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Sample records for chemoenzymatically synthesized multimeric

  1. A chemo-enzymatic route to synthesize (S)-γ-valerolactone from levulinic acid.

    Science.gov (United States)

    Götz, Katharina; Liese, Andreas; Ansorge-Schumacher, Marion; Hilterhaus, Lutz

    2013-05-01

    Levulinic acid is a feasible platform chemical derived from acid-catalyzed hydrolysis of lignocellulose. The conversion of this substrate to (S)-γ-valerolactone ((S)-GVL) was investigated in a chemo-enzymatic reaction sequence that benefits from mild reaction conditions and excellent enantiomeric excess of the desired (S)-GVL. For that purpose, levulinic acid was chemically esterified over the ion exchange resin Amberlyst 15 to yield ethyl levulinate (LaOEt). The keto ester was successfully reduced by (S)-specific carbonyl reductase from Candida parapsilosis (CPCR2) in a substrate-coupled cofactor regeneration system utilizing isopropanol as cosubstrate. In classical batch experiments, a maximum conversion of 95 % was achieved using a 20-fold excess of isopropanol. Continuous reduction of LaOEt was carried out for 24 h, and a productivity of more than 5 mg (S)-ethyl-4-hydroxypentanoate (4HPOEt) per μg CPCR2 was achieved. Afterwards (S)-4HPOEt (>99%ee) was substituted to lipase-catalyzed lactonization using immobilized lipase B from Candida antarctica to yield (S)-GVL in 90 % overall yield and >99%ee. PMID:23296499

  2. In vitro growth of four individual human gut bacteria on oligosaccharides produced by chemoenzymatic synthesis

    DEFF Research Database (Denmark)

    Vigsnæs, Louise Kristine; Nakai, Hiroyuki; Hemmingsen, Lene;

    2013-01-01

    chemoenzymatic synthesis (i.e. reverse phosphorolysis or transglycosylation). Fourteen of the OS are not naturally occurring and five (β-d-glucosyl-fructose, β-d-glucosyl-xylitol, α-glucosyl-(1,4)-d-mannose, α-glucosyl-(1,4)-d-xylose; α-glucosyl-(1,4)-l-fucose) have recently been synthesized for the first time...

  3. Chemoenzymatic synthesis of spinosyn A.

    Science.gov (United States)

    Kim, Hak Joong; Choi, Sei-hyun; Jeon, Byung-sun; Kim, Namho; Pongdee, Rongson; Wu, Qingquan; Liu, Hung-wen

    2014-12-01

    Following the biosynthesis of polyketide backbones by polyketide synthases (PKSs), post-PKS modifications result in a significantly elevated level of structural complexity that renders the chemical synthesis of these natural products challenging. We report herein a total synthesis of the widely used polyketide insecticide spinosyn A by exploiting the prowess of both chemical and enzymatic methods. As more polyketide biosynthetic pathways are characterized, this chemoenzymatic approach is expected to become readily adaptable to streamlining the synthesis of other complex polyketides with more elaborate post-PKS modifications. PMID:25287333

  4. An Efficient Chemoenzymatic Process for Preparation of Ribavirin

    Directory of Open Access Journals (Sweden)

    Vladimir Sakharov

    2015-01-01

    Full Text Available Ribavirin is an important antiviral drug, which is used for treatment of many diseases. The pilot-scale chemoenzymatic process for synthesis of the active pharmaceutical ingredient Ribavirin was developed with 32% overall yield and more than 99.5% purity. The described method includes the chemical synthesis of 1,2,4-triazole-3-carboxamide, which is a key intermediate and enzyme-catalyzed transglycosylation reaction for preparation of the desired product. 1,2,4-Triazole-3-carboxamide was synthesized from 5-amino-1,2,4-triazole-3-carboxylic acid by classical Chipen-Grinshtein method. Isolated from E. сoli BL21(DE3/pERPUPHHO1 strain the purine nucleoside phosphorylase was used as a biocatalytical system. All steps of this process were optimized and scaled.

  5. Papain-Catalyzed Chemoenzymatic Synthesis of Telechelic Polypeptides Using Bis(Leucine Ethyl Ester) Initiator.

    Science.gov (United States)

    Tsuchiya, Kousuke; Numata, Keiji

    2016-07-01

    In order to construct unique polypeptide architectures, a novel telechelic-type initiator with two leucine ethyl ester units is designed for chemoenzymatic polymerization. Glycine or alanine ethyl ester is chemoenzymatically polymerized using papain in the presence of the initiator, and the propagation occurs at each leucine ethyl ester unit to produce the telechelic polypeptide. The formation of the telechelic polypeptides is confirmed by (1) H NMR and MALDI-TOF mass spectroscopies. It is revealed by AFM observation that long nanofibrils are formed from the telechelic polyalanine, whereas a conventional linear polyalanine with a similar degree of polymerization shows granule-like structures. The telechelic polyglycine and polyalanine show the crystalline structures of Polyglycine II and antiparallel β-sheet, respectively. It is demonstrated that this method to synthesize telechelic-type polypeptides potentially opens up a pathway to construct novel hierarchical structures by self-assembly. PMID:26947148

  6. Chemo-enzymatic synthesis of vinyl and l-ascorbyl phenolates and their inhibitory effects on advanced glycation end products.

    Science.gov (United States)

    Hwang, Seung Hwan; Wang, Zhiqiang; Lim, Soon Sung

    2017-01-01

    This study successfully established the feasibility of a two-step chemo-enzymatic synthesis of l-ascorbyl phenolates. Intermediate vinyl phenolates were first chemically produced and then underwent trans-esterification with l-ascorbic acid in the presence of Novozyme 435® (Candida Antarctica lipase B) as a catalyst. Twenty vinyl phenolates and 11 ascorbyl phenolates were subjected to in vitro bioassays to investigate their inhibitory activity against advanced glycation end products (AGEs). Among them, vinyl 4-hydroxycinnamate (17VP), vinyl 4-hydroxy-3-methoxycinnamate (18VP), vinyl 4-hydroxy-3,5-dimethoxycinnamate (20VP), ascorbyl 4-hydroxy-3-methoxycinnamate (18AP) and ascorbyl 3,4-dimethoxycinnamate (19AP) showed 2-10 times stronger inhibitory activities than positive control (aminoguanidine and its precursors). These results indicated that chemo-enzymatically synthesized compounds have AGE inhibitory effect and thus are effective in either preventing or retarding glycation protein formation. PMID:27507531

  7. Regulation of Adiponectin Multimerization, Signaling and Function

    OpenAIRE

    Liu, Meilian; Liu, Feng

    2013-01-01

    Adiponectin, which exists in serum in three major complexes including trimer, hexamer, and the high molecular weight (HMW) form, has strong insulin sensitizing, antiinflammatory and anti-diabetic functions. Different adiponectin complexes exert tissue-specific biological functions and activate distinct signaling pathways. In this review, we summarize our current understanding on the mechanisms regulating adiponectin multimerization. We also describe the major target tissues in which distinct ...

  8. Chemoenzymatic Synthesis of Oligo(L-cysteine) for Use as a Thermostable Bio-Based Material.

    Science.gov (United States)

    Ma, Yinan; Sato, Ryota; Li, Zhibo; Numata, Keiji

    2016-01-01

    Oligomerization of thiol-unprotected L-cysteine ethyl ester (Cys-OEt) catalyzed by proteinase K in aqueous solution has been used to synthesize oligo(L-cysteine) (OligoCys) with a well-defined chemical structure and relatively large degree of polymerization (DP) up to 16-17 (average 8.8). By using a high concentration of Cys-OEt, 78.0% free thiol content was achieved. The thermal properties of OligoCys are stable, with no glass transition until 200 °C, and the decomposition temperature could be increased by oxidation. Chemoenzymatically synthesized OligoCys has great potential for use as a thermostable bio-based material with resistance to oxidation. PMID:26388290

  9. SC-CO2 as green solvent for chemoenzymatic reaction

    Czech Academy of Sciences Publication Activity Database

    Zarevúcka, Marie; Sovová, Helena; Wimmer, Zdeněk

    Bari : ACE, 2004. s. -. [European Meeting on Environmental Chemistry /5./. 15.12.2004-18.12.2004, Bari] R&D Projects: GA ČR GA203/04/0120 Keywords : chemoenzymatic reaction * SC-CO2 Subject RIV: CC - Organic Chemistry

  10. Chemoenzymatic synthesis of enantiomerically enriched alpha-hydroxyamides

    NARCIS (Netherlands)

    Szymanski, Wiktor; Ostaszewski, Ryszard

    2007-01-01

    A study on a chemoenzymatic synthesis of model alpha-hydroxyamide was performed. Special attention was paid to the optimization of the enzymatic process, both on the selection of enzyme and cosolvent. An intriguing influence of cosolvent on the enantioselectivity of Wheat Germ Lipase and Amano PS Li

  11. Chemoenzymatic synthesis of organoselenium(IV) compounds and their evaluation as cysteine protease inhibitors

    International Nuclear Information System (INIS)

    A series of organoselenium dihalides (organoselenanes) was synthesized from organoselenides using a chemoenzymatic approach. The organoselenanes have variations in their stereochemistry and in the halogen atom bonded to the selenium atom. Because of the unique selenium-thiol chemistry displayed by several organoselenium compounds, the organoselenanes were evaluated as new potential inhibitors of cysteine proteases (cathepsins S and V). By the analysis of the second-order rate constants of the inhibition of cathepsin S and V, it was possible to conclude that organoselenanes inhibited the cathepsin S faster than cathepsin V. It was observed higher inhibitory potencies for the dibromo organoselenanes derivatives than the dichloro analogues. In addition, the present data suggest the use of hypervalent selenium compounds as novel motifs for cysteine proteases inhibitors. (author)

  12. Chemoenzymatic synthesis of organoselenium(IV) compounds and their evaluation as cysteine protease inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Piovan, Leandro; Andrade, Leandro H., E-mail: leandroh@iq.usp.b [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Quimica; Alves, Marcio F.M.; Juliano, Luiz; Cunha, Rodrigo L.O.R, E-mail: rodrigo.cunha@ufabc.edu.b [Universidade Federal de Sao Paulo (Unifesp/EPM), Sao Paulo, SP (Brazil). Dept. de Biofisica; Broemme, Dieter [University of British Columbia, Vancouver (Canada). Dept. of Dentistry

    2010-07-01

    A series of organoselenium dihalides (organoselenanes) was synthesized from organoselenides using a chemoenzymatic approach. The organoselenanes have variations in their stereochemistry and in the halogen atom bonded to the selenium atom. Because of the unique selenium-thiol chemistry displayed by several organoselenium compounds, the organoselenanes were evaluated as new potential inhibitors of cysteine proteases (cathepsins S and V). By the analysis of the second-order rate constants of the inhibition of cathepsin S and V, it was possible to conclude that organoselenanes inhibited the cathepsin S faster than cathepsin V. It was observed higher inhibitory potencies for the dibromo organoselenanes derivatives than the dichloro analogues. In addition, the present data suggest the use of hypervalent selenium compounds as novel motifs for cysteine proteases inhibitors. (author)

  13. Chemoenzymatic combination of glucose oxidase with titanium silicalite -1

    DEFF Research Database (Denmark)

    Vennestrøm, Peter Nicolai Ravnborg; Taarning, Esben; Christensen, Claus H.;

    2010-01-01

    Zeozymes: A proof-of-concept is presented for the chemoenzymatic combination of titanium silicalite-1 zeolite with glucose oxidase. In this combination, glucose is oxidized to gluconic acid and the H2O2 byproduct formed in situ is used for the simultaneous oxidation of chemical substrates. Both a...... soluble glucose oxidase and a truly integrated heterogeneous combination whereby the oxidase enzyme is anchored onto the zeolite surface are reported....

  14. Chemoenzymatic synthesis of 5-thio-D-xylopyranose.

    OpenAIRE

    Charmantray, Franck; Dellis, Philippe; Hélaine, Virgil; Samreth, Soth; Hecquet, Laurence

    2006-01-01

    5-thio-D-xylopyranose, a synthon used for the preparation of drugs with antithrombotic activity, was synthesised by an enzymatic isomerisation from the corresponding ketose, 5-thio-D-xylulofuranose, with glucose isomerase. This compound was obtained by two different chemoenzymatic routes, the key step being the stereospecific formation of a C-C bond, catalysed by transketolase or fructose-1,6-bisphosphate aldolase

  15. Chemo-enzymatic peptide synthesis : bioprocess engineering aspects

    OpenAIRE

    Vossenberg, P.

    2012-01-01

      Peptides, in particular oligopeptides, play an important role in the fields of health care, nutrition and cosmetics. Chemical synthesis is currently the most mature technique for the synthesis of peptides that range in length from 5 to 80 amino acids. Chemical synthesis is, however, expected to be more and more combined with enzyme-catalyzed synthesis, resulting in chemo-enzymatic approaches towards peptide synthesis. The racemization that hampers chemical synthesis can be prevented by...

  16. Ligand recognition by E- and P-selectin : chemoenzymatic synthesis and inhibitory activity of bivalent sialyl Lewis x derivatives and sialyl Lewis x carboxylic acids

    OpenAIRE

    Wittmann, Valentin; Takayama, Shuichi; Gong, Ke Wei; Weitz-Schmidt, Gabriele; Wong, Chi-Huey

    1998-01-01

    Described is the preparation of five sLex dimers and five sLex carboxylic acids by coupling chemoenzymatically synthesized amino-substituted sialyl Lewis x (sLex) derivative 4 to homobifunctional cross-linkers 20-24 of varying chain length. 20-24 were obtained by alkylating low-molecular-weight oligoethylene glycols with tert-butyl bromoacetate and subsequent transformation of the di-tert-butyl esters into disuccinimide esters. The products were assayed for inhibition against binding of a sLe...

  17. Casuarine stereoisomers from achiral substrates: chemoenzymatic synthesis and inhibitory properties.

    Science.gov (United States)

    Concia, Alda Lisa; Gómez, Livia; Parella, Teodor; Joglar, Jesús; Clapés, Pere

    2014-06-01

    A straightforward chemoenzymatic synthesis of four uncovered casuarine stereoisomers is described. The strategy consists of L-fuculose-1-phosphate aldolase F131A-variant-catalyzed aldol addition of dihydroxyacetone phosphate to aldehyde derivatives of 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) and its enantiomer (LAB) and subsequent one-pot catalytic deprotection-reductive amination. DAB and LAB were obtained from dihydroxyacetone and aminoethanol using D-fructose-6-phosphate aldolase and L-rhamnulose-1-phosphate aldolase catalysts, respectively. The new ent-3-epi-casuarine is a strong inhibitor of α-d-glucosidase from rice and of rat intestinal sucrase. PMID:24810734

  18. Structural Characterisation by ESI-MS of Feruloylated Arabino-oligosaccharides Synthesised by Chemoenzymatic Esterification

    Directory of Open Access Journals (Sweden)

    Paul Christakopoulos

    2007-07-01

    Full Text Available The chemoenzymatic synthesis of feruloylated arabino-oligosaccharides has been achieved, using a feruloyl esterase type C from Sporotrichum thermophile (StFaeC.The structure of the feruloylated products was confirmed by ESI-MSn.

  19. Multimeric, Multifunctional Derivatives of Poly(ethylene glycol

    Directory of Open Access Journals (Sweden)

    Gian Maria Bonora

    2011-07-01

    Full Text Available This article reviews the use of multifunctional polymers founded on high-molecular weight poly(ethylene glycol (PEG. The design of new PEG derivatives assembled in a dendrimer-like multimeric fashion or bearing different functionalities on the same molecule is described. Their use as new drug delivery systems based on the conjugation of multiple copies or diversely active drugs on the same biocompatible support is illustrated.

  20. Multimeric, Multifunctional Derivatives of Poly(ethylene glycol)

    OpenAIRE

    Gian Maria Bonora; Francesca Cateni; Marina Zacchigna; Sara Drioli

    2011-01-01

    This article reviews the use of multifunctional polymers founded on high-molecular weight poly(ethylene glycol) (PEG). The design of new PEG derivatives assembled in a dendrimer-like multimeric fashion or bearing different functionalities on the same molecule is described. Their use as new drug delivery systems based on the conjugation of multiple copies or diversely active drugs on the same biocompatible support is illustrated.

  1. In vitro growth of four individual human gut bacteria on oligosaccharides produced by chemoenzymatic synthesis.

    Science.gov (United States)

    Vigsnaes, Louise K; Nakai, Hiroyuki; Hemmingsen, Lene; Andersen, Joakim M; Lahtinen, Sampo J; Rasmussen, Louise E; Hachem, Maher Abou; Petersen, Bent O; Duus, Jens Ø; Meyer, Anne S; Licht, Tine R; Svensson, Birte

    2013-04-30

    The present study aimed at examining oligosaccharides (OS) for potential stimulation of probiotic bacteria. Nineteen structurally well-defined candidate OS covering groups of β-glucosides, α-glucosides and α-galactosides with degree of polymerization 2-4 were prepared in >100 mg amounts by chemoenzymatic synthesis (i.e. reverse phosphorolysis or transglycosylation). Fourteen of the OS are not naturally occurring and five (β-D-glucosyl-fructose, β-D-glucosyl-xylitol, α-glucosyl-(1,4)-D-mannose, α-glucosyl-(1,4)-D-xylose; α-glucosyl-(1,4)-L-fucose) have recently been synthesized for the first time. These OS have not been previously tested for effects of bacterial growth and here the ability of all 19 OS to support growth of four gastrointestinal bacteria: three probiotic bacteria Bifidobacterium lactis, Bifidobacterium longum, and Lactobacillus acidophilus, and one commensal bacterium, Bacteroides vulgatus has been evaluated in monocultures. The disaccharides β-D-glucosyl-xylitol and β-D-glucosyl-(1,4)-xylose noticeably stimulated growth yields of L. acidophilus NCFM, and additionally, β-D-glucosyl-(1,4)-xylose stimulated B. longum Bl-05. α-Glucosyl-(1,4)-glucosamine and α-glucosyl-(1,4)-N-acetyl-glucosamine enhanced the growth rate of B. animalis subsp. lactis and B. longum Bl-05, whereas L. acidophilus NCFM and Bac. vulgatus did not grow on these OS. α-Galactosyl-(1,6)-α-galactosyl-(1,6)-glucose advanced the growth rate of B. animalis subsp. lactis and L. acidophilus NCFM. Thus several of the structurally well-defined OS supported growth of beneficial gut bacteria. This reflects a broad specificity of their sugar transporters for OS, including specificity for non-naturally occurring OS, hence showing promise for design of novel prebiotics. PMID:23580006

  2. A Chemo-Enzymatic Road Map to the Synthesis of CoA Esters.

    Science.gov (United States)

    Peter, Dominik M; Vögeli, Bastian; Cortina, Niña Socorro; Erb, Tobias J

    2016-01-01

    Coenzyme A (CoA) is a ubiquitous cofactor present in every known organism. The thioesters of CoA are core intermediates in many metabolic processes, such as the citric acid cycle, fatty acid biosynthesis and secondary metabolism, including polyketide biosynthesis. Synthesis of CoA-thioesters is vital for the study of CoA-dependent enzymes and pathways, but also as standards for metabolomics studies. In this work we systematically tested five chemo-enzymatic methods for the synthesis of the three most abundant acyl-CoA thioester classes in biology; saturated acyl-CoAs, α,β-unsaturated acyl-CoAs (i.e., enoyl-CoA derivatives), and α-carboxylated acyl-CoAs (i.e., malonyl-CoA derivatives). Additionally we report on the substrate promiscuity of three newly described acyl-CoA dehydrogenases that allow the simple conversion of acyl-CoAs into enoyl-CoAs. With these five methods, we synthesized 26 different CoA-thioesters with a yield of 40% or higher. The CoA esters produced range from short- to long-chain, include branched and α,β-unsaturated representatives as well as other functional groups. Based on our results we provide a general guideline to the optimal synthesis method of a given CoA-thioester in respect to its functional group(s) and the commercial availability of the precursor molecule. The proposed synthetic routes can be performed in small scale and do not require special chemical equipment, making them convenient also for biological laboratories. PMID:27104508

  3. A Chemo-Enzymatic Road Map to the Synthesis of CoA Esters

    Directory of Open Access Journals (Sweden)

    Dominik M. Peter

    2016-04-01

    Full Text Available Coenzyme A (CoA is a ubiquitous cofactor present in every known organism. The thioesters of CoA are core intermediates in many metabolic processes, such as the citric acid cycle, fatty acid biosynthesis and secondary metabolism, including polyketide biosynthesis. Synthesis of CoA-thioesters is vital for the study of CoA-dependent enzymes and pathways, but also as standards for metabolomics studies. In this work we systematically tested five chemo-enzymatic methods for the synthesis of the three most abundant acyl-CoA thioester classes in biology; saturated acyl-CoAs, α,β-unsaturated acyl-CoAs (i.e., enoyl-CoA derivatives, and α-carboxylated acyl-CoAs (i.e., malonyl-CoA derivatives. Additionally we report on the substrate promiscuity of three newly described acyl-CoA dehydrogenases that allow the simple conversion of acyl-CoAs into enoyl-CoAs. With these five methods, we synthesized 26 different CoA-thioesters with a yield of 40% or higher. The CoA esters produced range from short- to long-chain, include branched and α,β-unsaturated representatives as well as other functional groups. Based on our results we provide a general guideline to the optimal synthesis method of a given CoA-thioester in respect to its functional group(s and the commercial availability of the precursor molecule. The proposed synthetic routes can be performed in small scale and do not require special chemical equipment, making them convenient also for biological laboratories.

  4. Functional Multimerization of the Human Telomerase Reverse Transcriptase

    OpenAIRE

    Beattie, Tara L.; Zhou, Wen; Robinson, Murray O.; Harrington, Lea

    2001-01-01

    The telomerase enzyme exists as a large complex (∼1,000 kDa) in mammals and at minimum is composed of the telomerase RNA and the catalytic subunit telomerase reverse transcriptase (TERT). In Saccharomyces cerevisiae, telomerase appears to function as an interdependent dimer or multimer in vivo (J. Prescott and E. H. Blackburn, Genes Dev. 11:2790–2800, 1997). However, the requirements for multimerization are not known, and it remained unclear whether telomerase exists as a multimer in other or...

  5. Chemoenzymatic synthesis of 1-deaza-pyridoxal 5’-phosphate

    OpenAIRE

    Griswold, Wait R.; Toney, Michael D.

    2010-01-01

    The first synthesis of 1-deaza-pyridoxal 5’-phosphate (2-formyl-3-hydroxy-4-methylbenzyl phosphate) is described. The chemoenzymatic approach described here is a reliable route to this important isosteric pyridoxal phosphate analogue. This work enables elucidation of the role of the pyridine nitrogen in pyridoxal 5’-phosphate dependent enzymes.

  6. Reversible derivatization to enhance enzymatic synthesis: Chemoenzymatic synthesis of Doxorubicin-14-O-Esters

    Science.gov (United States)

    An efficient three-step, chemoenzymatic synthesis of unprotected doxorubicin-14-O-esters from doxorubicin hydrochloride salt is described. The key step is a lipase-catalyzed regioselective transesterification/esterification using commercially-available acyl donors and doxorubicin reversibly derivat...

