-using exports and sectors, capital investment and even old technique and equipment imports. Whether the trend in rising energy intensity continues will be significant for China and the rest of the world. (author)

  20. Calculating stocking rates for game ranches: substitution ratios for ...

    African Journals Online (AJOL)

    Calculating stocking rates for game ranches: substitution ratios for use in the Mopani ... Reports on a study conducted to quantify the overlap in ungulate resource-use on a game ranch, and to demonstrate how ... AJOL African Journals Online.

  1. 1-Hydroxyethyl-2-Substituted Phenoxymethyl Benzimidazoles: Synthesis and Crystal Structures

    International Nuclear Information System (INIS)

    Wu, J.; Wang, Z.; Gu, H.; Chen, W.; Zhao, L.; Zhao, C.

    2016-01-01

    Five novel 1-hydroxyethyl-2-substituted phenoxymethyl benzimidazoles c1-c5 were successfully synthesized by a three-step route. Firstly, five substituted phenoxymethyl acids a1-a5 were prepared by the O-carboxymethylation reaction of the starting substituted phenols under microwave irradiation. Then, these compounds reacted with o-phenylendiamine to get the key intermediates 2-substituted phenoxymethyl benzimidazoles b1-b5. At last, the target compounds were synthesized by the N-hydroxyethylation reaction of b1-b5 with 2-chloroethyl alcohol through the solid-liquid phase transfer catalysis method, where tetrabutyl ammonium bromide (TBAB) was used as the catalyst. The structures of the target compounds were well characterized and verified by elemental analysis, MS, IR, 1H NMR, 13C NMR and single crystal X-ray diffraction analysis. (author)

  2. Loan collaterals and collateral substitutes in rural finance: a review ...

    African Journals Online (AJOL)

    Loan collaterals and collateral substitutes in rural finance: a review. ... have difficulties in obtaining loans from banks and other financial institutions because ... The limited availability of conventional collaterals in rural financial markets has led ...

  3. Associations between generic substitution and patient-related factors

    DEFF Research Database (Denmark)

    Østergaard Rathe, Jette

    Associations between generic substitution and patient-related factors Jette Østergaard Rathe1, Pia V. Larsen1, Morten Andersen2, Janus L. Thomsen3, Maja S. Paulsen1, Jens Søndergaard1 1. Research Unit of General Practice, Institute of Public Health, University of Southern Denmark 2. Centre...... for Pharmacoepidemiology, Karolinska Institutet, Department of Medicine Solna, Stockholm, Sweden 3. Danish Quality Unit of General Practice, Odense, Denmark Background Generic substitution means that chemically equivalent but less expensive drugs are dispensed in place of a brand name product. Although generic medicines...... by definition are bioequivalent to their brand name counterparts there are concerns about whether generic substitution is always accompanied by clinical equivalence in terms of effectiveness and that it may cause concerns and thereby causing some skepticism towards generic substitution. There is, however...

  4. Osseointegration of subperiosteal implants using bovine bone substitute and various membranes

    DEFF Research Database (Denmark)

    Aaboe, Merete; Schou, S.; Hjørting-Hansen, E.

    2000-01-01

    Osseointegration, subperiosteal implant, bone substitute, bovine bone, guided bone, regeneration, histology, rabbits......Osseointegration, subperiosteal implant, bone substitute, bovine bone, guided bone, regeneration, histology, rabbits...

  5. Protein substitute for children and adults with phenylketonuria.

    Science.gov (United States)

    Yi, Sarah H L; Singh, Rani H

    2015-02-27

    Phenylketonuria is an inherited metabolic disorder characterised by an absence or deficiency of the enzyme phenylalanine hydroxylase. The aim of treatment is to lower blood phenylalanine concentrations to the recommended therapeutic range to prevent developmental delay and support normal growth. Current treatment consists of a low-phenylalanine diet in combination with a protein substitute which is free from or low in phenylalanine. Guidance regarding the use, dosage, and distribution of dosage of the protein substitute over a 24-hour period is unclear, and there is variation in recommendations among treatment centres. This is an update of a Cochrane review first published in 2005, and previously updated in 2008. To assess the benefits and adverse effects of protein substitute, its dosage, and distribution of dose in children and adults with phenylketonuria who are adhering to a low-phenylalanine diet. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which consists of references identified from comprehensive electronic database searches and hand searches of relevant journals and abstract books of conference proceedings. We also contacted manufacturers of the phenylalanine-free and low-phenylalanine protein substitutes for any data from published and unpublished randomised controlled trials.Date of the most recent search of the Group's Inborn Errors of Metabolism Trials Register: 03 April 2014. All randomised or quasi-randomised controlled trials comparing: any dose of protein substitute with no protein substitute; an alternative dosage; or the same dose, but given as frequent small doses throughout the day compared with the same total daily dose given as larger boluses less frequently. Both authors independently extracted data and assessed trial quality. Three trials (69 participants) are included in this review. One trial investigated the use of protein substitute in 16 participants, while a further two trials investigated the

  6. Managing demand uncertainty: probabilistic selling versus inventory substitution

    OpenAIRE

    Zhang, Y.; Hua, Guowei; Wang, Shouyang; Zhang, Juliang; Fernández Alarcón, Vicenç

    2018-01-01

    Demand variability is prevailing in the current rapidly changing business environment, which makes it difficult for a retailer that sells multiple substitutable products to determine the optimal inventory. To combat demand uncertainty, both strategies of inventory substitution and probabilistic selling can be used. Although the two strategies differ in operation, we believe that they share a common feature in combating demand uncertainty by encouraging some customers to give up some specific ...

  7. Factor and Organizational Substitutions to Minimize Costs in the Navy

    Science.gov (United States)

    2013-12-01

    than mere labour for capital substitutions if the objective is one of cost minimization. Static input substitution principle that cheaper inputs...produced? Is the correct mix of inputs being used? While advanced treatments of production theory can be found in microeconomics textbooks (e.g... Microeconomic Theory, 3rd Edition, Prentice Hall Johnson, D.C. et al. (2009), “Managing Change on Complex Programs: VIRGINIA Class Cost Reduction,” Naval

  8. Currency Substitution and The Law of One Price

    OpenAIRE

    Gabriele Camera; Johannes Winkler

    2000-01-01

    We study endogenous currency substitution in a decentralized trade environment. Sellers maximize profits from sales of imperfectly substitutable goods by posting prices in either one of two currencies. A unique symmetric equilibrium exists where goods are priced only in the local currency. This occurs if foreign trade is sporadic, there is sufficient but not excessive liquidity, and discounting is low. Excess or scarcity of liquidity, however, induces sellers to extract all surplus from buyer...

  9. Diastereoselective Au-Catalyzed Allene Cycloisomerizations to Highly Substituted Cyclopentenes.

    Science.gov (United States)

    Reeves, Ryan D; Phelps, Alicia M; Raimbach, William A T; Schomaker, Jennifer M

    2017-07-07

    Site- and regiocontrolled Au-catalyzed allene carbocyclizations furnish highly substituted cyclopentenes in >1:1 dr. Significant substitution on the substrate is tolerated, with potential to install five contiguous stereocenters after alkene functionalization. Major challenges include identifying a Au/Cu catalyst that controls both the relative rates of allene epimerization/cyclization and the facial selectivity in addition of a metal enolate to the allene. Experiments to achieve stereodivergent cyclizations and transform key cyclopentenes into useful synthetic building blocks are described.

  10. A Novel Image Stream Cipher Based On Dynamic Substitution

    OpenAIRE

    Elsharkawi, A.; El-Sagheer, R. M.; Akah, H.; Taha, H.

