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Sample records for 3-hydroxy-2-formylpyridine semicarbazone synthesis

  1. An Efficient Procedure for Microscale Synthesis of Semicarbazones

    ERIC Educational Resources Information Center

    Pandita, Sangeeta; Goyal, Samta; Passey, Sarita

    2004-01-01

    A successful microscale fusion of semicarbazones, or transformation of carbonyl compounds into semicarbazones is performed through an effective grinding system. The donning of protective attire is advised to avoid the hazardous effects of semicarbazide hydrochloride during the fusion process.

  2. Synthesis and Antibacterial Activity of Novel Hydroxy Semicarbazone Derivatives

    PubMed Central

    Hariri, Elham; Mahboubi, Arash; Fathi, Mohammad; Rahmani, Parisa; Haj Mohammad Ebrahim Tehrani, Kamaleddin; Babaeian, Mohammad; Mashayekhi, Vida; Kobarfard, Farzad

    2016-01-01

    A series of hydroxyl semicarbazone derivatives of substituted diaryl ketones and acetophenones were synthesized and their structures were confirmed by analytical and spectroscopic methods including elemental analysis, infrared and nuclear magnetic resonance spectroscopy. The derivatives were prepared by a condensation reaction between N-hydroxy semicarbazide and substituted diaryl ketones or acetophenones leading to the desired hydroxysemicarbazones with excellent purity. The synthesized hydrazones were then evaluated for their inhibitory activity against bacterial strains including S. aureus, E. Coli, P. aeruginosa, K. pneumonia and M. luteus. Among the tested derivatives, compounds 2, 6 and 7 exhibited the highest bioactivity. Analysis of the activity data suggests that hydrophilicity is an important factor for the bioactivity of compounds 2 and 6 and also their selectivity over the gram-negative bacteria. PMID:28228801

  3. Copper-catalyzed N-arylation of semicarbazones for the synthesis of aza-arylglycine-containing aza-peptides.

    PubMed

    Proulx, Caroline; Lubell, William D

    2010-07-02

    Parallel synthesis of 13 aza-arylglycine peptides, based on the hexapeptide sequence of Growth Hormone Releasing Peptide-6 (GHRP-6), was accomplished via selective N-arylation of a semicarbazone peptide building block anchored on Rink amide resin. Aza-peptides possessing aza-indolylglycine and aza-imidazoylglycine residues were obtained through use of the corresponding heteroaryl iodides, yielding, respectively, aza-Trp and aza-His peptidomimics. CD spectroscopy indicated the propensity for aza-peptides, containing aza-arylglycines at the Trp(4) position of the GHRP-6 sequence, to adopt beta-turns.

  4. Design, synthesis and in vitro trypanocidal and leishmanicidal activities of novel semicarbazone derivatives.

    PubMed

    Alves, Marina A; de Queiroz, Aline C; Alexandre-Moreira, Magna Suzana; Varela, Javier; Cerecetto, Hugo; González, Mercedes; Doriguetto, Antonio C; Landre, Iara M; Barreiro, Eliezer J; Lima, Lídia M

    2015-07-15

    Trypanosomatids are protozoan parasites that cause various diseases in human, such as leishmaniasis, Chagas disease and sleeping sickness. The highly syntenic genomes of the trypanosomatid species lead the assumption that they can encode similar proteins, indicating the possibility to design new antitrypanosomatid drugs with dual trypanosomicidal and leishmanicidal activities. In this work a series of compounds (6a-h and 7a-h), containing a semicarbazone scaffold as a peptide mimetic framework, was designed and synthesized. From this series compound 7g (LASSBio-1483) highlighted, showing dual in vitro trypanosomicidal and leishmanicidal activities, with potency similar to the standard drugs nifurtimox and pentamidine. This data, taken together with its good in silico druglikeness profile and its great chemical and plasma stability, make LASSBio-1483 (7g) a new antitrypanosomatid lead-candidate.

  5. Synthesis, characterization and chemical properties of 1-((E)-2-pyridinylmethylidene)semicarbazone manganese(II) and iron(II) complexes

    NASA Astrophysics Data System (ADS)

    Garbelini, Ellery Regina; Martin, Maria da Graça M. B.; Back, Davi Fernando; Evans, David John; Müller-Santos, Marcelo; Ribeiro, Ronny Rocha; Lang, Ernesto Schulz; Nunes, Fábio Souza

    2012-01-01

    Manganese(II) perchlorate and iron(II) chloride react with 2-formylpyridine semicarbazone (HCSpy) in boiling ethanol to produce [Mn II(HSCpy) 2](ClO 4) 2·C 2H 5OH and [Fe IICl(HSCpy)]Cl. The distorted octahedral manganese complex crystallizes in the triclinic system with space group P(-1). The ligand HSCpy is tridentate and is coordinated through two nitrogen and one oxygen atoms. Comparison of the bond distances with analogous transition metal complexes that have the same geometry revealed longer bonds for the manganese derivative, an outcome that correlates well with the radius of the metal ions. The iron(II) ion is tetracoordinated to one semicarbazone and one chloride. Mass spectrometry, conductivity measurements, Mössbauer, UV-VIS, FTIR and elemental analysis were all in accordance with the proposed composition and the plausible geometry of [FeCl(HSCpy)]Cl. Mass spectrometry unequivocally detected the presence of the [FeCl(HSCpy)] + ion with a m/ z of 254.97 and intensity of 2 × 10 5.

  6. Imidazole incorporated semicarbazone derivatives as a new class of anticonvulsants: design, synthesis and in-vivo screening.

    PubMed

    Amir, Mohammad; Ali, Israr; Hassan, Mohd Zaheen

    2013-06-01

    A series of novel imidazole incorporated semicarbazones was synthesized using an appropriate synthetic route and characterized by spectral analysis (IR, 1H NMR, 13C NMR and Mass). The anticonvulsant activity of the synthesized compounds was determined using doses of 30, 100, and 300 mg kg-1 against maximal electroshock seizure (MES), subcutaneous pentylenetetrazole (scPTZ) induced seizure and minimal neurotoxicity test. Six compounds exhibited protection in both models and 2-(1-(4-chlorophenyl)-2-(1H-imidazol-1-yl)ethylidene)-N-p-tolylsemicarbazone emerged as the most active compound of the series without any neurotoxicity and significant CNS depressant effect. Liver enzyme estimations (SGOT, SGPT, Alkaline phosphatase) of the compound also showed no significant change in the enzymes levels. Moreover, it caused 80% elevation of γ-amino butyric acid (GABA) levels in the whole mice brain, thus indicating that it could be a promising candidate in designing of a potent anticonvulsant drug.

  7. Design, synthesis, in vitro MAO-B inhibitory evaluation, and computational studies of some 6-nitrobenzothiazole-derived semicarbazones.

    PubMed

    Tripathi, Rati K P; Goshain, Omprakash; Ayyannan, Senthil Raja

    2013-03-01

    Monoamine oxidase B (MAO-B) is an important drug target for the treatment of neurological disorders. A series of 6-nitrobenzothiazole-derived semicarbazones were designed, synthesized, and evaluated as inhibitors of the rat brain MAO-B isoenzyme. Most of the compounds were found to be potent inhibitors of MAO-B, with IC(50) values in the nanomolar to micromolar range. Molecular docking studies were performed with AutoDock 4.2 to deduce the affinity and binding mode of these inhibitors toward the MAO-B active site. The free energies of binding (ΔG) and inhibition constants (K(i)) of the docked compounds were calculated by the Lamarckian genetic algorithm (LGA) of AutoDock 4.2. Good correlations between the calculated and experimental results were obtained. 1-[(4-Chlorophenyl)(phenyl)methylene]-4-(6-nitrobenzothiazol-2-yl)semicarbazide emerged as the lead MAO-B inhibitor, with top ranking in both the experimental MAO-B assay (IC(50): 0.004±0.001 μM) and in computational docking studies (K(i): 1.08 μM). Binding mode analysis of potent inhibitors suggests that these compounds are well accommodated by the MAO-B active site through stable hydrophobic and hydrogen bonding interactions. Interestingly, the 6-nitrobenzothiazole moiety is stabilized in the substrate cavity with the aryl or diaryl residues extending up into the entrance cavity of the active site. According to our results, docking experiments could be an interesting approach for predicting the activity and binding interactions of this class of semicarbazones against MAO-B. Thus, a binding site model consisting of three essential pharmacophoric features is proposed, and this can be used for the design of future MAO-B inhibitors.

  8. A new nano-scale manganese (II) coordination polymer constructed from semicarbazone Schiff base and dicyanamide ligands: Synthesis, crystal structure and DFT calculations

    NASA Astrophysics Data System (ADS)

    Farhadi, Saeed; Mahmoudi, Farzaneh; Simpson, Jim

    2016-03-01

    A new nano-structured Mn(II) coordination polymer [Mn(HL)(dca)(Cl)]n(1), [HL= Pyridine-2-carbaldehyde semicarbazone, dca= dicyanamide] has been synthesized by a sonochemical method and has been characterized by scanning electron microscopy, X-ray powder diffraction elemental analysis and IR spectroscopy. Single crystals of compound 1 was synthesized by slow evaporation method and was structurally characterised by single crystal X-ray diffraction. The single crystal structure shows one dimensional zig-zag chains with end-to-end dicyanamide-bridged ligand. A distorted octahedral geometry around the Mn2+centers was achieved by NNO atoms from HL, two nitrogen atoms of dicyanamide and one chlorine atom. Also for more details, the structure of 1, has been optimized by density functional theory (DFT calculations).

  9. Exploration of a Library of 3,4-(Methylenedioxy)aniline-Derived Semicarbazones as Dual Inhibitors of Monoamine Oxidase and Acetylcholinesterase: Design, Synthesis, and Evaluation.

    PubMed

    Tripathi, Rati K P; Rai, Gopal K; Ayyannan, Senthil R

    2016-06-06

    A library of 3,4-(methylenedioxy)aniline-derived semicarbazones was designed, synthesized, and evaluated as monoamine oxidase (MAO) and acetylcholinesterase (AChE) inhibitors for the treatment of neurodegenerative diseases. Most of the new compounds selectively inhibited MAO-B and AChE, with IC50 values in the micro- or nanomolar ranges. Compound 16, 1-(2,6-dichlorobenzylidene)-4-(benzo[1,3]dioxol-5-yl)semicarbazide presented a balanced multifunctional profile of MAO-A (IC50 =4.52±0.032 μm), MAO-B (IC50 =0.059±0.002 μm), and AChE (IC50 =0.0087±0.0002 μm) inhibition without neurotoxicity. Kinetic studies revealed that compound 16 exhibits competitive and reversible inhibition against MAO-A and MAO-B, and mixed-type inhibition against AChE. Molecular docking studies further revealed insight into the possible interactions within the enzyme-inhibitor complexes. The most active compounds were found to interact with the enzymes through hydrogen bonding and hydrophobic interactions. Additionally, in silico molecular properties and ADME properties of the synthesized compounds were calculated to explore their drug-like characteristics.

  10. Synthesis, spectroscopic (FT-IR, FT-Raman, UV and NMR) and computational studies on 3t-pentyl-2r,6c-diphenylpiperidin-4-one semicarbazone

    NASA Astrophysics Data System (ADS)

    Arockia doss, M.; Savithiri, S.; Rajarajan, G.; Thanikachalam, V.; Saleem, H.

    2015-09-01

    The structural and spectroscopic studies of 3t-pentyl-2r,6c-diphenylpiperidin-4-one semicarbazone (PDPOSC) were made by adopting B3LYP/HF levels theory using 6-311++G(d,p) basis set. The FT-IR and Raman spectra were recorded in solid phase, the fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. DFT method indicates that B3LYP is superior to HF method for molecular vibrational analysis. UV-vis spectrum of the compound was recorded in different solvents in the region of 200-800 nm and the electronic properties such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies were evaluated by time-dependent DFT (TD-DFT) approach. The polarizability and first order hyperpolarizability of the title molecule were calculated and interpreted. The hyperconjugative interaction energy (E(2)) and electron densities of donor (i) and acceptor (j) bonds were calculated using NBO analysis. In addition, MEP and atomic charges of carbon, nitrogen and oxygen were calculated using B3LYP/6-311++G(d,p) level theory. Moreover, thermodynamic properties of the title compound were calculated by B3LYP/HF, levels using 6-311++G(d,p) basis set. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results.

  11. Synthesis, spectroscopic (FT-IR, FT-Raman, UV and NMR) and computational studies on 3t-pentyl-2r,6c-diphenylpiperidin-4-one semicarbazone.

    PubMed

    Arockia doss, M; Savithiri, S; Rajarajan, G; Thanikachalam, V; Saleem, H

    2015-09-05

    The structural and spectroscopic studies of 3t-pentyl-2r,6c-diphenylpiperidin-4-one semicarbazone (PDPOSC) were made by adopting B3LYP/HF levels theory using 6-311++G(d,p) basis set. The FT-IR and Raman spectra were recorded in solid phase, the fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. DFT method indicates that B3LYP is superior to HF method for molecular vibrational analysis. UV-vis spectrum of the compound was recorded in different solvents in the region of 200-800 nm and the electronic properties such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies were evaluated by time-dependent DFT (TD-DFT) approach. The polarizability and first order hyperpolarizability of the title molecule were calculated and interpreted. The hyperconjugative interaction energy (E((2))) and electron densities of donor (i) and acceptor (j) bonds were calculated using NBO analysis. In addition, MEP and atomic charges of carbon, nitrogen and oxygen were calculated using B3LYP/6-311++G(d,p) level theory. Moreover, thermodynamic properties of the title compound were calculated by B3LYP/HF, levels using 6-311++G(d,p) basis set. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results.

  12. Design, synthesis and biological evaluation of novel 4-phenoxy-6,7-disubstituted quinolines possessing (thio)semicarbazones as c-Met kinase inhibitors.

    PubMed

    Zhai, Xin; Bao, Guanglong; Wang, Limei; Cheng, Mingke; Zhao, Meng; Zhao, Sijia; Zhou, Hongyang; Gong, Ping

    2016-03-15

    In continuing our efforts to identify small molecules able to inhibit c-Met kinase, three series of novel 6,7-disubstituted-4-phenoxyquinoline derivatives (23a-w, 26a-d and 30a-d) bearing (thio)semicarbazone scaffold were designed, synthesized and evaluated for their cytotoxicity. The biological data revealed that most compounds exhibited moderate-to-excellent activity against HT-29, MKN-45, A549 cancer cell lines and relative poor potency toward MDA-MB-231 cell as well as hardly any cytotoxicity in normal PBL cell. Eleven compounds were further examined for their inhibitory activity against c-Met kinase and three compounds (23h, 23n and 26a) demonstrated good inhibitory activity. This work resulted in the discovery of a potent c-Met inhibitor 23n, bearing 2-hydroxy-3-allylphenyl group at R(2) moiety, as a valuable lead molecule, which possessed remarkable cytotoxicity and high selectivity against A549 and HT-29 cell lines with IC50 values of 11 nM and 27 nM. Besides, it displayed excellent c-Met kinase inhibition on a single-digital nanomolar level (IC50=1.54 nM). Meanwhile, the results from preliminarily in vivo study reflected that compound 23n showed promising overall PK profiles, consistent with the efficacy in both MKN-45 and HT-29 tumor xenograft mice model. These results clearly indicated that compound 23n is a potent and highly selective c-Met inhibitor and its favorable in vitro and in vivo profiles warrant further investigation.

  13. Ligational behavior of thiosemicarbazone, semicarbazone and thiocarbohydrazone ligands towards VO(IV), Ce(III), Th(IV) and UO 2(VI) ions: Synthesis, structural characterization and biological studies

    NASA Astrophysics Data System (ADS)

    Shebl, M.; Seleem, H. S.; El-Shetary, B. A.

    2010-01-01

    Mono- and binuclear VO(IV), Ce(III), Th(IV) and UO 2(VI) complexes of thiosemicarbazone, semicarbazone and thiocarbohydrazone ligands derived from 4,6-diacetylresorcinol were synthesized. The structures of these complexes were elucidated by elemental analyses, IR, UV-vis, ESR, 1H NMR and mass spectra as well as conductivity and magnetic susceptibility measurements and thermal analyses. The thiosemicarbazone (H 4L 1) and the semicarbazone (H 4L 2) ligands behave as dibasic pentadentate ligands in case of VO(IV) and UO 2(VI) complexes, tribasic pentadentate in case of Ce(III) complexes and monobasic pentadentate in case of Th(IV) complexes. However, the thiocarbohydrazone ligand (H 3L 3) acts as a monobasic tridentate ligand in all complexes except the VO(IV) complex in which it acts as a dibasic tridentate ligand. The antibacterial and antifungal activities were also tested against Rhizobium bacteria and Fusarium-Oxysporium fungus. The metal complexes of H 4L 1 ligand showed a higher antibacterial effect than the free ligand while the other ligands (H 4L 2 and H 3L 3) showed a higher effect than their metal complexes. The antifungal effect of all metal complexes is lower than the free ligands.

  14. Semicarbazone EGA Inhibits Uptake of Diphtheria Toxin into Human Cells and Protects Cells from Intoxication

    PubMed Central

    Schnell, Leonie; Mittler, Ann-Katrin; Mattarei, Andrea; Tehran, Domenico Azarnia; Montecucco, Cesare; Barth, Holger

    2016-01-01

    Diphtheria toxin is a single-chain protein toxin that invades human cells by receptor-mediated endocytosis. In acidic endosomes, its translocation domain inserts into endosomal membranes and facilitates the transport of the catalytic domain (DTA) from endosomal lumen into the host cell cytosol. Here, DTA ADP-ribosylates elongation factor 2 inhibits protein synthesis and leads to cell death. The compound 4-bromobenzaldehyde N-(2,6-dimethylphenyl)semicarbazone (EGA) has been previously shown to protect cells from various bacterial protein toxins which deliver their enzymatic subunits from acidic endosomes to the cytosol, including Bacillus anthracis lethal toxin and the binary clostridial actin ADP-ribosylating toxins C2, iota and Clostridium difficile binary toxin (CDT). Here, we demonstrate that EGA also protects human cells from diphtheria toxin by inhibiting the pH-dependent translocation of DTA across cell membranes. The results suggest that EGA might serve for treatment and/or prevention of the severe disease diphtheria. PMID:27428999

  15. Discovery of N-(2,6-dimethylphenyl)-substituted semicarbazones as anticonvulsants: hybrid pharmacophore-based design.

    PubMed

    Yogeeswari, Perumal; Sriram, Dharmarajan; Thirumurugan, Rathinasabapathy; Raghavendran, Jegadeesan Vaigunda; Sudhan, Kannan; Pavana, Roheeth Kumar; Stables, James

    2005-10-06

    Epilepsy is the most common primary neurological disorder known. In the past decade, various aryl semicarbazones have been designed that were structurally dissimilar from many common anticonvulsants containing the dicarboximide function (CONRCO), which may contribute to toxic side effects. In the present work various N4-(2,6-dimethylphenyl) semicarbazones were designed as pharmacophore hybrids between the aryl semicarbazones and ameltolide. A three-dimensional four-point pharmacophore model was developed for anticonvulsants, and the title compounds were found to match with ralitoline. All of the compounds exhibited anticonvulsant activity in the maximal electroshock test when administered by both intraperitoneal and oral routes. Compound N1-(2,6-dimethylphenyl)-N4-(2-hydroxybenzaldehyde) semicarbazone (9) emerged as a prototype with wide spectrum anticonvulsant agent active in five models of seizure with no neurotoxicity and hepatotoxicity. Compound 9 increased the 4-aminobutyric acid (GABA) level by 118% and inhibited the GABA transaminase enzyme both in vitro and ex vivo.

  16. 4-(Diphenyl­amino)­benzaldehyde 4-phenyl­thio­semicarbazone

    PubMed Central

    Mendoza-Meroño, Rafael; Menéndez-Taboada, Laura; García-Granda, Santiago

    2012-01-01

    The title mol­ecule, C26H22N4S, is composed of three main parts, viz. a triphenyl­amine group is connected to a phenyl ring by a thio­semicarbazone moiety. The C= N double bond has an E conformation. The crystal packing is dominated by strong hydrogen bonds through the thio­semicarbazone moiety, with pairs of N—H⋯S hydrogen bonds linking the mol­ecules to form inversion dimers with an R 2 2(8) ring motif. An intra­molecular N—H⋯N hydrogen bond is also present, generating an S(5) ring motif. Although the structure contains four phenyl rings, π–π stacking inter­actions are not formed between them, probably due to the conformation adopted by the triphenyl­amine group. However, a weak π–π stacking inter­action is observed between the phenyl ring and the delocalized thio­semicarbazone moiety. PMID:22904859

  17. Structure and spectral properties of dinuclear zinc complex containing semicarbazonate ligands

    NASA Astrophysics Data System (ADS)

    Jing-Lin, Wang; Jiao, Feng; Mei-Ping, Xu; Bin-Sheng, Yang

    2011-04-01

    The dinuclear Zn 2+ complex [Zn(HSSC)OAc] 2·2DMF (H 2SSC = salicylaldehyde semicarbazone; HOAc = acetic acid; DMF = N,N-dimethylfomamide) was prepared and structurally characterized by single crystal X-ray. The basic structural unit of the complex is a dinuclear complex [Zn(HSSC)OAc] 2 in which the semicarbazone ligand adopts the phenol-imine form. The deprotonated phenol group forms a one-atom bridge between the two zinc centers, and both of the zinc centers are five-coordinated. The local coordination environment of Zn 2+ can be approximately considered as square pyramidal. UV spectral studies show that the H 2SSC provides strong binding of Zn 2+ in a 1:1 ratio in solution. The conditional binding constant of the complex is lg KZn-L = 12.89 ± 0.76 in 0.05 M Tris-HCl buffer at pH 7.4. The H 2SSC exhibits an enhanced fluorescence effect by the addition of Zn 2+, and affords an excellent selectivity for Zn 2+ under physiological conditions.

  18. Four transition metal complexes with a semicarbazone ligand bearing pyrazine unit

    NASA Astrophysics Data System (ADS)

    Chen, Hong; Ma, Xiu-qin; Lv, Yan-yun; Jia, Lei; Xu, Jun; Wang, Yuan; Ge, Zhi-jun

    2016-04-01

    Four new complexes based on L (where L = 3-ethyl-2-acetylpyrazine semicarbazone), namely [CoL2]Cl2·0.5H2O (1), [CoL2](NO3)2 (2), [CdL(H2O)2(NO3)](NO3)·H2O (3) and [CuL(CH3OH)Cl2]·[CuLCl2] (4) have been synthesized and characterized by X-ray diffraction analyses. The results show that the semicarbazone acts as a tridentate neutral ligand in all complexes. Each of complex 1 and 2 reveals a distorted octahedral geometry around the metal ion provided by two units of the ligand, while the ratio of the ligand and metal is 1:1 in complexes 3 and 4. The effect of complexes 1-4 on cell proliferation, apoptosis of human pancreatic cancer (Patu8988), human gastric cancer (SGC7901) and human hepatic cancer (SMMC7721) cell lines have been detected by MTT assay, Annexin V/PI double staining flow cytometry and TUNEL assay. The results show that complexes 1-4 can inhibit cell proliferation of Patu8988, SGC7901 and SMMC7721 cells, significantly higher than the effect of the ligand. However, the complex 4 reveals higher apoptosis rate, and displays up-regulated expression level of caspase 3, detected by western blotting, which also indicates the complex 4 can induce caspase-dependent cell apoptosis in SMMC7721.

  19. Identification of Semicarbazones, Thiosemicarbazones and Triazine Nitriles as Inhibitors of Leishmania mexicana Cysteine Protease CPB

    PubMed Central

    Schröder, Jörg; Noack, Sandra; Marhöfer, Richard J.; Mottram, Jeremy C.; Coombs, Graham H.; Selzer, Paul M.

    2013-01-01

    Cysteine proteases of the papain superfamily are present in nearly all eukaryotes. They play pivotal roles in the biology of parasites and inhibition of cysteine proteases is emerging as an important strategy to combat parasitic diseases such as sleeping sickness, Chagas’ disease and leishmaniasis. Homology modeling of the mature Leishmania mexicana cysteine protease CPB2.8 suggested that it differs significantly from bovine cathepsin B and thus could be a good drug target. High throughput screening of a compound library against this enzyme and bovine cathepsin B in a counter assay identified four novel inhibitors, containing the warhead-types semicarbazone, thiosemicarbazone and triazine nitrile, that can be used as leads for antiparasite drug design. Covalent docking experiments confirmed the SARs of these lead compounds in an effort to understand the structural elements required for specific inhibition of CPB2.8. This study has provided starting points for the design of selective and highly potent inhibitors of L. mexicana cysteine protease CPB that may also have useful efficacy against other important cysteine proteases. PMID:24146999

  20. Crystal structures of crotonaldehyde semicarbazone and crotonaldehyde thiosemicarbazone from X-ray powder diffraction data

    PubMed Central

    Arfan, Atef; Rukiah, Mwaffak

    2015-01-01

    Crotonaldehyde semicarbazone {systematic name: (E)-2-[(E)-but-2-en-1-yl­idene]hydrazinecarboxamide}, C5H9N3O, (I), and crotonaldehyde thio­semi­carba­zone {systematic name: (E)-2-[(E)-but-2-en-1-yldene]hydra­zinecarbo­­thio­amide}, C5H9N3S, (II), show the same E conformation around the imine C=N bond. Compounds (I) and (II) were obtained by the condensation of crotonaldehyde with semicarbazide hydro­chloride and thio­semicarbazide, respectively. Each mol­ecule has an intra­molecular N—H⋯N hydrogen bond, which generates an S(5) ring. In (I), the crotonaldehyde fragment is twisted by 2.59 (5)° from the semicarbazide mean plane, while in (II) the corresponding angle (with the thio­semicarbazide mean plane) is 9.12 (5)°. The crystal packing is different in the two compounds: in (I) inter­molecular N—H⋯O hydrogen bonds link the mol­ecules into layers parallel to the bc plane, while weak inter­molecular N—H⋯S hydrogen bonds in (II) link the mol­ecules into chains propagating in [110]. PMID:25878810

  1. Spectroscopic evaluation of Co(II), Ni(II) and Cu(II) complexes derived from thiosemicarbazone and semicarbazone.

    PubMed

    Chandra, Sulekh; Kumar, Anil

    2007-12-31

    Co(II), Ni(II) and Cu(II) complexes were synthesized with thiosemicarbazone (L(1)) and semicarbazone (L(2)) derived from 2-acetyl furan. These complexes were characterized by elemental analysis, molar conductance, magnetic moment, mass, IR, electronic and EPR spectral studies. The molar conductance measurement of the complexes in DMSO corresponds to non-electrolytic nature. All the complexes are of high-spin type. On the basis of different spectral studies six coordinated geometry may be assigned for all the complexes except Co(L)(2)(SO(4)) and Cu(L)(2)(SO(4)) [where L=L(1) and L(2)] which are of five coordinated square pyramidal geometry.

  2. Biological effects of a complex of vanadium(V) with salicylaldehyde semicarbazone in osteoblasts in culture: mechanism of action.

    PubMed

    Rivadeneira, Josefina; Barrio, Daniel A; Arrambide, Gabriel; Gambino, Dinorah; Bruzzone, Liliana; Etcheverry, Susana B

    2009-04-01

    Vanadium compounds display important pharmacological actions in vivo and in vitro systems. Semicarbazones are versatile ligands with therapeutic effects. Herein, we report the effects of V(V)O(2)(salicylaldehydesemicarbazone) (V(V)-Salsem) on two osteoblast cell lines in culture (MC3T3-E1 and UMR106). V(V)-Salsem inhibited cell proliferation in a dose response manner. At 100muM, the complex caused an inhibition of ca. 48% and 38% for the normal and the tumoral osteoblasts, respectively (p<0.001). This inhibition could be partially reversed to 35% and 28% by NAC (N-acetylcysteine) and a mixture of vitamins E and C. Changes in cell proliferation correlated with morphological alterations and the disruption of actin cytoskeleton fibers. The complex also enhanced the level of ROS (reactive oxygen species) up to ca. 100% over basal in both cell lines. Activation of ERK signalling cascade was also observed. These events led to apoptosis (up to 44% in MC3T3-E1 and 33% in UMR106 cells). Scavengers of ROS and inhibitors of ERK cascade allowed to elucidate the mechanisms involved in the cytotoxicity. In conclusion, V(V)-Salsem displayed cytotoxic effects on osteoblasts in culture through the production of free radicals and the activation of ERK cascade. These mechanisms triggered the apoptotic events that conveyed to cell death.

  3. Spectral studies on Co(II), Ni(II) and Cu(II) complexes with thiosemicarbazone (L1) and semicarbazone (L2) derived from 2-acetyl furan.

    PubMed

    Chandra, Sulekh; Kumar, Anil

    2007-04-01

    Co(II), Ni(II) and Cu(II) complexes are synthesized with thiosemicarbazone (L1) and semicarbazone (L2) derived from 2-acetyl furan. These complexes are characterized by elemental analysis, molar conductance, magnetic susceptibility measurements, mass, IR, electronic and EPR spectral studies. The molar conductance measurements of the complexes in DMSO correspond to non-electrolytic nature except Ni(L)2(NO3)2, which is 1:2 electrolyte. All the complexes are of high-spin type. On the basis of spectral studies an octahedral geometry may be assigned for Co(II) and Ni(II) complexes except nitrato complexes of Ni(II) which is of tetrahedral geometry, whereas tetragonal geometry for Cu(II) complexes.

  4. Metal complexes of a pentadentate N2O3bis(semicarbazone) Schiff-base. A case study of structure-spectroscopy correlation

    NASA Astrophysics Data System (ADS)

    Inoue, Mayara Hissami; Ribeiro, Ronny Rocha; Sabino, José Ricardo; Nunes, Fábio Souza

    2016-07-01

    Schiff condensation of 2,6-diformyl 4-methylphenol with semicarbazide hydrochloride in 1:2 molar ratio produces the bis(semicarbazone) ligand, herein called H3L. A comprehensive spectroscopic analysis of the compound was performed by 1H and 13C NMR, FTIR and electronic spectroscopies. Assignments to the UV-vis spectrum of H3L were supported by semi-empirical quantum mechanics ZINDO/S calculations. The ligand H3L forms monoclinic crystals in the space group P21/c and its structure is stabilized by classic hydrogen bonds with propanone molecules. It promptly reacts with first row metal ions to produce the following coordination compounds: [Co2(L)(μ-NO3)]·DMF, [Ni2(H2L)(μ-CH3COO)(CH3COO)2]·2H2O, [Cu2(L)(μ-NO3)(H2O)2]·H2O, [Cu2(L)(μ-CH3COO)(H2O)2]·H2O and [Cu2(H2L)(μ-Cl)Cl2]·3H2O, that have different compositions, depending on the degree of deprotonation of the ligand upon coordination. Electronic and EPR spectroscopies as well as effective magnetic moment measurements of the complexes were used in an attempt to better understand their mode of coordination, the microsymmetry around the metal ions and magnetic properties.

  5. Crystal structures of copper(II) nitrate, copper(II) chloride, and copper(II) perchlorate complexes with 2-formylpyridine semicarbazone

    SciTech Connect

    Chumakov, Yu. M.; Tsapkov, V. I.; Antosyak, B. Ya.; Bairac, N. N.; Simonov, Yu. A.; Bocelli, G.; Pahontu, E.; Gulea, A. P.

    2009-05-15

    Compounds dinitrato(2-formylpyridinesemicarbazone)copper (I), dichloro(2-formylpyridinesemicarbazone) copper hemihydrate (II), and bis(2-formylpyridinesemicarbazone)copper(2+) perchlorate hydrate (III) are synthesized and their crystal structures are determined. In compounds I-III, the neutral 2-formylpyridine semicarbazone molecule (L) is tridentately attached to the copper atom via the N,N,O set of donor atoms. In compounds I and II, the Cu: L ratio is equal to 1: 1, whereas, in III, it is 1: 2. In complex I, the coordination sphere of the copper atom includes two nitrate ions with different structural functions in addition to the L ligand. The structure is built as a one-dimensional polymer in which the NO{sub 3} bidentate group fulfills a bridging function. The coordination polyhedron of the copper(2+) atom can be considered a distorted tetragonal bipyramid (4 + 1 + 1). Compound II has an ionic structure in which the main element is the [CuLCl{sub 2} . Cu(H{sub 2}O)LCl]{sup +} dimer. In the dimer, the copper atoms are linked via one of the {mu}{sub 2}-bridging chlorine atoms. The coordination polyhedra of the central atoms of the Cu(H{sub 2})LCl and CuLCl{sub 2} complex fragments are tetragonal bipyramid and tetragonal pyramid, respectively. In compound III, the copper atom is octahedrally surrounded by two L ligands in the mer configuration.

  6. Metal complexes of a pentadentate N2O3bis(semicarbazone) Schiff-base. A case study of structure-spectroscopy correlation.

    PubMed

    Inoue, Mayara Hissami; Ribeiro, Ronny Rocha; Sabino, José Ricardo; Nunes, Fábio Souza

    2016-07-05

    Schiff condensation of 2,6-diformyl 4-methylphenol with semicarbazide hydrochloride in 1:2 molar ratio produces the bis(semicarbazone) ligand, herein called H3L. A comprehensive spectroscopic analysis of the compound was performed by (1)H and (13)C NMR, FTIR and electronic spectroscopies. Assignments to the UV-vis spectrum of H3L were supported by semi-empirical quantum mechanics ZINDO/S calculations. The ligand H3L forms monoclinic crystals in the space group P21/c and its structure is stabilized by classic hydrogen bonds with propanone molecules. It promptly reacts with first row metal ions to produce the following coordination compounds: [Co2(L)(μ-NO3)]·DMF, [Ni2(H2L)(μ-CH3COO)(CH3COO)2]·2H2O, [Cu2(L)(μ-NO3)(H2O)2]·H2O, [Cu2(L)(μ-CH3COO)(H2O)2]·H2O and [Cu2(H2L)(μ-Cl)Cl2]·3H2O, that have different compositions, depending on the degree of deprotonation of the ligand upon coordination. Electronic and EPR spectroscopies as well as effective magnetic moment measurements of the complexes were used in an attempt to better understand their mode of coordination, the microsymmetry around the metal ions and magnetic properties.

  7. Downregulation of oncogenic RAS and c-Myc expression in MOLT-4 leukaemia cells by a salicylaldehyde semicarbazone copper(II) complex.

    PubMed

    Goh, Yan-Yih; Yan, Yaw-Kai; Tan, Nguan Soon; Goh, Su-Ann; Li, Shang; Teoh, You-Chuan; Lee, Peter P F

    2016-11-14

    Copper complexes with potent anti-tumor effect have been extensively developed. Most investigations of their modes of action focused on the biomolecular targets but not the signal transduction between target binding and cell death. We have previously shown that the cytotoxic complex pyridine(2,4-dihydroxybenzaldehyde dibenzyl semicarbazone)copper(II) (complex 1) shows selective binding to human telomeric G-quadruplex DNA over double-stranded DNA in vitro. Herein, we elucidate the mechanism of action by which complex 1 induces apoptosis in MOLT-4 cells. Complex 1 accumulates in the nuclei and differentially downregulates the expression of c-Myc, c-Kit and KRAS oncogenes. Chemical affinity capture assay results show that the complex is associated with c-Myc and KRAS quadruplex sequences in MOLT-4 cells. We further showed that the reduction in Ras protein expression resulted in attenuated MEK-ERK and PI3K-Akt signalling activities, leading to the activation of caspase-dependent apoptosis. Notably, complex 1 increased the sensitivity of MOLT-4 cells to cisplatin and vice versa. Overall, we demonstrated that complex 1 induces apoptosis, at least in part, by suppressing KRAS, c-Kit and c-Myc oncogene expression and the pro-survival MEK-ERK and PI3K-Akt signalling pathways.

  8. Downregulation of oncogenic RAS and c-Myc expression in MOLT-4 leukaemia cells by a salicylaldehyde semicarbazone copper(II) complex

    PubMed Central

    Goh, Yan-Yih; Yan, Yaw-Kai; Tan, Nguan Soon; Goh, Su-Ann; Li, Shang; Teoh, You-Chuan; Lee, Peter P. F.

    2016-01-01

    Copper complexes with potent anti-tumor effect have been extensively developed. Most investigations of their modes of action focused on the biomolecular targets but not the signal transduction between target binding and cell death. We have previously shown that the cytotoxic complex pyridine(2,4-dihydroxybenzaldehyde dibenzyl semicarbazone)copper(II) (complex 1) shows selective binding to human telomeric G-quadruplex DNA over double-stranded DNA in vitro. Herein, we elucidate the mechanism of action by which complex 1 induces apoptosis in MOLT-4 cells. Complex 1 accumulates in the nuclei and differentially downregulates the expression of c-Myc, c-Kit and KRAS oncogenes. Chemical affinity capture assay results show that the complex is associated with c-Myc and KRAS quadruplex sequences in MOLT-4 cells. We further showed that the reduction in Ras protein expression resulted in attenuated MEK-ERK and PI3K-Akt signalling activities, leading to the activation of caspase-dependent apoptosis. Notably, complex 1 increased the sensitivity of MOLT-4 cells to cisplatin and vice versa. Overall, we demonstrated that complex 1 induces apoptosis, at least in part, by suppressing KRAS, c-Kit and c-Myc oncogene expression and the pro-survival MEK-ERK and PI3K-Akt signalling pathways. PMID:27841290

  9. Synthesis and alkylation of aza-glycinyl dipeptide building blocks.

    PubMed

    Garcia-Ramos, Yesica; Lubell, William D

    2013-12-01

    Aza-glycinyl dipeptides are useful building blocks for the synthesis of a diverse array of azapeptides. The construction of the aza-glycine residue is however challenging, because of the potential for side reactions, such as those leading to formation of oxadiazalone, hydantoin and symmetric urea by-products. Employing N,N'-disuccinimidyl carbonate to activate benzophenone hydrazone, we have developed a more efficient approach for the synthesis of aza-glycinyl dipeptides. Alkylation of the semicarbazone of the resulting protected aza-glycinyl dipeptides using tetraethylammonium hydroxide and propargyl bromide provided an efficient entry into the aza-propargylglycinyl peptide building blocks, which have served previously in various reactions including Sonogashira cross-couplings, dipolar cycloadditions and intramolecular exo-dig cycloadditions to furnish a variety of azapeptide building blocks.

  10. A 119Sn Mössbauer Study of Tin(IV) Complexes of 2- and 4-Benzoylpyridine Thiosemicarbazone and 4-Benzoylpyridine Semicarbazone

    NASA Astrophysics Data System (ADS)

    Pérez-Rebolledo, Anayive; Ardisson, José D.; de Lima, Geraldo M.; Macedo, Waldemar A. A.; Beraldo, Heloisa

    2005-06-01

    A 119Sn Mössbauer study was carried out of tin(IV) complexes with 2-benzoylpyridine thiosemicarbazone (H2Bz4DH) and its N(4)-methyl (H2Bz4M) and N(4)-phenyl (H2Bz4Ph) derivatives: [Sn(2Bz4DH)Cl3] (1), [Sn(2Bz4DH)PhCl2] (2), [Sn(2Bz4M)Cl3] (3), [H22Bz4M]2[Ph2SnCl4] (4), [Sn(2Bz4Ph)PhCl2] (5), [Sn(2Bz4Ph)Ph2Cl] (6), in which H2Bz4R stands for the neutral ligand and 2Bz4R stands for the anionic thiosemicarbazone. In addition, 119Sn Mössbauer studies of the tin(IV) complexes [Sn(H4Bz4DH)2Cl4H2O] (7), [Sn(H4BzPS)2Cl4H2O] (8) with 4-benzoylpyridine thiosemicarbazone (H4Bz4DH) and the correspondent semicarbazone (H4BzPS) were performed. The isomer shifts decrease upon coordination due to the variation in the percentage of s character as tin changes from approximately sp3 hybridization in the tin salts to sp3d2 in the octahedral or sp3d3 in the heptahedral complexes. The Mössbauer parameters of compound (4) showed the existence of two tin(IV) sites, which have been attributed to the presence of the cis and trans isomers.

  11. A new nanohybrid material constructed from Keggin-type polyoxometalate and Cd(II) semicarbazone Schiff base complex with excellent adsorption properties for the removal of cationic dye pollutants

    NASA Astrophysics Data System (ADS)

    Farhadi, Saeed; Amini, Mostafa M.; Dusek, Michal; Kucerakova, Monika; Mahmoudi, Farzaneh

    2017-02-01

    A novel nanohybrid material containing a Cd(II) semicarbazone Schiff base complex and phosphomolybdic acid, [Cd(H2L+)6][H2L]+4[PMo12O40]4·18CH3OH·4H2O (1), [HL = pyridine-2-carbaldehyde semicarbazone] was prepared by a simple sonochemical route and characterized by 1HNMR, 13CNMR, FT-IR, UV-vis, PXRD, FESEM, TG-DTA and BET-BJH surface area analysis. Also the single crystal 1, was characterized by single-crystal X-ray diffraction analysis. It crystallizes in the triclinic system with space group P-1 and is assembled into 3D supramolecular structure via hydrogen intermolecular interactions. The nanohybrid 1 was tested for the adsorption and removal of organic dyes such as methylene blue (MB), Rhodamine B (RhB) and methyl orange (MO) from aqueous solutions. The effects of parameters such as the dosage of adsorbent, the initial concentration and pH of dye solution were investigated on the removal efficiency of methylene blue. The nanohybrid 1 exhibited excellent adsorption ability towards cationic dyes. Moreover, it could be easily separated from the reaction solution and recycled up to three times without significant loss of adsorption activity.

  12. Synthesis, characterization, DNA interaction, antioxidant and anticancer activity of new ruthenium(II) complexes of thiosemicarbazone/semicarbazone bearing 9,10-phenanthrenequinone.

    PubMed

    Anitha, Panneerselvam; Chitrapriya, Nataraj; Jang, Yoon Jung; Viswanathamurthi, Periasamy

    2013-12-05

    A new series of octahedral ruthenium(II) complexes supported by tridentate ligands derived from phenanthrenequinone and derivatives of thiosemicarbazide/semicarbazide and other co-ligands have been synthesized and characterized. DNA binding experiments indicated that ruthenium(II) complexes can interact with DNA through non-intercalation and the apparent binding constant value (Kb) of [RuCl(CO)(PPh₃)(L₃)] (3) at room temperature was calculated to be 2.27 × 10(3)M(-1). The DNA cleavage studies showed that the complexes have better cleavage of pBR 322 DNA. Antioxidative activity proved that the complexes have significant radical scavenging activity against free radicals. Cytotoxic activities showed that the ruthenium(II) complexes exhibited more effective cytotoxic activity against selected cancer cells.

  13. Design, structural and spectroscopic elucidation of new nitroaromatic carboxylic acids and semicarbazones for the in vitro screening of anti-leishmanial activity

    NASA Astrophysics Data System (ADS)

    Dias, L. C.; de Lima, G. M.; Pinheiro, C. B.; Rodrigues, B. L.; Donnici, C. L.; Fujiwara, R. T.; Bartholomeu, D. C.; Ferreira, R. A.; Ferreira, S. R.; Mendes, T. A. O.; da Silva, J. G.; Alves, M. R. A.

    2015-01-01

    In this paper we report the synthesis and characterization of four new nitroaromatic compounds, 2-{6-nitrobenzo[1,3]dioxol-5-(methyleneamino)}benzoic acid (1), 2-{[5-(2-nitrophenyl)furan-2-yl]methylene-amino}benzoic acid (2), 2-{(6-nitrobenzo[1,3]dioxol-5-yl)methylene}hydrazinecarboxamide (3) and 2-{[5-(2-nitrophenyl)furan-2-yl]methylene}hydrazinecarboxamide (4). Compounds (1)-(4) have been authenticated by infrared and NMR spectroscopy, and the structure of (1), (2) and (4) have been determined by X-ray diffraction. In addition, the in vitro ability of compounds (1)-(4) to inhibit the growth of Leishmania infantum has been evaluated. Comparisons of the redox potential of the compounds and leishmanicidal activity indicate that the presence of the electroactive nitro group is important for the biological activity. The inhibition activity of compound (3) is comparable to that of the reference drug, SbCl3. Considering the important side effects and the low efficiency of SbCl3 in the case of resistance, compound (3) deserves further attention as a promising anti-leishmanicidal drug for veterinary use.

  14. Structure-activity relationships of GHRP-6 azapeptide ligands of the CD36 scavenger receptor by solid-phase submonomer azapeptide synthesis.

    PubMed

    Sabatino, David; Proulx, Caroline; Pohankova, Petra; Ong, Huy; Lubell, William D

    2011-08-17

    The cluster of differentiation 36 (CD36) class B scavenger receptor binds a variety of biologically endogenous ligands in addition to synthetic peptides (i.e., growth hormone-releasing peptides, GHRPs), which modulate biological function related to anti-angiogenic and anti-atherosclerotic activities. Affinity labeling had previously shown that GHRP-6 analogues such as hexarelin, [2-Me-W(2)]GHRP-6 (1), bind to the lysine-rich domain of the CD36 receptor. Moreover, the azapeptide analogue [aza-F(4)]GHRP-6, 2, exhibited a characteristic β-turn conformation as described by CD and NMR spectroscopy and a slightly higher CD36 binding affinity relative to hexarelin (1.34 and 2.37 μM, respectively), suggesting receptor binding was mediated by the conformation and the aromatic residues of these peptide sequences. Ligand-receptor binding interactions were thus explored using azapeptides to examine influences of side-chain diversity and backbone conformation. In particular, considering that aromatic cation interactions may contribute to binding affinity, we have explored the potential of introducing salt bridges to furnish GHRP-6 azapeptide ligands of the CD36 receptor. Fifteen aza-glutamic acid analogues related to 2 were prepared by submonomer solid-phase synthesis. The azapeptide side chains were installed by novel approaches featuring alkylation of resin-bound semicarbazone with Michael acceptors and activated allylic acetates in the presence of phosphazene base (BTPP). Moreover, certain Michael adducts underwent intramolecular cyclization during semicarbazone deprotection, leading to novel pyrrazoline and aza-pyroglutamate N-terminal residues. Structural studies indicated that contingent on sequence the [aza-Glu]GHRP-6 analogues exhibited CD spectra characteristic of random coil, polyproline type II and β-turn secondary structures in aqueous media. In covalent competition binding studies with the GHRP-6 prototype hexarelin bearing a radiotracer, certain [aza-Glu]GHRP-6

  15. Microwave assisted synthesis, spectroscopic, electrochemical and DNA cleavage studies of lanthanide(III) complexes with coumarin based imines.

    PubMed

    Kapoor, Puja; Fahmi, Nighat; Singh, R V

    2011-12-01

    The present work stems from our interest in the synthesis, characterization and biological evaluation of lanthanide(III) complexes of a class of coumarin based imines which have been prepared by the interaction of hydrated lanthanide(III) chloride with the sodium salts of 3-acetylcoumarin thiosemicarbazone (ACTSZH) and 3-acetylcoumarin semicarbazone (ACSZH) in 1:3 molar ratio using thermal as well as microwave method. Characterization of the ligands as well as the metal complexes have been carried out by elemental analysis, melting point determinations, molecular weight determinations, magnetic moment, molar conductance, IR, (1)H NMR, (13)C NMR, electronic, EPR, X-ray powder diffraction and mass spectral studies. Spectral studies confirm ligands to be monofunctional bidentate and octahedral environment around metal ions. The redox behavior of one of the synthesized metal complex was investigated by cyclic voltammetry. Further, free ligands and their metal complexes have been screened for their antimicrobial as well as DNA cleavage activity. The results of these findings have been presented and discussed.

  16. Synthesis, Characterization, In Vitro and In Vivo Screening of Unsymmetrical Borole Complexes of 2-Hydroxy-N-Phenylbenzamide and its Derivatives

    PubMed Central

    Pandey, Taruna

    2000-01-01

    Biochemical aspects, synthesis and characterization of some boron complexes of 2-hydroxy-N-phenylbenzamide (HOPhBenz) and its semicarbazone (HOPhBenz.SCZH) and thiosemicarbazone (HOPhBenz.TSCZH) are described. These derivatives were prepared by the reactions of 2-isopropoxy-4-methyl-1,3,2-dioxaborolane, and 2-isopropoxy-4-methyl-1,3,2-dioxaborinane with 2-hydroxy-N-phenylbenzamide, 1-[(2-hydroxyphenyl)-1-N-phenylamino]hydrazinecarboxamide (HOPhBenz.SCZH), and 1-[(2-hydroxyphenyl)-1-N-phenylamino]hydrazinecarbothioamide(HOPhBenz.TSCZH) in a 1:1 molar ratio. In order to assess the increase of the inhibitor potency, (HOPhBenz), (HOPhBenz.SCZH), (HOPhBenz.TSCZH) and their boron complexes have been tested in vitro against a number of pathogenic fungi and bacteria at different concentrations and were found to possess remarkable fungicidal and bactericidal properties. The testicular sperm density, testicular sperm morphology, sperm motility, density of cauda epididymal spermatozoa and fertility in mating trials and biochemical parameters of reproductive organs are discussed. PMID:18475918

  17. Ammonia synthesis

    SciTech Connect

    Mandelik, B.G.; Cassata, J.R.; Katy, P.J.S.; Van Dijk, C.P.

    1986-02-04

    In a process for producing ammonia in a synthesis loop in which fresh synthesis gas containing hydrogen, nitrogen and, lesser amounts of argon and methane is combined with a hydrogen enriched recycle gas to provide combined synthesis gas, the combined synthesis is introduced to and reacted over ammonia synthesis catalyst under synthesis conditions to provide converted gas containing ammonia, hydrogen, and nitrogen. The ammonia is recovered from the converted gas to provide recycle gas, and a purge stream is removed from the synthesis loop. A hydrogen-rich gas is recovered from the purge stream, and the hydrogen-rich gas is combined with the recycle gas to provide the hydrogen enriched gas. The improvement described in this patent consists of (a) providing the fresh synthesis gas at a hydrogen to nitrogen molar ratio between 1.7 and 2.5 and providing the hydrogen enriched recycle gas at a hydrogen to nitrogen molar ratio between 0.5 and 1.7 to provide the combined synthesis gas at a hydrogen to nitrogen molar ratio between 0.8 and 1.8. The volumetric flow rate ratio of the hydrogen enriched recycle gas to the fresh synthesis gas is between 2.2 and 3.7; and (b) introducing the combined synthesis gas from step (a) to an ammonia synthesis catalyst at a temperature between 315/sup 0/C. and 400/sup 0/C. and a pressure between 50 kg/cm/sup 2/ and 150 kg/cm/sup 2/.

  18. Synthesis of 2-(β-D-glucopyranosylamino)-5-substituted-1,3,4-oxadiazoles for inhibition of glycogen phosphorylase.

    PubMed

    Tóth, Marietta; Szőcs, Béla; Kaszás, Tímea; Docsa, Tibor; Gergely, Pál; Somsák, László

    2013-11-15

    Aromatic aldehyde 4-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)semicarbazones were synthesized by the addition of different hydrazones onto O-peracetylated β-d-glucopyranosyl isocyanate. Oxidative transformations of these precursors gave O-protected 2-(β-d-glucopyranosylamino)-5-substituted-1,3,4-oxadiazoles. Removal of the O-acetyl protecting groups under Zemplén conditions gave test compounds to show low micromolar inhibition against rabbit muscle glycogen phosphorylase b. Best inhibitors of these series were 4-(β-d-glucopyranosyl)semicarbazones of 4-nitrobenzaldehyde (Ki=4.5μM), 2-naphthaldehyde (Ki=5.5μM) and 2-(β-d-glucopyranosylamino)-5-(4-methylphenyl)-1,3,4-oxadiazole (Ki=12μM).

  19. Total Synthesis of (-)-Conolutinine.

    PubMed

    Feng, Xiangyang; Jiang, Guangde; Xia, Zilei; Hu, Jiadong; Wan, Xiaolong; Gao, Jin-Ming; Lai, Yisheng; Xie, Weiqing

    2015-09-18

    The first enantioselective synthesis of (-)-conolutinine was achieved in 10 steps. The synthesis featured a catalytic asymmetric bromocyclization of tryptamine to forge the tricycle intermediate. Hydration of an alkene catalyzed by Co(acac)2 was also employed as a key step to diastereoselectively introduce the tertiary alcohol moiety. The absolute configuration of (-)-conolutinine was established to be (2S,5aS,8aS,13aR) based on this asymmetric total synthesis.

  20. Total synthesis of haliclamide.

    PubMed

    Gahalawat, Suraksha; Pandey, Satyendra Kumar

    2016-10-04

    A stereoselective approach for the synthesis of haliclamide 1, a marine natural product, has been developed. The notable features of our synthesis include MacMillan cross aldol, Mitsunobu inversion, Yamaguchi-Hirao alkylation, Steglich esterification and macrolactamization reactions and the Corey-Fuchs protocol as the key steps.

  1. Parallelizing quantum circuit synthesis

    NASA Astrophysics Data System (ADS)

    Di Matteo, Olivia; Mosca, Michele

    2016-03-01

    Quantum circuit synthesis is the process in which an arbitrary unitary operation is decomposed into a sequence of gates from a universal set, typically one which a quantum computer can implement both efficiently and fault-tolerantly. As physical implementations of quantum computers improve, the need is growing for tools that can effectively synthesize components of the circuits and algorithms they will run. Existing algorithms for exact, multi-qubit circuit synthesis scale exponentially in the number of qubits and circuit depth, leaving synthesis intractable for circuits on more than a handful of qubits. Even modest improvements in circuit synthesis procedures may lead to significant advances, pushing forward the boundaries of not only the size of solvable circuit synthesis problems, but also in what can be realized physically as a result of having more efficient circuits. We present a method for quantum circuit synthesis using deterministic walks. Also termed pseudorandom walks, these are walks in which once a starting point is chosen, its path is completely determined. We apply our method to construct a parallel framework for circuit synthesis, and implement one such version performing optimal T-count synthesis over the Clifford+T gate set. We use our software to present examples where parallelization offers a significant speedup on the runtime, as well as directly confirm that the 4-qubit 1-bit full adder has optimal T-count 7 and T-depth 3.