  7. The ability of multimerized cyclophilin A to restrict retrovirus infection.

    Science.gov (United States)

    Javanbakht, Hassan; Diaz-Griffero, Felipe; Yuan, Wen; Yeung, Darwin F; Li, Xing; Song, Byeongwoon; Sodroski, Joseph

    2007-10-10

    In owl monkeys, the typical retroviral restriction factor of primates, TRIM5alpha, is replaced by TRIMCyp. TRIMCyp consists of the TRIM5 RING, B-box 2 and coiled-coil domains, as well as the intervening linker regions, fused with cyclophilin A. TRIMCyp restricts infection of retroviruses, such as human immunodeficiency virus (HIV-1) and feline immunodeficiency virus (FIV), with capsids that can bind cyclophilin A. The TRIM5 coiled coil promotes the trimerization of TRIMCyp. Here we show that cyclophilin A that is oligomeric as a result of fusion with a heterologous multimer exhibits substantial antiretroviral activity. The addition of the TRIM5 RING, B-box 2 and Linker 2 to oligomeric cyclophilin A generated a protein with antiretroviral activity approaching that of wild-type TRIMCyp. Multimerization increased the binding of cyclophilin A to the HIV-1 capsid, promoting accelerated uncoating of the capsid and restriction of infection. PMID:17574642

  8. The ability of multimerized cyclophilin A to restrict retrovirus infection

    International Nuclear Information System (INIS)

    In owl monkeys, the typical retroviral restriction factor of primates, TRIM5α, is replaced by TRIMCyp. TRIMCyp consists of the TRIM5 RING, B-box 2 and coiled-coil domains, as well as the intervening linker regions, fused with cyclophilin A. TRIMCyp restricts infection of retroviruses, such as human immunodeficiency virus (HIV-1) and feline immunodeficiency virus (FIV), with capsids that can bind cyclophilin A. The TRIM5 coiled coil promotes the trimerization of TRIMCyp. Here we show that cyclophilin A that is oligomeric as a result of fusion with a heterologous multimer exhibits substantial antiretroviral activity. The addition of the TRIM5 RING, B-box 2 and Linker 2 to oligomeric cyclophilin A generated a protein with antiretroviral activity approaching that of wild-type TRIMCyp. Multimerization increased the binding of cyclophilin A to the HIV-1 capsid, promoting accelerated uncoating of the capsid and restriction of infection

  9. Chemoenzymatic synthesis, characterization, and application of glycopolymers carrying lactosamine repeats as entry inhibitors against influenza virus infection.

    Science.gov (United States)

    Hidari, Kazuya I P J; Murata, Takeomi; Yoshida, Kazuhiro; Takahashi, Yoshiharu; Minamijima, Yo-hei; Miwa, Yoshinobu; Adachi, Satoshi; Ogata, Makoto; Usui, Taiichi; Suzuki, Yasuo; Suzuki, Takashi

    2008-10-01

    To control interspecies transmission of influenza viruses, it is essential to elucidate the molecular mechanisms of the interaction of influenza viruses with sialo-glycoconjugate receptors expressed on different host cells. Competitive inhibitors containing mimetic receptor carbohydrates that prevent virus entry may be useful tools to address such issues. We chemoenzymatically synthesized and characterized the glycopolymers that were carrying terminal 2,6-sialic acid on lactosamine repeats as influenza virus inhibitors. In vitro and in vivo infection experiments using these glycopolymers demonstrated marked differences in inhibitory activity against different species of viruses. Human viruses, including clinically isolated strains, were consistently inhibited by glycopolymers carrying lactosamine repeats with higher activity than those containing a single lactosamine. A swine virus also showed the same recognition properties as those from human hosts. In contrast, avian and equine viruses were not inhibited by any of the glycopolymers examined carrying single, tandem, or triplet lactosamine repeats. Hemagglutination inhibition and solid-phase binding analyses indicated that binding affinity of glycopolymers with influenza viruses contributes dominantly to the inhibitory activity against viral infection. Sequence analysis and molecular modeling of human viruses indicated that specific amino acid substitutions on hemagglutinin may affect binding affinity of glycopolymers carrying lactosamine repeats with viruses. In conclusion, glycopolymers carrying lactosamine repeats of different lengths are useful to define molecular mechanisms of virus recognition. The core carbohydrate portion as well as sialyl linkages on the receptor glycoconjugate may affect host cell recognition of human and swine viruses. PMID:18621993

  10. An investigation of nitrile transforming enzymes in the chemo-enzymatic synthesis of the taxol sidechain

    OpenAIRE

    Wilding, Birgit; Veselá, Alicja; Perry, Justin; Black, Gary; ZHANG Meng; Martínková, Ludmila; Klempier, Norbert

    2015-01-01

    Paclitaxel (taxol) is an antimicrotubule agent widely used in the treatment of cancer. Taxol is prepared in a semisynthetic route by coupling the N-benzoyl-(2R,3S)-3-phenylisoserine sidechain to the baccatin III core structure. Precursors of the taxol sidechain have previously been prepared in chemoenzymatic approaches using acylases, lipases, and reductases, mostly featuring the enantioselective, enzymatic step early in the reaction pathway. Here, nitrile hydrolysing enzymes, namely nitrile ...

  11. Synthese, Charakterisierung und Evaluierung von Antikörperkonjugaten mit Dendrimer-basierten Chelator- und Fluoreszenzfarbstoffmultimeren für die Krebsdiagnostik und Therapie

    OpenAIRE

    Wängler, Carmen

    2007-01-01

    Für eine Verbesserung der radiometallbasierten Diagnostik und Therapie sowie der Diagnostik mittels Fluoreszenzfarbstoffen wurden Chelatbildner- und Fluoreszenz-farbstoff-Multimere auf der Basis von PAMAM-Dendrimeren hergestellt. Diese wurden in den EGF-Rezeptor bindenden Antikörper Matuzumab eingeführt und die synthetisierten Antikörper-Multimer-Konjugate hinsichtlich ihrer Immunreaktivität untersucht. Für die Herstellung der Multimere musste zunächst die Synthese der PAMAM-Dendrimere optimi...

  12. The role of lysine 186 in HIV-1 integrase multimerization

    International Nuclear Information System (INIS)

    HIV-1 integrase (IN) catalyzes biochemical reactions required for viral cDNA insertion into host cell chromosomal DNA, an essential step in the HIV-1 replication cycle. In one of these reactions, the two ends of the linear viral cDNA are believed to be simultaneously ligated to chromosomal DNA by a tetrameric form of IN. The structure of the full-length IN tetramer is not known but a model consisting of the N-terminal domain and the catalytic core revealed basic residues 186 to 188 at the interface between the two IN dimers. We found that alteration of these residues, in particular changing IN lysine residue 186 to glutamate (K186Q), impairs IN oligomerization in the yeast two-hybrid system and decreases oligomeric forms of IN within virions. When expressed independently of other viral proteins in human cells, IN-K186Q did not concentrate in the nucleus as did wild-type IN. Co-expression of wild-type IN restored the multimerization defects of IN-K186Q, in both the two-hybrid system and in virions, and also rescued the nuclear targeting defects. Virions bearing IN-K186Q were not infectious in a single cycle of replication but when mixed virions containing two different IN mutants were produced, IN-K186Q was capable of complementing the catalytically inactive mutant IN-D116A. Our biochemical and functional data support the crystallographic model in which IN residue K186 lies at the interface between IN dimers and suggest that tetramerization is important, not only for concerted integration, but also for IN nuclear targeting

  13. Facile and high-efficient immobilization of histidine-tagged multimeric protein G on magnetic nanoparticles

    Science.gov (United States)

    Lee, Jiho; Chang, Jeong Ho

    2014-12-01

    This work reports the high-efficient and one-step immobilization of multimeric protein G on magnetic nanoparticles. The histidine-tagged (His-tag) recombinant multimeric protein G was overexpressed in Escherichia coli BL21 by the repeated linking of protein G monomers with a flexible linker. High-efficient immobilization on magnetic nanoparticles was demonstrated by two different preparation methods through the amino-silane and chloro-silane functionalization on silica-coated magnetic nanoparticles. Three kinds of multimeric protein G such as His-tag monomer, dimer, and trimer were tested for immobilization efficiency. For these tests, bicinchoninic acid (BCA) assay was employed to determine the amount of immobilized His-tag multimeric protein G. The result showed that the immobilization efficiency of the His-tag multimeric protein G of the monomer, dimer, and trimer was increased with the use of chloro-silane-functionalized magnetic nanoparticles in the range of 98% to 99%, rather than the use of amino-silane-functionalized magnetic nanoparticles in the range of 55% to 77%, respectively.

  14. Chemoenzymatic synthesis of L-tyrosine derivative for a transketolase assay

    OpenAIRE

    Charmantray, Franck; Hélaine, Virgil; Lasikova, Angelika; Legeret, Bertrand; Hecquet, Laurence

    2008-01-01

    We have prepared an l-tyrosine derivative bearing a d-threo ketose moiety by a convenient chemoenzymatic route. This compound is of potential interest for developing stereospecific assays for enzymes catalyzing C–C bond cleavage such as transketolase. We showed in vitro by analytical studies (LC/MS and 31P NMR) that this compound can release l-tyrosine in the presence of wild type TK extract and bovine serum albumin. This assay is the first step towards a mutant TK selection test that could b...

  15. Chemo-enzymatic synthesis of the carbohydrate antigen N-glycolylneuraminic acid from glucose

    OpenAIRE

    Pearce, Oliver M. T.; Varki, Ajit

    2010-01-01

    N-Glycolylneuraminic acid (Neu5Gc) is a non-human sialic acid, which may play a significant role in human pathologies, such as cancer, and vascular disease. Further studies into the role of Neu5Gc in human disease is hindered by limited sources of this carbohydrate. Using a chemoenzymatic approach, Neu5Gc was accessed in 6 steps from glucose. The synthesis allows access to gram scale quantities quickly and economically, and produces Neu5Gc in superior quality to commercial sources. Finally, w...

  16. Multimeric small interfering ribonucleic acid for highly efficient sequence-specific gene silencing

    Science.gov (United States)

    Mok, Hyejung; Lee, Soo Hyeon; Park, Ji Won; Park, Tae Gwan

    2010-03-01

    Small interfering RNA (siRNA) with 19-21 base pairs has been recently recognized as a new therapeutic agent for effectively silencing a specific gene on a post-transcription level. For siRNA therapeutics, safe and efficient delivery issues are significant hurdles to clinical applications. Here we present a new class of biologically active siRNA structure based on chemically self-crosslinked and multimerized siRNA through cleavable disulphide linkages. The multimerized siRNA can produce more stable and compact polyelectrolyte complexes with less cytotoxic cationic carriers than naked siRNA because of substantially increased charge densities and the presence of flexible chemical linkers in the backbone. The cleavable and multimerized siRNA shows greatly enhanced gene-silencing efficiencies in vitro and in vivo through a target-messenger-RNA-specific RNA interference processing without significantly eliciting immune induction. This study demonstrates that the multimerized siRNA structure complexed with selected cationic condensing agents can serve as potential gene-silencing therapeutics for treating various diseases.

  17. Highly efficient antibody immobilization with multimeric protein Gs coupled magnetic silica nanoparticles

    Science.gov (United States)

    Lee, J. H.; Choi, H. K.; Chang, J. H.

    2011-10-01

    This work reports the immobilization of monomeric, dimeric and trimer protein Gs onto silica magnetic nanoparticles for self-oriented antibody immobilization. To achieve this, we initially prepared the silica-coated magnetic nanoparticle having about 170 nm diameters. The surface of the silica coated magnetic nanoparticles was modified with 3- aminopropyl-trimethoxysilane (APTMS) to chemically link to multimeric protein Gs. The conjugation of amino groups on the SiO2-MNPs to cysteine tagged in multimeric protein Gs was performed using a sulfo-SMCC coupling procedure. The binding efficiencies of monomer, dimer and trimer were 77 %, 67 % and 55 % respectively. However, the efficiencies of antibody immobilization were 70 %, 83 % and 95 % for monomeric, dimeric and trimeric protein G, respectively. To prove the enhancement of accessibility by using multimeric protein G, FITC labeled goat-anti-mouse IgG was treated to mouse IgG immobilized magnetic silica nanoparticles through multimeric protein G. FITC labeled goat anti-mouse IgGs were more easily bound to mouse IgG immobilized by trimeric protein G than others. Finally protein G bound silica magnetic nanoparticles were utilized to develop highly sensitive immunoassay to detect hepatitis B antigen.

  18. Chemoenzymatic dynamic kinetic resolution of primary amines using a recyclable palladium nanoparticle catalyst together with lipases.

    Science.gov (United States)

    Gustafson, Karl P J; Lihammar, Richard; Verho, Oscar; Engström, Karin; Bäckvall, Jan-E

    2014-05-01

    A catalyst consisting of palladium nanoparticles supported on amino-functionalized siliceous mesocellular foam (Pd-AmP-MCF) was used in chemoenzymatic dynamic kinetic resolution (DKR) to convert primary amines to amides in high yields and excellent ee's. The efficiency of the nanocatalyst at temperatures below 70 °C enables reaction conditions that are more suitable for enzymes. In the present study, this is exemplified by subjecting 1-phenylethylamine (1a) and analogous benzylic amines to DKR reactions using two commercially available lipases, Novozyme-435 (Candida antartica Lipase B) and Amano Lipase PS-C1 (lipase from Burkholderia cepacia) as biocatalysts. The latter enzyme has not previously been used in the DKR of amines because of its low stability at temperatures over 60 °C. The viability of the heterogeneous Pd-AmP-MCF was further demonstrated in a recycling study, which shows that the catalyst can be reused up to five times. PMID:24724828

  19. Maternal and Cord Blood Adiponectin Multimeric Forms in Gestational Diabetes Mellitus

    OpenAIRE

    Ballesteros, Mónica; Simón, Inmaculada; Vendrell, Joan; Ceperuelo-Mallafré, Victoria; Miralles, Ramon M.; Albaiges, Gerard; Tinahones, Francisco; Megia, Ana

    2011-01-01

    OBJECTIVE To analyze the relationship between maternal adiponectin (mAdiponectin) and cord blood adiponectin (cbAdiponectin) multimeric forms (high molecular weight [HMW], medium molecular weight [MMW], and low molecular weight [LMW]) in a cohort of gestational diabetes mellitus (GDM) and normal glucose–tolerant (NGT) pregnant women. RESEARCH DESIGN AND METHODS A total of 212 women with a singleton pregnancy, 132 with NGT and 80 with GDM, and their offspring were studied. Maternal blood was o...

  20. Chemoenzymatic synthesis of sialylated glycopeptides derived from mucins and T-cell stimulating peptides.

    Science.gov (United States)

    George, S K; Schwientek, T; Holm, B; Reis, C A; Clausen, H; Kihlberg, J

    2001-11-14

    The Tn, T, sialyl-Tn, and 2,3-sialyl-T antigens are tumor-associated carbohydrate antigens expressed on mucins in epithelial cancers, such as those affecting the breast, ovary, stomach, and colon. Glycopeptides carrying these antigens are of interest for development of cancer vaccines and a short, chemoenzymatic strategy for their synthesis is reported. Building blocks corresponding to the Tn (GalNAc alpha-Ser/Thr) and T [Gal beta(1-->3)GalNAc alpha-Ser/Thr] antigens, which are relatively easy to obtain by chemical synthesis, were prepared and then used in the synthesis of glycopeptides on the solid phase. Introduction of sialic acid to give the sialyl-Tn [Neu5Ac alpha(2-->6)GalNAc alpha-Ser/Thr] and 2,3-sialyl-T [Neu5Ac alpha(2-->3)Gal beta(1-->3)GalNAc alpha-Ser/Thr] antigens is difficult when performed chemically at the building block level. Sialylation was therefore carried out with recombinant sialyltransferases in solution after cleavage of the Tn and T glycopeptides from the solid phase. In the same manner, the core 2 trisaccharide [Gal beta 1-->3(GlcNAc beta 1-->6)GalNAc] was incorporated in glycopeptides containing the T antigen by using a recombinant N-acetylglucosaminyltransferase. The outlined chemoenzymatic approach was applied to glycopeptides from the tandem repeat domain of the mucin MUC1, as well as to neoglycosylated derivatives of a T cell stimulating viral peptide. PMID:11697954

  1. APOBEC3G impairs the multimerization of the HIV-1 Vif protein in living cells.

    Science.gov (United States)

    Batisse, Julien; Guerrero, Santiago Xavier; Bernacchi, Serena; Richert, Ludovic; Godet, Julien; Goldschmidt, Valérie; Mély, Yves; Marquet, Roland; de Rocquigny, Hugues; Paillart, Jean-Christophe

    2013-06-01

    The HIV-1 viral infectivity factor (Vif) is a small basic protein essential for viral fitness and pathogenicity. Vif allows productive infection in nonpermissive cells, including most natural HIV-1 target cells, by counteracting the cellular cytosine deaminases APOBEC3G (apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3G [A3G]) and A3F. Vif is also associated with the viral assembly complex and packaged into viral particles through interactions with the viral genomic RNA and the nucleocapsid domain of Pr55(Gag). Recently, we showed that oligomerization of Vif into high-molecular-mass complexes induces Vif folding and influences its binding to high-affinity RNA binding sites present in the HIV genomic RNA. To get further insight into the role of Vif multimerization in viral assembly and A3G repression, we used fluorescence lifetime imaging microscopy (FLIM)- and fluorescence resonance energy transfer (FRET)-based assays to investigate Vif-Vif interactions in living cells. By using two N-terminally tagged Vif proteins, we show that Vif-Vif interactions occur in living cells. This oligomerization is strongly reduced when the putative Vif multimerization domain ((161)PPLP(164)) is mutated, indicating that this domain is crucial, but that regions outside this motif also participate in Vif oligomerization. When coexpressed together with Pr55(Gag), Vif is largely relocated to the cell membrane, where Vif oligomerization also occurs. Interestingly, wild-type A3G strongly interferes with Vif multimerization, contrary to an A3G mutant that does not bind to Vif. These findings confirm that Vif oligomerization occurs in living cells partly through its C-terminal motif and suggest that A3G may target and perturb the Vif oligomerization state to limit its functions in the cell. PMID:23576497

  2. The Bryopsis hypnoides plastid genome: multimeric forms and complete nucleotide sequence.

    Directory of Open Access Journals (Sweden)

    Fang Lü

    Full Text Available BACKGROUND: Bryopsis hypnoides Lamouroux is a siphonous green alga, and its extruded protoplasm can aggregate spontaneously in seawater and develop into mature individuals. The chloroplast of B. hypnoides is the biggest organelle in the cell and shows strong autonomy. To better understand this organelle, we sequenced and analyzed the chloroplast genome of this green alga. PRINCIPAL FINDINGS: A total of 111 functional genes, including 69 potential protein-coding genes, 5 ribosomal RNA genes, and 37 tRNA genes were identified. The genome size (153,429 bp, arrangement, and inverted-repeat (IR-lacking structure of the B. hypnoides chloroplast DNA (cpDNA closely resembles that of Chlorella vulgaris. Furthermore, our cytogenomic investigations using pulsed-field gel electrophoresis (PFGE and southern blotting methods showed that the B. hypnoides cpDNA had multimeric forms, including monomer, dimer, trimer, tetramer, and even higher multimers, which is similar to the higher order organization observed previously for higher plant cpDNA. The relative amounts of the four multimeric cpDNA forms were estimated to be about 1, 1/2, 1/4, and 1/8 based on molecular hybridization analysis. Phylogenetic analyses based on a concatenated alignment of chloroplast protein sequences suggested that B. hypnoides is sister to all Chlorophyceae and this placement received moderate support. CONCLUSION: All of the results suggest that the autonomy of the chloroplasts of B. hypnoides has little to do with the size and gene content of the cpDNA, and the IR-lacking structure of the chloroplasts indirectly demonstrated that the multimeric molecules might result from the random cleavage and fusion of replication intermediates instead of recombinational events.

  3. Monomeric, dimeric and multimeric system of RGD peptides radiolabeled with 177Lu for tumors therapy that expressing αβ integrin s

    International Nuclear Information System (INIS)

    The conjugation of peptides to gold nanoparticles (AuNPs) produces biocompatible and stable multimeric systems with target-specific molecular recognition. Peptides based on the cyclic Arg-Gly-Asp (RGD) sequence have been reported as high affinity agents for the α(v)β(3) and α(v)β(5) integrin. The aim of this research was to prepare a multimeric system of 177Lu-labeled gold nanoparticles conjugated to c[RGDfK(C)] [cyclo(Arg-Gly-Asp-Phe-Lys(Cys)] peptides and to compare the radiation absorbed dose with that of 177Lu-labeled monomeric and dimeric RGD peptides to α(v)β(3) integrin-positive U87MG tumors in mice, as well as, evaluate the in vitro potential 177Lu-AuNP-c[RGDfK(C)] as a plasmonic photothermal therapy and targeted radiotherapy system in MCF7 breast cancer cells. DOTA-GGC (1,4,7,10-tetraaza cyclododecane-N,N,N-tetraacetic-Gly-Gly-Cys) and c[RGDfK(C)] peptides were synthesized and conjugated to AuNPs by the spontaneous reaction of the thiol groups. Tem, UV-Vis, XP S, Raman and Far-IR spectroscopy techniques demonstrated that AuNPs were functionalized with the peptides. To obtain 177Lu-AuNP-c[RGDfK(C)], the 177Lu-DOTA-GGC radio peptide was first prepared and added to a solution of AuNPs followed by c[RGDfK(C)] (25 μL, 5 μM) at 18 grades C for 15 min. 177Lu-DOTA-GGC, 177Lu- DOTA-cRGDfK and 177Lu-DOTA-E-c(RGDfK)2 were prepared by adding 177LuCl3 (370 MBq) to 5 μL (1 mg/ml) of the DOTA derivative diluted with 50 μL of 1 M acetate buffer at ph 5. The mixture was incubated at 90 grades C in a block heater for 30 min. Radiochemical purity was determined by ultrafiltration and HPLC analyses. After laser irradiation, the presence of c[RGDfK(C)]-AuNP in cells caused a significant increase in the temperature of the medium (50.5 grades C, compared to 40.3 grades C without AuNPs) resulting in a significant decrease in MCF7 cell viability down to 9 %. After treatment with 177Lu-AuNP-c[RGDfK(C)], the MCF7 cell proliferation was significantly inhibited. Biokinetic

  4. An aerogel obtained from chemo-enzymatically oxidized fenugreek galactomannans as a versatile delivery system.

    Science.gov (United States)

    Rossi, Bianca; Campia, Paola; Merlini, Luca; Brasca, Milena; Pastori, Nadia; Farris, Stefano; Melone, Lucio; Punta, Carlo; Galante, Yves M

    2016-06-25

    We describe a new aerogel obtained from laccase-oxidized galactomannans of the leguminous plant fenugreek (Trigonella foenum-graecum) and suggest its potential practical use. Laccase/TEMPO oxidation of fenugreek in aqueous solution caused a viscosity increase of over 15-fold. A structured, elastic, stable hydrogel was generated, due to formation of carbonyl groups from primary OH of galactose side units and subsequent establishment of hemiacetalic bonds with available free hydroxyl groups. Upon lyophilization of this hydrogel, a water-insoluble aerogel was obtained (EOLFG), capable of uptaking aqueous or organic solvents over 20 times its own weight. The material was characterized by scanning electron microscopy, FT-IR, elemental analysis and (13)C CP-MAS NMR spectroscopy and its mechanical properties were investigated. To test the EOLFG as a delivery system, the anti-microbial enzyme lysozyme was used as model active principle. Lysozyme was added before or after formation of the aerogel, entrapped or absorbed in the gel, retained and released in active form, as proven by its hydrolytic glycosidase activity on lyophilized Micrococcus lysodeikticus cells wall peptidoglycans. This new biomaterial, composed of a chemo-enzymatically modified plant polysaccharide, might represent a versatile, biocompatible "delivery system" of active principles in food and non-food products. PMID:27083827

  5. Chemoenzymatic synthesis and antileukemic activity of novel C9- and C14-functionalized parthenolide analogs.

    Science.gov (United States)

    Tyagi, Vikas; Alwaseem, Hanan; O'Dwyer, Kristen M; Ponder, Jessica; Li, Qi Ying; Jordan, Craig T; Fasan, Rudi

    2016-09-01

    Parthenolide is a naturally occurring terpene with promising anticancer properties, particularly in the context of acute myeloid leukemia (AML). Optimization of this natural product has been challenged by limited opportunities for the late-stage functionalization of this molecule without affecting the pharmacologically important α-methylene-γ-lactone moiety. Here, we report the further development and application of a chemoenzymatic strategy to afford a series of new analogs of parthenolide functionalized at the aliphatic positions C9 and C14. Several of these compounds were determined to be able to kill leukemia cells and patient-derived primary AML specimens with improved activity compared to parthenolide, exhibiting LC50 values in the low micromolar range. These studies demonstrate that different O-H functionalization chemistries can be applied to elaborate the parthenolide scaffold and that modifications at the C9 or C14 position can effectively enhance the antileukemic properties of this natural product. The C9-functionalized analogs 22a and 25b were identified as the most interesting compounds in terms of antileukemic potency and selectivity toward AML versus healthy blood cells. PMID:27396927

  6. Highly efficient preparation of sphingoid bases from glucosylceramides by chemoenzymatic method.

    Science.gov (United States)

    Gowda, Siddabasave Gowda B; Usuki, Seigo; Hammam, Mostafa A S; Murai, Yuta; Igarashi, Yasuyuki; Monde, Kenji

    2016-02-01

    Sphingoid base derivatives have attracted increasing attention as promising chemotherapeutic candidates against lifestyle diseases such as diabetes and cancer. Natural sphingoid bases can be a potential resource instead of those derived by time-consuming total organic synthesis. In particular, glucosylceramides (GlcCers) in food plants are enriched sources of sphingoid bases, differing from those of animals. Several chemical methodologies to transform GlcCers to sphingoid bases have already investigated; however, these conventional methods using acid or alkaline hydrolysis are not efficient due to poor reaction yield, producing complex by-products and resulting in separation problems. In this study, an extremely efficient and practical chemoenzymatic transformation method has been developed using microwave-enhanced butanolysis of GlcCers and a large amount of readily available almond β-glucosidase for its deglycosylation reaction of lysoGlcCers. The method is superior to conventional acid/base hydrolysis methods in its rapidity and its reaction cleanness (no isomerization, no rearrangement) with excellent overall yield. PMID:26667669

  7. Asymmetric chemoenzymatic synthesis of miconazole and econazole enantiomers. The importance of chirality in their biological evaluation.