    2016-01-01

    Recently, many chaos-based stream cipher algorithms have been developed. Traditional chaos stream cipher is based on XORing a generated secure random number sequence based on chaotic maps (e.g. logistic map, Bernoulli Map, Tent Map etc.) with the original image to get the encrypted image, This type of stream cipher seems to be vulnerable to chosen plaintext attacks. This paper introduces a new stream cipher algorithm based on dynamic substitution box. The new algorithm uses one substitution b...

  11. The applied theory of energy substitution in production

    International Nuclear Information System (INIS)

    Thompson, Henry

    2006-01-01

    This paper reviews the applied theory of energy cross price partial elasticities of substitution, and presents it in a transparent fashion. It uses log linear and translog production and cost functions due to their economic properties and convenient estimating forms, but the theory applies other functional forms. The objective is to encourage increased empirical research that would deepen understanding and appreciation of energy substitution. (author)

  12. The elasticity of substitution of superlative price indices

    OpenAIRE

    Petter Frenger

    2005-01-01

    Abstract: The paper presents a method for computing the curvature implicit in the use of superlative price indices. It extends the quadratic lemma and allows us to compute the elasticity of substitution of the underlying preferences in the direction of the observed price change for the Törnqvist and the quadratic mean of order r indices. It derives the expressions for the directional shadow elasticity of substitution and applies the results to the Norwegian CPI data base. Ke...

  13. Think Again: Higher Elasticity of Substitution Increases Economic Resilience

    OpenAIRE

    P. Dumas; S. Hallegatte

    2009-01-01

    This paper shows that, counter-intuitively, a higher elasticity of substitution in model production function can lead to reduced economic resilience and larger vulnerability to shocks in production factor prices. This result is due to the fact that assuming a higher elasticity of substitution requires a recalibration of the production function parameters to keep the model initial state unchanged. This result has consequences for economic analysis, e.g., on the economic vulnerability to climat...

  14. Laser ablation of Bi-substituted gadolinium iron garnet films

    International Nuclear Information System (INIS)

    Watanabe, N.; Hayashida, K.; Kawano, K.; Higuchi, K.; Ohkoshi, M.; Tsushima, K.

    1995-01-01

    Bi-substituted gadolinium iron garnet films were deposited by laser ablation. The composition, the structure and the magnetic properties of the films were found to be strongly dependent both on the compositions of the targets and on the pressure of oxygen. The highest values of Bi-substitution up to x=1.44 with uniform composition were obtained, after annealing in air. ((orig.))

  15. Anthropogenic areas as incidental substitutes for original habitat.

    Science.gov (United States)

    Martínez-Abraín, Alejandro; Jiménez, Juan

    2016-06-01

    One speaks of ecological substitutes when an introduced species performs, to some extent, the ecosystem function of an extirpated native species. We suggest that a similar case exists for habitats. Species evolve within ecosystems, but habitats can be destroyed or modified by natural and human-made causes. Sometimes habitat alteration forces animals to move to or remain in a suboptimal habitat type. In that case, the habitat is considered a refuge, and the species is called a refugee. Typically refugee species have lower population growth rates than in their original habitats. Human action may lead to the unintended generation of artificial or semiartificial habitat types that functionally resemble the essential features of the original habitat and thus allow a population growth rate of the same magnitude or higher than in the original habitat. We call such areas substitution habitats and define them as human-made habitats within the focal species range that by chance are partial substitutes for the species' original habitat. We call species occupying a substitution habitat adopted species. These are 2 new terms in conservation biology. Examples of substitution habitats are dams for European otters, wheat and rice fields for many steppeland and aquatic birds, and urban areas for storks, falcons, and swifts. Although substitution habitats can bring about increased resilience against the agents of global change, the conservation of original habitat types remains a conservation priority. © 2016 Society for Conservation Biology.

  16. Si-substituted hydroxyapatite nanopowders: Synthesis, thermal stability and sinterability

    International Nuclear Information System (INIS)

    Bianco, Alessandra; Cacciotti, Ilaria; Lombardi, Mariangela; Montanaro, Laura

    2009-01-01

    Synthetic hydroxyapatites incorporating small amounts of Si have shown improved biological performances in terms of enhanced bone apposition, bone in-growth and cell-mediated degradation. This paper reports a systematic investigation on Si-substituted hydroxyapatite (Si 1.40 wt%) nanopowders produced following two different conventional wet methodologies: (a) precipitation of Ca(NO 3 ) 2 .4H 2 O and (b) titration of Ca(OH) 2 . The influence of the synthesis process on composition, thermal behaviour and sinterability of the resulting nanopowders is studied. Samples were characterised by electron microscopy, induced coupled plasma atomic emission spectroscopy, thermal analysis, infrared spectroscopy, N 2 adsorption measurements, X-ray diffraction and dilatometry. Semicrystalline Si-substituted hydroxyapatite powders made up of needle-like nanoparticles were obtained, the specific surface area ranged between 84 and 110 m 2 /g. Pure and Si-substituted hydroxyapatite nanopowders derived from Ca(NO 3 ) 2 .4H 2 O decomposed around 1000 deg. C. Si-substituted hydroxyapatite nanopowders obtained from Ca(OH) 2 were thermally stable up to 1200 deg. C and showed a distinct decreased thermal stability with respect to the homologous pure sample. Si-substituted hydroxyapatites exhibited higher sintering temperature and increased total shrinkage with respect to pure powders. Nanostructured dense ceramics were obtained by sintering at 1100 deg. C Si-substituted hydroxyapatites derived from Ca(OH) 2

  17. Eosin-sensitized photooxidation of substituted phenylalanines and tyrosines

    Energy Technology Data Exchange (ETDEWEB)

    Rizzuto, F.; Spikes, J.D.

    1977-01-01

    The cosin-sensitized photooxidation of tyrosine and a number of compounds related to tyrosine (substituted phenylalanines) was studied by steady-state kinetic and flash photolysis techniques. In particular, the role of the phenolic group and the amino and carboxyl groups of the alanyl side chain in the photooxidation mechanism was investigated in detail. Several relationships between substrate structure and susceptibility to photooxidation as well as effects of substrate structure on photooxidation mechanisms were found. For example, phenylalanine is not photooxidizable, but substitution of electron-donating (activating) groups such as -OH (as in tyrosine) or -NH/sub 2/ (as in p-aminophenylalanine) results in rapidly photooxidized derivatives. However, substituting deactivating groups such as -Cl (as in p-chlorophenylalanine) or weakly activating groups such as -OCH/sub 3/ (as in 4-methoxyphenylalanine) result in non-photooxidizable derivatives. Substitution of additional activating groups to the ring of hydroxy-substituted phenylalanines results in increased rates of photooxidation, whereas additional deactivating groups result in decreased photooxidation rates. The rate-determining step in the photooxidation mechanism is shown to be dependent on the presence and position of an electron-donating substituent on the benzenoid ring. Only minor involvement of the side chain amino and carboxyl groups was found. Both singlet oxygen and hydrogen abstraction mechanisms are involved in the eosin-sensitized photooxidation of hydroxy-substituted phenylalanines (e.g., tyrosine). The hydrogen abstraction mechanism probably predominates at both pH 8 and 11.

  18. Are Synonymous Substitutions in Flowering Plant Mitochondria Neutral?

    Science.gov (United States)

    Wynn, Emily L; Christensen, Alan C

    2015-10-01

    Angiosperm mitochondrial genes appear to have very low mutation rates, while non-gene regions expand, diverge, and rearrange quickly. One possible explanation for this disparity is that synonymous substitutions in plant mitochondrial genes are not truly neutral and selection keeps their occurrence low. If this were true, the explanation for the disparity in mutation rates in genes and non-genes needs to consider selection as well as mechanisms of DNA repair. Rps14 is co-transcribed with cob and rpl5 in most plant mitochondrial genomes, but in some genomes, rps14 has been duplicated to the nucleus leaving a pseudogene in the mitochondria. This provides an opportunity to compare neutral substitution rates in pseudogenes with synonymous substitution rates in the orthologs. Genes and pseudogenes of rps14 have been aligned among different species and the mutation rates have been calculated. Neutral substitution rates in pseudogenes and synonymous substitution rates in genes are significantly different, providing evidence that synonymous substitutions in plant mitochondrial genes are not completely neutral. The non-neutrality is not sufficient to completely explain the exceptionally low mutation rates in land plant mitochondrial genomes, but selective forces appear to play a small role.