  2. Automatic Program Synthesis Reports.

    ERIC Educational Resources Information Center

    Biermann, A. W.; And Others

    Some of the major results of future goals of an automatic program synthesis project are described in the two papers that comprise this document. The first paper gives a detailed algorithm for synthesizing a computer program from a trace of its behavior. Since the algorithm involves a search, the length of time required to do the synthesis of…

  3. Synthesis of Psychrophilin E.

    PubMed

    Ngen, Sarah T Y; Kaur, Harveen; Hume, Paul A; Furkert, Daniel P; Brimble, Margaret A

    2016-09-02

    The first total synthesis of psychrophilin E, a potent antiproliferative cyclic tripeptide isolated from Aspergillus versicolor ZLN-60, is reported herein. Key features of the synthesis include the installation of an amide bond between the indole-nitrogen of tryptophan and an anthranilic acid residue, and a high yielding macrolactamization of the linear tripeptide to the desired macrocycle.

  4. Chemical Synthesis of Cycloparaphenylenes

    NASA Astrophysics Data System (ADS)

    Segawa, Yasutomo; Yagi, Akiko; Itami, Kenichiro

    2017-01-01

    Cycloparaphenylenes and analogues thereof are substances having excellent structural and electronic properties due to radial π-conjugation modes and porous structures. Since they are partial structures of carbon nanotubes, they have also attracted attention as a template for carbon nanotube synthesis. In this chapter, we introduce a series of research on the synthesis of cycloparaphenylenes and their analogues.

  5. Chemical Synthesis of Proteins

    PubMed Central

    Nilsson, Bradley L.; Soellner, Matthew B.; Raines, Ronald T.

    2010-01-01

    Proteins have become accessible targets for chemical synthesis. The basic strategy is to use native chemical ligation, Staudinger ligation, or other orthogonal chemical reactions to couple synthetic peptides. The ligation reactions are compatible with a variety of solvents and proceed in solution or on a solid support. Chemical synthesis enables a level of control on protein composition that greatly exceeds that attainable with ribosome-mediated biosynthesis. Accordingly, the chemical synthesis of proteins is providing previously unattainable insight into the structure and function of proteins. PMID:15869385

  6. Gas Phase Nanoparticle Synthesis

    NASA Astrophysics Data System (ADS)

    Granqvist, Claes; Kish, Laszlo; Marlow, William

    This book deals with gas-phase nanoparticle synthesis and is intended for researchers and research students in nanomaterials science and engineering, condensed matter physics and chemistry, and aerosol science. Gas-phase nanoparticle synthesis is instrumental to nanotechnology - a field in current focus that raises hopes for environmentally benign, resource-lean manufacturing. Nanoparticles can be produced by many physical, chemical, and even biological routes. Gas-phase synthesis is particularly interesting since one can achieve accurate manufacturing control and hence industrial viability.

  7. Mechanochemical organic synthesis.

    PubMed

    Wang, Guan-Wu

    2013-09-21

    Recently, mechanical milling using a mixer mill or planetary mill has been fruitfully utilized in organic synthesis under solvent-free conditions. This review article provides a comprehensive overview of various solvent-free mechanochemical organic reactions, including metal-mediated or -catalyzed reactions, condensation reactions, nucleophilic additions, cascade reactions, Diels-Alder reactions, oxidations, reductions, halogenation/aminohalogenation, etc. The ball milling technique has also been applied to the synthesis of calixarenes, rotaxanes and cage compounds, asymmetric synthesis as well as the transformation of biologically active compounds.

  8. Method of sound synthesis

    DOEpatents

    Miner, Nadine E.; Caudell, Thomas P.

    2004-06-08

    A sound synthesis method for modeling and synthesizing dynamic, parameterized sounds. The sound synthesis method yields perceptually convincing sounds and provides flexibility through model parameterization. By manipulating model parameters, a variety of related, but perceptually different sounds can be generated. The result is subtle changes in sounds, in addition to synthesis of a variety of sounds, all from a small set of models. The sound models can change dynamically according to changes in the simulation environment. The method is applicable to both stochastic (impulse-based) and non-stochastic (pitched) sounds.

  9. Hydrothermal organic synthesis experiments

    NASA Technical Reports Server (NTRS)

    Shock, Everett L.

    1992-01-01

    Ways in which heat is useful in organic synthesis experiments are described, and experiments on the hydrothermal destruction and synthesis of organic compounds are discussed. It is pointed out that, if heat can overcome kinetic barriers to the formation of metastable states from reduced or oxidized starting materials, abiotic synthesis under hydrothermal conditions is a distinct possibility. However, carefully controlled experiments which replicate the descriptive variables of natural hydrothermal systems have not yet been conducted with the aim of testing the hypothesis of hydrothermal organic systems.

  10. Synthesis of amino acids

    DOEpatents

    Davis, J.W. Jr.

    1979-09-21

    A method is described for synthesizing amino acids preceding through novel intermediates of the formulas: R/sub 1/R/sub 2/C(OSOC1)CN, R/sub 1/R/sub 2/C(C1)CN and (R/sub 1/R/sub 2/C(CN)O)/sub 2/SO wherein R/sub 1/ and R/sub 2/ are each selected from hydrogen and monovalent hydrocarbon radicals of 1 to 10 carbon atoms. The use of these intermediates allows the synthesis steps to be exothermic and results in an overall synthesis method which is faster than the synthesis methods of the prior art.

  11. Enantioselective Synthesis of (+)-Majusculone

    PubMed Central

    Taber, Douglass F.; Sikkander, M. Inthikhab; Storck, Pierre H.

    2011-01-01

    The first enantioselective synthesis of a chamigrane sesquiterpene, (+)-majusculone, has been completed. The quaternary center was generated asymmetrically by alkylidene carbene insertion, with retention of absolute configuration, from a diastereomerically pure ketal. PMID:17447815

  12. Total synthesis of atropurpuran

    PubMed Central

    Gong, Jing; Chen, Huan; Liu, Xiao-Yu; Wang, Zhi-Xiu; Nie, Wei; Qin, Yong

    2016-01-01

    Due to their architectural intricacy and biological significance, the synthesis of polycyclic diterpenes and their biogenetically related alkaloids have been the subject of considerable interest over the last few decades, with progress including the impressive synthesis of several elusive targets. Despite tremendous efforts, conquering the unique structural types of this large natural product family remains a long-term challenge. The arcutane diterpenes and related alkaloids, bearing a congested tetracyclo[5.3.3.04,9.04,12]tridecane unit, are included in these unsolved enigmas. Here we report a concise approach to the construction of the core structure of these molecules and the first total synthesis of (±)-atropurpuran. Pivotal features of the synthesis include an oxidative dearomatization/intramolecular Diels-Alder cycloaddition cascade, sequential aldol and ketyl-olefin cyclizations to assemble the highly caged framework, and a chemoselective and stereoselective reduction to install the requisite allylic hydroxyl group in the target molecule. PMID:27387707

  13. Synthesis of Potential Trypanocides

    DTIC Science & Technology

    1987-12-01

    Keywords: antiparasitic, trypanosomiasis , chemotherapy , 03 trypanocides, synthesis, heteroaromatic, heterocyclic 6 18 19, ABSTRACT (Continue on reverse if... trypanosomiasis (T. rhodesiense) infections in mice. A standard protocol was used in which groups of five mice were treated by subcutaneous injection with a...C. J. Bacchi, "Content, Synthesis, and Function of Polyamines i. Trypanosomatides: Relationship to Chemotherapy ," J. Protozool., 28, 20 . p (1981); C

  14. Synthesis of Energetic Materials.

    DTIC Science & Technology

    1986-03-31

    1 ) ................... 2 2 GPC of Polyformal of Decafluorodiol ( 2 ) .......................... 4 3 GPC of Polyformal of...turn: ( 1 ) synthesis of energetic monomers and polymers, and ( 2 ) synthesis of polycyclic and adamantoid nitramines. Both tasks were continuations of...preparation of 2,2,3,3,4,4-hexafluoropentane-l,lidiol polyformal (FPF- 1 ) by the 2 step sequence shown below was reported. " HOCH2 (CF2 )3CH20H + (CH20) 3

  15. Benzothiazines in Synthesis. A Formal Total Synthesis of Pseudopteroxazole

    PubMed Central

    Harmata, Michael; Cai, Zhengxin; Chen, Yugang

    2010-01-01

    A formal total synthesis of the antitubercular natural product was accomplished. This work was undertaken to address certain stereochemical problems in our initial synthesis. By using an ester group as a surrogate for a methyl group, we were able to intercept a key intermediate in our first synthesis with better selectivity and greater convergence than had previously been the case. PMID:19537725

  16. The Synthesis of Lepidoptera Pheromones

    NASA Astrophysics Data System (ADS)

    Matveeva, Elena D.; Kurts, A. L.; Bundel', Yurii G.

    1986-07-01

    The review surveys the data in numerous publications of the synthesis of the pheromones of scale-winged insects (Lepidoptera). Attention is concentrated on problems of the sterospecific synthesis of pheromones. The bibliography includes 217 references.

  17. Shell's Middle Distillate Synthesis process

    SciTech Connect

    Voetter, H.; VanDerBurgt, M.J. B.V., The Hague )

    1988-01-01

    The basis of the Shell Middle Distillate Synthesis (SMDS) process is the classic Fischer-Tropsch synthesis. For the case of middle distillate production from natural gas the procedure has been developed to commercial maturity, making use of tailored line-up for synthesis gas production and of proprietary modern catalysts in synthesis. Development work over the last years has in particular lead to improvement of the economy of the process altogether via catalyst performance, reactor sizing and syngas manufacturing line-up.

  18. Revisiting Methods of Literature Synthesis.

    ERIC Educational Resources Information Center

    Suri, Harsh; Clarke, David

    This paper highlights the relative strengths and weaknesses of the contemporary methods of research synthesis and proposes a multistage approach to research synthesis that draws on the strengths of each of these individual methods. In this approach, the decisions at every step of the synthesis process are guided by the nature of the data. The…

  19. Big6 Turbotools and Synthesis

    ERIC Educational Resources Information Center

    Tooley, Melinda

    2005-01-01

    The different tools that are helpful during the Synthesis stage, their role in boosting students abilities in Synthesis and the way in which it can be customized to meet the needs of each group of students are discussed. Big6 TurboTools offers several tools to help complete the task. In Synthesis stage, these same tools along with Turbo Report and…

  20. Crystal structure of 1-(4-formyl­benzyl­idene)thio­semicarbazone

    PubMed Central

    Carballo, Rosa; Pino-Cuevas, Arantxa; Vázquez-López, Ezequiel M.

    2014-01-01

    The asymmetric unit of the title compound, C9H9N3OS, contains two approximately planar mol­ecules (r.m.s. deviations for 14 non-H atoms = 0.094 and 0.045 Å), with different conformations. In one of them, the C=O group is syn to the S atom and in the other it is anti. Each mol­ecule features an intra­molecular N—H⋯N hydrogen bond, which generates an S(5) ring. In the crystal, mol­ecules are linked by N—H⋯O and N—H⋯S hydrogen bonds, generating discrete networks; the syn mol­ecules form [010] chains and the anti mol­ecules form (100) sheets. PMID:25309285

  1. Glycals in enantiospecific synthesis

    NASA Astrophysics Data System (ADS)

    Tolstikov, Alexander G.; Tolstikov, Genrikh A.

    1993-06-01

    The reactions of 1,2-unsaturated sugars (glycals) are considered in this review in relation to problems of the enantiospecific synthesis of natural products, their fragments, and their analogues. The reactions occurring both with retention of the heterocycle and those carried out with the aim of obtaining open chain chiral units are discussed. It is shown that the use of glycals as a stock of chiral substances which determine the configuration of the asymmetric centres in the target products of multistage synthesis is promising. Schemes for the synthesis of natural products of different types are considered: O- and C-glycosides, nucleosides, oligosaccharides, pheromones, antibiotics, toxins, glycosphingolipids, etc. The bibliography includes 161 references.

  2. Synthesis of organosilicon compounds

    SciTech Connect

    Zhao, G.

    1996-01-01

    Silicon-containing polymers have been a focus of synthesis and study in Dr. Barton`s group because of their chemistry and properties which are not offered by other systems or materials. For example, the polymer -[-SiMe2C≡C-]n-can be easily processed to films or fibers from melt or solution, and thermally converted to a SiC-containing ceramic in high yield at high temperature. In recent years, carbosilane dendritic polymers have been of great interests in many research groups. However, no synthesis of carbosilane dendrimers with functionalties both inside and outside the dendrimer has been reported. Functionality is very important in the synthesis of preceramic polymers. This thesis will be devoted to exploring several new organosilicon polymer systems.

  3. Synthesis of taurospongin A.

    PubMed

    Wu, Boshen; Mallinger, Aurélie; Robertson, Jeremy

    2010-06-18

    Two new routes to the C(1-10) carboxylic acid core of taurospongin A are presented. In the first route, overall asymmetric hydration of a C(2)-C(3) alkene is achieved by Sharpless AD and selective deoxygenation at C(2); in the second route, the C(3) stereogenic center is set by Tietze asymmetric allylation. A short synthesis of the C(1'-25') fatty acid combines with the product from the first route to complete the total synthesis of taurospongin A.

  4. Distributed aperture synthesis.

    PubMed

    Rabb, David; Jameson, Douglas; Stokes, Andrew; Stafford, Jason

    2010-05-10

    Distributed aperture synthesis is an exciting technique for recovering high-resolution images from an array of small telescopes. Such a system requires optical field values measured at individual apertures to be phased together so that a single, high-resolution image can be synthesized. This paper describes the application of sharpness metrics to the process of phasing multiple coherent imaging systems into a single high-resolution system. Furthermore, this paper will discuss hardware and present the results of simulations and experiments which will illustrate how aperture synthesis is performed.

  5. Supercritical synthesis of biodiesel.

    PubMed

    Bernal, Juana M; Lozano, Pedro; García-Verdugo, Eduardo; Burguete, M Isabel; Sánchez-Gómez, Gregorio; López-López, Gregorio; Pucheault, Mathieu; Vaultier, Michel; Luis, Santiago V

    2012-07-23

    The synthesis of biodiesel fuel from lipids (vegetable oils and animal fats) has gained in importance as a possible source of renewable non-fossil energy in an attempt to reduce our dependence on petroleum-based fuels. The catalytic processes commonly used for the production of biodiesel fuel present a series of limitations and drawbacks, among them the high energy consumption required for complex purification operations and undesirable side reactions. Supercritical fluid (SCF) technologies offer an interesting alternative to conventional processes for preparing biodiesel. This review highlights the advances, advantages, drawbacks and new tendencies involved in the use of supercritical fluids (SCFs) for biodiesel synthesis.

  6. Synthesis: Intertwining product and process

    NASA Technical Reports Server (NTRS)

    Weiss, David M.

    1990-01-01

    Synthesis is a proposed systematic process for rapidly creating different members of a program family. Family members are described by variations in their requirements. Requirements variations are mapped to variations on a standard design to generate production quality code and documentation. The approach is made feasible by using principles underlying design for change. Synthesis incorporates ideas from rapid prototyping, application generators, and domain analysis. The goals of Synthesis and the Synthesis process are discussed. The technology needed and the feasibility of the approach are also briefly discussed. The status of current efforts to implement Synthesis methodologies is presented.

  7. Synthesis of Chemiluminescent Esters: A Combinatorial Synthesis Experiment for Organic Chemistry Students

    ERIC Educational Resources Information Center

    Duarte, Robert; Nielson, Janne T.; Dragojlovic, Veljko

    2004-01-01

    A group of techniques aimed at synthesizing a large number of structurally diverse compounds is called combinatorial synthesis. Synthesis of chemiluminescence esters using parallel combinatorial synthesis and mix-and-split combinatorial synthesis is experimented.

  8. Multi-Frequency Synthesis

    NASA Astrophysics Data System (ADS)

    Conway, J. E.; Sault, R. J.

    Introduction; Image Fidelity; Multi-Frequency Synthesis; Spectral Effects; The Spectral Expansion; Spectral Dirty Beams; First Order Spectral Errors; Second Order Spectral Errors; The MFS Deconvolution Problem; Nature of The Problem; Map and Stack; Direct Assault; Data Weighting Methods; Double Deconvolution; The Sault Algorithm; Multi-Frequency Self-Calibration; Practical MFS; Conclusions

  9. Synthesis in Science.

    ERIC Educational Resources Information Center

    Horsella, Maria

    This paper discusses various techniques that scientists and other professionals can use to keep current in their field despite the large amount of available information, such as consulting abstracts, indexes, reviews, and catalogues. It also examines specific language patterns that are used in the sciences to produce synthesis and abridgement,…

  10. Total Synthesis of Kopsinine

    PubMed Central

    Xie, Jian; Wolfe, Amanda L.; Boger, Dale L.

    2013-01-01

    The use of a powerful intramolecular [4 + 2]/[3 + 2] cycloaddition cascade of an 1,3,4-oxadiazole in the divergent total synthesis of kopsinine (1), featuring an additional unique SmI2-promoted transannular cyclization reaction for formation of the bicyclo[2.2.2]octane central to its hexacyclic ring system, is detailed. PMID:23391149

  11. Oxenoids in organic synthesis.

    PubMed

    Minko, Yury; Marek, Ilan

    2014-03-14

    Experimental and theoretical studies of metalated peroxides confirmed their unique properties as oxenoids (electrophilic oxidants) allowing for a highly selective and efficient oxidation processes of nucleophilic organometallic species. In this short review we present the most prominent examples of the application of this class of reagents towards organic synthesis.

  12. MICROWAVES IN ORGANIC SYNTHESIS

    EPA Science Inventory

    The effect of microwaves, a non-ionizing radiation, on organic reactions is described both in polar solvents and under solvent-free conditions. The special applications are highlighted in the context of solventless organic synthesis which involve microwave (MW) exposure of neat r...

  13. The total synthesis of psymberin.

    PubMed

    Huang, Xianhai; Shao, Ning; Palani, Anandan; Aslanian, Robert; Buevich, Alexei

    2007-06-21

    The total synthesis of a new member of the pederin family of natural products, psymberin 1, was accomplished. Using a recently reported novel and efficient PhI(OAc)2 mediated oxidative entry to 2-(N-acylaminal)-substituted tetrahydropyrans as the key step, this total synthesis was executed in a convergent and efficient manner. The longest linear sequence of this synthesis was 22 steps starting from known 6.

  14. Total synthesis of clostrubin

    PubMed Central

    Yang, Ming; Li, Jian; Li, Ang

    2015-01-01

    Clostrubin is a potent antibiotic against methicillin- and vancomycin-resistant bacteria that was isolated from a strictly anaerobic bacterium Clostridium beijerinckii in 2014. This polyphenol possesses a fully substituted arene moiety on its pentacyclic scaffold, which poses a considerable challenge for chemical synthesis. Here we report the first total synthesis of clostrubin in nine steps (the longest linear sequence). A desymmetrization strategy is exploited based on the inherent structural feature of the natural product. Barton–Kellogg olefination forges the two segments together to form a tetrasubstituted alkene. A photo-induced 6π electrocyclization followed by spontaneous aromatization constructs the hexasubstituted B ring at a late stage. In total, 200 mg of clostrubin are delivered through this approach. PMID:25759087

  15. Prebiotic synthesis of histidine

    NASA Technical Reports Server (NTRS)

    Shen, C.; Yang, L.; Miller, S. L.; Oro, J.

    1990-01-01

    The prebiotic formation of histidine (His) has been accomplished experimentally by the reaction of erythrose with formamidine followed by a Strecker synthesis. In the first step of this reaction sequence, the formation of imidazole-4-acetaldehyde took place by the condensation of erythrose and formamidine, two compounds that are known to be formed under prebiotic conditions. In a second step, the imidazole-4-acetaldehyde was converted to His, without isolation of the reaction products by adding HCN and ammonia to the reaction mixture. LC, HPLC, thermospray liquid chromatography-mass spectrometry, and tandem mass spectrometry were used to identify the product, which was obtained in a yield of 3.5% based on the ratio of His/erythrose. This is a new chemical synthesis of one of the basic amino acids which had not been synthesized prebiotically until now.

  16. Continuous organic electrochemical synthesis

    SciTech Connect

    Nobe, K.; Baizer, M.; Pintauro, P.; Park, K.; Gilbert, S.

    1984-07-01

    The electrochemical oxidation of glucose to gluconic acid and reduction of glucose to sorbitol has been successfully paired in an undivided packed bed electrode flow cell. The use of a Raney nickel powder catalytic cathode significantly improved the current efficiency for sorbitol production, as compared to a high hydrogen overpotential Zn(Hg) cathode. The optimum operating conditions for the paired synthesis are: activity W-2 Raney nickel powder cathode, graphite chip anode, a 1.6 M glucose and 0.4 M CaBr/sub 2/ initial solution composition, pH 6-7, 60/sup 0/C solution temperature, a current density of 250 to 500 mA and a solution volumetric flow rate of 100 ml min/sup -1/. Under these conditions the sorbitol current efficiencies are at least 80%, the glucose acid current efficiencies are 100% and the product yields are quantitative. A separation scheme for the paired synthesis has also been devised. It consists of the precipitation of the oxidation product (calcium gluconate) and the ethanol extraction of glucose and CaBr/sub 2/ from sorbitol. Based on a preliminary economic analysis of the cost of raw materials, energy and the electrochemical cell and separation equipment the cost of producing 1 lb calcium gluconate and 0.68 lb sorbitol in a paired synthesis was estimated to be $0.896. The cost of producing the same amount of sorbitol and calcium gluconate in separate electrochemical cells was calculated to be $1.20. Thus, the paired synthesis appears to be an economically viable process.

  17. [Meta-synthesis].

    PubMed

    Debout, Christophe

    2016-01-01

    Nursing science's body of knowledge is mainly composed of the results of qualitative studies which, since the 1970s, have contributed notably to improving understanding of patients' experiences. This abundant scientific literature enables reviews to be carried out with the aim of producing solid theories. Meta-synthesis is a methodology which was created for this purpose. The theories which it produces constitute reference frameworks for researchers wishing to develop innovative nursing procedures and to test them within the context of clinical studies.

  18. Extended cooperative control synthesis

    NASA Technical Reports Server (NTRS)

    Davidson, John B.; Schmidt, David K.

    1994-01-01

    This paper reports on research for extending the Cooperative Control Synthesis methodology to include a more accurate modeling of the pilot's controller dynamics. Cooperative Control Synthesis (CCS) is a methodology that addresses the problem of how to design control laws for piloted, high-order, multivariate systems and/or non-conventional dynamic configurations in the absence of flying qualities specifications. This is accomplished by emphasizing the parallel structure inherent in any pilot-controlled, augmented vehicle. The original CCS methodology is extended to include the Modified Optimal Control Model (MOCM), which is based upon the optimal control model of the human operator developed by Kleinman, Baron, and Levison in 1970. This model provides a modeling of the pilot's compensation dynamics that is more accurate than the simplified pilot dynamic representation currently in the CCS methodology. Inclusion of the MOCM into the CCS also enables the modeling of pilot-observation perception thresholds and pilot-observation attention allocation affects. This Extended Cooperative Control Synthesis (ECCS) allows for the direct calculation of pilot and system open- and closed-loop transfer functions in pole/zero form and is readily implemented in current software capable of analysis and design for dynamic systems. Example results based upon synthesizing an augmentation control law for an acceleration command system in a compensatory tracking task using the ECCS are compared with a similar synthesis performed by using the original CCS methodology. The ECCS is shown to provide augmentation control laws that yield more favorable, predicted closed-loop flying qualities and tracking performance than those synthesized using the original CCS methodology.

  19. Total synthesis of teixobactin

    NASA Astrophysics Data System (ADS)

    Jin, Kang; Sam, Iek Hou; Po, Kathy Hiu Laam; Lin, Du'an; Ghazvini Zadeh, Ebrahim H.; Chen, Sheng; Yuan, Yu; Li, Xuechen

    2016-08-01

    To cope with the global bacterial multidrug resistance, scientific communities have devoted significant efforts to develop novel antibiotics, particularly those with new modes of actions. Teixobactin, recently isolated from uncultured bacteria, is considered as a promising first-in-class drug candidate for clinical development. Herein, we report its total synthesis by a highly convergent Ser ligation approach and this strategy allows us to prepare several analogues of the natural product.

  20. Synthesis of Alocasin A.

    PubMed

    Kim, Se Hun; Sperry, Jonathan

    2015-12-24

    Herein is reported a synthesis of alocasin A (1), an alkaloid component of Alocasia macrorrhiza, a herbaceous plant used in folk medicine throughout southern Asia. A double Suzuki-Miyaura cross-coupling reaction between a 3-borylindole and 2,5-dibromopyrazine was used to assemble the heteroaromatic framework of the natural product. Removal of the protecting groups gave a synthetic sample of 1, the spectroscopic data of which matched those in the isolation report of this compound.

  1. Adaptive aperture synthesis

    NASA Astrophysics Data System (ADS)

    Johnson, A. M.; Zhang, S.; Mudassar, A.; Love, G. D.; Greenaway, A. H.

    2005-12-01

    High-resolution imaging can be achieved by optical aperture synthesis (OAS). Such an imaging process is subject to aberrations introduced by instrumental defects and/or turbulent media. Redundant spacings calibration (RSC) is a snapshot calibration technique that can be used to calibrate OAS arrays without use of assumptions about the object being imaged. Here we investigate the analogies between RSC and adaptive optics in passive imaging applications.

  2. Synthesis of SYEP Plasticizer

    DTIC Science & Technology

    1975-10-01

    enerjy functional groups are direct fluorination of dinitrocompounds (Ref. l) and reaction of ketones with difluoramine (Ref. 2). Because the ether...containing the maximum number of these energetic groups . The target compound of this study was 1,3-bis(fluorodinitroethoxy)-2,2-bis(difluor- aiiiino...FEASIBILITY STUDY The proposed synthesis of SYEP required dlfluoranlnation of 1,3- blG (fluoro- dlnitroethoxy)acetone with difluoraraine in a stronc

  3. Synthesis at the molecular frontier

    PubMed Central

    Wender, Paul A.; Miller, Benjamin L.

    2010-01-01

    Driven by remarkable advances in the understanding of structure and reaction mechanisms, organic synthesis will be increasingly directed to producing bioinspired and newly designed molecules. PMID:19587760

  4. Synthesis of mercury cuprates

    NASA Astrophysics Data System (ADS)

    Odier, P.; Sin, A.; Toulemonde, P.; Bailly, A.; LeFloch, S.

    2000-08-01

    Mercury cuprates have very interesting potential applications that have not been thoroughly explored until now because of the complexity of their synthesis. This paper presents an overview of recent results concerning their processing. At first, a simple sol-gel technique is described that permits one to easily and intimately mix the precursors. The method uses the gelification of an inorganic solution of the cations by acrylamide polymerization. Mercuration of the precursor at moderate pressures (<2-5 MPa) is then discussed. The control of the total pressure during the synthesis by a simple method is shown, and this enables one to quantify some important parameters of the synthesis and to optimize the superconducting properties. This method has been also used successfully to incorporate mercury into layers of precursors and then to form thick layers of superconducting (Hg, Re)-1223, c-axis oriented. Finally, mercuration at higher pressures (up to 6 GPa) is considered and the case of the double mercury layer Hg-2212 is discussed in connection with the oxygen content of the reactants.

  5. Bayesian Face Sketch Synthesis.

    PubMed

    Wang, Nannan; Gao, Xinbo; Sun, Leiyu; Li, Jie

    2017-03-01

    Exemplar-based face sketch synthesis has been widely applied to both digital entertainment and law enforcement. In this paper, we propose a Bayesian framework for face sketch synthesis, which provides a systematic interpretation for understanding the common properties and intrinsic difference in different methods from the perspective of probabilistic graphical models. The proposed Bayesian framework consists of two parts: the neighbor selection model and the weight computation model. Within the proposed framework, we further propose a Bayesian face sketch synthesis method. The essential rationale behind the proposed Bayesian method is that we take the spatial neighboring constraint between adjacent image patches into consideration for both aforementioned models, while the state-of-the-art methods neglect the constraint either in the neighbor selection model or in the weight computation model. Extensive experiments on the Chinese University of Hong Kong face sketch database demonstrate that the proposed Bayesian method could achieve superior performance compared with the state-of-the-art methods in terms of both subjective perceptions and objective evaluations.

  6. Aircraft noise synthesis system

    NASA Astrophysics Data System (ADS)

    McCurdy, David A.; Grandle, Robert E.

    1987-02-01

    A second-generation Aircraft Noise Synthesis System has been developed to provide test stimuli for studies of community annoyance to aircraft flyover noise. The computer-based system generates realistic, time-varying, audio simulations of aircraft flyover noise at a specified observer location on the ground. The synthesis takes into account the time-varying aircraft position relative to the observer; specified reference spectra consisting of broadband, narrowband, and pure-tone components; directivity patterns; Doppler shift; atmospheric effects; and ground effects. These parameters can be specified and controlled in such a way as to generate stimuli in which certain noise characteristics, such as duration or tonal content, are independently varied, while the remaining characteristics, such as broadband content, are held constant. The system can also generate simulations of the predicted noise characteristics of future aircraft. A description of the synthesis system and a discussion of the algorithms and methods used to generate the simulations are provided. An appendix describing the input data and providing user instructions is also included.

  7. Aircraft noise synthesis system

    NASA Technical Reports Server (NTRS)

    Mccurdy, David A.; Grandle, Robert E.

    1987-01-01

    A second-generation Aircraft Noise Synthesis System has been developed to provide test stimuli for studies of community annoyance to aircraft flyover noise. The computer-based system generates realistic, time-varying, audio simulations of aircraft flyover noise at a specified observer location on the ground. The synthesis takes into account the time-varying aircraft position relative to the observer; specified reference spectra consisting of broadband, narrowband, and pure-tone components; directivity patterns; Doppler shift; atmospheric effects; and ground effects. These parameters can be specified and controlled in such a way as to generate stimuli in which certain noise characteristics, such as duration or tonal content, are independently varied, while the remaining characteristics, such as broadband content, are held constant. The system can also generate simulations of the predicted noise characteristics of future aircraft. A description of the synthesis system and a discussion of the algorithms and methods used to generate the simulations are provided. An appendix describing the input data and providing user instructions is also included.

  8. Gold Nanoparticle Microwave Synthesis

    SciTech Connect

    Krantz, Kelsie E.; Christian, Jonathan H.; Coopersmith, Kaitlin; Washington, II, Aaron L.; Murph, Simona H.

    2016-07-27

    At the nanometer scale, numerous compounds display different properties than those found in bulk material that can prove useful in areas such as medicinal chemistry. Gold nanoparticles, for example, display promise in newly developed hyperthermia therapies for cancer treatment. Currently, gold nanoparticle synthesis is performed via the hot injection technique which has large variability in final particle size and a longer reaction time. One underdeveloped area by which these particles could be produced is through microwave synthesis. To initiate heating, microwaves agitate polar molecules creating a vibration that gives off the heat energy needed. Previous studies have used microwaves for gold nanoparticle synthesis; however, polar solvents were used that partially absorbed incident microwaves, leading to partial thermal heating of the sample rather than taking full advantage of the microwave to solely heat the gold nanoparticle precursors in a non-polar solution. Through this project, microwaves were utilized as the sole heat source, and non-polar solvents were used to explore the effects of microwave heating only as pertains to the precursor material. Our findings show that the use of non-polar solvents allows for more rapid heating as compared to polar solvents, and a reduction in reaction time from 10 minutes to 1 minute; this maximizes the efficiency of the reaction, and allows for reproducibility in the size/shape of the fabricated nanoparticles.

  9. Rubber Research. The Synthesis of Unsaturated Fluorocarbons.

    DTIC Science & Technology

    HALOGENATED HYDROCARBONS, SYNTHESIS(CHEMISTRY)), (*NITROSO COMPOUNDS, SYNTHESIS(CHEMISTRY)), FLUORINE COMPOUNDS, CHLORINE COMPOUNDS, ORGANIC SOLVENTS, ALKENES, IRON COMPOUNDS, PHOTOLYSIS, ACETIC ANHYDRIDE, ACETIC ACID

  10. Hydrothermal organic synthesis experiments

    NASA Technical Reports Server (NTRS)

    Shock, Everett L.

    1992-01-01

    The serious scientific debate about spontaneous generation which raged for centuries reached a climax in the nineteenth century with the work of Spallanzani, Schwann, Tyndall, and Pasteur. These investigators demonstrated that spontaneous generation from dead organic matter does not occur. Although no aspects of these experiments addressed the issue of whether organic compounds could be synthesized abiotically, the impact of the experiments was great enough to cause many investigators to assume that life and its organic compounds were somehow fundamentally different than inorganic compounds. Meanwhile, other nineteenth-century investigators were showing that organic compounds could indeed be synthesized from inorganic compounds. In 1828 Friedrich Wohler synthesized urea in an attempt to form ammonium cyanate by heating a solution containing ammonia and cyanic acid. This experiment is generally recognized to be the first to bridge the artificial gap between organic and inorganic chemistry, but it also showed the usefulness of heat in organic synthesis. Not only does an increase in temperature enhance the rate of urea synthesis, but Walker and Hambly showed that equilibrium between urea and ammonium cyanate was attainable and reversible at 100 C. Wohler's synthesis of urea, and subsequent syntheses of organic compounds from inorganic compounds over the next several decades dealt serious blows to the 'vital force' concept which held that: (1) organic compounds owe their formation to the action of a special force in living organisms; and (2) forces which determine the behavior of inorganic compounds play no part in living systems. Nevertheless, such progress was overshadowed by Pasteur's refutation of spontaneous generation which nearly extinguished experimental investigations into the origins of life for several decades. Vitalism was dealt a deadly blow in the 1950's with Miller's famous spark-discharge experiments which were undertaken in the framework of the Oparin

  11. Lactobacillusassisted synthesis of titanium nanoparticles

    PubMed Central

    2007-01-01

    An eco-friendlylactobacillussp. (microbe) assisted synthesis of titanium nanoparticles is reported. The synthesis is performed at room temperature. X-ray and transmission electron microscopy analyses are performed to ascertain the formation of Ti nanoparticles. Individual nanoparticles as well as a number of aggregates almost spherical in shape having a size of 40–60 nm are found.

  12. Total Synthesis of Amphidinolide E

    PubMed Central

    Va, Porino; Roush, William R.

    2008-01-01

    A convergent and highly stereocontrolled synthesis of amphidinolide E (1) has been accomplished. The synthesis features a highly diastereoselective (>20:1) BF3·Et2O promoted [3+2] annulation reaction between aldehyde 3 and allylsilane 4 to afford substituted tetrahydrofuran 2. PMID:17165709

  13. Preparation of ammonia synthesis gas

    SciTech Connect

    Shires, P.J.; van Dijk, C.P.; Cassata, J.R.; Mandelik, B.G.

    1984-10-30

    Ammonia synthesis gas having excess nitrogen is produced in a reactor-exchanger primary reformer followed by an autothermal secondary reformer wherein process air for the latter is preheated by heat exchange with gas turbine exhaust and the primary reformer is heated by synthesis gas from the secondary reformer.

  14. Total Synthesis of Propolisbenzofuran B†

    PubMed Central

    Jones, Brian T.; Avetta, Christopher T.; Thomson, Regan J.

    2014-01-01

    The first total synthesis of propolisbenzofuran B, a bioactive natural product isolated from honeybee propolis resin, is reported. The convergent synthesis makes use of a silicon-tether controlled oxidative ketone–ketone cross-coupling and a novel benzofuran-generating cascade reaction to deliver the core structure of the natural product from readily prepared precursors. PMID:24976944

  15. Enantioselective synthesis of (-)-basiliskamide A.

    PubMed

    Chen, Ming; Roush, William R

    2012-03-16

    Basiliskamide A is an antifungal polyketide natural product isolated by Andersen and co-workers from a Bacillus laterosporus isolate, PNG-276. A nine-step enantioselective synthesis of (-)-basiliskamide A is reported, starting from commercially available β-hydroxy ester 7. The synthesis features a highly diastereoselective mismatched double asymmetric δ-stannylallylboration reaction of aldehyde 5 with the bifunctional allylborane reagent 4.

  16. Lung epinephrine synthesis

    SciTech Connect

    Kennedy, B.; Elayan, H.; Ziegler, M.G. )

    1990-04-01

    We studied in vitro and in vivo epinephrine (E) synthesis by rat lung. Nine days after removal of the adrenal medullas, circulating E was reduced to 7% of levels found in sham-operated rats but 30% of lung E remained. Treatment of demedullated rats with 6 hydroxydopamine plus reserpine did not further reduce lung E. In the presence of S-(3H)adenosylmethionine lung homogenates readily N-methylated norepinephrine (NE) to form (3H)E. The rate of E synthesis by lung homogenates was progressively more rapid with increasing NE up to a concentration of 3 mM, above which it declined. The rate of E formation was optimal at an incubation pH of 8 and at temperatures of approximately 55 degrees C. We compared the E-forming enzyme(s) of lung homogenates with those of adrenal and cardiac ventricle. The adrenal contains mainly phenylethanolamine N-methyltransferase (PNMT), which is readily inhibited by SKF 29661 and methylates dopamine (DA) very poorly. Cardiac ventricles contain mainly nonspecific N-methyltransferase (NMT), which is poorly inhibited by SKF 29661 and readily methylates both DA and NE. Lung homogenates were inhibited by SKF 29661 about half as well as adrenal but more than ventricle. We used the rate of E formation from NE as an index of PNMT-like activity and deoxyepinephrine synthesis from DA as an index of NMT-like activity. PNMT and NMT activity in rat lung homogenates were not correlated with each other, displayed different responses to change in temperature, and were affected differently by glucocorticoids.

  17. Multi-Frequency Synthesis

    NASA Astrophysics Data System (ADS)

    Sault, R. J.; Conway, J. E.

    Multi-frequency synthesis is the practice of using visibility data measured over a range of frequencies when forming a continuum image. Because observing frequency is easier to vary than antenna location, it is an effective way of filling the (u,v) plane for an observation. Here we consider the artifacts in MFS images caused by source spectral variation. For frequency ranges of about 30%, for observations where only modest dynamic range is required, the artifacts of MFS can be completely ignored. For higher dynamic range observations, some calibration techniques and deconvolution algorithms are described which minimize the artifacts.

  18. [New synthesis empathogenic agents].

    PubMed

    Velea, D; Hautefeuille, M; Vazeille, G; Lantran-Davoux, C

    1999-01-01

    The use of synthesis drugs is the object of numerous written articles and TV programs in the last, decade. These synthesis drugs or "designer drugs", are well known for their ability to enhance, reinforce or appease social difficulties and relationships. In the research for empathetic and entactogenic relations one discover an obvious lack of communication and "warmth" in personal or professional relationship. An image of chemical "well being" has become a frequent stereotype of a society with an atrophying of performance and values while supposedly dedicating itself to individual performance. The youths are the first victims of these new drugs, the economical and social environment are the main reinforcing factors of this behaviour. The main characteristic of these drugs, is the non-recognition of their danger, some users go so far as to describe this category of substances as "drugs which are not drugs". As a characteristic, the use of a these synthesis drugs is almost recreative, during the week-end and holiday. The drug addiction is different than that of opiates or cocaine. One can observe some cases of real dependence--corresponding to the DSW IV criterion--when the personality of the users is the main characteristic (narcissic failure, immature personality, family and school problems). Many adverse effects--hypertension, kidney failure, psychoses--were declared. The mass-media has presented many articles concerning Ecstasy (MDMA). This is the most used drug during the rave parties. Its adverse effects are well known and proven. The authors would like to present other more recent synthesis drugs, also known as "analogs". These drugs, a kind of mixture between amphetamine-like (MDMA, MBDB, MDA) and misused medicines (ketamine, gamma OH, atropine) represent a real danger. GHB, 2 CB, HMB, are some of these recent substances. The possibility to procure them on the Web, or to produce them by oneself, add to their danger because of the lack of controls on toxicity

  19. Synthesis of Laser Dyes

    DTIC Science & Technology

    1988-11-09

    block number) This report describes the progress made in attempts to prepare seven laser dyes. These dyes all have a 2-(L-pyridy.)-1,3- oxazole ...structure one dye, The synthesis of one dye, 2-(Ni-met.hyl-4-pyridiniiumi)pherianthroL9,10-dJ-1,3- oxazole tosylate (I) has been com-pleted. Preliminary...1,3- oxazoles . I~ 20 [IISTRI:’UTIGTJi/AVAILABILITY OF ABSTRACT 21. ABSTRACT SECURITY CLASSIFICATION 0UNITILA-,SIFIEDI.JNLiITED 0 SAME AS RPT El DTIC

  20. Aperture synthesis in space

    NASA Astrophysics Data System (ADS)

    Faucherre, Michel; Greenaway, A. H.; Merkle, F.; Noordam, J. E.; Perryman, M. A. C.

    1989-09-01

    The principles of optical aperture synthesis (OAS), which can yield images of much higher resolution than current ground observations, are essentially those of radio astronomy, and may be used in either space- or ground-based studies of the stellar envelopes around Be stars, the internal dynamics of active galaxies, etc. An account is presently given of possible OAS instrument configurations; it is shown that a large field of view can be achieved, so that the instrument may be calibrated on bright stars during the observation of faint sources. Mission concepts for a 'monostructure' OAS instrument of about 30-m size are examined.

  1. Asymmetric synthesis of (-)-adaline.

    PubMed

    Itoh, Toshimasa; Yamazaki, Naoki; Kibayashi, Chihiro

    2002-07-25

    [reaction: see text] An enantioselective total synthesis of (-)-adaline has been achieved starting from a chiral 6,6-disubstituted piperidone derivative previously prepared by diastereoselective allylation of a chiral tricyclic N-acyl-N,O-acetal. The key steps include lithium ion-activated SN2-type alkynylation of the tricyclic N,O-acetal leading to exclusive formation of the (6S)-ethynylpiperidine and ring-closing olefin metathesis of the (2R,6S)-cis-2,6-dialkenylpiperidine for constructing the bridged azabicyclononane.

  2. Exploring and Implementing Participatory Action Synthesis

    ERIC Educational Resources Information Center

    Wimpenny, Katherine; Savin-Baden, Maggi

    2012-01-01

    This article presents participatory action synthesis as a new approach to qualitative synthesis which may be used to facilitate the promotion and use of qualitative research for policy and practice. The authors begin by outlining different forms of qualitative research synthesis and then present participatory action synthesis, a collaborative…

  3. Synthesis Gas Biorefinery.

    PubMed

    Dahmen, N; Henrich, E; Henrich, T

    2017-03-23

    Synthesis gas or syngas is an intermediate, which can be produced by gasification from a variety of carbonaceous feedstocks including biomass. Carbon monoxide and hydrogen, the main constituents of syngas, can be subjected to a broad range of chemical and microbial synthesis processes, leading to gaseous and liquid hydrocarbon fuels as well as to platform and fine chemicals. Gasification of solid biomass differs from coal gasification by chemical composition, heating value, ash behavior, and other technical and biomass related issues. By thermochemical pre-treatment of lignocellulose as the most abundant form of biomass, for example, by torrefaction or fast pyrolysis, energy dense fuels for gasification can be obtained, which can be used in the different types of gasifiers available today. A number of pilot and demonstration plants exist, giving evidence of the broad technology portfolio developed so far. Therefore, a syngas biorefinery is highly flexible in regard to feedstock and product options. However, the technology is complex and does not result in competitive production costs today. Added value can be generated by suitable integration of thermochemical, biochemical, and chemical processes.

  4. Oxygenates vs. synthesis gas

    SciTech Connect

    Kamil Klier; Richard G. Herman; Alessandra Beretta; Maria A. Burcham; Qun Sun; Yeping Cai; Biswanath Roy

    1999-04-01

    Methanol synthesis from H{sub 2}/CO has been carried out at 7.6 MPa over zirconia-supported copper catalysts. Catalysts with nominal compositions of 10/90 mol% and 30/70 mol% Cu/ZrO{sub 2} were used in this study. Additionally, a 3 mol% cesium-doped 10/90 catalyst was prepared to study the effect of doping with heavy alkali, and this promoter greatly increased the methanol productivity. The effects of CO{sub 2} addition, water injection, reaction temperature, and H{sub 2}/C0 ratio have been investigated. Both CO{sub 2} addition to the synthesis gas and cesium doping of the catalyst promoted methanol synthesis, while inhibiting the synthesis of dimethyl ether. Injection of water, however, was found to slightly suppress methanol and dimethyl ether formation while being converted to CO{sub 2} via the water gas shift reaction over these catalysts. There was no clear correlation between copper surface area and catalyst activity. Surface analysis of the tested samples revealed that copper tended to migrate and enrich the catalyst surface. The concept of employing a double-bed reactor with a pronounced temperature gradient to enhance higher alcohol synthesis was explored, and it was found that utilization of a Cs-promoted Cu/ZnO/Cr{sub 2}O{sub 3} catalyst as a first lower temperature bed and a Cs-promoted ZnO/Cr{sub 2}O{sub 3} catalyst as a second high-temperature bed significantly promoted the productivity of 2-methyl-1-propanol (isobutanol) from H{sub 2}/CO synthesis gas mixtures. While the conversion of CO to C{sub 2+} oxygenates over the double-bed configuration was comparable to that observed over the single Cu-based catalyst, major changes in the product distribution occurred by the coupling to the zinc chromite catalyst; that is, the productivity of the C{sub 1}-C{sub 3} alcohols decreased dramatically, and 2-methyl branched alcohols were selectively formed. The desirable methanol/2-methyl oxygenate molar ratios close to 1 were obtained in the present double

  5. Organic Synthesis in Space

    NASA Technical Reports Server (NTRS)

    Sandford, Scott A.; DeVincenzi, Donald (Technical Monitor)

    2002-01-01

    This talk will review our current understanding of the synthesis of organic molecules in space, with particular emphasis on the synthesis of those compounds that may be of prebiotic interest. The talk will address the possibility that molecules created in the interstellar medium may play a role in the origin and evolution of life on planetary surfaces. The various organic and volatile compounds that are now known or suspected to exist in a variety of space environments (stellar outflows, the diffuse interstellar medium, dense molecular clouds, protostellar nebulae, and planetesimal parent bodies in planetary systems) will be reviewed. This information comes largely from the combined applications of observational infrared and radio spectroscopy, laboratory astrophysical simulations, and theoretical astrochemistry. This will be followed by a discussion of the evidence, largely gathered from the laboratory isotopic study of extraterrestrial materials (meteorites and cosmic dust), that interstellar materials, including organics, can and do survive the transition from the interstellar space into forming stellar systems. Once there, some of this material can be delivered largely unaltered to planetary surfaces where it can play key roles in the origin and subsequent evolution of life.

  6. Synthesis of perfluoroalkylene dianilines

    NASA Technical Reports Server (NTRS)

    Paciorek, K. L.; Ito, T. I.; Harris, D. H.; Beechan, C. M.; Nakaham, J. H.; Kratzer, R. H.

    1981-01-01

    The objective of this contrast was to optimize and scale-up the synthesis of 2,2-bis(4-aminophenyl)-hexafluoropropane and 1,3-bis(4-aminophenyl)hexafluoropropane, as well as to explore avenues to other perfluoroalkyl-bridged dianilines. Routes other than Friedel-Crafts reaction leading to 2,2-bis(4-aminophenyl)hexafluoropropane were investigated. The processes utilizing bisphenol-AF were all unsuccessful; reactions aimed at the production of 4-(hexafluoro-2-halo-isopropyl)aniline from the hydroxyl intermediate failed to yield the desired products. Tailoring the conditions of the Friedel-Crafts reaction of 4-(hexafluoro-2-hydroxyisopropyl)aniline, aniline, and aluminum chloride by using hydrochloride salts and selecting optimum reagent ratios, reaction times, and temperature resulted in approx. 20% yield of pure crystallized 2,2-bis(4-aminophenyl)hexafluoropropane in 0.2 mole reaction batches. Yields up to approx. 40% were realized in small, approx. 0.01 mole, batches. The synthesis of 1,3-bis(4-aminophenyl)hexafluoropropane starting with perfluoroglutarimidine was reinvestigated. The yield of the 4-step reaction sequence giving 1,3-bis(4-acetamidophenyl)hexafluoropropane was raised to 44%. The yield of the subsequent hydrolysis process was improved by a factor of approx. 2. Approaches to prepare other perfluoroalkyl-bridged dianilines were unsuccessful. Reactions reported to proceed readily with trifluoromethyl substituents failed when longer chain perfluoroalkyl groups were employed.

  7. Graphene synthesis by ion implantation

    PubMed Central

    Garaj, Slaven; Hubbard, William; Golovchenko, J. A.

    2010-01-01

    We demonstrate an ion implantation method for large-scale synthesis of high quality graphene films with controllable thickness. Thermally annealing polycrystalline nickel substrates that have been ion implanted with carbon atoms results in the surface growth of graphene films whose average thickness is controlled by implantation dose. The graphene film quality, as probed with Raman and electrical measurements, is comparable to previously reported synthesis methods. The implantation synthesis method can be generalized to a variety of metallic substrates and growth temperatures, since it does not require a decomposition of chemical precursors or a solvation of carbon into the substrate. PMID:21124725

  8. Synthesis of Enantiomerically Pure Anthracyclinones

    NASA Astrophysics Data System (ADS)

    Achmatowicz, Osman; Szechner, Barbara

    The anthracycline antibiotics are among the most important clinical drugs used in the treatment of human cancer. The search for new agents with improved therapeutic efficacy and reduced cardiotoxicity stimulated considerable efforts in the synthesis of new analogues. Since the biological activity of anthracyclines depends on their natural absolute configuration, various strategies for the synthesis of enantiomerically pure anthracyclinones (aglycones) have been developed. They comprise: resolution of racemic intermediate, incorporation of a chiral fragment derived from natural and non-natural chiral pools, asymmetric synthesis with the use of a chiral auxiliary or a chiral reagent, and enantioselective catalysis. Synthetic advances towards enantiopure anthracyclinones reported over the last 17 years are reviewed.

  9. The prebiotic synthesis of oligonucleotides

    NASA Technical Reports Server (NTRS)

    Oro, J.; Stephen-Sherwood, E.

    1974-01-01

    This paper is primarily a review of recent developments in the abiotic synthesis of nucleotides, short chain oligonucleotides, and their mode of replication in solution. It also presents preliminary results from this laboratory on the prebiotic synthesis of thymidine oligodeoxynucleotides. A discussion, based on the physicochemical properties of RNA and DNA oligomers, relevant to the molecular evolution of these compounds leads to the tentative hypothesis that oligodeoxyribonucleotides of about 12 units may have been of sufficient length to initiate a self replicating coding system. Two models are suggested to account for the synthesis of high molecular weight oligomers using short chain templates and primers.

  10. Synthesis of biomedical tissue

    NASA Astrophysics Data System (ADS)

    Rolland, Jannick P.; Goon, Alexei A.; Clarkson, Eric; Yu, Liyun

    1998-04-01

    Image quality assessment in medical imaging requires realistic textured background that can be statistically characterized for the computation of model observers' performance. We present a modeling framework for the synthesis of texture as well as a statistical analysis of both sample and synthesized textures. The model employs a two-component image-decomposition consisting of a slowly, spatially varying mean-background and a residual texture image. Each component is synthesized independently. The technique is demonstrated using radiological breast tissue. For statistical characterization, we compute the two-point probability density functions for the real and synthesized breast tissue textures in order to provide a complete characterization and comparison of their second-order statistics. Similar computations for other textures yield further insight into the statistical properties of these types of random fields.

  11. Photocontrol of Anthocyanin Synthesis

    PubMed Central

    Ku, Ping-Kaung; Mancinelli, Alberto L.

    1972-01-01

    Red far red reversibility (phytochrome control) of anthocyanin synthesis can be easily demonstrated for the response induced by short (5 minutes) and relatively short (4 hours) irradiation. Red far red reversibility of the response induced by longer irradiations can be demonstrated by the use of cyclic irradiations alternating short exposures to red and far red light. The level of anthocyanin formed during the dark incubation period following exposure to light depends upon the duration of the irradiation and becomes proportionally smaller as the length of the irradiation increases. Production of anthocyanins under cyclic irradiations depends upon the total energy applied and upon the length of the dark interval between successive irradiations. The relative efficiencies of radiations in various spectral ranges change with changes in the length of the irradiations. PMID:16657927

  12. [Visual synthesis of speech].

    PubMed

    Blanco, Y; Villanueva, A; Cabeza, R

    2000-01-01

    The eyes can come to be the sole tool of communication for highly disabled patients. With the appropriate technology it is possible to successfully interpret eye movements, increasing the possibilities of patient communication with the use of speech synthesisers. A system of these characteristics will have to include a speech synthesiser, an interface for the user to construct the text and a method of gaze interpretation. In this way a situation will be achieved in which the user will manage the system solely with his eyes. This review sets out the state of the art of the three modules that make up a system of this type, and finally it introduces the speech synthesis system (Síntesis Visual del Habla [SiVHa]), which is being developed in the Public University of Navarra.

  13. Green chemistry for nanoparticle synthesis.

    PubMed

    Duan, Haohong; Wang, Dingsheng; Li, Yadong

    2015-08-21

    The application of the twelve principles of green chemistry in nanoparticle synthesis is a relatively new emerging issue concerning the sustainability. This field has received great attention in recent years due to its capability to design alternative, safer, energy efficient, and less toxic routes towards synthesis. These routes have been associated with the rational utilization of various substances in the nanoparticle preparations and synthetic methods, which have been broadly discussed in this tutorial review. This article is not meant to provide an exhaustive overview of green synthesis of nanoparticles, but to present several pivotal aspects of synthesis with environmental concerns, involving the selection and evaluation of nontoxic capping and reducing agents, the choice of innocuous solvents and the development of energy-efficient synthetic methods.