    Science.gov (United States)

    Mangas-Sánchez, Juan; Busto, Eduardo; Gotor-Fernández, Vicente; Malpartida, Francisco; Gotor, Vicente

    2011-04-01

    A simple and novel chemoenzymatic route has been applied for the first time in the synthesis of miconazole and econazole single enantiomers. Lipases and oxidoreductases have been tested in stereoselective processes; the best results were attained with oxidoreductases for the introduction of chirality in an adequate intermediate. The behaviors of a series of ketones and racemic alcohols in bioreductions and acetylation procedures, respectively, have been investigated; the best results were found with alcohol dehydrogenases A and T, which allowed the production of (R)-2-chloro-1-(2,4-dichlorophenyl)ethanol in enantiopure form under very mild reaction conditions. Final chemical modifications have been performed in order to isolate the target fungicides miconazole and econazole both as racemates and as single enantiomers. Biological evaluation of the racemates and single enantiomers has shown remarkable differences against the growth of several microorganisms; while (R)-miconazole seemed to account for most of the biological activity of racemic miconazole on all the strains tested, both enantiomers of econazole showed considerable biological activities. In this manner, (R)-econazole showed higher values against Candida krusei , while higher values were observed for (S)-econazole against Cryptococcus neoformans, Penicillium chrysogenum, and Aspergillus niger. PMID:21384803

  8. Automated chemoenzymatic synthesis of no-carrier-added [carbonyl-11C]propionyl L-carnitine for pharmacokinetic studies

    International Nuclear Information System (INIS)

    Propionyl-L-carnitine (PLC) is under development as a therapeutic for the treatment of peripheral artery disease, coronary heart disease and chronic heart failure. Three methods were examined for labelling PLC in its propionyl group with positron-emitting carbon-11 (t1/2 = 20.3 min), one chemical and two chemoenzymatic. The former was based on the preparation of [11C]propionyl chloride as labelling agent via 11C-carboxylation of ethylmagnesium bromide with cyclotron-produced [11C]carbon dioxide and subsequent chlorination. Reaction of carrier-added [11C]propionyl chloride with L-carnitine in trifluoroacetic acid gave [11C]PLC in 12% radiochemical yield (decay-corrected) from cyclotron-produced [11C]carbon dioxide. However, the radiosynthesis was unsuccessful at the no-carrier added (NCA) level of specific radioactivity. [11C]Propionate, as a radioactive precursor for chemoenzymatic routes, was prepared via carboxylation of ethylmagnesium bromide with [11C]carbon dioxide and hydrolysis. NCA [11C]PLC was prepared in 68 min in 14% radiochemical yield (decay-corrected) from [11C]propionate via sequential conversions catalysed by acetate kinase, phosphotransacetylase and carnitine acetyltransferase. A superior chemoenzymatic synthesis of NCA [11C]PLC was developed, based on the use of a novel supported Grignard reagent for the synthesis of [11C]propionate and conversions by S-acetyl-CoA synthetase and carnitine acetyltransferase. This gave an overall radiochemical yield of 30-48% (decay-corrected). This synthesis was automated for radiation safety and provides pure NCA [11C]PLC in high radioactivities ready for intravenous administration within 25 min from radionuclide production. The [11C]PLC is suitable for pharmacokinetic studies in human subjects with PET and the elucidation of the fate of the propionyl group of PLC in vivo. (Author)

  9. A template-based mnemonic for monoamine oxidase (MAO-N) catalyzed reactions and its application to the chemo-enzymatic deracemisation of the alkaloid (+/-)-crispine A.

    Science.gov (United States)

    Bailey, Kevin R; Ellis, Andrew J; Reiss, Renate; Snape, Timothy J; Turner, Nicholas J

    2007-09-21

    A template-based mnemonic has been developed for the enzyme monoamine oxidase from Aspergillus niger and has been used to successfully identify the alkaloid (+/-)-crispine A as a target for chemo-enzymatic deracemisation yielding the biologically active (R)-enantiomer in 97% e.e. PMID:17728879

  10. Transketolase(TK) catalyzed C-C Bond Formation:Chemoenzymatic Synthesis of 2-keto-3-deoxy-D-arabino- Heptulosonic Acid (DAH) and Analogues

    Czech Academy of Sciences Publication Activity Database

    Crestia, D.; Hecquet, L.; Bolte, J.; Demuynck, C.; Tóthová, Andrea; Martínková, Ludmila; Křen, Vladimír

    Darmstadt, 2001. s. 294. [International Symposium on Biocatalysis and Biotransformation /5./. 02.09.2001-07.09.2001, Darmstadt] R&D Projects: GA ČR GA524/00/1275 Keywords : chemoenzymatic * metabolic * aminoacids Subject RIV: EE - Microbiology, Virology

  11. Chemo-enzymatic modification of poly-N-acetyllactosamine (LacNAc) oligomers and N,N-diacetyllactosamine (LacDiNAc) based on galactose oxidase treatment

    Czech Academy of Sciences Publication Activity Database

    Kupper, E. Ch.; Rosencrantz, R. R.; Henßen, B.; Pelantová, Helena; Thönes, S.; Drozdová, Anna; Křen, Vladimír; Elling, L.

    2012-01-01

    Roč. 8, MAY 9 2012 (2012), s. 712-725. ISSN 1860-5397 R&D Projects: GA MŠk OC09045 Keywords : chemo-enzymatic synthesis * galactose oxidase * glycosyltransferase Subject RIV: CE - Biochemistry Impact factor: 2.801, year: 2012

  12. Chemoenzymatic synthesis of the bacterial polysaccharide repeating unit undecaprenyl pyrophosphate and its analogs.

    Science.gov (United States)

    Li, Lei; Woodward, Robert L; Han, Weiqing; Qu, Jingyao; Song, Jing; Ma, Cheng; Wang, Peng G

    2016-07-01

    Polysaccharides are essential and immunologically relevant components of bacterial cell walls. These biomolecules can be found covalently attached to lipids (e.g., O-polysaccharide (PS) contains undecaprenyl and lipopolysaccharide (LPS) contains lipid A) or noncovalently associated with cell wells (e.g., capsular PS (CPS)). Although extensive genetic studies have indicated that the Wzy-dependent biosynthetic pathway is primarily responsible for producing such polysaccharides, in vitro biochemical studies are needed to determine, for example, which gene product is responsible for catalyzing each step in the pathway, and to reveal molecular details about the Wzx translocase, Wzy polymerase and O-PS chain-length determinant. Many of these biochemical studies require access to a structurally well-defined PS repeating unit undecaprenyl pyrophosphate (RU-PP-Und), the key building block in this pathway. We describe herein the chemoenzymatic synthesis of Escherichia coli (serotype O157) RU-PP-Und. This involves (i) chemical synthesis of precursor N-acetyl-D-galactosamine (GalNAc)-PP-Und (2 weeks) and (ii) enzymatic extension of the precursor to produce RU-PP-Und (2 weeks). Undecaprenyl phosphate and peracetylated GalNAc-1-phosphate are prepared from commercially available undecaprenol and peracetylated GalNAc. The chemical coupling of these two products, followed by structural confirmation (mass spectrometry and NMR) and deprotection, generates GalNAc-PP-Und. This compound is then sequentially modified by enzymes in the E. coli serotype O157 (E. coli O157) O-PS biosynthetic pathway. Three glycosyltransferases (GTs) are involved (WbdN, WbdO and WbdP) and they transfer glucose (Glc), L-fucose (L-Fuc) and N-acetylperosamine (PerNAc) onto GalNAc-PP-Und to form the intact RU-PP-Und in a stepwise manner. Final compounds and intermediates are confirmed by mass spectrometry. The procedure can be adapted to the synthesis of analogs with different PS or lipid moieties. PMID:27336706

  13. A self-compartmentalizing hexamer serine protease from Pyrococcus horikoshii: substrate selection achieved through multimerization.

    Science.gov (United States)

    Menyhárd, Dóra K; Kiss-Szemán, Anna; Tichy-Rács, Éva; Hornung, Balázs; Rádi, Krisztina; Szeltner, Zoltán; Domokos, Klarissza; Szamosi, Ilona; Náray-Szabó, Gábor; Polgár, László; Harmat, Veronika

    2013-06-14

    Oligopeptidases impose a size limitation on their substrates, the mechanism of which has long been under debate. Here we present the structure of a hexameric serine protease, an oligopeptidase from Pyrococcus horikoshii (PhAAP), revealing a complex, self-compartmentalized inner space, where substrates may access the monomer active sites passing through a double-gated "check-in" system, first passing through a pore on the hexamer surface and then turning to enter through an even smaller opening at the monomers' domain interface. This substrate screening strategy is unique within the family. We found that among oligopeptidases, a residue of the catalytic apparatus is positioned near an amylogenic β-edge, which needs to be protected to prevent aggregation, and we found that different oligopeptidases use different strategies to achieve such an end. We propose that self-assembly within the family results in characteristically different substrate selection mechanisms coupled to different multimerization states. PMID:23632025

  14. The DynDom3D Webserver for the Analysis of Domain Movements in Multimeric Proteins.

    Science.gov (United States)

    Girdlestone, Christopher; Hayward, Steven

    2016-01-01

    DynDom3D is a program for the analysis of domain movements in multimeric proteins. Its inputs are two structure files that indicate a possible domain movement, but the onus has been on the user to process the files so that there is the necessary one-to-one equivalence between atoms in the two atom lists. This is often a prohibitive task to carry out manually, which has limited the application of DynDom3D. Here we report on a webserver with a preprocessor that automatically creates an equivalence between atoms using sequence alignment methods. The processed structure files are passed to DynDom3D and the results are presented on a webpage that includes molecular graphics for easy visualization. PMID:26540459

  15. Kinetic Analysis of the Guanine Nucleotide Exchange Activity of TRAPP, a Multimeric Ypt1p Exchange Factor

    OpenAIRE

    Chin, Harvey F.; Cai, Yiying; Menon, Shekar; Ferro-Novick, Susan; Reinisch, Karin M; De La Cruz, Enrique M.

    2009-01-01

    The TRAPP complexes, large multimeric assemblies that function in membrane traffic, are guanine nucleotide exchange factors (GEF) that activate the Rab GTPase Ypt1p. Here we measured the rate and equilibrium constants that define the interaction of Ypt1p with guanine nucleotide (GDP and GTP/GMPPNP) and the core TRAPP subunits required for GEF activity. These parameters allowed us to identify the kinetic and thermodynamic basis by which TRAPP catalyzes nucleotide exchange from Ypt1p. Nucleotid...

  16. Essential roles of insulin, AMPK signaling and lysyl and prolyl hydroxylases in the biosynthesis and multimerization of adiponectin

    OpenAIRE

    Zhang L, Li M, Corcoran M, Zhang S, Cooper GJS

    2015-01-01

    Post-translational modifications (PTMs) of the adiponectin molecule are essential for its full bioactivity, and defects in PTMs leading to its defective production and multimerization have been linked to the mechanisms of insulin resistance, obesity, and type-2 diabetes. Here we observed that, in differentiated 3T3-L1 adipocytes, decreased insulin signaling caused by blocking of insulin receptors (InsR) with an anti-InsR blocking antibody, increased rates of adiponectin secretion, whereas con...

  17. In Silico Structure and Sequence Analysis of Bacterial Porins and Specific Diffusion Channels for Hydrophilic Molecules: Conservation, Multimericity and Multifunctionality

    Science.gov (United States)

    Vollan, Hilde S.; Tannæs, Tone; Vriend, Gert; Bukholm, Geir

    2016-01-01

    Diffusion channels are involved in the selective uptake of nutrients and form the largest outer membrane protein (OMP) family in Gram-negative bacteria. Differences in pore size and amino acid composition contribute to the specificity. Structure-based multiple sequence alignments shed light on the structure-function relations for all eight subclasses. Entropy-variability analysis results are correlated to known structural and functional aspects, such as structural integrity, multimericity, specificity and biological niche adaptation. The high mutation rate in their surface-exposed loops is likely an important mechanism for host immune system evasion. Multiple sequence alignments for each subclass revealed conserved residue positions that are involved in substrate recognition and specificity. An analysis of monomeric protein channels revealed particular sequence patterns of amino acids that were observed in other classes at multimeric interfaces. This adds to the emerging evidence that all members of the family exist in a multimeric state. Our findings are important for understanding the role of members of this family in a wide range of bacterial processes, including bacterial food uptake, survival and adaptation mechanisms. PMID:27110766

  18. Nucleic acid binding properties and intermediates of HCV core protein multimerization in Pichia pastoris

    International Nuclear Information System (INIS)

    Little is known about the in vivo assembly pathway or structure of the hepatitis C virus nucleocapsid. In this work the intermediates of HCcAg multimerization in Pichia pastoris cells and the nucleic acid binding properties of structured nucleocapsid-like particles (NLPs) were studied. Extensive cross-linking was observed for HCcAg after glutaraldehyde treatment. Data suggest that HCcAg exists in dimeric forms probably representing P21-P21, P21-P23, and P23-P23 dimers. In addition, the presence of HCcAg species that might represent trimers and multimers was observed. After sucrose equilibrium density gradient purification and nuclease digestion, NLPs were shown to contain both RNA and DNA molecules. Finally, the analysis by electron microscopy indicated that native NLPs were resistant to nuclease treatment. These results indicated that HCcAg assembles through dimers, trimers, and multimers' intermediates into capsids in P. pastoris cells. Assembly of NLPs in its natural environment might confer stability to these particles by adopting a compact structure

  19. Synthesis of α,β-unsaturated esters via a chemo-enzymatic chain elongation approach by combining carboxylic acid reduction and Wittig reaction

    OpenAIRE

    Yitao Duan; Peiyuan Yao; Yuncheng Du; Jinhui Feng; Qiaqing Wu; Dunming Zhu

    2015-01-01

    α,β-Unsaturated esters are versatile building blocks for organic synthesis and of significant importance for industrial applications. A great variety of synthetic methods have been developed, and quite a number of them use aldehydes as precursors. Herein we report a chemo-enzymatic chain elongation approach to access α,β-unsaturated esters by combining an enzymatic carboxylic acid reduction and Wittig reaction. Recently, we have found that Mycobacterium sp. was able to reduce phenylacetic aci...

  20. Whole Pichia pastoris yeast expressing measles virus nucleoprotein as a production and delivery system to multimerize Plasmodium antigens.

    Directory of Open Access Journals (Sweden)

    Daria Jacob

    Full Text Available Yeasts are largely used as bioreactors for vaccine production. Usually, antigens are produced in yeast then purified and mixed with adjuvants before immunization. However, the purification costs and the safety concerns recently raised by the use of new adjuvants argue for alternative strategies. To this end, the use of whole yeast as both production and delivery system appears attractive. Here, we evaluated Pichia pastoris yeast as an alternative vaccine production and delivery system for the circumsporozoite protein (CS of Plasmodium, the etiologic agent of malaria. The CS protein from Plasmodium berghei (Pb was selected given the availability of the stringent C57Bl/6 mouse model of infection by Pb sporozoites, allowing the evaluation of vaccine efficacy in vivo. PbCS was multimerized by fusion to the measles virus (MV nucleoprotein (N known to auto-assemble in yeast in large-size ribonucleoprotein rods (RNPs. Expressed in P. pastoris, the N-PbCS protein generated highly multimeric and heterogenic RNPs bearing PbCS on their surface. Electron microscopy and immunofluorescence analyses revealed the shape of these RNPs and their localization in peripheral cytoplasmic inclusions. Subcutaneous immunization of C57Bl/6 mice with heat-inactivated whole P. pastoris expressing N-PbCS RNPs provided significant reduction of parasitemia after intradermal challenge with a high dose of parasites. Thus, in the absence of accessory adjuvants, a very low amount of PbCS expressed in whole yeast significantly decreased clinical damages associated with Pb infection in a highly stringent challenge model, providing a proof of concept of the intrinsic adjuvancy of this vaccine strategy. In addition to PbCS multimerization, the N protein contributed by itself to parasitemia delay and long-term mice survival. In the future, mixtures of whole recombinant yeasts expressing relevant Plasmodium antigens would provide a multivalent formulation applicable for antigen

  1. Importance of the proline-rich multimerization domain on the oligomerization and nucleic acid binding properties of HIV-1 Vif

    OpenAIRE

    Bernacchi, Serena; Mercenne, Gaëlle; Tournaire, Clémence; Marquet, Roland; Paillart, Jean-Christophe

    2010-01-01

    The HIV-1 viral infectivity factor (Vif) is required for productive infection of non-permissive cells, including most natural HIV-1 targets, where it counteracts the antiviral activities of the cellular cytosine deaminases APOBEC-3G (A3G) and A3F. Vif is a multimeric protein and the conserved proline-rich domain 161PPLP164 regulating Vif oligomerization is crucial for its function and viral infectivity. Here, we expressed and purified wild-type Vif and a mutant protein in which alanines were ...

  2. Multimerization of the cytoplasmic domain of syndecan-4 is required for its ability to activate protein kinase C

    DEFF Research Database (Denmark)

    Oh, E S; Woods, A; Couchman, J R

    1997-01-01

    corresponding to the central region of syndecan-4 cytoplasmic domain (4V) also oligomerizes. The degree of oligomerization correlates with the previously reported ability to bind protein kinase C (PKC) and regulate its activity. Only multimeric recombinant syndecan-4 core protein, but not the monomeric protein......, potentiated the activity of PKCalpha, and only oligomeric syndecan-4 cytoplasmic peptides were active. Changes in peptide sequence caused parallel loss of stable oligomeric status and ability to regulate a mixture of PKCalphabetagamma activity. A synthetic peptide encompassing the whole cytoplasmic domain of...

  3. Automated chemoenzymatic synthesis of no-carrier-added [carbonyl-{sup 11}C]propionyl L-carnitine for pharmacokinetic studies

    Energy Technology Data Exchange (ETDEWEB)

    Davenport, R.J.; Pike, V.W.; Dowsett, K.; Turton, D.R.; Poole, K. [Hammersmith Hospital, London (United Kingdom). MRC Cyclotron Unit

    1997-07-30

    Propionyl-L-carnitine (PLC) is under development as a therapeutic for the treatment of peripheral artery disease, coronary heart disease and chronic heart failure. Three methods were examined for labelling PLC in its propionyl group with positron-emitting carbon-11 (t{sub 1/2} = 20.3 min), one chemical and two chemoenzymatic. The former was based on the preparation of [{sup 11}C]propionyl chloride as labelling agent via {sup 11}C-carboxylation of ethylmagnesium bromide with cyclotron-produced [{sup 11}C]carbon dioxide and subsequent chlorination. Reaction of carrier-added [{sup 11}C]propionyl chloride with L-carnitine in trifluoroacetic acid gave [{sup 11}C]PLC in 12% radiochemical yield (decay-corrected) from cyclotron-produced [{sup 11}C]carbon dioxide. However, the radiosynthesis was unsuccessful at the no-carrier added (NCA) level of specific radioactivity. [{sup 11}C]Propionate, as a radioactive precursor for chemoenzymatic routes, was prepared via carboxylation of ethylmagnesium bromide with [{sup 11}C]carbon dioxide and hydrolysis. NCA [{sup 11}C]PLC was prepared in 68 min in 14% radiochemical yield (decay-corrected) from [{sup 11}C]propionate via sequential conversions catalysed by acetate kinase, phosphotransacetylase and carnitine acetyltransferase. A superior chemoenzymatic synthesis of NCA [{sup 11}C]PLC was developed, based on the use of a novel supported Grignard reagent for the synthesis of [{sup 11}C]propionate and conversions by S-acetyl-CoA synthetase and carnitine acetyltransferase. This gave an overall radiochemical yield of 30-48% (decay-corrected). This synthesis was automated for radiation safety and provides pure NCA [{sup 11}C]PLC in high radioactivities ready for intravenous administration within 25 min from radionuclide production. The [{sup 11}C]PLC is suitable for pharmacokinetic studies in human subjects with PET and the elucidation of the fate of the propionyl group of PLC in vivo. (Author).

  4. Chemo-enzymatic synthesis of a series of 2,4-syn-functionalized (S)-glutamate analogues: new insight into the structure-activity relation of ionotropic glutamate receptor subtypes 5, 6, and 7

    DEFF Research Database (Denmark)

    Sagot, Emanuelle; Pickering, Darryl S; Pu, Xiaosui;

    2008-01-01

    ( S)-Glutamic acid (Glu) is the major excitatory neurotransmitter in the central nervous system (CNS) activating the plethora of ionotropic Glu receptors (iGluRs) and metabotropic Glu receptors (mGluRs). In this paper, we present a chemo-enzymatic strategy for the enantioselective synthesis of fi...

  5. GPIHBP1 Missense Mutations Often Cause Multimerization of GPIHBP1 and Thereby Prevent Lipoprotein Lipase Binding

    DEFF Research Database (Denmark)

    Beigneux, Anne P; Fong, Loren G; Bensadoun, Andre;

    2015-01-01

    understand mechanisms by which GPIHBP1 mutations prevent LPL binding and lead to chylomicronemia. Methods and Results: We expressed mutant forms of GPIHBP1 in Chinese hamster ovary cells, rat and human endothelial cells, and Drosophila S2 cells. In each expression system, mutation of cysteines in GPIHBP1's......Rationale: GPIHBP1, a GPI-anchored protein of capillary endothelial cells, binds lipoprotein lipase (LPL) in the subendothelial spaces and shuttles it to the capillary lumen. GPIHBP1 missense mutations that interfere with LPL binding cause familial chylomicronemia. Objective: We sought to...... Ly6 domain (including mutants identified in chylomicronemia patients) led to the formation of disulfide-linked dimers and multimers. GPIHBP1 dimerization/multimerization was not unique to cysteine mutations; mutations in other amino acid residues, including several associated with chylomicronemia...

  6. Total adiponectin and adiponectin multimeric complexes in relation to weight loss-induced improvements in insulin sensitivity in obese women

    DEFF Research Database (Denmark)

    Polak, J.; Kovacova, Z.; Holst, C.;

    2008-01-01

    AIM: Adiponectin increases insulin sensitivity, protects arterial walls against atherosclerosis, and regulates glucose metabolism, and is decreased in obese, insulin resistant, and type 2 diabetic patients. Adiponectin circulates in plasma as high, medium, and low molecular weight forms (HMW, MMW......, and LMW). The HMW form was suggested to be closely associated with insulin sensitivity. This study investigated whether diet-induced changes in insulin sensitivity were associated with changes in adiponectin multimeric complexes. SUBJECTS: Twenty obese women with highest and twenty obese women with...... kcal/d less than energy requirements). Plasma HMW, MMW, and LMW forms of adiponectin were quantified using Western blot method. RESULTS: LCD induced comparable weight reduction in responders and non-responders by 8.2 and 7.6 kg. Homeostasis model assessment insulin resistance index decreased by 48...