  19. Neutron kerma factors, and water equivalence of some tissue substitutes

    International Nuclear Information System (INIS)

    Singh, V. P.; Badiger, N. M.; Vega C, H. R.

    2014-08-01

    The kerma factors and kerma relative to air and water of 24 compounds used as tissue substitutes were calculated for neutron energy from 2.53 x 10 -8 up to 29 MeV. The kerma ratio of the tissue substitutes relative to air and water were calculated by the ratio of kerma factors of the tissue substitute to air and water respectively. The water equivalence of the selected tissue substitutes was observed above neutron energies 100 eV. Kerma ratio relative to the air for Poly-vinylidene fluoride and Teflon are found to be nearest to unity in very low energy (up to 1 eV) and above 63 eV respectively. It was found that the natural rubber as a water equivalent tissue substitute compound. The results of the kerma factors in our investigation shows a very good agreement with those published in ICRU-44. We found that at higher neutron energies, the kerma factors and kerma ratios of the selected tissue substitute compounds are approximately same, but differences are large for energies below 100 eV. (Author)

  20. Electrophilic-Nucleophilic Dualism of Nickel(II) toward Ni···I Noncovalent Interactions: Semicoordination of Iodine Centers via Electron Belt and Halogen Bonding via σ-Hole.

    Science.gov (United States)

    Bikbaeva, Zarina M; Ivanov, Daniil M; Novikov, Alexander S; Ananyev, Ivan V; Bokach, Nadezhda A; Kukushkin, Vadim Yu

    2017-11-06

    The nitrosoguanidinate complex [Ni{NH═C(NMe 2 )NN(O)} 2 ] (1) was cocrystallized with I 2 and sym-trifluorotriiodobenzene (FIB) to give associates 1·2I 2 and 1·2FIB. Structures of these solid species were studied by XRD followed by topological analysis of the electron density distribution within the framework of Bader's approach (QTAIM) at the M06/DZP-DKH level of theory and Hirshfeld surface analysis. Our results along with inspection of XRD (CCDC) data, accompanied by the theoretical calculations, allowed the identification of three types of Ni···I contacts. The Ni···I semicoordination of the electrophilic nickel(II) center with electron belt of I 2 was observed in 1·2I 2 , the metal-involving halogen bonding between the nucleophilic nickel(II)-d z 2 center and σ-hole of iodine center was recognized and confirmed theoretically in the structure of [FeNi(CN) 4 (IPz)(H 2 O)] n (IPz = 4-N-coordinated 2-I-pyrazine), whereas the arrangement of FIB in 1·2FIB provides a boundary case between the semicoordination and the halogen Ni···I bondings. In 1·2I 2 and 1·2FIB, noncovalent interactions were studied by variable temperature XRD detecting the expansion of noncovalent contacts with preservation of covalent bond lengths upon the temperature increase from 100 to 300 K. The nature and energies of all identified types of the Ni···I noncovalent interactions in the obtained (1·2I 2 and 1·2FIB) and in the previously reported ([FeNi(CN) 4 (IPz)(H 2 O)] n , [NiL 2 ](I 3 ) 2 ·2I 2 (L = o-phenylene-bis(dimethylphosphine), [NiL]I 2 (L = 1,4,8,11-tetra-azacyclotetradecane), Ni(en) 2 ] n [AgI 2 ] 2n (en = ethylenediamine), and [NiL](ClO 4 ) (L = 4-iodo-2-((2-(2-(2-pyridyl)ethylsulfanyl)ethylimino)methyl)-phenolate)) structures were studied theoretically. The estimated strengths of these Ni···I noncovalent contacts vary from 1.6 to 4.1 kcal/mol and, as expected, become weaker on heating. This work is the first emphasizing electrophilic-nucleophilic dualism

  1. Noval 1-substituted-3,5-dimethyl-4-[(substituted phenyl diazenyl] pyrazole derivatives: Synthesis and pharmacological activity

    Directory of Open Access Journals (Sweden)

    Sabir Hussain

    2015-05-01

    Full Text Available Several-1-carbothioamide-3,5-dimethyl-4-[(substituted phenyl diazenyl] pyrazoles 2a–d, 1-(pyridine-4-ylcarbonyl-3,5-dimethyl-4-[(substituted phenyl diazenyl] pyrazoles 3a–d, 1-(5-chloro-6-fluoro-1,3-benzothiazole-2-ylthiocarbamoyl-3,5-dimethyl-4-[(substituted phenyl diazenyl] pyrazoles 4a–d and 1-[(1,2,4-triazole-4-yl carbothioamide]-3,5-dimethyl-4-[(substituted phenyl diazenyl] pyrazoles 5a–d were synthesized. The structures of the newly synthesized compounds were supported by IR, 1H NMR and mass spectral data. These compounds were investigated for their, anti-inflammatory, analgesic, ulcerogenic, lipid peroxidation, antibacterial and antifungal activities. Some of the synthesized compounds showed potent anti-inflammatory activity along with minimal ulcerogenic effect and lipid peroxidation, compared to ibuprofen and flurbiprofen. Some of the tested compounds also showed moderate antimicrobial activity against tested bacterial and fungal strains.

  2. A generalized operational formula based on total electronic densities to obtain 3D pictures of the dual descriptor to reveal nucleophilic and electrophilic sites accurately on closed-shell molecules.

    Science.gov (United States)

    Martínez-Araya, Jorge I

    2016-09-30

    By means of the conceptual density functional theory, the so-called dual descriptor (DD) has been adapted to be used in any closed-shell molecule that presents degeneracy in its frontier molecular orbitals. The latter is of paramount importance because a correct description of local reactivity will allow to predict the most favorable sites on a molecule to undergo nucleophilic or electrophilic attacks; on the contrary, an incomplete description of local reactivity might have serio us consequences, particularly for those experimental chemists that have the need of getting an insight about reactivity of chemical reagents before using them in synthesis to obtain a new compound. In the present work, the old approach based only on electronic densities of frontier molecular orbitals is replaced by the most accurate procedure that implies the use of total electronic densities thus keeping consistency with the essential principle of the DFT in which the electronic density is the fundamental variable and not the molecular orbitals. As a result of the present work, the DD will be able to properly describe local reactivities only in terms of total electronic densities. To test the proposed operational formula, 12 very common molecules were selected as the original definition of the DD was not able to describe their local reactivities properly. The ethylene molecule was additionally used to test the capability of the proposed operational formula to reveal a correct local reactivity even in absence of degeneracy in frontier molecular orbitals. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  3. Introducing a Hydrogen-Bond Donor into a Weakly Nucleophilic Brønsted Base: Alkali Metal Hexamethyldisilazides (MHMDS, M=Li, Na, K, Rb and Cs) with Ammonia.