  14. Synthesis of Quaternary Heterocyclic Salts

    PubMed Central

    Winstead, Angela J.; Nyambura, Grace; Matthews, Rachael; Toney, Deveine; Oyaghire, Stanley

    2014-01-01

    The microwave synthesis of twenty quaternary ammonium salts is described. The syntheses feature comparable yields to conventional synthetic methods reported in the current literature with reduced reaction times and the absence of solvent or minimal solvent. PMID:24256924

  15. Instrument Synthesis and Analysis Laboratory

    NASA Technical Reports Server (NTRS)

    Wood, H. John

    2004-01-01

    The topics addressed in this viewgraph presentation include information on 1) Historic instruments at Goddard; 2) Integrated Design Capability at Goddard; 3) The Instrument Synthesis and Analysis Laboratory (ISAL).

  16. Vanillin Synthesis from 4-Hydroxybenzaldehyde

    ERIC Educational Resources Information Center

    Taber, Douglass F.; Patel, Shweta; Hambleton, Travis M.; Winkel, Emma E.

    2007-01-01

    A regioselective, safe and efficient method for the synthesis of vanillin from 4-hydroxybenzaldehyde is being described. The vanillin derived from the process is cheap and can be used as a flavor or in the paper industry.

  17. CLEAN CHEMICAL SYNTHESIS IN WATER

    EPA Science Inventory

    Newer green chemistry approach to accomplish chemical synthesis in water is summarized. Recent global developments pertaining to C-C bond forming reactions using metallic reagents and direct use of the renewable materials such as carbohydrates without derivatization are described...

  18. Concise asymmetric synthesis of (-)-sparteine.

    PubMed

    Hermet, Jean-Paul R; McGrath, Matthew J; O'Brien, Peter; Porter, David W; Gilday, John

    2004-08-21

    A six-step asymmetric synthesis of natural (-)-sparteine from ethyl 7-iodohept-2-enoate is reported, involving a connective Michael addition of an amino ester-derived enolate to an alpha,beta-unsaturated amino ester.

  19. Borinic acid catalysed peptide synthesis.

    PubMed

    El Dine, Tharwat Mohy; Rouden, Jacques; Blanchet, Jérôme

    2015-11-18

    The catalytic synthesis of peptides is a major challenge in the modern organic chemistry hindered by the well-established use of stoichiometric coupling reagents. Herein, we describe for the first time that borinic acid is able to catalyse this reaction under mild conditions with an improved activity compared to our recently developed thiophene-based boronic acid. This catalyst is particularly efficient for peptide bond synthesis affording dipeptides in good yields without detectable racemization.

  20. Diamond Synthesis Employing Nanoparticle Seeds

    NASA Technical Reports Server (NTRS)

    Uppireddi, Kishore (Inventor); Morell, Gerardo (Inventor); Weiner, Brad R. (Inventor)

    2014-01-01

    Iron nanoparticles were employed to induce the synthesis of diamond on molybdenum, silicon, and quartz substrates. Diamond films were grown using conventional conditions for diamond synthesis by hot filament chemical vapor deposition, except that dispersed iron oxide nanoparticles replaced the seeding. This approach to diamond induction can be combined with dip pen nanolithography for the selective deposition of diamond and diamond patterning while avoiding surface damage associated to diamond-seeding methods.

  1. Exploiting Constraints in Design Synthesis

    DTIC Science & Technology

    1987-04-01

    policy for a state. Herbert Simon , The Science of Design 1.1 Overview Robot planning, genetic synthesis, chemical synthesis, circuit design, and...Sanders Peirce (1839-1914) [36] used "abduction" to mean the "creative formulation of statistical hypotheses" (Encyclopedia of Philosophy, page 4-176... theory be part of the design. In short, there is a certain threshold of detail that is agreed upon by the designer and implementor as being primitively

  2. Selective isoparaffin synthesis from naphtha

    SciTech Connect

    Bogdan, P.L.; Lawson, R.J.; Sachtler, J.W.A.

    1993-08-10

    A process combination is described for selectively upgrading a naphtha feedstock to obtain lower-boiling hydrocarbons having an increased content of branched-chain paraffins comprising the steps of: (a) contacting the naphtha feedstock in a hydrogenation zone with a hydrogenation catalyst comprising a platinum-group metal component and a refractory inorganic oxide in the presence of hydrogen at a pressure of from about 10 to 100 atmospheres, a temperature of at least 30 C, and a liquid hourly space velocity of from about 1 to 8 to produce a saturated intermediate; (b) contacting the saturated intermediate without heating in a selective-isoparaffin-synthesis zone at a pressure of from about 10 to 100 atmospheres, a temperature of between about 50 and 350 C, and a liquid hourly space velocity of between about 0.5 and 20 with a solid acid selective isoparaffin-synthesis catalyst comprising a combination of a platinum-group metal component on a chlorided inorganic-oxide support with a Friedel-Crafts metal halide in the presence of hydrogen, recovering synthesis product containing butanes and pentanes, and separating the synthesis product to obtain an isobutane concentrate, a light synthesis product comprising pentanes and a heavy synthesis product comprising C[sub 7] and C[sub 8] hydrocarbons; (c) dehydrogenating at least a portion of the isobutane concentrate in a dehydrogenation zone at dehydrogenation conditions using a dehydrogenation catalyst and recovering an isobutene-containing stream; (d) contacting at least a portion of the isobutene-containing stream with an alcohol in an etherification zone at etherification conditions to obtain an ether and a hydrocarbon raffinate; (e) contacting the heavy synthesis product in a reforming zone at reforming conditions using a reforming catalyst to obtain a reformate; and, (f) blending a gasoline component comprising at least a portion of each of the light synthesis product, ether and reformate.

  3. Albumin synthesis in surgical patients.

    PubMed

    Hülshoff, Ansgar; Schricker, Thomas; Elgendy, Hamed; Hatzakorzian, Roupen; Lattermann, Ralph

    2013-05-01

    Albumin plasma concentrations are being used as indicators of nutritional status and hepatic function based on the assumption that plasma levels reflect the rate of albumin synthesis. However, it has been shown that albumin levels are not reliable markers of albumin synthesis under a variety of clinical conditions including inflammation, malnutrition, diabetes mellitus, liver disease, and surgical tissue trauma. To date, only a few studies have measured albumin synthesis in surgical and critically ill patients. This review summarizes the findings from these studies, which used different tracer methodology in various surgical or critically ill patient populations. The results indicate that the fractional synthesis rate of albumin appears to decrease during surgery, followed by an increase during the postoperative phase. In the early postoperative phase, albumin fractional synthesis rate can be stimulated by perioperative nutrition, if enough amino acids are being provided and if nutrition is being initiated before the operation. The physiologic meaning of albumin synthesis after surgery, however, still needs to be further clarified.

  4. Synthesis of nanostructured polyaniline

    NASA Astrophysics Data System (ADS)

    Surwade, Sumedh P.

    The organization of my thesis is as follows: (a) Chapter III describes the synthesis of bulk quantities of polyaniline nanofibers in one step using a simple and versatile high ionic strength aqueous system (HCl/NaCl) that permits the use of pure H2O2 as a mild oxidant without any added metal or enzyme catalyst. Polyaniline nanofibers obtained are highly conducting, sigma˜1--5 S/cm, and spectroscopically similar to conventional polyaniline synthesized using stronger oxidants. The synthesis method is further extended to the synthesis of oligoanilines of controlled molecular weight, e.g., aniline tetramer, octamer, and hexadecamer. Microns long tetramer nanofibers are synthesized using this method. (b) Chapter IV describes the mechanism of nanofiber formation in polyaniline. It is proposed that the surfaces such as the walls of the reaction vessel and/or intentionally added surfaces play a dramatic role in the evolution of nanofibrillar morphology. Nucleation sites on surfaces promote the accumulation of aniline dimer that reacts further to yield aniline tetramer, which (surprisingly) is entirely in form of nanofibers and whose morphology is transcribed to the bulk by a double heterogeneous nucleation mechanism. This unexpected phenomenon could form the basis of nanofiber formation in all classes of precipitation polymerization systems. (c) Chapter V is the mechanistic study on the formation of oligoanilines during the chemical oxidation of aniline in weakly acidic, neutral or basic media using peroxydisulfate oxidant. It is proposed that the reaction proceeds via the intermediacy of benzoquinone monoimine that is formed as a result of a Boyland-Sims rearrangement of aniline. The initial role of peroxydisulfate is to provide a pathway for the formation of benzoquinone monoimine intermediate that is followed by a conjugate Michael-type addition reaction with aniline or sulfated anilines. The products isolated in pH 2.5--10.0 buffers are intermediate species at various

  5. Accuracy of results with NASTRAN modal synthesis

    NASA Technical Reports Server (NTRS)

    Herting, D. N.

    1978-01-01

    A new method for component mode synthesis was developed for installation in NASTRAN level 17.5. Results obtained from the new method are presented, and these results are compared with existing modal synthesis methods.

  6. Control Augmented Structural Synthesis

    NASA Technical Reports Server (NTRS)

    Lust, Robert V.; Schmit, Lucien A.

    1988-01-01

    A methodology for control augmented structural synthesis is proposed for a class of structures which can be modeled as an assemblage of frame and/or truss elements. It is assumed that both the plant (structure) and the active control system dynamics can be adequately represented with a linear model. The structural sizing variables, active control system feedback gains and nonstructural lumped masses are treated simultaneously as independent design variables. Design constraints are imposed on static and dynamic displacements, static stresses, actuator forces and natural frequencies to ensure acceptable system behavior. Multiple static and dynamic loading conditions are considered. Side constraints imposed on the design variables protect against the generation of unrealizable designs. While the proposed approach is fundamentally more general, here the methodology is developed and demonstrated for the case where: (1) the dynamic loading is harmonic and thus the steady state response is of primary interest; (2) direct output feedback is used for the control system model; and (3) the actuators and sensors are collocated.

  7. Microbial Engineering for Aldehyde Synthesis

    PubMed Central

    Kunjapur, Aditya M.

    2015-01-01

    Aldehydes are a class of chemicals with many industrial uses. Several aldehydes are responsible for flavors and fragrances present in plants, but aldehydes are not known to accumulate in most natural microorganisms. In many cases, microbial production of aldehydes presents an attractive alternative to extraction from plants or chemical synthesis. During the past 2 decades, a variety of aldehyde biosynthetic enzymes have undergone detailed characterization. Although metabolic pathways that result in alcohol synthesis via aldehyde intermediates were long known, only recent investigations in model microbes such as Escherichia coli have succeeded in minimizing the rapid endogenous conversion of aldehydes into their corresponding alcohols. Such efforts have provided a foundation for microbial aldehyde synthesis and broader utilization of aldehydes as intermediates for other synthetically challenging biochemical classes. However, aldehyde toxicity imposes a practical limit on achievable aldehyde titers and remains an issue of academic and commercial interest. In this minireview, we summarize published efforts of microbial engineering for aldehyde synthesis, with an emphasis on de novo synthesis, engineered aldehyde accumulation in E. coli, and the challenge of aldehyde toxicity. PMID:25576610

  8. Collaboration and Productivity in Scientific Synthesis

    ERIC Educational Resources Information Center

    Hampton, Stephanie E.; Parker, John N.

    2011-01-01

    Scientific synthesis has transformed ecological research and presents opportunities for advancements across the sciences; to date, however, little is known about the antecedents of success in synthesis. Building on findings from 10 years of detailed research on social interactions in synthesis groups at the National Center for Ecological Analysis…

  9. The modern synthesis, Ronald Fisher and creationism.

    PubMed

    Leigh

    1999-12-01

    The 'modern evolutionary synthesis' convinced most biologists that natural selection was the only directive influence on adaptive evolution. Today, however, dissatisfaction with the synthesis is widespread, and creationists and antidarwinians are multiplying. The central problem with the synthesis is its failure to show (or to provide distinct signs) that natural selection of random mutations could account for observed levels of adaptation.

  10. Concepts in Biochemistry: Chemical Synthesis of DNA.

    ERIC Educational Resources Information Center

    Caruthers, Marvin H.

    1989-01-01

    Outlines the chemistry of the rapid synthesis of relatively large DNA fragments (100-200 monomers each) with yields exceeding 99 percent per coupling. DNA synthesis methodologies are outlined and a polymer-supported synthesis of DNA using deoxynucleoside phosphoramidites is described with structural formulas. (YP)

  11. Maitotoxin: An Inspiration for Synthesis

    PubMed Central

    Aversa, Robert J.

    2011-01-01

    Maitotoxin holds a special place in the annals of natural products chemistry as the largest and most toxic secondary metabolite known to date. Its fascinating, ladder-like, polyether molecular structure and diverse spectrum of biological activities elicited keen interest from chemists and biologists who recognized its uniqueness and potential as a probe and inspiration for research in chemistry and biology. Synthetic studies in the area benefited from methodologies and strategies that were developed as part of chemical synthesis programs directed toward the total synthesis of some of the less complex members of the polyether marine biotoxin class, of which maitotoxin is the flagship. This account focuses on progress made in the authors’ laboratories in the synthesis of large maitotoxin domains with emphasis on methodology development, strategy design, and structural comparisons of the synthesized molecules with the corresponding regions of the natural product. The article concludes with an overview of maitotoxin’s biological profile and future perspectives. PMID:21709816

  12. Flavivirus RNA Synthesis in vitro

    PubMed Central

    Padmanabhan, Radhakrishnan; Takhampunya, Ratree; Teramoto, Tadahisa; Choi, Kyung H.

    2015-01-01

    Summary Establishment of in vitro systems to study mechanisms of RNA synthesis for positive strand RNA viruses have been very useful in the past and have shed light on the composition of protein and RNA components, optimum conditions, the nature of the products formed, cis-acting RNA elements and trans-acting protein factors required for efficient synthesis. In this review, we summarize our current understanding regarding the requirements for flavivirus RNA synthesis in vitro. We describe details of reaction conditions, the specificity of template used by either the multi-component membrane-bound viral replicase complex or by purified, recombinant RNA-dependent RNA polymerase. We also discuss future perspectives to extend the boundaries of our knowledge. PMID:26272247

  13. CHEMICAL SYNTHESIS OF GLYCOSYLPHOSPHATIDYLINOSITOL ANCHORS

    PubMed Central

    Swarts, Benjamin M.; Guo, Zhongwu

    2013-01-01

    Many eukaryotic cell-surface proteins and glycoproteins are anchored to the plasma membrane by glycosylphosphatidylinositols (GPIs), a family of glycolipids that are post-translationally attached to proteins at their C-termini. GPIs and GPI-anchored proteins play important roles in many biological and pathological events, such as cell recognition and adhesion, signal transduction, host defense, and acting as receptors for viruses and toxins. Chemical synthesis of structurally defined GPI anchors and GPI derivatives is a necessary step toward understanding the properties and functions of these molecules in biological systems and exploring their potential therapeutic applications. In the first part of this comprehensive article on the chemical synthesis of GPIs, classic syntheses of naturally occurring GPI anchors from protozoan parasites, yeast, and mammals are covered. The second part of the article focuses on recent diversity-oriented strategies for the synthesis of GPI anchors containing unsaturated lipids, “click chemistry” tags, and highly branched and modified structures. PMID:22794184

  14. Erythropoietin Derived by Chemical Synthesis

    PubMed Central

    Shieh, Jae-Hung; Peguero, Elizabeth; Hendrickson, Ronald; Moore, Malcolm A. S.; Danishefsky, Samuel J.

    2014-01-01

    Erythropoietin is a signaling glycoprotein that controls the fundamental process of erythropoiesis, orchestrating the production and maintenance of red blood cells. As administrated clinically, erythropoietin has a polypeptide backbone with complex dishomogeneity in its carbohydrate domains. Here we describe the total synthesis of homogeneous erythropoietin with consensus carbohydrate domains incorporated at all of the native glycosylation sites. The oligosaccharide sectors were built by total synthesis and attached stereospecifically to peptidyl fragments of the wild-type primary sequence, themselves obtained by solid-phase peptide synthesis. The glycopeptidyl constructs were joined by chemical ligation, followed by metal-free dethiylation, and subsequently folded. This homogeneous erythropoietin glycosylated at the three wild-type aspartates with N-linked high-mannose sialic acid–containing oligosaccharides and O-linked glycophorin exhibits Procrit-level in vivo activity in mice. PMID:24337294

  15. Sterol Synthesis in Diverse Bacteria

    PubMed Central

    Wei, Jeremy H.; Yin, Xinchi; Welander, Paula V.

    2016-01-01

    Sterols are essential components of eukaryotic cells whose biosynthesis and function has been studied extensively. Sterols are also recognized as the diagenetic precursors of steranes preserved in sedimentary rocks where they can function as geological proxies for eukaryotic organisms and/or aerobic metabolisms and environments. However, production of these lipids is not restricted to the eukaryotic domain as a few bacterial species also synthesize sterols. Phylogenomic studies have identified genes encoding homologs of sterol biosynthesis proteins in the genomes of several additional species, indicating that sterol production may be more widespread in the bacterial domain than previously thought. Although the occurrence of sterol synthesis genes in a genome indicates the potential for sterol production, it provides neither conclusive evidence of sterol synthesis nor information about the composition and abundance of basic and modified sterols that are actually being produced. Here, we coupled bioinformatics with lipid analyses to investigate the scope of bacterial sterol production. We identified oxidosqualene cyclase (Osc), which catalyzes the initial cyclization of oxidosqualene to the basic sterol structure, in 34 bacterial genomes from five phyla (Bacteroidetes, Cyanobacteria, Planctomycetes, Proteobacteria, and Verrucomicrobia) and in 176 metagenomes. Our data indicate that bacterial sterol synthesis likely occurs in diverse organisms and environments and also provides evidence that there are as yet uncultured groups of bacterial sterol producers. Phylogenetic analysis of bacterial and eukaryotic Osc sequences confirmed a complex evolutionary history of sterol synthesis in this domain. Finally, we characterized the lipids produced by Osc-containing bacteria and found that we could generally predict the ability to synthesize sterols. However, predicting the final modified sterol based on our current knowledge of sterol synthesis was difficult. Some bacteria

  16. Synthesis metal nanoparticle

    DOEpatents

    Bunge, Scott D.; Boyle, Timothy J.

    2005-08-16

    A method for providing an anhydrous route for the synthesis of amine capped coinage-metal (copper, silver, and gold) nanoparticles (NPs) using the coinage-metal mesityl (mesityl=C.sub.6 H.sub.2 (CH.sub.3).sub.3 -2,4,6) derivatives. In this method, a solution of (Cu(C.sub.6 H.sub.2 (CH.sub.3).sub.3).sub.5, (Ag(C.sub.6 H.sub.2 (CH.sub.3).sub.3).sub.4, or (Au(C.sub.6 H.sub.2 (CH.sub.3).sub.3).sub.5 is dissolved in a coordinating solvent, such as a primary, secondary, or tertiary amine; primary, secondary, or tertiary phosphine, or alkyl thiol, to produce a mesityl precursor solution. This solution is subsequently injected into an organic solvent that is heated to a temperature greater than approximately 100.degree. C. After washing with an organic solvent, such as an alcohol (including methanol, ethanol, propanol, and higher molecular-weight alcohols), oxide free coinage NP are prepared that could be extracted with a solvent, such as an aromatic solvent (including, for example, toluene, benzene, and pyridine) or an alkane (including, for example, pentane, hexane, and heptane). Characterization by UV-Vis spectroscopy and transmission electron microscopy showed that the NPs were approximately 9.2.+-.2.3 nm in size for Cu.degree., (no surface oxide present), approximately 8.5.+-.1.1 nm Ag.degree. spheres, and approximately 8-80 nm for Au.degree..

  17. A sustainable catalytic pyrrole synthesis

    NASA Astrophysics Data System (ADS)

    Michlik, Stefan; Kempe, Rhett

    2013-02-01

    The pyrrole heterocycle is a prominent chemical motif and is found widely in natural products, drugs, catalysts and advanced materials. Here we introduce a sustainable iridium-catalysed pyrrole synthesis in which secondary alcohols and amino alcohols are deoxygenated and linked selectively via the formation of C-N and C-C bonds. Two equivalents of hydrogen gas are eliminated in the course of the reaction, and alcohols based entirely on renewable resources can be used as starting materials. The catalytic synthesis protocol tolerates a large variety of functional groups, which includes olefins, chlorides, bromides, organometallic moieties, amines and hydroxyl groups. We have developed a catalyst that operates efficiently under mild conditions.

  18. Total Synthesis of (+)-Superstolide A

    PubMed Central

    Tortosa, Mariola; Yakelis, Neal A.; Roush, William R.

    2009-01-01

    A convergent and highly stereocontrolled total synthesis of the cytotoxic macrolide (+)-superstolide A is described. Key features of this synthesis include the use of bimetallic linchpin 36b for uniting the C(1)-C(15) (43) and the C(20)-C(27) (38) fragments of the natural product, a late-stage Suzuki macrocyclization of 49, and a highly diastereoselective transannular Diels-Alder reaction of macrocyclic octanene 4. In contrast, the intramolecular Diels-Alder reaction of pentaenal 5 provided the desired cycloadduct with lower stereoselectivity (6:1:1). PMID:18956845

  19. Quinazoline derivatives: synthesis and bioactivities

    PubMed Central

    2013-01-01

    Owing to the significant biological activities, quinazoline derivatives have drawn more and more attention in the synthesis and bioactivities research. This review summarizes the recent advances in the synthesis and biological activities investigations of quinazoline derivatives. According to the main method the authors adopted in their research design, those synthetic methods were divided into five main classifications, including Aza-reaction, Microwave-assisted reaction, Metal-mediated reaction, Ultrasound-promoted reaction and Phase-transfer catalysis reaction. The biological activities of the synthesized quinazoline derivatives also are discussed. PMID:23731671

  20. Aiming for the ideal synthesis.

    PubMed

    Gaich, Tanja; Baran, Phil S

    2010-07-16

    The field of total synthesis has a rich history and a vibrant future. Landmark advances and revolutionary strides in the logic of synthesis have put the practicing chemist in the enviable position of being able to create nearly any molecule with enough time and effort. The stage is now set for organic chemists to aim for "ideality" in the way molecules are synthesized. This perspective presents a simple and informative definition of "ideality" and demonstrates its use during the self-evaluation of several syntheses from our laboratory.

  1. Stereocontrolled total synthesis of (+)-vincristine

    PubMed Central

    Kuboyama, Takeshi; Yokoshima, Satoshi; Tokuyama, Hidetoshi; Fukuyama, Tohru

    2004-01-01

    An efficient total synthesis of (+)-vincristine has been accomplished through a stereoselective coupling of demethylvindoline and the eleven-membered carbomethoxyverbanamine presursor. Demethylvindoline was prepared by oxidation of 17-hydroxy-11-methoxytabersonine, followed by regioselective acetylation with mixed anhydride method. Although an initial attempt of coupling by using demethylvindoline formamide was not successful and resulted in recovery of the starting compounds, the reaction using demethylvindoline took place smoothly to furnish the desired bisindole product with the correct stereochemistry at C18′. After formation of the piperidine ring by sequential removal of the protective groups and intramolecular nucleophilic cyclization, the total synthesis of vincristine was completed by formylation of N1. PMID:15141084

  2. Heterogeneous photocatalysts in organic synthesis

    NASA Astrophysics Data System (ADS)

    Cherevatskaya, M.; König, B.

    2014-03-01

    The review deals with the application of inorganic semiconductors in organic synthesis. Although the majority of reported reactions still aim at the photocatalytic decomposition of organic compounds, the number of examples in synthetic applications is growing. The principal mechanisms of heterogeneous semiconductor photocatalysis are considered and examples illustrating the use of inorganic semiconductors in organic synthesis are given. The discussion is arranged according to the required excitation wavelength (UV or visible light) and to the new bond that is formed (carbon-carbon or carbon-heteroatom bond). The bibliography includes 47 references.

  3. Synthesis of Illudinine from Dimedone.

    PubMed

    Morrison, Alec E; Hoang, Tung T; Birepinte, Mélodie; Dudley, Gregory B

    2017-02-17

    A total synthesis of the illudalane sesquiterpene illudinine was realized in eight steps and 14% overall yield from commercially available dimedone. The approach features tandem fragmentation/Knoevenagel-type condensation and microwave-assisted oxidative cycloisomerization to establish the isoquinoline core. Completion of the synthesis involves a recently reported cascade SNAr/Lossen rearrangement on a densely functionalized aryl bromide and an optimized procedure for O-methylation of 8-hydroxyisoquinolines. The oxidative cycloisomerization proceeds by way of a novel inverse-demand intramolecular dehydro-Diels-Alder cycloaddition, which has a potentially broader appeal for preparing substituted isoquinolines.

  4. Optica aperture synthesis

    NASA Astrophysics Data System (ADS)

    van der Avoort, Casper

    2006-05-01

    Optical long baseline stellar interferometry is an observational technique in astronomy that already exists for over a century, but is truly blooming during the last decades. The undoubted value of stellar interferometry as a technique to measure stellar parameters beyond the classical resolution limit is more and more spreading to the regime of synthesis imaging. With optical aperture synthesis imaging, the measurement of parameters is extended to the reconstruction of high resolution stellar images. A number of optical telescope arrays for synthesis imaging are operational on Earth, while space-based telescope arrays are being designed. For all imaging arrays, the combination of the light collected by the telescopes in the array can be performed in a number of ways. In this thesis, methods are introduced to model these methods of beam combination and compare their effectiveness in the generation of data to be used to reconstruct the image of a stellar object. One of these methods of beam combination is to be applied in a future space telescope. The European Space Agency is developing a mission that can valuably be extended with an imaging beam combiner. This mission is labeled Darwin, as its main goal is to provide information on the origin of life. The primary objective is the detection of planets around nearby stars - called exoplanets- and more precisely, Earth-like exoplanets. This detection is based on a signal, rather than an image. With an imaging mode, designed as described in this thesis, Darwin can make images of, for example, the planetary system to which the detected exoplanet belongs or, as another example, of the dust disk around a star out of which planets form. Such images will greatly contribute to the understanding of the formation of our own planetary system and of how and when life became possible on Earth. The comparison of beam combination methods for interferometric imaging occupies most of the pages of this thesis. Additional chapters will

  5. Plant mediated green synthesis: modified approaches.

    PubMed

    Das, Ratul Kumar; Brar, Satinder Kaur

    2013-11-07

    Plant mediated green synthesis of different metallic nanoparticles has emerged as one of the options for implementation of green chemistry principles, and successfully made an important contribution towards green nanotechnology. However, beyond the synthesis and application aspects, the science of green synthesis has carried some wrong perceptions in an unforeseen fashion. In this review, some of the key issues related to the green synthesis of metallic nanoparticles employing plants as reducing/capping agents have been addressed. Random selection of plants and its overall impact on the different aspects of green synthesis have been discussed. Emphasis is given to the setting of some standard selection criteria to be adopted for selecting a plant for use in green synthesis. How selection of a plant can positively or negatively influence both procedure and products of a green synthesis process is the prime concern of this article. In addition to selection, the key issue of biocompatibility associated with green synthesized metallic nanoparticles has been considered. Both selection of plant and biocompatibility were reconsidered for their minute details in terms of synthesis, analysis and data interpretation in the green synthesis approach. The key factors capable of fine tuning the core meaning of "green" in the synthesis of any metallic nanoparticles were taken into consideration. This article is an effort towards keeping the core meaning of green synthesis.

  6. The Gabriel Synthesis of Benzylamine

    ERIC Educational Resources Information Center

    Nigh, W. G.

    1975-01-01

    Describes an undergraduate organic chemistry laboratory experiment which utilizes the Gabriel Synthesis to demonstrate the acidity of imides and to provide an example of nucleophilic substitution reactions. The experiment also demonstrates the laboratory techniques involved in simple and steam distillation, filtration, extraction, and…

  7. Catalysis and prebiotic RNA synthesis

    NASA Technical Reports Server (NTRS)

    Ferris, James P.

    1993-01-01

    The essential role of catalysis for the origins of life is discussed. The status of the prebiotic synthesis of 2',5'- and 3'5'-linked oligomers of RNA is reviewed. Examples of the role of metal ion and mineral catalysis in RNA oligomer formation are discussed.

  8. 3-Ketoesters by Malonic Synthesis.

    ERIC Educational Resources Information Center

    Pollet, Patrick L.

    1983-01-01

    Discusses the acylation version of malonic synthesis of three-ketoesters. Includes advantages of this method over other methodologies including a final selective removal of the "activating" ester function in such mild conditions that most of the organic functions may survive. (JN)

  9. Green chemistry for chemical synthesis

    PubMed Central

    Li, Chao-Jun; Trost, Barry M.

    2008-01-01

    Green chemistry for chemical synthesis addresses our future challenges in working with chemical processes and products by inventing novel reactions that can maximize the desired products and minimize by-products, designing new synthetic schemes and apparati that can simplify operations in chemical productions, and seeking greener solvents that are inherently environmentally and ecologically benign. PMID:18768813

  10. Chronology of a Difficult Synthesis

    ERIC Educational Resources Information Center

    Menger, Fredric M.; Sorrells, Jennifer L.

    2009-01-01

    This article describes a short synthesis and many of the difficulties experienced while carrying it out (e.g., low yields, impurities, racemization, nonrepeatable literature preps, etc.). As such, students will be educated in aspects of synthetic organic chemistry that are often down-played, or even not mentioned, in published syntheses. (Contains…

  11. IN SEARCH OF A SYNTHESIS.

    ERIC Educational Resources Information Center

    HAWLEY, D.C.

    LANGUAGE INSTRUCTION SHOULD BE A SYNTHESIS OF THE BEST OF ALL METHODS. NO METHODOLOGY OR COMBINATION OF METHODOLOGIES WILL CHANGE THE FACT THAT LEARNING ANOTHER LANGUAGE IS THE ACQUISITION OF A COMPLEX AND DIFFICULT SKILL AND CAN BE ACCOMPLISHED ONLY WITH A GREAT DEAL OF TIME AND WORK ON THE PART OF BOTH TEACHER AND STUDENT. HOWEVER, IF, WITH THE…

  12. Synthesis of nanosized sodium titanates

    DOEpatents

    Hobbs, David T.; Taylor-Pashow, Kathryn M. L.; Elvington, Mark C.

    2015-09-29

    Methods directed to the synthesis and peroxide-modification of nanosized monosodium titanate are described. Methods include combination of reactants at a low concentration to a solution including a nonionic surfactant. The nanosized monosodium titanate can exhibit high selectivity for sorbing various metallic ions.

  13. Synthesis of a symmetrical dithiirane

    SciTech Connect

    Allakverdiev, M.A.; Farzaliev, V.M.; Mamedov, C.I.

    1986-04-01

    The reaction of p-xylene with epichlorohydrin in the presence of aluminum chloride gave 1,4-dimethyl-2,5-bis(1-chloro-2-hydroxypropyl) benzene, which serves as the starting compound for the synthesis of the corresponding symmetrical dithiirane.

  14. Robust Face Sketch Style Synthesis.

    PubMed

    Shengchuan Zhang; Xinbo Gao; Nannan Wang; Jie Li

    2016-01-01

    Heterogeneous image conversion is a critical issue in many computer vision tasks, among which example-based face sketch style synthesis provides a convenient way to make artistic effects for photos. However, existing face sketch style synthesis methods generate stylistic sketches depending on many photo-sketch pairs. This requirement limits the generalization ability of these methods to produce arbitrarily stylistic sketches. To handle such a drawback, we propose a robust face sketch style synthesis method, which can convert photos to arbitrarily stylistic sketches based on only one corresponding template sketch. In the proposed method, a sparse representation-based greedy search strategy is first applied to estimate an initial sketch. Then, multi-scale features and Euclidean distance are employed to select candidate image patches from the initial estimated sketch and the template sketch. In order to further refine the obtained candidate image patches, a multi-feature-based optimization model is introduced. Finally, by assembling the refined candidate image patches, the completed face sketch is obtained. To further enhance the quality of synthesized sketches, a cascaded regression strategy is adopted. Compared with the state-of-the-art face sketch synthesis methods, experimental results on several commonly used face sketch databases and celebrity photos demonstrate the effectiveness of the proposed method.

  15. Analysis and synthesis of laughter

    NASA Astrophysics Data System (ADS)

    Sundaram, Shiva; Narayanan, Shrikanth

    2004-10-01

    There is much enthusiasm in the text-to-speech community for synthesis of emotional and natural speech. One idea being proposed is to include emotion dependent paralinguistic cues during synthesis to convey emotions effectively. This requires modeling and synthesis techniques of various cues for different emotions. Motivated by this, a technique to synthesize human laughter is proposed. Laughter is a complex mechanism of expression and has high variability in terms of types and usage in human-human communication. People have their own characteristic way of laughing. Laughter can be seen as a controlled/uncontrolled physiological process of a person resulting from an initial excitation in context. A parametric model based on damped simple harmonic motion to effectively capture these diversities and also maintain the individuals characteristics is developed here. Limited laughter/speech data from actual humans and synthesis ease are the constraints imposed on the accuracy of the model. Analysis techniques are also developed to determine the parameters of the model for a given individual or laughter type. Finally, the effectiveness of the model to capture the individual characteristics and naturalness compared to real human laughter has been analyzed. Through this the factors involved in individual human laughter and their importance can be better understood.

  16. Steganography using reversible texture synthesis.

    PubMed

    Wu, Kuo-Chen; Wang, Chung-Ming

    2015-01-01

    We propose a novel approach for steganography using a reversible texture synthesis. A texture synthesis process resamples a smaller texture image, which synthesizes a new texture image with a similar local appearance and an arbitrary size. We weave the texture synthesis process into steganography to conceal secret messages. In contrast to using an existing cover image to hide messages, our algorithm conceals the source texture image and embeds secret messages through the process of texture synthesis. This allows us to extract the secret messages and source texture from a stego synthetic texture. Our approach offers three distinct advantages. First, our scheme offers the embedding capacity that is proportional to the size of the stego texture image. Second, a steganalytic algorithm is not likely to defeat our steganographic approach. Third, the reversible capability inherited from our scheme provides functionality, which allows recovery of the source texture. Experimental results have verified that our proposed algorithm can provide various numbers of embedding capacities, produce a visually plausible texture images, and recover the source texture.

  17. Organic chemistry: Streamlining drug synthesis

    NASA Astrophysics Data System (ADS)

    Hawkins, Joel M.

    2015-04-01

    Drug manufacture can benefit from flow synthesis, in which raw materials are fed into a sequence of reactors, producing the drug as a continuous output. A flow strategy that capitalizes on solid catalysts has now been realized. See Letter p.329

  18. CHEMICAL SYNTHESIS & TRANSFORMATIONS USING MICROWAVES

    EPA Science Inventory

    A historical account of the utility of microwaves in a variety of chemical synthesis applications will be presented, including a solvent-free strategy that involves microwave (MW) exposure of neat reactants (undiluted) catalyzed by the surfaces of recyclable mineral supports such...

  19. Enzymatic synthesis of prebiotic oligosaccharides.

    PubMed

    Rabelo, Maria C; Honorato, Talita L; Gonçalves, Luciana R B; Pinto, Gustavo A S; Rodrigues, Sueli

    2006-04-01

    Prebiotic oligosaccharides are nondigestible carbohydrates that can be obtained by enzymatic synthesis. Glucosyltransferases can be used to produce these carbohydrates through an acceptor reaction synthesis. When maltose is the acceptor a trisaccharide composed of one maltose unit and one glucose unit linked by an alpha-1,6-glycosidic bond (panose) is obtained as the primer product of the dextransucrase acceptor reaction. In this work, panose enzymatic synthesis was evaluated by a central composite experimental design in which maltose and sucrose concentration were varied in a wide range of maltose/sucrose ratios in a batch reactor system. A partially purified enzyme was used in order to reduce the process costs, because enzyme purification is one of the most expensive steps in enzymatic synthesis. Even using high maltose/sucrose ratios, dextran and higher-oligosaccharide formation were not avoided. The results showed that intermediate concentrations of sucrose and high maltose concentration resulted in high panose productivity with low dextran and higher-oligosaccharide productivity.

  20. Sulfur monochloride in organic synthesis

    NASA Astrophysics Data System (ADS)

    Konstantinova, L. S.; Rakitin, O. A.

    2014-03-01

    The data on the reactivity of sulfur monochloride published in the past 15 years have been reviewed and systematized. The review focuses on the synthesis of acyclic and heterocyclic compounds with the use of S2Cl2. The bibliography includes 154 references.

  1. Total synthesis of (-)-depyranoversicolamide B.

    PubMed

    Qin, Wen-Fang; Xiao, T; Zhang, D; Deng, Lin-Feng; Wang, Y; Qin, Y

    2015-11-18

    Starting from easily prepared (R)-C3-isoprenylated pyrroloindoline, the C3-isoprenylated indolyl diketopiperazine is prepared by an efficient reductive opening of the pyrrolo ring, and undergoes biomimetic Diels-Alder reaction to generate an anti-adduct as a sole stereoisomer. Oxidation of the indoline moiety to oxindole completes the synthesis of (-)-depyranoversicolamide B.

  2. Insolubilized enzymes for food synthesis

    NASA Technical Reports Server (NTRS)

    Marshall, D. L.

    1972-01-01

    Cellulose matrix with numerous enzyme-coated silica particles of colloidal size permanently bound at various sites within matrix was produced that has high activity and possesses requisite physical characteristics for filtration or column operations. Product also allows coupling step in synthesis of edible food to proceed under mild conditions.

  3. Synthesis of noble metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Bahadory, Mozhgan

    Improved methods were developed for the synthesis of noble metal nanoparticles. Laboratory experiments were designed for introducing of nanotechnology into the undergraduate curriculum. An optimal set of conditions for the synthesis of clear yellow colloidal silver was investigated. Silver nanoparticles were obtained by borohydride reduction of silver nitrate, a method which produces particles with average size of 12+/-2 nm, determined by Transmission Electron Microscopy (TEM). The plasmon absorbance is at 397 nm and the peak width at half maximum (PWHM) is 70-75 nm. The relationship between aggregation and optical properties was determined along with a method to protect the particles using polyvinylpyrrolidone (PVP). A laboratory experiment was designed in which students synthesize yellow colloidal silver, estimate particle size using visible spectroscopy, and study aggregation effects. The synthesis of the less stable copper nanoparticles is more difficult because copper nanopaticles are easily oxidized. Four methods were used for the synthesis of copper nanoparticles, including chemical reduction with sodium borohydride, sodium borohydride with potassium iodide, isopropyl alcohol with cetyltrimethylammonium bormide (CTAB) and reducing sugars. The latter method was also the basis for an undergraduate laboratory experiment. For each reaction, the dependence of stability of the copper nanoparticles on reagent concentrations, additives, relative amounts of reactants, and temperature is explored. Atomic force microscopy (AFM), TEM and UV-Visible Spectroscopy were used to characterize the copper nanoparticles. A laboratory experiment to produce copper nanoparticles from household chemicals was developed.

  4. Organocatalyzed asymmetric synthesis of morphans.

    PubMed

    Bradshaw, Ben; Parra, Claudio; Bonjoch, Josep

    2013-05-17

    A general effective organocatalyzed synthesis of enantioenriched morphans with up to 92% ee was developed. The morphan scaffold was constructed in a one-pot tandem asymmetric organocatalyzed Michael addition followed by a domino Robinson annulation/aza-Michael intramolecular reaction sequence from easily available starting materials.

  5. Phytochelatin synthesis in tomato cells

    SciTech Connect

    Goldsbrough, P.; Gupta, S.; Huang, B.; Scheller, H.

    1987-04-01

    Tomato cells that are exposed to cadmium and other heavy metals synthesize phytochelatins (PCs), a family of peptides that bind heavy metals and are structurally related to glutathione (GSH). PCs have the structure (..gamma..-glutamyl-cysteinyl) glycine; for PCs, n=2-10; GSH, n=1. GSH levels decline rapidly in tomato cells exposed to Cd/sup 2 +/. Buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, prevents sustained synthesis of PC. However the addition of GSH to the medium of BSO-treated cells restores PC production. In vivo labeling studies indicate that /sup 35/(S)-cysteine is incorporated into PC via GSH, rather than being added directly to GSH or pre-formed PC. Initial synthesis of PCs is not inhibited by cycloheximide. Tomato cell cultures that are tolerant of high levels of Cd/sup 2 +/ contain large amounts of PCs. However, when sensitive and tolerant cells that have been grown in the absence of Cd/sup 2 +/ are exposed to relatively low concentrations of Cd/sup 2 +/, they synthesize PCs at similar rates. These and other results suggest that, although PCs are necessary, increased PC synthesis is not sufficient for expression of the Cd/sup 2 +/ tolerant phenotype.

  6. Globin chain synthesis ratios in sideroblastic anaemia.

    PubMed

    Peters, R E; May, A; Jacobs, A

    1983-02-01

    Globin synthesis ratios were measured on reticulocytes from nine patients with primary acquired sideroblastic anaemia (SA), four patients with hereditary or congenital SA, two patients with secondary acquired SA and three patients with iron deficiency (ID). Ten of the samples from patients with SA and all the samples from patients with ID had normal ratios. Samples from three patients had significantly abnormal ratios, one from a patient with SA and acquired Hb H disease (alpha/beta 0 X 26), one from a patient with secondary acquired SA (alpha/beta 0 X 88), and one from a patient who went on to develop acute myeloblastic leukaemia (alpha/beta 1 X 36). Globin synthesis was stimulated by 100 microM haem similarly in normal, SA and ID reticulocytes. Any limitation of globin synthesis in SA and ID is therefore not easily reversible by adding haem. Inhibition of haem synthesis in nonsideroblastic reticulocytes using 4 mM isonicotinic acid hydrazide for 1 h incubation affected neither total globin synthesis nor the alpha/beta ratio. These results contradict the view that decreased haem synthesis decreases globin chain synthesis and decreases the alpha/beta globin chain synthesis ratios in human reticulocytes. Previously reported findings that haem could reverse globin chain synthesis inhibition in SA were good evidence for a primary deficiency of haem synthesis in the erythroblasts of these patients. Our inability to substantiate these findings emphasizes the need for a re-evaluation of the aetiology of sideroblastic anaemia.

  7. (1E,2E)-2-Methyl-3-phenyl­acryl­aldehyde thio­semicarbazone

    PubMed Central

    Mendoza-Meroño, Rafael; García-Granda, Santiago

    2012-01-01

    In the crystal structure of the title compound, C11H13N3S, mol­ecules form centrosymmetric synthons with an R 2 2(8) graph-set motif, linked by pairs of N—H⋯S hydrogen bonds. The synthons are connected through further N—H⋯S hydrogen bonds, extending the packing to form a two-dimensional network lying parallel to (001). In addition, C—H⋯π inter­actions are observed. PMID:22719608

  8. 4-Hy­droxy-3-meth­oxy­benzaldehyde 4-ethyl­thio­semicarbazone

    PubMed Central

    de Oliveira, Adriano Bof; Beck, Johannes; Daniels, Jörg; Feitosa, Bárbara Regina Santos

    2014-01-01

    In the crystal structure of the title compound, C11H15N3O2S, the C—N—N—C and C—N—C—C torsion angles involving the benzene ring and ethyl group are 11.91 (15) and 99.4 (2)°, respectively. An intra­molecular N—H⋯N hydrogen bond is observed. In the crystal, mol­ecules are linked via N—H⋯O and N—H⋯S hydrogen bonds into a three-dimensional hydrogen bonded network. Finally, the molecules show a herringbone arrangement when viewed along the a axis. PMID:25249915

  9. Crystal structure of 1-(4-formyl­benzyl­idene)-4-methyl­thio­semicarbazone

    PubMed Central

    Pino-Cuevas, Arantxa; Carballo, Rosa; Vázquez-López, Ezequiel M.

    2014-01-01

    The structure of the title compound, C10H11N3OS, comprises an approximately planar mol­ecule, with the r.m.s. deviation for the 15 non-H atoms being 0.089 Å. The conformation about the imine bond is E and an intra­molecular N—H⋯N hydrogen bond is evident. Mol­ecules are linked into a supra­molecular chain along the b axis by N—H⋯S hydrogen bonds. PMID:25309257

  10. Flow “Fine” Synthesis: High Yielding and Selective Organic Synthesis by Flow Methods

    PubMed Central

    2015-01-01

    Abstract The concept of flow “fine” synthesis, that is, high yielding and selective organic synthesis by flow methods, is described. Some examples of flow “fine” synthesis of natural products and APIs are discussed. Flow methods have several advantages over batch methods in terms of environmental compatibility, efficiency, and safety. However, synthesis by flow methods is more difficult than synthesis by batch methods. Indeed, it has been considered that synthesis by flow methods can be applicable for the production of simple gasses but that it is difficult to apply to the synthesis of complex molecules such as natural products and APIs. Therefore, organic synthesis of such complex molecules has been conducted by batch methods. On the other hand, syntheses and reactions that attain high yields and high selectivities by flow methods are increasingly reported. Flow methods are leading candidates for the next generation of manufacturing methods that can mitigate environmental concerns toward sustainable society. PMID:26337828

  11. Flow "Fine" Synthesis: High Yielding and Selective Organic Synthesis by Flow Methods.

    PubMed

    Kobayashi, Shū

    2016-02-18

    The concept of flow "fine" synthesis, that is, high yielding and selective organic synthesis by flow methods, is described. Some examples of flow "fine" synthesis of natural products and APIs are discussed. Flow methods have several advantages over batch methods in terms of environmental compatibility, efficiency, and safety. However, synthesis by flow methods is more difficult than synthesis by batch methods. Indeed, it has been considered that synthesis by flow methods can be applicable for the production of simple gasses but that it is difficult to apply to the synthesis of complex molecules such as natural products and APIs. Therefore, organic synthesis of such complex molecules has been conducted by batch methods. On the other hand, syntheses and reactions that attain high yields and high selectivities by flow methods are increasingly reported. Flow methods are leading candidates for the next generation of manufacturing methods that can mitigate environmental concerns toward sustainable society.

  12. Genetics Home Reference: congenital bile acid synthesis defect type 1

    MedlinePlus

    ... bile acid synthesis defect type 1 congenital bile acid synthesis defect type 1 Enable Javascript to view ... PDF Open All Close All Description Congenital bile acid synthesis defect type 1 is a disorder characterized ...

  13. Genetics Home Reference: congenital bile acid synthesis defect type 2

    MedlinePlus

    ... bile acid synthesis defect type 2 congenital bile acid synthesis defect type 2 Enable Javascript to view ... PDF Open All Close All Description Congenital bile acid synthesis defect type 2 is a disorder characterized ...

  14. The chemical synthesis of aryltetralin glycosides.

    PubMed

    Sun, Jian-Song; Liu, Hui; Guo, Xiao-Hong; Liao, Jin-Xi

    2016-01-28

    Led by etoposide and teniposide, the synthesis of aryltetralin glycosides has been experiencing flourishing development in the past five decades. Herein, a review focusing on the total synthesis of aryltetralin glycosides is provided. The main body of this review is composed of two parts, one is the enantioselective synthesis of aryltetralin derivatives and the other one is the construction of key glycosidic linkages. In each part the contents are organised based on the different strategies or protocols applied in the original documents. The total synthesis of aryltetralin glycosides represents the developing direction of this field, and sooner or later will replace the currently applied semi-total synthesis method, using the aglycon residue acquired directly from natural sources. This account provides a comprehensive and deep insight into the field of aryltetralin glycoside synthesis for chemists who have the intention of committing themselves to the development of aryltetralin glycoside medicine.

  15. Stereoselective Halogenation in Natural Product Synthesis.

    PubMed

    Chung, Won-jin; Vanderwal, Christopher D

    2016-03-24

    At last count, nearly 5000 halogenated natural products have been discovered. In approximately half of these compounds, the carbon atom to which the halogen is bound is sp(3) -hybridized; therefore, there are an enormous number of natural products for which stereocontrolled halogenation must be a critical component of any synthesis strategy. In this Review, we critically discuss the methods and strategies used for stereoselective introduction of halogen atoms in the context of natural product synthesis. Using the successes of the past, we also attempt to identify gaps in our synthesis technology that would aid the synthesis of halogenated natural products, as well as existing methods that have not yet seen application in complex molecule synthesis. The chemistry described herein demonstrates yet again how natural products continue to provide the inspiration for critical advances in chemical synthesis.

  16. Magnetically retrievable catalysts for organic synthesis.

    PubMed

    Baig, R B Nasir; Varma, Rajender S

    2013-01-28

    The use of magnetic nanoparticles (MNPs) as a catalyst support in organic synthesis is summarized. The recovery of expensive catalysts after catalytic reaction and reusing them without losing their activity is an essential feature in the sustainable process development. The aim of this article is to highlight the progress in the synthesis and catalytic applications of magnetic catalysts in organic synthesis. The heterogenization of the catalyst using magnetic nanoparticles allows it to be recovered and reused using an external magnet.

  17. Lipid synthesis during morphogenesis of Mucor racemosus.

    PubMed Central

    Ito, E T; Cihlar, R L; Inderlied, C B

    1982-01-01

    Lipid synthesis increases coordinately with protein and RNA synthesis during morphogenesis of Mucor racemosus. The lipid synthesis inhibitor cerulenin can completely block morphogenesis under conditions in which cell growth continues. An increase in phospholipid turnover may be an important correlate to morphogenesis of Mucor spp., especially the turnover of phosphotidyl inositol and phosphatidyl ethanolamine. The increase in ornithine decarboxylase, which occurs during morphogenesis, is inhibited by the addition of cerulenin. Images PMID:7130131

  18. Image Based Synthesis for Airborne Minefield Data

    DTIC Science & Technology

    2005-12-01

    applications of image synthesis include artificial texture generation [1], image repairing [2], photometric image rendering [3] and ultrasound imaging...1999. 4. M. Song, R. M. Haralick, F.H. Sheehan, " Ultrasound imaging simulation and echocardiographic image synthesis ", Proceedings of the IEEE...Night Vision and Electronic Sensors Directorate AMSRD-CER-NV-TR-246I Image Based Synthesis for Airborne Minefield Data December 2005 Approved for

  19. Polyurethane synthesis reactions in asphalts

    SciTech Connect

    Bukowski, A.; Gretkiewicz, J.

    1982-04-01

    A series of asphalt-polyurethane composites was prepared by means of polyurethane synthesis in asphalt and carried out in melt. The applied materials were asphalts of differentiated group components content, polyester polyols of chain structure from linear to strongly branched, 2,4-tolylene diisocyanate, 4,4-methylenebis(phenyl isocyanate), and tinorganic catalyst. The asphalt components react with isocyanates to a minimal degree. The influence of the applied substrates, temperature, and polyurethane content in the system on the basic kinetic relations characterizing the process is presented. Polyurethane synthesis in asphalts does not differ in a fundamental way from the obtaining of polyurethanes, especially when their content in the composition is significant, 20 wt% and more.

  20. Bioinspired iterative synthesis of polyketides

    PubMed Central

    Zheng, Kuan; Xie, Changmin; Hong, Ran

    2015-01-01

    Diverse array of biopolymers and second metabolites (particularly polyketide natural products) has been manufactured in nature through an enzymatic iterative assembly of simple building blocks. Inspired by this strategy, molecules with inherent modularity can be efficiently synthesized by repeated succession of similar reaction sequences. This privileged strategy has been widely adopted in synthetic supramolecular chemistry. Its value also has been reorganized in natural product synthesis. A brief overview of this approach is given with a particular emphasis on the total synthesis of polyol-embedded polyketides, a class of vastly diverse structures and biologically significant natural products. This viewpoint also illustrates the limits of known individual modules in terms of diastereoselectivity and enantioselectivity. More efficient and practical iterative strategies are anticipated to emerge in the future development. PMID:26052510

  1. Concise total synthesis of glucosepane.

    PubMed

    Draghici, Cristian; Wang, Tina; Spiegel, David A

    2015-10-16

    Glucosepane is a structurally complex protein posttranslational modification that is believed to exist in all living organisms. Research in humans suggests that glucosepane plays a critical role in the pathophysiology of both diabetes and human aging, yet comprehensive biological investigations of this metabolite have been hindered by a scarcity of chemically homogeneous material available for study. Here we report the total synthesis of glucosepane, enabled by the development of a one-pot method for preparation of the nonaromatic 4H-imidazole tautomer in the core. Our synthesis is concise (eight steps starting from commercial materials), convergent, high-yielding (12% overall), and enantioselective. We expect that these results will prove useful in the art and practice of heterocyclic chemistry and beneficial for the study of glucosepane and its role in human health and disease.

  2. Synthesis of Polycyclic Natural Products

    SciTech Connect

    Nguyen, Tuan Hoang

    2003-01-01

    With the continuous advancements in molecular biology and modern medicine, organic synthesis has become vital to the support and extension of those discoveries. The isolations of new natural products allow for the understanding of their biological activities and therapeutic value. Organic synthesis is employed to aid in the determination of the relationship between structure and function of these natural products. The development of synthetic methodologies in the course of total syntheses is imperative for the expansion of this highly interdisciplinary field of science. In addition to the practical applications of total syntheses, the structural complexity of natural products represents a worthwhile challenge in itself. The pursuit of concise and efficient syntheses of complex molecules is both gratifying and enjoyable.

  3. Cellulose Synthesis and Its Regulation

    PubMed Central

    Li, Shundai; Bashline, Logan; Lei, Lei; Gu, Ying

    2014-01-01

    Cellulose, the most abundant biopolymer synthesized on land, is made of linear chains of ß (1–4) linked D-glucose. As a major structural component of the cell wall, cellulose is important not only for industrial use but also for plant growth and development. Cellulose microfibrils are tethered by other cell wall polysaccharides such as hemicellulose, pectin, and lignin. In higher plants, cellulose is synthesized by plasma membrane-localized rosette cellulose synthase complexes. Despite the recent advances using a combination of molecular genetics, live cell imaging, and spectroscopic tools, many aspects of the cellulose synthesis remain a mystery. In this chapter, we highlight recent research progress towards understanding the mechanism of cellulose synthesis in Arabidopsis. PMID:24465174

  4. Detonation synthesis of superhard materials

    SciTech Connect

    Drobyshev, V.N.