  7. Synthesis of α,β-unsaturated esters via a chemo-enzymatic chain elongation approach by combining carboxylic acid reduction and Wittig reaction

    Directory of Open Access Journals (Sweden)

    Yitao Duan

    2015-11-01

    Full Text Available α,β-Unsaturated esters are versatile building blocks for organic synthesis and of significant importance for industrial applications. A great variety of synthetic methods have been developed, and quite a number of them use aldehydes as precursors. Herein we report a chemo-enzymatic chain elongation approach to access α,β-unsaturated esters by combining an enzymatic carboxylic acid reduction and Wittig reaction. Recently, we have found that Mycobacterium sp. was able to reduce phenylacetic acid (1a to 2-phenyl-1-ethanol (1c and two sequences in the Mycobacterium sp. genome had high identity with the carboxylic acid reductase (CAR gene from Nocardia iowensis. These two putative CAR genes were cloned, overexpressed in E. coli and one of two proteins could reduce 1a. The recombinant CAR was purified and characterized. The enzyme exhibited high activity toward a variety of aromatic and aliphatic carboxylic acids, including ibuprofen. The Mycobacterium CAR catalyzed carboxylic acid reduction to give aldehydes, followed by a Wittig reaction to afford the products α,β-unsaturated esters with extension of two carbon atoms, demonstrating a new chemo-enzymatic method for the synthesis of these important compounds.

  8. Synthesis of α,β-unsaturated esters via a chemo-enzymatic chain elongation approach by combining carboxylic acid reduction and Wittig reaction.

    Science.gov (United States)

    Duan, Yitao; Yao, Peiyuan; Du, Yuncheng; Feng, Jinhui; Wu, Qiaqing; Zhu, Dunming

    2015-01-01

    α,β-Unsaturated esters are versatile building blocks for organic synthesis and of significant importance for industrial applications. A great variety of synthetic methods have been developed, and quite a number of them use aldehydes as precursors. Herein we report a chemo-enzymatic chain elongation approach to access α,β-unsaturated esters by combining an enzymatic carboxylic acid reduction and Wittig reaction. Recently, we have found that Mycobacterium sp. was able to reduce phenylacetic acid (1a) to 2-phenyl-1-ethanol (1c) and two sequences in the Mycobacterium sp. genome had high identity with the carboxylic acid reductase (CAR) gene from Nocardia iowensis. These two putative CAR genes were cloned, overexpressed in E. coli and one of two proteins could reduce 1a. The recombinant CAR was purified and characterized. The enzyme exhibited high activity toward a variety of aromatic and aliphatic carboxylic acids, including ibuprofen. The Mycobacterium CAR catalyzed carboxylic acid reduction to give aldehydes, followed by a Wittig reaction to afford the products α,β-unsaturated esters with extension of two carbon atoms, demonstrating a new chemo-enzymatic method for the synthesis of these important compounds. PMID:26664647

  9. Multimeric C9 within C5b-9 deposits in unique locations in the cell wall of Salmonella typhimurium

    International Nuclear Information System (INIS)

    We have shown previously that multimeric C9 within C5b-9 (C9:C5b-8 greater than 3:1) is needed for killing of a rough strain of Escherichia coli. We now extend these studies using serum sensitive, rough (R) and serum resistant, wild type (WT) strains of Salmonella typhimurium as well as a mutant S. typhimurium strain (TS) with a temperature sensitive mutation in synthesis of keto-deoxy-octulosonate, a constituent within the deep core structure of Salmonella LPS. Both R and TS required multimeric C9 within C5b-9 to be killed. Addition at 37 degrees C of increasing inputs of C9 to TS or R bearing C5b-9 led to a dose-related increase in C9 binding and killing. In contrast, addition of high inputs of C9 to the same strains at 4 degrees C, a procedure that limits the C9:C5b-8 ratio to 1:1, resulted in low C9 binding and minimal killing. Bactericidal C5b-9 formed at 37 degrees C on R and TS with high inputs of C9 co-sedimented with the bacterial outer membrane on sucrose density gradient analysis. Non-bactericidal C5b-9 on R, WT, and TS co-sedimented near the inner membrane, despite the presumed lack of association between these constituents. Whereas 125I C9 within the non-bactericidal pools immunoprecipitate with anti-C5, 125I C9 within bactericidal pools did not immunoprecipitate with anti-C5, anti-C7, or anti-C9. These findings suggest that bactericidal C5b-9 may be deposited in a unique location or configuration within the bacterial cell wall

  10. COOH-terminal substitutions in the serpin C1 inhibitor that cause loop overinsertion and subsequent multimerization.

    Science.gov (United States)

    Eldering, E; Verpy, E; Roem, D; Meo, T; Tosi, M

    1995-02-10

    The region COOH-terminal to the reactive center loop is highly conserved in the serine protease inhibitor (serpin) family. We have studied the structural consequences of three substitutions (Val451-->Met, Phe455-->Ser, and Pro476-->Ser) found in this region of C1 inhibitor in patients suffering from hereditary angioedema. Equivalent substitutions have been described in alpha 1-antitrypsin and antithrombin III. The mutant C1 inhibitor proteins were only partially secreted upon transient transfection into COS-7 cells and were found to be dysfunctional. Immunoprecipitation of conditioned media demonstrated that in the intact, uncleaved form they all bind to a monoclonal antibody which recognizes specifically the protease-complexed or reactive center-cleaved normal C1 inhibitor. A second indication for an intrinsic conformational change was the increased thermostability compared to the normal protein. Furthermore, gel filtration studies showed that the Val451-->Met and Pro476-->Ser mutant proteins, and to a lesser extent Phe455-->Ser, were prone to spontaneous multimerization. Finally, a reduced susceptibility to reactive center cleavage by trypsin was observed for all three mutants, and the cleaved Val451-->Met and Pro476-->Ser mutants failed to adopt the conformation recognized by a cleavage-specific monoclonal antibody. Investigation of plasmas of patients with the Val451-->Met or Pro476-->Ser substitutions showed that these dysfunctional proteins circulate at low levels and are recognized by the complex-specific antibody. These results strongly indicate a conformational change as a result of these carboxylterminal substitutions, such that anchoring of the reactive center loop at the COOH-terminal side is not achieved properly. We propose that this results in overinsertion of the loop into beta-sheet A, which subsequently leads to multimerization. PMID:7852321

  11. Mechanisms of YidC-mediated Insertion and Assembly of Multimeric Membrane Protein Complexes

    OpenAIRE

    Kol, Stefan; Nouwen, Nico; Driessen, Arnold J. M.

    2008-01-01

    The YidC protein fulfills a dual and essential role in the assembly of inner membrane proteins in Escherichia coli. Besides interacting with transmembrane segments of newly synthesized membrane proteins that insert into the membrane via the SecYEG complex, YidC also functions as an independent membrane protein insertase and assists in membrane protein folding. Here, we discuss the mechanisms of YidC substrate recognition and membrane insertion with emphasis on its role in the assembly of mult...

  12. Analysis of the complexity of the multimeric structure of factor VIII related antigen/von Willebrand protein using a modified electrophoretic technique.

    OpenAIRE

    Enayat, M S; Hill, F G

    1983-01-01

    A method for multimeric analysis of factor VIII related antigen/von Willebrand protein is described. By modifying an existing method the technique has been simplified and optimised so that the different molecular forms of factor VIII related antigen and their triplet structure can be visualised. Clear differences can be seen between patterns in normals and type IIA von Willebrand's disease variants in that the latter lack high and intermediate multimers and also have a different configuration...

  13. Capsid protein VP4 of human rhinovirus induces membrane permeability by the formation of a size-selective multimeric pore.

    Directory of Open Access Journals (Sweden)

    Anusha Panjwani

    2014-08-01

    Full Text Available Non-enveloped viruses must deliver their viral genome across a cell membrane without the advantage of membrane fusion. The mechanisms used to achieve this remain poorly understood. Human rhinovirus, a frequent cause of the common cold, is a non-enveloped virus of the picornavirus family, which includes other significant pathogens such as poliovirus and foot-and-mouth disease virus. During picornavirus cell entry, the small myristoylated capsid protein VP4 is released from the virus, interacts with the cell membrane and is implicated in the delivery of the viral RNA genome into the cytoplasm to initiate replication. In this study, we have produced recombinant C-terminal histidine-tagged human rhinovirus VP4 and shown it can induce membrane permeability in liposome model membranes. Dextran size-exclusion studies, chemical crosslinking and electron microscopy demonstrated that VP4 forms a multimeric membrane pore, with a channel size consistent with transfer of the single-stranded RNA genome. The membrane permeability induced by recombinant VP4 was influenced by pH and was comparable to permeability induced by infectious virions. These findings present a molecular mechanism for the involvement of VP4 in cell entry and provide a model system which will facilitate exploration of VP4 as a novel antiviral target for the picornavirus family.

  14. Enhancing immunogenicity and transmission-blocking activity of malaria vaccines by fusing Pfs25 to IMX313 multimerization technology.

    Science.gov (United States)

    Li, Yuanyuan; Leneghan, Darren B; Miura, Kazutoyo; Nikolaeva, Daria; Brian, Iona J; Dicks, Matthew D J; Fyfe, Alex J; Zakutansky, Sarah E; de Cassan, Simone; Long, Carole A; Draper, Simon J; Hill, Adrian V S; Hill, Fergal; Biswas, Sumi

    2016-01-01

    Transmission-blocking vaccines (TBV) target the sexual-stages of the malaria parasite in the mosquito midgut and are widely considered to be an essential tool for malaria elimination. High-titer functional antibodies are required against target antigens to achieve effective transmission-blocking activity. We have fused Pfs25, the leading malaria TBV candidate antigen to IMX313, a molecular adjuvant and expressed it both in ChAd63 and MVA viral vectors and as a secreted protein-nanoparticle. Pfs25-IMX313 expressed from viral vectors or as a protein-nanoparticle is significantly more immunogenic and gives significantly better transmission-reducing activity than monomeric Pfs25. In addition, we demonstrate that the Pfs25-IMX313 protein-nanoparticle leads to a qualitatively improved antibody response in comparison to soluble Pfs25, as well as to significantly higher germinal centre (GC) responses. These results demonstrate that antigen multimerization using IMX313 is a very promising strategy to enhance antibody responses against Pfs25, and that Pfs25-IMX313 is a highly promising TBV candidate vaccine. PMID:26743316

  15. Importance of the proline-rich multimerization domain on the oligomerization and nucleic acid binding properties of HIV-1 Vif.

    Science.gov (United States)

    Bernacchi, Serena; Mercenne, Gaëlle; Tournaire, Clémence; Marquet, Roland; Paillart, Jean-Christophe

    2011-03-01

    The HIV-1 viral infectivity factor (Vif) is required for productive infection of non-permissive cells, including most natural HIV-1 targets, where it counteracts the antiviral activities of the cellular cytosine deaminases APOBEC-3G (A3G) and A3F. Vif is a multimeric protein and the conserved proline-rich domain (161)PPLP(164) regulating Vif oligomerization is crucial for its function and viral infectivity. Here, we expressed and purified wild-type Vif and a mutant protein in which alanines were substituted for the proline residues of the (161)PPLP(164) domain. Using dynamic light scattering, circular dichroism and fluorescence spectroscopy, we established the impact of these mutations on Vif oligomerization, secondary structure content and nucleic acids binding properties. In vitro, wild-type Vif formed oligomers of five to nine proteins, while Vif AALA formed dimers and/or trimers. Up to 40% of the unbound wild-type Vif protein appeared to be unfolded, but binding to the HIV-1 TAR apical loop promoted formation of β-sheets. Interestingly, alanine substitutions did not significantly affect the secondary structure of Vif, but they diminished its binding affinity and specificity for nucleic acids. Dynamic light scattering showed that Vif oligomerization, and interaction with folding-promoting nucleic acids, favor formation of high molecular mass complexes. These properties could be important for Vif functions involving RNAs. PMID:21076154

  16. Characterization of a multimeric polypeptide complex on the surface of thymus-derived cells in the Mexican axolotl.

    Science.gov (United States)

    Kerfourn, F; Guillet, F; Charlemagne, J; Tournefier, A

    1993-10-01

    We previously raised a rabbit antiserum (L12) against a 38 kD polypeptide which is expressed on the surface of thymocytes and peripheral T cells of an Urodele Amphibian, the Mexican axolotl (Ambystoma mexicanum). Here we show that L12 antibodies immunoprecipitate several labelled molecules from surface iodinated axolotl spleen cells, including the 38 kD molecule, but also two polypeptides of 43 and 22 kD which are covalently linked to other elements. Another rabbit antiserum (L10) was raised against detergent-solubilized axolotl thymocyte membranes and shown to recognize the majority of thymocytes and about half of the splenocytes in immunofluorescence. In Western blotting, L10 antibodies recognized a limited number of surface polypeptides in thymocyte and splenocyte lysates, including 43, 38, and 22 kD elements. Immune complexes formed between L10 antibodies and solubilized splenocyte membranes were used to immunize BALB/c mice intrasplenically in the aim of raising MoAbs specific for axolotl T cells. Monoclonal antibody 87.16 was shown to stain in immunofluorescence 26.7% of thymocytes and 26.8% of spleen cells. This MoAb recognized a 43 kD polypeptide that can covalently associate on the T-cell surface with several other molecules to form a multimeric complex. PMID:8211000

  17. Essential roles of insulin, AMPK signaling and lysyl and prolyl hydroxylases in the biosynthesis and multimerization of adiponectin.

    Science.gov (United States)

    Zhang, Lin; Li, Ming-Ming; Corcoran, Marie; Zhang, Shaoping; Cooper, Garth J S

    2015-01-01

    Post-translational modifications (PTMs) of the adiponectin molecule are essential for its full bioactivity, and defects in PTMs leading to its defective production and multimerization have been linked to the mechanisms of insulin resistance, obesity, and type-2 diabetes. Here we observed that, in differentiated 3T3-L1 adipocytes, decreased insulin signaling caused by blocking of insulin receptors (InsR) with an anti-InsR blocking antibody, increased rates of adiponectin secretion, whereas concomitant elevations in insulin levels counteracted this effect. Adenosine monophosphate-activated protein kinase (AMPK) signaling regulated adiponectin production by modulating the expression of adiponectin receptors, the secretion of adiponectin, and eventually the expression of adiponectin itself. We found that lysyl hydroxylases (LHs) and prolyl hydroxylases (PHs) were expressed in white-adipose tissue of ob/ob mice, wherein LH3 levels were increased compared with controls. In differentiated 3T3-L1 adipocytes, both non-specific inhibition of LHs and PHs by dipyridyl, and specific inhibition of LHs by minoxidil and of P4H with ethyl-3,4-dihydroxybenzoate, caused significant suppression of adiponectin production, more particularly of the higher-order isoforms. Transient gene knock-down of LH3 (Plod3) caused a suppressive effect, especially on the high molecular-weight (HMW) isoforms. These data indicate that PHs and LHs are both required for physiological adiponectin production and in particular are essential for the formation/secretion of the HMW isoforms. PMID:25240468

  18. Chemoselective pre-conjugate radiohalogenation of unprotected mono- and multimeric peptides via oxime formation

    Energy Technology Data Exchange (ETDEWEB)

    Poethko, T.; Schottelius, M.; Herz, M.; Haubner, R.; Henriksen, G.; Schwaiger, M.; Wester, H.J. [Nuklearmedizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Univ. Muenchen (Germany); Thumshirn, G.; Kessler, H. [Inst. fuer Organische Chemie und Biochemie, Technische Univ. Muenchen, Garching (Germany)

    2004-07-01

    As part of our ongoing efforts in the development of new {sup 18}F-labeled peptides for clinical PET imaging, a new two-step {sup 18}F-labeling methodology based on the chemoselective oxime formation between an unprotected aminooxy-functionalized peptide and a {sup 18}F-labeled aldehyde was investigated and optimized. 4-[{sup 18}F]Fluorobenzaldehyde ([{sup 18}F]FB-CHO) was prepared by direct n.c.a. fluorination of 4-formyl-N,N,N-trimethylanilinium triflate and purified by radio-HPLC or a strong-cation-exchange/reverse phase cartridge system. The aminooxyacetic acid (Aoa) modified model peptide LEF-NH{sub 2} (Leu-Glu-Phe-NH{sub 2}) and monomeric, dimeric and tetrameric RGD-containing cyclopeptides were synthesized by solid phase peptide synthesis. Radiochemical yields of N-(4-[{sup 18}F]fluorobenzylidene)-oxime-formation ([{sup 18}F]FBOA) with the Aoa-modified unprotected peptides were investigated. Optimized reaction conditions (60 C, 0.5 mM peptide, 15 min, aqueous solution, pH 2.5) resulted in 70%-90% conjugation yields for all unprotected peptides studied. Chemoselectivity was demonstrated in competition experiments with amino acid mixtures. Biodistribution in M21 melanoma bearing mice showed improved tumor uptake and excretion behaviour in the series c(RGDfE)HEG-Dpr-[{sup 18}F]FBOA < c((RGDfE)HEG){sub 2}K-Dpr-[{sup 18}F]FBOA < ((c(RGDfE)HEG){sub 2}K){sub 2}K-Dpr-[{sup 18}F]FBOA. Two hours p.i. the fraction of intact c(RGDfE)HEG-K-Dpr-[{sup 18}F]FBOA in blood, liver, kidney and tumor was > 90%, indicating high in vivo stability of the oxime linkage. Initial PET studies with (c(RGDfE)HEG){sub 2}-K){sub 2}-K-Dpr-[{sup 18}F]FBOA showed excellent imaging of M21-melanomas in mice. In conclusion, the new two-step chemoselective {sup 18}F-labeling fulfills all requirements for large scale syntheses of peptides in clinical routine. This methodology is also adaptable to other radioisotopes (e.g. radiohalogenation in general) and will thus offer a broad field of

  19. Green syntheses, v.1

    CERN Document Server

    Tundo, Pietro

    2014-01-01

    Introduction to the Green Syntheses SeriesPietro Tundo and John AndraosApplication of Material Efficiency Metrics to Assess Reaction Greenness-Illustrative Case Studies from Organic SynthesesJohn AndraosReaction 1: Synthesis of 3-Benzyl-5-Methyleneoxazolidin-2-one from N-Benzylprop-2-yn-1-Amine and CO2Qing-Wen Song and Liang-Nian HeReaction 2: Synthesis of the 5-Membered Cyclic Carbonates from Epoxides and CO2Qing-Wen Song, Liang-Nian HePart I: Green Methods for the Epoxidation of

  20. Wisdom, Intelligence & Creativity Synthesized

    Science.gov (United States)

    Sternberg, Robert J.

    2009-01-01

    How is it that smart administrators who want to do a good job often find themselves in situations that degenerate into confrontation and, ultimately, termination? In this article, the author discusses why in terms of a model of leadership--which he refers to it as WICS, an acronym for wisdom, intelligence and creativity synthesized. He describes…

  1. Research synthese Geweld verslagen

    OpenAIRE

    Knaap, L. van der; Bogaerts, S.

    2006-01-01

    Dit is een kort overzicht van de belangrijkste bevindingen uit het onderzoeksrappport 'Geweld verslagen?' waarin verslag wordt gedaan van een synthese van 48 studies naar de effecten van preventie van geweld in het publieke en semi-publieke domein. Het volledige rapport is te vinden via het vak 'Links' aan de rechterkant. Deze uitgave is verschenen in de nieuwe reeks Fact sheet (nr. 2006-23).

  2. Multimerization of GPIHBP1 and Familial Chylomicronemia from a Serine-to-Cysteine Substitution in GPIHBP1's Ly6 Domain

    DEFF Research Database (Denmark)

    Plengpanich, Wanee; Young, Stephen G; Khovidhunkit, Weerapan;

    2014-01-01

    monomers bind LPL. In keeping with that finding, there was no binding of LPL to GPIHBP1-S107C in either cell-based or cell-free binding assays. We conclude that an extra cysteine in GPIHBP1's Ly6 motif results in multimerization of GPIHBP1, defective LPL binding, and severe hypertriglyceridemia....... surface was in the form of disulfide-linked dimers and multimers, while wild-type GPIHBP1 was predominantly monomeric. An insect cell GPIHBP1 expression system confirmed the propensity of GPIHBP1-S107C to form disulfide-linked dimers and to form multimers. Functional studies showed that only GPIHBP1...

  3. Programmable electronic synthesized capacitance

    Science.gov (United States)

    Kleinberg, Leonard L. (Inventor)

    1987-01-01

    A predetermined and variable synthesized capacitance which may be incorporated into the resonant portion of an electronic oscillator for the purpose of tuning the oscillator comprises a programmable operational amplifier circuit. The operational amplifier circuit has its output connected to its inverting input, in a follower configuration, by a network which is low impedance at the operational frequency of the circuit. The output of the operational amplifier is also connected to the noninverting input by a capacitor. The noninverting input appears as a synthesized capacitance which may be varied with a variation in gain-bandwidth product of the operational amplifier circuit. The gain-bandwidth product may, in turn, be varied with a variation in input set current with a digital to analog converter whose output is varied with a command word. The output impedance of the circuit may also be varied by the output set current. This circuit may provide very small ranges in oscillator frequency with relatively large control voltages unaffected by noise.

  4. SYNTH. A spectrum synthesizer

    International Nuclear Information System (INIS)

    A computer code has been written at the Pacific Northwest Laboratory (PNL) to synthesize the results of typical gamma-ray spectroscopy experiments. The code, dubbed SYNTH, allows users to specify physical characteristics of a gamma-ray source the quantity of the nuclides producing the radiation, the source-to-detector distance, the type and thickness of absorbers, the size and composition of the detector (Ge or Nal), and the electronic set up used to gather the data. In the process of specifying the parameters needed to synthesize a spectrum, several interesting intermediate results are produced, including a photopeak transmission function vs. energy, a detector efficiency curve, and a weighted list of gamma and x rays produced from a set of nuclides. All of these intermediate results are available for graphical inspection and for printing. SYNTH runs on personal computers, is menu driven and can be customized to user specifications. SYNTH contains robust support for coaxial germanium detectors and some support for sodium iodide detectors. SYNTH is not a finished product. A number of additional developments are planned. However, the existing code has been carefully compared to spectra obtained from National Institute for Standards and Technology (NIST) certified standards with very favorable results. (author) 5 refs.; 8 figs

  5. SYNTH: A spectrum synthesizer

    International Nuclear Information System (INIS)

    A computer code has been written at the Pacific Northwest Laboratory (PNL) to synthesize the results of typical gamma ray spectroscopy experiments. The code, dubbed SYNTH, allows a user to specify physical characteristics of a gamma ray source, the quantity of the nuclides producing the radiation, the source-to-detector distance and the presence of absorbers, the type and size of the detector, and the electronic set up used to gather the data. In the process of specifying the parameters needed to synthesize a spectrum, several interesting intermediate results are produced, including a photopeak transmission function versus energy, a detector efficiency curve, and a weighted list of gamma and x rays produced from a set of nuclides. All of these intermediate results are available for graphical inspection and for printing. SYNTH runs on personal computers. It is menu driven and can be customized to user specifications. SYNTH contains robust support for coaxial germanium detectors and some support for sodium iodide detectors. SYNTH is not a finished product. A number of additional developments are planned. However, the existing code has been compared carefully to spectra obtained from National Institute for Standards and Technology (NIST) certified standards with very favorable results. Examples of the use of SYNTH and several spectral results are presented

  6. SYNTH: A spectrum synthesizer

    International Nuclear Information System (INIS)

    A computer code has been written at the Pacific Northwest Laboratory (PNL) to synthesize the results of typical gamma-ray spectroscopy experiments. The code, dubbed SYNTH, allows a use r to specify physical characteristics of a gamma-ray source, the quantity of the nuclides producing the radiation, the source-to-detector distance and the type and thickness of absorbers, the size and composition of the detector (Ge or NaI), and the electronic set up used to gather the data. In the process of specifying the parameters needed to synthesize a spectrum, several interesting intermediate results are produced, including a photopeak transmission function vs energy, a detector efficiency curve, and a weighted list of gamma and x rays produced from a set of nuclides. All of these intermediate results are available for graphical inspection and for printing. SYNTH runs on personal computers. It is menu driven and can be customized to user specifications. SYNTH contains robust support for coaxial germanium detectors and some support for sodium iodide detectors. SYNTH is not a finished product. A number of additional developments are planned. However, the existing code has been compared carefully to spectra obtained from National Institute for Standards and Technology (NIST) certified standards with very favorable results. Examples of the use of SYNTH and several spectral results will be presented

  7. Monomeric, dimeric and multimeric system of RGD peptides radiolabeled with {sup 177}Lu for tumors therapy that expressing αβ integrin s; Sistema monomerico, dimerico y multimerico de peptidos de RGD radiomarcados con {sup 177}Lu para terapia de tumores que expresan integrinas αβ

    Energy Technology Data Exchange (ETDEWEB)

    Luna G, M. A.