    Science.gov (United States)

    Neufeld, Roman; Michel, Reent; Herbst-Irmer, Regine; Schöne, Ralf; Stalke, Dietmar

    2016-08-22

    Alkali metal 1,1,1,3,3,3-hexamethyldisilazide (MHMDSs) are one of the most utilised weakly nucleophilic Brønsted bases in synthetic chemistry and especially in natural product synthesis. Like lithium organics, they aggregate depending on the employed donor solvents. Thus, they show different reactivity and selectivity as a function of their aggregation and solvation state. To date, monomeric LiHMDS with monodentate donor bases was only characterised in solution. Since the first preparation of LiHMDS in 1959 by Wannagat and Niederprüm, all efforts to crystallise monomeric LiHMDS in the absence of chelating ligands failed. Herein, we present ammonia adducts of LiHMDS, NaHMDS, KHMDS, RbHMDS and CsHMDS with unprecedented aggregation motifs: 1) The hitherto missing monomeric key compound in the LiHMDS aggregation architectures. Monomeric crystal structures of trisolvated LiHMDS (1) and NaHMDS (2), showing unique intermolecular hydrogen bonds, 2) the unprecedented tetrasolvated KHMDS (3) and RbHMDS (4) dimers and 3) the disolvated CsHMDS (5) dimer with very close intermolecular Si-CH3 ⋅⋅⋅Cs s-block "agostic" interactions have been prepared and characterised by single-crystal X-ray structure analysis. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. 26 CFR 601.505 - Revocation, change in representation and substitution or delegation of representative.

    Science.gov (United States)

    2010-04-01

    ... authorizes the substitution or delegation. An employee of a recognized representative may not be substituted... substitution or delegation of representative. 601.505 Section 601.505 Internal Revenue INTERNAL REVENUE SERVICE... Practice Requirements § 601.505 Revocation, change in representation and substitution or delegation of...

  5. Cannabis as a substitute for alcohol and other drugs

    Directory of Open Access Journals (Sweden)

    Reiman Amanda

    2009-12-01

    Full Text Available Abstract Background Substitution can be operationalized as the conscious choice to use one drug (legal or illicit instead of, or in conjunction with, another due to issues such as: perceived safety; level of addiction potential; effectiveness in relieving symptoms; access and level of acceptance. This practice of substitution has been observed among individuals using cannabis for medical purposes. This study examined drug and alcohol use, and the occurrence of substitution among medical cannabis patients. Methods Anonymous survey data were collected at the Berkeley Patient's Group (BPG, a medical cannabis dispensary in Berkeley, CA. (N = 350 The sample was 68% male, 54% single, 66% White, mean age was 39; 74% have health insurance (including MediCal, 41% work full time, 81% have completed at least some college, 55% make less than $40,000 a year. Seventy one percent report having a chronic medical condition, 52% use cannabis for a pain related condition, 75% use cannabis for a mental health issue. Results Fifty three percent of the sample currently drinks alcohol, 2.6 was the average number of drinking days per week, 2.9 was the average number of drinks on a drinking occasion. One quarter currently uses tobacco, 9.5 is the average number of cigarettes smoked daily. Eleven percent have used a non-prescribed, non OTC drug in the past 30 days with cocaine, MDMA and Vicodin reported most frequently. Twenty five percent reported growing up in an abusive or addictive household. Sixteen percent reported previous alcohol and/or drug treatment, and 2% are currently in a 12-step or other recovery program. Forty percent have used cannabis as a substitute for alcohol, 26% as a substitute for illicit drugs and 66% as a substitute for prescription drugs. The most common reasons given for substituting were: less adverse side effects (65%, better symptom management (57%, and less withdrawal potential (34% with cannabis. Conclusion The substitution of one

  6. Fine structure study on low concentration zinc substituted hydroxyapatite nanoparticles

    International Nuclear Information System (INIS)

    Hu, Wei; Ma, Jun; Wang, Jianglin; Zhang, Shengmin

    2012-01-01

    The fine structure of zinc substituted hydroxyapatite was studied using experimental analysis and first-principles calculations. The synthetic hydroxyapatite nanoparticles containing low Zn concentration show rod-like morphology. The crystallite sizes and unit-cell volumes tended to decrease with the increased Zn concentration according to X-ray diffraction patterns. The Zn K-edge X-ray absorption spectra and fitting results suggest that the hydroxyapatite doped with 0.1 mole% zinc is different in the zinc coordination environments compared with that containing more zinc. The density function theory calculations were performed on zinc substituted hydroxyapatite. Two mechanisms included replacing calcium by zinc and inserting zinc along the hydroxyl column and were investigated, and the related substitution energies were calculated separately. It is found that the substitution energies are negative and lowest for inserting zinc between the two oxygen atoms along the hydroxyl column (c-axis). Combined with the spectral analysis, it is suggested that the inserting mechanism is favored for low concentration zinc substituted hydroxyapatite. Highlights: ► We investigate the fine structure of hydroxyapatite with low content of Zn. ► XANES spectra are similar but a little different at low zinc content. ► Zinc ions influence hydroxyapatite crystal formation and lattice parameters. ► Formation energies are calculated according to plane-wave density function theory. ► Low content of zinc prefers to locate at hydroxyl column in hydroxyapatite lattice.

  7. A test of the substitution-habitat hypothesis in amphibians.

    Science.gov (United States)

    Martínez-Abraín, Alejandro; Galán, Pedro

    2017-12-08

    Most examples that support the substitution-habitat hypothesis (human-made habitats act as substitutes of original habitat) deal with birds and mammals. We tested this hypothesis in 14 amphibians by using percentage occupancy as a proxy of habitat quality (i.e., higher occupancy percentages indicate higher quality). We classified water body types as original habitat (no or little human influence) depending on anatomical, behavioral, or physiological adaptations of each amphibian species. Ten species had relatively high probabilities (0.16-0.28) of occurrence in original habitat, moderate probability of occurrence in substitution habitats (0.11-0.14), and low probability of occurrence in refuge habitats (0.05-0.08). Thus, the substitution-habitat hypothesis only partially applies to amphibians because the low occupancy of refuges could be due to the negligible human persecution of this group (indicating good conservation status). However, low occupancy of refuges could also be due to low tolerance of refuge conditions, which could have led to selective extinction or colonization problems due to poor dispersal capabilities. That original habitats had the highest probabilities of occupancy suggests amphibians have a good conservation status in the region. They also appeared highly adaptable to anthropogenic substitution habitats. © 2017 Society for Conservation Biology.

  8. Fat substitutes in processing of sausages using piramutaba waste.

    Science.gov (United States)

    de Fátima Henriques Lourenço, Lúcia; Dos Santos Galvão, Giane Célia; da Conceição Amaral Ribeiro, Suezilde; de Fátima Amaral Ribeiro, Carmelita; Park, Kil Jin

    2014-07-01

    The aim of this study was to evaluate fat substitute in processing of sausages prepared with surimi of waste from piramutaba filleting. The formulation ingredients were mixed with the fat substitutes added according to a fractional planning 2(4-1), where the independent variables, manioc starch (Ms), hydrogenated soy fat (F), texturized soybean protein (Tsp) and carrageenan (Cg) were evaluated on the responses of pH, texture (Tx), raw batter stability (RBS) and water holding capacity (WHC) of the sausage. Fat substitutes were evaluated in 11 formulations and the results showed that the greatest effects on the responses were found to Ms, F and Cg, being eliminated from the formulation Tsp. To find the best formulation for processing piramutaba sausage was made a complete factorial planning of 2(3) to evaluate the concentrations of fat substitutes in an enlarged range. The optimum condition found for fat substitutes in the sausages formulation were carrageenan (0.51%), manioc starch (1.45%) and fat (1.2%).