    1983-09-01

    This article demonstrates how the high pressures and temperatures generated by solid explosive detonation can be directly utilized to synthesize superhard materials. The pressures and temperatures developed upon detonation, the size of the zone, and the chemical reaction time depend mainly on the power of the explosion and the density of the charge. The partial fusion of carbon or boron nitride with subsequent crystallization of diamond or the cubic boron nitride phase from the melt is considered. It is concluded that the detonation synthesis of superhard materials is distinguished by simplicity, quite high efficiency of conversion of original material into end product (up to 50%), the possibility of accomplishing synthesis in explosion chambers, and the possibility of superhard material production using automation techniques.

  5. Biphasic DNA Synthesis in Spumaviruses

    PubMed Central

    Delelis, Olivier; Saïb, Ali; Sonigo, Pierre

    2003-01-01

    Spumaviruses are complex retroviruses whose replication cycle resembles that of hepadnaviruses, especially by a late-occurring reverse transcription step. The possible existence of an early reverse transcription as observed in other retroviruses was not documented. Using real-time quantitative PCR, we addressed directly the kinetics of DNA synthesis during spumavirus infection. An early phase of viral DNA synthesis developed until 3 h postinfection, followed by a second phase, culminating 10 h postinfection. Both phases were abolished by the reverse transcriptase inhibitor 3′-azido-3′-deoxythymidine. Similar to other retroviruses, circular forms of viral DNA harboring two long terminal repeats were mainly found in the nucleus of infected cells. Interestingly, a fraction of these circular forms were detected in the cytoplasm and in extracellular virions, a feature shared with hepadnaviruses. Combined with packaging of both viral DNA and RNA genomes in virions, early and late reverse transcription might allow spumavirus to maximize its genome replication. PMID:12829852

  6. Hydrothermal synthesis of ammonium illite

    USGS Publications Warehouse

    Sucha, V.; Elsass, F.; Eberl, D.D.; Kuchta, L'.; Madejova, J.; Gates, W.P.; Komadel, P.

    1998-01-01

    Synthetic gel and glass of illitic composition, natural kaolinite, and mixed-layer illite-smectite were used as starting materials for hydrothermal synthesis of ammonium illite. Ammonium illite was prepared from synthetic gel by hydrothermal treatment at 300??C. The onset of crystallization began within 3 h, and well-crystallized ammonium illite appeared at 24 h. Increasing reaction time (up to four weeks) led to many illite layers per crystal. In the presence of equivalent proportions of potassium and ammonium, the gel was transformed to illite with equimolar contents of K and NH4. In contrast, synthesis using glass under the same conditions resulted in a mixture of mixed-layer ammonium illite-smectite with large expandability and discrete illite. Hydrothermal treatments of the fine fractions of natural kaolinite and illite-smectite produced ammonium illite from kaolinite but the illite-smectite remained unchanged.

  7. Synthesis of perfluoroalkylether triazine elastomers

    NASA Technical Reports Server (NTRS)

    Rosser, R. W.; Korus, R. A.

    1980-01-01

    A method of perfluoroalkylether triazine elastomer synthesis is described. To form an elastomer, the resultant polymer is heated in a closed oven at slightly reduced pressures for 1-day periods at 100, 130 and 150 C. A high-molecular-weight perfluoroalkylether triazine elastomer is produced that exhibits thermal and oxidative stability. This material is potentially useful in applications such as high-temperature seals, 'O' rings, and wire enamels.

  8. Total synthesis of (+/-)-chartelline C.

    PubMed

    Baran, Phil S; Shenvi, Ryan A

    2006-11-01

    The first total synthesis of (+/-)-chartelline C in a concise 10-step sequence is reported. Highlights of the completion of this decades-old puzzle include (1) chemo- and position-selective installation of the heteroaromatic halogens, (2) halogen-sparing monoreduction of an alkyne linker, (3) a simple strategy for placement of the sensitive beta-chloroenamide, (4) an unusually facile thermolysis of a vinyl carboxylic acid, and (5) a powerful ring contraction whose potential utility in heterocyclic chemistry merits further investigation.

  9. Total stereoselective synthesis of (+)-goniothalesdiol.

    PubMed

    Carreño, M Carmen; Hernández-Torres, Gloria; Urbano, Antonio; Colobert, Françoise

    2005-11-24

    [reaction: see text] The stereoselective synthesis of (+)-goniothalesdiol (1) was accomplished in nine steps starting from commercially available (-)-(2S,3S)-dimethyl D-tartrate (3). The key features were a completely diastereoselective reduction of a beta-ketosulfoxide to generate the stereogenic center at C-5 in 7 and formation of the 2,5-cis-substituted tetrahydrofuran ring in 10 from a stereoselective Et(3)SiH/TMSOTf-promoted reductive cyclization/deoxygenation.

  10. Synthesis of Thermally Stable Polymers

    DTIC Science & Technology

    1978-07-01

    LIST OF TABLES Table Page 1 Effect of Catalysts on the Polymerization of Diepoxides and Diisocyanates 11 2 Model Compound Studies 14 3 Polymerization of...Alkynyl-Substituted Polyurethanes 21 6 Effect of Temperature on the Hot Pressing of Polymer 67 24 x SECTION I INTRODUCTION The major objective of this...applying a high-temperature adhesive. Hence, a search for more effective catalysts was carried out. The third approach involved the synthesis of polymers

  11. Stereoselective Synthesis of Tilivalline(1).

    PubMed

    Nagasaka, Tatsuo; Koseki, Yuji

    1998-10-02

    Tilivalline 1, a metabolite from Klebsiella pneumoniae var. ocytoca, was easily synthesized in five steps from (S)-proline and 3-(benzyloxy)isatoic anhydride 4g. This synthesis is based on modified Curtius reactions of 3-substituted phthalic anhydrides 11 to 3-substituted isatoic anhydrides 4, conversion of lactams 6 to the acyliminium precursors 7 and stereoselective introduction of indole from the less hindered side of 7.

  12. Facile Enzymatic Synthesis of Ketoses**

    PubMed Central

    Wen, Liuqing; Huang, Kenneth; Wei, Mohui; Meisner, Jeffrey; Liu, Yunpeng; Garner, Kristina; Zang, Lanlan; Wang, Xuan; Li, Xu; Fang, Junqiang; Zhang, Houcheng

    2015-01-01

    Studies of rare ketoses have been hampered by a lack of efficient preparation methods. A convenient, efficient, and cost-effective platform for the facile synthesis of ketoses is described. This method enables the preparation of difficult-to-access ketopentoses and ketohexoses from common and inexpensive starting materials with high yield and purity and without the need for a tedious isomer separation step. PMID:26275233

  13. [Constitutive synthesis of cellulase by Trichoderma lignorum].

    PubMed

    Lobanok, A G; Pavlovskaia, Zh I

    1977-01-01

    The induction of cellulase synthesis by lactose was studied in the resting cells of Trichoderma lignorum OM 534. The effect depended on the concentration of lactose, pH, and the age of the mycelium. The induction of the enzyme synthesis by lactose is supressed by glucose and its metabolites. The repression by glucose is partly eliminated by Cyk 3'-5'-AMP, theophylline, and coffeine. The induction of cellulase by lactose is regarded as a derepression of the synthesis of this enzyme as a result of slow assimilation of the disaccharide. The synthesis of cellulase in T. lignorum is presumed to be constitutive.

  14. Modulation of protein synthesis by polyamines.

    PubMed

    Igarashi, Kazuei; Kashiwagi, Keiko

    2015-03-01

    Polyamines are ubiquitous small basic molecules that play important roles in cell growth and viability. Since polyamines mainly exist as a polyamine-RNA complex, we looked for proteins whose synthesis is preferentially stimulated by polyamines at the level of translation, and thus far identified 17 proteins in Escherichia coli and 6 proteins in eukaryotes. The mechanisms of polyamine stimulation of synthesis of these proteins were investigated. In addition, the role of eIF5A, containing hypusine formed from spermidine, on protein synthesis is described. These results clearly indicate that polyamines and eIF5A contribute to cell growth and viability through modulation of protein synthesis.

  15. Total Synthesis of Mycolactones A and B

    PubMed Central

    Song, Fengbin; Fidanze, Steve; Benowitz, Andrew B.; Kishi, Yoshito

    2007-01-01

    First and second generation total syntheses of mycolactones A and B are reported. The first generation total synthesis unambiguously confirmed our earlier assignment of the relative and absolute stereochemistry of mycolactones A and B. Knowledge of the chemical properties of the mycolactones accumulated through the first generation total synthesis allowed us to implement several major improvements to the original synthesis, including: (1) optimizing the choice of protecting groups, (2) eliminating the unnecessary adjustment of protecting groups, and (3) improving the overall stereoselectivity and synthetic efficiency. The second generation total synthesis consists of 21 longest linear steps, with 8.8% overall yield. PMID:17940589

  16. Quest for the chemical synthesis of proteins.

    PubMed

    Engelhard, Martin

    2016-05-01

    The chemical synthesis of proteins has been the wish of chemists since the early 19th century. There were decisive methodological steps necessary to accomplish this aim. Cornerstones were the introduction of the Z-protecting group of Bergmann and Zervas, the development of Solid-phase Peptide Synthesis of Merrifield, and the establishment of Native Chemical Ligation by Kent. Chemical synthesis of proteins has now become generally applicable technique for the synthesis of proteins with tailor made properties which can be applied not only in vitro but also in vivo .Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

  17. Enantioselective Synthesis of (−)-Acetylapoaranotin

    PubMed Central

    2017-01-01

    The first enantioselective total synthesis of the epipolythiodiketopiperazine (ETP) natural product (−)-acetylapoaranotin (3) is reported. The concise synthesis was enabled by an eight-step synthesis of a key cyclohexadienol-containing amino ester building block. The absolute stereochemistry of both amino ester building blocks used in the synthesis is set through catalytic asymmetric (1,3)-dipolar cycloaddition reactions. The formal syntheses of (−)-emethallicin E and (−)-haemotocin are also achieved through the preparation of a symmetric cyclohexadienol-containing diketopiperazine. PMID:28349698

  18. Tagetitoxin inhibits chloroplast RNA synthesis

    SciTech Connect

    Mathews, D.E.; Durbin, R.D.

    1987-04-01

    Tagetitoxin is a non-host specific phytotoxin which inhibits chloroplast development. Chloroplast encoded gene products as well as their transcripts are conspicuously depleted in toxin-treated tissue. Intact chloroplasts from 8-9 day old peas were incubated for 60 min. in the presence of tagetitoxin. This treatment reduced RNA synthesis but did not affect protein synthesis as measured by the incorporation of radiolabeled uridine or methionine, respectively. Tagetitoxin also inhibited chloroplast RNA synthesis in vitro. Total UTP incorporation was reduced 50% by 0.5..mu..M tagetitoxin in transcriptionally active chloroplast extracts containing 5mg/ml protein. In vitro transcription with purified E. coli RNA polymerase was also inhibited by tagetitoxin, yet wheat germ RNA polymerase II and several bacteriophage RNA polymerase enzymes were unaffected. Recent evidence suggests that RNA polymerase from chloroplasts and prokaryotes may share extensive homology. In light of this evidence and the authors own data, they propose that tagetitoxin directly inhibits chloroplast RNA polymerase.

  19. Total chemical synthesis of crambin.

    PubMed

    Bang, Duhee; Chopra, Neeraj; Kent, Stephen B H

    2004-02-11

    Crambin is a small (46 amino acids) protein isolated from the seeds of the plant Crambe abyssinica. Crambin has been extensively used as a model protein for the development of advanced crystallography and NMR techniques and for computational folding studies. We set out to establish synthetic access to crambin. Initially, we synthesized the 46 amino acid polypeptide by native chemical ligation of two distinct sets of peptide segments (15 + 31 and 31 + 15 residues). The synthetic polypeptide chain folded in good yield to give native crambin containing three disulfide bonds. The chemically synthesized crambin was characterized by LC-MS and by 2D-NMR. However, the 31-residue peptide segments were difficult to purify, and this caused an overall low yield for the synthesis. To overcome this problem, we synthesized crambin by the native chemical ligation of three segments (15 + 16 + 15 residues). Total synthesis using the ligation of three segments gave more than a 10-fold increase in yield and a protein product of exceptionally high purity. This work demonstrates the efficacy of chemical protein synthesis by the native chemical ligation of three segments and establishes efficient synthetic access to the important model protein crambin for experimental studies of protein folding and stability.

  20. Bile acids: regulation of synthesis.

    PubMed

    Chiang, John Y L

    2009-10-01

    Bile acids are physiological detergents that generate bile flow and facilitate intestinal absorption and transport of lipids, nutrients, and vitamins. Bile acids also are signaling molecules and inflammatory agents that rapidly activate nuclear receptors and cell signaling pathways that regulate lipid, glucose, and energy metabolism. The enterohepatic circulation of bile acids exerts important physiological functions not only in feedback inhibition of bile acid synthesis but also in control of whole-body lipid homeostasis. In the liver, bile acids activate a nuclear receptor, farnesoid X receptor (FXR), that induces an atypical nuclear receptor small heterodimer partner, which subsequently inhibits nuclear receptors, liver-related homolog-1, and hepatocyte nuclear factor 4alpha and results in inhibiting transcription of the critical regulatory gene in bile acid synthesis, cholesterol 7alpha-hydroxylase (CYP7A1). In the intestine, FXR induces an intestinal hormone, fibroblast growth factor 15 (FGF15; or FGF19 in human), which activates hepatic FGF receptor 4 (FGFR4) signaling to inhibit bile acid synthesis. However, the mechanism by which FXR/FGF19/FGFR4 signaling inhibits CYP7A1 remains unknown. Bile acids are able to induce FGF19 in human hepatocytes, and the FGF19 autocrine pathway may exist in the human livers. Bile acids and bile acid receptors are therapeutic targets for development of drugs for treatment of cholestatic liver diseases, fatty liver diseases, diabetes, obesity, and metabolic syndrome.

  1. Multiview synthesis for autostereoscopic displays

    NASA Astrophysics Data System (ADS)

    Dane, Gökçe.; Bhaskaran, Vasudev

    2013-09-01

    Autostereoscopic (AS) displays spatially multiplex multiple views, providing a more immersive experience by enabling users to view the content from different angles without the need of 3D glasses. Multiple views could be captured from multiple cameras at different orientations, however this could be expensive, time consuming and not applicable to some applications. The goal of multiview synthesis in this paper is to generate multiple views from a stereo image pair and disparity map by using various video processing techniques including depth/disparity map processing, initial view interpolation, inpainting and post-processing. We specifically emphasize the need for disparity processing when there is no depth information is available that is associated with the 2D data and we propose a segmentation based disparity processing algorithm to improve disparity map. Furthermore we extend the texture based 2D inpainting algorithm to 3D and further improve the hole-filling performance of view synthesis. The benefit of each step of the proposed algorithm is demonstrated with comparison to state of the art algorithms in terms of visual quality and PSNR metric. Our system is evaluated in an end-to-end multi view synthesis framework where only stereo image pair is provided as input to the system and 8 views are outputted and displayed in 8-view Alioscopy AS display.

  2. Chloroplast ribosomes and protein synthesis.

    PubMed Central

    Harris, E H; Boynton, J E; Gillham, N W

    1994-01-01

    Consistent with their postulated origin from endosymbiotic cyanobacteria, chloroplasts of plants and algae have ribosomes whose component RNAs and proteins are strikingly similar to those of eubacteria. Comparison of the secondary structures of 16S rRNAs of chloroplasts and bacteria has been particularly useful in identifying highly conserved regions likely to have essential functions. Comparative analysis of ribosomal protein sequences may likewise prove valuable in determining their roles in protein synthesis. This review is concerned primarily with the RNAs and proteins that constitute the chloroplast ribosome, the genes that encode these components, and their expression. It begins with an overview of chloroplast genome structure in land plants and algae and then presents a brief comparison of chloroplast and prokaryotic protein-synthesizing systems and a more detailed analysis of chloroplast rRNAs and ribosomal proteins. A description of the synthesis and assembly of chloroplast ribosomes follows. The review concludes with discussion of whether chloroplast protein synthesis is essential for cell survival. PMID:7854253

  3. New frontiers in design synthesis

    NASA Technical Reports Server (NTRS)

    Goldin, D. S.; Venneri, S. L.; Noor, A. K.

    1999-01-01

    The Intelligent Synthesis Environment (ISE), which is one of the major strategic technologies under development at NASA centers and the University of Virginia, is described. One of the major objectives of ISE is to significantly enhance the rapid creation of innovative affordable products and missions. ISE uses a synergistic combination of leading-edge technologies, including high performance computing, high capacity communications and networking, human-centered computing, knowledge-based engineering, computational intelligence, virtual product development, and product information management. The environment will link scientists, design teams, manufacturers, suppliers, and consultants who participate in the mission synthesis as well as in the creation and operation of the aerospace system. It will radically advance the process by which complex science missions are synthesized, and high-tech engineering Systems are designed, manufactured and operated. The five major components critical to ISE are human-centered computing, infrastructure for distributed collaboration, rapid synthesis and simulation tools, life cycle integration and validation, and cultural change in both the engineering and science creative process. The five components and their subelements are described. Related U.S. government programs are outlined and the future impact of ISE on engineering research and education is discussed.

  4. New frontiers in design synthesis.

    PubMed

    Goldin, D S; Venneri, S L; Noor, A K

    1999-01-01

    The Intelligent Synthesis Environment (ISE), which is one of the major strategic technologies under development at NASA centers and the University of Virginia, is described. One of the major objectives of ISE is to significantly enhance the rapid creation of innovative affordable products and missions. ISE uses a synergistic combination of leading-edge technologies, including high performance computing, high capacity communications and networking, human-centered computing, knowledge-based engineering, computational intelligence, virtual product development, and product information management. The environment will link scientists, design teams, manufacturers, suppliers, and consultants who participate in the mission synthesis as well as in the creation and operation of the aerospace system. It will radically advance the process by which complex science missions are synthesized, and high-tech engineering Systems are designed, manufactured and operated. The five major components critical to ISE are human-centered computing, infrastructure for distributed collaboration, rapid synthesis and simulation tools, life cycle integration and validation, and cultural change in both the engineering and science creative process. The five components and their subelements are described. Related U.S. government programs are outlined and the future impact of ISE on engineering research and education is discussed.

  5. Microwave assisted synthesis, characterization and biological evaluation of palladium and platinum complexes with azomethines

    NASA Astrophysics Data System (ADS)

    Sharma, Krishna; Singh, Ritu; Fahmi, Nighat; Singh, R. V.

    2010-01-01

    Reactions of 3-acetyl-2,5-dimethylthiophene with thiosemicarbazide and semicarbazide hydrochloride resulted in the formation of new heterocyclic ketimines, 3-acetyl-2,5-dimethylthiophene thiosemicarbazone (C 9H 13N 3OS 2 or L 1H) and 3-acetyl-2,5- dimethylthiophene semicarbazone (C 9H 13N 3OS or L 2H), respectively. The Pd(II) and Pt(II) complexes have been synthesized by mixing metal salts in 1:2 molar ratios with these ligands by using microwave as well as conventional heating method for comparison purposes. The authenticity of these ligands and their complexes has been established on the basis of elemental analysis, melting point determinations, molecular weight determinations, IR, 1H NMR and UV spectral studies. These studies showed that the ligands coordinate to the metal atom in a monobasic bidentate manner and square planar environment around the metal atoms has been proposed to the complexes. Both the ligands and their complexes have been screened for their antimicrobial activities. The antiamoebic activity of both the ligands and their palladium compounds against the protozoan parasite Entamoeba histolytica has been tested.

  6. Synthesis and density functional theoretical study of steroidal spiro-triazolidinone.

    PubMed

    Sharma, Kamlesh; Lal, Bhajan

    2008-06-01

    The reaction of 3beta-chloro-5alpha-cholestan-6-one semicarbazone 1 with hydrogen peroxide at 0 degrees C gives 3beta-chloro-5alpha-cholestan-6-spiro-1',2',4'-triazolidine-3'-one 2 as a product. The structural assignment of the product was confirmed on the basis of its elemental, analytical and spectral data. The ab initio calculations were performed by using density functional theory (DFT) at B3LYP/6-31G* basis set in order to describe a free radical reaction mechanism. The reaction proceeds through two radical intermediates formation. The mechanism of the reaction was explained by using frontier molecular orbital (FMO), spin electronic density map, encoded electrostatic potential map and atomic charges. It was found that the localization of frontier orbitals and the flow of atomic charges of all the calculated structures support the present reaction mechanism. The molecular properties like total energy, dipole moment and hardness of each optimized structure, were also explained. Stability of all the optimized structures in this study was supported by their respective fundamental frequencies and energy minima.

  7. Starch synthesis in Arabidopsis. Granule synthesis, composition, and structure.

    PubMed

    Zeeman, Samuel C; Tiessen, Axel; Pilling, Emma; Kato, K Lisa; Donald, Athene M; Smith, Alison M

    2002-06-01

    The aim of this work was to characterize starch synthesis, composition, and granule structure in Arabidopsis leaves. First, the potential role of starch-degrading enzymes during starch accumulation was investigated. To discover whether simultaneous synthesis and degradation of starch occurred during net accumulation, starch was labeled by supplying (14)CO(2) to intact, photosynthesizing plants. Release of this label from starch was monitored during a chase period in air, using different light intensities to vary the net rate of starch synthesis. No release of label was detected unless there was net degradation of starch during the chase. Similar experiments were performed on a mutant line (dbe1) that accumulates the soluble polysaccharide, phytoglycogen. Label was not released from phytoglycogen during the chase indicating that, even when in a soluble form, glucan is not appreciably degraded during accumulation. Second, the effect on starch composition of growth conditions and mutations causing starch accumulation was studied. An increase in starch content correlated with an increased amylose content of the starch and with an increase in the ratio of granule-bound starch synthase to soluble starch synthase activity. Third, the structural organization and morphology of Arabidopsis starch granules was studied. The starch granules were birefringent, indicating a radial organization of the polymers, and x-ray scatter analyses revealed that granules contained alternating crystalline and amorphous lamellae with a periodicity of 9 nm. Granules from the wild type and the high-starch mutant sex1 were flattened and discoid, whereas those of the high-starch mutant sex4 were larger and more rounded. These larger granules contained "growth rings" with a periodicity of 200 to 300 nm. We conclude that leaf starch is synthesized without appreciable turnover and comprises similar polymers and contains similar levels of molecular organization to storage starches, making Arabidopsis

  8. Novel synthesis of substituted benzylidenecyclohexanone by microwave assisted organic synthesis

    NASA Astrophysics Data System (ADS)

    Handayani, Sri; Budimarwanti, Cornelia; Haryadi, Winarto

    2017-03-01

    Benzylidenecyclohexanone derivatives are compounds with wide bioactivity. Usually, it was synthesized from cyclohexanones and benzaldehyde derivatives under base condition. This research presents a rapid and simple method to synthesis substituted benzylidenecyclohexanone. Cyclohexanone was mixed with 4-hydroxybenzaldehyde in acid condition under MAOS for 2 minutes, then it was left to cooled. Brownish purple powder in 81.47% yield was obtained. The product was identified by gas chromatography, then followed by structure elucidation by using NMR spectrophotometer. The novel compound is confirmed as 4-((E)-((1E,3'E)-3'-(4-hydroxybenzylidene)-2'-oxo-[1,1'-bi(cyclohexylidene)]-2,5-dienylidene-4-ylidene) me-thoxy)benzaldehyde.

  9. Synthesis Of B, B', B"-Trichloroborazine

    NASA Technical Reports Server (NTRS)

    Riccitiello, Salvatore R.; Chen, Timothy S.; Hsu, Ming-Ta S.

    1988-01-01

    Simplified, relatively safe, and economical synthesis of B, B', B"-trichloroborazine easily practiced in standard organic-chemistry laboratory. Yield is 20 to 30 percent, fairly acceptable value in view of inherent difficulty of synthesizing borazines. New synthesis has potential use in industry.

  10. Synthesis and Photocatalytic Reactivity of Vinylsulfonium Ylides.

    PubMed

    Klose, Immo; Misale, Antonio; Maulide, Nuno

    2016-08-19

    Although sulfur ylides are textbook reagents in organic synthesis, surprisingly little variation of substituents on sulfur is usually observed. In particular, vinylsulfonium ylides have been neglected so far. Herein, we present a study on their synthesis and reactivity, including interesting behavior under photocatalytic conditions.

  11. Sustainable Synthesis of Nanomaterials Using Microwave irradiation

    EPA Science Inventory

    The presentation summarizes our recent activity in MW-assisted synthesis of nanomaterials under benign conditions. Shape-controlled aqueous synthesis of noble nanostructures via MW-assisted spontaneous reduction of noble metal salts using -D-glucose, sucrose, and maltose will be...

  12. A Concise Asymmetric Total Synthesis of (+)-Brevisamide

    PubMed Central

    Herrmann, Aaron T.; Martinez, Steven R.; Zakarian, Armen

    2012-01-01

    A new protecting-group-free synthesis of the marine monocyclic ether (+)-brevisamide is reported. The enantioselective synthesis utilizes a key asymmetric Henry reaction and an Achmatowicz rearrangement for the formation of the tetrahydropyran ring. A penultimate Stille cross-coupling allows for an efficient installation of the conjugated (E,E)-diene side chain ultimately delivering (+)-brevisamide. PMID:21678904

  13. Flexible synthesis of polyfunctionalised 3-fluoropyrroles.

    PubMed

    Cogswell, Thomas J; Donald, Craig S; Marquez, Rodolfo

    2016-01-07

    An efficient and selective approach for the synthesis of polyfunctionalised 3-fluoropyrroles has been developed starting from commercial aldehydes. The methodology is concise, efficient and allows for the modular and systematic assembly of polysubstituted 3-fluoropyrroles. This synthesis provides an alternative and highly convergent strategy for the generation of these chemically and biologically important units.

  14. Web-Mediated Knowledge Synthesis for Educators

    ERIC Educational Resources Information Center

    DeSchryver, Michael

    2015-01-01

    Ubiquitous and instant access to information on the Web is challenging what constitutes 21st century literacies. This article explores the notion of Web-mediated knowledge synthesis, an approach to integrating Web-based learning that may result in generative synthesis of ideas. This article describes the skills and strategies that may support…

  15. Synthesis Sheets: An Aid To Synthetic Analysis

    ERIC Educational Resources Information Center

    Still, W. Clark

    1973-01-01

    Describes the development of a scheme which allows the production of a complete synthesis tree through the backward analysis of a target molecule into precursor and pathway catalogues. The logical organizing framework will find applications to teaching of multistep organic synthesis. (CC)

  16. Synthesizing Evidence: Synthesis Methods for Evidence Clearinghouses

    ERIC Educational Resources Information Center

    Valentine, Jeff; Lau, Timothy

    2015-01-01

    Following the theme of the first two presentations, this presentation will focus on the choices available for research synthesis when summarizing research evidence. The presenters will describe the current research synthesis practice of the What Works Clearinghouse (WWC) as well as several alternative models, including inverse-variance weighted…

  17. SCMC for SLA: A Research Synthesis

    ERIC Educational Resources Information Center

    Sauro, Shannon

    2011-01-01

    This research synthesis explores the role of synchronous computer-mediated communication (SCMC) for second language acquisition (SLA). Using Hymes' (1971) notion of communicative competence and Canale and Swain's (1980; Canale, 1983) subsequent framework for communicative language teaching, the synthesis examines the research trends, methods, and…

  18. Lactobacillus assisted synthesis of titanium nanoparticles

    NASA Astrophysics Data System (ADS)

    Prasad, K.; Jha, Anal K.; Kulkarni, A. R.

    2007-05-01

    An eco-friendly lactobacillus sp. (microbe) assisted synthesis of titanium nanoparticles is reported. The synthesis is performed at room temperature. X-ray and transmission electron microscopy analyses are performed to ascertain the formation of Ti nanoparticles. Individual nanoparticles as well as a number of aggregates almost spherical in shape having a size of 40 60 nm are found.

  19. Combustion synthesis of advanced composite materials

    NASA Technical Reports Server (NTRS)

    Moore, John J.

    1993-01-01

    Self-propagating high temperature (combustion) synthesis (SHS), has been investigated as a means of producing both dense and expanded (foamed) ceramic and ceramic-metal composites, ceramic powders and whiskers. Several model exothermic combustion synthesis reactions were used to establish the importance of certain reaction parameters, e.g., stoichiometry, green density, combustion mode, particle size, etc. on the control of the synthesis reaction, product morphology and properties. The use of an in situ liquid infiltration technique and the effect of varying the reactants and their stoichiometry to provide a range of reactant and product species i.e., solids, liquids and gases, with varying physical properties e.g., volatility and thermal conductivity, on the microstructure and morphology of synthesized composite materials is discussed. Conducting the combustion synthesis reaction in a reactive gas environment to take advantage of the synergistic effects of combustion synthesis and vapor phase transport is also examined.

  20. Protein chemical synthesis in drug discovery.

    PubMed

    Liu, Fa; Mayer, John P

    2015-01-01

    The discovery of novel therapeutics to combat human disease has traditionally been among the most important goals of research chemists. After a century of innovation, state-of-the-art chemical protein synthesis is now capable of efficiently assembling proteins of up to several hundred residues in length from individual amino acids. By virtue of its unique ability to incorporate non-native structural elements, chemical protein synthesis has been seminal in the recent development of several novel drug discovery technologies. In this chapter, we review the key advances in peptide and protein chemistry which have enabled our current synthetic capabilities. We also discuss the synthesis of D-proteins and their applications in mirror image phage-display and racemic protein crystallography, the synthesis of enzymes for structure-based drug discovery, and the direct synthesis of homogenous protein pharmaceuticals.

  1. Texture synthesis and transfer from multiple samples

    NASA Astrophysics Data System (ADS)

    Qi, Yue; Zhao, Qinping

    2003-09-01

    Texture Mapping plays a very important role in Computer Graphics. Texture Synthesis is one of the main methods to obtain textures, it makes use of sample textures to generate new textures. Texture Transfer is based on Texture Synthesis, it renders objects with textures taken from different objects. Currently, most of Texture Synthesis and Transfer methods use a single sample texture. A method for Texture Synthesis adn Transfer from multi samples was presented. For texture synthesis, the L-shaped neighborhood seaching approach was used. Users specify the proportion of each sample, the number of seed points, and these seed points are scattered randomly according to their samples in horizontal and vertical direction synchronously to synthesize textures. The synthesized textures are very good. For texture transfer, the luminance of the target image and the sample textures are analyzed. This procedure is from coarse to fine, and can produce a visually pleasing result.

  2. Astrobiology - The New Synthesis

    NASA Astrophysics Data System (ADS)

    Sik, A.; Simon, T.

    á vált sötétebb helyekre való költöztetése: mélyen a föld alá helyezik, a forró vulkáni kőzetek hasadékaiba, ahol bőségesen találhatott magának ként, vasat, hidrogént és szenet. A genetikai bizonyítékok alapján a hő- és mélységkedvelők es- 4 nek legközelebb az egyetemes őshöz. [16]. The synthesis Mindezek alapján a földi extremofilek vizsgálata során deríthetjük ki, hogy más égitesteken (egyelőre a Naprendszerben) hol kell keresnünk az életet, és mit kell keresnünk a planetológiai kutatások során egyre jobban megismert szélsőséges környezetekben. Segítségükkel megtudhatjuk, melyek azok az alak- tani, geokémiai, esetleg biokémiai jegyek, amelyek életre utalhatnak; melyek az élet azon alapvető jellemzői, amelyek elég általánosak és biztonsággal kimu- tathatók, milyen műszerekkel kell felszerelnünk a jövő űrszondáit, milyen módszereket kell alkalmaznunk, hogy sikerrel kutathassunk a Földön kívüli élet után. References [1] H. Hargitai et. al., XXXIII. LPSC (2002), Houston, #1261; [2] Origins Roadmap, 2000, JPL; [3] http://www.obspm.fr/encycl/catalog.html [4] http://www.physics.sfsu.edu/~gmarcy/planetsearch/ upsand/upsand.html [5] http://tpf.jpl.nasa.gov/ [6] A. Kereszturi, and A. Sik, XXXI. LPSC (2000), Houston, #1216; [7] S. W. Squyres et. al. (1992) in H. H. Kieffer, et. al.: Mars, University of Arizona Press, Tucson, 523-554; [8] http://www.jpl.nasa.gov/europaorbiter/ [9] www.nineplanets.org [10] http://www.jpl.nasa.gov/cassini/ [11] http://www- curator.jsc.nasa.gov/curator/antmet/ marsmets/alh84001/sample.htm [12] P. Davies: The fifth miracle - The search for the origin of life (1998), Orion; [13] M. T. Madigan and B. L. Marrs: Extremophiles, Scientific American (1997), 276, 82-87; [14] J. A. Lake et al.: Methanococcus Genome, Science (1996), 274, 901-905; [15] N. C. Kyrpides and G. J. Olsen: Archaeal and bacterial hyperthermophiles: Horizontal gene exchange or common ancestry?, Trends in

  3. The Synthesis Paradigm in Genetics

    PubMed Central

    Rice, William R.

    2014-01-01

    Experimental genetics with model organisms and mathematically explicit genetic theory are generally considered to be the major paradigms by which progress in genetics is achieved. Here I argue that this view is incomplete and that pivotal advances in genetics—and other fields of biology—are also made by synthesizing disparate threads of extant information rather than generating new information from experiments or formal theory. Because of the explosive expansion of information in numerous “-omics” data banks, and the fragmentation of genetics into numerous subdisciplines, the importance of the synthesis paradigm will likely expand with time. PMID:24496401

  4. Computer Music Synthesis and Composition

    NASA Astrophysics Data System (ADS)

    Ayers, Lydia

    What is computer music composition? Composers are using the computer for everything from MIDI instruments communicating with computer sequencers, pitch trackers analyzing the sounds of acoustic instruments and converting them to pitch information, live performers with recorded music, performers with interactive computer programs, computer music produced by dancers using sensors, automatic music composition with the computer programs composing the music, composing with sounds or parts of sounds rather than notes, how to structure the use of time, composing with timbres, or the colors of sounds, and timbre morphing, such as a gong morphing to a voice, composing with textures and texture morphing, such as fluttertonguing morphing to pitch, granular synthesis, trills and convolution.

  5. Cellulose Synthesis in Agrobacterium tumefaciens

    SciTech Connect

    Alan R. White; Ann G. Matthysse

    2004-07-31

    We have cloned the celC gene and its homologue from E. coli, yhjM, in an expression vector and expressed the both genes in E. coli; we have determined that the YhjM protein is able to complement in vitro cellulose synthesis by extracts of A. tumefaciens celC mutants, we have purified the YhjM protein product and are currently examining its enzymatic activity; we have examined whole cell extracts of CelC and various other cellulose mutants and wild type bacteria for the presence of cellulose oligomers and cellulose; we have examined the ability of extracts of wild type and cellulose mutants including CelC to incorporate UDP-14C-glucose into cellulose and into water-soluble, ethanol-insoluble oligosaccharides; we have made mutants which synthesize greater amounts of cellulose than the wild type; and we have examined the role of cellulose in the formation of biofilms by A. tumefaciens. In addition we have examined the ability of a putative cellulose synthase gene from the tunicate Ciona savignyi to complement an A. tumefaciens celA mutant. The greatest difference between our knowledge of bacterial cellulose synthesis when we started this project and current knowledge is that in 1999 when we wrote the original grant very few bacteria were known to synthesize cellulose and genes involved in this synthesis were sequenced only from Acetobacter species, A. tumefaciens and Rhizobium leguminosarum. Currently many bacteria are known to synthesize cellulose and genes that may be involved have been sequenced from more than 10 species of bacteria. This additional information has raised the possibility of attempting to use genes from one bacterium to complement mutants in another bacterium. This will enable us to examine the question of which genes are responsible for the three dimensional structure of cellulose (since this differs among bacterial species) and also to examine the interactions between the various proteins required for cellulose synthesis. We have carried out one

  6. Machine-Assisted Organic Synthesis.

    PubMed

    Ley, Steven V; Fitzpatrick, Daniel E; Myers, Rebecca M; Battilocchio, Claudio; Ingham, Richard J

    2015-08-24

    In this Review we describe how the advent of machines is impacting on organic synthesis programs, with particular emphasis on the practical issues associated with the design of chemical reactors. In the rapidly changing, multivariant environment of the research laboratory, equipment needs to be modular to accommodate high and low temperatures and pressures, enzymes, multiphase systems, slurries, gases, and organometallic compounds. Additional technologies have been developed to facilitate more specialized reaction techniques such as electrochemical and photochemical methods. All of these areas create both opportunities and challenges during adoption as enabling technologies.

  7. Synthesis of Lysine Methyltransferase Inhibitors

    NASA Astrophysics Data System (ADS)

    Ye, Tao; Hui, Chunngai

    2015-07-01

    Lysine methyltransferase which catalyze methylation of histone and nonhistone proteins, play a crucial role in diverse biological processes and has emerged as a promising target for the development of various human diseases, including cancer, inflammation, and psychiatric disorders. However, inhibiting Lysine methyltransferases selectively has presented many challenges to medicinal chemists. During the past decade, lysine methyltransferase inhibitors covering many different structural classes have been designed and developed. In this review, we describe the development of selective, small-molecule inhibitors of lysine methyltransferases with an emphasis on their discovery and chemical synthesis. We highlight the current state of lysine methyltransferase inhibitors and discuss future directions and opportunities for lysine methyltransferase inhibitor discovery.

  8. fsclean: Faraday Synthesis CLEAN imager

    NASA Astrophysics Data System (ADS)

    Bell, M. R.; Ensslin, T. A.

    2015-06-01

    Fsclean produces 3D Faraday spectra using the Faraday synthesis method, transforming directly from multi-frequency visibility data to the Faraday depth-sky plane space. Deconvolution is accomplished using the CLEAN algorithm, and the package includes Clark and Högbom style CLEAN algorithms. Fsclean reads in MeasurementSet visibility data and produces HDF5 formatted images; it handles images and data of arbitrary size, using scratch HDF5 files as buffers for data that is not being immediately processed, and is limited only by available disk space.

  9. Pilot-optimal augmentation synthesis

    NASA Technical Reports Server (NTRS)

    Schmidt, D. K.

    1978-01-01

    An augmentation synthesis method usable in the absence of quantitative handling qualities specifications, and yet explicitly including design objectives based on pilot-rating concepts, is presented. The algorithm involves the unique approach of simultaneously solving for the stability augmentation system (SAS) gains, pilot equalization and pilot rating prediction via optimal control techniques. Simultaneous solution is required in this case since the pilot model (gains, etc.) depends upon the augmented plant dynamics, and the augmentation is obviously not a priori known. Another special feature is the use of the pilot's objective function (from which the pilot model evolves) to design the SAS.

  10. Synthesis of new nanocrystal materials

    NASA Astrophysics Data System (ADS)

    Hassan, Yasser Hassan Abd El-Fattah

    Colloidal semiconductor nanocrystals (NCs) have sparked great excitement in the scientific community in last two decades. NCs are useful for both fundamental research and technical applications in various fields owing to their size and shape-dependent properties and their potentially inexpensive and excellent chemical processability. These NCs are versatile fluorescence probes with unique optical properties, including tunable luminescence, high extinction coefficient, broad absorption with narrow photoluminescence, and photobleaching resistance. In the past few years, a lot of attention has been given to nanotechnology based on using these materials as building blocks to design light harvesting assemblies. For instant, the pioneering applications of NCs are light-emitting diodes, lasers, and photovoltaic devices. Synthesis of the colloidal stable semiconductor NCs using the wet method of the pyrolysis of organometallic and chalcogenide precursors, known as hot-injection approach, is the chart-topping preparation method in term of high quality and monodisperse sized NCs. The advancement in the synthesis of these artificial materials is the core step toward their applications in a broad range of technologies. This dissertation focuses on exploring various innovative and novel synthetic methods of different types of colloidal nanocrystals, both inorganic semiconductors NCs, also known as quantum dots (QDs), and organic-inorganic metal halide-perovskite materials, known as perovskites. The work presented in this thesis focuses on pursuing fundamental understanding of the synthesis, material properties, photophysics, and spectroscopy of these nanostructured semiconductor materials. This thesis contains 6 chapters and conclusions. Chapters 1?3 focus on introducing theories and background of the materials being synthesized in the thesis. Chapter 4 demonstrates our synthesis of colloidal linker--free TiO2/CdSe NRs heterostructures with CdSe QDs grown in the presence of Ti

  11. Mechanochemistry: A Force of Synthesis

    PubMed Central

    2016-01-01

    The past decade has seen a reawakening of solid-state approaches to chemical synthesis, driven by the search for new, cleaner synthetic methodologies. Mechanochemistry, i.e., chemical transformations initiated or sustained by mechanical force, has been advancing particularly rapidly, from a laboratory curiosity to a widely applicable technique that not only enables a cleaner route to chemical transformations but offers completely new opportunities in making and screening for molecules and materials. This Outlook provides a brief overview of the recent achievements and opportunities created by mechanochemistry, including access to materials, molecular targets, and synthetic strategies that are hard or even impossible to access by conventional means. PMID:28149948

  12. Machine‐Assisted Organic Synthesis

    PubMed Central

    Fitzpatrick, Daniel E.; Myers, Rebecca M.; Battilocchio, Claudio; Ingham, Richard. J.

    2015-01-01

    Abstract In this Review we describe how the advent of machines is impacting on organic synthesis programs, with particular emphasis on the practical issues associated with the design of chemical reactors. In the rapidly changing, multivariant environment of the research laboratory, equipment needs to be modular to accommodate high and low temperatures and pressures, enzymes, multiphase systems, slurries, gases, and organometallic compounds. Additional technologies have been developed to facilitate more specialized reaction techniques such as electrochemical and photochemical methods. All of these areas create both opportunities and challenges during adoption as enabling technologies. PMID:26193360

  13. Research on Intelligent Synthesis Environments

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Lobeck, William E.

    2002-01-01

    Four research activities related to Intelligent Synthesis Environment (ISE) have been performed under this grant. The four activities are: 1) non-deterministic approaches that incorporate technologies such as intelligent software agents, visual simulations and other ISE technologies; 2) virtual labs that leverage modeling, simulation and information technologies to create an immersive, highly interactive virtual environment tailored to the needs of researchers and learners; 3) advanced learning modules that incorporate advanced instructional, user interface and intelligent agent technologies; and 4) assessment and continuous improvement of engineering team effectiveness in distributed collaborative environments.

  14. The synthesis paradigm in genetics.

    PubMed

    Rice, William R

    2014-02-01

    Experimental genetics with model organisms and mathematically explicit genetic theory are generally considered to be the major paradigms by which progress in genetics is achieved. Here I argue that this view is incomplete and that pivotal advances in genetics--and other fields of biology--are also made by synthesizing disparate threads of extant information rather than generating new information from experiments or formal theory. Because of the explosive expansion of information in numerous "-omics" data banks, and the fragmentation of genetics into numerous subdisciplines, the importance of the synthesis paradigm will likely expand with time.

  15. Concise Synthesis of Functionalized Benzocyclobutenones

    PubMed Central

    Chen, Peng-hao; Savage, Nikolas A.; Dong, Guangbin

    2014-01-01

    A concise approach to access functionalized benzocyclobutenones from 3-halophenol derivatives is described. This modified synthesis employs a [2+2] cycloaddition between benzynes generated from dehydrohalogenation of aryl halides using LiTMP and acetaldehyde enolate generated from n-BuLi and THF, followed by oxidation of the benzocyclobutenol intermediates to provide benzocyclobutenones. The [2+2] reaction can be run on a 10-gram scale with an increased yield. A number of functional groups including alkenes and alkynes are tolerated. Coupling of benzynes with ketene silyl acetals to give 8-substituted benzocyclobutenones is also demonstrated. PMID:24926108

  16. Indenylmetal Catalysis in Organic Synthesis.

    PubMed

    Trost, Barry M; Ryan, Michael C

    2017-03-06

    Synthetic organic chemists have a long-standing appreciation for transition metal cyclopentadienyl complexes, of which many have been used as catalysts for organic transformations. Much less well known are the contributions of the benzo-fused relative of the cyclopentadienyl ligand, the indenyl ligand, whose unique properties have in many cases imparted differential reactivity in catalytic processes toward the synthesis of small molecules. In this Review, we present examples of indenylmetal complexes in catalysis and compare their reactivity to their cyclopentadienyl analogues, wherever possible.

  17. Synthesis of tunable tellurium nanoparticles

    NASA Astrophysics Data System (ADS)

    Guisbiers, G.; Mimun, L. C.; Mendoza-Cruz, R.; Nash, K. L.

    2017-04-01

    Tellurium is a chalcogenide element, essential, in the development of renewable energy solutions. However, substantial problems remain to synthesize zero-dimensional tellurium nanostructures in a facile and environmentally friendly way. This communication reports the first successful synthesis of pure tellurium nanoparticles by laser ablation in liquids. Two solvents were used i.e. de-ionized water and acetone. The effect of wavelength on the size and crystallinity of the produced nanoparticles has been investigated. The thermal stability and the size-dependent energy bandgap has also been predicted using nano-thermodynamics. Finally, the most stable colloidal solution as well as the smallest size distribution was obtained in acetone.

  18. The Synthesis and Purification of Aromatic Hydrocarbons. 1 - Butylbenzene

    DTIC Science & Technology

    1946-01-01

    Synthesis (19440); Chemistry, Organic - Synthesis (23238); Hydrogenation firm, ^’bJ&JL fUdtOls DIVISION: Sciences, General W3J/3. SECTION: Chemistry...Chemistry (1) ATI SHEET NO.: R-33-1-7 SUBJECT HEADINGS: Butylbenzene - Synthesis (19440); Chemistry, Organic - Synthesis (23238); Hydrogenation (49915

  19. Synthesis, Characterization and Application of Functional Carbon Nano Materials

    DTIC Science & Technology

    2014-05-05

    NO. 0704-0188 3. DATES COVERED (From - To) - UU UU UU UU 22-07-2014 Approved for public release; distribution is unlimited. SYNTHESIS ...CHARACTERIZATION AND APPLICATION OFFUNCTIONAL CARBON NANO MATERIALS The synthesis , characterizations and applications of carbon nanomaterials, including carbon...PR 00931 -1790 ABSTRACT SYNTHESIS , CHARACTERIZATION AND APPLICATION OFFUNCTIONAL CARBON NANO MATERIALS Report Title The synthesis , characterizations

  20. Mixed Alcohol Synthesis Catalyst Screening

    SciTech Connect

    Gerber, Mark A.; White, James F.; Stevens, Don J.

    2007-09-03

    National Renewable Energy Laboratory (NREL) and Pacific Northwest National Laboratory (PNNL) are conducting research to investigate the feasibility of producing mixed alcohols from biomass-derived synthesis gas (syngas). PNNL is tasked with obtaining commercially available or preparing promising mixed-alcohol catalysts and screening them in a laboratory-scale reactor system. Commercially available catalysts and the most promising experimental catalysts are provided to NREL for testing using a slipstream from a pilot-scale biomass gasifier. From the standpoint of producing C2+ alcohols as the major product, it appears that the rhodium catalyst is the best choice in terms of both selectivity and space-time yield (STY). However, unless the rhodium catalyst can be improved to provide minimally acceptable STYs for commercial operation, mixed alcohol synthesis will involve significant production of other liquid coproducts. The modified Fischer-Tropsch catalyst shows the most promise for providing both an acceptable selectivity to C2+ alcohols and total liquid STY. However, further optimization of the Fischer-Tropsch catalysts to improve selectivity to higher alcohols is highly desired. Selection of a preferred catalyst will likely entail a decision on the preferred coproduct slate. No other catalysts tested appear amenable to the significant improvements needed for acceptable STYs.

  1. Fluxnet Synthesis Dataset Collaboration Infrastructure

    SciTech Connect

    Agarwal, Deborah A.; Humphrey, Marty; van Ingen, Catharine; Beekwilder, Norm; Goode, Monte; Jackson, Keith; Rodriguez, Matt; Weber, Robin

    2008-02-06

    The Fluxnet synthesis dataset originally compiled for the La Thuile workshop contained approximately 600 site years. Since the workshop, several additional site years have been added and the dataset now contains over 920 site years from over 240 sites. A data refresh update is expected to increase those numbers in the next few months. The ancillary data describing the sites continues to evolve as well. There are on the order of 120 site contacts and 60proposals have been approved to use thedata. These proposals involve around 120 researchers. The size and complexity of the dataset and collaboration has led to a new approach to providing access to the data and collaboration support and the support team attended the workshop and worked closely with the attendees and the Fluxnet project office to define the requirements for the support infrastructure. As a result of this effort, a new website (http://www.fluxdata.org) has been created to provide access to the Fluxnet synthesis dataset. This new web site is based on a scientific data server which enables browsing of the data on-line, data download, and version tracking. We leverage database and data analysis tools such as OLAP data cubes and web reports to enable browser and Excel pivot table access to the data.

  2. RPython high-level synthesis

    NASA Astrophysics Data System (ADS)

    Cieszewski, Radoslaw; Linczuk, Maciej

    2016-09-01

    The development of FPGA technology and the increasing complexity of applications in recent decades have forced compilers to move to higher abstraction levels. Compilers interprets an algorithmic description of a desired behavior written in High-Level Languages (HLLs) and translate it to Hardware Description Languages (HDLs). This paper presents a RPython based High-Level synthesis (HLS) compiler. The compiler get the configuration parameters and map RPython program to VHDL. Then, VHDL code can be used to program FPGA chips. In comparison of other technologies usage, FPGAs have the potential to achieve far greater performance than software as a result of omitting the fetch-decode-execute operations of General Purpose Processors (GPUs), and introduce more parallel computation. This can be exploited by utilizing many resources at the same time. Creating parallel algorithms computed with FPGAs in pure HDL is difficult and time consuming. Implementation time can be greatly reduced with High-Level Synthesis compiler. This article describes design methodologies and tools, implementation and first results of created VHDL backend for RPython compiler.

  3. Modified Synthesis of Erlotinib Hydrochloride

    PubMed Central

    Barghi, Leila; Aghanejad, Ayuob; Valizadeh, Hadi; Barar, Jaleh; Asgari, Davoud

    2012-01-01

    Purpose: An improved and economical method has been described for the synthesis of erlotinib hydrochloride, as a useful drug in treatment of non-small-cell lung cancer. Method: Erlotinib hydrochloride was synthesized in seven steps starting from 3, 4-dihydroxy benzoic acid. In this study, we were able to modify one of the key steps which involved the reduction of the 6-nitrobenzoic acid derivative to 6-aminobenzoic acid derivative. An inexpensive reagent such as ammonium formate was used as an in situ hydrogen donor in the presence of palladium/charcoal (Pd/C) instead of hydrogen gas at high pressure. Result: This proposed method proceeded with 92% yield at room temperature. Synthesis of erlotinib was completed in 7 steps with overall yield of 44%. Conclusion: From the results obtained it can be concluded that the modified method eliminated the potential danger associated with the use of hydrogen gas in the presence of flammable catalysts. It should be mentioned that the catalyst was recovered after the reaction and could be used again. PMID:24312780

  4. Metallacyclopentadienes: synthesis, structure and reactivity.

    PubMed

    Ma, Wangyang; Yu, Chao; Chen, Tianyang; Xu, Ling; Zhang, Wen-Xiong; Xi, Zhenfeng

    2017-02-20

    Metallacyclopentadienes, which possess two M-C(sp(2)) bonds and feature the structure of M(C[upper bond 1 start]R(1)[double bond, length as m-dash]CR(2)-CR(3)[double bond, length as m-dash]C[upper bond 1 end]R(4)), are an important class of five-membered metallacycles. They are considered as both reactive intermediates in the stoichiometric and catalytic transformations of organic molecules and useful precursors to main group element compounds, and have received considerable attention in organometallic chemistry, coordination chemistry and synthetic organic chemistry over the past six decades because of their unique metallacyclic structure. This review comprehensively presents the synthesis, structure and reactivity of the s-, p-, d- and f-block metallacyclopentadienes distributed in the whole periodic table. In addition, their application in synthetic organic chemistry and polymer chemistry is summarized. This review aims to be beneficial for the design and synthesis of novel metallacyclopentadienes, and for promoting the rapid development of metallacyclic chemistry.

  5. Synthesis and characterization of triangulene.

    PubMed

    Pavliček, Niko; Mistry, Anish; Majzik, Zsolt; Moll, Nikolaj; Meyer, Gerhard; Fox, David J; Gross, Leo

    2017-02-13

    Triangulene, the smallest triplet-ground-state polybenzenoid (also known as Clar's hydrocarbon), has been an enigmatic molecule ever since its existence was first hypothesized. Despite containing an even number of carbons (22, in six fused benzene rings), it is not possible to draw Kekulé-style resonant structures for the whole molecule: any attempt results in two unpaired valence electrons. Synthesis and characterization of unsubstituted triangulene has not been achieved because of its extreme reactivity, although the addition of substituents has allowed the stabilization and synthesis of the triangulene core and verification of the triplet ground state via electron paramagnetic resonance measurements. Here we show the on-surface generation of unsubstituted triangulene that consists of six fused benzene rings. The tip of a combined scanning tunnelling and atomic force microscope (STM/AFM) was used to dehydrogenate precursor molecules. STM measurements in combination with density functional theory (DFT) calculations confirmed that triangulene keeps its free-molecule properties on the surface, whereas AFM measurements resolved its planar, threefold symmetric molecular structure. The unique topology of such non-Kekulé hydrocarbons results in open-shell π-conjugated graphene fragments that give rise to high-spin ground states, potentially useful in organic spintronic devices. Our generation method renders manifold experiments possible to investigate triangulene and related open-shell fragments at the single-molecule level.