    2014-07-01

    The conjugation of peptides to gold nanoparticles (AuNPs) produces biocompatible and stable multimeric systems with target-specific molecular recognition. Peptides based on the cyclic Arg-Gly-Asp (RGD) sequence have been reported as high affinity agents for the α(v)β(3) and α(v)β(5) integrin. The aim of this research was to prepare a multimeric system of {sup 177}Lu-labeled gold nanoparticles conjugated to c[RGDfK(C)] [cyclo(Arg-Gly-Asp-Phe-Lys(Cys)] peptides and to compare the radiation absorbed dose with that of {sup 177}Lu-labeled monomeric and dimeric RGD peptides to α(v)β(3) integrin-positive U87MG tumors in mice, as well as, evaluate the in vitro potential {sup 177}Lu-AuNP-c[RGDfK(C)] as a plasmonic photothermal therapy and targeted radiotherapy system in MCF7 breast cancer cells. DOTA-GGC (1,4,7,10-tetraaza cyclododecane-N,N,N-tetraacetic-Gly-Gly-Cys) and c[RGDfK(C)] peptides were synthesized and conjugated to AuNPs by the spontaneous reaction of the thiol groups. Tem, UV-Vis, XP S, Raman and Far-IR spectroscopy techniques demonstrated that AuNPs were functionalized with the peptides. To obtain {sup 177}Lu-AuNP-c[RGDfK(C)], the {sup 177}Lu-DOTA-GGC radio peptide was first prepared and added to a solution of AuNPs followed by c[RGDfK(C)] (25 μL, 5 μM) at 18 grades C for 15 min. {sup 177}Lu-DOTA-GGC, {sup 177}Lu- DOTA-cRGDfK and {sup 177}Lu-DOTA-E-c(RGDfK){sub 2} were prepared by adding {sup 177}LuCl{sub 3} (370 MBq) to 5 μL (1 mg/ml) of the DOTA derivative diluted with 50 μL of 1 M acetate buffer at ph 5. The mixture was incubated at 90 grades C in a block heater for 30 min. Radiochemical purity was determined by ultrafiltration and HPLC analyses. After laser irradiation, the presence of c[RGDfK(C)]-AuNP in cells caused a significant increase in the temperature of the medium (50.5 grades C, compared to 40.3 grades C without AuNPs) resulting in a significant decrease in MCF7 cell viability down to 9 %. After treatment with {sup 177}Lu

  8. Association between multimeric adiponectin and free leptin index with atherogenic dyslipidemia in non-diabetic obese men

    Directory of Open Access Journals (Sweden)

    Candra Ninghayu

    2011-05-01

    Full Text Available Background: To analyze the role of various adiponectin and free leptin index on the occurrence of atherogenic dislipidemia in non-diabetic central obese men.Methods: This is a cross-sectional study on 120 non-diabetic central obese men that was done in Jakarta. The measured indicators were total adiponectin, high molecular weight adiponectin (HMW adiponectin, medium molecular weight adiponectin (MMW adiponectin, low molecular weight adiponectin (LMW adiponectin, leptin, soluble leptin receptor, triglycerides, high-density lipoprotein cholesterol (HDL cholesterol, low density lipoprotein cholesterol (LDL cholesterol and apolipoprotein B (Apo B. Atherogenic dyslipidemia was characterized by reduced level of HDL cholesterol, and high levels of triglyceride and small dense LDL (sdLDL. Ratio of LDL cholesterol and Apo B were calculated to get sdLDL. Free Leptin Index (FLI was the ratio between total leptin and soluble leptin receptor (sOB-R, and median values were used as cut off to defi ne high and low values of each parameter. Cross tabulation were done on categorical data. Relationships between multimeric adiponectin and free leptin index with atherogenic lipids were analyzed by using Spearman analysis. Further, the interaction of all indicators with the occurence of atherogenic dyslipidemia was analyzed using binary logistic regression.Results: A negative correlation of HMW adiponectin with atherogenic dyslipidemia (p < 0.05, whereas there were no correlation between MMW adiponectin and LMW adiponectin with atherogenic dyslipidemia (p > 0.05. Free Leptin Index was associated positively with atherogenic dyslipidemia (p < 0.05. Odds Ratio (OR of HMW adiponectin for the occurrence of atherogenic dyslipidemia was 3.62 (p < 0.05, where as OR of FLI with atherogenic dyslipidemia was 4.57 (p < 0.05.Conclusion: HMW Adiponectin and FLI might contribute to atherogenic dyslipidemia in central obese non-diabetic males. (Med J Indones 2011; 20

  9. Solvent resistant microfluidic DNA synthesizer.

    Science.gov (United States)

    Huang, Yanyi; Castrataro, Piero; Lee, Cheng-Chung; Quake, Stephen R

    2007-01-01

    We fabricated a microfluidic DNA synthesizer out of perfluoropolyether (PFPE), an elastomer with excellent chemical compatibility which makes it possible to perform organic chemical reactions, and synthesized 20-mer oligonucleotides on chip. PMID:17180201

  10. TRIM5α and TRIMCyp form apparent hexamers and their multimeric state is not affected by exposure to restriction-sensitive viruses or by treatment with pharmacological inhibitors

    Directory of Open Access Journals (Sweden)

    Berthoux Lionel

    2009-11-01

    Full Text Available Abstract Proteins of the TRIM5 family, such as TRIM5α and the related TRIMCyp, are cytoplasmic factors that can inhibit incoming retroviruses. This type of restriction requires a direct interaction between TRIM5 proteins and capsid proteins that are part of mature, intact retroviral cores. In such cores, capsids are arranged as hexameric units. Multiple lines of evidence imply that TRIM5 proteins themselves interact with retroviral cores as multimers. Accordingly, stabilization by crosslinking agents has revealed that TRIM5α and TRIMCyp are present as trimers in mammalian cells. We report here that TRIM5 proteins seem to form dimers, trimers, hexamers and multimers of higher complexity in mammalian cells. The hexameric form in particular seems to be the most abundant multimer. Multimerization did not involve disulfide bridges and was not affected by infection with restriction-sensitive viruses or by treatment with the known TRIM5 inhibitors arsenic trioxide, MG132 and cyclosporine A. We conclude that TRIM5 multimerization results from more than one protein-protein interface and that it is seemingly not triggered by contact with retroviral cores.

  11. The Benzyl Ester Group of Amino Acid Monomers Enhances Substrate Affinity and Broadens the Substrate Specificity of the Enzyme Catalyst in Chemoenzymatic Copolymerization.

    Science.gov (United States)

    Ageitos, Jose Manuel; Yazawa, Kenjiro; Tateishi, Ayaka; Tsuchiya, Kousuke; Numata, Keiji

    2016-01-11

    The chemoenzymatic polymerization of amino acid monomers by proteases involves a two-step reaction: the formation of a covalent acyl-intermediate complex between the protease and the carboxyl ester group of the monomer and the subsequent deacylation of the complex by aminolysis to form a peptide bond. Although the initiation with the ester group of the monomer is an important step, the influence of the ester group on the polymerization has not been studied in detail. Herein, we studied the effect of the ester groups (methyl, ethyl, benzyl, and tert-butyl esters) of alanine and glycine on the synthesis of peptides using papain as the catalyst. Alanine and glycine were selected as monomers because of their substantially different affinities toward papain. The efficiency of the polymerization of alanine and glycine benzyl esters was much greater than that of the other esters. The benzyl ester group therefore allowed papain to equally polymerize alanine and glycine, even though the affinity of alanine toward papain is substantially higher. The characterization of the copolymers of alanine and glycine in terms of the secondary structure and thermal properties revealed that the thermal stability of the peptides depends on the amino acid composition and resultant secondary structure. The current results indicate that the nature of the ester group drastically affects the polymerization efficiency and broadens the substrate specificity of the protease. PMID:26620763

  12. Doclet To Synthesize UML

    Science.gov (United States)

    Barry, Matthew R.; Osborne, Richard N.

    2005-01-01

    The RoseDoclet computer program extends the capability of Java doclet software to automatically synthesize Unified Modeling Language (UML) content from Java language source code. [Doclets are Java-language programs that use the doclet application programming interface (API) to specify the content and format of the output of Javadoc. Javadoc is a program, originally designed to generate API documentation from Java source code, now also useful as an extensible engine for processing Java source code.] RoseDoclet takes advantage of Javadoc comments and tags already in the source code to produce a UML model of that code. RoseDoclet applies the doclet API to create a doclet passed to Javadoc. The Javadoc engine applies the doclet to the source code, emitting the output format specified by the doclet. RoseDoclet emits a Rose model file and populates it with fully documented packages, classes, methods, variables, and class diagrams identified in the source code. The way in which UML models are generated can be controlled by use of new Javadoc comment tags that RoseDoclet provides. The advantage of using RoseDoclet is that Javadoc documentation becomes leveraged for two purposes: documenting the as-built API and keeping the design documentation up to date.

  13. Synthesizing Exoplanet Demographics

    Science.gov (United States)

    Clanton, Christian

    2016-01-01

    The discovery of thousands of exoplanets has revealed a large diversity of systems, the majority of which look nothing like our own. On the theoretical side, we are able to make ab initio calculations that make predictions about the properties of exoplanets. However, in order to link these predictions with observations, we must construct a statistical census of exoplanet demographics over as broad a range of parameters as possible. Current constraints on exoplanet demographics are typically constructed using the results of individual surveys using a single detection technique, and thus are incomplete. The only way to derive a statistically-complete census that samples a wide region of exoplanet parameter space is to synthesize the results from surveys employing all of the different discovery methods at our disposal. I present the first studies to demonstrate that this is actually possible, and describe a (mostly) de-biased exoplanet census that is constructed from the synthesis of results from microlensing, radial velocity, and direct imaging surveys. I will also discuss future work that will include the results of transit surveys (in particular, Kepler discoveries) to complete the census of exoplanets in our Galaxy, and describe the application of this census to develop the most comprehensive, observationally-constrained models of planet formation and evolution that have been derived to date.

  14. Complete chemoenzymatic synthesis of the Forssman antigen using novel glycosyltransferases identified in Campylobacter jejuni and Pasteurella multocida

    Science.gov (United States)

    We have identified an alpha1,4-galactosyltransferase (CgtD) and a beta1,3-N-acetylgalactosaminyltransferase (CgtE) in the lipooligosaccharide (LOS) locus of Campylobacter jejuni LIO87. Strains that carry these genes may have the capability of synthesizing mimics of the P blood group antigens of the ...

  15. GM3, GM2 and GM1 mimics designed for biosensing: chemoenzymatic synthesis, target affinities and 900 MHz NMR analysis

    NARCIS (Netherlands)

    Pukin, A.V.; Weijers, C.A.G.M.; Lagen, van B.; Wechselberger, R.; Sun, B.; Gilbert, M.; Karwaski, M.F.; Florack, D.E.A.; Jacobs, B.C.; Tio-Gillen, A.P.; Belkum, van A.; Endtz, H.P.; Visser, G.M.; Zuilhof, H.

    2008-01-01

    Undec-10-enyl, undec-10-ynyl and 11-azidoundecyl glycoside analogues corresponding to the oligosaccharides of human gangliosides GM3, GM2 and GM1 were synthesized in high yields using glycosyltransferases from Campylobacter jejuni. Due to poor water solubility of the substrates, the reactions were c

  16. Chemo-enzymatic synthesis of poly-N-acetyllactosamine (poly-LacNAc) structures and their characterization for CGL2-galectin-mediated binding of ECM glycoproteins to biomaterial surfaces

    Czech Academy of Sciences Publication Activity Database

    Sauerzapfe, B.; Křenek, Karel; Schmiedel, J.; Wakarchuk, W.W.; Pelantová, Helena; Křen, Vladimír; Elling, L.

    2009-01-01

    Roč. 26, č. 2 (2009), s. 141-159. ISSN 0282-0080 R&D Projects: GA AV ČR IAA400200503; GA MŠk(CZ) LC06010 Grant ostatní: CZ(CZ) DAAD-AV ČR projekt PPP-D7-CZ 26/04-05D/03/44448 Institutional research plan: CEZ:AV0Z50200510 Keywords : chemo-enzymatic sysnthesis * galectin binding * biomaterials Subject RIV: EE - Microbiology, Virology Impact factor: 2.500, year: 2009

  17. Chemoenzymatic Synthesis of Amphiphilic Core-Shell TMP-(PCL-b-PGMA2)3 Star-Block Copolymer.

    Science.gov (United States)

    Wang, Shuwei; Li, Yapeng; Zhang, Xiaonan; Chen, Xuesi; Wang, Jingyuan; Zhang, He-Xin; Yoon, Keun-Byoung

    2015-06-01

    A novel well-defined amphiphilic Core-Shell star-block copolymer was synthesized from trimethylolpropane, ε-caprolactone, and glycidyl methacrylate by a combination of enzymatic ring-opening polymerization and atom transfer radical polymerization. The structure and molecular weight of the macroinitiator and the star-block copolymer were confirmed by means of nuclear magnetic resonance and gel permeation chromatography. The effects of the glycidyl methacrylate sequence length on the hydrodynamic diameter and morphology of the polymer micelles were investigated by dynamic light scattering and transmission electron microscopy, respectively. PMID:26369103

  18. Fully automated parallel oligonucleotide synthesizer

    Czech Academy of Sciences Publication Activity Database

    Lebl, M.; Burger, Ch.; Ellman, B.; Heiner, D.; Ibrahim, G.; Jones, A.; Nibbe, M.; Thompson, J.; Mudra, Petr; Pokorný, Vít; Poncar, Pavel; Ženíšek, Karel

    2001-01-01

    Roč. 66, č. 8 (2001), s. 1299-1314. ISSN 0010-0765 Institutional research plan: CEZ:AV0Z4055905 Keywords : automated oligonucleotide synthesizer Subject RIV: CC - Organic Chemistry Impact factor: 0.778, year: 2001

  19. RAMESES publication standards: realist syntheses

    Directory of Open Access Journals (Sweden)

    Wong Geoff

    2013-01-01

    Full Text Available Abstract Background There is growing interest in realist synthesis as an alternative systematic review method. This approach offers the potential to expand the knowledge base in policy-relevant areas - for example, by explaining the success, failure or mixed fortunes of complex interventions. No previous publication standards exist for reporting realist syntheses. This standard was developed as part of the RAMESES (Realist And MEta-narrative Evidence Syntheses: Evolving Standards project. The project's aim is to produce preliminary publication standards for realist systematic reviews. Methods We (a collated and summarized existing literature on the principles of good practice in realist syntheses; (b considered the extent to which these principles had been followed by published syntheses, thereby identifying how rigor may be lost and how existing methods could be improved; (c used a three-round online Delphi method with an interdisciplinary panel of national and international experts in evidence synthesis, realist research, policy and/or publishing to produce and iteratively refine a draft set of methodological steps and publication standards; (d provided real-time support to ongoing realist syntheses and the open-access RAMESES online discussion list so as to capture problems and questions as they arose; and (e synthesized expert input, evidence syntheses and real-time problem analysis into a definitive set of standards. Results We identified 35 published realist syntheses, provided real-time support to 9 on-going syntheses and captured questions raised in the RAMESES discussion list. Through analysis and discussion within the project team, we summarized the published literature and common questions and challenges into briefing materials for the Delphi panel, comprising 37 members. Within three rounds this panel had reached consensus on 19 key publication standards, with an overall response rate of 91%. Conclusion This project used multiple

  20. Intracellular interactions between APOBEC3G, RNA, and HIV-1 Gag: APOBEC3G multimerization is dependent on its association with RNA

    Directory of Open Access Journals (Sweden)

    Friew Yeshitila N

    2009-06-01

    Full Text Available Abstract Background Host restriction factor APOBEC3G (A3G blocks human immunodeficiency virus type 1 (HIV-1 replication by G-to-A hypermutation, and by inhibiting DNA synthesis and provirus formation. Previous reports have suggested that A3G is a dimer and its virion incorporation is mediated through interactions with viral or nonviral RNAs and/or HIV-1 Gag. We have now employed a bimolecular fluorescence complementation assay (BiFC to analyze the intracellular A3G-A3G, A3G-RNA, and A3G-Gag interactions in living cells by reconstitution of yellow fluorescent protein (YFP from its N- or C-terminal fragments. Results The results obtained with catalytic domain 1 and 2 (CD1 and CD2 mutants indicate that A3G-A3G and A3G-Gag multimerization is dependent on an intact CD1 domain, which is required for RNA binding. A mutant HIV-1 Gag that exhibits reduced RNA binding also failed to reconstitute BiFC with wild-type A3G, indicating a requirement for both HIV-1 Gag and A3G to bind to RNA for their multimerization. Addition of a non-specific RNA binding peptide (P22 to the N-terminus of a CD1 mutant of A3G restored BiFC and virion incorporation, but failed to inhibit viral replication, indicating that the mutations in CD1 resulted in additional defects that interfere with A3G's antiviral activity. Conclusion These studies establish a robust BiFC assay for analysis of intracellular interactions of A3G with other macromolecules. The results indicate that in vivo A3G is a monomer that forms multimers upon binding to RNA. In addition, we observed weak interactions between wild-type A3G molecules and RNA binding-defective mutants of A3G, which could explain previously described protein-protein interactions between purified A3G molecules.

  1. Synthese und Eigenschaften von Kohlenstoffnitriden

    OpenAIRE

    Horvath-Bordon, Elisabeta

    2004-01-01

    In der hier vorliegenden Arbeit über die „Synthese und Eigenschaften von Kohlenstoffnitriden“ wird im ersten Teil über die Synthese, die Strukturaufklärung, thermische Stabilität und die optischen Eigenschaften von Tri-s-triazin Derivaten (Cyamelurate, Melonate, Melem usw.) berichtet. Weil sich molekulare und polymere Tri-s-triazin Derivaten relativ einfach in reiner Form darstellen lassen, wurden sie als Precursoren zur Herstellung von harten Kohlenstoffnitriden ausgewählt. Im zweiten Teil w...

  2. Method of synthesizing pyrite nanocrystals

    Science.gov (United States)

    Wadia, Cyrus; Wu, Yue

    2013-04-23

    A method of synthesizing pyrite nanocrystals is disclosed which in one embodiment includes forming a solution of iron (III) diethyl dithiophosphate and tetra-alkyl-ammonium halide in water. The solution is heated under pressure. Pyrite nanocrystal particles are then recovered from the solution.

  3. Template-synthesized opal hydrogels

    Institute of Scientific and Technical Information of China (English)

    LI Jun; JI Lijun; RONG Jianhua; YANG Zhenzhong

    2003-01-01

    Opal hydrogels could be synthesized with polymer inverse opal template. A pH responsive opal N-iso- propylacrylamide/acrylic acid copolymerized hydrogel was prepared as an example. The ordered structure and response to pH were investigated. Through the sol-gel process of tetrabutyl titanate, opal titania was obtained with the opal hydrogel template.

  4. X-Band PLL Synthesizer

    Directory of Open Access Journals (Sweden)

    P. Kutin

    2006-04-01

    Full Text Available This paper deals with design and realization of a PLL synthesizer for the microwave X−band. The synthesizer is intended for use as a local oscillator in a K−band downconverter. The design goal was to achieve very low phase noise and spurious free signal with a sufficient power level. For that purpose a low phase noise MMIC VCO was used in phase locked loop. The PLL works at half the output frequency, therefore there is a frequency doubler at the output of the PLL. The output signal from the frequency doubler is filtered by a band-pass filter and finally amplified by a single stage amplifier.

  5. Catalytic method for synthesizing hydrocarbons

    Science.gov (United States)

    Sapienza, Richard S.; Sansone, Michael J.; Slegeir, William A. R.

    1984-01-01

    A method for synthesizing hydrocarbons from carbon monoxide and hydrogen by contacting said gases with a slurry of a catalyst composed of palladium or platinum and cobalt supported on a solid phase is disclosed. The catalyst is prepared by heating a heterogeneous component of the palladium or platinum deposited on the solid support in a solution of cobalt carbonyl or precursors thereof. The catalyst exhibits excellent activity, stability in air, and produces highly desirable product fractions even with dilute gaseous reactants.

  6. Chemoenzymatic synthesis of a series of 4-substituted glutamate analogues and pharmacological characterization at human glutamate transporters subtypes 1-3

    DEFF Research Database (Denmark)

    Alaux, Sebastien; Kusk, Mie; Sagot, Emanuelle;

    2005-01-01

    A series of nine L-2,4-syn-4-alkylglutamic acid analogues (1a-i) were synthesized in high yield and high enantiomeric excess (>99% ee) from their corresponding 4-substituted ketoglutaric acids (2a-i), using the enzyme aspartate aminotransferase (AAT) from pig heart or E. coli. The synthesized...

  7. YgfX (CptA) is a multimeric membrane protein that interacts with the succinate dehydrogenase assembly factor SdhE (YgfY).

    Science.gov (United States)

    McNeil, Matthew B; Iglesias-Cans, Marina C; Clulow, James S; Fineran, Peter C

    2013-07-01

    Serratia sp. strain ATCC 39006 produces the red-pigmented antibiotic prodigiosin. Prodigiosin biosynthesis is regulated by a complex hierarchy that includes the uncharacterized protein YgfX (DUF1434). The ygfX gene is co-transcribed with sdhE, an FAD assembly factor essential for the flavinylation and activation of the SdhA subunit of succinate dehydrogenase (SDH), a central enzyme in the tricarboxylic acid cycle and electron transport chain. The sdhEygfX operon is highly conserved within the Enterobacteriaceae, suggesting that SdhE and YgfX function together. We performed an extensive mutagenesis to gain molecular insights into the uncharacterized protein YgfX, and have investigated the relationship between YgfX and SdhE. YgfX localized to the membrane, interacted with itself, forming dimers or larger multimers, and interacted with SdhE. The transmembrane helices of YgfX were critical for protein function and the formation of YgfX multimers. Site-directed mutagenesis of residues conserved in DUF1434 proteins revealed a periplasmic tryptophan and a cytoplasmic aspartate that were crucial for YgfX activity. Both of these amino acids were required for the formation of YgfX multimers and interactions with SdhE but not membrane localization. Multiple cell division proteins were identified as putative interaction partners of YgfX and overexpression of YgfX had effects on cell morphology. These findings represent an important step in understanding the function of DUF1434 proteins. In contrast to a recent report, we found no evidence that YgfX and SdhE form a toxin-antitoxin system. In summary, YgfX functions as a multimeric membrane-bound protein that interacts with SdhE, an important FAD assembly factor that controls SDH activity. PMID:23657679

  8. Synthesized Optimization of Triangular Mesh

    Institute of Scientific and Technical Information of China (English)

    HU Wenqiang; YANG Wenyu

    2006-01-01

    Triangular mesh is often used to describe geometric object as computed model in digital manufacture, thus the mesh model with both uniform triangular shape and excellent geometric shape is expected. But in fact, the optimization of triangular shape often is contrary with that of geometric shape. In this paper, one synthesized optimizing algorithm is presented through subdividing triangles to achieve the trade-off solution between the geometric and triangular shape optimization of mesh model. The result mesh with uniform triangular shape and excellent topology are obtained.

  9. Method of synthesizing tungsten nanoparticles

    Science.gov (United States)

    Thoma, Steven G; Anderson, Travis M

    2013-02-12

    A method to synthesize tungsten nanoparticles has been developed that enables synthesis of nanometer-scale, monodisperse particles that can be stabilized only by tetrahydrofuran. The method can be used at room temperature, is scalable, and the product concentrated by standard means. Since no additives or stabilizing surfactants are required, this method is particularly well suited for producing tungsten nanoparticles for dispersion in polymers. If complete dispersion is achieved due to the size of the nanoparticles, then the optical properties of the polymer can be largely maintained.

  10. Inhibition of angiogenesis, tumour growth and experimental metastasis of human fibrosarcoma cells HT1080 by a multimeric form of the laminin sequence Tyr-Ile-Gly-Ser-Arg (YIGSR).

    OpenAIRE

    Iwamoto, Y; Nomizu, M; Yamada, Y.; Ito, Y.; K.Tanaka; Sugioka, Y.