  9. Photophysical investigation of cyano-substituted terrylenediimide derivatives.

    Science.gov (United States)

    Kennes, Koen; Baeten, Yannick; Vosch, Tom; Sempels, Wouter; Yordanov, Stoyan; Stappert, Sebastian; Chen, Long; Müllen, Klaus; Hofkens, Johan; Van der Auweraer, Mark; Fron, Eduard

    2014-12-18

    Two new terrylenediimide (TDI) chromophores with cyano substituents in the bay and core area (BCN-TDI and OCN-TDI, respectively) have been characterized by a wide range of techniques, and their applicability for stimulated emission depletion (STED) microscopy has been tested. By cyano substitution an increase of the fluorescence quantum yield and a decrease of the nonradiative rate constant is achieved and attributed to a reduced charge-transfer character of the excited state due to a lower electron density of the TDI core. For BCN-TDI, the substitution in the bay area induces a strong torsional twist in the molecule which, similar to phenoxy bay-perylenediimide (PDI), has a strong effect on the fluorescence lifetime but appears to prevent the aggregation that is observed for OCN-TDI. The single-molecule photobleaching stability of BCN- and OCN-TDI is lower than that of a reference TDI without cyano substitution (C7-TDI), although less so for OCN-TDI. The photophysical properties of the excited singlet state are only slightly influenced by the cyano groups. The observed intense stimulated emission, the pump-dump-probe experiments, and STED single-molecule imaging indicate that STED experiments with the cyano-substituted TDIs are possible. However, because of aggregation and more efficient photobleaching, the performance of BCN- and OCN-TDI is worse than that of the reference compound without cyano groups (C7-TDI). Bay-substituted TDIs are less suitable for STED microscopy.

  10. Synthesis, characterization and investigation of the spectroscopic properties of novel peripherally 2,3,5-trimethylphenoxy substituted Cu and Co phthalocyanines, the computational and experimental studies of the 4-(2,3,5-trimethylphenoxyphthalonitrile

    Directory of Open Access Journals (Sweden)

    Nesuhi Akdemir

    2016-11-01

    Full Text Available 4-(2,3,5-trimethylphenoxyphthalonitrile (3 was firstly prepared via aromatic nucleophilic substitution reaction and characterized by FT-IR, mass spectrometry, 1H and 13C NMR techniques. The molecular structure of the compound (3 was optimized using Density Functional Theory (DFT/B3LYP method with 6-311G(d,p basis set in the ground state. The molecular geometric parameters which were obtained by X-ray single crystal diffraction method and the spectral results were compared with computed bond lengths and angles, vibrational frequencies and 1H, 13C NMR chemical shifts values of the compound (3. Also, Cu(II and Co(II phthalocyanines were synthesized by the treatment of dinitrile derivative with anhydrous CuCl2 or CoCl2 under N2 atmosphere in dry n-pentanol at 140oC. The new compounds have been determined by elemental analysis, FT-IR and electronic absorption. The UV-Vis spectra of the Cu(II and Co(II phthalocyanines were recorded with different concentration in THF and also with different solvents as DMF, DMSO, DCM, CHCl3, toluene.

  11. Pesticide Substitution: Combining Food Safety with Environmental Quality

    DEFF Research Database (Denmark)

    Fantke, Peter

    2015-01-01

    Various pesticides are authorized for use on agricultural food crops. Despite regulatory risk assessments aiming at ensuring consumer and environmental safety, pesticides contribute to human and environmental impacts. Guidance is needed to optimize pesticide use practice and minimize human...... and environmental exposure. Comparative pesticide substitution scenarios are presented to address this need. In a case study on wheat, different pesticides have been compared with respect to their substitution potential with focus on human health. Results demonstrate that health impacts can be reduced up to 99......% by defining adequate substitution scenarios. Comprehensive scenarios need to also consider worker and environmental burden, and information on crop rotation, pest pressure, environmental conditions, application costs and efficacy. Such scenarios help to increase food safety and more sustainable use...

  12. Application of queuing theory in inventory systems with substitution flexibility

    Science.gov (United States)

    Seyedhoseini, S. M.; Rashid, Reza; Kamalpour, Iman; Zangeneh, Erfan

    2015-03-01

    Considering the competition in today's business environment, tactical planning of a supply chain becomes more complex than before. In many multi-product inventory systems, substitution flexibility can improve profits. This paper aims to prepare a comprehensive substitution inventory model, where an inventory system with two substitute products with ignorable lead time has been considered, and effects of simultaneous ordering have been examined. In this paper, demands of customers for both of the products have been regarded as stochastic parameters, and queuing theory has been used to construct a mathematical model. The model has been coded by C++, and it has been analyzed due to a real example, where the results indicate efficiency of proposed model.

  13. Selected polyethylene glycols as DOP substitutes. Addendum 1

    International Nuclear Information System (INIS)

    Gerber, B.V.

    1981-01-01

    The recommendation is made that Polyethylene glycol (PEG) 400 be considered as a substitute for DOP in aerosol generators producing a polydisperse distribution for testing the integrity of filters and for testing respirator fit. Further, the recommendation is made that pentaethylene glycol (PTAEG) and possibly hexaethylene glycol be considered as a substitute for DOP in aerosol generators thermally producing monodisperse aerosol for quality acceptance tests according tu US federal specifications and standards. The toxicology data base available on the polyethylene glycol family of chemical compounds is discussed and the conclusion is drawn that the probability of approval and acceptance as a non-hazardous substance in the filter and filter media test role is high. Data and analysis supporting PTAEG performance equivalent to DOP in the filter and filter media test role are given or referenced. Cost and availability of the substitute materials is discussed. Conclusions based on the present data and information are given and recommendations for further work are made

  14. Substituting fields within the action: Consistency issues and some applications

    International Nuclear Information System (INIS)

    Pons, Josep M.

    2010-01-01

    In field theory, as well as in mechanics, the substitution of some fields in terms of other fields at the level of the action raises an issue of consistency with respect to the equations of motion. We discuss this issue and give an expression which neatly displays the difference between doing the substitution at the level of the Lagrangian or at the level of the equations of motion. Both operations do not commute in general. A very relevant exception is the case of auxiliary variables, which are discussed in detail together with some of their relevant applications. We discuss the conditions for the preservation of symmetries--Noether as well as non-Noether--under the reduction of degrees of freedom provided by the mechanism of substitution. We also examine how the gauge fixing procedures fit in our framework and give simple examples on the issue of consistency in this case.

  15. Tissue reaction and material characteristics of four bone substitutes

    DEFF Research Database (Denmark)

    Jensen, S S; Aaboe, M; Pinholt, E M

    1996-01-01

    and Interpore 500 HA/CC) were implanted into 5-mm bur holes in rabbit tibiae. There was no difference in the amount of newly formed bone around the four biomaterials. Interpore 500 HA/CC resorbed completely, whereas the other three biomaterials did not undergo any detectable biodegradation. Bio......The aim of the present study was to qualitatively and quantitatively compare the tissue reactions around four different bone substitutes used in orthopedic and craniofacial surgery. Cylinders of two bovine bone substitutes (Endobon and Bio-Oss) and two coral-derived bone substitutes (Pro Osteon 500......-Oss was osseointegrated to a higher degree than the other biomaterials. Material characteristics obtained by diffuse reflectance infrared Fourier transform spectrometry analysis and energy-dispersive spectrometry did not explain the differences in biologic behavior....

  16. Synthesis and application of trifluoroethoxy-substituted phthalocyanines and subphthalocyanines

    Directory of Open Access Journals (Sweden)

    Satoru Mori

    2017-10-01

    Full Text Available Phthalocyanines and subphthalocyanines are attracting attention as functional dyes that are applicable to organic solar cells, photodynamic therapy, organic electronic devices, and other applications. However, phthalocyanines are generally difficult to handle due to their strong ability to aggregate, so this property must be controlled for further applications of phthalocyanines. On the other hand, trifluoroethoxy-substituted phthalocyanines are known to suppress aggregation due to repulsion of the trifluoroethoxy group. Furthermore, the electronic characteristics of phthalocyanines are significantly changed by the strong electronegativity of fluorine. Therefore, it is expected that trifluoroethoxy-substituted phthalocyanines can be applied to new industrial fields. This review summarizes the synthesis and application of trifluoroethoxy-substituted phthalocyanine and subphthalocyanine derivatives.

  17. Electronic and magnetic properties of Si substituted Fe3Ge

    International Nuclear Information System (INIS)

    Shanavas, K. V.; McGuire, Michael A.; Parker, David S.