  6. Bioinspired synthesis of magnetic nanoparticles

    SciTech Connect

    David, Anand

    2009-01-01

    The synthesis of magnetic nanoparticles has long been an area of active research. Magnetic nanoparticles can be used in a wide variety of applications such as magnetic inks, magnetic memory devices, drug delivery, magnetic resonance imaging (MRI) contrast agents, and pathogen detection in foods. In applications such as MRI, particle uniformity is particularly crucial, as is the magnetic response of the particles. Uniform magnetic particles with good magnetic properties are therefore required. One particularly effective technique for synthesizing nanoparticles involves biomineralization, which is a naturally occurring process that can produce highly complex nanostructures. Also, the technique involves mild conditions (ambient temperature and close to neutral pH) that make this approach suitable for a wide variety of materials. The term 'bioinspired' is important because biomineralization research is inspired by the naturally occurring process, which occurs in certain microorganisms called 'magnetotactic bacteria'. Magnetotactic bacteria use biomineralization proteins to produce magnetite crystals having very good uniformity in size and morphology. The bacteria use these magnetic particles to navigate according to external magnetic fields. Because these bacteria synthesize high quality crystals, research has focused on imitating aspects of this biomineralization in vitro. In particular, a biomineralization iron-binding protein found in a certain species of magnetotactic bacteria, magnetospirillum magneticum, AMB-1, has been extracted and used for in vitro magnetite synthesis; Pluronic F127 gel was used to increase the viscosity of the reaction medium to better mimic the conditions in the bacteria. It was shown that the biomineralization protein mms6 was able to facilitate uniform magnetite synthesis. In addition, a similar biomineralization process using mms6 and a shorter version of this protein, C25, has been used to synthesize cobalt ferrite particles. The overall

  7. Abiogenic synthesis on terrestrial orbit

    NASA Astrophysics Data System (ADS)

    Simakov, Michael B.; Kuzicheva, Evgenia; Gontareva, Natalia

    Meteorites probably played a central role in the evolution of life. Due to the structure, they tend to adsorb organic compounds and catalyze a variety of organic reactions critical to scenarios of life’s origins. We have shown experimentally that extraterrestrial minerals can catalyze the formation of peptides and nucleotides. The present study was performed onboard different Russian space stations (BION, COSMOS, and MIR) with various duration, altitude, and radiation conditions. Irradiation of solid samples, free or admixed with certain minerals, was the major task of future space flight experiments, planned for performing onboard Russian space satellite Bion-M. The «simulated space ice conditions» experiments have shown the synthesis of simple biochemical compounds in the form of amino acid’s precursors and pyrimidine bases (uracil, cyrosine and thymine) of the nucleic acids. Our investigation dealt with further reaction of nucleic acid components to nucleotides - main components of RNA and DNA, and single aminoacids to oligopeptides. We investigated two types of reactions: (1) abiogenic synthesis of nucleotides from mixtures of nucleoside + inorganic phosphate; (2) abiogenic synthesis of dipeptides from mixtures of simple amino acids. The reaction mixture in the form of a solid film contains (1) nucleoside and dihydrogen phosphate; (2) two different amino acids. Seven different nucleosides (thymidine, cytidine, uracil, adenosine or deoxyadenosine, guanosine or deoxyguanosine) and four mixtures of aromatic (tyrosine or triptophan) and aliphatic (glycine or alanine) amino acids were investigated. Mixtures were irradiated as solid films with different sources of energy: (1) VUV-light of 145 nm; (2) high energy protons (2-6 MeV); and (3) were installed on the surface of biosputnik in outstanding container when they were exposed to the action of all spectra of the open space energy sources during the entire time of flight. We have shown experimentally that the

  8. Transductive face sketch-photo synthesis.

    PubMed

    Wang, Nannan; Tao, Dacheng; Gao, Xinbo; Li, Xuelong; Li, Jie

    2013-09-01

    Face sketch-photo synthesis plays a critical role in many applications, such as law enforcement and digital entertainment. Recently, many face sketch-photo synthesis methods have been proposed under the framework of inductive learning, and these have obtained promising performance. However, these inductive learning-based face sketch-photo synthesis methods may result in high losses for test samples, because inductive learning minimizes the empirical loss for training samples. This paper presents a novel transductive face sketch-photo synthesis method that incorporates the given test samples into the learning process and optimizes the performance on these test samples. In particular, it defines a probabilistic model to optimize both the reconstruction fidelity of the input photo (sketch) and the synthesis fidelity of the target output sketch (photo), and efficiently optimizes this probabilistic model by alternating optimization. The proposed transductive method significantly reduces the expected high loss and improves the synthesis performance for test samples. Experimental results on the Chinese University of Hong Kong face sketch data set demonstrate the effectiveness of the proposed method by comparing it with representative inductive learning-based face sketch-photo synthesis methods.

  9. Leucine stimulation of skeletal muscle protein synthesis

    SciTech Connect

    Layman, D.K.; Grogan, C.K.

    1986-03-01

    Previous work in this laboratory has demonstrated a stimulatory effect of leucine on skeletal muscle protein synthesis measured in vitro during catabolic conditions. Studies in other laboratories have consistently found this effect in diaphragm muscle, however, studies examining effects on nitrogen balance or with in vivo protein synthesis in skeletal muscle are equivocal. This experiment was designed to determine the potential of leucine to stimulate skeletal muscle protein synthesis in vivo. Male Sprague-Dawley rats weighing 200 g were fasted for 12 hrs, anesthetized, a jugular cannula inserted, and protein synthesis measured using a primed continuous infusion of /sup 14/C-tyrosine. A plateau in specific activity was reached after 30 to 60 min and maintained for 3 hrs. The leucine dose consisted of a 240 umole priming dose followed by a continuous infusion of 160 umoles/hr. Leucine infusion stimulated protein synthesis in the soleus muscle (28%) and in the red (28%) and white portions (12%) of the gastrocnemius muscle compared with controls infused with only tyrosine. The increased rates of protein synthesis were due to increased incorporation of tyrosine into protein and to decreased specific activity of the free tyrosine pool. These data indicate that infusion of leucine has the potential to stimulate in vivo protein synthesis in skeletal muscles.

  10. Synthesis of nano anatase for titanosilicate ETS-10 synthesis

    NASA Astrophysics Data System (ADS)

    Shafeque, Shihara

    Functionalized textiles present a vast and growing niche in the global textile market at US $400 billion [1, 2]. Engelhard Titanium Silicate 10 (ETS-10), a photocatalytic zeo-type material if coated on textiles, is expected to impart useful properties similar to TiO2, such as stain-resistant, odor repellant, bactericidal and enhanced UV protection [3, 4]. Typically, small ETS-10 crystals of size ˜300-800 nm are synthesized using solid titania (e.g., anatase or P25) sources [5, 6, 7]. However, smaller ETS-10 crystals are required for a uniform surface coating with highly effective surface area. The dissolution of titania particles (i.e., their size) is hypothesized to be important in small ETS-10 crystal formation [5, 6, 7]. Nano anatase was synthesized by modification of two methods: direct precipitation [7] and sol-gel synthesis [3]. Analysis by XRD confirmed that both methods produced nano anatase of crystallite size ˜4-5 nm. However, FE-SEM analysis showed that product from direct precipitation, existed as intergrown spheroidal particles with size ˜1.0 mum. These particles dispersed poorly in deionized water. Therefore, the best nano anatase samples were from sol-gel synthesis in two forms, dry powder and colloidal anatase. ETS-10 synthesis was investigated using two methods adopted from literature [6, 7]. The method of Yoon and co-workers [7], with nano anatase in a molar composition of 5.5TEOS: TiO2: 8.4NaOH: 1.43KF: 350H2O: 2.2H2SO4 produced unknown phase(s) with some ETS-10 and quartz. Using colloidal anatase with molar composition 5.5TEOS:1.0TiO 2:8.4NaOH:1.43KF:400H2O:2.2H2SO4 also produced unknown phase(s). The method of Anderson and co-workers [6] with nano anatase powder in a molar composition of 5.5SiO2: TiO 2: 5.2Na2O: 0.5K2O: 113H2O produced quartz with ETS-10 impurity. When colloidal anatase was used, with molar composition TiO2:5.5SiO2:5.2Na2O:0.5K2O:332H 2O, unreacted anatase and quartz were formed. It was hypothesized that the very low

  11. Accelerating spirocyclic polyketide synthesis using flow chemistry.

    PubMed

    Newton, Sean; Carter, Catherine F; Pearson, Colin M; de C Alves, Leandro; Lange, Heiko; Thansandote, Praew; Ley, Steven V

    2014-05-05

    Over the past decade, the integration of synthetic chemistry with flow processing has resulted in a powerful platform for molecular assembly that is making an impact throughout the chemical community. Herein, we demonstrate the extension of these tools to encompass complex natural product synthesis. We have developed a number of novel flow-through processes for reactions commonly encountered in natural product synthesis programs to achieve the first total synthesis of spirodienal A and the preparation of spirangien A methyl ester. Highlights of the synthetic route include an iridium-catalyzed hydrogenation, iterative Roush crotylations, gold-catalyzed spiroketalization and a late-stage cis-selective reduction.

  12. Synthesis of morphine alkaloids and derivatives.

    PubMed

    Rinner, Uwe; Hudlicky, Tomas

    2012-01-01

    This review summarizes recent developments in the total synthesis of morphine alkaloids and some of the semisynthetic derivatives. The literature is covered for the period of 5 years after the publication of the last review in 2005. The syntheses that appeared in this period are covered in detail and are placed in the context of all syntheses of opiate alkaloids since the original one published by Gates in 1952. The introduction covers the historical aspects of total synthesis of these alkaloids. The synthesis of some of the medicinally useful derivatives is reviewed in the last section along with some of the methodology required for their preparation.

  13. [Meta-synthesis: a research methodology].

    PubMed

    Carrillo-González, Gloria M; Gómez-Ramírez, Olga J; Vargas-Rosero, Elizabeth

    2007-01-01

    This article resulted from a bibliographical review concerning meta-synthesis, considered to be a novel methodology in health science research. Meta-synthesis' importance lies in evaluating high complex scientific evidence from qualitative research and strengthening a discipline's body of knowledge when constructing, describing or explaining related theories. Several authors' definitions of meta-synthesis are presented. They coincide in stating that its purpose is to enhance interpreting an outcome by integrating the findings from qualitative research and thus have an impact on support, research and proposals in resolving problems regarding nursing practice. Some criteria to be born in mind when applying this methodology are also mentioned.

  14. Green chemistry oriented organic synthesis in water.

    PubMed

    Simon, Marc-Olivier; Li, Chao-Jun

    2012-02-21

    The use of water as solvent features many benefits such as improving reactivities and selectivities, simplifying the workup procedures, enabling the recycling of the catalyst and allowing mild reaction conditions and protecting-group free synthesis in addition to being benign itself. In addition, exploring organic chemistry in water can lead to uncommon reactivities and selectivities complementing the organic chemists' synthetic toolbox in organic solvents. Studying chemistry in water also allows insight to be gained into Nature's way of chemical synthesis. However, using water as solvent is not always green. This tutorial review briefly discusses organic synthesis in water with a Green Chemistry perspective.

  15. Synthesis of cyanopyridine based conjugated polymer

    PubMed Central

    Hemavathi, B.; Ahipa, T.N.; Pillai, Saju; Pai, Ranjith Krishna

    2016-01-01

    This data file contains the detailed synthetic procedure for the synthesis of two new cyanopyridine based conjugated polymer P1 and P2 along with the synthesis of its monomers. The synthesised polymers can be used for electroluminescence and photovoltaic (PV) application. The physical data of the polymers are provided in this data file along with the morphological data of the polymer thin films. The data provided here are in association with the research article entitled ‘Cyanopyridine based conjugated polymer-synthesis and characterisation’ (Hemavathi et al., 2015) [3]. PMID:27158642

  16. Synthesis of mullite powders by acrylamide polymerization.

    SciTech Connect

    Sin, A.; Picciolo, J. J.; Lee, R. H.; Gutierrez-Mora, F.; Goretta, K. C.; Energy Technology; INPG-CNRS

    2001-09-01

    Mullite (3Al{sub 2}O{sub 3} {center_dot} 2SiO{sub 2}) ceramics and composites are widely used. Synthesis of mullite powders, especially those that can be readily sintered, remains a focus of much current research. In support of recent efforts to fabricate mullite fibrous monoliths and to use superplastic flow to join ceramics, we have looked to synthesize reactive mullite powders. Recent advances in application of acrylamide polymers to ceramic synthesis offer promise of obtaining large quantities of high-quality powder at relatively low cost. We report here on synthesis from acrylamide monomers of mullite powders of two interesting particle sizes.

  17. Coinage Metal Hydrides: Synthesis, Characterization, and Reactivity.

    PubMed

    Jordan, Abraham J; Lalic, Gojko; Sadighi, Joseph P

    2016-08-10

    Hydride complexes of copper, silver, and gold encompass a broad array of structures, and their distinctive reactivity has enabled dramatic recent advances in synthesis and catalysis. This Review summarizes the synthesis, characterization, and key stoichiometric reactions of isolable or observable coinage metal hydrides. It discusses catalytic processes in which coinage metal hydrides are known or probable intermediates, and presents mechanistic studies of selected catalytic reactions. The purpose of this Review is to convey how developments in coinage metal hydride chemistry have led to new organic transformations, and how developments in catalysis have in turn inspired the synthesis of reactive new complexes.

  18. Synthesis of alpha-amino acids

    DOEpatents

    Davis, Jr., Jefferson W.

    1983-01-01

    A method for synthesizing alpha amino acids proceding through novel intermediates of the formulas: R.sub.1 R.sub.2 C(OSOCl)CN, R.sub.1 R.sub.2 C(Cl)CN and [R.sub.1 R.sub.2 C(CN)O].sub.2 SO wherein R.sub.1 and R.sub.2 are each selected from hydrogen monovalent substituted and unsubstituted hydrocarbon radicals of 1 to 12 carbon atoms. The use of these intermediates allows the synthesis steps to be exothermic and results in an overall synthesis method which is faster than the synthesis methods of the prior art.

  19. Synthesis of alpha-amino acids

    DOEpatents

    Davis, Jr., Jefferson W.

    1983-01-01

    A method for synthesizing alpha amino acids proceeding through novel intermediates of the formulas: R.sub.1 R.sub.2 C(OSOCl)CN, R.sub.1 R.sub.2 C(Cl)CN and [R.sub.1 R.sub.2 C(CN)O].sub.2 SO wherein R.sub.1 and R.sub.2 are each selected from hydrogen monovalent substituted and unsubstituted hydrocarbon radicals of 1 to 12 carbon atoms. The use of these intermediates allows the synthesis steps to be exothermic and results in an overall synthesis method which is faster than the synthesis methods of the prior art.

  20. Synthesis of the Enantiomers of Tedanalactam and the First Total Synthesis and Configurational Assignment of (+)-Piplaroxide.

    PubMed

    Romero-Ibañez, Julio; Xochicale-Santana, Leonardo; Quintero, Leticia; Fuentes, Lilia; Sartillo-Piscil, Fernando

    2016-04-22

    Highlighting the recently established methodology for the direct synthesis of glycidic amides from tertiary allyl amines, the synthesis of the enantiomers of tedanalactam were completed in two steps from the corresponding chiral dihydropiperidine. Additionally, the (+)- and (-)-enantiomers of piplaroxide were obtained from their respective tedanalactam precursor, and the absolute configuration of the naturally occurring (+)-piplaroxide was determined. The present approach represents not only the shortest synthesis of (-)-tedanalactam but also the first total synthesis of (+)-piplaroxide, a repellent against the leafcutter ant Atta cephalotes.

  1. Synthesis

    SciTech Connect

    Schimel, David; Janetos, Anthony C.; Backlund, Peter; Hatfield, Jerry; Ryan, Mike; Archer, Steven; Lettenmaier, D. P.

    2008-05-01

    This section synthesizes information from those sectoral chapters in the book to address a series of questions that were posed by the CCSP agencies in the prospectus for this report and formulate a set of overaching conclusions.

  2. Fluid Mechanics Optimising Organic Synthesis

    NASA Astrophysics Data System (ADS)

    Leivadarou, Evgenia; Dalziel, Stuart

    2015-11-01

    The Vortex Fluidic Device (VFD) is a new ``green'' approach in the synthesis of organic chemicals with many industrial applications in biodiesel generation, cosmetics, protein folding and pharmaceutical production. The VFD is a rapidly rotating tube that can operate with a jet feeding drops of liquid reactants to the base of the tube. The aim of this project is to explain the fluid mechanics of the VFD that influence the rate of reactions. The reaction rate is intimately related to the intense shearing that promotes collision between reactant molecules. In the VFD, the highest shears are found at the bottom of the tube in the Rayleigh and the Ekman layer and at the walls in the Stewardson layers. As a step towards optimising the performance of the VFD we present experiments conducted in order to establish the minimum drop volume and maximum rotation rate for maximum axisymmetric spreading without fingering instability. PhD candidate, Department of Applied Mathematics and Theoretical Physics.

  3. GASP- GENERAL AVIATION SYNTHESIS PROGRAM

    NASA Technical Reports Server (NTRS)

    Galloway, T. L.

    1994-01-01

    The General Aviation Synthesis Program, GASP, was developed to perform tasks generally associated with the preliminary phase of aircraft design. GASP gives the analyst the capability of performing parametric studies in a rapid manner during preliminary design efforts. During the development of GASP, emphasis was placed on small fixed-wing aircraft employing propulsion systems varying from a single piston engine with a fixed pitch propeller through twin turboprop/turbofan systems as employed in business or transport type aircraft. The program is comprised of modules representing the various technical disciplines of design, integrated into a computational flow which ensures that the interacting effects of design variables are continuously accounted for in the aircraft sizing procedures. GASP provides a useful tool for comparing configurations, assessing aircraft performance and economics, and performing tradeoff and sensitivity studies. By utilizing GASP, the impact of various aircraft requirements and design factors may be studied in a systematic manner, with benefits being measured in terms of overall aircraft performance and economics. The GASP program consists of a control module and six "technology" submodules which perform the various independent studies required in the design of general aviation or small transport type aircraft. The six technology modules include geometry, aerodynamics, propulsion, weight and balance, mission analysis, and economics. The geometry module calculates the dimensions of the synthesized aircraft components based on such input parameters as number of passengers, aspect ratio, taper ratio, sweep angles, and thickness of wing and tail surfaces. The aerodynamics module calculates the various lift and drag coefficients of the synthesized aircraft based on inputs concerning configuration geometry, flight conditions, and type of high lift device. The propulsion module determines the engine size and performance for the synthesized aircraft

  4. Algorithmic synthesis using Python compiler

    NASA Astrophysics Data System (ADS)

    Cieszewski, Radoslaw; Romaniuk, Ryszard; Pozniak, Krzysztof; Linczuk, Maciej

    2015-09-01

    This paper presents a python to VHDL compiler. The compiler interprets an algorithmic description of a desired behavior written in Python and translate it to VHDL. FPGA combines many benefits of both software and ASIC implementations. Like software, the programmed circuit is flexible, and can be reconfigured over the lifetime of the system. FPGAs have the potential to achieve far greater performance than software as a result of bypassing the fetch-decode-execute operations of traditional processors, and possibly exploiting a greater level of parallelism. This can be achieved by using many computational resources at the same time. Creating parallel programs implemented in FPGAs in pure HDL is difficult and time consuming. Using higher level of abstraction and High-Level Synthesis compiler implementation time can be reduced. The compiler has been implemented using the Python language. This article describes design, implementation and results of created tools.

  5. Energy management and vehicle synthesis

    NASA Technical Reports Server (NTRS)

    Czysz, P.; Murthy, S. N. B.

    1995-01-01

    The major drivers in the development of launch vehicles for the twenty-first century are reduction in cost of vehicles and operations, continuous reusability, mission abort capability with vehicle recovery, and readiness. One approach to the design of such vehicles is to emphasize energy management and propulsion as being the principal means of improvements given the available industrial capability and the required freedom in selecting configuration concept geometries. A methodology has been developed for the rational synthesis of vehicles based on the setting up and utilization of available data and projections, and a reference vehicle. The application of the methodology is illustrated for a single stage to orbit (SSTO) with various limits for the use of airbreathing propulsion.

  6. Solution synthesis of germanium nanocrystals

    DOEpatents

    Gerung, Henry; Boyle, Timothy J.; Bunge, Scott D.

    2009-09-22

    A method for providing a route for the synthesis of a Ge(0) nanometer-sized material from. A Ge(II) precursor is dissolved in a ligand heated to a temperature, generally between approximately 100.degree. C. and 400.degree. C., sufficient to thermally reduce the Ge(II) to Ge(0), where the ligand is a compound that can bond to the surface of the germanium nanomaterials to subsequently prevent agglomeration of the nanomaterials. The ligand encapsulates the surface of the Ge(0) material to prevent agglomeration. The resulting solution is cooled for handling, with the cooling characteristics useful in controlling the size and size distribution of the Ge(0) materials. The characteristics of the Ge(II) precursor determine whether the Ge(0) materials that result will be nanocrystals or nanowires.

  7. Abiotic synthesis of fatty acids

    NASA Technical Reports Server (NTRS)

    Leach, W. W.; Nooner, D. W.; Oro, J.

    1978-01-01

    The formation of fatty acids by Fischer-Tropsch-type synthesis was investigated with ferric oxide, ammonium carbonate, potassium carbonate, powdered Pueblito de Allende carbonaceous chondrite, and filings from the Canyon Diablo meteorite used as catalysts. Products were separated and identified by gas chromatography and mass spectrometry. Iron oxide, Pueblito de Allende chondrite, and Canyon Diablo filings in an oxidized catalyst form yielded no fatty acids. Canyon Diablo filings heated overnight at 500 C while undergoing slow purging by deuterium produced fatty acids only when potassium carbonate was admixed; potassium carbonate alone also produced these compounds. The active catalytic combinations gave relatively high yields of aliphatic and aromatic hydrocarbons; substantial amounts of n-alkenes were almost invariably observed when fatty acids were produced; the latter were in the range C6 to C18, with maximum yield in C9 or 10.

  8. Combustion synthesis continuous flow reactor

    DOEpatents

    Maupin, Gary D.; Chick, Lawrence A.; Kurosky, Randal P.

    1998-01-01

    The present invention is a reactor for combustion synthesis of inorganic powders. The reactor includes a reaction vessel having a length and a first end and a second end. The reaction vessel further has a solution inlet and a carrier gas inlet. The reactor further has a heater for heating both the solution and the carrier gas. In a preferred embodiment, the reaction vessel is heated and the solution is in contact with the heated reaction vessel. It is further preferred that the reaction vessel be cylindrical and that the carrier gas is introduced tangentially into the reaction vessel so that the solution flows helically along the interior wall of the reaction vessel. As the solution evaporates and combustion produces inorganic material powder, the carrier gas entrains the powder and carries it out of the reactor.

  9. The greener synthesis of nanoparticles.

    PubMed

    Kharissova, Oxana V; Dias, H V Rasika; Kharisov, Boris I; Pérez, Betsabee Olvera; Pérez, Victor M Jiménez

    2013-04-01

    In this review, we examine 'greener' routes to nanoparticles of zerovalent metals, metal oxides, and salts with an emphasis on recent developments. Products from nature or those derived from natural products, such as extracts of various plants or parts of plants, tea, coffee, banana, simple amino acids, as well as wine, table sugar and glucose, have been used as reductants and as capping agents during synthesis. Polyphenols found in plant material often play a key role in these processes. The techniques involved are simple, environmentally friendly, and generally one-pot processes. Tea extracts with high polyphenol content act as both chelating/reducing and capping agents for nanoparticles. We discuss the key materials used in the field: silver, gold, iron, metal alloys, oxides, and salts.

  10. Synthesis of stiffened conical shells.

    NASA Technical Reports Server (NTRS)

    Thornton, W. A.

    1972-01-01

    The development of a method to effect the automated minimum weight design of ring and stringer stiffened shells is presented. Membrane theory is used for the shell prebuckling analysis. The buckling analysis is based upon an arbitrary shell of revolution computer program. The structural analysis includes both buckling and yielding modes of failure. The synthesis involves the coupling of an exterior penalty function with a method for the unconstrained minimization of a function comprised of a sum of squares. Results of the application of the method to the design of the Viking Aeroshell cone are presented. The least weight Viking Aeroshell appears to be an all magnesium shell with ring stiffeners of hollow circular cross section. Because the method incorporates a general shell of revolution buckling analysis, it can be readily modified and applied to the design of any axisymmetrically loaded uniformly stiffened shell of revolution for which a membrane prebuckling solution exists.

  11. Combustion synthesis continuous flow reactor

    DOEpatents

    Maupin, G.D.; Chick, L.A.; Kurosky, R.P.

    1998-01-06

    The present invention is a reactor for combustion synthesis of inorganic powders. The reactor includes a reaction vessel having a length and a first end and a second end. The reaction vessel further has a solution inlet and a carrier gas inlet. The reactor further has a heater for heating both the solution and the carrier gas. In a preferred embodiment, the reaction vessel is heated and the solution is in contact with the heated reaction vessel. It is further preferred that the reaction vessel be cylindrical and that the carrier gas is introduced tangentially into the reaction vessel so that the solution flows helically along the interior wall of the reaction vessel. As the solution evaporates and combustion produces inorganic material powder, the carrier gas entrains the powder and carries it out of the reactor. 10 figs.

  12. Synthesis of nanoparticles using ethanol

    DOEpatents

    Wang, Jia Xu

    2017-01-24

    The present disclosure relates to methods for producing nanoparticles. The nanoparticles may be made using ethanol as the solvent and the reductant to fabricate noble-metal nanoparticles with a narrow particle size distributions, and to coat a thin metal shell on other metal cores. With or without carbon supports, particle size is controlled by fine-tuning the reduction power of ethanol, by adjusting the temperature, and by adding an alkaline solution during syntheses. The thickness of the added or coated metal shell can be varied easily from sub-monolayer to multiple layers in a seed-mediated growth process. The entire synthesis of designed core-shell catalysts can be completed using metal salts as the precursors with more than 98% yield; and, substantially no cleaning processes are necessary apart from simple rinsing. Accordingly, this method is considered to be a "green" chemistry method.

  13. Electrochemical synthesis of multisegmented nanowires

    SciTech Connect

    Kok, Kuan-Ying; Ng, Inn-Khuan; Saidin, Nur Ubaidah

    2012-11-27

    Electrochemical deposition has emerged as a promising route for nanostructure fabrication in recent years due to the many inherent advantages it possesses. This study focuses on the synthesis of high-aspect-ratio multisegmented Au/Ni nanowires using template-directed sequential electrochemical deposition techniques. By selectively removing the Ni segments in the nanowires, high-yield of pure gold nanorods of predetermined lengths was obtained. Alternatively, the sacrificial Ni segments in the nanowires can be galvanically displaced with Bi and Te to form barbells structures with Bi{sub x}Te{sub y} nanotubes attached to neighbouring gold segments. Detailed studies on the nanostructures obtained were carried out using various microscopy, diffraction and probebased techniques for structural, morphological and chemical characterizations.

  14. Synthesis gas method and apparatus

    DOEpatents

    Kelly, Sean M.; Kromer, Brian R.; Litwin, Michael M.; Rosen, Lee J.; Christie, Gervase Maxwell; Wilson, Jamie; Kosowski, Lawrence W; Robinson, Charles

    2015-11-06

    A method and apparatus for producing a synthesis gas product having one or more oxygen transport membrane elements thermally coupled to one or more catalytic reactors such that heat generated from the oxygen transport membrane element supplies endothermic heating requirements for steam methane reforming reactions occurring within the catalytic reactor through radiation and convention heat transfer. A hydrogen containing stream containing no more than 20 percent methane is combusted within the oxygen transport membrane element to produce the heat and a heated combustion product stream. The heated combustion product stream is combined with a reactant stream to form a combined stream that is subjected to the reforming within the catalytic reactor. The apparatus may include modules in which tubular membrane elements surround a central reactor tube.

  15. Synthesis gas method and apparatus

    DOEpatents

    Kelly, Sean M.; Kromer, Brian R.; Litwin, Michael M.; Rosen, Lee J.; Christie, Gervase Maxwell; Wilson, Jamie R.; Kosowski, Lawrence W.; Robinson, Charles

    2013-01-08

    A method and apparatus for producing a synthesis gas product having one or more oxygen transport membrane elements thermally coupled to one or more catalytic reactors such that heat generated from the oxygen transport membrane element supplies endothermic heating requirements for steam methane reforming reactions occurring within the catalytic reactor through radiation and convention heat transfer. A hydrogen containing stream containing no more than 20 percent methane is combusted within the oxygen transport membrane element to produce the heat and a heated combustion product stream. The heated combustion product stream is combined with a reactant stream to form a combined stream that is subjected to the reforming within the catalytic reactor. The apparatus may include modules in which tubular membrane elements surround a central reactor tube.

  16. Template Synthesis of Carbon Nanotubules

    NASA Astrophysics Data System (ADS)

    Tee, J. C.; Sanip, S. M.; Aziz, M.; Ismail, A. F.

    2010-03-01

    The template synthesis of carbon nanostructures formed in porous anodic aluminium oxide (AAO) template with a pore size of 200 nm by a liquid phase impregnation of the template with a polymer, polyfurfuryl alcohol, followed by carbonization is studied. The temperatures of exposure to furfuryl alcohol vapour were varied between 50 and 70° C. The resultant carbon nanotubules formed were hollow with open ends having diameter ranging from 220-300 nm which is in agreement with the pore size of the template used. The BET surface area was found to increase from 11.64 m2/g before pyrolysis to 90.19 m2/g after pyrolysis as a result of the formation of carbon nanotubules.

  17. High pressure synthesis gas fermentation

    SciTech Connect

    Not Available

    1991-01-01

    The purpose of this research project is to build and test a pressure fermentation system for the production of ethanol from synthesis gas. The fermenters, pumps, controls, and analytical system will be procured or fabricated and assembled in our laboratory. This system will then be used to determine the effects of high pressure on growth and ethanol production by clostridium ljungdahlii. The limits of cell concentration and mass transport relationships will be found in continuous stirred tank reactor and immobilized cell reactors. The minimum retention times and reactor volumes will be found for ethanol production in these reactors. Retention times of a few seconds are expected to result from these experiments. 2 figs., 2 tabs.

  18. Abscisic Acid Synthesis and Response

    PubMed Central

    Finkelstein, Ruth

    2013-01-01

    Abscisic acid (ABA) is one of the “classical” plant hormones, i.e. discovered at least 50 years ago, that regulates many aspects of plant growth and development. This chapter reviews our current understanding of ABA synthesis, metabolism, transport, and signal transduction, emphasizing knowledge gained from studies of Arabidopsis. A combination of genetic, molecular and biochemical studies has identified nearly all of the enzymes involved in ABA metabolism, almost 200 loci regulating ABA response, and thousands of genes regulated by ABA in various contexts. Some of these regulators are implicated in cross-talk with other developmental, environmental or hormonal signals. Specific details of the ABA signaling mechanisms vary among tissues or developmental stages; these are discussed in the context of ABA effects on seed maturation, germination, seedling growth, vegetative stress responses, stomatal regulation, pathogen response, flowering, and senescence. PMID:24273463

  19. POPULATION SYNTHESIS AND GAMMA RAY BURST PROGENITORS

    SciTech Connect

    C. L. FREYER

    2000-12-11

    Population synthesis studies of binaries are always limited by a myriad of uncertainties from the poorly understood effects of binary mass transfer and common envelope evolution to the many uncertainties that still remain in stellar evolution. But the importance of these uncertainties depends both upon the objects being studied and the questions asked about these objects. Here I review the most critical uncertainties in the population synthesis of gamma-ray burst progenitors. With a better understanding of these uncertainties, binary population synthesis can become a powerful tool in understanding, and constraining, gamma-ray burst models. In turn, as gamma-ray bursts become more important as cosmological probes, binary population synthesis of gamma-ray burst progenitors becomes an important tool in cosmology.

  20. Mathematical programming formulations for satellite synthesis

    NASA Technical Reports Server (NTRS)

    Bhasin, Puneet; Reilly, Charles H.

    1987-01-01

    The problem of satellite synthesis can be described as optimally allotting locations and sometimes frequencies and polarizations, to communication satellites so that interference from unwanted satellite signals does not exceed a specified threshold. In this report, mathematical programming models and optimization methods are used to solve satellite synthesis problems. A nonlinear programming formulation which is solved using Zoutendijk's method and a gradient search method is described. Nine mixed integer programming models are considered. Results of computer runs with these nine models and five geographically compatible scenarios are presented and evaluated. A heuristic solution procedure is also used to solve two of the models studied. Heuristic solutions to three large synthesis problems are presented. The results of our analysis show that the heuristic performs very well, both in terms of solution quality and solution time, on the two models to which it was applied. It is concluded that the heuristic procedure is the best of the methods considered for solving satellite synthesis problems.

  1. A novel asymmetric synthesis of cinacalcet hydrochloride

    PubMed Central

    Gorentla, Laxminarasimhulu; Dubey, Pramod K

    2012-01-01

    Summary A novel route to asymmetric synthesis of cinacalcet hydrochloride by the application of (R)-tert-butanesulfinamide and regioselective N-alkylation of the naphthyl ethyl sulfinamide intermediate is described. PMID:23019473

  2. Anthrax carbohydrates, synthesis and uses thereof

    DOEpatents

    Carlson, Russell W.; Boons, Geert-Jan; Quinn, Conrad; Vasan, Mahalakshmi; Wolfert, Margreet A.; Choudhury, Biswa; Kannenberg, Elmar; Leoff, Christine; Mehta, Alok; Saile, Elke; Rauvolfova, Jana; Wilkins, Patricia; Harvey, Alex J.

    2013-04-16

    The present invention presents the isolation, characterization and synthesis of oligosaccharides of Bacillus anthracis. Also presented are antibodies that bind to such saccharide moieties and various methods of use for such saccharide moieties and antibodies.

  3. Synthesis of exemestane labelled with (13)C.

    PubMed

    Fontana, Erminia; Pignatti, Alberto; Giribone, Danilo; Di Salle, Enrico

    2008-08-01

    The synthesis of exemestane Aromasin, an irreversible steroidal aromatase inhibitor, specifically labelled with (13)C is reported. The preparation of [(13)C(3)]exemestane was achieved according to an eight-step procedure starting from the commercially available testosterone.

  4. Microwave chemistry for inorganic nanomaterials synthesis.

    PubMed

    Bilecka, Idalia; Niederberger, Markus

    2010-08-01

    This Feature Article gives an overview of microwave-assisted liquid phase routes to inorganic nanomaterials. Whereas microwave chemistry is a well-established technique in organic synthesis, its use in inorganic nanomaterials' synthesis is still at the beginning and far away from having reached its full potential. However, the rapidly growing number of publications in this field suggests that microwave chemistry will play an outstanding role in the broad field of Nanoscience and Nanotechnology. This article is not meant to give an exhaustive overview of all nanomaterials synthesized by the microwave technique, but to discuss the new opportunities that arise as a result of the unique features of microwave chemistry. Principles, advantages and limitations of microwave chemistry are introduced, its application in the synthesis of different classes of functional nanomaterials is discussed, and finally expected benefits for nanomaterials' synthesis are elaborated.

  5. Chronological protein synthesis in regenerating rat liver.

    PubMed

    He, Jinjun; Hao, Shuai; Zhang, Hao; Guo, Fuzheng; Huang, Lingyun; Xiao, Xueyuan; He, Dacheng

    2015-07-01

    Liver regeneration has been studied for decades; however, its regulation remains unclear. In this study, we report a dynamic tracing of protein synthesis in rat regenerating liver with a new proteomic technique, (35) S in vivo labeling analysis for dynamic proteomics (SiLAD). Conventional proteomic techniques typically measure protein alteration in accumulated amounts. The SiLAD technique specifically detects protein synthesis velocity instead of accumulated amounts of protein through (35) S pulse labeling of newly synthesized proteins, providing a direct way for analyzing protein synthesis variations. Consequently, protein synthesis within short as 30 min was visualized and protein regulations in the first 8 h of regenerating liver were dynamically traced. Further, the 3.5-5 h post partial hepatectomy (PHx) was shown to be an important regulatory turning point by acute regulation of many proteins in the initiation of liver regeneration.

  6. Protein Synthesis--An Interactive Game.

    ERIC Educational Resources Information Center

    Clements, Lee Ann J.; Jackson, Karen E.

    1998-01-01

    Describes an interactive game designed to help students see and understand the dynamic relationship between DNA, RNA, and proteins. Appropriate for either a class or laboratory setting, following a lecture session about protein synthesis. (DDR)

  7. DIFMAP: an interactive program for synthesis imaging.

    NASA Astrophysics Data System (ADS)

    Shepherd, M. C.; Pearson, T. J.; Taylor, G. B.

    1994-05-01

    DIFMAP is a new interactive program for synthesis imaging. It includes data display, data editing, selfcalibration, imaging, and deconvolution. The program, written in ANSI C, runs on UNIX workstations.

  8. BP: synthesis and properties of boron phosphide

    NASA Astrophysics Data System (ADS)

    Woo, Katherine; Lee, Kathleen; Kovnir, Kirill

    2016-07-01

    Cubic boron phosphide, BP, is notorious for its difficult synthesis, thus preventing it from being a widely used material in spite of having numerous favorable technological properties. In the current work, three different methods of synthesis are developed and compared: from the high temperature reaction of elements, Sn flux assisted synthesis, and a solid state metathesis reaction. Structural and optical properties of the products synthesized from the three methods were thoroughly characterized. Solid state metathesis is shown to be the cleanest and most efficient method in terms of reaction temperature and time. Synthesis by Sn flux resulted in a novel Sn-doped BP compound. Undoped BP samples exhibit an optical bandgap of ∼2.2 eV while Sn-doped BP exhibits a significantly smaller bandgap of 1.74 eV. All synthesized samples show high stability in concentrated hydrochloric acid, saturated sodium hydroxide solutions, and fresh aqua regia.

  9. Chemical protein synthesis (CPS) meeting 2013.

    PubMed

    Metanis, Norman

    2013-07-22

    Building bonds in Vienna: The Chemical Protein Synthesis meeting recently took place at the University of Vienna, Austria. This report describes the event and highlights the science presented over the four days.

  10. Synthesis and Spectra of Vanadium Complexes.

    ERIC Educational Resources Information Center

    Ophardt, Charles E.; Stupgia, Sean

    1984-01-01

    Describes an experiment which illustrates simple synthetic techniques, redox principles in synthesis reactions, interpretation of visible spectra using Orgel diagrams, and the spectrochemical series. The experiment is suitable for the advanced undergraduate inorganic chemistry laboratory. (JN)

  11. Enzymatic synthesis of lipid II and analogues.

    PubMed

    Huang, Lin-Ya; Huang, Shih-Hsien; Chang, Ya-Chih; Cheng, Wei-Chieh; Cheng, Ting-Jen R; Wong, Chi-Huey

    2014-07-28

    The emergence of antibiotic resistance has prompted active research in the development of antibiotics with new modes of action. Among all essential bacterial proteins, transglycosylase polymerizes lipid II into peptidoglycan and is one of the most favorable targets because of its vital role in peptidoglycan synthesis. Described in this study is a practical enzymatic method for the synthesis of lipid II, coupled with cofactor regeneration, to give the product in a 50-70% yield. This development depends on two key steps: the overexpression of MraY for the synthesis of lipid I and the use of undecaprenol kinase for the preparation of polyprenol phosphates. This method was further applied to the synthesis of lipid II analogues. It was found that MraY and undecaprenol kinase can accept a wide range of lipids containing various lengths and configurations. The activity of lipid II analogues for bacterial transglycolase was also evaluated.

  12. Synthesis of strigolactones, a strategic account.

    PubMed

    Zwanenburg, Binne; Ćavar Zeljković, Sanja; Pospíšil, Tomáš

    2016-01-01

    Strigolactones (SLs) constitute a new class of plant hormones that have received growing interest in recent years. They firstly became known as signalling molecules for host recognition by parasitic plants, and for symbiosis of plants with arbuscular mycorrhizal fungi. Furthermore, they are involved in numerous physiological processes in plants, such as the regulation of plant architecture and the response to abiotic factors. SLs are produced by plants in extremely low quantities, and they may be unstable during the purification process. Therefore, their total synthesis is highly relevant for confirming the structures assigned on the basis of spectroscopic and other physical data. A second important theme in SL research is the design and synthesis of SL analogues that have a simplified structure while still featuring the essential bioproperties. This review summarises the strategy and synthesis of naturally occurring SLs, and the design and synthesis of SL analogues with appreciable bioactivity.

  13. Total Synthesis of the Proposed Banyasin A

    NASA Astrophysics Data System (ADS)

    Gao, Xuguang; Ren, Qi; Choi, Sun; Xu, Zhengshuang; Ye, Tao

    2015-03-01

    The first total synthesis of four possible isomers of a molecule possessing the stereochemistry proposed for banyasin A is described. The structure synthesized appears to be different from that of the natural product.

  14. Total synthesis of alkyl citrate natural products.

    PubMed

    Rizzacasa, Mark A; Sturgess, Dayna

    2014-03-07

    This review highlights the synthesis of members of the alkyl citrate family of natural products. The focus is on the stereoselective construction of the alkyl citrate moiety common to these compounds.

  15. Green Synthesis of Nanocrystals and Nanocomposites

    EPA Science Inventory

    Metal nanomaterials have attracted considerable attention because of their unique magnetic, optical, electrical, and catalytic properties and their potential applications in nanoelectronics as well as in various wet chemical synthesis methods. There is also great interest in synt...

  16. Materials synthesis: Two-dimensional gallium nitride

    NASA Astrophysics Data System (ADS)

    Koratkar, Nikhil A.

    2016-11-01

    Graphene is used as a capping sheet to synthesize 2D gallium nitride by means of migration-enhanced encapsulation growth. This technique may allow the stabilization of 2D materials that are not amenable to synthesis by traditional methods.

  17. Applications of computer graphics to aircraft synthesis

    NASA Technical Reports Server (NTRS)

    Carmichael, R. L.; Putnam, R.

    1975-01-01

    The history of the development of an aircraft configuration synthesis program using interactive computer graphics was described. A system based on time-sharing was compared to two different concepts based on distributed computing.

  18. Synthesis Of Benzoxazole Monomers And Polymers

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M.; Connell, John W.; Smith, Joseph G., Jr.

    1994-01-01

    Di(hydroxyphenyl)benzoxazoles synthesized, then polymerized with aromatic dihalides. In comparison with previous routes to synthesis of polybenzoxazoles, this is simpler and more economical. New polybenzoxazoles may prove useful as adhesives, coatings, films, membranes, molding compounds, and composite matrices.

  19. Phosphatidic Acid Synthesis in Bacteria

    PubMed Central

    Yao, Jiangwei; Rock, Charles O.

    2012-01-01

    Membrane phospholipid synthesis is a vital facet of bacterial physiology. Although the spectrum of phospholipid headgroup structures produced by bacteria is large, the key precursor to all of these molecules is phosphatidic acid (PtdOH). Glycerol-3-phosphate derived from the glycolysis via glycerol-phosphate synthase is the universal source for the glycerol backbone of PtdOH. There are two distinct families of enzymes responsible for the acylation of the 1-position of glycerol-3-phosphate. The PlsB acyltransferase was discovered in Escherichia coli, and homologs are present in many eukaryotes. This protein family primarily uses acyl-acyl carrier protein (ACP) endproducts of fatty acid synthesis as acyl donors, but may also use acyl-CoA derived from exogenous fatty acids. The second protein family, PlsY, is more widely distributed in bacteria and utilizes the unique acyl donor, acyl-phosphate, which is produced from acyl-ACP by the enzyme PlsX. The acylation of the 2-position is carried out by members of the PlsC protein family. All PlsCs use acyl-ACP as the acyl donor, although the PlsCs of the γ-proteobacteria also may use acyl-CoA. Phospholipid headgroups are precursors in the biosynthesis of other membrane-associated molecules and the diacylglycerol product of these reactions is converted to PtdOH by one of two distinct families of lipid kinases. The central importance of the de novo and recycling pathways to PtdOH in cell physiology suggest these enzymes are suitable targets for the development of antibacterial therapeutics in Gram-positive pathogens. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism. PMID:22981714

  20. Microchannel systems for fine organic synthesis

    NASA Astrophysics Data System (ADS)

    Makarshin, L. L.; Pai, Z. P.; Parmon, V. N.

    2016-02-01

    Characteristic features of application of microchannel systems in organic synthesis are analyzed. The advantages of such systems over conventional chemical engineering equipment, especially for small-scale processes that require fast implementation in industry to obtain small quantities of the product, are shown. Particular examples of successful use of microchannel reactors for various types of organic synthesis are given, primary attention being devoted to the design features of microchannel reactors. The bibliography includes 118 references.

  1. Ascorbate synthesis in fishes: A review.

    PubMed

    Ching, Biyun; Chew, Shit F; Ip, Yuen K

    2015-02-01

    Biosynthesis of ascorbate is known to occur in liver and/or kidney of some vertebrates; however, a recent study discovered the expression of l-gulono-γ-lactone oxidase, an enzyme essential for ascorbate synthesis, in the brain of the African lungfish, Protopterus annectens. This report provides an up-to-date review on ascorbate synthesis in fishes and the possible future directions of study in view of the discovery of the unusual site of ascorbate biosynthesis.

  2. ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS

    SciTech Connect

    Unknown

    1999-04-01

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  3. Alternative fuels and chemicals from synthesis gas

    SciTech Connect

    Unknown

    1998-08-01

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  4. Process for producing synthesis gas from wood

    SciTech Connect

    Curran, G.P.; Lancet, M.S.

    1982-06-15

    In a process for producing synthesis gas by reacting a solid carbonaceous fuel with water in the presence of a carbon dioxide acceptor to produce a synthesis gas rich in hydrogen with at least a portion of the carbon dioxide so produced being reacted with the carbon dioxide acceptor to produce calcium carbonate and to provide sufficient heat to maintain a desired reaction temperature, an improvement comprising; the use of finely-divided wood as the solid carbonaceous fuel.

  5. Alternative Fuels and Chemicals from Synthesis Gas

    SciTech Connect

    Peter Tijrn

    2003-01-02

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  6. Nickel-Catalyzed Synthesis of Quinazolinediones.

    PubMed

    Beutner, Gregory L; Hsiao, Yi; Razler, Thomas; Simmons, Eric M; Wertjes, William

    2017-03-03

    A nickel(0)-catalyzed method for the synthesis of quinazolinediones from isatoic anhydrides and isocyanates is described. High-throughput ligand screening revealed that XANTPHOS was the optimal ligand for this transformation. Subsequent optimization studies, supported by kinetic analysis, significantly expanded the reaction scope. The reaction exhibits a case of substrate inhibition kinetics with respect to the isocyanate. Preliminary results on an asymmetric synthesis of atropisomeric quinazolinediones are reported.

  7. Organic Synthesis and Catalysis in Microemulsions

    DTIC Science & Technology

    1988-02-02

    RECIPIENT’S CATALOG NUM •ER A ~ ~ I &j-/( N/A N/A 4. TITLE €,,,1 &"#I*) S. TYPE OF REPORT & PERiO4 COVERED LAJ Organic Synthesis and Catalysis in...ey Dstq "Av: ’ijj,,i d i o I l UNCLASSIFIED SECURITY CLASSIFICATION Of THIS PAGEg’lrhn Date Entered) Organic Synthesis and Catalysis in

  8. Synthesis of Cubane Based Energetic Molecules

    DTIC Science & Technology

    1993-04-13

    cubanes. We developed several new routes for the synthesis of the dinitramino group , (N(NO2)2). Our work on the preparation of the dinitamide group led... groups creates exceptionally dense and powerful explosives, propellants, and fuels. The cubane system is geometrically very different from ordinary...routes for the synthesis of the dinitramino group , N(NO2)2 in other investigations related to this program. This work resulted in new, more efficient

  9. Fluorous Mixture Synthesis of Asymmetric Dendrimers

    PubMed Central

    Jiang, Zhong-Xing; Yu, Yihua Bruce

    2010-01-01

    A divergent fluorous mixture synthesis (FMS) of asymmetric fluorinated dendrimers has been developed. Four generations of fluorinated dendrimers with the same fluorinated moiety were prepared with high efficiency, yield and purity. Comparison of the physicochemical properties of these dendrimers provided valuable information for their application and future optimization. This strategy has not only provided a practical method for the synthesis and purification of dendrimers, but also established the possibility of utilizing the same fluorinated moiety for FMS. PMID:20170088

  10. Synthesis and Characterization of New Phosphazene Polymers.

    DTIC Science & Technology

    1988-01-21

    reaction of a poly( alkyl /arylphosphazene). In this study, one-half of the methyl groups in [Ph(Me)PN]n (chosen for its solubility in THF as opposed to...polymerization reaction ; and (5) the derivative chemistry of the preformed poly( alkyl /arylphosphazenes)., Synthesis of Poly( alkyl /arylphosphazenes) SC A... vessels , these phosphoranimines quantitatively eliminate the silyl ether byproduct, Me3SiOCH2CF 3 , to form the poly( alkyl /arylphosphazenes). The synthesis

  11. Attachment Stimulates Exopolysaccharide Synthesis by a Bacterium

    SciTech Connect

    Vandevivere, P.; Kirchman, D. L.

    1993-07-28

    Addition of sand to shake-flask cultures seemed to induce exopolymer synthesis by a number of subsurface bacterial isolates, as revealed by optical microscopy. Several additional lines of evidence indicate that exopolymer production by attached cells (in continuous-flow, sand-packed columns) was greater than by their free-living counterparts. The mechanism by which attachment stimulated exopolymer synthesis did not involve changes of the specific growth rate, growth stage, or limiting nutrient.

  12. Some New Methods of Music Synthesis.

    DTIC Science & Technology

    1980-08-01

    AD-AO90 130 MASSACHUSETTS INST OF TECH CAMBRIDGE LAB FOR COMPUTE-ETC F/6 9/2 OME ME NW METHODS OF MUSIC SYNTHESIS. (U) AUG 80 W & PASEMAN...METHODS OF MUSIC SYNHEIS William Gerhard Paseman ~- August 1980 This research was supported by the Advanced Research Projects Agency of the Department of...black number) Artif icial Intelligence Msic Ccirposition Real Time Music Synthesis 20 ABSTRACT (Continue on reverse stde it necessary and identity by

  13. ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS

    SciTech Connect

    Unknown

    1999-01-01

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  14. ALTERNATIVE FUELS AND CHEMICALS FROM SYNTHESIS GAS

    SciTech Connect

    Unknown

    1998-01-01

    The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.

  15. Toward more "ideal" polyketide natural product synthesis: a step-economical synthesis of zincophorin methyl ester.

    PubMed

    Harrison, Tyler J; Ho, Stephen; Leighton, James L

    2011-05-18

    A highly efficient and step-economical synthesis of zincophorin methyl ester has been achieved. The unprecedented step economy of this zincophorin synthesis is principally due to an application of the tandem silylformylation-crotylsilylation/Tamao oxidation-diastereoselective tautomerization reaction, which achieves in a single step what would typically require a significant multistep sequence.

  16. Biocatalyzed Regioselective Synthesis in Undergraduate Organic Laboratories: Multistep Synthesis of 2-Arachidonoylglycerol

    ERIC Educational Resources Information Center

    Johnston, Meghan R.; Makriyannis, Alexandros; Whitten, Kyle M.; Drew, Olivia C.; Best, Fiona A.

    2016-01-01

    In order to introduce the concepts of biocatalysis and its utility in synthesis to organic chemistry students, a multistep synthesis of endogenous cannabinergic ligand 2-arachidonoylglycerol (2-AG) was tailored for use as a laboratory exercise. Over four weeks, students successfully produced 2-AG, purifying and characterizing products at each…

  17. Synthesis and crystal structure of ((E)-{2-[(E)-(4-hy­droxynaphthalen-1-yl)methyl­idene]hydrazin-1-yl}(methyl­sulfan­yl)methyl­idene)azanium hydrogen sulfate monohydrate

    PubMed Central

    Nehar, Oussama; Louhibi, Samira; Boukli-Hacene, Leila; Roisnel, Thierry

    2016-01-01

    In the title hydrated mol­ecular salt, C13H14N3S+·HSO4 −·H2O, the protonation of the azomethine N atom in sulfuric acid medium involves the formation of the bis­ulfate anion. The mol­ecular structure of the cation is obtained from the thiol tautomer of thio­semicarbazone wherein the naphthalene moiety and the conjugation of the bonds contribute to the planarity of the mol­ecular skeleton. In the crystal, the cation, anion and water mol­ecule of crystallization are linked by a series of O—H⋯O and N—H⋯O hydrogen bonds, forming a three-dimensional network. Within this network, there are also C—H⋯π inter­actions present involving symmetry-related naphthalene rings. PMID:27920927

  18. Synthesis and crystal structure of ((E)-{2-[(E)-(4-hy-droxynaphthalen-1-yl)methyl-idene]hydrazin-1-yl}(methyl-sulfan-yl)methyl-idene)azanium hydrogen sulfate monohydrate.

    PubMed

    Nehar, Oussama; Louhibi, Samira; Boukli-Hacene, Leila; Roisnel, Thierry

    2016-09-01

    In the title hydrated mol-ecular salt, C13H14N3S(+)·HSO4(-)·H2O, the protonation of the azomethine N atom in sulfuric acid medium involves the formation of the bis-ulfate anion. The mol-ecular structure of the cation is obtained from the thiol tautomer of thio-semicarbazone wherein the naphthalene moiety and the conjugation of the bonds contribute to the planarity of the mol-ecular skeleton. In the crystal, the cation, anion and water mol-ecule of crystallization are linked by a series of O-H⋯O and N-H⋯O hydrogen bonds, forming a three-dimensional network. Within this network, there are also C-H⋯π inter-actions present involving symmetry-related naphthalene rings.

  19. Recent Advances in the Synthesis of 2-Pyrones

    PubMed Central

    Lee, Jong Seok

    2015-01-01

    The present review summarizes the recent progresses in the synthesis of 2-pyrones and the application to the synthesis of marine natural products. Especially, much attention was placed on the transition metal catalyzed synthetic methodologies in this review. PMID:25806468

  20. Efficient synthesis of benzamide riboside, a potential anticancer agent.

    PubMed

    Bonnac, Laurent F; Gao, Guang-Yao; Chen, Liqiang; Patterson, Steven E; Jayaram, Hiremagalur N; Pankiewicz, Krzysztof W

    2007-01-01

    An efficient five step synthesis of benzamide riboside (BR) amenable for a large scale synthesis has been developed. It allows for extensive pre-clinical studies of BR as a potential anticancer agent.