    1996-01-01

    A multimeric peptide, Ac-Y16, consisting of 16 YIGSR sequences from laminin was evaluated for its effect on experimental metastasis, angiogenesis and tumour growth of HT1080 human fibrosarcoma cells. Co-injection of 0.5 mg per mouse of Ac-Y16 i.v. with HT 1080 cells inhibited lung colonisation by 100%, whereas 0.5 mg per mouse of monomeric Ac-YIGSR-NH2(AcY1) inhibited by 94%. Ac-Y16 did not show any direct cytotoxicity in tumour cells in vivo. The effect of the peptides on angiogenesis and tu...

  11. Disulfide Bond-mediated Multimerization of Ask1 and Its Reduction by Thioredoxin-1 Regulate H2O2-induced c-Jun NH2-terminal Kinase Activation and Apoptosis

    OpenAIRE

    Nadeau, Philippe J.; Charette, Steve J; Toledano, Michel B.; Landry, Jacques

    2007-01-01

    Apoptosis signal-regulated kinase-1 (Ask1) lies upstream of a major redox-sensitive pathway leading to the activation of Jun NH2-terminal kinase (JNK) and the induction of apoptosis. We found that cell exposure to H2O2 caused the rapid oxidation of Ask1, leading to its multimerization through the formation of interchain disulfide bonds. Oxidized Ask1 was fully reduced within minutes after induction by H2O2. During this reduction, the thiol-disulfide oxidoreductase thioredoxin-1 (Trx1) became ...

  12. Synthese de champs sonores adaptative

    Science.gov (United States)

    Gauthier, Philippe-Aubert

    La reproduction de champs acoustiques est une approche physique au probleme technologique de la spatialisation sonore. Cette these concerne l'aspect physique de la reproduction de champs acoustiques. L'objectif principal est l'amelioration de la reproduction de champs acoustiques par "synthese de champs acoustiques" ("Wave Field Synthesis", WFS), une approche connue, basee sur des hypotheses de champ libre, a l'aide du controle actif par l'ajout de capteurs de l'erreur de reproduction et d'une boucle fermee. Un premier chapitre technique (chapitre 4) expose les resultats d'appreciation objective de la WFS par simulations et mesures experimentales. L'effet indesirable de la salle de reproduction sur les qualites objectives de la WFS fut illustre. Une premiere question de recherche fut ensuite abordee (chapitre 5), a savoir s'il est possible de reproduire des champs progressifs en salle dans un paradigme physique de controle actif: cette possibilite fut prouvee. L'approche technique privilegiee, "synthese de champs adaptative" ("Adaptive Wave Field Synthesis" [AWFS]), fut definie, puis simulee (chapitre 6). Cette approche d'AWFS comporte une originalite en controle actif et en reproduction de champs acoustiques: la fonction cout quadratique representant la minimisation des erreurs de reproduction inclut une regularisation de Tikhonov avec solution a priori qui vient de la WFS. L'etude de l'AWFS a l'aide de la decomposition en valeurs singulieres (chapitre 7) a permis de comprendre les mecanismes propres a l'AWFS. C'est la deuxieme principale originalite de la these. L'algorithme FXLMS (LMS et reference filtree) est modifie pour l'AWFS (chapitre 8). Le decouplage du systeme par decomposition en valeurs singulieres est illustre dans le domaine du traitement de signal et l'AWFS basee sur le controle independant des modes de rayonnement est simulee (chapitre 8). Ce qui constitue la troisieme originalite principale de cette these. Ces simulations du traitement de signal

  13. FUNCTIONAL POLYHYDROXYALKANOATES SYNTHESIZED BY MICROORGANISMS

    Institute of Scientific and Technical Information of China (English)

    Guo-qiang Chen; Qiong Wu; Kai Zhao; Peter H.Yu

    2000-01-01

    Many bacteria have been found to synthesize a family of polyesters termed polyhydroxyalkanoate, abbreviated as PHA. Some interesting physical properties of PHAs such as piezoelectricity, non-linear optical activity, biocompatibility and biodegradability offer promising applications in areas such as degradable packaging, tissue engineering and drug delivery.Over 90 PHAs with various structure variations have been reported and the number is still increasing. The mechanical property of PHAs changes from brittle to flexible to elastic, depending on the side-chainlength of PHA. Many attempts have been made to produce PHAs as biodegradable plastics using various microorganisms obtained from screening natural environments, genetic engineering and mutation. Due to the high production cost, PHAs still can not compete with the nondegradable plastics, such as polyethylene and polypropylene. Various processes have been developed using low cost raw materials for fermentation and an inorganic extraction process for PHA purification. However, a super PHA production strain may play the most critical role for any large-scale PHA production. Our recent study showed that PHA synthesis is a common phenomenon among bacteria inhabiting various locations, especially oil-contaminated soils. This is very important for finding a suitable bacterial strain for PHA production. In fact, PHA production strains capable of rapid growth and rapid PHA synthesis on cheap molasses substrate have been found on molasses contaminated soils. A combination of novel properties and lower cost will allow easier commercialization of PHA for many applications.

  14. Composites comprising biologically-synthesized nanomaterials

    Science.gov (United States)

    Curran, Seamus; Dias, Sampath; Blau, Werner; Wang, Jun; Oremland, Ronald S; Baesman, Shaun

    2013-04-30

    The present disclosure describes composite materials containing a polymer material and a nanoscale material dispersed in the polymer material. The nanoscale materials may be biologically synthesized, such as tellurium nanorods synthesized by Bacillus selenitireducens. Composite materials of the present disclosure may have optical limiting properties and find use in optical limiting devices.

  15. Progress in synthesizing functional nano materials

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ With the consistent investment, the research team directed by Prof. Yadong Li of Chemistry Department of Tsinghua University achieved new progress in synthesizing nano materials with specific functions. The research team led by Prof.

  16. Freestanding doped silicon nanocrystals synthesized by plasma

    International Nuclear Information System (INIS)

    Freestanding silicon nanocrystals (Si NCs) have recently gained great popularity largely due to their easily accessible surface and flexible incorporation into device structures. In the past decade plasmas have been increasingly employed to synthesize freestanding Si NCs. As freestanding Si NCs move closer to applications in a variety of fields such as electronics, thermoelectrics and lithium-ion batteries, doping becomes more imperative. Such a context explains the current great interest in plasma-synthesized doped freestanding Si NCs. In this work we review the synthesis of freestanding doped Si NCs by plasma. Doping-induced structural, electronic, optical and oxidation properties of Si NCs are discussed. We also review the applications of plasma-synthesized doped freestanding Si NCs that have been demonstrated so far. The development of freestanding doped Si NCs synthesized by plasma in the future is envisioned. (review article)

  17. Syntheses and Functional Properties of Phthalocyanines

    Directory of Open Access Journals (Sweden)

    Keiichi Sakamoto

    2009-08-01

    Full Text Available Metal phthalocyanine tetrasulfonic acids, metal phthalocyanine octacarboxylic acids, metal octakis(hexyloxymethylphthalocyanines, and metal anthraquinocyanines have been synthesized. Then, zinc bis(1,4-didecylbenzo-bis(3,4-pyridoporphyrazines, the cyclotetramerization products of a 1:1 mixture of 3,6-didecylphthalonitrile and 3,4-dicyanopyridine, were synthesized. Futher, subphthalocyanine and its derivatives, with substituents such as thiobutyl and thiophenyl moieties were synthesized. Electrochemical measurements were performed on the abovementioned phthalocyanine derivatives and analogues in order to examine their electron transfer abilities and electrochemical reaction mechanisms in an organic solvent. Moreover, 1,4,8,11,15,18,22,25-octakis(thiophenylmethyl phthalocyanes were synthesized. The Q-bands of the latter compounds appeared in the near-infrared region. Furthermore, non-colored transparent films in the visible region can be produced.

  18. Raman assisted lightwave synthesized frequency sweeper

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier; Rottwitt, Karsten

    2010-01-01

    We present a Lightwave Synthesized Frequency Sweeper comprising a Raman amplifier for loss compensation. The generated pulse train contains 123 pulses and has a flat signal level as well as a low noise level.......We present a Lightwave Synthesized Frequency Sweeper comprising a Raman amplifier for loss compensation. The generated pulse train contains 123 pulses and has a flat signal level as well as a low noise level....

  19. Enzymatic kinetic resolution and chemoenzymatic dynamic kinetic resolution of delta-hydroxy esters. An efficient route to chiral delta-lactones.

    Science.gov (United States)

    Pàmies, Oscar; Bäckvall, Jan-E

    2002-02-22

    A successful kinetic resolution of a racemic mixture of delta-hydroxy esters 1 was obtained via lipase-catalyzed transesterification (E value up to 360). The combination of the enzymatic kinetic resolution with a ruthenium-catalyzed alcohol racemization led to an efficient dynamic kinetic resolution (ee up to 99% and conversion up to 92%). The synthetic utility of this procedure was illustrated by the practical syntheses of delta-lactones (R)-6-methyl- and (R)-6-ethyl-tetrahydropyran-2-one and (S)-5-(tert-butyldimethylsiloxy)heptanal. The former are important building blocks in the synthesis of natural products and biologically active compounds, and the latter is a key intermediate in the synthesis of widely used commercial insecticide Spinosyn A. PMID:11846671

  20. Radiolytic syntheses of nanoparticles in supramolecular assemblies.

    Science.gov (United States)

    Chen, Qingde; Shen, Xinghai; Gao, Hongcheng

    2010-08-11

    Ionizing radiation is a powerful method in the syntheses of nanoparticles (NPs). The application of ionizing radiation in supramolecular assemblies can afford us more unique conditions to control the composition and morphology of the NPs. So far, most work focused on water-in-oil (W/O) microemulsions or reversed micelles. In this supramolecular organization, it has been proved that the effects of many conditions on the yield of e(aq)(-) play a key role, remarkably different from the mechanism in routine chemical method. Besides, some supramolecular assemblies of cyclodextrins and ionic liquids have been used in the syntheses of NPs by ionizing radiation, and many novel and interesting phenomena appeared. This review is intended to underline the three significant aspects of the radiolytic syntheses of NPs in supramolecular assemblies. PMID:20653087

  1. Total Syntheses of Periconiasins A-E.

    Science.gov (United States)

    Tian, Chong; Lei, Xiaoqiang; Wang, Yuanhao; Dong, Zhen; Liu, Gang; Tang, Yefeng

    2016-06-01

    The first and collective total syntheses of periconiasins A-E, a group of naturally occurring cytochalasans, were achieved by a series of rationally designed or bioinspired transformations. Salient features of the syntheses include a tandem aldol condensation/Grob fragmentation to assemble the linear polyketide-amino acid hybrid precursor, a Diels-Alder macrocylization to construct the 9/6/5 tricyclic core of periconiasins A-C, and a transannular carbonyl-ene reaction to forge the polycyclic framework of periconiasins D and E. PMID:27121397

  2. High pressure syntheses of carbonates. 8

    International Nuclear Information System (INIS)

    The ternary carbonates TlLn(CO3)2 with Ln = La to Lu and Y are synthesized at 3500C by dehydration of the carbonates TlLn(CO3)2xxH2O or at 5000C by reaction of Tl2CO3 and Ln2(C2O4)3xyH2O under 3000 bar CO2. X-ray and IR investigations show the existence of five different structures. The compound Tl5La(CO3)4 is synthesized and X-ray and IR investigations were performed. (author)

  3. Glycoengineered Monoclonal Antibodies with Homogeneous Glycan (M3, G0, G2, and A2 Using a Chemoenzymatic Approach Have Different Affinities for FcγRIIIa and Variable Antibody-Dependent Cellular Cytotoxicity Activities.

    Directory of Open Access Journals (Sweden)

    Masaki Kurogochi

    Full Text Available Many therapeutic antibodies have been developed, and IgG antibodies have been extensively generated in various cell expression systems. IgG antibodies contain N-glycans at the constant region of the heavy chain (Fc domain, and their N-glycosylation patterns differ during various processes or among cell expression systems. The Fc N-glycan can modulate the effector functions of IgG antibodies, such as antibody-dependent cellular cytotoxicity (ADCC and complement dependent cytotoxicity (CDC. To control Fc N-glycans, we performed a rearrangement of Fc N-glycans from a heterogeneous N-glycosylation pattern to homogeneous N-glycans using chemoenzymatic approaches with two types of endo-β-N-acetyl glucosaminidases (ENG'ases, one that works as a hydrolase to cleave all heterogeneous N-glycans, another that is used as a glycosynthase to generate homogeneous N-glycans. As starting materials, we used an anti-Her2 antibody produced in transgenic silkworm cocoon, which consists of non-fucosylated pauci-mannose type (Man2-3GlcNAc2, high-mannose type (Man4-9GlcNAc2, and complex type (Man3GlcNAc3-4 N-glycans. As a result of the cleavage of several ENG'ases (endoS, endoM, endoD, endoH, and endoLL, the heterogeneous glycans on antibodies were fully transformed into homogeneous-GlcNAc by a combination of endoS, endoD, and endoLL. Next, the desired N-glycans (M3; Man3GlcNAc1, G0; GlcNAc2Man3GlcNAc1, G2; Gal2GlcNAc2Man3GlcNAc1, A2; NeuAc2Gal2GlcNAc2Man3GlcNAc1 were transferred from the corresponding oxazolines to the GlcNAc residue on the intact anti-Her2 antibody with an ENG'ase mutant (endoS-D233Q, and the glycoengineered anti-Her2 antibody was obtained. The binding assay of anti-Her2 antibody with homogenous N-glycans with FcγRIIIa-V158 showed that the glycoform influenced the affinity for FcγRIIIa-V158. In addition, the ADCC assay for the glycoengineered anti-Her2 antibody (mAb-M3, mAb-G0, mAb-G2, and mAb-A2 was performed using SKBR-3 and BT-474 as target

  4. Highly Efficient Syntheses of Hyaluronic Acid Oligosaccharides

    OpenAIRE

    Huang, Lijun; Huang, Xuefei

    2007-01-01

    Highly efficient syntheses of hyaluronic acid oligosaccharides have been accomplished through the pre-activation based iterative one-pot strategy. A series of oligosaccharides ranging from di- to hexasaccharides were rapidly assembled using only near stoichiometric amounts of the building blocks without aglycon adjustment or purifications of intermediate oligosaccharides. Deprote...

  5. Synthesizing Chaotic Maps with Prescribed Invariant Densities

    OpenAIRE

    Rogers, Alan; Shorten, Robert; Heffernan, Daniel M.

    2004-01-01

    The Inverse Frobenius-Perron problem (IFPP) concerns the creation of discrete chaotic mappings with arbitrary invariant densities. In this note, we present a new and elegant solution to the IFPP, based on positive matrix theory. Our method allows chaotic maps with arbitrary piecewise-constant invariant densities, and with arbitrary mixing properties, to be synthesized.

  6. Method and apparatus for synthesizing filamentary structures

    Science.gov (United States)

    Height, Murray J.; Howard, Jack B.; Vandersande, John B.

    2008-02-26

    Method and apparatus for producing filamentary structures. The structures include single-walled nanotubes. The method includes combusting hydrocarbon fuel and oxygen to establish a non-sooting flame and providing an unsupported catalyst to synthesize the filamentary structure in a post-flame region of the flame. Residence time is selected to favor filamentary structure growth.

  7. SYNTHESES AND PROPERTIES OF SOME ORGANOSILANE POLYMERS

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xinghua; Robert West

    1984-01-01

    Some organosilane polymers with high molecular weights have been synthesized by cocondensation of organosilicon dihalide monomers with sodium metal in toluene. These polymers are both soluble in common solvents and meltable at lower temperatures, and can be molded, cast into films or drawn into fibers. Exposure of the solid polymers to ultraviolet light leads to degradation or crosslinking.

  8. A Novel Method to Synthesize Polyorganozircosilazane

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new kind of polyorganozircosilazane as Si/Zr/C/N-based ceramic precursor was synthesized from the condensation reaction of hexamethylcyclotrisilazane lithium salts (D3NLi) and zirconium tetrachloride (ZrCl4). In the presence of N, N, N′, N′-tetramethyl ethylene diamine (TMEDA), polyorganozircosilazane was obtained in high yield.

  9. Syntheses of Arnottin I and Arnottin II

    OpenAIRE

    Moschitto, Matthew J.; Anthony, David R.; Lewis, Chad A.

    2015-01-01

    Short total syntheses of arnottin I and II were accomplished in 5 and 6 steps, respectively. A sesamol-benzyne cycloaddition with a 3-furyl-benzoate followed by regiospecific lactonization provided rapid, large-scale access to the core of arnottin I. Saponification of arnottin I and hypervalent iodide mediated spirocyclization provided an efficient and direct preparation of racemic arnottin II.

  10. The chemoenzymatic synthesis of clofarabine and related 2'-deoxyfluoroarabinosyl nucleosides: the electronic and stereochemical factors determining substrate recognition by E. coli nucleoside phosphorylases.

    Science.gov (United States)

    Fateev, Ilja V; Antonov, Konstantin V; Konstantinova, Irina D; Muravyova, Tatyana I; Seela, Frank; Esipov, Roman S; Miroshnikov, Anatoly I; Mikhailopulo, Igor A

    2014-01-01

    Two approaches to the synthesis of 2-chloro-9-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)adenine (1, clofarabine) were studied. The first approach consists in the chemical synthesis of 2-deoxy-2-fluoro-α-D-arabinofuranose-1-phosphate (12a, (2F)Ara-1P) via three step conversion of 1,3,5-tri-O-benzoyl-2-deoxy-2-fluoro-α-D-arabinofuranose (9) into the phosphate 12a without isolation of intermediary products. Condensation of 12a with 2-chloroadenine catalyzed by the recombinant E. coli purine nucleoside phosphorylase (PNP) resulted in the formation of clofarabine in 67% yield. The reaction was also studied with a number of purine bases (2-aminoadenine and hypoxanthine), their analogues (5-aza-7-deazaguanine and 8-aza-7-deazahypoxanthine) and thymine. The results were compared with those of a similar reaction with α-D-arabinofuranose-1-phosphate (13a, Ara-1P). Differences of the reactivity of various substrates were analyzed by ab initio calculations in terms of the electronic structure (natural purines vs analogues) and stereochemical features ((2F)Ara-1P vs Ara-1P) of the studied compounds to determine the substrate recognition by E. coli nucleoside phosphorylases. The second approach starts with the cascade one-pot enzymatic transformation of 2-deoxy-2-fluoro-D-arabinose into the phosphate 12a, followed by its condensation with 2-chloroadenine thereby affording clofarabine in ca. 48% yield in 24 h. The following recombinant E. coli enzymes catalyze the sequential conversion of 2-deoxy-2-fluoro-D-arabinose into the phosphate 12a: ribokinase (2-deoxy-2-fluoro-D-arabinofuranose-5-phosphate), phosphopentomutase (PPN; no 1,6-diphosphates of D-hexoses as co-factors required) (12a), and finally PNP. The substrate activities of D-arabinose, D-ribose and D-xylose in the similar cascade syntheses of the relevant 2-chloroadenine nucleosides were studied and compared with the activities of 2-deoxy-2-fluoro-D-arabinose. As expected, D-ribose exhibited the best substrate activity

  11. The chemoenzymatic synthesis of clofarabine and related 2′-deoxyfluoroarabinosyl nucleosides: the electronic and stereochemical factors determining substrate recognition by E. coli nucleoside phosphorylases

    Directory of Open Access Journals (Sweden)

    Ilja V. Fateev

    2014-07-01

    Full Text Available Two approaches to the synthesis of 2-chloro-9-(2-deoxy-2-fluoro-β-D-arabinofuranosyladenine (1, clofarabine were studied. The first approach consists in the chemical synthesis of 2-deoxy-2-fluoro-α-D-arabinofuranose-1-phosphate (12a, 2FAra-1P via three step conversion of 1,3,5-tri-O-benzoyl-2-deoxy-2-fluoro-α-D-arabinofuranose (9 into the phosphate 12a without isolation of intermediary products. Condensation of 12a with 2-chloroadenine catalyzed by the recombinant E. coli purine nucleoside phosphorylase (PNP resulted in the formation of clofarabine in 67% yield. The reaction was also studied with a number of purine bases (2-aminoadenine and hypoxanthine, their analogues (5-aza-7-deazaguanine and 8-aza-7-deazahypoxanthine and thymine. The results were compared with those of a similar reaction with α-D-arabinofuranose-1-phosphate (13a, Ara-1P. Differences of the reactivity of various substrates were analyzed by ab initio calculations in terms of the electronic structure (natural purines vs analogues and stereochemical features (2FAra-1P vs Ara-1P of the studied compounds to determine the substrate recognition by E. coli nucleoside phosphorylases. The second approach starts with the cascade one-pot enzymatic transformation of 2-deoxy-2-fluoro-D-arabinose into the phosphate 12a, followed by its condensation with 2-chloroadenine thereby affording clofarabine in ca. 48% yield in 24 h. The following recombinant E. coli enzymes catalyze the sequential conversion of 2-deoxy-2-fluoro-D-arabinose into the phosphate 12a: ribokinase (2-deoxy-2-fluoro-D-arabinofuranose-5-phosphate, phosphopentomutase (PPN; no 1,6-diphosphates of D-hexoses as co-factors required (12a, and finally PNP. The substrate activities of D-arabinose, D-ribose and D-xylose in the similar cascade syntheses of the relevant 2-chloroadenine nucleosides were studied and compared with the activities of 2-deoxy-2-fluoro-D-arabinose. As expected, D-ribose exhibited the best substrate

  12. Synthesizing Waves from Animated Height Fields

    DEFF Research Database (Denmark)

    Nielsen, Michael Bang; Söderström, Andreas; Bridson, Robert

    2013-01-01

    Computer animated ocean waves for feature films are typically carefully choreographed to match the vision of the director and to support the telling of the story. The rough shape of these waves is established in the previsualization (previs) stage, where artists use a variety of modeling tools...... with fast feedback to obtain the desired look. This poses a challenge to the effects artists who must subsequently match the locked-down look of the previs waves with high-quality simulated or synthesized waves, adding the detail necessary for the final shot. We propose a set of automated techniques...... for synthesizing Fourier-based ocean waves that match a previs input, allowing artists to quickly enhance the input wave animation with additional higher-frequency detail that moves consistently with the coarse waves, tweak the wave shapes to flatten troughs and sharpen peaks if desired (as is characteristic...

  13. Predictions of synthesizing element 119 and 120

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The evaporation residue cross sections of synthesizing superheavy nuclei Z=119, 120 are calculated by different sets of master equations with different dynamical variables. Two methods basically predicted similar results that the Ca induced hot fusion can 48 produce element 119 easier than produce 120, and the evaporation residue cross sections for 119 are detectable by current advanced techniques, while the evaporation residue cross sections are below 0.1 pb for producing element 120.

  14. Spurious in PLL-DDS frequency synthesizers

    Czech Academy of Sciences Publication Activity Database

    Kroupa, Věnceslav František; Štursa, Jarmil

    2002-01-01

    Roč. 2, č. 1 (2002), s. 48-51. ISSN 1335-8243. [Digital Signal Processing and Multimedia Communications DSP-MCOM 2001 /5./. Košice, 27.11.2001-29.11.2001] R&D Projects: GA ČR GA102/00/0958 Institutional research plan: CEZ:AV0Z2067918 Keywords : frequency synthesizers * phase locked loops * direct digital synthesis Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  15. Mechanismen der Laserablation zur Synthese nanoskopischer Kolloide

    OpenAIRE

    Schaumberg, Christian Alexander

    2016-01-01

    Die Synthese kolloidaler Nanopartikel ist daher eines der wichtigsten Forschungsthemen der letzten Jahre. Die gepulste Laserablation in Flüssigkeiten stellt eine Alternative zu den nasschemischen Synthesewegen dar. Merkmale der gepulsten Laserablation in Flüssigkeiten ist der geringe experimentelle Aufwand, die Vielseitigkeit und die Möglichkeit stabilisatorfreie kolloidale Nanopartikel herzustellen. Eine Weiterentwicklung ist die Verwendung von Pulversuspensionen als Ausgangsmaterial. Dies f...