    2015-01-01

    Using first principles calculations, we studied the effect of Si substitution in the hexagonal Fe 3 Ge. We find the low temperature magnetic anisotropy in this system to be planar and originating mostly from the spin-orbit coupling in Fe-d states. Reduction of the unitcell volume reduces the magnitude of in-plane magnetic anisotropy, eventually turning it positive which reorients the magnetic moments to the axial direction. Substituting Ge with the smaller Si ions also increases the anisotropy, potentially enhancing the region of stability of the axial magnetization, which is beneficial for magnetic applications such as permanent magnets. Our experimental measurements on samples of Fe 3 Ge 1−x Si x confirm these predictions and show that substitution of about 6% of the Ge with Si increases by approximately 35 K the temperature range over which anisotropy is uniaxial

  18. Synthesis of Randomly Substituted Anionic Cyclodextrins in Ball Milling

    Directory of Open Access Journals (Sweden)

    László Jicsinszky

    2017-03-01

    Full Text Available A number of influencing factors mean that the random substitution of cyclodextrins (CD in solution is difficult to reproduce. Reaction assembly in mechanochemistry reduces the number of these factors. However, lack of water can improve the reaction outcomes by minimizing the reagent’s hydrolysis. High-energy ball milling is an efficient, green and simple method for one-step reactions and usually reduces degradation and byproduct formation. Anionic CD derivatives have successfully been synthesized in the solid state, using a planetary ball mill. Comparison with solution reactions, the solvent-free conditions strongly reduced the reagent hydrolysis and resulted in products of higher degree of substitution (DS with more homogeneous DS distribution. The synthesis of anionic CD derivatives can be effectively performed under mechanochemical activation without significant changes to the substitution pattern but the DS distributions were considerably different from the products of solution syntheses.

  19. How Firms Substitute for Authority in Strategic Decision-Making

    DEFF Research Database (Denmark)

    Dobrajska, Magdalena; Billinger, Stephan; Becker, Markus C.

    Strategic decisions are often made by multiple organizational members who form decision-making structures specialized for a given strategic decision. We study a series of strategic decisions in a business unit of a global Fortune 500 firm, identifying for each decision the hierarchical...... takes place in response to changes in decision characteristics, including decision complexity, decision importance, CEO proximity, and the degree to which a decision is routine. We show various manifestations of the substitution mechanism and discuss implications for strategic decision-making....... and departmental positions of all participating organizational members. We find that firms substitute between different structural components in decision-making structures to combine hierarchical authority with cross-departmental coordination and redundant knowledge. This substitution between structural components...

  20. Substitution of sugar-sweetened beverages with other beverage alternatives

    DEFF Research Database (Denmark)

    Zheng, Miaobing; Allman-Farinelli, Margaret; Heitmann, Berit Lilienthal

    2015-01-01

    alternatives on long-term health outcomes. METHOD: We systematically retrieved studies from six electronic databases from inception to November 2013. Prospective cohort studies and randomized controlled trials (RCTs) examining the effects of substituting beverage alternatives for SSBs on long-term health...... to high. Evidence from both cohort studies and RCTs showed substitution of SSBs by various beverage alternatives was associated with long-term lower energy intake and lower weight gain. However, evidence was insufficient to draw conclusions regarding the effect of beverage substitution on other health...... outcomes, and which beverage alternative is the best choice. CONCLUSIONS: Although studies on this topic are sparse, the available evidence suggests a potential beneficial effect on body weight outcomes when SSBs are replaced by water or low-calorie beverages. Further studies in this area are warranted...

  1. Effect of substitution groups in carbon-13 NMR of tri-substituted camphors; Efeitos de substituintes em RMN de carbono-13 de canforas 3-substituidas

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, Carlos R; Rittner, Roberto [Universidade Estadual de Campinas, SP (Brazil). Inst. de Quimica; Basso, Ernani A [Universidade Estadual de Maringa, PR (Brazil). Dept. de Quimica Inorganica

    1994-12-31

    This work presents and discusses the empirical effects of substitution groups in the carbon-13 NMR spectra of tri-substituted camphors and their correlation with the chemical properties of such substitution groups such as electronegativity. The obtained results are presented and discussed

  2. Carbonate hydroxyapatite and silicon-substituted carbonate hydroxyapatite

    DEFF Research Database (Denmark)

    Bang, L T; Long, B D; Othman, R

    2014-01-01

    The present study investigates the chemical composition, solubility, and physical and mechanical properties of carbonate hydroxyapatite (CO3Ap) and silicon-substituted carbonate hydroxyapatite (Si-CO3Ap) which have been prepared by a simple precipitation method. X-ray diffraction (XRD), Fourier......(3-)) site and also entered simultaneously into the hydroxyapatite structure. The Si-substituted CO3Ap reduced the powder crystallinity and promoted ion release which resulted in a better solubility compared to that of Si-free CO3Ap. The mean particle size of Si-CO3Ap was much finer than that of CO3Ap...

  3. Heterogenous Intertemporal Elasticity of Substitution and Relative Risk Aversion

    DEFF Research Database (Denmark)

    Khorunzhina, Natalia; Gayle, Wayne-Roy

    This paper investigates the existence and degree of variation across house holds and over time in the intertemporal elasticity of substitution (IES) and the coefficient of relative risk aversion (RRA) that is generated by habit forming preferences. To do so, we develop a new nonlinear GMM estimator...... in food consumption. Using these estimates, we develop bounds for the expectation of the implied heterogenous intertemporal elasticity of substitution and relative risk aversion that account for measurement errors and compute asymptotically valid confidence intervals on these bounds. We find...

  4. Exfoliation and thermal transformations of Nb-substituted layered titanates

    DEFF Research Database (Denmark)

    Song, H.; Sjåstad, Anja O.; Fjellvåg, Helmer

    2011-01-01

    Single-layer Nb-substituted titanate nanosheets of ca. 1 nm thickness were obtained by exfoliating tetrabutylammonium (TBA)-intercalated Nb-substituted titanates in water. AFM images and turbidity measurements reveal that the exfoliated nanosheets crack and corrugate when sonicated. Upon heating...... factors for increasing the transformation temperatures for conversion of the nanosheets to anatase and finally into rutile. It is further tempting to link the delay in crystallization to morphology limitations originating from the nanosheets. The present work shows that layered Nb-titanates...

  5. Minority anion substitution by Ni in ZnO

    CERN Document Server

    Pereira, Lino Miguel da Costa; Correia, João Guilherme; Amorim, Lígia Marina; Silva, Daniel José; David-Bosne, Eric; Decoster, Stefan; da Silva, Manuel Ribeiro; Temst, Kristiaan; Vantomme, André

    2013-01-01

    We report on the lattice location of implanted Ni in ZnO using the $\\beta$− emission channeling technique. In addition to the majority substituting for the cation (Zn), a significant fraction of the Ni atoms occupy anion (O) sites. Since Ni is chemically more similar to Zn than it is to O, the observed O substitution is rather puzzling. We discuss these findings with respect to the general understanding of lattice location of dopants in compound semiconductors. In particular, we discuss potential implications on the magnetic behavior of transition metal doped dilute magnetic semiconductors.