  1. Sustainable Alternatives for the Synthesis of Organics and Nanomaterials

    EPA Science Inventory

    The presentation summarizes recent activity in eco-friendly chemical synthesis, which involves benign alternatives, such as the use of supported reagents, and greener reaction medium in aqueous or solvent-free conditions. The synthesis of heterocyclic compounds, coupling reaction...

  2. Sustainable Strategies for the Synthesis of Organics and Nanomaterials

    EPA Science Inventory

    The presentation summarizes recent activity in eco-friendly chemical synthesis, which involves benign alternatives, such as the use of supported reagents, and greener reaction medium in aqueous or solvent-free conditions. The synthesis of heterocyclic compounds, coupling reaction...

  3. Sustainable synthesis of monodispersed spinel nano-ferrites

    EPA Science Inventory

    A sustainable approach for the synthesis of various monodispersed spinel ferrite nanoparticles has been developed that occurs at water-toluene interface under both conventional and microwave hydrothermal conditions. This general synthesis procedure utilizes readily available and ...

  4. Template synthesis of nanophase mesocarbon.

    PubMed

    Yang, Nancy Y; Jian, Kengqing; Külaots, Indrek; Crawford, Gregory P; Hurt, Robert H

    2003-10-01

    Templating techniques are used increasingly to create carbon materials with precisely engineered pore systems. This article presents a new templating technique that achieves simultaneous control of pore structure and molecular (crystal) structure in a single synthesis step. With the use of discotic liquid crystalline precursors, unique carbon structures can be engineered by selecting the size and geometry of the confining spaces and selecting the template material to induce edge-on or face-on orientation of the discotic precursor. Here mesophase pitch is infiltrated by capillary forces into a nanoporous glass followed by slow carbonization and NaOH etching. The resulting porous carbon material exhibits interconnected solid grains about 100 nm in size, a monodisperse pore size of 60 nm, 42% total porosity, and an abundance of edge-plane inner surfaces that reflect the favored edge-on anchoring of the mesophase precursor on glass. This new carbon form is potentially interesting for a number of important applications in which uniform large pores, active-site-rich surfaces, and easy access to interlayer spaces in nanometric grains are advantageous.

  5. ''The control of lignin synthesis''

    SciTech Connect

    Carlson, John E.

    2005-04-07

    In this project we tested the hypothesis that regulation of the synthesis of lignin in secondary xylem cells in conifer trees involves the transport of glucosylated lignin monomers to the wall of xylem cells, followed by de-glucosylation in the cell wall by monolignol-specific glucosidase enzymes, which activates the monomers for lignin polymerization. The information we gathered is relevant to the fundamental understanding of how trees make wood, and to the applied goal of more environmentally friendly pulp and paper production. We characterized the complete genomic structure of the Coniferin-specific Beta-glucosidase (CBG) gene family in the conifers loblolly pine (Pinus taeda) and lodgepole pine (Pinus contorta), and partial genomic sequences were obtained in several other tree species. Both pine species contain multiple CBG genes which raises the possibility of differential regulation, perhaps related to the multiple roles of lignin in development and defense. Subsequent projects will need to include detailed gene expression studies of each gene family member during tree growth and development, and testing the role of each monolignol-specific glucosidase gene in controlling lignin content.

  6. Automatic Synthesis Imaging with Difmap

    NASA Astrophysics Data System (ADS)

    Pearson, T. J.; Shepherd, M. C.; Taylor, G. B.; Myers, S. T.

    1994-12-01

    Difmap is a new interactive program for synthesis imaging. It includes data display, data editing, self-calibration, imaging, deconvolution, and model-fitting. The program can handle continuum, spectral-line, and polarization data from connected-element and very-long-baseline interferometer arrays. The program is written in ANSI C and runs on UNIX workstations. We describe the operation of the program with example data sets from the Very Large Array, the global VLBI network, and the Owens Valley Millimeter Array. We have developed Difmap scripts for automatic mapping and self-calibration of both VLA and VLBI data. We describe the strategies adopted for choosing the imaging, deconvolution, and self-calibration parameters, and show how these automatic scripts have made possible the rapid imaging of several hundred sources in the Caltech--Jodrell Bank VLBI surveys (CJ1 and CJ2) and several thousand sources in a VLA search for gravitational lenses (CLASS). Other images made with automatic mapping in Difmap are presented at this meeting by Fassnacht et al., Myers et al., and Taylor et al.

  7. Dextran Nanoparticle Synthesis and Properties

    PubMed Central

    Wasiak, Iga; Kulikowska, Aleksandra; Janczewska, Magdalena; Michalak, Magdalena; Cymerman, Iwona A.; Nagalski, Andrzej; Kallinger, Peter; Szymanski, Wladyslaw W.; Ciach, Tomasz

    2016-01-01

    Dextran is widely exploited in medical products and as a component of drug-delivering nanoparticles (NPs). Here, we tested whether dextran can serve as the main substrate of NPs and form a stable backbone. We tested dextrans with several molecular masses under several synthesis conditions to optimize NP stability. The analysis of the obtained nanoparticles showed that dextran NPs that were synthesized from 70 kDa dextran with a 5% degree of oxidation of the polysaccharide chain and 50% substitution with dodecylamine formed a NP backbone composed of modified dextran subunits, the mean diameter of which in an aqueous environment was around 100 nm. Dextran NPs could be stored in a dry state and reassembled in water. Moreover, we found that different chemical moieties (e.g., drugs such as doxorubicin) can be attached to the dextran NPs via a pH-dependent bond that allows release of the drug with lowering pH. We conclude that dextran NPs are a promising nano drug carrier. PMID:26752182

  8. The Chemical Synthesis of Discodermolide

    NASA Astrophysics Data System (ADS)

    Paterson, I.; Florence, G. J.

    The marine sponge-derived polyketide discodermolide is a potent antimitotic agent that represents a promising natural product lead structure in the treatment of cancer. Discodermolide shares the same microtubule-stabilising mechanism of action as Taxol®, inhibits the growth of solid tumours in animal models and shows synergy with Taxol. The pronounced cytotoxicity of discodermolide, which is maintained against cancer cell lines that display resistance to Taxol and other drugs, combined with its scarce availability from its natural source, has fuelled significant academic and industrial interest in devising a practical total synthesis as a means of ensuring a sustainable supply for drug development. This chapter surveys the various total syntheses of discodermolide that have been completed over the period 1993-2007, focusing on the strategies employed for introduction of the multiple stereocentres and achieving control over the alkene geometry, along with the various methods used for realising the pivotal fragment couplings to assemble progressively the full carbon skeleton. This dedicated synthetic effort has triumphed in removing the supply problem for discodermolide, providing sufficient material for extensive biological studies and enabling its early stage clinical development, as well as facilitating SAR studies for lead optimisation.

  9. Asymmetric Synthesis (by Garry Procter)

    NASA Astrophysics Data System (ADS)

    Kesler, Brenda

    1998-05-01

    Oxford University Press: New York, 1996. vi + 237 pp. ISBN 0 19 855726 4 (cloth); 85.00. ISBN 0 19 855725 6 (paper); 37.00. This ever-expanding area of organic chemistry is indeed a daunting challenge for a book, both in terms of the breadth of material and the rapid change of events relative to the publishing time line. I feel the author has done an admirable job juggling these two issues. Following an introductory chapter on the principles of asymmetric induction are seven chapters on individual classes of reactions: additions to carbonyl compounds, alpha-substitution using chiral enolates, asymmetric aldol reactions, additions to C-C double bonds, reduction and oxidation, rearrangements, and hydrolysis and esterification. The vast majority of the references are from the mid-80s through the early 90s, including both general and seminal references. In particular, I feel a very solid balance has been achieved between content and clarity. The chapter on "Principles" at the beginning was very well thought out and organized and is a wonderful overview of asymmetric synthesis. This is balanced nicely in subsequent chapters on specific methods where very useful, practical generalizations are presented, such as the "best alpha-hydroxylation" method or the "best alpha-bromination" procedure. The chapters also have nicely integrated examples that show the power of the particular bond construction being examined as it applies to published total syntheses, my favorite being the ones in the chapter on asymmetric aldol reactions.

  10. Velocimetry signal synthesis with fringen.

    SciTech Connect

    Dolan, Daniel H., III

    2011-02-01

    An important part of velocimetry analysis is the recovery of a known velocity history from simulated data signals. The fringen program synthesizes VISAR and PDV signals, given a specified velocity history, using exact formulations for the optical signal. Time-dependent light conditions, non-ideal measurement conditions, and various diagnostic limitations (noise, etc.) may be incorporated into the simulated signals. This report describes the fringen program, which performs forward VISAR (Velocity Interferometer System for Any Reflector) and PDV (Photonic Doppler Velocimetry, also known as heterodyne velocimetry) analysis. Nearly all effects that might occur in VISAR/PDV measurement of a single velocity can be modeled by fringen. The program operates in MATLAB, either within a graphical interface or as a user-callable function. The current stable version of fringen is 0.3, which was released in October 2010. The following sections describe the operation and use of fringen. Section 2 gives a brief overview of VISAR and PDV synthesis. Section 3 illustrates the graphical and console interface of fringen. Section 4 presents several example uses of the program. Section 5 summarizes program capabilities and discusses potential future work.

  11. Enzymatic Synthesis of Magnetic Nanoparticles

    PubMed Central

    Kolhatkar, Arati G.; Dannongoda, Chamath; Kourentzi, Katerina; Jamison, Andrew C.; Nekrashevich, Ivan; Kar, Archana; Cacao, Eliedonna; Strych, Ulrich; Rusakova, Irene; Martirosyan, Karen S.; Litvinov, Dmitri; Lee, T. Randall; Willson, Richard C.

    2015-01-01

    We report the first in vitro enzymatic synthesis of paramagnetic and antiferromagnetic nanoparticles toward magnetic ELISA reporting. With our procedure, alkaline phosphatase catalyzes the dephosphorylation of l-ascorbic-2-phosphate, which then serves as a reducing agent for salts of iron, gadolinium, and holmium, forming magnetic precipitates of Fe45±14Gd5±2O50±15 and Fe42±4Ho6±4O52±5. The nanoparticles were found to be paramagnetic at 300 K and antiferromagnetic under 25 K. Although weakly magnetic at 300 K, the room-temperature magnetization of the nanoparticles found here is considerably greater than that of analogous chemically-synthesized LnxFeyOz (Ln = Gd, Ho) samples reported previously. At 5 K, the nanoparticles showed a significantly higher saturation magnetization of 45 and 30 emu/g for Fe45±14Gd5±2O50±15 and Fe42±4Ho6±4O52±5, respectively. Our approach of enzymatically synthesizing magnetic labels reduces the cost and avoids diffusional mass-transfer limitations associated with pre-synthesized magnetic reporter particles, while retaining the advantages of magnetic sensing. PMID:25854425

  12. Impaired glutathione synthesis in neurodegeneration.

    PubMed

    Aoyama, Koji; Nakaki, Toshio

    2013-10-18

    Glutathione (GSH) was discovered in yeast cells in 1888. Studies of GSH in mammalian cells before the 1980s focused exclusively on its function for the detoxication of xenobiotics or for drug metabolism in the liver, in which GSH is present at its highest concentration in the body. Increasing evidence has demonstrated other important roles of GSH in the brain, not only for the detoxication of xenobiotics but also for antioxidant defense and the regulation of intracellular redox homeostasis. GSH also regulates cell signaling, protein function, gene expression, and cell differentiation/proliferation in the brain. Clinically, inborn errors in GSH-related enzymes are very rare, but disorders of GSH metabolism are common in major neurodegenerative diseases showing GSH depletion and increased levels of oxidative stress in the brain. GSH depletion would precipitate oxidative damage in the brain, leading to neurodegenerative diseases. This review focuses on the significance of GSH function, the synthesis of GSH and its metabolism, and clinical disorders of GSH metabolism. A potential approach to increase brain GSH levels against neurodegeneration is also discussed.

  13. Impaired Glutathione Synthesis in Neurodegeneration

    PubMed Central

    Aoyama, Koji; Nakaki, Toshio

    2013-01-01

    Glutathione (GSH) was discovered in yeast cells in 1888. Studies of GSH in mammalian cells before the 1980s focused exclusively on its function for the detoxication of xenobiotics or for drug metabolism in the liver, in which GSH is present at its highest concentration in the body. Increasing evidence has demonstrated other important roles of GSH in the brain, not only for the detoxication of xenobiotics but also for antioxidant defense and the regulation of intracellular redox homeostasis. GSH also regulates cell signaling, protein function, gene expression, and cell differentiation/proliferation in the brain. Clinically, inborn errors in GSH-related enzymes are very rare, but disorders of GSH metabolism are common in major neurodegenerative diseases showing GSH depletion and increased levels of oxidative stress in the brain. GSH depletion would precipitate oxidative damage in the brain, leading to neurodegenerative diseases. This review focuses on the significance of GSH function, the synthesis of GSH and its metabolism, and clinical disorders of GSH metabolism. A potential approach to increase brain GSH levels against neurodegeneration is also discussed. PMID:24145751

  14. Molybdenum compounds in organic synthesis

    NASA Astrophysics Data System (ADS)

    Khusnutdinov, R. I.; Oshnyakova, T. M.; Dzhemilev, U. M.

    2017-02-01

    The review presents the first analysis and systematic discussion of data published in the last 35–40 years on the use of molybdenum compounds and complexes in organic synthesis and catalysis of various ion coordination and radical reactions. Detailed account is given of the key trends in the use of molybdenum complexes as catalysts of alkene epoxidation and oxyketonation, oxidation of sulfur, nitrogen and phosphorus compounds, hydrosilylation of 1,3-dienes, ketones and aldehydes, hydrostannylation of acetylenes and hydrogermylation of norbornadienes. Considerable attention is paid to the description of new reactions and in situ generation of highly reactive hypohalites, ROX and HOX, induced by molybdenum complexes and the use of hypohalites in oxidative transformations. Data on the application of molybdenum complexes in well-known reactions are discussed, including Kharasch and Pauson–Khand reactions, allylic alkylation of C-nucleophiles, aminocarbonylation of halo derivatives and oligomerization of cyclic dienes, trienes, alkynes and 1,3-dienes. The last Section of the review considers 'unusual' organic reactions involving molybdenum compounds and complexes. The bibliography includes 257 references.

  15. General methods for iminosugar synthesis.

    PubMed

    Cipolla, Laura; la Ferla, Barbara; Nicotra, Francesco

    2003-01-01

    Recent iminosugar syntheses starting both from commercially available sugars and non-glycidic precursors, are reported in this article. Exploiting carbohydrate starting materials, different synthetic approaches are described, mainly based on the introduction of an amino function in the sugar skeleton and the subsequent aminocyclization in order to generate the piperidine or pyrrolidine ring. The aminocyclization has been performed in different ways: reductive amination of azidoketones, intramolecular amino group attack on leaving groups and activated double bonds. In some cases one-pot amination and cyclization have been performed using ammonia or a primary amine and a di-functionalised sugar. Bicyclic compounds have also been obtained through these procedures. Starting from non-carbohydrate precursors, the nitrogen containing cycle, already present or easily obtained by Diels-Alder reactions, has been variously functionalised and stereo-differentiated by asymmetric induction or by resolution of the racemate. The syntheses of a variety of innovative structures, such as 1-N-iminosugars, iminosugars with two nitrogen atoms in the ring, iminosugars incorporating a guanidine function, imidazole-, triazole- and tetrazole-fused iminosugars, sugar-like aza-, oxa-, and thio-indolizidines, are reported. Finally the synthesis of glycoconjugate-related iminosugars, where the "pseudoanomeric" centre is linked to amino acid or peptide residues, and iminosugar phosphonates and nucleosides have been reviewed.

  16. Combinatorial synthesis of novel materials

    DOEpatents

    Schultz, Peter G.; Xiang, Xiaodong; Goldwasser, Isy

    2002-02-12

    Methods and apparatus for the preparation and use of a substrate having an array of diverse materials in predefined regions thereon. A substrate having an array of diverse materials thereon is generally prepared by delivering components of materials to predefined regions on a substrate, and simultaneously reacting the components to form at least two materials. Materials which can be prepared using the methods and apparatus of the present invention include, for example, covalent network solids, ionic solids and molecular solids. More particularly, materials which can be prepared using the methods and apparatus of the present invention include, for example, inorganic materials, intermetallic materials, metal alloys, ceramic materials, organic materials, organometallic materials, non-biological organic polymers, composite materials (e.g., inorganic composites, organic composites, or combinations thereof), etc. Once prepared, these materials can be screened for useful properties including, for example, electrical, thermal, mechanical, morphological, optical, magnetic, chemical, or other properties. Thus, the present invention provides methods for the parallel synthesis and analysis of novel materials having useful properties.

  17. Combinatorial synthesis of novel materials

    DOEpatents

    Schultz, Peter G.; Xiang, Xiaodong; Goldwasser, Isy

    1999-01-01

    Methods and apparatus for the preparation and use of a substrate having an array of diverse materials in predefined regions thereon. A substrate having an array of diverse materials thereon is generally prepared by delivering components of materials to predefined regions on a substrate, and simultaneously reacting the components to form at least two materials. Materials which can be prepared using the methods and apparatus of the present invention include, for example, covalent network solids, ionic solids and molecular solids. More particularly, materials which can be prepared using the methods and apparatus of the present invention include, for example, inorganic materials, intermetallic materials, metal alloys, ceramic materials, organic materials, organometallic materials, non-biological organic polymers, composite materials (e.g., inorganic composites, organic composites, or combinations thereof), etc. Once prepared, these materials can be screened for useful properties including, for example, electrical, thermal, mechanical, morphological, optical, magnetic, chemical, or other properties. Thus, the present invention provides methods for the parallel synthesis and analysis of novel materials having useful properties.

  18. Combinatorial synthesis of novel materials

    DOEpatents

    Schultz, Peter G.; Xiang, Xiaodong; Goldwasser, Isy

    1999-12-21

    Methods and apparatus for the preparation and use of a substrate having an array of diverse materials in predefined regions thereon. A substrate having an array of diverse materials thereon is generally prepared by delivering components of materials to predefined regions on a substrate, and simultaneously reacting the components to form at least two materials. Materials which can be prepared using the methods and apparatus of the present invention include, for example, covalent network solids, ionic solids and molecular solids. More particularly, materials which can be prepared using the methods and apparatus of the present invention include, for example, inorganic materials, intermetallic materials, metal alloys, ceramic materials, organic materials, organometallic materials, non-biological organic polymers, composite materials (e.g., inorganic composites, organic composites, or combinations thereof), etc. Once prepared, these materials can be screened for useful properties including, for example, electrical, thermal, mechanical, morphological, optical, magnetic, chemical, or other properties. Thus, the present invention provides methods for the parallel synthesis and analysis of novel materials having useful properties.

  19. Combinatorial synthesis of novel materials

    DOEpatents

    Schultz, Peter G.; Xiang, Xiaodong; Goldwasser, Isy

    2001-01-01

    Methods and apparatus for the preparation and use of a substrate having an array of diverse materials in predefined regions thereon. A substrate having an array of diverse materials thereon is generally prepared by delivering components of materials to predefined regions on a substrate, and simultaneously reacting the components to form at least two materials. Materials which can be prepared using the methods and apparatus of the present invention include, for example, covalent network solids, ionic solids and molecular solids. More particularly, materials which can be prepared using the methods and apparatus of the present invention include, for example, inorganic materials, intermetallic materials, metal alloys, ceramic materials, organic materials, organometallic materials, non-biological organic polymers, composite materials (e.g., inorganic composites, organic composites, or combinations thereof), etc. Once prepared, these materials can be screened for useful properties including, for example, electrical, thermal, mechanical, morphological, optical, magnetic, chemical, or other properties. Thus, the present invention provides methods for the parallel synthesis and analysis of novel materials having useful properties.

  20. Antibiotics that target protein synthesis.

    PubMed

    McCoy, Lisa S; Xie, Yun; Tor, Yitzhak

    2011-01-01

    The key role of the bacterial ribosome makes it an important target for antibacterial agents. Indeed, a large number of clinically useful antibiotics target this complex translational ribonucleoprotein machinery. The majority of these compounds, mostly of natural origin, bind to one of the three key ribosomal sites: the decoding (or A-site) on the 30S, the peptidyl transferase center (PTC) on the 50S, and the peptide exit tunnel on the 50S. Antibiotics that bind the A-site, such as the aminoglycosides, interfere with codon recognition and translocation. Peptide bond formation is inhibited when small molecules like oxazolidinones bind at the PTC. Finally, macrolides tend to block the growth of the amino acid chain at the peptide exit tunnel. In this article, the major classes of antibiotics that target the bacterial ribosome are discussed and classified according to their respective target. Notably, most antibiotics solely interact with the RNA components of the bacterial ribosome. The surge seen in the appearance of resistant bacteria has not been met by a parallel development of effective and broad-spectrum new antibiotics, as evident by the introduction of only two novel classes of antibiotics, the oxazolidinones and lipopeptides, in the past decades. Nevertheless, this significant health threat has revitalized the search for new antibacterial agents and novel targets. High resolution structural data of many ribosome-bound antibiotics provide unprecedented insight into their molecular contacts and mode of action and inspire the design and synthesis of new candidate drugs that target this fascinating molecular machine.

  1. Asymmetric catalysis in organic synthesis

    SciTech Connect

    Reilly, S.D.; Click, D.R.; Grumbine, S.K.; Scott, B.L.; Watkins, J.G.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The goal of the project was to prepare new catalyst systems, which would perform chemical reactions in an enantioselective manner so as to produce only one of the possible optical isomers of the product molecule. The authors have investigated the use of lanthanide metals bearing both diolate and Schiff-base ligands as catalysts for the enantioselective reduction of prochiral ketones to secondary alcohols. The ligands were prepared from cheap, readily available starting materials, and their synthesis was performed in a ''modular'' manner such that tailoring of specific groups within the ligand could be carried out without repeating the entire synthetic procedure. In addition, they have developed a new ligand system for Group IV and lanthanide-based olefin polymerization catalysts. The ligand system is easily prepared from readily available starting materials and offers the opportunity to rapidly prepare a wide range of closely related ligands that differ only in their substitution patterns at an aromatic ring. When attached to a metal center, the ligand system has the potential to carry out polymerization reactions in a stereocontrolled manner.

  2. Intestinal apolipoprotein synthesis in the newborn piglet.

    PubMed

    Black, D D; Rohwer-Nutter, P L

    1991-01-01

    To determine the effects of dietary and biliary lipid absorption on intestinal apo B-48 and apo A-I synthesis in the newborn piglet, 2-d-old female piglets were prepared with a duodenal infusion catheter. After recovery, animals were given either low triglyceride (Vivonex; VIV group) or high triglyceride (Intralipid; FAT group) diets by continuous intraduodenal infusion for 24 h. A bile-diverted group was also studied. Segments of proximal jejunum and distal ileum were then pulse-radiolabeled in vivo with 3H-leucine. Mucosal apo B-48 and apo A-I were immunoprecipitated, and apoprotein synthesis was expressed as percentage of total protein synthesis. Mucosal apoprotein content (ng apoprotein/microgram total protein) was measured by competitive ELISA assays. In jejunum and ileum, apo B-48 synthesis was not different in the three groups. However, apo B content increased 2.4-fold in jejunum and 1.7-fold in ileum in the FAT group compared with the VIV group. Immunoblotting revealed the majority of jejunal apo B to be apo B-48, not apo B-100 from contaminating plasma lipoproteins, in all three experimental groups. Bile-diverted animals had decreased jejunal apo B content compared with the VIV group. Jejunal apo A-I synthesis and content were approximately 2-fold higher in FAT animals compared with the VIV group. Although ileal apo A-I synthesis was also 2-fold higher in the FAT group, apo A-I content was not different from the VIV group. Neither jejunal nor ileal apo A-I synthesis was significantly affected by bile diversion, even though jejunal apo A-I content was decreased by over two thirds compared with the VIV animals. In the newborn piglet, intestinal synthesis of apo B-48 and apo A-I is differentially regulated by luminal lipid absorption. Although fat feeding and bile diversion regulate mucosal apo B-48 content, synthesis is unchanged, indicating a posttranslational regulatory mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. High octane ethers from synthesis gas-derived alcohols

    SciTech Connect

    Klier, K.; Herman, R.G.; Johansson, M.; Feeley, O.C.

    1992-01-01

    The objective of the proposed research is to synthesize high octane ethers, primarily methyl isobutyl ether (MIBE) and methyl tertiary butyl ether (MTBE), directly from H{sub 2}/CO/CO{sub 2} coal-derived synthesis gas via alcohol mixtures that are rich in methanol and 2-methyl-1-propanol (isobutanol). The overall scheme involves gasification of coal, purification and shifting of the synthesis gas, higher alcohol synthesis, and direct synthesis of ethers.

  4. Microwaves and nanoparticles: from synthesis to imaging

    NASA Astrophysics Data System (ADS)

    Meissner, Kenith E.; Majithiaa, Ravish; Brown, R. A.; Wang, Lihong V.; Maffeis, T. G. G.

    2011-03-01

    We investigate the use of energy delivery using microwave radiation for both synthesis of nanoparticles as well as a hybrid imaging technique known as thermoacoustic tomography (TAT). In each instance, the absorption of microwave radiation is converted into heat. In the case of nanoparticle synthesis, water is used as the solvent and heated to induce synthesis of the nanostructures. For this aqueous synthesis technique, we demonstrate the use of both pulsed and continuous wave (CW) microwave systems operating at 2.45 GHz. In this report, we concentrate on ZnO nanostructures including nanorods, nanowire arrays and nanobelts. These are compared with nanowire arrays and nanobelts grown by vapor transport through both electron microscopy and photo-excited luminescence. We also review the use of iron oxide (Fe3O4) nanoparticles as contrast agents in TAT as previously reported. Here, we measured the properties of the colloidal nanoparticles in the microwave regime and compared the absorption with the TAT signal produced by our thermoacoustic imaging system at 3 GHz. The nanoparticles directly absorb the microwave radiation and produce a thermo-acoustic signal. The results from nanoparticles are compared to the signal produced by deionized water. The results demonstrate that microwaves represent an efficient method for the delivery of energy for both synthesis and biomedical imaging.

  5. Synthesis of Morphinan Alkaloids in Saccharomyces cerevisiae.

    PubMed

    Fossati, Elena; Narcross, Lauren; Ekins, Andrew; Falgueyret, Jean-Pierre; Martin, Vincent J J

    2015-01-01

    Morphinan alkaloids are the most powerful narcotic analgesics currently used to treat moderate to severe and chronic pain. The feasibility of morphinan synthesis in recombinant Saccharomyces cerevisiae starting from the precursor (R,S)-norlaudanosoline was investigated. Chiral analysis of the reticuline produced by the expression of opium poppy methyltransferases showed strict enantioselectivity for (S)-reticuline starting from (R,S)-norlaudanosoline. In addition, the P. somniferum enzymes salutaridine synthase (PsSAS), salutaridine reductase (PsSAR) and salutaridinol acetyltransferase (PsSAT) were functionally co-expressed in S. cerevisiae and optimization of the pH conditions allowed for productive spontaneous rearrangement of salutaridinol-7-O-acetate and synthesis of thebaine from (R)-reticuline. Finally, we reconstituted a 7-gene pathway for the production of codeine and morphine from (R)-reticuline. Yeast cell feeding assays using (R)-reticuline, salutaridine or codeine as substrates showed that all enzymes were functionally co-expressed in yeast and that activity of salutaridine reductase and codeine-O-demethylase likely limit flux to morphine synthesis. The results of this study describe a significant advance for the synthesis of morphinans in S. cerevisiae and pave the way for their complete synthesis in recombinant microbes.

  6. Automation synthesis from a nonformal specification

    SciTech Connect

    Raikhlin, V.A.

    1995-03-01

    The fundamental possibility of developing universal approaches to the synthesis of finite automata from a nonformal specification requires the introduction of heuristic elements into the synthesis procedure. Various examples of using one of such approaches for the synthesis of asynchronous automata are given elsewhere. The approach on the whole is nondeterministic, which leads to application difficulties. In this paper, we propose a universal technique for the determination of the state set of the automaton being synthesized (synchronous or asynchronous) directly from the initial description. Compared with previous techniques, the heuristic region is smaller and the heuristics is substantively clearer. Further synthesis follows a completely deterministic process. The approach is intended for the design of universal interactive abstract synthesis subsystems. The division of automata into synchronous and asynchronous acquires a special meaning when the initial specification includes an option for choosing a particular type of automaton. If an alternative is available and the reliability requirements are fairly stringent, the asynchronous variant may be preferable. The notion of asynchronous automaton is not linked with the implementation method. The device itself may be synchronous or asynchronous.

  7. Toward the ultimate synthesis/recognition system.

    PubMed

    Furui, S

    1995-10-24

    This paper predicts speech synthesis, speech recognition, and speaker recognition technology for the year 2001, and it describes the most important research problems to be solved in order to arrive at these ultimate synthesis and recognition systems. The problems for speech synthesis include natural and intelligible voice production, prosody control based on meaning, capability of controlling synthesized voice quality and choosing individual speaking style, multilingual and multidialectal synthesis, choice of application-oriented speaking styles, capability of adding emotion, and synthesis from concepts. The problems for speech recognition include robust recognition against speech variations, adaptation/normalization to variations due to environmental conditions and speakers, automatic knowledge acquisition for acoustic and linguistic modeling, spontaneous speech recognition, naturalness and ease of human-machine interaction, and recognition of emotion. The problems for speaker recognition are similar to those for speech recognition. The research topics related to all these techniques include the use of articulatory and perceptual constraints and evaluation methods for measuring the quality of technology and systems.

  8. Synthesis of Morphinan Alkaloids in Saccharomyces cerevisiae

    PubMed Central

    Fossati, Elena; Narcross, Lauren; Ekins, Andrew; Falgueyret, Jean-Pierre; Martin, Vincent J. J.

    2015-01-01

    Morphinan alkaloids are the most powerful narcotic analgesics currently used to treat moderate to severe and chronic pain. The feasibility of morphinan synthesis in recombinant Saccharomyces cerevisiae starting from the precursor (R,S)-norlaudanosoline was investigated. Chiral analysis of the reticuline produced by the expression of opium poppy methyltransferases showed strict enantioselectivity for (S)-reticuline starting from (R,S)-norlaudanosoline. In addition, the P. somniferum enzymes salutaridine synthase (PsSAS), salutaridine reductase (PsSAR) and salutaridinol acetyltransferase (PsSAT) were functionally co-expressed in S. cerevisiae and optimization of the pH conditions allowed for productive spontaneous rearrangement of salutaridinol-7-O-acetate and synthesis of thebaine from (R)-reticuline. Finally, we reconstituted a 7-gene pathway for the production of codeine and morphine from (R)-reticuline. Yeast cell feeding assays using (R)-reticuline, salutaridine or codeine as substrates showed that all enzymes were functionally co-expressed in yeast and that activity of salutaridine reductase and codeine-O-demethylase likely limit flux to morphine synthesis. The results of this study describe a significant advance for the synthesis of morphinans in S. cerevisiae and pave the way for their complete synthesis in recombinant microbes. PMID:25905794

  9. Synthesis of crystalline ceramics for actinide immobilisation

    SciTech Connect

    Burakov, B.; Gribova, V.; Kitsay, A.; Ojovan, M.; Hyatt, N.C.; Stennett, M.C.

    2007-07-01

    Methods for the synthesis of ceramic wasteforms for the immobilization of actinides are common to those for non-radioactive ceramics: hot uniaxial pressing (HUP); hot isostatic pressing (HIP); cold pressing followed by sintering; melting (for some specific ceramics, such as garnet/perovskite composites). Synthesis of ceramics doped with radionuclides is characterized with some important considerations: all the radionuclides should be incorporated into crystalline structure of durable host-phases in the form of solid solutions and no separate phases of radionuclides should be present in the matrix of final ceramic wasteform; all procedures of starting precursor preparation and ceramic synthesis should follow safety requirements of nuclear industry. Synthesis methods that avoid the use of very high temperatures and pressures and are easily accomplished within the environment of a glove-box or hot cell are preferable. Knowledge transfer between the V. G. Khlopin Radium Institute (KRI, Russia) and Immobilisation Science Laboratory (ISL, UK) was facilitated in the framework of a joint project supported by UK Royal Society. In order to introduce methods of precursor preparation and ceramic synthesis we selected well-known procedures readily deployable in radiochemical processing plants. We accounted that training should include main types of ceramic wasteforms which are currently discussed for industrial applications. (authors)

  10. Diversity: School, Family, & Community Connections. Annual Synthesis 2003

    ERIC Educational Resources Information Center

    Boethel, Martha

    2003-01-01

    This research synthesis is the third in a series of reports to help local school, community, and family leaders obtain useful research-based information about key educational issues. This synthesis addresses diversity as it relates to student achievement and school, family, and community connections. This synthesis focuses specifically on three…

  11. Effect of Instruction on ESL Students' Synthesis Writing

    ERIC Educational Resources Information Center

    Zhang, Cui

    2013-01-01

    Synthesis writing has become the focus of much greater attention in the past 10 years in L2 EAP contexts. However, research on L2 synthesis writing has been limited, especially with respect to treatment studies that relate writing instruction to the development of synthesis writing abilities. To address this research gap, the present study…

  12. Fundamentals of the synthesis of automatic machine systems

    NASA Astrophysics Data System (ADS)

    Artobolevskii, I. I.; Ilinskii, D. Ia.

    The theory and methods of the optimization synthesis of automatic manufacturing lines for machine-building, instrument-making, chemical, and other industries are presented. A typical optimization synthesis process, with highly standardized and formalized procedures of structural and parametric synthesis, is examined. The logical and arithmetic problems that are commonly encountered in optimum design are discussed.

  13. Advancements in Research Synthesis Methods: From a Methodologically Inclusive Perspective

    ERIC Educational Resources Information Center

    Suri, Harsh; Clarke, David

    2009-01-01

    The dominant literature on research synthesis methods has positivist and neo-positivist origins. In recent years, the landscape of research synthesis methods has changed rapidly to become inclusive. This article highlights methodologically inclusive advancements in research synthesis methods. Attention is drawn to insights from interpretive,…

  14. N-acetylcysteine stimulates protein synthesis in enterocytes independently of glutathione synthesis.

    PubMed

    Yi, Dan; Hou, Yongqing; Wang, Lei; Long, Minhui; Hu, Shengdi; Mei, Huimin; Yan, Liqiong; Hu, Chien-An Andy; Wu, Guoyao

    2016-02-01

    Dietary supplementation with N-acetylcysteine (NAC) has been reported to improve intestinal health and treat gastrointestinal diseases. However, the underlying mechanisms are not fully understood. According to previous reports, NAC was thought to exert its effect through glutathione synthesis. This study tested the hypothesis that NAC enhances enterocyte growth and protein synthesis independently of cellular glutathione synthesis. Intestinal porcine epithelial cells were cultured for 3 days in Dulbecco's modified Eagle medium containing 0 or 100 μM NAC. To determine a possible role for GSH (the reduced form of glutathione) in mediating the effect of NAC on cell growth and protein synthesis, additional experiments were conducted using culture medium containing 100 μM GSH, 100 μM GSH ethyl ester (GSHee), diethylmaleate (a GSH-depletion agent; 10 μM), or a GSH-synthesis inhibitor (buthionine sulfoximine, BSO; 20 μM). NAC increased cell proliferation, GSH concentration, and protein synthesis, while inhibiting proteolysis. GSHee enhanced cell proliferation and GSH concentration without affecting protein synthesis but inhibited proteolysis. Conversely, BSO or diethylmaleate reduced cell proliferation and GSH concentration without affecting protein synthesis, while promoting protein degradation. At the signaling level, NAC augmented the protein abundance of total mTOR, phosphorylated mTOR, and phosphorylated 70S6 kinase as well as mRNA levels for mTOR and p70S6 kinase in IPEC-1 cells. Collectively, these results indicate that NAC upregulates expression of mTOR signaling proteins to stimulate protein synthesis in enterocytes independently of GSH generation. Our findings provide a hitherto unrecognized biochemical mechanism for beneficial effects of NAC in intestinal cells.

  15. A redox-neutral catechol synthesis.

    PubMed

    Wu, Qian; Yan, Dingyuan; Chen, Ying; Wang, Ting; Xiong, Feng; Wei, Wei; Lu, Yi; Sun, Wei-Yin; Li, Jie Jack; Zhao, Jing

    2017-01-27

    Ubiquitous tyrosinase catalyses the aerobic oxidation of phenols to catechols through the binuclear copper centres. Here, inspired by the Fischer indole synthesis, we report an iridium-catalysed tyrosinase-like approach to catechols, employing an oxyacetamide-directed C-H hydroxylation on phenols. This method achieves one-step, redox-neutral synthesis of catechols with diverse substituent groups under mild conditions. Mechanistic studies confirm that the directing group (DG) oxyacetamide acts as the oxygen source. This strategy has been applied to the synthesis of different important catechols with fluorescent property and bioactivity from the corresponding phenols. Finally, our method also provides a convenient route to (18)O-labelled catechols using (18)O-labelled acetic acid.

  16. A redox-neutral catechol synthesis

    NASA Astrophysics Data System (ADS)

    Wu, Qian; Yan, Dingyuan; Chen, Ying; Wang, Ting; Xiong, Feng; Wei, Wei; Lu, Yi; Sun, Wei-Yin; Li, Jie Jack; Zhao, Jing

    2017-01-01

    Ubiquitous tyrosinase catalyses the aerobic oxidation of phenols to catechols through the binuclear copper centres. Here, inspired by the Fischer indole synthesis, we report an iridium-catalysed tyrosinase-like approach to catechols, employing an oxyacetamide-directed C-H hydroxylation on phenols. This method achieves one-step, redox-neutral synthesis of catechols with diverse substituent groups under mild conditions. Mechanistic studies confirm that the directing group (DG) oxyacetamide acts as the oxygen source. This strategy has been applied to the synthesis of different important catechols with fluorescent property and bioactivity from the corresponding phenols. Finally, our method also provides a convenient route to 18O-labelled catechols using 18O-labelled acetic acid.

  17. Ethylene synthesis and sensitivity in crop plants

    NASA Technical Reports Server (NTRS)

    Klassen, Stephen P.; Bugbee, Bruce

    2004-01-01

    Closed and semi-closed plant growth chambers have long been used in studies of plant and crop physiology. These studies include the measurement of photosynthesis and transpiration via photosynthetic gas exchange. Unfortunately, other gaseous products of plant metabolism can accumulate in these chambers and cause artifacts in the measurements. The most important of these gaseous byproducts is the plant hormone ethylene (C2H4). In spite of hundreds of manuscripts on ethylene, we still have a limited understanding of the synthesis rates throughout the plant life cycle. We also have a poor understanding of the sensitivity of intact, rapidly growing plants to ethylene. We know ethylene synthesis and sensitivity are influenced by both biotic and abiotic stresses, but such whole plant responses have not been accurately quantified. Here we present an overview of basic studies on ethylene synthesis and sensitivity.

  18. Synthesis and processing of nanostructured materials

    SciTech Connect

    Siegel, R.W.

    1992-12-01

    Significant and growing interest is being exhibited in the novel and enhanced properties of nanostructured materials. These materials, with their constituent phase or grain structures modulated on a length scale less than 100 nm, are artificially synthesized by a wide variety of physical, chemical, and mechanical methods. In this NATO Advanced Study Institute, where mechanical behavior is emphasized, nanostructured materials with modulation dimensionalities from one (multilayers) to three (nanophase materials) are mainly considered. No attempt is made in this review to cover in detail all of the diverse methods available for the synthesis of nanostructured materials. Rather, the basic principles involved in their synthesis are discussed in terms of the special properties sought using examples of particular synthesis and processing methodologies. Some examples of the property changes that can result from one of these methods, cluster assembly of nanophase materials, are presented.

  19. Tailor-made synthesis of hydrogels

    SciTech Connect

    Kopecek, J.; Yeh, P.Y.; Kopechkova, P.; Ulbrich, K.

    1993-12-31

    The tailor-made synthesis of hydrogels by crosslinking copolymerization, by crosslinking of polymer precursors, and by polymer-polymer reaction will be analyzed. During the synthesis side-reactions occur resulting in the presence of cycles, unreacted pendant groups, and entanglements in the three dimensional network. The extent of these side-reactions depends on the structure of the crosslinking agent; amount and character of solvent; diffusion control of termination, crosslinking, and eventually propagation; difference in the hydrophilicity of monomer and crosslinking agent, and conversion. Synthesis of biodegradable hydrogels containing degradable sequences in the crosslinks will be used as an example to demonstrate that biorecognition by enzymes depends on the detailed structure of the network.

  20. OPTIMIZING SYNTHESIS GAS YIELD FROM THE CROSS ...

    EPA Pesticide Factsheets

    Symposium Paper Biomass can be gasified to yield synthesis gas, tars, and ash. The process is governed by a number of parameters such as the temperature of the gasifying medium (in this case), and the moisture content of the feedstock. Synthesis gas from gasifying wood pellets was collected and analyzed as a function of inlet air temperature and feedstock moisture content. The air was introduced at temperatures ranging from 630 to 730 °C and the moisture content of the feedstock ranged from 8 to 20%. The data collected was used to establish the relationship between the outcome of gasification and these two parameters, and then to determine optimal operating parameters for maximizing the fuel value (maximizing the concentrations of flammable gases in the synthesis gas) while minimizing the production of gasification tars.

  1. A redox-neutral catechol synthesis

    PubMed Central

    Wu, Qian; Yan, Dingyuan; Chen, Ying; Wang, Ting; Xiong, Feng; Wei, Wei; Lu, Yi; Sun, Wei-Yin; Li, Jie Jack; Zhao, Jing

    2017-01-01

    Ubiquitous tyrosinase catalyses the aerobic oxidation of phenols to catechols through the binuclear copper centres. Here, inspired by the Fischer indole synthesis, we report an iridium-catalysed tyrosinase-like approach to catechols, employing an oxyacetamide-directed C–H hydroxylation on phenols. This method achieves one-step, redox-neutral synthesis of catechols with diverse substituent groups under mild conditions. Mechanistic studies confirm that the directing group (DG) oxyacetamide acts as the oxygen source. This strategy has been applied to the synthesis of different important catechols with fluorescent property and bioactivity from the corresponding phenols. Finally, our method also provides a convenient route to 18O-labelled catechols using 18O-labelled acetic acid. PMID:28128196

  2. An efficient synthesis of loline alkaloids

    NASA Astrophysics Data System (ADS)

    Cakmak, Mesut; Mayer, Peter; Trauner, Dirk

    2011-07-01

    Loline (1) is a small alkaloid that, in spite of its simple-looking structure, has posed surprising challenges to synthetic chemists. It has been known for more than a century and has been the subject of extensive biological investigations, but only two total syntheses have been achieved to date. Here, we report an asymmetric total synthesis of loline that, with less then ten steps, is remarkably short. Our synthesis incorporates a Sharpless epoxidation, a Grubbs olefin metathesis and an unprecedented transannular aminobromination, which converts an eight-membered cyclic carbamate into a bromopyrrolizidine. The synthesis is marked by a high degree of chemo- and stereoselectivity and gives access to several members of the loline alkaloid family. It delivers sufficient material to support a programme aimed at studying the complex interactions between plants, fungi, insects and bacteria brokered by loline alkaloids.

  3. Green Chemistry Techniques for Gold Nanoparticles Synthesis

    NASA Astrophysics Data System (ADS)

    Cannavino, Sarah A.; King, Christy A.; Ferrara, Davon W.

    Gold nanoparticles (AuNPs) are often utilized in many technological and research applications ranging from the detection of tumors, molecular and biological sensors, and as nanoantennas to probe physical processes. As these applications move from the research laboratory to industrial settings, there is a need to develop efficient and sustainable synthesis techniques. Recent research has shown that several food products and beverages containing polyphenols, a common antioxidant, can be used as reducing agents in the synthesis of AuNPs in solution. In this study, we explore a variety of products to determine which allow for the most reproducible solution of nanoparticles based on the size and shapes of particles present. We analyzed the AuNPs solutions using extinction spectroscopy and atomic force microscopy. We also develop a laboratory activity to introduce introductory chemistry and physics students to AuNP synthesis techniques and analysis.

  4. Unifying Gate Synthesis and Magic State Distillation

    NASA Astrophysics Data System (ADS)

    Campbell, Earl T.; Howard, Mark

    2017-02-01

    The leading paradigm for performing a computation on quantum memories can be encapsulated as distill-then-synthesize. Initially, one performs several rounds of distillation to create high-fidelity magic states that provide one good T gate, an essential quantum logic gate. Subsequently, gate synthesis intersperses many T gates with Clifford gates to realize a desired circuit. We introduce a unified framework that implements one round of distillation and multiquibit gate synthesis in a single step. Typically, our method uses the same number of T gates as conventional synthesis but with the added benefit of quadratic error suppression. Because of this, one less round of magic state distillation needs to be performed, leading to significant resource savings.

  5. Alkoxyallenes as building blocks for organic synthesis.

    PubMed

    Zimmer, Reinhold; Reissig, Hans-Ulrich

    2014-05-07

    Alkoxyallenes are unusually versatile C3 building blocks in organic synthesis. Hence this tutorial review summarizes the most important transformations, including subsequent reactions and their applications in the synthesis of relevant compounds, e.g. natural products. The reactivity patterns involved and the synthons derived from alkoxyallenes are presented. Often alkoxyallenes can serve as substitutes of acrolein or acrolein acetals, utilisation of which has already led to interesting products. Most important is the use of lithiated alkoxyallenes which smoothly react with a variety of electrophiles and lead to products with unique substitution patterns. The heterocycles or carbocycles formed are intermediates for the stereoselective synthesis of natural products or for the preparation of other structurally relevant compounds. The different synthons being put into practice by the use of lithiated alkoxyallenes in these variations will be discussed.

  6. Dimensional synthesis of a leg mechanism

    NASA Astrophysics Data System (ADS)

    Pop, F.; Lovasz, E.-Ch; Pop, C.; Dolga, V.

    2016-08-01

    An eight bar leg mechanism dimensional synthesis is presented. The mathematical model regarding the synthesis is described and the results obtained after computation are verified with help of 2D mechanism simulation in Matlab. This mechanism, inspired from proposed solution of Theo Jansen, is integrated into the structure of a 2 DOF quadruped robot. With help of the kinematic synthesis method described, it is tried to determine new dimensions for the mechanism, based on a set of initial conditions. These are established by taking into account the movement of the end point of the leg mechanism, which enters in contact with the ground, during walking. An optimization process based on the results obtained can be conducted further in order to find a better solution for the leg mechanism.

  7. Introduction to special section on Hydrologic Synthesis

    SciTech Connect

    Hubbard, Susan

    2006-01-23

    The Hydrological Synthesis special section presentssynthesis topics that have the potential to revolutionize hydrologicalsciences in a manner needed to meet critical water challenges that we nowface. The special section also highlights topics that are important andexciting enough to compel researchers to engage in collaborativesynthesis activities. This introductory paper provides a brief overviewof nine papers that are included in this special section, which discussthe synthesis of tools, data, concepts, theories, or approaches acrossdisciplines and scales. The wide range of topics that are exploredinclude groundwater quality, river restoration, water management,nitrogen cycling, and Earth surface dynamics. Collectively, the specialsection papers illustrate that the challenge to deal effectively withcomplex water problems is not purely a scientific, technological, orsocioeconomic one; it is instead a complex, 21st century problem thatrequires coordinated synthesis.

  8. Synthesis and Understanding of Novel Catalysts

    SciTech Connect

    Stair, Peter C.

    2013-07-09

    The research took advantage of our capabilities to perform in-situ and operando Raman spectroscopy on complex systems along with our developing expertise in the synthesis of uniform, supported metal oxide materials to investigate relationships between the catalytically active oxide composition, atomic structure, and support and the corresponding chemical and catalytic properties. The project was organized into two efforts: 1) Synthesis of novel catalyst materials by atomic layer deposition (ALD). 2) Spectroscopic and chemical investigations of coke formation and catalyst deactivation. ALD synthesis was combined with conventional physical characterization, Raman spectroscopy, and probe molecule chemisorption to study the effect of supported metal oxide composition and atomic structure on acid-base and catalytic properties. Operando Raman spectroscopy studies of olefin polymerization leading to coke formation and catalyst deactivation clarified the mechanism of coke formation by acid catalysts.

  9. Enzymatic synthesis of cinnamic acid derivatives.

    PubMed

    Lee, Gia-Sheu; Widjaja, Arief; Ju, Yi-Hsu

    2006-04-01

    Using Novozym 435 as catalyst, the syntheses of ethyl ferulate (EF) from ferulic acid (4-hydroxy 3-methoxy cinnamic acid) and ethanol, and octyl methoxycinnamate (OMC) from p-methoxycinnamic acid and 2-ethyl hexanol were successfully carried out in this study. A conversion of 87% was obtained within 2 days at 75 degrees C for the synthesis of EF. For the synthesis of OMC at 80 degrees C, 90% conversion can be obtained within 1 day. The use of solvent and high reaction temperature resulted in better conversion for the synthesis of cinnamic acid derivatives. Some cinnamic acid esters could also be obtained with higher conversion and shorter reaction times in comparison to other methods reported in the literature. The enzyme can be reused several times before significant activity loss was observed.

  10. Total synthesis of zyzzyanones A-D

    PubMed Central

    Nadkarni, Dwayaja H.; Murugesan, Srinivasan

    2013-01-01

    Zyzzyanones A-D is a group of biologically active marine alkaloids isolated from Australian marine sponge Zyzzya fuliginosa. They contain a unique bispyrroloquinone ring system as the core structure. The first total synthesis of all four zyzzyanones is described here. The synthesis of these alkaloids started from a previously known 6-benzylamino indole-4,7-quinone derivative and involves 6–7 steps. The key step in the synthesis involves the construction of a pyrrole ring in one step using a Mn(OAc)3 mediated oxidative free radical cyclization reaction of a 6-benzylamino indole-4,7-quinone derivative with 4-benzyloxyphenyl acetaldehyde diethyl acetal in CH3CN. PMID:23956468

  11. Quantum chemistry-assisted synthesis route development

    NASA Astrophysics Data System (ADS)

    Hori, Kenji; Sumimoto, Michinori; Murafuji, Toshihiro

    2015-12-01

    We have been investigating "quantum chemistry-assisted synthesis route development" using in silico screenings and applied the method to several targets. Another example was conducted to develop synthesis routes for a urea derivative, namely 1-(4-(trifluoromethyl)-2-oxo-2H-chromen-7-yl)urea. While five synthesis routes were examined, only three routes passed the second in silico screening. Among them, the reaction of 7-amino-4-(trifluoromethyl)-2H-chromen-2-one and O-methyl carbamate with BF3 as an additive was ranked as the first choice for synthetic work. We were able to experimentally obtain the target compound even though its yield was as low as 21 %. The theoretical result was thus consistent with that observed. The summary of transition state data base (TSDB) is also provided. TSDB is the key to reducing time of in silico screenings.

  12. Photocatalysis in organic and polymer synthesis.

    PubMed

    Corrigan, Nathaniel; Shanmugam, Sivaprakash; Xu, Jiangtao; Boyer, Cyrille

    2016-11-07

    This review, with over 600 references, summarizes the recent applications of photoredox catalysis for organic transformation and polymer synthesis. Photoredox catalysts are metallo- or organo-compounds capable of absorbing visible light, resulting in an excited state species. This excited state species can donate or accept an electron from other substrates to mediate redox reactions at ambient temperature with high atom efficiency. These catalysts have been successfully implemented for the discovery of novel organic reactions and synthesis of added-value chemicals with an excellent control of selectivity and stereo-regularity. More recently, such catalysts have been implemented by polymer chemists to post-modify polymers in high yields, as well as to effectively catalyze reversible deactivation radical polymerizations and living polymerizations. These catalysts create new approaches for advanced organic transformation and polymer synthesis. The objective of this review is to give an overview of this emerging field to organic and polymer chemists as well as materials scientists.

  13. Pyranonaphthoquinones - isolation, biology and synthesis: an update.

    PubMed

    Naysmith, Briar J; Hume, Paul A; Sperry, Jonathan; Brimble, Margaret A

    2017-01-04

    Covering: 2008 to 2015. A review on the isolation, biological activity and synthesis of pyranonaphthoquinone natural products from 2008-2015 is providedThis review discusses the isolation, biological activity and synthesis of pyranonaphthoquinone natural products, covering the years 2008-2015. The pyranonaphthoquinones are a group of metabolites sharing a common naphtho[2,3-c]pyran-5,10-dione ring system that have been isolated from a wide range of microorganisms, plants and insects. In addition to their synthetically challenging molecular structures, pyranonaphthoquinones exhibit a wide array of biological activity, including anti-bacterial, anti-fungal and anti-cancer properties. The therapeutic potential of these compounds has led to a dynamic interplay between total synthesis and biological evaluation.

  14. Quantum chemistry-assisted synthesis route development

    SciTech Connect

    Hori, Kenji; Sumimoto, Michinori; Murafuji, Toshihiro

    2015-12-31

    We have been investigating “quantum chemistry-assisted synthesis route development” using in silico screenings and applied the method to several targets. Another example was conducted to develop synthesis routes for a urea derivative, namely 1-(4-(trifluoromethyl)-2-oxo-2H-chromen-7-yl)urea. While five synthesis routes were examined, only three routes passed the second in silico screening. Among them, the reaction of 7-amino-4-(trifluoromethyl)-2H-chromen-2-one and O-methyl carbamate with BF{sub 3} as an additive was ranked as the first choice for synthetic work. We were able to experimentally obtain the target compound even though its yield was as low as 21 %. The theoretical result was thus consistent with that observed. The summary of transition state data base (TSDB) is also provided. TSDB is the key to reducing time of in silico screenings.