  16. High pressure syntheses of carbonates. 6

    International Nuclear Information System (INIS)

    The ternary carbonates NaLn(CO3)2 with Ln = La to Lu and Y are synthesized by dehydration of NaLn(CO3)2.xH2O or by reaction of Na2CO3 with Ln2(C2O4)3.xH2O under 3000 bar CO2 and 350 - 500 0C. Two structures are found, characterized by IR and X-ray investigations and by thermal decomposition. (author)

  17. Synthese von cyclischen Disacchariden durch intramolekulare Glycosylierung

    OpenAIRE

    Claude, Patrick

    2005-01-01

    Organic chemists have always confronted the difficult task of synthesizing carbohydrates of with regio- and sterospecific specific glycosydic linkages, some of them frequently found in nature, with exert significant biological activities. To overcome this hurdle, they introduced an ingenuous synthetic method called "Intramolecular Glycosylation". Intramolecular glycosylation is the reaction between a glycosyl donor and acceptor that are both linked to a tether. The tether can be a tempora...

  18. Magnesioferrite synthesized from magnesian-magnetites

    Directory of Open Access Journals (Sweden)

    Marcelo Hidemassa Anami

    2014-02-01

    Full Text Available Magnesioferrite is an important mineral due to its use in different scientific fields and by the fact that the soil through the action of weathering, can be a source of nutrients essential for plant development by the fact that in the soil. Its use in pure form or associated with other minerals is only possible through the synthesis in laboratory conditions. This study aimed to synthesize magnesioferrite and hematite from magnesian-magnetite by a co-precipitation procedure. The methodology used is an adaptation of the method of synthesis of pure magnetite, partially replacing the soluble salts of iron with soluble magnesium salts in the proportion of 30.0 mol% of Fe for Mg. The characterization of the synthetic minerals used x-rays diffraction, total chemical analysis and mass specific magnetic susceptibility. The results showed that besides the magnesian-magnetite an unprecedented muskoxita was synthesized, which upon annealing was converted to magnesioferrite and hematite and in the proportion of 93.1% and 6.9% respectively. The isomorphous substitution of Fe for Mg enhanced the thermal stability of the ferrimagnetic mineral synthesized.

  19. Shock Syntheses of Novel Nitrides and Biomolecules

    Science.gov (United States)

    Sekine, Toshimori

    2013-06-01

    High-pressure spinel nitride of Si3N4 was discovered more than 10 years ago. Since then there have been many studies on the spinel nitrides and related materials including oxynitrides. We have developed shock synthesis method to investigate their structural, mechanical, chemical, physical, and optical properties. At the same time we tried to synthesize carbon nitrides from the organic substances. And later we extended to shock synthesis of ammonia through the Haber-Bosch reaction under shock in order to apply geochemical subjects related to the origin of life. The simplest amino acid of glycine, as well as animes (up to propylamine) and carboxylic acids (up to pentanoic acid), has been synthesized successfully in aqueous solutions through meteoritic impact reactions. Recently we are trying to make more complex biomolecules for implications of biomolecule formation for the origin of life through meteorite impacts on early Earth's ocean. These results of shock syntheses may imply significant contributions to materials science and Earth and planetary sciences. This research is collaborated with National Institute for Materials Science and Tohoku University.

  20. Syntheses and studies of acetylenic polymers

    Energy Technology Data Exchange (ETDEWEB)

    Yiwei, Ding

    1994-03-03

    Based on new diiodo aryl compounds a series of novel soluble polymers, poly(2,5-dialkoxy-1,4-phenyleneethynylene)s (PPE polymers) were synthesized using palladium-catalysis. The molecular weights (MW) range from 8,000 to 40,000. Properties such as absorption, fluorescence, and conductivity were studied. A PPE polymer with butoxy side chain exhibits a weak electrical conductivity ({sigma} = 10{sup {minus}3} S/cm) after doping with AsF{sub 5}. Absorption spectra in THF solution at room temperature (RT) show a maximum at 440 nm. However, absorption spectra of PPE polymers in the film state at (RT) show a maximum at 480 nm. PPE polymer-based light emitting diode (LED) devices have been prepared; greenish light from these LED devices can be observed. Poly(ethynylene-p-arylene-ethynylene-silylene)s were synthesized through the same palladium-catalyzed polymerization; MWs are between 6,000 and 82,000. Absorption and fluorescence were studied. Some of these polymers exhibit thermotropic liquid crystalline properties. In addition, nonlinear optical properties were briefly examined. Poly(silylene-ethynylene) homopolymers as well as alternating copolymers were synthesized through a novel palladium-catalyzed polymerization; MWs range from 56 {times} 10{sup 3} to 5.3 {times} 10{sup 3}. Thermal stability of these was also investigated; char yields range from 56 to 83%. One of these polymers exhibits thermotropic liquid crystalline properties.

  1. Synthese stereoskopischer Sequenzen aus 2-dimensionalen Videoaufnahmen

    OpenAIRE

    Knorr, Sebastian

    2008-01-01

    Die rasante Entwicklung der 3D-Technologie führt derzeit zu einer verstärkten Nachfrage nach 3D-Spielen, 3D-Filmen, 3D-Präsentationen und interaktiven 3D-Inhalten. Von der Motiviation getrieben, alte Filme als Neuauflage in 3D zu erleben, beschäftigt sich die vorliegende Dissertation mit der automatischen Konvertierung von Videosequenzen von 2D in stereoskopisch 3D. Zur Umsetzung dieses Ziels wird ein neues Verfahren zur realistischen Synthese stereoskopischer Ansichten (RSVS) aus monokularen...

  2. Biocompatibility of poly allylamine synthesized by plasma

    International Nuclear Information System (INIS)

    A study of the electric and hydrophilic properties of poly allylamine (PAI) synthesized by plasma whose structure contains N-H, C-H, C-O and O-H bonds is presented, that promote the biocompatibility with the human body. To study the PAI hydrolytic affinity, solutions of salt concentration similar to those of the human body were used. The results indicate that the solutions modify the charge balance in the surfaces reducing the hydrophobicity in the poly allylamine whose contact angle oscillates among 10 and 16 degrees and the liquid-solid surface tension between 4 and 8 dina/cm. (Author)

  3. Multimeric complexes among ankyrin-repeat and SOCS-box protein 9 (ASB9), ElonginBC, and Cullin 5: insights into the structure and assembly of ECS-type Cullin-RING E3 ubiquitin ligases.

    Science.gov (United States)

    Thomas, Jemima C; Matak-Vinkovic, Dijana; Van Molle, Inge; Ciulli, Alessio

    2013-08-01

    Proteins of the ankyrin-repeat and SOCS-box (ASB) family act as the substrate-recognition subunits of ECS-type (ElonginBC-Cullin-SOCS-box) Cullin RING E3 ubiquitin ligase (CRL) complexes that catalyze the specific polyubiquitination of cellular proteins to target them for degradation by the proteasome. Therefore, ASB multimeric complexes are involved in numerous cell processes and pathways; however, their interactions, assembly, and biological roles remain poorly understood. To enhance our understanding of ASB CRL systems, we investigated the structure, affinity, and assembly of the quaternary multisubunit complex formed by ASB9, Elongin B, Elongin C (EloBC), and Cullin 5. Here, we describe the application of several biophysical techniques including differential scanning fluorimetry, isothermal titration calorimetry (ITC), nanoelectrospray ionization, and ion-mobility mass spectrometry (IM-MS) to provide structural and thermodynamic information for a quaternary ASB CRL complex. We find that ASB9 is unstable alone but forms a stable ternary complex with EloBC that binds with high affinity to the Cullin 5 N-terminal domain (Cul5NTD) but not to Cul2NTD. The structure of the monomeric ASB9-EloBC-Cul5NTD quaternary complex is revealed by molecular modeling and is consistent with IM-MS and temperature-dependent ITC data. This is the first experimental study to validate structural information for the assembly of the quaternary N-terminal region of an ASB CRL complex. The results suggest that ASB E3 ligase complexes function and assemble in an analogous manner to that of other CRL systems and provide a platform for further molecular investigation of this important protein family. The data reported here will also be of use for the future development of chemical probes to examine the biological function and modulation of other ECS-type CRL systems. PMID:23837592

  4. Biogenic synthesized nanoparticles and their applications

    Science.gov (United States)

    Singh, Abhijeet; Sharma, Madan Mohan

    2016-05-01

    In the present scenario, there are growing concerns over the potential impacts of bioengineered nanoparticles in the health sector. However, our understanding of how bioengineered nanoparticles may affect organisms within natural ecosystems, lags far behind our rapidly increasing ability to engineer novel nanoparticles. To date, research on the biological impacts of bioengineered nanoparticles has primarily consisted of controlled lab studies of model organisms with single species in culture media. Here, we described a cost effective and environment friendly technique for green synthesis of silver nanoparticles. Silver nanoparticles were successfully synthesized from 1 mM AgNO3 via a green synthesis process using leaf extract as reducing as well as capping agent. Nanoparticles were characterized with the help of UV-vis absorption spectroscopy, X-ray diffraction and TEM analysis which revealed the size of nanoparticles of 30-40 nm size. Further the nanoparticles synthesized by green route are found highly toxic against pathogenic bacteria and plant pathogenic fungi viz. Escherichia coli, Pseudomonas syringae and Sclerotiniasclerotiorum. The most important outcome of this work will be the development of value-added products and protection of human health from pathogens viz., bacteria, virus, fungi etc.

  5. Enantioselective catalytic syntheses of alpha-branched chiral amines

    DEFF Research Database (Denmark)

    Brase, S.; Baumann, T.; Dahmen, S.;

    2007-01-01

    Chiral amines play a pivotal role in fine chemical and natural product syntheses and the design of novel materials.......Chiral amines play a pivotal role in fine chemical and natural product syntheses and the design of novel materials....

  6. PZT Powders Synthesized by Hydrothermal Method

    Directory of Open Access Journals (Sweden)

    ZHU Kong-Jun, ZHU Ren-Qiang, DONG Na-Na, GU Hong-Hui, QIU Jin-Hao, JI Hong-Li

    2012-05-01

    Full Text Available Lead zirconate titanate (PZT) powders with single―phase, cubic morphology and average size of 1 μm were synthesized using hydrothermal methods. Effects of KOH concentration, hydrothermal treatment time and Pb excess were investigated. The results show that KOH concentration has an important influence on the solid solubility of Pb ion in A―site of PZT perovskite structure. The concentration of Pb2+ vacancies increased with the increase of OH― concentration. However, this kind of deficiency could be compensated by adding more Pb ions in the raw materials, and more Pb ions were needed to add with higher alkaline concentration in the starting solution. But excessive compensation of Pb ions would result in the appearance of the second phase.

  7. Structure of the enzymatically synthesized fructan inulin

    International Nuclear Information System (INIS)

    Construction, purification and characterization of a fusion protein of maltose-binding protein of Escherichia coli and the fructosyltransferase of Streptococcus mutans is described. With the purified protein, in vitro synthesis of inulin was performed. The obtained polysaccharide was characterized by high-performance size-exclusion chromatography (HPSEC) and static light scattering (SLS) in dilute aqueous and dimethyl sulfoxide solution. For all samples very high molecular weights between 60x106 and 90x106 g/mol and a remarkable small polydispersity index of 1.1 have been determined. Small root-mean-square radii of gyration point to a compact conformation in dilute solution. No difference between native and enzymatically synthesized inulin was observed by X-ray powder diffraction and thermoanalysis of solid samples. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  8. Method and apparatus for synthesizing hydrocarbons

    Science.gov (United States)

    Colmenares, C.A.; Somorjai, G.A.; Maj, J.J.

    1983-06-21

    A method and apparatus for synthesizing a mixture of hydrocarbons having five carbons or less is disclosed. An equal molar ratio of CO and H/sub 2/ gases is caused to pass through a ThO/sub 2/ catalyst having a surface area of about 80 to 125 m/sup 2//g. The catalyst further includes Na present as a substitutional cation in an amount of about 5 to 10 atom %. At a temperature of about 340 to 360/sup 0/C, and at pressures of about 20 to 50 atm, CH/sub 3/OH is produced in an amount of about 90 wt % of the total hydrocarbon mixture, and comprised 1 mole % of the effluent gas.

  9. High pressure syntheses of carbonates. 4

    International Nuclear Information System (INIS)

    The ternary carbonates LiLn(CO3)2 with Ln = La to Lu and Y are synthesized from mixtures of Li2CO3 and Ln2(C2O4)3 . xH2O under 2000 bar CO2 and 500 0C. Two monoclinic types are found. They are characterized by IR and X-ray investigation and thermal decomposition. With the pressure of 200 bar and 550 0C one gets oxide-carbonates LiLnOCO3 with Ln = Sm to Lu and Y. All substances are of the same monoclinic type. Again they are characterized by IR and X-ray investigations and by thermal decomposition. The influence of the CO2 pressure and of the temperature on the formation of either LiLn(CO3)2 or LiLnOCO3 is investigated. (author)

  10. Methods for synthesizing metal oxide nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Sunkara, Mahendra Kumar; Kumar, Vivekanand; Kim, Jeong H.; Clark, Ezra Lee

    2016-08-09

    A method of synthesizing a metal oxide nanowire includes the steps of: combining an amount of a transition metal or a transition metal oxide with an amount of an alkali metal compound to produce a mixture; activating a plasma discharge reactor to create a plasma discharge; exposing the mixture to the plasma discharge for a first predetermined time period such that transition metal oxide nanowires are formed; contacting the transition metal oxide nanowires with an acid solution such that an alkali metal ion is exchanged for a hydrogen ion on each of the transition metal oxide nanowires; and exposing the transition metal oxide nanowires to the plasma discharge for a second predetermined time period to thermally anneal the transition metal oxide nanowires. Transition metal oxide nanowires produced using the synthesis methods described herein are also provided.

  11. National Gas Survey. Synthesized gaseous hydrocarbon fuels

    Energy Technology Data Exchange (ETDEWEB)

    None

    1978-06-01

    The supply-Technical Advisory Task Force-Synthesized Gaseous Hydrocarbon Fuels considered coal, hydrocarbon liquids, oil shales, tar sands, and bioconvertible materials as potential feedstocks for gaseous fuels. Current status of process technology for each feedstock was reviewed, economic evaluations including sensitivity analysis were made, and constraints for establishment of a synthesized gaseous hydrocarbon fuels industry considered. Process technology is presently available to manufacture gaseous hydrocarbon fuels from each of the feedstocks. In 1975 there were eleven liquid feedstock SNG plants in the United States having a capacity of 1.1 billion SCFD. There can be no contribution of SNG before 1982 from plants using feedstocks other than liquids because there are no plants in operation or under construction as of 1977. Costs for SNG are higher than current regulated prices for U.S. natural gas. Because of large reserves, coal is a prime feedstock candidate although there are major constraints in the area of coal leases, mining and water permits, and others. Commercial technology is available and several new gasification processes are under development. Oil shale is also a feedstock in large supply and commercial process technology is available. There are siting and permit constraints, and water availability may limit the ultimate size of an oil shale processing industry. Under projected conditions, bioconvertible materials are not expected to support the production of large quantities of pipeline quality gas during the next decade. Production of low or medium Btu gas from municipal solid wastes can be expected to be developed in urban areas in conjunction with savings in disposal costs. In the economic evaluations presented, the most significant factor for liquid feedstock plants is the anticipated cost of feedstock and fuel. The economic viability of plants using other feedstocks is primarily dependent upon capital requirements.

  12. Porous oxides synthesized by the combustion method

    International Nuclear Information System (INIS)

    The result of this work, seeks to be a contribution for the treatment of radioactive wastes, with base to the sorption properties that present those porous oxides, synthesized by a method that allows to increase the sorption capacity. The main objective of the present investigation has been the modification of the structural characteristics of the oxides of Fe, Mg and Zn to increase its capacity of sorption of 60 Co in particular. It was studied the effect of the synthesis method by combustion in the inorganic oxides; the obtained solids were characterized using the following techniques: X-ray diffraction (XRD), scanning electron microscopy (SEM), semiquantitative elementary analysis by Dispersive energy spectroscopy (EDS) and determination of surface area by the Brunauner-Emmett-Teller method (BET). Also was carried out batch type experiments for the sorption of Co2+, with the purpose of studying the sorption capacity of each one of the prepared oxides. In accordance with that previously exposed, the working plan that was carried out in this investigation is summarized in the following stages: 1. Preparation of inorganic oxides by two different methods, studying the effect of the temperature in the synthesis process. 2. Characterization of the inorganic oxides by XRD, by means of which those were chosen the solids with better properties. 3. Characterization of the inorganic oxides by SEM and EDS where it was studied the morphology of the synthesized materials and the semiquantitative elemental composition. 4. Realization of a sorption experiment type Batch with non radioactive Co2+ to simulate the sorption of 60 Co and determination of the sorption capacity by means of neutron activation of the non radioactive cobalt. 5. Determination of the surface area by the (BET) technique of the inorganic oxides with better sorption properties. (Author)

  13. Localization of ANP-synthesizing cells in rat stomach

    Institute of Scientific and Technical Information of China (English)

    Chun-Hui Li; Li-Hui Pan; Chun-Yu Li; Chang-Lin Zhu; Wen-Xie Xu

    2006-01-01

    AIM: To study the morphological positive expression of antrial natriuretic peptide (ANP)-synthesizing cells and ultrastructural localization and the relationship between ANP-synthesizing cells and microvessel density in the stomach of rats and to analyze the distribution of the three histologically distinct regions of ANP-synthesizing cells.METHODS: Using immunohistochemical techniques, we studied positive expression of ANP-synthesizing cells in rat stomach. A postembedding immunogold microscopy technique was used for ultrastructural localization of ANP-synthesizing cells. Microvessel density in the rat stomach was estimated using tannic acid-ferric chloride (TAFC) method staining. Distribution of ANP-synthesizing cells were studied in different regions of rat stomach histochemically.RESULTS: Positive expression of ANP-synthesizing cells were localized in the gastric mucosa of rats. Localization of ANP-synthesizing cells identified them to be enterochrochromaffin cells (EC) by using a postembedding immunogold electron microscopy technique. EC cells were in the basal third of the cardiac mucosa region.ANP-synthesizing cells existed in different regions of rat stomach and its density was largest in the gastric cardiac region, and the distribution order of ANP-synthesizing cells in density was cardiac region, pyloric region and fundic region in mucosa layer. We have also found a close relationship between ANP-synthesizing cells and microvessel density in gastric mucosa of rats using TAFC staining.CONCLUSION: ANP-synthesizing cells are expressed in the gastric mucosa. EC synthesize ANP. There is a close relationship between ANP-synthesizing cells and microvessel density in gastric mucosa of rats.The distribution density of ANP-synthesizing cells is largest in the gastric cardiac region.

  14. Chemical syntheses of inulin and levan structures.

    Science.gov (United States)

    Oscarson, Stefan; Sehgelmeble, Fernando W

    2002-11-29

    A fructofuranosyl thiglycoside donor, ethyl 6-O-acetyl-3-O-benzyl-1,4-O-(1,1,3,3-tetraisopropyldisiloxane-1,3-diyl)-2-thio-beta-D-fructofuranoside (11), designed to yield stereospecifically beta-linkages and also to allow subsequent elongation in the 6- and/or 1-positions, was prepared and used in syntheses of levan and inulin structures. DMTST-promoted glycosylation between 11 (1.3 mol equiv) and methyl beta-D-fructofuranoside 6-OH and 1-OH acceptors (3 and 6) gave stereospecifically the protected methyl levanobioside 12 and inulinobioside 17 in excellent yields (80 and 86%), respectively. Protecting group manipulations on these afforded new disaccharide 6'-OH and 1'-OH acceptors (13 and 19), which were coupled again with donor 11 (1.0 mol equiv) to yield methyl levanotrioside 14 and inulinotrioside 20 in high yields, 65 and 67%, respectively. These were transformed into new acceptors and also fully deprotected to afford the methyl glycosides of levanotriose and inulinotriose, all structures that have earlier not been accessible by chemical synthesis. PMID:12444625

  15. Syntheses of surfactants from oleochemical epoxides

    Directory of Open Access Journals (Sweden)

    Warwel Siegfried

    2001-01-01

    Full Text Available Sugar-based surfactants were obtained in good yields (up to 100% under mild conditions (70°C, methanol or mixtures of methanol and water by ring-opening of terminal epoxides with aminopolyols, derived from glucose. Reaction of N-methyl glucamine with epoxides from even-numbered C4-C18 alpha-olefins or from terminal unsaturated fatty acid methyl esters leads to linear products, while corresponding reactions with N-dodecyl glucamine or glucamine yield surfactants with different Y-structures. Products obtained by conversion of omega-epoxy fatty acid methyl esters were saponificated with NaOH or hydrolyzed enzymatically to sodium salts or free acids respectively, which are amphoteric surfactants. Studies of the surfactants at different pH-values demonstrate different surface active properties in aqueous solutions. Critical micelle concentrations (c.m.c. in a range between 2 and 500mg/l and surface tensions of 25-40mN/m were measured for several of the synthesized sugar-based surfactants. The ring-opening products are rather poor foamers, whereas some of the corresponding hydrobromides show good foaming properties.

  16. Legionella bozemanae synthesizes phosphatidylcholine from exogenous choline.

    Science.gov (United States)

    Palusinska-Szysz, Marta; Janczarek, Monika; Kalitynski, Rafal; Dawidowicz, Andrzej L; Russa, Ryszard

    2011-02-20

    The phospholipid class and fatty acid composition of Legionella bozemanae were determined using thin-layer chromatography, gas-liquid chromatography, and matrix-assisted laser desorption ionization-time of flight mass spectrometry. Phosphatidylcholine, phosphatidylethanolamine, and diphosphatidylglycerol were the predominant phospholipids, while phosphatidyl-N-monomethylethanolamine, phosphatidylglycerol, and phosphatidyl-N,N-dimethylethanolamine were present at low concentrations. With the use of the LC/MS technique, PC16:0/15:0, PC17:/15:0, and PE16:1/15:0 were shown to be the dominant phospholipid constituents, which may be taxonomically significant. Two independent phosphatidylcholine synthesis pathways (the three-step methylation and the one-step CDP-choline pathway) were present and functional in L. bozemanae. In the genome of L. bozemanae, genes encoding two potential phosphatidylcholine forming enzymes, phospholipid N-methyl transferase (PmtA) and phosphatidylcholine synthase (Pcs), homologous to L. longbeachae, L. drancourtii, and L. pneumophila pmtA and pcs genes were identified. Genes pmtA and pcs from L. bozemanae were sequenced and analyzed on nucleotide and amino acid levels. Bacteria grown on an artificial medium with labelled choline synthesized phosphatidylcholine predominantly via the phosphatidylcholine synthase pathway, which indicates that L. bozemanae phosphatidylcholine, similarly as in other bacteria associated with eukaryotes, is an important determinant of host-microbe interactions. PMID:20338739

  17. Multistep sintering to synthesize fast lithium garnets

    Science.gov (United States)

    Xu, Biyi; Duan, Huanan; Xia, Wenhao; Guo, Yiping; Kang, Hongmei; Li, Hua; Liu, Hezhou

    2016-01-01

    A multistep sintering schedule is developed to synthesize Li7La3Zr2O12 (LLZO) doped with 0.2 mol% Al3+. The effect of sintering steps on phase, relative density and ionic conductivity of Al-doped LLZO has been evaluated using powder X-Ray diffraction (XRD), scanning electron microscopy (SEM), 27Al magic spinning nuclear magnetic resonance (NMR) spectroscopy and electrochemical impedance spectroscopy (EIS). The results show that by holding the sample at 900 °C for 6 h, the mixture of tetragonal and cubic garnet phases are obtained; by continuously holding at 1100 °C for 6 h, the tetragonal phase completely transforms into cubic phase; by holding at 1200 °C, the relative density increases without decomposition of the cubic phase. The Al-LLZO pellets after multistep sintering exhibit cubic phase, relative density of 94.25% and ionic conductivity of 4.5 × 10-4 S cm-1 at room temperature. Based on the observation, a sintering model is proposed and discussed.