  6. The electronic configuration of substitutional Fe in silicon

    CERN Document Server

    Weyer, G; Fanciulli, M; Fedosseev, V; Gunnlaugsson, H P; Mishin, V I; Sielemann, R

    1999-01-01

    Ion implantations of radioactive /sup 57/Mn/sup +/ into differently doped silicon single crystals held at 300-600 K have been utilized for /sup 57/Fe Mossbauer studies of interstitial and substitutional Fe. Site and charge state assignments have been made on the basis of the determined hyperfine interaction parameters and Debye temperatures. Substantial fractions of substitutional /sup 57/Mn probe atoms are proposed to occur due to annealing reactions. This site is maintained in the subsequent decay to /sup 57/Fe by

  7. Antimalarial Activity of C-10 Substituted Triazolyl Artemisinin.

    Science.gov (United States)

    Park, Gab-Man; Park, Hyun; Oh, Sangtae; Lee, Seokjoon

    2017-12-01

    We synthesized C-10 substituted triazolyl artemisinins by the Huisgen cycloaddition reaction between dihydroartemisinins (2) and variously substituted 1, 2, 3-triazoles (8a-8h). The antimalarial activities of 32 novel artemisinin derivatives were screened against a chloroquine-resistant parasite. Among them, triazolyl artemisinins with electron-withdrawing groups showed stronger antimalarial activities than those shown by the derivatives having electron-donating groups. In particularly, m-chlorotriazolyl artemisinin (9d-12d) showed antimalarial activity equivalent to that of artemisinin and could be a strong drug candidate.

  8. Synthesis and biological evaluation of 2-substituted benzimidazole derivatives

    Directory of Open Access Journals (Sweden)

    Gurusamy Mariappan

    2015-09-01

    Full Text Available A novel series of 2-substituted benzimidazole derivatives (3a–3j were synthesized by the reaction of 2-chloro methyl benzimidazole with substituted primary aromatic amines. All the compounds were characterized by UV, IR, 1H NMR, mass spectral data and CHN elemental analysis. The synthesized derivatives were screened for analgesic and anti-inflammatory activities. All the compounds showed significant effect at 100 mg/kg p.o. and the experimental data are statistically significant at p < 0.01 level.

  9. A Novel Non-Toxic Xylene Substitute (SBO) for Histology

    OpenAIRE

    Kunhua, Wang; Chuming, Fan; Tao, Lai; Yanmei, Yang; Xin, Yang; Xiaoming, Zhang; Xuezhong, Guo; Xun, Lai

    2011-01-01

    Xylene has been generally used as a clearing and deparaffinizing agent in histology. Because of the potential toxic and flammable nature of xylene, its substitutes have been introduced into some laboratories. In this study, we introduced a novel, non-toxic xylene substitute (SBO), which was generated through a mixture of 86% of white oil No.2 and 14% of N-heptane. SBO had a high boiling point (188°C) and flash point (144°C) coupled with a scentless and decreased volatility. To compare the eff...

  10. Researcher’s Perspective of Substitution Method on Text Steganography

    Science.gov (United States)

    Zamir Mansor, Fawwaz; Mustapha, Aida; Azah Samsudin, Noor

    2017-08-01

    The linguistic steganography studies are still in the stage of development and empowerment practices. This paper will present several text steganography on substitution methods based on the researcher’s perspective, all scholar paper will analyse and compared. The objective of this paper is to give basic information in the substitution method of text domain steganography that has been applied by previous researchers. The typical ways of this method also will be identified in this paper to reveal the most effective method in text domain steganography. Finally, the advantage of the characteristic and drawback on these techniques in generally also presented in this paper.

  11. Klebsiella pneumoniae Carbapenemase-2 (KPC-2, Substitutions at Ambler Position Asp179, and Resistance to Ceftazidime-Avibactam: Unique Antibiotic-Resistant Phenotypes Emerge from β-Lactamase Protein Engineering

    Directory of Open Access Journals (Sweden)

    Melissa D. Barnes

    2017-10-01

    Full Text Available The emergence of Klebsiella pneumoniae carbapenemases (KPCs, β-lactamases that inactivate “last-line” antibiotics such as imipenem, represents a major challenge to contemporary antibiotic therapies. The combination of ceftazidime (CAZ and avibactam (AVI, a potent β-lactamase inhibitor, represents an attempt to overcome this formidable threat and to restore the efficacy of the antibiotic against Gram-negative bacteria bearing KPCs. CAZ-AVI-resistant clinical strains expressing KPC variants with substitutions in the Ω-loop are emerging. We engineered 19 KPC-2 variants bearing targeted mutations at amino acid residue Ambler position 179 in Escherichia coli and identified a unique antibiotic resistance phenotype. We focus particularly on the CAZ-AVI resistance of the clinically relevant Asp179Asn variant. Although this variant demonstrated less hydrolytic activity, we demonstrated that there was a prolonged period during which an acyl-enzyme intermediate was present. Using mass spectrometry and transient kinetic analysis, we demonstrated that Asp179Asn “traps” β-lactams, preferentially binding β-lactams longer than AVI owing to a decreased rate of deacylation. Molecular dynamics simulations predict that (i the Asp179Asn variant confers more flexibility to the Ω-loop and expands the active site significantly; (ii the catalytic nucleophile, S70, is shifted more than 1.5 Å and rotated more than 90°, altering the hydrogen bond networks; and (iii E166 is displaced by 2 ÅÅ when complexed with ceftazidime. These analyses explain the increased hydrolytic profile of KPC-2 and suggest that the Asp179Asn substitution results in an alternative complex mechanism leading to CAZ-AVI resistance. The future design of novel β-lactams and β-lactamase inhibitors must consider the mechanistic basis of resistance of this and other threatening carbapenemases.

  12. Can hydroxylamine be a more potent nucleophile for the reactivation of tabun-inhibited AChE than prototype oxime drugs? An answer derived from quantum chemical and steered molecular dynamics studies.

    Science.gov (United States)

    Lo, Rabindranath; Ganguly, Bishwajit

    2014-07-29

    Organophosphorus nerve agents are highly toxic compounds which strongly inhibit acetylcholinesterase (AChE) in the blood and in the central nervous system (CNS). Tabun is one of the highly toxic organophosphorus (OP) compounds and is resistant to many oxime drugs formulated for the reactivation of AChE. The reactivation mechanism of tabun-conjugated AChE with various drugs has been examined with density functional theory and ab initio quantum chemical calculations. The presence of a lone-pair located on the amidic group resists the nucleophilic attack at the phosphorus center of the tabun-conjugated AChE. We have shown that the newly designed drug candidate N-(pyridin-2-yl)hydroxylamine, at the MP2/6-31+G*//M05-2X/6-31G* level in the aqueous phase with the polarizable continuum solvation model (PCM), is more effective in reactivating the tabun-conjugated AChE than typical oxime drugs. The rate determining activation barrier with N-(pyridin-2-yl)hydroxylamine was found to be ∼1.7 kcal mol(-1), which is 7.2 kcal mol(-1) lower than the charged oxime trimedoxime (one of the most efficient reactivators in tabun poisonings). The greater nucleophilicity index (ω(-)) and higher CHelpG charge of pyridinylhydroxylamine compared to TMB4 support this observation. Furthermore, we have also examined the reactivation process of tabun-inhibited AChE with some other bis-quaternary oxime drug candidates such as methoxime (MMB4) and obidoxime. The docking analysis suggests that charged bis-quaternary pyridinium oximes have greater binding affinity inside the active-site gorge of AChE compared to the neutral pyridinylhydroxylamine. The peripheral ligand attached to the neutral pyridinylhydroxylamine enhanced the binding with the aromatic residues in the active-site gorge of AChE through effective π-π interactions. Steered molecular dynamics (SMD) simulations have also been performed with the charged oxime (TMB4) and the neutral hydroxylamine. From protein-drug interaction

  13. Synthesis of Novel Benzimidazolyl-substituted Acrylonitriles and Amidino-substituted Benzimidazo[1,2-a]Quinolines

    Directory of Open Access Journals (Sweden)

    Grace Karminski-Zamola

    2006-08-01

    Full Text Available A series of novel benzimidazole derivatives 3-10 were synthesized. Benzimidazolyl-substituted acrylonitriles 3 and 4 underwent a photochemical dehydrocyclization reaction to give the corresponding mono- and dicyano-substituted benzimidazo[1,2-a] quinolines 5 and 6. Pinner reaction of these compounds did not give the expected mono- and diamidines, but rather only compounds 7-10, with amido groups at 6-position were isolated. A mechanism for the reaction is proposed. Acyclic compounds 3 and 4, as well as cyclic benzimidazo[1,2-a]quinolines 5-8, exhibit interesting spectroscopic properties and are potential biologically active compounds.