  15. Myosin synthesis in embryonic chicken fibroblasts

    PubMed Central

    1979-01-01

    The rate of constitutive myosin synthesis was measured in cultures of replicating embryonic chicken skin fibroblasts by pulse labeling with [3H]leucine. These cells synthesized the 200,000-dalton heavy chain of myosin (MHC) at a rate of 3.2 x 10(3) molecules/cell/min. Additionally, an independent estimate of the MHC synthesis rate needed to maintain a constant level of constitutive MHC/cell was calculated from total protein content, percentage MHC, fibroblast doubling time, and MHC half- life. This calculated rate of approximately 2.9 x 10(3) molecules/cell/min was in close agreement with the measured rate. By comparison, the synthesis rate of myofibrillar MHC in fully activated muscle cell cultures was approximately 2.9 x 10(4) molecules/nucleus/min. PMID:479285

  16. Synthesis of alpha-amino acids

    DOEpatents

    Davis, J.W. Jr.

    1983-01-25

    A method is described for synthesizing alpha amino acids proceeding through novel intermediates of the formulas: R[sub 1]R[sub 2]C(OSOCl)CN, R[sub 1]R[sub 2]C(Cl)CN and [R[sub 1]R[sub 2]C(CN)O][sub 2]SO wherein R[sub 1] and R[sub 2] are each selected from hydrogen monovalent substituted and unsubstituted hydrocarbon radicals of 1 to 10 carbon atoms. The use of these intermediates allows the synthesis steps to be exothermic and results in an overall synthesis method which is faster than the synthesis methods of the prior art. No Drawings

  17. Protein Synthesis Initiation Factors: Phosphorylation and Regulation

    SciTech Connect

    Karen S. Browning

    2009-06-15

    The initiation of the synthesis of proteins is a fundamental process shared by all living organisms. Each organism has both shared and unique mechanisms for regulation of this vital process. Higher plants provide for a major amount of fixation of carbon from the environment and turn this carbon into food and fuel sources for our use. However, we have very little understanding of how plants regulate the synthesis of the proteins necessary for these metabolic processes. The research carried out during the grant period sought to address some of these unknowns in the regulation of protein synthesis initiation. Our first goal was to determine if phosphorylation plays a significant role in plant initiation of protein synthesis. The role of phosphorylation, although well documented in mammalian protein synthesis regulation, is not well studied in plants. We showed that several of the factors necessary for the initiation of protein synthesis were targets of plant casein kinase and showed differential phosphorylation by the plant specific isoforms of this kinase. In addition, we identified and confirmed the phosphorylation sites in five of the plant initiation factors. Further, we showed that phosphorylation of one of these factors, eIF5, affected the ability of the factor to participate in the initiation process. Our second goal was to develop a method to make initiation factor 3 (eIF3) using recombinant methods. To date, we successfully cloned and expressed 13/13 subunits of wheat eIF3 in E. coli using de novo gene construction methods. The final step in this process is to place the subunits into three different plasmid operons for co-expression. Successful completion of expression of eIF3 will be an invaluable tool to the plant translation community.

  18. Prebiotic RNA Synthesis by Montmorillonite Catalysis

    NASA Astrophysics Data System (ADS)

    Jheeta, Sohan; Joshi, Prakash C.

    2014-08-01

    This review summarizes our recent findings on the role of mineral salts in prebiotic RNA synthesis, which is catalyzed by montmorillonite clay minerals. The clay minerals not only catalyze the synthesis of RNA but also facilitate homochiral selection. Preliminary data of these findings have been presented at the "Horizontal Gene Transfer and the Last Universal Common Ancestor (LUCA)" conference at the Open University, Milton Keynes, UK, 5-6 September 2013. The objective of this meeting was to recognize the significance of RNA in LUCA. We believe that the prebiotic RNA synthesis from its monomers must have been a simple process. As a first step, it may have required activation of the 5'-end of the mononucleotide with a leaving group, e.g., imidazole in our model reaction (Figure 1). Wide ranges of activating groups are produced from HCN under plausible prebiotic Earth conditions. The final step is clay mineral catalysis in the presence of mineral salts to facilitate selective production of functional RNA. Both the clay minerals and mineral salts would have been abundant on early Earth. We have demonstrated that while montmorillonite (pH 7) produced only dimers from its monomers in water, addition of sodium chloride (1 M) enhanced the chain length multifold, as detected by HPLC. The effect of monovalent cations on RNA synthesis was of the following order: Li+ > Na+ > K+. A similar effect was observed with the anions, enhancing catalysis in the following order: Cl- > Br- > I-. The montmorillonite-catalyzed RNA synthesis was not affected by hydrophobic or hydrophilic interactions. We thus show that prebiotic synthesis of RNA from its monomers was a simple process requiring only clay minerals and a small amount of salt.

  19. Prebiotic RNA Synthesis by Montmorillonite Catalysis

    PubMed Central

    Jheeta, Sohan; Joshi, Prakash C.

    2014-01-01

    This review summarizes our recent findings on the role of mineral salts in prebiotic RNA synthesis, which is catalyzed by montmorillonite clay minerals. The clay minerals not only catalyze the synthesis of RNA but also facilitate homochiral selection. Preliminary data of these findings have been presented at the “Horizontal Gene Transfer and the Last Universal Common Ancestor (LUCA)” conference at the Open University, Milton Keynes, UK, 5–6 September 2013. The objective of this meeting was to recognize the significance of RNA in LUCA. We believe that the prebiotic RNA synthesis from its monomers must have been a simple process. As a first step, it may have required activation of the 5'-end of the mononucleotide with a leaving group, e.g., imidazole in our model reaction (Figure 1). Wide ranges of activating groups are produced from HCN under plausible prebiotic Earth conditions. The final step is clay mineral catalysis in the presence of mineral salts to facilitate selective production of functional RNA. Both the clay minerals and mineral salts would have been abundant on early Earth. We have demonstrated that while montmorillonite (pH 7) produced only dimers from its monomers in water, addition of sodium chloride (1 M) enhanced the chain length multifold, as detected by HPLC. The effect of monovalent cations on RNA synthesis was of the following order: Li+ > Na+ > K+. A similar effect was observed with the anions, enhancing catalysis in the following order: Cl− > Br− > I−. The montmorillonite-catalyzed RNA synthesis was not affected by hydrophobic or hydrophilic interactions. We thus show that prebiotic synthesis of RNA from its monomers was a simple process requiring only clay minerals and a small amount of salt. PMID:25370375

  20. Unified Synthesis Product (USP) Recommendations

    NASA Astrophysics Data System (ADS)

    Peterson, T. C.

    2009-05-01

    The USP identifies a number of areas in which inadequate information or understanding hampers our ability to estimate likely future climate change and its impacts. For example, our knowledge of changes in tornadoes, hail, and ice storms is quite limited, making it difficult to know if and how such events have changed as climate has warmed, and how they might change in the future. Research on ecological responses to climate change also is limited, as is our understanding of social responses. The Report identifies the five most important gaps in knowledge and offers some thoughts on how to address those gaps: 1. Expand our understanding of climate change impacts. There is a clear need to increase understanding of how ecosystems, social and economic systems, human health, and the built environment will be affected by climate change in the context of other stresses. This includes ecosystems as well as economic systems, human health, and the built environment. 2. Refine ability to project climate change at local scales. One of the main messages to emerge from the past decade of synthesis and assessments is that while climate change is a global issue, it has a great deal of regional variability. There is an indisputable need to improve understanding of climate system effects at these smaller scales, because these are often the scales of decision-making in society. 3. Expand capacity to provide decision makers and the public with relevant information on climate change and its impacts. The United States has tremendous potential to create more comprehensive measurement, archive, and data-access systems that could provide great benefit to society. 4. Improve understanding of and ability to identify thresholds likely to lead to abrupt changes in the climate system. Paleoclimatic data shows that climate can and has changed quite abruptly when certain thresholds are crossed. Similarly, there is evidence that ecological and human systems can undergo abrupt change when tipping

  1. Nonrenal regulation of EPO synthesis.

    PubMed

    Weidemann, Alexander; Johnson, Randall S

    2009-04-01

    Erythropoietin (EPO) is a circulating glycoprotein hormone whose principal function is thought to be red blood cell production. It is a classic example of a hypoxia-inducible gene, and studies of the induction of EPO synthesis by low oxygen led to the discovery of a widespread system of hypoxia-inducible transcription factors. Tissue-specific expression of the EPO gene is tightly controlled, and in the adult organism the kidney produces around 90% of systemic EPO. Before birth, the liver is the main site of EPO production; factors contributing to the liver-to-kidney switch are still elusive, but may provide clues to the tissue-specificity of EPO gene expression. EPO has also been detected in non-erythropoietic tissues such as the brain, where it is suggested to exert local protective effects. Apart from classical ways of regulating renal EPO during hypoxia and anemia, novel pathways have been discovered that demonstrate that other organ systems in the adult might not only be important for the production of EPO but also for modulating the hypoxic EPO response. Knowledge of the molecular bases of these non-renal pathways will eventually help to develop pharmacological strategies to induce endogenous EPO production when the main source, the kidney, is significantly impaired. This review will provide an overview of the molecular aspects of EPO gene regulation by hypoxia-inducible transcription factors and of the tissue-specific regulation of EPO production in adult mammals. Insights into the biology of EPO production in genetically modified animals, with an emphasis on recent advances in the understanding of non-renal EPO regulation, will be discussed.

  2. Combustion Synthesis of Magnesium Aluminate

    SciTech Connect

    Kale, M. A.; Joshi, C. P.; Moharil, S. V.

    2011-10-20

    In the system MgO-Al{sub 2}O{sub 3}, three compounds MgAl{sub 2}O{sub 4}, MgAl{sub 6}O{sub 10}(also expressed as-Mg{sub 0.4}Al{sub 2.4}O{sub 4}) and MgAl{sub 26}O{sub 40} are well known. Importance of the first two is well established. Magnesium aluminate (MgAl{sub 2}O{sub 4}) spinel is a technologically important material due to its interesting thermal properties. The MgAl{sub 2}O{sub 4} ceramics also find application as humidity sensors. Apart from the luminescence studies, the interest in MgAl{sub 2}O{sub 4} is due to various applications such as humidity-sensing and PEM fuel cells, TL/OSL dosimetry of the ionizing radiations, white light source. Interest in the MgAl{sub 6}O{sub 10} has aroused due to possible use as a substrate for GaN growth. Attempt was made to synthesize these compounds by the combustion synthesis using metal nitrates as oxidizer and urea as a fuel. Compounds MgAl{sub 2}O{sub 4} and MgAl{sub 6}O{sub 10} were formed in a single step, while MgAl{sub 26}O{sub 40} was not formed by this procedure. Activation of MgAl{sub 6}O{sub 10} by rare earth ions like Ce{sup 3+}, Eu{sup 3+} and Tb{sup 3+} and ns{sup 2} ion Pb{sup 2+} could be achieved. Excitation bands for MgAl{sub 6}O{sub 10} are at slightly shorter wavelengths compared to those reported for MgAl{sub 2}O{sub 4}.

  3. Hydroxamic Acids in Asymmetric Synthesis

    PubMed Central

    Li, Zhi; Yamamoto, Hisashi

    2012-01-01

    Metal-catalyzed stereoselective reactions are a central theme in organic chemistry research. In these reactions, the stereoselection is achieved predominantly by introducing chiral ligands at the metal catalyst’s center. For decades, researchers have sought better chiral ligands for asymmetric catalysis and have made great progress. Nevertheless, to achieve optimal stereoselectivity and to catalyze new reactions, new chiral ligands are needed. Due to their high metal affinity, hydroxamic acids play major roles across a broad spectrum of fields from biochemistry to metal extraction. Dr. K. Barry Sharpless first revealed their potential as chiral ligands for asymmetric synthesis in 1977: He published the chiral vanadium-hydroxamic-acid-catalyzed, enantioselective epoxidation of allylic alcohols before his discovery of Sharpless Asymmetric Epoxidation, which uses titanium-tartrate complex as the chiral reagent. However, researchers have reported few highly enantioselective reactions using metal-hydroxamic acid as catalysts since then. This Account summarizes our research on metal-catalyzed asymmetric epoxidation using hydroxamic acids as chiral ligands. We designed and synthesized a series of new hydroxamic acids, most notably the C2-symmetric bis-hydroxamic acid (BHA) family. V-BHA-catalyzed epoxidation of allylic and homoallylic alcohols achieved higher activity and stereoselectivity than Sharpless Asymmetric Epoxidation in many cases. Changing the metal species led to a series of unprecedented asymmetric epoxidation reactions, such as (i) single olefins and sulfides with Mo-BHA, (ii) homoallylic and bishomoallylic alcohols with Zr- and Hf-BHA, and (iii) N-alkenyl sulfonamides and N-sulfonyl imines with Hf-BHA. These reactions produce uniquely functionalized chiral epoxides with good yields and enantioselectivities. PMID:23157425

  4. Enantioselective Total Synthesis of Tricyclic Myrmicarin Alkaloids

    PubMed Central

    Movassaghi, Mohammad; Ondrus, Alison E.

    2010-01-01

    An enantioselective gram-scale synthesis of a key dihydroindolizine intermediate for the preparation of myrmicarin alkaloids is described. Key transformations in this convergent approach include a stereospecific palladium–catalyzed N-vinylation of a pyrrole with a vinyl triflate, a copper–catalyzed enantioselective conjugate reduction of a β-pyrrolyl enoate, and a regioselective Friedel-Crafts reaction. The synthesis of optically active and isomerically pure samples of (4aR)-myrmicarins 215A, 215B, and 217 in addition to their respective C4a-epimers is presented. PMID:16178549

  5. Tailored fischer-tropsch synthesis product distribution

    DOEpatents

    Wang, Yong [Richland, WA; Cao, Chunshe [Kennewick, WA; Li, Xiaohong Shari [Richland, WA; Elliott, Douglas C [Richland, WA

    2012-06-19

    Novel methods of Fischer-Tropsch synthesis are described. It has been discovered that conducting the Fischer-Tropsch synthesis over a catalyst with a catalytically active surface layer of 35 microns or less results in a liquid hydrocarbon product with a high ratio of C.sub.5-C.sub.20:C.sub.20+. Descriptions of novel Fischer-Tropsch catalysts and reactors are also provided. Novel hydrocarbon compositions with a high ratio of C.sub.5-C.sub.20:C.sub.20+ are also described.

  6. Synthesis of Alkyl Methylphosphonic Acid Esters

    SciTech Connect

    Mong, Gary M.; Harvey, Scott D.; Campbell, James A.

    2005-08-01

    This manuscript describes a simple synthesis and purification of cyclohexyl methylphosphonic and isopropyl methylphosphonic acids that provides high purity (>95% purity) product in gram quantities. Based on needs for improved analytical methods for indirect detection of nerve agent use, there is an increasing demand for these nerve agent hydrolysis products. These products are not commercially available. Synthesis is based on reaction of equimolar amounts of alcohol with methylphosphonic dichloride in toluene followed by the addition of excess water (two mole equivalents). The product was then extracted from the resulting aqueous layer into chloroform. The extraction scheme proved highly effective in removing unreacted starting materials and reaction by-products.

  7. Rational design and synthesis of Janus composites.

    PubMed

    Liang, Fuxin; Zhang, Chengliang; Yang, Zhenzhong

    2014-10-29

    Janus composites with two different components divided on the same object have gained growing interest in many fields, such as solid emulsion stabilizers, sensors, optical probes and self-propellers. Over the past twenty years, various synthesis methods have been developed including Pickering emulsion interfacial modification, block copolymer self-assembly, microfluidics, electro co-jetting, and swelling emulsion polymerization. Anisotropic shape and asymmetric spatial distribution of compositions and functionalities determine their unique performances. Rational design and large scale synthesis of functional Janus materials are crucial for the systematical characterization of performance and exploitation of practical applications.

  8. Acylsilanes: valuable organosilicon reagents in organic synthesis.

    PubMed

    Zhang, Hui-Jun; Priebbenow, Daniel L; Bolm, Carsten

    2013-11-07

    Acylsilanes are a fascinating class of compounds that display a number of distinctive chemical and physical properties. The unique reactivity pattern of the acylsilane functional group [R-C(O)Si] makes them an increasingly attractive moiety in modern organic synthesis, and as such, they have been utilised in a diverse range of transformations. This review provides an overview of the recent advances in the synthesis and application of acylsilanes in organic chemistry, with a particular focus on the progress made in the last two decades.

  9. Graphene Oxide Synthesis from Agro Waste

    PubMed Central

    Somanathan, Thirunavukkarasu; Prasad, Karthika; Ostrikov, Kostya (Ken); Saravanan, Arumugam; Mohana Krishna, Vemula

    2015-01-01

    A new method of graphene oxide (GO) synthesis via single-step reforming of sugarcane bagasse agricultural waste by oxidation under muffled atmosphere conditions is reported. The strong and sharp X-ray diffraction peak at 2θ = 11.6° corresponds to an interlayer distance of 0.788 nm (d002) for the AB stacked GOs. High-resolution transmission electron microscopy (HRTEM) and selected-area electron diffraction (SAED) confirm the formation of the GO layer structure and the hexagonal framework. This is a promising method for fast and effective synthesis of GO from sugarcane bagasse intended for a variety of energy and environmental applications. PMID:28347038

  10. Camera-enabled techniques for organic synthesis

    PubMed Central

    Ingham, Richard J; O’Brien, Matthew; Browne, Duncan L

    2013-01-01

    Summary A great deal of time is spent within synthetic chemistry laboratories on non-value-adding activities such as sample preparation and work-up operations, and labour intensive activities such as extended periods of continued data collection. Using digital cameras connected to computer vision algorithms, camera-enabled apparatus can perform some of these processes in an automated fashion, allowing skilled chemists to spend their time more productively. In this review we describe recent advances in this field of chemical synthesis and discuss how they will lead to advanced synthesis laboratories of the future. PMID:23766820

  11. Tactical Synthesis Of Efficient Global Search Algorithms

    NASA Technical Reports Server (NTRS)

    Nedunuri, Srinivas; Smith, Douglas R.; Cook, William R.

    2009-01-01

    Algorithm synthesis transforms a formal specification into an efficient algorithm to solve a problem. Algorithm synthesis in Specware combines the formal specification of a problem with a high-level algorithm strategy. To derive an efficient algorithm, a developer must define operators that refine the algorithm by combining the generic operators in the algorithm with the details of the problem specification. This derivation requires skill and a deep understanding of the problem and the algorithmic strategy. In this paper we introduce two tactics to ease this process. The tactics serve a similar purpose to tactics used for determining indefinite integrals in calculus, that is suggesting possible ways to attack the problem.

  12. Synthesis and structures of metal chalcogenide precursors

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Duraj, Stan A.; Eckles, William E.; Andras, Maria T.

    1990-01-01

    The reactivity of early transition metal sandwich complexes with sulfur-rich molecules such as dithiocarboxylic acids was studied. Researchers recently initiated work on precursors to CuInSe2 and related chalcopyrite semiconductors. Th every high radiation tolerance and the high absorption coefficient of CuInSe2 makes this material extremely attractive for lightweight space solar cells. Their general approach in early transition metal chemistry, the reaction of low-valent metal complexes or metal powders with sulfur and selenium rich compounds, was extended to the synthesis of chalcopyrite precursors. Here, the researchers describe synthesis, structures, and and routes to single molecule precursors to metal chalcogenides.

  13. Synthesis of alpha-amino acids

    DOEpatents

    Davis, Jr., Jefferson W.

    1983-01-01

    A method for synthesizing alpha amino acids proceding through novel intermediates of the formulas: R.sub.1 R.sub.2 C(OSOCl)CN, R.sub.1 R.sub.2 C(Cl)CN and [R.sub.1 R.sub.2 C(CN)O].sub.2 SO wherein R.sub.1 and R.sub.2 are each selected from hydrogen monovalent substituted and unsubstituted hydrocarbon radicals of 1 to 10 carbon atoms. The use of these intermediates allows the synthesis steps to be exothermic and results in an overall synthesis method which is faster than the snythesis methods of the prior art.

  14. Synthesis of (+)-Discodermolide by Catalytic Stereoselective Borylation Reactions**

    PubMed Central

    Yu, Zhiyong; Ely, Robert J.

    2014-01-01

    The marine natural product (+)-discodermolide was first isolated in 1990 and, to this day, remains a compelling synthesis target. Not only does the compound possess fascinating biological activity, but it also presents an opportunity to test current methods for chemical synthesis and provides a forum for the inspiration of new reaction development. In this manuscript, we present a synthesis of discodermolide that employs a previously undisclosed stereoselective catalytic diene hydroboration and also establishes a strategy for chiral enolate alkylation. In addition, this synthesis of discodermolide provides the first examples of diene 1,4-diboration and borylative diene-aldehyde couplings in complex molecule synthesis. PMID:25045037

  15. Toward synthesis of the regular sequence of heparin: synthesis of two tetrasaccharide precursors.

    PubMed

    Zhou, Ying; Lin, Feng; Chen, Jianfang; Yu, Biao

    2006-07-24

    Two fully protected tetrasaccharides, which represent precursors for the synthesis of the regular sequence of heparin, were synthesized via coupling of a pair of disaccharide trichloroacetimidates with a thioglycoside and a glucosamine derivative, respectively, in a sequential manner.

  16. Ubiquinone synthesis and its regulation in Pneumocystis carinii.

    PubMed

    Kaneshiro, Edna S; Basselin, Mireille; Merali, Salim; Kayser, Oliver

    2006-01-01

    The opportunistic pathogen Pneumocystis causes a type of pneumonia in individuals with defective immune systems such as AIDS patients. Atovaquone, an analog of ubiquinone (coenzyme Q [CoQ]), is effective in clearing mild to moderate cases of the infection. Rat-derived Pneumocystis carinii was the first organism in which CoQ synthesis was clearly demonstrated to occur in both mitochondrial and microsomal subcellular fractions. Atovaquone inhibits microsomal CoQ synthesis with no effect on mitochondrial CoQ synthesis. We here report on additional studies evaluating CoQ synthesis and its regulation in the organism. Buparvaquone also inhibited CoQ synthesis and it reduced the synthesis of all four CoQ homologs in the microsomal but not the mitochondrial fraction. Glyphosate, which inhibits a reaction in the de novo synthesis of the benzoquinone moiety of CoQ reduced cellular ATP levels. Bacterial and plant quinones, and several chemically synthesized phenolics, flavanoids, and naphthoquinones that inhibit electron transport in other organisms were shown to reduce CoQ synthesis in P. carinii. The inhibitory action of naphthoquinone compounds appeared to depend on their molecular size and structural flexibility rather than redox potential. Results of experiments examining the synthesis of the polyprenyl chain of CoQ were consistent with negative feedback control of CoQ synthesis. These studies on P. carinii suggest that cellular sites and the control of CoQ synthesis in different organisms and cell types might be more diverse than previously thought.

  17. Haematopoietic stem cells require a highly regulated protein synthesis rate.

    PubMed

    Signer, Robert A J; Magee, Jeffrey A; Salic, Adrian; Morrison, Sean J

    2014-05-01

    Many aspects of cellular physiology remain unstudied in somatic stem cells, for example, there are almost no data on protein synthesis in any somatic stem cell. Here we set out to compare protein synthesis in haematopoietic stem cells (HSCs) and restricted haematopoietic progenitors. We found that the amount of protein synthesized per hour in HSCs in vivo was lower than in most other haematopoietic cells, even if we controlled for differences in cell cycle status or forced HSCs to undergo self-renewing divisions. Reduced ribosome function in Rpl24(Bst/+) mice further reduced protein synthesis in HSCs and impaired HSC function. Pten deletion increased protein synthesis in HSCs but also reduced HSC function. Rpl24(Bst/+) cell-autonomously rescued the effects of Pten deletion in HSCs; blocking the increase in protein synthesis, restoring HSC function, and delaying leukaemogenesis. Pten deficiency thus depletes HSCs and promotes leukaemia partly by increasing protein synthesis. Either increased or decreased protein synthesis impairs HSC function.

  18. DNA-Encoded Solid-Phase Synthesis: Encoding Language Design and Complex Oligomer Library Synthesis

    PubMed Central

    2015-01-01

    The promise of exploiting combinatorial synthesis for small molecule discovery remains unfulfilled due primarily to the “structure elucidation problem”: the back-end mass spectrometric analysis that significantly restricts one-bead-one-compound (OBOC) library complexity. The very molecular features that confer binding potency and specificity, such as stereochemistry, regiochemistry, and scaffold rigidity, are conspicuously absent from most libraries because isomerism introduces mass redundancy and diverse scaffolds yield uninterpretable MS fragmentation. Here we present DNA-encoded solid-phase synthesis (DESPS), comprising parallel compound synthesis in organic solvent and aqueous enzymatic ligation of unprotected encoding dsDNA oligonucleotides. Computational encoding language design yielded 148 thermodynamically optimized sequences with Hamming string distance ≥ 3 and total read length <100 bases for facile sequencing. Ligation is efficient (70% yield), specific, and directional over 6 encoding positions. A series of isomers served as a testbed for DESPS’s utility in split-and-pool diversification. Single-bead quantitative PCR detected 9 × 104 molecules/bead and sequencing allowed for elucidation of each compound’s synthetic history. We applied DESPS to the combinatorial synthesis of a 75 645-member OBOC library containing scaffold, stereochemical and regiochemical diversity using mixed-scale resin (160-μm quality control beads and 10-μm screening beads). Tandem DNA sequencing/MALDI-TOF MS analysis of 19 quality control beads showed excellent agreement (<1 ppt) between DNA sequence-predicted mass and the observed mass. DESPS synergistically unites the advantages of solid-phase synthesis and DNA encoding, enabling single-bead structural elucidation of complex compounds and synthesis using reactions normally considered incompatible with unprotected DNA. The widespread availability of inexpensive oligonucleotide synthesis, enzymes, DNA sequencing, and

  19. Spiro[2.4]hepta-4,6-dienes: synthesis and application in organic synthesis

    NASA Astrophysics Data System (ADS)

    Menchikov, L. G.; Nefedov, O. M.

    2016-03-01

    This review integrates and describes systematically the data in the field of spiro[2.4]hepta-4,6-dienes published in the past 15 years. The changes in the development of studies that took place during this period are noted. The methods for the synthesis, the reactivity details and key chemical transformations of spiro[2.4]hepta-4,6-dienes are considered, with the emphasis on applications of these compounds in organic synthesis. The bibliography includes 207 references.

  20. Improved Synthesis of Geodken's Macrocycle through the Synthesis of the Dichloride Salt

    ERIC Educational Resources Information Center

    Niewahner, J. H.; Walters, Keith A.; Wagner, Ashley

    2007-01-01

    The three-step synthesis of Geodken's macrocycle, H[subscript 2]C[subscript 22]H[subscript 22]N[subscript 4], (5,14-dihydro-6,8,15,17-tetramethyldibenzo[b,i]-[1,4,8,11] tetraazacyclotetradecahexane), in an overall yield of 65% is described. By utilizing the synthesis of the macrocycle's dichloride salt, H[subscript 2]C[subscript 22]H[subscript…

  1. Scale study of direct synthesis of dimethyl ether from biomass synthesis gas.

    PubMed

    Lv, Yongxing; Wang, Tiejun; Wu, Chuangzhi; Ma, Longlong; Zhou, Yi

    2009-01-01

    We investigated the synthesis of dimethyl ether (DME) from biomass synthesis gas using a kind of hybrid catalyst consisting of methanol and HZSM-5 zeolite in a fixed-bed reactor in a 100 ton/year pilot plant. The biomass synthesis gas was produced by oxygen-rich gasification of corn core in a two-stage fixed bed. The results showed that CO conversions reached 82.00% and 73.55%, the selectivities for DME were 73.95% and 69.73%, and the space-time yields were 124.28 kg m(-3) h(-1) and 203.80 kg m(-3) h(-1) when gas hourly space velocities were 650 h(-1) and 1200 h(-1), respectively. Deoxidation and tar removal from biomass synthesis gas was critical to the stable operation of the DME synthesis system. Using single-pass synthesis, the H(2)/CO ratio improved from 0.98-1.17 to 2.12-2.22. The yield of DME would be increased greatly if the exhaust was reused after removal of the CO(2).

  2. Defining Life: Synthesis and Conclusions

    NASA Astrophysics Data System (ADS)

    Gayon, Jean

    2010-04-01

    The first part of the paper offers philosophical landmarks on the general issue of defining life. §1 defends that the recognition of “life” has always been and remains primarily an intuitive process, for the scientist as for the layperson. However we should not expect, then, to be able to draw a definition from this original experience, because our cognitive apparatus has not been primarily designed for this. §2 is about definitions in general. Two kinds of definition should be carefully distinguished: lexical definitions (based upon current uses of a word), and stipulative or legislative definitions, which deliberately assign a meaning to a word, for the purpose of clarifying scientific or philosophical arguments. The present volume provides examples of these two kinds of definitions. §3 examines three traditional philosophical definitions of life, all of which have been elaborated prior to the emergence of biology as a specific scientific discipline: life as animation (Aristotle), life as mechanism, and life as organization (Kant). All three concepts constitute a common heritage that structures in depth a good deal of our cultural intuitions and vocabulary any time we try to think about “life”. The present volume offers examples of these three concepts in contemporary scientific discourse. The second part of the paper proposes a synthesis of the major debates developed in this volume. Three major questions have been discussed. A first issue (§4) is whether we should define life or not, and why. Most authors are skeptical about the possibility of defining life in a strong way, although all admit that criteria are useful in contexts such as exobiology, artificial life and the origins of life. §5 examines the possible kinds of definitions of life presented in the volume. Those authors who have explicitly defended that a definition of life is needed, can be classified into two categories. The first category (or standard view) refers to two conditions

  3. Biomimetic synthesis of metallic nanowires

    NASA Astrophysics Data System (ADS)

    Carlsen, Autumn

    With the release of its 2007 Executive Summary, the International Technology Roadmap for Semiconductors acknowledged the growing relevance of novel materials by adding an entire chapter devoted to "Emerging Research Materials," in addition to the usual "Emerging Research Devices" chapter.1 This step represents a natural progression for a roadmap striving to reflect the dynamic approach by which the semiconductor industry maintains the trend known as Moore's Law---a prediction that functionality per chip doubles every 18 to 24 months.2 The steady march of miniaturization inevitably leads to consideration of a bottom-up approach. Novel materials---such as macromolecules and one-dimensional assemblies---are gaining ground in the research and development of future technologies. The first chapter of this document presents the limitations of the top-down approach and the resulting need for research into the bottom-up approach to nanowire fabrication. Chapter two delves into the wide range of published biotemplating studies---with candidate materials such as DNA, viruses, bacteria and polypeptides. The structure and challenges associated with each templating candidate are briefly discussed, followed by a summary of examples of successful metallization. The third chapter focuses on synthesis of the genetically engineered polypeptide employed in this investigation. Characterization of the polypeptide is presented in the form of atomic force microscopy (AFM) and transmission electron microscopy (TEM) data. The fourth chapter summarizes efforts to produce a gold nanowire by colloidal decoration. Evidence of decoration is presented in the form of data obtained by ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). Chapter five explores an alternate approach---reduction of fibril-bound metal ions. Two different reduction techniques are evaluated. Comparison is made of the

  4. Green Synthesis of a Fluorescent Natural Product

    ERIC Educational Resources Information Center

    Young, Douglas M.; Welker, Jacob J. C.; Doxsee, Kenneth M.

    2011-01-01

    Synthesis of 4-methylumbelliferone via the acid-catalyzed Pechmann condensation introduces students to several types of organic reactions: transesterification, electrophilic aromatic substitution, and alcohol dehydration. Performed with a recyclable, solid catalyst and under solvent-free conditions, the experiment illustrates many of the…

  5. Asymmetric synthesis of tertiary thiols and thioethers

    PubMed Central

    MacLellan, Paul

    2011-01-01

    Summary Enantiomerically pure tertiary thiols provide a major synthetic challenge, and despite the importance of chiral sulfur-containing compounds in biological and medicinal chemistry, surprisingly few effective methods are suitable for the asymmetric synthesis of tertiary thiols. This review details the most practical of the methods available. PMID:21647256

  6. Room temperature synthesis of biodiesel using sulfonated ...

    EPA Pesticide Factsheets

    Sulfonation of graphitic carbon nitride (g-CN) affords a polar and strongly acidic catalyst, Sg-CN, which displays unprecedented reactivity and selectivity in biodiesel synthesis and esterification reactions at room temperature. Prepared for submission to Royal Society of Chemistry (RSC) journal, Green Chemistry as a communication.

  7. Mechanochemical synthesis of layered hydroxy salts

    SciTech Connect

    Thomas, Nygil

    2012-11-15

    Highlights: ► Ultrafast synthesis method was developed for the synthesis of layered hydroxy salts. ► Preparation of hydroxy single salt by this method requires only one minute. ► Hydroxy salts with variable Ni/Zn ratio could be synthesized by varying the metal contents of the starting mixture. ► This synthesis method is solvent free and environment friendly. -- Abstract: A simple one minute synthesis method was adapted for the preparation of layered hydroxy salts of copper, zinc, nickel and cadmium by grinding the metal salts with sodium hydroxide in a mortar. This solvent free method is environment friendly and fast. This method could be extended to the preparation of Ni/Zn hydroxy double salts. The Ni/Zn ratio could be varied from 1.2 to 1.9 by varying the metal contents of the precursor salts without the formation of any impurities in the sample. The prepared compounds had similar characteristics as that of the samples prepared by precipitation route. No sign of carbonate contamination was observed in any of the prepared samples.

  8. Prebiotic Synthesis of Diaminopyrimidine and Thiocytosine

    NASA Technical Reports Server (NTRS)

    Robertson, Michael P.; Levy, Matthew; Miller, Stanley L.

    1996-01-01

    The reaction of guanidine hydrochloride with cyanoacetaldehyde gives high yields (40-85%) of 2,4-diaminopyrimidine under the concentrated conditions of a drying lagoon model of prebiotic synthesis, in contrast to the low yields previously obtained under more dilute conditions. The prebiotic source of cyanoacetaldehyde, cyanoacetylene, is produced from electric discharges under reducing conditions. The effect of pH and concentration of guanidine hydrochloride on the rate of synthesis and yield of diaminopyrimidine were investigated, as well as the hydrolysis of diaminopyrimidine to cytosine, isocytosine, and uracil. Thiourea also reacts with cyanoacetaldehyde to give 2-thiocytosine, but the pyrimidine yields are much lower than with guanidine hydrochloride or urea. Thiocytosine hydrolyzes to thiouracil and cytosine and then to uracil. This synthesis would have been a significant prebiotic source of 2-thiopyrimidines and 5-substituted derivatives of thiouracil, many of which occur in tRNA. The applicability of these results to the drying lagoon model of prebiotic synthesis was tested by dry-down experiments where dilute solutions of cyanoacetaldehyde, guanidine hydrochloride, and 0.5 M NaCl were evaporated over varying periods of time. The yields of diaminopyrimidine varied from 1 to 7%. These results show that drying lagoons and beaches may have been major sites of prebiotic syntheses.

  9. Carbohydrate-Based Lactones: Synthesis and Applications

    NASA Astrophysics Data System (ADS)

    Xavier, Nuno M.; Rauter, Amélia P.; Queneau, Yves

    The synthesis and uses of different kinds of carbohydrate-based lactones are described. This group of compounds includes aldonolactones, other related monocyclic lactones and bicyclic systems. The latter can arise from uronic acids, carboxymethyl ethers or glycosides, or from C-branched sugars.

  10. Synthesis of RNA oligomers on heterogeneous templates

    NASA Technical Reports Server (NTRS)

    Ertem, G.; Ferris, J. P.

    1996-01-01

    The concept of an RNA world in the chemical origin of life is appealing, as nucleic acids are capable of both information storage and acting as templates that catalyse the synthesis of complementary molecules. Template-directed synthesis has been demonstrated for homogeneous oligonucleotides that, like natural nucleic acids, have 3',5' linkages between the nucleotide monomers. But it seems likely that prebiotic routes to RNA-like molecules would have produced heterogeneous molecules with various kinds of phosphodiester linkages and both linear and cyclic nucleotide chains. Here we show that such heterogeneity need be no obstacle to the templating of complementary molecules. Specifically, we show that heterogeneous oligocytidylates, formed by the montmorillonite clay-catalysed condensation of actuated monomers, can serve as templates for the synthesis of oligoguanylates. Furthermore, we show that oligocytidylates that are exclusively 2',5'-linked can also direct synthesis of oligoguanylates. Such heterogeneous templating reactions could have increased the diversity of the pool of protonucleic acids from which life ultimately emerged.

  11. Vitamins and aging: pathways to NAD+ synthesis.

    PubMed

    Denu, John M

    2007-05-04

    Recent genetic evidence reveals additional salvage pathways for NAD(+) synthesis. In this issue, Belenky et al. (2007) report that nicotinamide riboside, a new NAD(+) precursor, regulates Sir2 deacetylase activity and life span in yeast. The ability of nicotinamide riboside to enhance life span does not depend on calorie restriction.

  12. Sol-Gel Synthesis Of Aluminoborosilicate Powders

    NASA Technical Reports Server (NTRS)

    Bull, Jeffrey; Leiser, Daniel; Selvaduray, Guna

    1992-01-01

    Application of sol-gel process to synthesis of aluminoborosilicate powders shows potential for control of microstructures of materials. Development of materials having enhanced processing characteristics prove advantageous in extending high-temperature endurance of fibrous refractory composite insulation made from ceramic fibers.

  13. A synthesis array for lunar submillimeter astronomy

    NASA Technical Reports Server (NTRS)

    Mahoney, M. J.

    1990-01-01

    This paper describes a system concept for a synthesis array for lunar submillimeter astronomy (SALSA). It includes a brief discussion of the science objectives and the advantages of a placing such an array on the moon, the system concept, and a top-level discussion of the various subsystems, including the technology drivers associated with each.

  14. Synthesis and enantiomeric resolution of (+/-)-pinocembrin.

    PubMed

    Yuan, Yue; Yang, Qing-Yun; Tong, Yuan-Feng; Chen, Feng; Qi, Yan; Duan, Ya-Bo; Wu, Song

    2008-01-01

    A convenient method for the synthesis and enantiomeric resolution of ( +/- )-pinocembrin has been developed. This route involves the hydrogenation of 5,7-dihydroxyflavone, the derivatization of racemic pinocembrin with chiral amine, and the separation of the diastereoisomers due to their different physical properties.

  15. Divergent Synthesis of Heparan Sulfate Oligosaccharides

    PubMed Central

    2015-01-01

    Heparan sulfates are implicated in a wide range of biological processes. A major challenge in deciphering their structure and activity relationship is the synthetic difficulties to access diverse heparan sulfate oligosaccharides with well-defined sulfation patterns. In order to expedite the synthesis, a divergent synthetic strategy was developed. By integrating chemical synthesis and two types of O-sulfo transferases, seven different hexasaccharides were obtained from a single hexasaccharide precursor. This approach combined the flexibility of chemical synthesis with the selectivity of enzyme-catalyzed sulfations, thus simplifying the overall synthetic operations. In an attempt to establish structure activity relationships of heparan sulfate binding with its receptor, the synthesized oligosaccharides were incorporated onto a glycan microarray, and their bindings with a growth factor FGF-2 were examined. The unique combination of chemical and enzymatic approaches expanded the capability of oligosaccharide synthesis. In addition, the well-defined heparan sulfate structures helped shine light on the fine substrate specificities of biosynthetic enzymes and confirm the potential sequence of enzymatic reactions in biosynthesis. PMID:26574650

  16. Leader Succession and Socialization: A Synthesis.

    ERIC Educational Resources Information Center

    Hart, Ann Weaver

    1991-01-01

    Leader-succession research is refocused on its interactive roots whereas the advances of recent succession inquiry are explored in this synthesis of the literature. The approach capitalizes on efforts to understand leader-succession research from a multidimensional and social viewpoint. Organizational socialization is used to frame the discussion.…

  17. A Synthesis-Oriented VHDL Course

    ERIC Educational Resources Information Center

    d'Amore, Roberto

    2010-01-01

    This article proposes a VHDL language course that establishes a strong correlation between the language statements and their use in circuit synthesis. Two course modules are described: a basic module that contains the essential concepts of the language, sufficient for students to describe medium complexity circuits, followed by a second module…

  18. Synthesis and tribological investigation of lipoyl glycerides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lipoyl glycerides (LG) were synthesized by enzymatic transesterification of lipoic acid (LA) with high oleic sunflower oil (HOSuO) in 2-methyl-2-butanol solvent. The synthesis gave a crude product mixture (LGc) comprising unreacted LA, free fatty acids (FFA), and various LG structures with varying d...

  19. Formal Synthesis of (±)-Roseophilin

    PubMed Central

    Bitar, Abdallah Y.; Frontier, Alison J.

    2009-01-01

    A formal synthesis of (±)-roseophilin is described. Scandium(III)-catalyzed Nazarov cyclization of 2,5-disubstituted N-tosylpyrrole 19 gives a 5,5’-fused ketopyrrole, and ansa-bridge formation via π-allyl palladium macrocyclization gives 21. PMID:19053717

  20. Synthesis of aryl halides via organoborane chemistry

    SciTech Connect

    Kabalka, G.W.; Sastry, K.A.R.; Sastry, U.; Somayaji, V.

    1982-01-01

    A method for the rapid synthesis of a variety of substituted aryl halides by the reaction of organoboranes with halide ions in the presence of chloramine-T is described in detail. The products were purified by column chromatography on silica gel using a mixture of petroleum ether-ethyl acetate as eluent.

  1. Total synthesis of zincophorin methyl ester.

    PubMed

    Defosseux, Magali; Blanchard, Nicolas; Meyer, Christophe; Cossy, Janine

    2003-10-30

    [reaction: see text]. A convergent total synthesis of the methyl ester of zincophorin, an ionophore antibiotic, has been realized relying on a diastereoselective titanium-mediated aldol coupling between the C1-C12 and C13-C25 subunits. The latter fragment was prepared by using a Carroll-Claisen rearrangement.

  2. An extended synthesis for evolutionary biology.

    PubMed

    Pigliucci, Massimo

    2009-06-01

    Evolutionary theory is undergoing an intense period of discussion and reevaluation. This, contrary to the misleading claims of creationists and other pseudoscientists, is no harbinger of a crisis but rather the opposite: the field is expanding dramatically in terms of both empirical discoveries and new ideas. In this essay I briefly trace the conceptual history of evolutionary theory from Darwinism to neo-Darwinism, and from the Modern Synthesis to what I refer to as the Extended Synthesis, a more inclusive conceptual framework containing among others evo-devo, an expanded theory of heredity, elements of complexity theory, ideas about evolvability, and a reevaluation of levels of selection. I argue that evolutionary biology has never seen a paradigm shift, in the philosophical sense of the term, except when it moved from natural theology to empirical science in the middle of the 19th century. The Extended Synthesis, accordingly, is an expansion of the Modern Synthesis of the 1930s and 1940s, and one that--like its predecessor--will probably take decades to complete.

  3. Evaluation Synthesis for the Legislative User.

    ERIC Educational Resources Information Center

    Chelimsky, Eleanor; Morra, Linda G.

    1984-01-01

    Evaluation synthesis, a meta-evaluation method developed by the General Accounting Office to improve evaluation utilization by legislators, is described. It is designed to: (1) focus on the information needs and priorities of legislators, and (2) ensure continuous communication between sponsor and evaluator. The strengths and limitations of this…

  4. Synthesis and Crystallization Behavior of Fluoride Glasses

    DTIC Science & Technology

    1989-08-22

    metal fluoride glasses. Exploration of synthesis conditions for converting precursors to multicomponent oxide gels for conversion to heavy metal fluoride...glasses. Exploration of chemistries and conditions for converting multicomponent oxide gels to heavy metal fluoride glasses. Exploration of...chemical approaches to passivating the surfaces of heavy metal fluoride glasses. Exploration of the possibility of developing a computer model to describe

  5. Enantioselective synthesis of (+)-royleanone from sulfinyl quinones.

    PubMed

    Carreño, M C; García Ruano, J L; Toledo, M A

    2000-01-01

    A convergent enantioselective synthesis of (+)-royleanone (1) is described starting from enantiomerically pure (S)-3-hydroxy-2-isopropyl-5-tert-butylsulfinyl-p-benzoquinone, which is readily available from 3-isopropyl-1,2,4-trimethoxybenzene and 1,3,3-trimethyl-2-vinylcyclohexene. The key step is a tandem asymmetric Diels-Alder reaction/pyrolytic sulfoxide elimination process.

  6. Synthesis of an integrated cockpit management system

    NASA Technical Reports Server (NTRS)

    Dasaro, J. A.; Elliott, C. T.

    1982-01-01

    The process used in the synthesis of an integrated cockpit management system was discussed. Areas covered included flight displays, subsystem management, checklists, and procedures (both normal and emergency). The process of evolving from the unintegrated conventional system to the integrated system is examined and a brief description of the results presented.

  7. Enantioselective Synthesis of Strobamine and its Analogues

    DTIC Science & Technology

    2010-01-01

    using likelihood methods in PLATON .6,7 Based on the analysis of 1077 Bijvoet pairs (90% coverage), this analysis indicated that the absolute structure...Majewski, M.; Lazny, R. J. Org. Chem. 1995, 60, 5825. 5. Olah, G. A.; Arvanaghi, M.; Prakash, G. K. S. Synthesis 1983, 636. 6. Spek, A. L. PLATON

  8. Green Synthesis of Nanomaterials: Environmental Aspects

    EPA Science Inventory

    There is always a search for reliable and environmentally friendly processes to manufacture metal and metal oxide nanoparticles minimizing or even eliminating the use of hazardous chemicals. The only way to develop these “green” processes is to adapt benign synthesis approaches t...

  9. Honey mediated green synthesis of gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Philip, Daizy

    2009-08-01

    Bio-directed synthesis of nanoparticles is of interest to biologists, chemists and materials scientists alike, especially in light of efforts to find greener methods of inorganic material synthesis. Though the biosynthesis of gold nanoparticles has been carried out by several groups of scientists using plants, fungi and bacteria, so far there is no report on the use of natural honey - mankind's only sweetener for centuries - for the synthesis of nanoparticles. Here, it is a report on a greener synthesis of Au nanoparticles using honey as reducing and capping agents. By adjusting the concentrations of HAuCl 4 and honey in aqueous solutions, colloids having a larger propensity of either anisotropic or spherical nanocrystals could be obtained at room temperature. The nanoparticles obtained were characterized by UV-visible spectra, high-resolution TEM and XRD. The spherical particles obtained have a size ˜15 nm as shown by XRD pattern and TEM image. The high crystallinity with fcc phase is evidenced by bright circular spots in SAED pattern and clear lattice fringes in the high-resolution TEM image. FTIR measurements were carried out to identify the possible biomolecules responsible for capping and efficient stabilization of the Au nanoparticles synthesized using honey. The carboxylic acid group vibrations and amide I and II bands indicate the binding of protein with Au surface through the amine group rather than the carboxyl group.

  10. Phylogenomic investigation of phospholipid synthesis in archaea.

    PubMed

    Lombard, Jonathan; López-García, Purificación; Moreira, David

    2012-01-01

    Archaea have idiosyncratic cell membranes usually based on phospholipids containing glycerol-1-phosphate linked by ether bonds to isoprenoid lateral chains. Since these phospholipids strongly differ from those of bacteria and eukaryotes, the origin of the archaeal membranes (and by extension, of all cellular membranes) was enigmatic and called for accurate evolutionary studies. In this paper we review some recent phylogenomic studies that have revealed a modified mevalonate pathway for the synthesis of isoprenoid precursors in archaea and suggested that this domain uses an atypical pathway of synthesis of fatty acids devoid of any acyl carrier protein, which is essential for this activity in bacteria and eukaryotes. In addition, we show new or updated phylogenetic analyses of enzymes likely responsible for the isoprenoid chain synthesis from their precursors and the phospholipid synthesis from glycerol phosphate, isoprenoids, and polar head groups. These results support that most of these enzymes can be traced back to the last archaeal common ancestor and, in many cases, even to the last common ancestor of all living organisms.

  11. A Computer Program for Organic Synthesis.

    ERIC Educational Resources Information Center

    Long, Alan K.; And Others

    1983-01-01

    The current organic synthesis program at Harvard University is called the Logic and Heuristics Applied to Synthetic Analysis (LHASA). Discusses this program in detail, focusing on retrosynthetic analysis approach, LHASA hardware, graphical input/perception, strategy control, transform evaluation, and LHASA enhancement. (JN)

  12. Azodicarboxylates: synthesis and functionalization of organic compounds

    NASA Astrophysics Data System (ADS)

    Zhirov, A. M.; Aksenov, A. V.

    2014-06-01

    The data on transformations of dialkyl azodicarboxylates and their analogues involving various substrates are generalized. Nucleophilic addition and oxidation, pericyclic reactions and reactions occurring under the Mitsunobu reaction conditions are considered. Ample opportunities for application of these compounds in fine organic synthesis are shown. The bibliography includes 245 references. Dedicated to Academician B A Trofimov on the occasion of his 75th birthday.

  13. Computer-Assisted Instruction in Organic Synthesis.

    ERIC Educational Resources Information Center

    Snieckus, V.

    Using the Corey approach, retrosynthetic/synthetic schemes for six organic molecules of increasing complexity were programmed and tested in a module designed for a fourth year undergraduate course. A portion of a simple synthesis is presented and analyzed. Problems encountered were discussed and potential solutions are proposed. The module was…

  14. Synthesis of proposed aglycone of mandelalide A.

    PubMed

    Reddy, Karla Mahender; Yamini, Vanipenta; Singarapu, Kiran K; Ghosh, Subhash

    2014-05-16

    A highly convergent synthesis of the proposed mandelalide A aglycone is reported. The cornerstones of the synthetic strategy include the following: E-selective intramolecular Heck cyclization, Masamune-Roush olefination, Stork-Zhao-Wittig olefination, modified Prins cyclization; Sharpless asymmetric dihydroxylation followed by Williamson-type etherification, Julia-Kocienski olefination, Brown crotylation, and Brown allylation reactions.

  15. Synthesis of an algorithm for interference immunity

    NASA Astrophysics Data System (ADS)

    Kartsan, I. N.; Tyapkin, V. N.; Dmitriev, D. D.; Goncharov, A. E.; Zelenkov, P. V.; Kovalev, I. V.

    2016-11-01

    This paper discusses the synthesis of an algorithm for adaptive interference nulling of an 8-element phased antenna array. An adaptive beamforming system has been built on the basis of the algorithm. The paper discusses results of experimental functioning of navigation satellite systems user equipment fitted with an adaptive phased antenna array in interference environments.

  16. An Easy Synthesis of Two Cage Hydrocarbons.

    ERIC Educational Resources Information Center

    Dong, Dao Cong

    1982-01-01

    Describes a simple, three-step synthesis of two cage molecules, birdcage hydrocarbon (VIII) and its homologue, the homobirdcage hydrocarbon IX. Indicates that all products are easily purified and formed in high yields in this activity suitable for advanced undergraduate laboratory courses. (Author/JN)

  17. Effective Practices for Spelling Instruction: Literature Synthesis.

    ERIC Educational Resources Information Center

    Cotton, Kathleen

    Because identification of effective instructional practices for building spelling skills remains a concern of those charged with guiding the development of student language arts competencies, this paper presents a synthesis of research and expert opinion on those practices that have been shown to foster spelling proficiency among both beginning…

  18. Stereoselective Synthesis of Quaternary Proline Analogues

    PubMed Central

    Calaza, M. Isabel

    2009-01-01

    This review describes available methods for the diastereoselective and asymmetric synthesis of quaternary prolines. The focus is on the preparation of α-functionalized prolines with the pyrrolidine moiety not embedded in a polycyclic frame. The diverse synthetic approaches are classified according to the bond which is formed to complete the quaternary skeleton. PMID:19655047

  19. Continuous and Discontinuous RNA Synthesis in Coronaviruses.

    PubMed

    Sola, Isabel; Almazán, Fernando; Zúñiga, Sonia; Enjuanes, Luis

    2015-11-01

    Replication of the coronavirus genome requires continuous RNA synthesis, whereas transcription is a discontinuous process unique among RNA viruses. Transcription includes a template switch during the synthesis of subgenomic negative-strand RNAs to add a copy of the leader sequence. Coronavirus transcription is regulated by multiple factors, including the extent of base-pairing between transcription-regulating sequences of positive and negative polarity, viral and cell protein-RNA binding, and high-order RNA-RNA interactions. Coronavirus RNA synthesis is performed by a replication-transcription complex that includes viral and cell proteins that recognize cis-acting RNA elements mainly located in the highly structured 5' and 3' untranslated regions. In addition to many viral nonstructural proteins, the presence of cell nuclear proteins and the viral nucleocapsid protein increases virus amplification efficacy. Coronavirus RNA synthesis is connected with the formation of double-membrane vesicles and convoluted membranes. Coronaviruses encode proofreading machinery, unique in the RNA virus world, to ensure the maintenance of their large genome size.

  20. Learning Paths in Academic Setting: Research Synthesis

    ERIC Educational Resources Information Center

    Mirkov, Snežana

    2013-01-01

    The paper represents a synthesis of results obtained in empirical studies of variables related to learning process. A number of studies were carried out within the Students Approaches to Learning perspective. According to the 3P model of learning, the complex of learning process comprises three learning approaches--Deep, Surface and Achievement…

  1. Protein synthesis in geostimulated root caps

    NASA Technical Reports Server (NTRS)

    Feldman, L. J.

    1982-01-01

    A study is presented of the processes occurring in the root cap of corn which are requisite for the formation of root cap inhibitor and which can be triggered or modulated by both light and gravity. The results of this study indicate the importance of protein synthesis for light-induced gravitropic bending in roots. Root caps in which protein synthesis is prevented are unable to induce downward bending. This suggests that light acts by stimulating proteins which are necessary for the translation of the gravitropic stimulus into a growth response (downward bending). The turnover of protein with time was also examined in order to determine whether light acts by stimulating the synthesis of unique proteins required for downward growth. It is found that auxin in combination with light allows for the translation of the gravitropic stimulus into a growth response at least in part through the modification of protein synthesis. It is concluded that unique proteins are stimulated by light and are involved in promoting the downward growth in roots which are responding to gravity.