  14. Nucleophilicities of Lewis Bases B and Electrophilicities of Lewis Acids A Determined from the Dissociation Energies of Complexes B⋯A Involving Hydrogen Bonds, Tetrel Bonds, Pnictogen Bonds, Chalcogen Bonds and Halogen Bonds

    Directory of Open Access Journals (Sweden)

    Ibon Alkorta

    2017-10-01

    Full Text Available It is shown that the dissociation energy D e for the process B⋯A = B + A for 250 complexes B⋯A composed of 11 Lewis bases B (N2, CO, HC≡CH, CH2=CH2, C3H6, PH3, H2S, HCN, H2O, H2CO and NH3 and 23 Lewis acids (HF, HCl, HBr, HC≡CH, HCN, H2O, F2, Cl2, Br2, ClF, BrCl, H3SiF, H3GeF, F2CO, CO2, N2O, NO2F, PH2F, AsH2F, SO2, SeO2, SF2, and SeF2 can be represented to good approximation by means of the equation D e = c ′ N B E A , in which N B is a numerical nucleophilicity assigned to B, E A is a numerical electrophilicity assigned to A, and c ′ is a constant, conveniently chosen to have the value 1.00 kJ mol−1 here. The 250 complexes were chosen to cover a wide range of non-covalent interaction types, namely: (1 the hydrogen bond; (2 the halogen bond; (3 the tetrel bond; (4 the pnictogen bond; and (5 the chalcogen bond. Since there is no evidence that one group of non-covalent interaction was fitted any better than the others, it appears the equation is equally valid for all the interactions considered and that the values of N B and E A so determined define properties of the individual molecules. The values of N B and E A can be used to predict the dissociation energies of a wide range of binary complexes B⋯A with reasonable accuracy.

  15. Nucleophilicities of Lewis Bases B and Electrophilicities of Lewis Acids A Determined from the Dissociation Energies of Complexes B⋯A Involving Hydrogen Bonds, Tetrel Bonds, Pnictogen Bonds, Chalcogen Bonds and Halogen Bonds.

    Science.gov (United States)

    Alkorta, Ibon; Legon, Anthony C

    2017-10-23

    It is shown that the dissociation energy D e for the process B⋯A = B + A for 250 complexes B⋯A composed of 11 Lewis bases B (N₂, CO, HC≡CH, CH₂=CH₂, C₃H₆, PH₃, H₂S, HCN, H₂O, H₂CO and NH₃) and 23 Lewis acids (HF, HCl, HBr, HC≡CH, HCN, H₂O, F₂, Cl₂, Br₂, ClF, BrCl, H₃SiF, H₃GeF, F₂CO, CO₂, N₂O, NO₂F, PH₂F, AsH₂F, SO₂, SeO₂, SF₂, and SeF₂) can be represented to good approximation by means of the equation D e = c ' N B E A , in which N B is a numerical nucleophilicity assigned to B, E A is a numerical electrophilicity assigned to A, and c ' is a constant, conveniently chosen to have the value 1.00 kJ mol -1 here. The 250 complexes were chosen to cover a wide range of non-covalent interaction types, namely: (1) the hydrogen bond; (2) the halogen bond; (3) the tetrel bond; (4) the pnictogen bond; and (5) the chalcogen bond. Since there is no evidence that one group of non-covalent interaction was fitted any better than the others, it appears the equation is equally valid for all the interactions considered and that the values of N B and E A so determined define properties of the individual molecules. The values of N B and E A can be used to predict the dissociation energies of a wide range of binary complexes B⋯A with reasonable accuracy.

  16. More similar but less satisfying: comparing preferences for and the efficacy of within- and cross-category substitutes for food

    OpenAIRE

    Huh, Young Eun; Vosgerau, Joachim; Morewedge, Carey

    2016-01-01

    When people cannot get what they want, they often satisfy their desire by consuming a substitute. Substitutes can originate from within the taxonomic category of the desired stimulus (i.e., within-category substitutes) or from a different taxonomic category that serves the same basic goal (i.e., cross-category substitutes). Both a store-brand chocolate (within-category substitute) and a granola bar (cross-category substitute), for example, can serve as substitutes for gourmet chocolate. Here,...

  17. Synthesis of 1-Substituted-4-(Pyridin-4-yl)

    African Journals Online (AJOL)

    Purpose: To synthesize a new series of 1-substituted-4-(pyridin-4-yl) [1,2,4] triazolo [4,3-a]quinazolin- 5(4H)-ones and evaluate them for H1-antihistaminic activity with negligible side effects in guinea pigs. Methods: The synthesized compounds were characterized by Infrared spectroscopy (IR), proton nuclear magnetic ...

  18. Stiffness compatibility of coralline hydroxyapatite bone substitute under dynamic loading

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    When hydroxyapatite bone substitutes are implanted in human bodies,bone tissues will grow into their porous structure,which will reinforce their strength and stiffness.The concept of mechanical com-patibility of bone substitutes implies that their mechanical properties are similar to the bone tissues around,as if they were part of the bone.The mechanical compatibility of bone substitutes includes both static and dynamic behavior,due to the mechanical properties of bone depending on the strain rate.In this study,split Hopkinson pressure bar technique(SHPB) was employed to determine the dy-namic mechanical properties of coralline hydroxyapatite,bones with and bones without organic com-ponents,and their dynamic stress-strain curves of the three materials were obtained.The mechanical effects of collagens in bone were assessed,by comparing the difference between the Young’s moduli of the three materials.As the implanted bone substitute becomes a part of bone,it can be regarded as an inclusion composite.The effective modulus of the composite was also evaluated in order to estimate its mechanical compatibility on stiffness.The evaluated result shows that the suitable porosity of HA is 0.8,which is in favor of both static and dynamic stiffness compatibility.

  19. Stiffness compatibility of coralline hydroxyapatite bone substitute under dynamic loading

    Institute of Scientific and Technical Information of China (English)

    REN ChaoFeng; HOU ZhenDe; ZHAO Wei

    2009-01-01

    When hydroxyapatite bone substitutes are implanted in human bodies, bone tissues will grow into their porous structure, which will reinforce their strength and stiffness. The concept of mechanical com-patibility of bone substitutes implies that their mechanical properties are similar to the bone tissues around, as if they were part of the bone. The mechanical compatibility of bone substitutes includes both static and dynamic behavior, due to the mechanical properties of bone depending on the strain rate. In this study, split Hopkinson pressure bar technique (SHPB) was employed to determine the dy-namic mechanical properties of coralline hydroxyapatite, bones with and bones without organic com-ponents, and their dynamic stress-strain curves of the three materials were obtained. The mechanical effects of collagens in bone were assessed, by comparing the difference between the Young's moduli of the three materials. As the implanted bone substitute becomes a part of bone, it can be regarded as an inclusion composite. The effective modulus of the composite was also evaluated in order to estimate its mechanical compatibility on stiffness. The evaluated result shows that the suitable porosity of HA is0.8, which is in favor of both static and dynamic stiffness compatibility.

  20. Clinical review: impact of statin substitution policies on patient outcomes

    NARCIS (Netherlands)

    Atar, Dan; Carmena, Rafael; Clemmensen, Peter; K-Laflamme, Annik; Wassmann, Sven; Lansberg, Peter; Hobbs, Richard

    2009-01-01

    The increasing awareness of cost issues in health care has led to the increasing use of policy-driven substitution of branded for generic medications, particularly relative to statin treatment for cardiovascular diseases. While there are potential short-term health care savings, the consequences for