  2. Benzodiazepine Synthesis and Rapid Toxicity Assay

    ERIC Educational Resources Information Center

    Fletcher, James T.; Boriraj, Grit

    2010-01-01

    A second-year organic chemistry laboratory experiment to introduce students to general concepts of medicinal chemistry is described. Within a single three-hour time window, students experience the synthesis of a biologically active small molecule and the assaying of its biological toxicity. Benzodiazepine rings are commonly found in antidepressant…

  3. An efficient catalytic method for fulvene synthesis

    PubMed Central

    Coşkun, Necdet; Erden, Ihsan

    2011-01-01

    The effects of the nature and amount of base, substrate structure, amount of added water and solvent on the condensation of carbonyl compounds with cyclopentadiene in the presence of secondary amines were investigated. Based on these studies, a new efficient and green synthesis of fulvenes was developed. PMID:22021940

  4. Synthesis of pterostilbene by Julie Olefination

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A simple, stereoselective route for the synthesis of the biologically active compounds trans-pterostilbene and tetramethoxy stilbene from the readily available starting materials 3,5-dimethoxy benzyl alcohol and 4-hydroxy benzaldehyde was developed using Julia olefination as a key reaction....

  5. Enantioselective Synthesis of Cephalimysins B and C.

    PubMed

    Chalupa, David; Vojáčková, Petra; Partl, Jiří; Pavlović, Dražen; Nečas, Marek; Švenda, Jakub

    2017-02-17

    The first synthesis of cephalimysins B and C is reported. The route features a Ni(II)-diamine-catalyzed enantioselective conjugate addition of a densely substituted 3(2H)-furanone and an efficient dihydroxylation-lactonization sequence as key steps in the assembly of the spirocyclic core. The fully synthetic strategy is amenable to analog preparation.

  6. Synthesis Road Map Problems in Organic Chemistry

    ERIC Educational Resources Information Center

    Schaller, Chris P.; Graham, Kate J.; Jones, T. Nicholas

    2014-01-01

    Road map problems ask students to integrate their knowledge of organic reactions with pattern recognition skills to "fill in the blanks" in the synthesis of an organic compound. Students are asked to identify familiar organic reactions in unfamiliar contexts. A practical context, such as a medicinally useful target compound, helps…

  7. A property of subspaces admitting spectral synthesis

    SciTech Connect

    Abuzyarova, N F

    1999-04-30

    Let H be the space of holomorphic functions in a convex domain G subset of C. The following result is established: each closed subspace W subset of H that is invariant with respect to the operator of differentiation and admits spectral synthesis can be represented as the solution set of two (possibly coinciding) homogeneous convolution equations.

  8. Teaching Research Synthesis to Advanced Practice Nurses.

    ERIC Educational Resources Information Center

    Upchurch, Sandra; Brosnan, Christine A.; Grimes, Deanna E.

    2002-01-01

    A process for teaching research synthesis to advanced practice nurses includes two courses: a first research applications course in which students build bibliographic databases, practice statistical analysis, and develop search skills; and a second course in which they complete literature reviews or meta analyses of research on clinical practice…

  9. Magnetically retrievable catalysts for organic synthesis

    EPA Science Inventory

    The use of magnetic nanoparticles (MNPs) as a catalyst in organic synthesis has become a subject of intense investigation. The recovery of expensive catalysts after catalytic reaction and reusing it without losing its activity is an important feature in the sustainable process de...

  10. A reliable algorithm for optimal control synthesis

    NASA Technical Reports Server (NTRS)

    Vansteenwyk, Brett; Ly, Uy-Loi

    1992-01-01

    In recent years, powerful design tools for linear time-invariant multivariable control systems have been developed based on direct parameter optimization. In this report, an algorithm for reliable optimal control synthesis using parameter optimization is presented. Specifically, a robust numerical algorithm is developed for the evaluation of the H(sup 2)-like cost functional and its gradients with respect to the controller design parameters. The method is specifically designed to handle defective degenerate systems and is based on the well-known Pade series approximation of the matrix exponential. Numerical test problems in control synthesis for simple mechanical systems and for a flexible structure with densely packed modes illustrate positively the reliability of this method when compared to a method based on diagonalization. Several types of cost functions have been considered: a cost function for robust control consisting of a linear combination of quadratic objectives for deterministic and random disturbances, and one representing an upper bound on the quadratic objective for worst case initial conditions. Finally, a framework for multivariable control synthesis has been developed combining the concept of closed-loop transfer recovery with numerical parameter optimization. The procedure enables designers to synthesize not only observer-based controllers but also controllers of arbitrary order and structure. Numerical design solutions rely heavily on the robust algorithm due to the high order of the synthesis model and the presence of near-overlapping modes. The design approach is successfully applied to the design of a high-bandwidth control system for a rotorcraft.

  11. High Pressure Synthesis of Transition Metal Carbonyls.

    ERIC Educational Resources Information Center

    Hagen, A. P.; And Others

    1979-01-01

    Presents an experiment which uses readily available starting materials and inexpensive equipment for synthesis of transition metal carbonyls at 1000 atm and which is intended to give students experience in techniques used in research and industry. Safety precautions are emphasized. (Author/SA)

  12. First Synthesis of the Antiangiogenic Homoisoflavanone, Cremastranone

    PubMed Central

    Lee, Bit; Basavarajappa, Halesha D.; Sulaiman, Rania S.; Fei, Xiang; Seo, Seung-Yong; Corson, Timothy W.

    2014-01-01

    An antiangiogenic homoisoflavanone, cremastranone, was synthesized for the first time. This scalable synthesis, which includes selective demethylation, could be used to develop lead molecules to treat angiogenesis-induced eye diseases. Synthetic cremastranone inhibited the proliferation, migration and tube formation ability of human retinal microvascular endothelial cells, important steps in pathological angiogenesis. PMID:25167470

  13. Biological conversion of synthesis gas culture development

    SciTech Connect

    Klasson, K.T.; Basu, R.; Johnson, E.R.; Clausen, E.C.; Gaddy, J.L.

    1992-03-01

    Research continues on the conversion of synthesis by shift reactions involving bacteria. Topics discussed here include: biological water gas shift, sulfur gas utilization, experimental screening procedures, water gas shift studies, H{sub 2}S removal studies, COS degradation by selected CO-utilizing bacteria, and indirect COS utilization by Chlorobia. (VC)

  14. Synthesis of the Commercial Antidepressant Moclobemide

    ERIC Educational Resources Information Center

    More, Jesse D.

    2008-01-01

    An experiment for the undergraduate organic chemistry laboratory is described in which students synthesize the commercial antidepressant drug moclobemide, marketed under the trade name Manerix. This one-step synthesis starts from commercially available material and produces moclobemide in high yield. The product is initially isolated as its…

  15. Microwave Assisted Synthesis of Biorelevant Benzazoles.

    PubMed

    Seth, Kapileswar; Purohit, Priyank; Chakraborti, Asit K

    2016-10-25

    The benzazole scaffolds are present in various therapeutic agents and have been recognized as the essential pharmacophore for diverse biological activities. These have generated interest and necessity to develop efficient synthetic methods of these privileged classes of compounds to generate new therapeutic leads for various diseases. The biological activities of the benzazoles and efforts towards their synthesis have been summarized in a few review articles. In view of these, the aim of this review is to provide an account of the developments that have taken place in the synthesis of biorelevant benzazoles under microwave irradiation as the application of microwave heating has long been recognized as a green chemistry tool for speedy generation of synthetic targets. Attention has been focused to those literature reports wherein the use of microwave irradiation is the key step in the formation of the heterocyclic ring system or in functionalization of the benzazole ring system to generate the essential pharmacophoric feature. The convenient and economic way to synthesize these privileged class of heterocycles through the use of microwave irradiation that would be beneficial for the drug discovery scientist to synthesize biologically active benzazoles and provide access to wide range of reactions for the synthesis of benzazoles constitute the theme of this review. Examples have been drawn wherein the use of microwave heating offers distinct advantage in terms of improved product yields and reduction of reaction time as compared to those observed for the synthesis under conventional heating.

  16. STEM Education in Canada: A Knowledge Synthesis

    ERIC Educational Resources Information Center

    DeCoito, Isha

    2016-01-01

    Across Canada many initiatives have been initiated to generate more interest in science, technology, engineering, and mathematics (STEM) education; however, no single or comprehensive overview has been conducted that takes into account the impact of these STEM initiatives on teaching/learning outcomes in K-12 education. This knowledge synthesis of…

  17. Plastidic Isoprenoid Synthesis during Chloroplast Development 1

    PubMed Central

    Heintze, Adolf; Görlach, Jörn; Leuschner, Carola; Hoppe, Petra; Hagelstein, Petra; Schulze-Siebert, Detlef; Schultz, Gernot

    1990-01-01

    The chloroplast isoprenoid synthesis of very young leaves is supplied by the plastidic CO2 → pyruvate → acetyl-coenzyme A (C3 → C2) metabolism (D Schulze-Siebert, G Schultz [1987] Plant Physiol 84: 1233-1237) and occurs via the plastidic mevalonate pathway. The plastidic C3 → C2 metabolism and/or plastidic mevalonate pathway of barley (Hordeum vulgare L.) seedlings changes from maximal activity at the leaf base (containing developing chloroplasts with incomplete thylakoid stacking but a considerable rate of photosynthetic CO2-fixation) almost to ineffectivity at the leaf tip (containing mature chloroplasts with maximal photosynthetic activity). The ability to import isopentenyl diphosphate from the extraplastidic space gradually increases to substitute for the loss of endogenous intermediate supply for chloroplast isoprenoid synthesis (change from autonomic to division-of-labor stage). Fatty acid synthesis from NaH14CO3 decreases in the same manner as shown for leaf sections and chloroplasts isolated from these. Evidence has been obtained for a drastic decrease of pyruvate decarboxylase-dehydrogenase activity during chloroplast development compared with other anabolic chloroplast pathways (synthesis of aromatic amino acid and branched chain amino acids). The noncompetition of pyruvate and acetate in isotopic dilution studies indicates that both a pyruvate-derived and an acetate-derived compound are simultaneously needed to form introductory intermediates of the mevalonate pathway, presumably acetoacetyl-coenzyme A. PMID:16667567

  18. Synthesis and testing of nanosized zeolite Y

    NASA Astrophysics Data System (ADS)

    Karami, Davood

    This work focuses on the synthesis and testing of nanosized zeolite Y. The synthesis formulations of faujasite-type structure of zeolite Y prepared in nanosized form are described. The synthetic zeolite Y is the most widely employed for the preparation of fluid catalytic cracking (FCC) catalysts. The synthesis of zeolite Y is very complicated process. The mean particle size of zeolite Y is 1800 nm. The major challenge of this work involved reducing this average particle size to less than 500 nm. The preliminary experiments were conducted to obtain the pure zeolite Y using the soluble silicates as a silica source. This was achieved by applying the experimental design approach to study the effects of many parameters. The ageing time turned out to be the most significant variable affecting product purity. Based on the preliminary results, a detailed investigation was carried out to determine the effects of silica-alumina precursor preparations on zeolite Y synthesis. Aluminosilicate precursors were prepared by gelling and precipitation of soluble silicate. The as-prepared precursors were used for the hydrothermal synthesis of zeolite Y. The procedure of the precipitation of soluble silicate yielded pure zeolite Y at the conventional synthesis conditions. The extent of purity of zeolite Y depends on the surface areas of aluminosilicate precursors. A novel approach to zeolite Y synthesis was employed for the preparation of the pure nanosized zeolite Y. This was achieved by applying the method of impregnation of precipitated silica. This novel method of impregnation for zeolite Y preparation allows eliminating the vigorous agitation step required for the preparation of a homogeneous silica solution, thereby simplifying the synthesis of zeolite Y in one single vessel. In case of the synthesis of nanosized zeolite Y, the effect of varying the organic templates on the formation of nanosized particles of zeolite Y was investigated, while all other reaction parameters were

  19. Function through synthesis-informed design.

    PubMed

    Wender, Paul A; Quiroz, Ryan V; Stevens, Matthew C

    2015-03-17

    In 1996, a snapshot of the field of synthesis was provided by many of its thought leaders in a Chemical Reviews thematic issue on "Frontiers in Organic Synthesis". This Accounts of Chemical Research thematic issue on "Synthesis, Design, and Molecular Function" is intended to provide further perspective now from well into the 21st century. Much has happened in the past few decades. The targets, methods, strategies, reagents, procedures, goals, funding, practices, and practitioners of synthesis have changed, some in dramatic ways as documented in impressive contributions to this issue. However, a constant for most synthesis studies continues to be the goal of achieving function with synthetic economy. Whether in the form of new catalysts, reagents, therapeutic leads, diagnostics, drug delivery systems, imaging agents, sensors, materials, energy generation and storage systems, bioremediation strategies, or molecules that challenge old theories or test new ones, the function of a target has been and continues to be a major and compelling justification for its synthesis. While the targets of synthesis have historically been heavily represented by natural products, increasingly design, often inspired by natural structures, is providing a new source of target structures exhibiting new or natural functions and new or natural synthetic challenges. Complementing isolation and screening approaches to new target identification, design enables one to create targets de novo with an emphasis on sought-after function and synthetic innovation with step-economy. Design provides choice. It allows one to determine how close a synthesis will come to the ideal synthesis and how close a structure will come to the ideal function. In this Account, we address studies in our laboratory on function-oriented synthesis (FOS), a strategy to achieve function by design and with synthetic economy. By starting with function rather than structure, FOS places an initial emphasis on target design

  20. Software Synthesis for High Productivity Exascale Computing

    SciTech Connect

    Bodik, Rastislav

    2010-09-01

    Over the three years of our project, we accomplished three key milestones: We demonstrated how ideas from generative programming and software synthesis can help support the development of bulk-synchronous distributed memory kernels. These ideas are realized in a new language called MSL, a C-like language that combines synthesis features with high level notations for array manipulation and bulk-synchronous parallelism to simplify the semantic analysis required for synthesis. We also demonstrated that these high level notations map easily to low level C code and show that the performance of this generated code matches that of handwritten Fortran. Second, we introduced the idea of solver-aided domain-specific languages (SDSLs), which are an emerging class of computer-aided programming systems. SDSLs ease the construction of programs by automating tasks such as verification, debugging, synthesis, and non-deterministic execution. SDSLs are implemented by translating the DSL program into logical constraints. Next, we developed a symbolic virtual machine called Rosette, which simplifies the construction of such SDSLs and their compilers. We have used Rosette to build SynthCL, a subset of OpenCL that supports synthesis. Third, we developed novel numeric algorithms that move as little data as possible, either between levels of a memory hierarchy or between parallel processors over a network. We achieved progress in three aspects of this problem. First we determined lower bounds on communication. Second, we compared these lower bounds to widely used versions of these algorithms, and noted that these widely used algorithms usually communicate asymptotically more than is necessary. Third, we identified or invented new algorithms for most linear algebra problems that do attain these lower bounds, and demonstrated large speed-ups in theory and practice.

  1. Liver collagen synthesis in murine schistosomiasis.

    PubMed Central

    Dunn, M A; Rojkind, M; Warren, K S; Hait, P K; Rifas, L; Seifter, S

    1977-01-01

    Collagen synthesis was measured in liver slices obtained from mice with hepatosplenic schistosomiasis. Enlarged fibrotic livers from these mice contained 20 times more collagen than normal. This model of hepatic fibrosis results from an inflammatory granulomatous host response to Schistosoma mansoni ova in portal tracts, rather than from direct lover cell injury as with carbon tetrachloride-induced liver fibrosis. Collagen synthesis, as measured by the formation of labeled protein-bound hydroxyproline, occurred in granulomas isolated from fibrotic livers. Labeled collagen that cochromatographed with type I collagen was extracted with neutral salt solution from liver slices incubated with labeled proline. The free proline pool of the liver was doubled in infected mice; coordinately, liver slices from these animals showed maximal collagen production when the concentration of free proline in the medium was raised to 0.4 mM, the same level measured in the fibrotic livers. Under such conditions, collagen synthesis was at a rate equivalent to the formation of 5.4 nmol of protein-bound hydroxyproline per g liver in 6 h. In comparative incubations in medium containing 0.2 mM proline, fibrotic liver slices produced 16-fold more collagen than normal slices. The proline analogue, L-azetidine 2-carboxylic acid, effectively inhibited synthesis of labeled collagen by fibrotic liver slices. These studies show the synthesis of collagen in a reproducible animal model of the most prevalent form of human liver fibrosis. Difinitition of the controlling factors in this system is of interest for the general problem of fibrosis produced by immunological responses. Images PMID:845255

  2. SYNTHESIS OF RIBONUCLEIC ACID BY X-IRRADIATED BACTERIA1

    PubMed Central

    Frampton, E. W.

    1964-01-01

    Frampton, E. W. (The University of Texas M. D. Anderson Hospital and Tumor Institute, Houston). Synthesis of ribonucleic acid by X-irradiated bacteria. J. Bacteriol. 87:1369–1376. 1964.—Postirradiation synthesis of total ribonucleic acid (RNA) and of RNA components was measured after exposure of Escherichia coli B/r to X rays. Net synthesis of RNA measured by the orcinol reaction and by the incorporation of uridine-2-C14 was depressed in irradiated cells, but paralleled the period of postirradiation growth (30 to 40 min). Incorporation of uridine-2-C14, added after net synthesis of RNA had ceased, detected an apparent turnover in a portion of the RNA. Irradiated cells retained their ability to adjust RNA synthesis to growth rate. After a shift-down in growth rate, irradiated cells incorporated radioactive uridine, while the net synthesis of RNA ceased—presumptive evidence for a continued synthesis of messenger RNA. Chloramphenicol addition (100 μg/ml) did not influence the total amount of RNA synthesized. Synthesis of ribosomes and transfer RNA preceded by 0, 5, 10, and 15 min of postirradiation incubation was observed by the resolution of cell-free extracts on sucrose density gradients. Little immediate influence of irradiation could be detected on the synthesis of 50S and 30S ribosomes. A decline was observed in the synthesis of 50S ribosomes with continued postirradiation incubation; 30S ribosomes, ribosomal precursors, and 4S RNA continued to be synthesized. PMID:14188715

  3. ATP Synthesis in the Extremely Halophilic Bacteria

    NASA Technical Reports Server (NTRS)

    Hochstein, Lawrence I.; Morrison, David (Technical Monitor)

    1994-01-01

    The proton-translocating ATPases are multimeric enzymes that carry out a multitude of essential functions. Their origin and evolution represent a seminal event in the early evolution of life. Amino acid sequences of the two largest subunits from archaeal ATPases (A-ATPases), vacuolar ATPases (V-ATPases), and FOF1-ATP syntheses (FATPases) suggest these ATPases evolved from an ancestral vacuolar-like ATP syntheses. A necessary consequence of this notion is that the A-ATPases are ATP syntheses. With the possible exception of the A-ATPase from Halobacterium salinarium. no A-ATPase has been demonstrated to synthesize ATP. The evidence for this case is dubious since ATP synthesis occurs only when conditions are distinctively unphysiological. We demonstrated that ATP synthesis in H.saccharovorum is inconsistent with the operation of an A-type ATPase. In order to determine if this phenomenon was unique to H. saccharovorum, ATP synthesis was examined in various extremely halophilic bacteria with the goal of ascertaining if it resembled what occurred in a. saccharovorum, or was consistent with the operation of an A-type ATPase. A-, V-, and F-type ATPases respond singularly to certain inhibitors. Therefore, the effect of these inhibitors on ATP synthesis in several extreme halophiles was determined. Inhibitors that either blocked or collapsed proton-gradients inhibited the steady state synthesis of ATP thus verifying that synthesis took place at the expense of a proton gradient. Azide, an inhibitor of F-ATPases inhibited ATP synthesis. Since the arginine-dependent synthesis of ATP, which occurs by way of substrate-level phosphorylation, was unaffected by azide, it was unlikely that azide acted as an "uncoupler." N -ethylmaleimide and nitrate, which inhibit V- and A-ATPases, either did not inhibit ATP synthesis or resulted in higher steady-state levels of ATP. These results suggest there are two types of proton-motive ATPases in the extreme halophiles (and presumably in other

  4. The Interpretation of Cholesterol Balance Derived Synthesis Data and Surrogate Noncholesterol Plasma Markers for Cholesterol Synthesis under Lipid Lowering Therapies

    PubMed Central

    Stellaard, Frans

    2017-01-01

    The cholesterol balance procedure allows the calculation of cholesterol synthesis based on the assumption that loss of endogenous cholesterol via fecal excretion and bile acid synthesis is compensated by de novo synthesis. Under ezetimibe therapy hepatic cholesterol is diminished which can be compensated by hepatic de novo synthesis and hepatic extraction of plasma cholesterol. The plasma lathosterol concentration corrected for total cholesterol concentration (R_Lath) as a marker of de novo cholesterol synthesis is increased during ezetimibe treatment but unchanged under treatment with ezetimibe and simvastatin. Cholesterol balance derived synthesis data increase during both therapies. We hypothesize the following. (1) The cholesterol balance data must be applied to the hepatobiliary cholesterol pool. (2) The calculated cholesterol synthesis value is the sum of hepatic de novo synthesis and the net plasma—liver cholesterol exchange rate. (3) The reduced rate of biliary cholesterol absorption is the major trigger for the regulation of hepatic cholesterol metabolism under ezetimibe treatment. Supportive experimental and literature data are presented that describe changes of cholesterol fluxes under ezetimibe, statin, and combined treatments in omnivores and vegans, link plasma R_Lath to liver function, and define hepatic de novo synthesis as target for regulation of synthesis. An ezetimibe dependent direct hepatic drug effect cannot be excluded. PMID:28321334

  5. Synthesis of nitrogen-substituted cycloparaphenylenes

    NASA Astrophysics Data System (ADS)

    Hirst, Elizabeth

    Bottom-up synthesis is increasingly becoming the method of choice for assembling and studying novel nanomaterials. Whereas more traditional top-down methods may lead to mixtures of products and suffer from reproducibility issues, bottom-up approaches offer atomistic control over the material's structure. Bottom-up synthesis can also produce materials that would otherwise be unobtainable with top-down methodologies. Finite substructures of carbon nanotubes (CNTs) are one such example. The work encompassed in this thesis details the study of two related classes of CNT substructures: the cycloparaphenylenes (CPPs) and [5.7]ncyclacenes. Cycloparaphenylenes are a class of graphitic material with many unique properties that make them intriguing candidates for study in a variety of electronic applications. Chapter 1 describes the current state of CPP research, from preliminary synthesis to fundamental understanding of their properties. To optimize device performance, carbon materials are often doped with heteroatoms. Towards this end, the synthesis of a series of nitrogen-doped [8]CPPs (N-[8]CPPs) are detailed in Chapter 2. Nitrogen is incorporated into the CPP structure by way of the reductive aromatization strategy used for the all carbon CPPs, replacing 1,4-dibromobenzene with 2,5-dibromopyridine. The synthesis utilizes oxidatively masked benzenes to assemble less strained, macrocyclic precursors. Through the divergent nature of the synthesis, macrocycles containing up to three nitrogen atoms at precise locations are prepared. Macrocycles are aromatized via a single electron reduction to reveal the final N-CPP structures. Chapter 3 details the full characterization of the properties of the novel N-[8]CPPs. The differences between the N-[8]CPPs and [8]CPP are rationalized in the context of DFT studies. Finally, the study of 1N-[8]CPP and [8]CPP as novel electrode materials in supercapacitor cells is presented. Preliminary results show that the CPP electrodes are more

  6. Biomimetic synthesis of noble metal nanocrystals

    NASA Astrophysics Data System (ADS)

    Chiu, Chin-Yi

    At the nanometer scale, the physical and chemical properties of materials heavily depend on their sizes and shapes. This fact has triggered considerable efforts in developing controllable nanomaterial synthesis. The controlled growth of colloidal nanocrystal is a kinetic process, in which high-energy facets grow faster and then vanish, leading to a nanocrystal enclosed by low-energy facets. Identifying a surfactant that can selectively bind to a particular crystal facet and thus lower its surface energy, is critical and challenging in shape controlled synthesis of nanocrystals. Biomolecules exhibiting exquisite molecular recognition properties can be exploited to precisely engineer nanostructured materials. In the first part of my thesis, we employed the phage display technique to select a specific multifunctional peptide sequence which can bind on Pd surface and mediate Pd crystal nucleation and growth, achieving size controlled synthesis of Pd nanocrystals in aqueous solution. We further demonstrated a rational biomimetic approach to the predictable synthesis of nanocrystals enclosed by a particular facet in the case of Pt. Specifically, Pt {100} and Pt {111} facet-specific peptides were identified and used to synthesize Pt nanocubes and Pt nano-tetrahedrons, respectively. The mechanistic studies of Pt {111} facet-specific peptide had led us to study the facet-selective adsorption of aromatic molecules on noble metal surfaces. The discoveries had achieved the development of design strategies to select facet-selective molecules which can synthesize nanocrystals with expected shapes in both Pt and Pd system. At last, we exploited Pt facet-specific peptides and controlled the molecular interaction to produce one- and three- dimensional nanostructures composed of anisotropic nanoparticles in synthetic conditions without supramolecular pre-organization, demonstrating the full potential of biomolecules in mediating material formation process. My research on biomimetic

  7. Synthesis of acrylates. Quarterly progress report, April 1, 1995--June 30, 1995

    SciTech Connect

    1995-09-05

    The objective of this research is to develop a condensation/oxidation route for the synthesis of acrylates/methacrylates from coal-derived synthesis gas. This quarter work continued on the development of catalysts for propionate synthesis.

  8. Metal-Catalyzed Asymmetric Michael Addition in Natural Product Synthesis.

    PubMed

    Hui, Chunngai; Pu, Fan; Xu, Jing

    2016-12-19

    Asymmetric catalysis for chiral compound synthesis is a rapidly growing field in modern organic chemistry. Asymmetric catalytic processes have been indispensable for the synthesis of enantioselective materials to meet demands from various fields. Michael addition has been used extensively for the construction of C-C bonds under mild conditions. With the discovery and development of organo- and metal-catalyzed asymmetric Michael additions, the synthesis of enantioselective and/or diastereoselective Michael adducts has become possible and increasingly prevalent in the literature. In particular, metal-catalyzed asymmetric Michael addition has been employed as a key reaction in natural product synthesis for the construction of contiguous quaternary stereogenic center(s), which is still a difficult task in organic synthesis. Previously reported applications of metal-catalyzed asymmetric Michael additions in natural product synthesis are presented here and discussed in depth.

  9. Microemulsions: Options To Expand the Synthesis of Inorganic Nanoparticles.

    PubMed

    Wolf, Silke; Feldmann, Claus

    2016-12-19

    Microemulsions (MEs) are ideal for obtaining high-quality inorganic nanoparticles. As thermodynamically stable systems with a nanometer-sized droplet phase that serves as a nanoreactor, MEs have obvious advantages for the synthesis of nanoparticles. MEs also have disadvantages, such as their complexity as multicomponent systems, the low amount of obtainable nanoparticles, their limited thermal stability, the fact that hydrolyzable or oxidizable compounds are often excluded from synthesis, the partly elaborate separation of nanoparticles, as well as the removal of surface-adhered surfactants subsequent to synthesis. This Review presents some strategies to further expand the options of ME-based synthesis of inorganic nanoparticles. This comprises the crystallization of nanoparticles in "high-temperature MEs", the synthesis of hollow nanospheres, the use of hydrogen peroxide or liquid ammonia as the polar droplet phase, and the synthesis of base metals and nitrides in MEs.

  10. Design, synthesis, characterization and study of novel conjugated polymers

    SciTech Connect

    Chen, Wu

    1997-06-24

    After introducing the subject of conjugated polymers, the thesis has three sections each containing a literature survey, results and discussion, conclusions, and experimental methods on the following: synthesis, characterization of electroluminescent polymers containing conjugated aryl, olefinic, thiophene and acetylenic units and their studies for use in light-emitting diodes; synthesis, characterization and study of conjugated polymers containing silole unit in the main chain; and synthesis, characterization and study of silicon-bridged and butadiene-linked polythiophenes.

  11. Brain catechol synthesis - Control by brain tyrosine concentration

    NASA Technical Reports Server (NTRS)

    Wurtman, R. J.; Larin, F.; Mostafapour, S.; Fernstrom, J. D.

    1974-01-01

    Brain catechol synthesis was estimated by measuring the rate at which brain dopa levels rose following decarboxylase inhibition. Dopa accumulation was accelerated by tyrosine administration, and decreased by treatments that lowered brain tyrosine concentrations (for example, intraperitoneal tryptophan, leucine, or parachlorophenylalanine). A low dose of phenylalanine elevated brain tyrosine without accelerating dopa synthesis. Our findings raise the possibility that nutritional and endocrine factors might influence brain catecholamine synthesis by controlling the availability of tyrosine.

  12. 3D Human Motion Editing and Synthesis: A Survey

    PubMed Central

    Wang, Xin; Chen, Qiudi; Wang, Wanliang

    2014-01-01

    The ways to compute the kinematics and dynamic quantities of human bodies in motion have been studied in many biomedical papers. This paper presents a comprehensive survey of 3D human motion editing and synthesis techniques. Firstly, four types of methods for 3D human motion synthesis are introduced and compared. Secondly, motion capture data representation, motion editing, and motion synthesis are reviewed successively. Finally, future research directions are suggested. PMID:25045395

  13. Recent progress in hydrothermal synthesis of zinc oxide nanomaterials.

    PubMed

    Djurisic, A B; Chen, X Y; Leung, Y H

    2012-06-01

    Hydrothermal synthesis is of considerable interest due to its low cost, simplicity and relatively low growth temperature (typically below 200 °C). Since the synthesis is performed in aqueous solutions (no organic solvents), it can also be safe and environmentally friendly (depending on precursor chemicals). Consequently, it has been a subject of intense research in recent years. In this article, we review recent progress in hydrothermal synthesis of zinc oxide nanomaterials, with focus on practical relevance for a variety of applications.

  14. FPGA-oriented synthesis of multivalued logical networks

    NASA Astrophysics Data System (ADS)

    Deniziak, S.; Wiśniewski, M.; Kurczyna, K.

    2016-12-01

    Multivalued logical network consists of modules connected by multivalued signals. During synthesis each module is decomposed into smaller ones using the symbolic decomposition. Since the efficiency of the decomposition strongly depends on encoding of multivalued signals, the result of synthesis depends on the order, in which the consecutive modules are implemented. This paper presents the method of FPGA-oriented synthesis of multivalued logical networks. Experimental results showed that our approach significantly reduces the cost of implementation.

  15. Synthesis and Characterization of Hexagonal Boron Nitride (h- BN) Films

    DTIC Science & Technology

    2014-01-09

    Synthesis 1. Diborane- ammonia (B2H6-NH3- gases): Early results with these precursors were published in 2012. 5 Briefly, LPCVD growth of h-BN in a hot-wall...Approved for public release; distribution is unlimited. Synthesis and Characterization of Hexagonal Boron Nitride (h- BN) Films. The views, opinions and...1 ABSTRACT Number of Papers published in peer-reviewed journals: Synthesis and Characterization of Hexagonal Boron Nitride (h-BN) Films. Report Title

  16. Synthesis of Taylor and Bayliss patterns for linear antenna arrays

    NASA Astrophysics Data System (ADS)

    Shelton, J. P.

    1981-08-01

    The history of synthesis techniques for designing linear antenna arrays with low sidelobe patterns is reviewed briefly, and the limitations that are encountered with very low sidelobes and/or small arrays are pointed out. Taylor's continuous aperture synthesis procedure is outlined, and a technique for transforming it for application to a discrete array is described. Discrete-array design equation for Taylor and Bayliss synthesis procedures are given. A set of programs for use on a programmable calculator are presented.

  17. Direct electrical detection of DNA synthesis

    PubMed Central

    Pourmand, Nader; Karhanek, Miloslav; Persson, Henrik H. J.; Webb, Chris D.; Lee, Thomas H.; Zahradníková, Alexandra; Davis, Ronald W.

    2006-01-01

    Rapid, sequence-specific DNA detection is essential for applications in medical diagnostics and genetic screening. Electrical biosensors that use immobilized nucleic acids are especially promising in these applications because of their potential for miniaturization and automation. Current DNA detection methods based on sequencing by synthesis rely on optical readouts; however, a direct electrical detection method for this technique is not available. We report here an approach for direct electrical detection of enzymatically catalyzed DNA synthesis by induced surface charge perturbation. We discovered that incorporation of a complementary deoxynucleotide (dNTP) into a self-primed single-stranded DNA attached to the surface of a gold electrode evokes an electrode surface charge perturbation. This event can be detected as a transient current by a voltage-clamp amplifier. Based on current understanding of polarizable interfaces, we propose that the electrode detects proton removal from the 3′-hydroxyl group of the DNA molecule during phosphodiester bond formation. PMID:16614066

  18. Asymmetric synthesis using chiral-encoded metal

    PubMed Central

    Yutthalekha, Thittaya; Wattanakit, Chularat; Lapeyre, Veronique; Nokbin, Somkiat; Warakulwit, Chompunuch; Limtrakul, Jumras; Kuhn, Alexander

    2016-01-01

    The synthesis of chiral compounds is of crucial importance in many areas of society and science, including medicine, biology, chemistry, biotechnology and agriculture. Thus, there is a fundamental interest in developing new approaches for the selective production of enantiomers. Here we report the use of mesoporous metal structures with encoded geometric chiral information for inducing asymmetry in the electrochemical synthesis of mandelic acid as a model molecule. The chiral-encoded mesoporous metal, obtained by the electrochemical reduction of platinum salts in the presence of a liquid crystal phase and the chiral template molecule, perfectly retains the chiral information after removal of the template. Starting from a prochiral compound we demonstrate enantiomeric excess of the (R)-enantiomer when using (R)-imprinted electrodes and vice versa for the (S)-imprinted ones. Moreover, changing the amount of chiral cavities in the material allows tuning the enantioselectivity. PMID:27562028

  19. Total Synthesis and Study of Myrmicarin Alkaloids

    PubMed Central

    Ondrus, Alison E.

    2010-01-01

    The myrmicarins are a family of air and temperature sensitive alkaloids that possess unique structural features. Our concise enantioselective synthesis of the tricyclic myrmicarins enabled evaluation of a potentially biomimetic assembly of the complex members via direct dimerization of simpler structures. These studies revealed that myrmicarin 215B undergoes efficient and highly diastereoselective Brønsted acid-induced dimerization to generate a new heptacyclic structure, isomyrmicarin 430A. Mechanistic analysis demonstrated that heterodimerization between myrmicarin 215B and a conformationally restricted azafulvenium ion precursor afforded a functionalized isomyrmicarin 430A structure in a manner that was consistent with a highly efficient, non-concerted ionic process. Recent advancement in heterodimerization between tricyclic derivatives has enabled the preparation of strategically functionalized hexacyclic structures. The design and synthesis of structurally versatile dimeric compounds has greatly facilitated manipulation of these structures en route to more complex myrmicarin derivatives. PMID:19585010

  20. Asymmetric synthesis using chiral-encoded metal

    NASA Astrophysics Data System (ADS)

    Yutthalekha, Thittaya; Wattanakit, Chularat; Lapeyre, Veronique; Nokbin, Somkiat; Warakulwit, Chompunuch; Limtrakul, Jumras; Kuhn, Alexander

    2016-08-01

    The synthesis of chiral compounds is of crucial importance in many areas of society and science, including medicine, biology, chemistry, biotechnology and agriculture. Thus, there is a fundamental interest in developing new approaches for the selective production of enantiomers. Here we report the use of mesoporous metal structures with encoded geometric chiral information for inducing asymmetry in the electrochemical synthesis of mandelic acid as a model molecule. The chiral-encoded mesoporous metal, obtained by the electrochemical reduction of platinum salts in the presence of a liquid crystal phase and the chiral template molecule, perfectly retains the chiral information after removal of the template. Starting from a prochiral compound we demonstrate enantiomeric excess of the (R)-enantiomer when using (R)-imprinted electrodes and vice versa for the (S)-imprinted ones. Moreover, changing the amount of chiral cavities in the material allows tuning the enantioselectivity.

  1. Mechanism and regulation of eukaryotic protein synthesis.

    PubMed Central

    Merrick, W C

    1992-01-01

    This review presents a description of the numerous eukaryotic protein synthesis factors and their apparent sequential utilization in the processes of initiation, elongation, and termination. Additionally, the rare use of reinitiation and internal initiation is discussed, although little is known biochemically about these processes. Subsequently, control of translation is addressed in two different settings. The first is the global control of translation, which is effected by protein phosphorylation. The second is a series of specific mRNAs for which there is a direct and unique regulation of the synthesis of the gene product under study. Other examples of translational control are cited but not discussed, because the general mechanism for the regulation is unknown. Finally, as is often seen in an active area of investigation, there are several observations that cannot be readily accommodated by the general model presented in the first part of the review. Alternate explanations and various lines of experimentation are proposed to resolve these apparent contradictions. PMID:1620067

  2. Process for production desulfurized of synthesis gas

    DOEpatents

    Wolfenbarger, James K.; Najjar, Mitri S.

    1993-01-01

    A process for the partial oxidation of a sulfur- and silicate-containing carbonaceous fuel to produce a synthesis gas with reduced sulfur content which comprises partially oxidizing said fuel at a temperature in the range of 1900.degree.-2600.degree. F. in the presence of a temperature moderator, an oxygen-containing gas and a sulfur capture additive which comprises a calcium-containing compound portion, a sodium-containing compound portion, and a fluoride-containing compound portion to produce a synthesis gas comprising H.sub.2 and CO with a reduced sulfur content and a molten slag which comprises (1) a sulfur-containing sodium-calcium-fluoride silicate phase; and (2) a sodium-calcium sulfide phase.

  3. Polylactides-Methods of synthesis and characterization.

    PubMed

    Pretula, Julia; Slomkowski, Stanislaw; Penczek, Stanislaw

    2016-12-15

    Polylactides with various molar masses, microstructures and crystallinities are used as degradable and biocompatible polymers suitable for preparation of drug carriers and temporary medical implants. This paper presents state of current knowledge on synthesis of lactic acids, high purity lactide monomers and their polymerization. Syntheses of high molar mass polylactides by polycondensation of lactic acid and by ring-opening polymerization of lactides are described and their advantages and disadvantages are discussed. Mechanisms of lactide polymerization initiated by metal alkoxides are described. There are presented also results of more recent studies of polymerization initiated with the so-called "no metal" organocatalysts; both anionic and cationic. Presented are advantages and limitations of synthesis of PLA by all the major polymerization processes until now. Some properties of PLA and most important methods used for PLA characterization are also described.

  4. Magnetic control of the DNA synthesis

    NASA Astrophysics Data System (ADS)

    Buchachenko, Anatoly L.; Orlov, Alexei P.; Kuznetsov, Dmitry A.; Breslavskaya, Natalia N.

    2013-10-01

    By using polymerases β loaded with isotopic ions 24Mg2+, 25Mg2+ and 26Mg2+ magnetic isotope effect was detected: 25Mg2+ ions with magnetic nuclei 25Mg suppress enzymatic activity by 2-3 times with respect to that of polymerases β loaded by 24Mg2+ and 26Mg2+ ions. No difference in enzymatic activity of polymerases β with 24Mg2+ and 26Mg2+ ions exists. The rate of DNA synthesis strongly depends on the magnetic field. The polymerase chain reaction is also suppressed by 25Mg2+ ions with respect to the ions with nonmagnetic nuclei. Magnetic control of the DNA synthesis may be used for medical purposes.

  5. Nanocrystalline Zeolite Y: Synthesis and Characterization

    NASA Astrophysics Data System (ADS)

    Taufiqurrahmi, Niken; Rahman Mohamed, Abdul; Bhatia, Subhash

    2011-02-01

    Nanocrystalline zeolite has received significant attention in the catalysis community. Zeolites with a crystal size smaller than 100 nm are the potential replacement for existing zeolite catalysts due to its unique features with added advantages. Zeolite FAU type Y is one of the most studied framework of all zeolites, and has been used as catalysts for number of reactions in the refinery and petrochemical industry. The present paper covers the synthesis of nanocrystalline zeolite Y under hydrothermal conditions from clear synthesis mixtures. The crystal size of zeolite Y is influenced by temperature, aging time, alkalinity, and water content. The synthesized Y is characterized by X-ray diffraction (XRD), Fourier Transmission Infrared Sprectroscopy (FTIR), Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM) and Nitrogen Adsorption.

  6. Synthesis of silicon and germanium nanowires.

    SciTech Connect

    Clement, Teresa J.; Hsu, Julia W. P.

    2007-11-01

    The vapor-liquid-solid growth process for synthesis of group-IV semiconducting nanowires using silane, germane, disilane and digermane precursor gases has been investigated. The nanowire growth process combines in situ gold seed formation by vapor deposition on atomically clean silicon (111) surfaces, in situ growth from the gaseous precursor(s), and real-time monitoring of nanowire growth as a function of temperature and pressure by a novel optical reflectometry technique. A significant dependence on precursor pressure and growth temperature for the synthesis of silicon and germanium nanowires is observed, depending on the stability of the specific precursor used. Also, the presence of a nucleation time for the onset of nanowire growth has been found using our new in situ optical reflectometry technique.

  7. Total synthesis of palau'amine

    PubMed Central

    Namba, Kosuke; Takeuchi, Kohei; Kaihara, Yukari; Oda, Masataka; Nakayama, Akira; Nakayama, Atsushi; Yoshida, Masahiro; Tanino, Keiji

    2015-01-01

    Palau'amine has received a great deal of attention in the past two decades as an attractive synthetic target by virtue of its intriguing molecular architecture and significant immunosuppressive activity. Here we report the total synthesis of palau'amine characterized by the construction of an ABDE tetracyclic ring core including a trans-bicylo[3.3.0]octane skeleton at a middle stage of total synthesis. The ABDE tetracyclic ring core is constructed by a cascade reaction of a cleavage of the N–N bond, including simultaneous formation of imine, the addition of amide anion to the resulting imine (D-ring formation) and the condensation of pyrrole with methyl ester (B-ring formation) in a single step. The synthetic palau'amine is confirmed to exhibit excellent immunosuppressive activity. The present synthetic route has the potential to help elucidate a pharmacophore as well as the mechanistic details of immunosuppressive activity. PMID:26530707

  8. Green synthesis of silver nanoparticles using tannins

    NASA Astrophysics Data System (ADS)

    Raja, Pandian Bothi; Rahim, Afidah Abdul; Qureshi, Ahmad Kaleem; Awang, Khalijah

    2014-09-01

    Colloidal silver nanoparticles were prepared by rapid green synthesis using different tannin sources as reducing agent viz. chestnut (CN), mangrove (MG) and quebracho (QB). The aqueous silver ions when exposed to CN, MG and QB tannins were reduced which resulted in formation of silver nanoparticles. The resultant silver nanoparticles were characterized using UV-Visible, X-ray diffraction (XRD), scanning electron microscopy (SEM/EDX), and transmission electron microscopy (TEM) techniques. Furthermore, the possible mechanism of nanoparticles synthesis was also derived using FT-IR analysis. Spectroscopy analysis revealed that the synthesized nanoparticles were within 30 to 75 nm in size, while XRD results showed that nanoparticles formed were crystalline with face centered cubic geometry.

  9. Continuous synthesis of silicon carbide whiskers

    NASA Astrophysics Data System (ADS)

    Choi, Heon-Jin; Lee, June-Gunn

    1995-04-01

    Experimental synthesis of SiC whiskers coupled with thermodynamic calculations revealed the preferred reaction routes for the efficient synthesis of SiC whiskers. This formed the basis for the design of a continuous reactor, which consists of a boat-train loaded with silica-carbon mixture and iron-coated graphite substrate above it in an alumina-tube reactor. High-quality SiC whiskers have been grown with diameters of 1-3 micron. The yield was about 30% based on the silicon input as SiO2 and output as SiC whiskers. This demonstrates the feasibility of continuous SiC whiskers production without the additional processes of purification and classification.

  10. Optimal cooperative control synthesis of active displays

    NASA Technical Reports Server (NTRS)

    Garg, S.; Schmidt, D. K.

    1986-01-01

    The utility of augmenting displays to aid the human operator in controlling high order complex systems is well known. Analytical evaluation of various display designs for a simple k/s sup 2 plant in a compensatory tracking task using an optimal Control Model (OCM) of human behavior is carried out. This analysis reveals that significant improvement in performance should be obtained by skillful integration of key information into the display dynamics. The cooperative control synthesis technique previously developed to design pilot-optimal control augmentation is extended to incorporate the simultaneous design of performance enhancing augmented displays. The application of the cooperative control synthesis technique to the design of augmented displays is discussed for the simple k/s sup 2 plant. This technique is intended to provide a systematic approach to design optimally augmented displays tailored for specific tasks.

  11. Optimal cooperative control synthesis of active displays

    NASA Technical Reports Server (NTRS)

    Garg, S.; Schmidt, D. K.

    1985-01-01

    The utility of augmenting displays to aid the human operator in controlling high order complex systems is well known. Analytical evaluations of various display designs for a simple k/s-squared plant in a compensatory tracking task using an Optimal Control Model (OCM) of human behavior is carried out. This analysis reveals that significant improvement in performance should be obtained by skillful integration of key information into the display dynamics. The cooperative control synthesis technique previously developed to design pilot-optimal control augmentation is extended to incorporate the simultaneous design of performance enhancing augmented displays. The application of the cooperative control synthesis technique to the design of augmented displays is discussed for the simple k/s-squared plant. This technique is intended to provide a systematic approach to design optimally augmented displays tailored for specific tasks.

  12. Synthesis of peptide .alpha.-thioesters

    DOEpatents

    Camarero, Julio A.; Mitchell, Alexander R.; De Yoreo, James J.

    2008-08-19

    Disclosed herein is a new method for the solid phase peptide synthesis (SPPS) of C-terminal peptide .alpha. thioesters using Fmoc/t-Bu chemistry. This method is based on the use of an aryl hydrazine linker, which is totally stable to conditions required for Fmoc-SPPS. When the peptide synthesis has been completed, activation of the linker is achieved by mild oxidation. The oxidation step converts the acyl-hydrazine group into a highly reactive acyl-diazene intermediate which reacts with an .alpha.-amino acid alkylthioester (H-AA-SR) to yield the corresponding peptide .alpha.-thioester in good yield. A variety of peptide thioesters, cyclic peptides and a fully functional Src homology 3 (SH3) protein domain have been successfully prepared.

  13. A novel process for methanol synthesis

    SciTech Connect

    Tierney, J.W.; Wender, I.

    1993-02-12

    A bench-scale reactor is being used to conduct studies of the conversion of synthesis gas to methanol (MeOH) in the liquid phase by a novel process. In previous reports, we provided evidence for a two step reaction in series, the carbonylation reaction mainly takng place close and the hydrogenolysis reaction taking place on the surface of the copper chromate. The interaction between the two catalyst enhances the rate of MeOH formation. In the last quarter, we showed that under present operating conditions, the methyl formate (MeOH) concentration is not in equilibrium and hence both the carboxylation and the hydrogenolysis reactions influence the rate of MEOH formation. The activities of other alkali and alkaline earth compounds as catalysts, the effect of water and the controlling reaction in the concurrent synthesis is described in this report.

  14. Pyro-Synthesis of Functional Nanocrystals

    PubMed Central

    Gim, Jihyeon; Mathew, Vinod; Lim, Jinsub; Song, Jinju; Baek, Sora; Kang, Jungwon; Ahn, Docheon; Song, Sun-Ju; Yoon, Hyeonseok; Kim, Jaekook

    2012-01-01

    Despite nanomaterials with unique properties playing a vital role in scientific and technological advancements of various fields including chemical and electrochemical applications, the scope for exploration of nano-scale applications is still wide open. The intimate correlation between material properties and synthesis in combination with the urgency to enhance the empirical understanding of nanomaterials demand the evolution of new strategies to promising materials. Herein we introduce a rapid pyro-synthesis that produces highly crystalline functional nanomaterials under reaction times of a few seconds in open-air conditions. The versatile technique may facilitate the development of a variety of nanomaterials and, in particular, carbon-coated metal phosphates with appreciable physico-chemical properties benefiting energy storage applications. The present strategy may present opportunities to develop “design rules” not only to produce nanomaterials for various applications but also to realize cost-effective and simple nanomaterial production beyond lab-scale limitations. PMID:23230511

  15. Studies Toward the Total Synthesis of Eletefine

    NASA Astrophysics Data System (ADS)

    Rugg, Kyle William

    Eletefine is a natural product of the stephaoxocane family of alkaloids. It possesses an isoquinoline moiety functionalized with three methoxy groups forming an electron rich aromatic system. Eletefine also possesses a ten-membered ring with a novel bridged vinyl ether functionality, and a remote chiral alcohol, making it a conspicuous and desirable target for the synthetic organic chemist. The plant from which eletefine was first isolated (Cissampelos glaberrima ) has been used in traditional medicine for the relief of symptoms from urinary tract infections and asthma. The proposed synthesis of eletefine is a convergent route which features a Sonogashira coupling and a novel alkyne hydration. Herein, methods towards the synthesis of the model system des-hydroxyeletefine are described, in particular attempts towards formation of the AB ring system of des-hydroxyeletefine, as well as C8-C9 bond formation methodology via acylation and Sonogashira coupling.

  16. Approximation concepts for efficient structural synthesis

    NASA Technical Reports Server (NTRS)

    Schmit, L. A., Jr.; Miura, H.

    1976-01-01

    It is shown that efficient structural synthesis capabilities can be created by using approximation concepts to mesh finite element structural analysis methods with nonlinear mathematical programming techniques. The history of the application of mathematical programming techniques to structural design optimization problems is reviewed. Several rather general approximation concepts are described along with the technical foundations of the ACCESS 1 computer program, which implements several approximation concepts. A substantial collection of structural design problems involving truss and idealized wing structures is presented. It is concluded that since the basic ideas employed in creating the ACCESS 1 program are rather general, its successful development supports the contention that the introduction of approximation concepts will lead to the emergence of a new generation of practical and efficient, large scale, structural synthesis capabilities in which finite element analysis methods and mathematical programming algorithms will play a central role.

  17. Method and apparatus for producing synthesis gas

    DOEpatents

    Hemmings, John William; Bonnell, Leo; Robinson, Earl T.

    2010-03-03

    A method and apparatus for reacting a hydrocarbon containing feed stream by steam methane reforming reactions to form a synthesis gas. The hydrocarbon containing feed is reacted within a reactor having stages in which the final stage from which a synthesis gas is discharged incorporates expensive high temperature materials such as oxide dispersed strengthened metals while upstream stages operate at a lower temperature allowing the use of more conventional high temperature alloys. Each of the reactor stages incorporate reactor elements having one or more separation zones to separate oxygen from an oxygen containing feed to support combustion of a fuel within adjacent combustion zones, thereby to generate heat to support the endothermic steam methane reforming reactions.

  18. Thermodynamics of Strecker synthesis in hydrothermal systems

    NASA Technical Reports Server (NTRS)

    Schulte, Mitchell; Shock, Everett

    1995-01-01

    Submarine hydrothermal systems on the early Earth may have been the sites from which life emerged. The potential for Strecker synthesis to produce biomolecules (amino and hydroxy acids) from starting compounds (ketones, aldehydes, HCN and ammonia) in such environments is evaluated quantitatively using thermodynamic data and parameters for the revised Helgeson-Kirkham-Flowers (HKF) equation of state. Although there is an overwhelming thermodynamic drive to form biomolecules by the Strecker synthesis at hydrothermal conditions, the availability and concentration of starting compounds limit the efficiency and productivity of Strecker reactions. Mechanisms for concentrating reactant compounds could help overcome this problem, but other mechanisms for production of biomolecules may have been required to produce the required compounds on the early Earth. Geochemical constraints imposed by hydrothermal systems provide important clues for determining the potential of these and other systems as sites for the emergence of life.

  19. New generation of biocatalysts for organic synthesis.

    PubMed

    Nestl, Bettina M; Hammer, Stephan C; Nebel, Bernd A; Hauer, Bernhard

    2014-03-17

    The use of enzymes as catalysts for the preparation of novel compounds has received steadily increasing attention over the past few years. High demands are placed on the identification of new biocatalysts for organic synthesis. The catalysis of more ambitious reactions reflects the high expectations of this field of research. Enzymes play an increasingly important role as biocatalysts in the synthesis of key intermediates for the pharmaceutical and chemical industry, and new enzymatic technologies and processes have been established. Enzymes are an important part of the spectrum of catalysts available for synthetic chemistry. The advantages and applications of the most recent and attractive biocatalysts--reductases, transaminases, ammonia lyases, epoxide hydrolases, and dehalogenases--will be discussed herein and exemplified by the syntheses of interesting compounds.

  20. Large Area Synthesis of 2D Materials

    NASA Astrophysics Data System (ADS)

    Vogel, Eric

    Transition metal dichalcogenides (TMDs) have generated significant interest for numerous applications including sensors, flexible electronics, heterostructures and optoelectronics due to their interesting, thickness-dependent properties. Despite recent progress, the synthesis of high-quality and highly uniform TMDs on a large scale is still a challenge. In this talk, synthesis routes for WSe2 and MoS2 that achieve monolayer thickness uniformity across large area substrates with electrical properties equivalent to geological crystals will be described. Controlled doping of 2D semiconductors is also critically required. However, methods established for conventional semiconductors, such as ion implantation, are not easily applicable to 2D materials because of their atomically thin structure. Redox-active molecular dopants will be demonstrated which provide large changes in carrier density and workfunction through the choice of dopant, treatment time, and the solution concentration. Finally, several applications of these large-area, uniform 2D materials will be described including heterostructures, biosensors and strain sensors.