  18. Computational Models to Synthesize Human Walking

    Institute of Scientific and Technical Information of China (English)

    Lei Ren; David Howard; Laurence Kenney

    2006-01-01

    The synthesis of human walking is of great interest in biomechanics and biomimetic engineering due to its predictive capabilities and potential applications in clinical biomechanics, rehabilitation engineering and biomimetic robotics. In this paper,the various methods that have been used to synthesize humanwalking are reviewed from an engineering viewpoint. This involves a wide spectrum of approaches, from simple passive walking theories to large-scale computational models integrating the nervous, muscular and skeletal systems. These methods are roughly categorized under four headings: models inspired by the concept of a CPG (Central Pattern Generator), methods based on the principles of control engineering, predictive gait simulation using optimisation, and models inspired by passive walking theory. The shortcomings and advantages of these methods are examined, and future directions are discussed in the context of providing insights into the neural control objectives driving gait and improving the stability of the predicted gaits. Future advancements are likely to be motivated by improved understanding of neural control strategies and the subtle complexities of the musculoskeletal system during human locomotion. It is only a matter of time before predictive gait models become a practical and valuable tool in clinical diagnosis, rehabilitation engineering and robotics.

  19. Mechanochemically Driven Syntheses of Boride Nanomaterials

    Science.gov (United States)

    Blair, Richard G.

    Solid state metathesis reactions have proven to be a viable route to the production of unfunctionalized nanomaterials. However, current implementations of this approach are limited to self-propagating reactions. We have been investigating mechanically driven metathesis reactions. The use of high-energy ball mills allows control of crystallite sizes without the use of a capping group. Reinforcement materials with crystallite sizes on the order of 5-30 nm can be produced in such a manner. Borides are of particular interest due to their strength, high melting point, and electrical conductivity. The ultimate goal of this work is to prepare oxide and capping group-free nanoparticles suitable for incorporation in thermoelectric, polymer, and ceramic composites. Ultimately this work will facilitate the production of improved thermoelectric materials that will provide robust, deployable, power generation modules to supplement or replace fuel cell, Stirling, and battery-derived power sources. It will also result in scalable, bulk syntheses of tough, refractory, conductive nanomaterials for polymer composites with improved electrical properties, ceramic composites with enhanced fracture toughness, and composites with enhanced neutron reflectance and/or absorbance.

  20. Recent progress at the Petawatt Field Synthesizer

    Energy Technology Data Exchange (ETDEWEB)

    Skrobol, Christoph; Major, Zsuzsanna; Krausz, Ferenc; Karsch, Stefan [Max-Planck-Institut fuer Quantenoptik, Garching (Germany); Department fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, Garching (Germany); Klingebiel, Sandro; Wandt, Christoph; Ahmad, Izhar; Siebold, Mathias; Trushin, Sergei A. [Max-Planck-Institut fuer Quantenoptik, Garching (Germany)

    2010-07-01

    The Petawatt Field Synthesizer (PFS) aims at delivering wave-form controlled, few-cycle laser pulses with petawatt-scale peak power. The PFS design is based on a modified scheme of optical parametric chirped pulse amplification (OPCPA), where short pulses (of the order of 1 ps) are used for both pumping and seeding. The broadband seed pulses (700-1400 nm) are amplified in a series of DKDP crystals, pumped by 515 nm pulses with a total energy of 15-20 J at a repetition rate of 10 Hz. The chirped pulse amplifier chain of the pump laser uses diode pumping and Yb:YAG as the gain material in order to support the 1 ps pulse duration. To ensure a high level of synchronization between pump and seed pulses (< 100 fs), both are derived from a common frontend and are thereby inherently optically synchronized. However, along the large optical path difference between the seed and the pump chain additional temporal jitter can be accumulated, which is detrimental to the short-pulse OPCPA scheme. After an introduction to the PFS system, we report on our recent progress in identifying and eliminating the sources of timing jitter in preparation for the OPCPA stages.

  1. Recent progress at the Petawatt Field Synthesizer

    International Nuclear Information System (INIS)

    The Petawatt Field Synthesizer (PFS) aims at delivering wave-form controlled, few-cycle laser pulses with petawatt-scale peak power. The PFS design is based on a modified scheme of optical parametric chirped pulse amplification (OPCPA), where short pulses (of the order of 1 ps) are used for both pumping and seeding. The broadband seed pulses (700-1400 nm) are amplified in a series of DKDP crystals, pumped by 515 nm pulses with a total energy of 15-20 J at a repetition rate of 10 Hz. The chirped pulse amplifier chain of the pump laser uses diode pumping and Yb:YAG as the gain material in order to support the 1 ps pulse duration. To ensure a high level of synchronization between pump and seed pulses (< 100 fs), both are derived from a common frontend and are thereby inherently optically synchronized. However, along the large optical path difference between the seed and the pump chain additional temporal jitter can be accumulated, which is detrimental to the short-pulse OPCPA scheme. After an introduction to the PFS system, we report on our recent progress in identifying and eliminating the sources of timing jitter in preparation for the OPCPA stages.

  2. Study of photoconductor polymers synthesized by plasma

    International Nuclear Information System (INIS)

    In this work the photoconductivity in poly thiophene (PTh), poly pyrrole (PPy) and doped poly pyrrole with iodine (PPy/I) is studied, whose structures depend of the intensity of the electric field applied during the synthesis by plasma. The conjugated organic polymers possess double alternated bonds in its chemical structure that its allow the one movement of π electrons through the polymeric chains. The plasma is produced by means of splendor discharges to 13.5 MHz, resistive coupling, at one pressure that oscillates in the interval from 2 to 3x10-1 mbar, 180 min and powers of 10, 24, 40, 60, 80 and 100 W. Its were used heteroaromatic polymers like PTh and PPy/I, due to their potential applications in optoelectronics. The influence of the iodine is evaluated as dopant in PPy and it is compared with their similar one without doping in the light absorption/emission processes. The polymers synthesized by plasma can ramify or to intersect due to the energy applied during the synthesis. However, if the polymer intersects, the aromaticity can continue through the polymeric chains. The absorptions obtained by infrared spectroscopy, suggest that the polymer conserves the aromatic structure of the monomer fundamentally with substitutions that indicate inter crossing and partial fragmentation. The structure of most of the polymers spreads to be amorphous because they don't possess any classification. However, the PPy/I and PTh synthesized by this technique present crystalline segments whose intensity diminishes with the power of the discharge. In PTh, the average crystallinity diminishes from 19.8% to 9.9%, and in PPy/I of 15.9% to 13.3% in the interval of 10 to 100 W of power. In this work, however, its were crystalline arrangements in all the studied powers. The classification of the polymeric structure favors the formation of trajectories of transfer of electric loads among the chains, that which influences in the global electric conductivity of the material. In UV

  3. Syntheses of dopa glycosides using glucosidases.

    Science.gov (United States)

    Sivakumar, Ramaiah; Ponrasu, Thangavel; Divakar, Soundar

    2009-02-01

    Syntheses of L: -dopa 1a glucoside 10a,b and DL: -dopa 1b glycosides 10-18 with D: -glucose 2, D: -galactose 3, D: -mannose 4, D: -fructose 5, D: -arabinose 6, lactose 7, D: -sorbitol 8 and D: -mannitol 9 were carried out using amyloglucosidase from Rhizopus mold, beta-glucosidase isolated from sweet almond and immobilized beta-glucosidase. Invariably, L: -dopa and DL: -dopa gave low to good yields of glycosides 10-18 at 12-49% range and only mono glycosylated products were detected through glycosylation/arylation at the third or fourth OH positions of L: -dopa 1a and DL: -dopa 1b. Amyloglucosidase showed selectivity with D: -mannose 4 to give 4-O-C1beta and D: -sorbitol 8 to give 4-O-C6-O-arylated product. beta-Glucosidase exhibited selectivity with D: -mannose 4 to give 4-O-C1beta and lactose 7 to give 4-O-C1beta product. Immobilized beta-glucosidase did not show any selectivity. Antioxidant and angiotensin converting enzyme inhibition (ACE) activities of the glycosides were evaluated glycosides, out of which L: -3-hydroxy-4-O-(beta-D: -galactopyranosyl-(1'-->4)beta-D: -glucopyranosyl) phenylalanine 16 at 0.9 +/- 0.05 mM and DL: -3-hydroxy-4-O-(beta-D: -glucopyranosyl) phenylalanine 11b,c at 0.98 +/- 0.05 mM showed the best IC(50) values for antioxidant activity and DL: -3-hydroxy-4-O-(6-D: -sorbitol)phenylalanine 17 at 0.56 +/- 0.03 mM, L: -dopa-D: -glucoside 10a,b at 1.1 +/- 0.06 mM and DL: -3-hydroxy-4-O-(D: -glucopyranosyl)phenylalanine 11a-d at 1.2 +/- 0.06 mM exhibited the best IC(50) values for ACE inhibition. PMID:18712474

  4. Syntheses and electronic structures of decamethylmetallocenes

    International Nuclear Information System (INIS)

    The synthesis of decamethylmanganocene [(eta-C5(CH3)5)2Mn or (Me5Cp)2Mn)] is described. Magnetic susceptibility and electron paramagnetic resonance (EPR) studies show that (Me5Cp)2Mn is a low-spin, 17-electron compound with an orbitally degenerate, 2E/sub 2g/ [e/sub 2g/3 a/sub 1g/2] ground state. An x-ray crystallographic study of (Me5Cp)2Mn shows that it is a monomeric, D/sub 5d/ decamethylmetallocene with metal to ring carbon distances that are about 0.3 A shorter than those determined for high-spin manganocenes. The syntheses of new (Me5Cp)2M (M = Mg,V,Cr,Co, and Ni) and [(Me5Cp)2M]PF6 (M = Cr,Co, and Ni) compounds are described. In addition, a preparative route to a novel, dicationic decamethylmetallocene, [(Me5Cp)2Ni](PF6)2 is reported. Infrared, nuclear magnetic resonance, magnetic susceptibility, and/or x-ray crystallographic studies indicate that all the above compounds are D/sub 5d/ or D/sub 5h/ decamethylmetallocenes with low-spin electronic configurations. Cyclic voltammetry studies verify the reversibility and the one-electron nature of the (Me5Cp)2M → [(Me5Cp)2M]+ (M = Cr,Mn,Fe,Co,Ni), [(Me5Cp)2Mn]- → (Me5Cp)2Mn and [(Me5Cp)2Ni]+ → [Me5Cp)2Ni]2+ redox reactions. These studies reveal that the neutral decamethylmetallocenes are much more easily oxidized than their metallocene counterparts. This result attests to the electron-donating properties of the ten substituent methyl groups. Proton and carbon-13 NMR data are reported for the diamagnetic Mg(II), Mn(I), Fe(II), Co(III), and Ni(IV) decamethylmetallocenes and for [(Me5Cp)2V(CO)2]+. The uv-visible absorption spectra of the 15-, 18- and 20- electron decamethylmetallocenes are also reported

  5. Syntheses and electronic structures of decamethylmetallocenes

    Energy Technology Data Exchange (ETDEWEB)

    Robbins, J.L.

    1981-04-01

    The synthesis of decamethylmanganocene ((eta-C/sub 5/(CH/sub 3/)/sub 5/)/sub 2/Mn or (Me/sub 5/Cp)/sub 2/Mn)) is described. Magnetic susceptibility and electron paramagnetic resonance (EPR) studies show that (Me/sub 5/Cp)/sub 2/Mn is a low-spin, 17-electron compound with an orbitally degenerate, /sup 2/E/sub 2g/ (e/sub 2g//sup 3/ a/sub 1g//sup 2/) ground state. An x-ray crystallographic study of (Me/sub 5/Cp)/sub 2/Mn shows that it is a monomeric, D/sub 5d/ decamethylmetallocene with metal to ring carbon distances that are about 0.3 A shorter than those determined for high-spin manganocenes. The syntheses of new (Me/sub 5/Cp)/sub 2/M (M = Mg,V,Cr,Co, and Ni) and ((Me/sub 5/Cp)/sub 2/M)PF/sub 6/ (M = Cr,Co, and Ni) compounds are described. In addition, a preparative route to a novel, dicationic decamethylmetallocene, ((Me/sub 5/Cp)/sub 2/Ni)(PF/sub 6/)/sub 2/ is reported. Infrared, nuclear magnetic resonance, magnetic susceptibility, and/or x-ray crystallographic studies indicate that all the above compounds are D/sub 5d/ or D/sub 5h/ decamethylmetallocenes with low-spin electronic configurations. Cyclic voltammetry studies verify the reversibility and the one-electron nature of the (Me/sub 5/Cp)/sub 2/M ..-->.. ((Me/sub 5/Cp)/sub 2/M)/sup +/ (M = Cr,Mn,Fe,Co,Ni), ((Me/sub 5/Cp)/sub 2/Mn)/sup -/ ..-->.. (Me/sub 5/Cp)/sub 2/Mn and ((Me/sub 5/Cp)/sub 2/Ni)/sup +/ ..-->.. (Me/sub 5/Cp)/sub 2/Ni)/sup 2 +/ redox reactions. These studies reveal that the neutral decamethylmetallocenes are much more easily oxidized than their metallocene counterparts. This result attests to the electron-donating properties of the ten substituent methyl groups. Proton and carbon-13 NMR data are reported for the diamagnetic Mg(II), Mn(I), Fe(II), Co(III), and Ni(IV) decamethylmetallocenes and for ((Me/sub 5/Cp)/sub 2/V(CO)/sub 2/)/sup +/. The uv-visible absorption spectra of the 15-, 18- and 20- electron decamethylmetallocenes are also reported.

  6. Synthesizing Smart Polymeric and Composite Materials

    Science.gov (United States)

    Gong, Chaokun

    ,1-phenylene)bismaleimide (MDPB). It showed the same healing ability as 2MEP4F while all starting materials are cheaper and commercially available. To further improve the mechanical strength of the PFA-MDPB healable polymer, epoxy as a strengthening component was mixed with PFA-MDPB healable polymer. The PFA, MDPB and epoxy composite polymers were further reinforced by carbon fiber as done with 2MEP4F matrix and the final composites were proved to have higher short beam shear strength than 2MEP4F while exhibiting a similar healing efficiency. Healable polymer MDPB (a two maleimide groups monomer) -- FGEEDR (a four furan groups monomer) was also designed and synthesized for transparent healable polymer. The MDPB-FGEEDR healable polymer was composited with silver nanowires (AgNWs) to afford healable transparent composite conductor. Razer blade cuts in the composite conductor could heal upon heating to recover the mechanical strength and electrical conductivity of the composite. The healing could be repeated for multiple times on the same cut location. The healing process was as fast as 3 minutes for conductivity to recover 97% of the original value. For electroactive polymer polypyrrole, the fast volume change upon electrical field change due to electrochemical oxidization or reduction was studied for actuation targeting toward a robotic application. The flexibility of polypyrrole was improved via copolymerization with pyrrole derivatives. Actuator devices are fabricated that more suitable for implantable medical device application than pyrrole homopolymer. The change of dipole re-orientation and thus dielectric constant of ferroelectric polymers and ceramics upon electrical field may be exploited for electrocaloric effect (ECE) and solid state refrigeration. For ferroelectric ceramics, we synthesized a series of Ba1-xSrxTiO3 nanoparticles with diameter ranging from 8-12 nm and characterized their dielectric and ferroelectric properties through hysteresis measurement. It was

  7. Stereoselective chemoenzymatic synthesis of the four stereoisomers of l-2-(2-carboxycyclobutyl)glycine and pharmacological characterization at human excitatory amino acid transporter subtypes 1, 2, and 3

    DEFF Research Database (Denmark)

    Faure, Sophie; Jensen, Anders A.; Maurat, Vincent; Gu, Xin; Sagot, Emmanuelle; Aitken, David J; Bolte, Jean; Gefflaut, Thierry; Bunch, Lennart

    2006-01-01

    The four stereoisomers of l-2-(2-carboxycyclobutyl)glycine, l-CBG-I, l-CBG-II, l-CBG-III, and l-CBG-IV, were synthesized in good yield and high enantiomeric excess, from the corresponding cis and trans-2-oxalylcyclobutanecarboxylic acids 5 and 6 using the enzymes aspartate aminotransferase (AAT...

  8. Syntheses of (±-Romucosine and (±-Cathafiline

    Directory of Open Access Journals (Sweden)

    Surachai Nimgirawath

    2006-11-01

    Full Text Available The structures previously assigned to (--romucosine and (+-cathafiline, N-(methoxycarbonyl aporphine alkaloids from Rollina mucosa (Annonaceae and Cassytha filiformis (Lauraceae respectively, have been confirmed by total syntheses of the racemic substances. The key step of the syntheses involved formation of ring C of the aporphines by a radical-initiated cyclisation.

  9. Low noise frequency synthesizer of a centimeter range wave

    Directory of Open Access Journals (Sweden)

    I. S. Tsvelikh

    2007-06-01

    Full Text Available A highly stable, low noise 10.7 GHz frequency synthesizer for radio-relay link transceiver is presented. The basic elements of synthesizer are electrically tuned 5.35 GHz dielectric ring oscillator and transistor frequency doubler.

  10. Synthesis of DOTA-conjugated multimeric [Tyr3]octreotide peptides via a combination of Cu(I)-catalyzed "click" cycloaddition and thio acid/sulfonyl azide "sulfo-click" amidation and their in vivo evaluation.

    NARCIS (Netherlands)

    Yim, C.B.; Dijkgraaf, I.; Merkx, R.; Versluis, C.; Eek, A.; Mulder, G.E.; Rijkers, D.T.; Boerman, O.C.; Liskamp, R.M.

    2010-01-01

    Herein, we describe the design, synthesis, and biological evaluation of a series of DOTA-conjugated monomeric, dimeric, and tetrameric [Tyr(3)]octreotide-based analogues as a tool for tumor imaging and/or radionuclide therapy. These compounds were synthesized using a Cu(I)-catalyzed 1,3-dipolar cycl

  11. Assessment voice synthesizers for reading in digital books

    Directory of Open Access Journals (Sweden)

    Sérvulo Fernandes da Silva Neto

    2013-07-01

    Full Text Available The digital accessibility shows ways to information access in digital media that assist people with different types of disabilities to a better interaction with the computer independent of its limitations. Of these tools are composed by voice synthesizers, that supposedly simplifying their access to any recorded knowledge through digital technologies. However such tools have emerged originally in countries foreign language. Which brings us to the following research problem: the voice synthesizers are appropriate for reading digital books in the Portuguese language? The objective of this study was to analyze and classify different software tools voice synthesizers in combination with software digital book readers to support accessibility to e-books in Portuguese. Through literature review were identified applications software voice synthesizers, composing the sample analyzed in this work. We used a simplified version of the method of Multiple Criteria Decision Support - MMDA, to assess these. In the research 12 were considered readers of e-books and 11 software voice synthesizer, tested with six formats of e-books (E-pub, PDF, HTML, DOC, TXT, and Mobi. In accordance with the results, the software Virtual Vision achieved the highest score. Relative to formats, it was found that the PDF has measured a better score when summed the results of the three synthesizers. In the studied universe contacted that many synthesizers simply cannot be used because they did not support the Portuguese language.

  12. A terminal molybdenum arsenide complex synthesized from yellow arsenic.

    Science.gov (United States)

    Curley, John J; Piro, Nicholas A; Cummins, Christopher C

    2009-10-19

    A terminal molybdenum arsenide complex is synthesized in one step from the reactive As(4) molecule. The properties of this complex with its arsenic atom ligand are discussed in relation to the analogous nitride and phosphide complexes. PMID:19764796

  13. GaN Nanowires Synthesized by Electroless Etching Method

    KAUST Repository

    Najar, Adel

    2012-01-01

    Ultra-long Gallium Nitride Nanowires is synthesized via metal-electroless etching method. The morphologies and optical properties of GaN NWs show a single crystal GaN with hexagonal Wurtzite structure and high luminescence properties.

  14. Renewable nanocomposite polymer foams synthesized from Pickering emulsion templates

    OpenAIRE

    Blaker, J.J.; Lee, K-Y; Li, X; Menner, A.; Bismarck, A.

    2009-01-01

    Fully renewable macroporous thermosetting and UV-cured cellulose nanocomposites have been synthesized from medium and high internal phase water-in-acrylated soybean oil emulsions stabilized solely by hydrophobized bacterial cellulose nano-fibrils.

  15. Thermotoga lettingae Can Salvage Cobinamide To Synthesize Vitamin B12

    OpenAIRE

    Butzin, Nicholas C.; Secinaro, Michael A.; Swithers, Kristen S.; Gogarten, J Peter; Noll, Kenneth M.

    2013-01-01

    We recently reported that the Thermotogales acquired the ability to synthesize vitamin B12 by acquisition of genes from two distantly related lineages, Archaea and Firmicutes (K. S. Swithers et al., Genome Biol. Evol. 4:730–739, 2012). Ancestral state reconstruction suggested that the cobinamide salvage gene cluster was present in the Thermotogales' most recent common ancestor. We also predicted that Thermotoga lettingae could not synthesize B12 de novo but could use the cobinamide salvage...

  16. Synthese und Charakterisierung aromatischer periodisch mesoporöser Organosilicas

    OpenAIRE

    Morell, Jürgen

    2008-01-01

    Die zugrunde liegende Arbeit befasst sich mit der Synthese und Charakterisierung aromatischer periodisch mesoporöser Organosilicas. Neben der Untersuchung des Bildungsmechanismus Biphenyl-verbrückter PMO-Materialien durch in situ-SAXS-Messungen wurden eine Reihe Thiophen-verbrückter PMOs unter Verwendung verschiedener Tenside als Strukturdirektoren synthetisiert. Es konnten so 2D-hexagonale sowie kubische Produkte erhalten werden. Des Weiteren konnte die Synthese von bifunktionellen PMO-Mat...

  17. Proteins synthesized in tobacco mosaic virus infected protoplasts

    International Nuclear Information System (INIS)

    The author deals with research on the multiplication of tobacco mosaic virus (TMV) in leaf cell protoplasts. An attempt is made to answer three questions: (1) Which proteins are synthesized in TMV infected protoplasts as a result of TMV multiplication. (2) Which of the synthesized proteins are made under the direction of the TMV genome and, if any, which of the proteins are host specific. (3) In which functions are these proteins involved. (Auth.)

  18. Rhythmic Patterns and Literary Genres in Synthesized Speech

    OpenAIRE

    Delais-Roussarie, Elisabeth; Lolive, Damien; Yoo, Hiyon; Guennec, David

    2016-01-01

    International audience In this paper, the rhythmic patterns observed in natural and synthesized speech are compared for three literary forms (rhymes, poems, and fairy tales). The aim of the comparison is to evaluate how rhythm could be improved in synthesized speech, which could allow adapting it to specific styles or genres.The study is based on the analysis of a corpus of six rhymes, four poems and two extracts from fairy tales. All texts were recorded by three speakers and were generate...

  19. Antimicrobial activity of silver nanoparticles synthesized via green chemistry

    OpenAIRE

    KAVAZ DOGA; LAMIDO SURAYYA MUHAMMAD; UMAR HUZAIFA

    2015-01-01

    Silver nanoparticles (AgNPs) synthesis is among the new areas of nanotechnological research and it’s a bit cost effective, pollution free and environmental friendly compared to other metals used to synthesized nanoparticles. The synthesized nanoparticle was characterized using Atomic Force Microscope (AFM), FTIR, EDX, UV-Vis, Zeta Sizer and anti-microbial activity studies was also carried out. These techniques of identification were for morphological, particle size and concentration of NPs fo...

  20. Mechanism of the industrial enterprises marketing communication synthesized effect formation

    Directory of Open Access Journals (Sweden)

    Ya.O. Tymokhina

    2014-09-01

    Full Text Available The aim of the article. The main purpose of the article is to propose mechanism of the industrial enterprises marketing communication (MC synthesized effect formation. An indispensable component of MC mechanism synthesized effect of industrial enterprise is the legislation that governs use of synthesized marketing communications and obtaines synthesized effect from using them. It can be divided into three groups: legislation that regulates entrepreneurial activities, legislation governing communication activities, legislation governing innovation activities. Legislation of Ukraine regulating communication activities needs to be clarified in regulation of using the latest MC tools, features of their combination, rules of their using and order of action in violation case of applicable law. The results of the analysis. Any economic activity of enterprises governed by principles that are divided into general and specific by the level of coverage. The proposed set of formation principles of synthesized effect are principles of systematic using that focus on the result and periodicity which refer to general. Within the principle of periodicity it should consider principles that characterize each level of management that are such principles as using synthesis, using synergy and complexity. Functions of synthesized effect that are subject to general principles of economic analysis are: searching, score, analysis and accounting. Essence of specific features of MC synthesized effect consists the following positions: planning function, integration function, communicative function, synthesis implementation function. Mechanism formation MC synthesized effect of industrial enterprise is a set of systems that are used in process of its creation by management levels that reflects subject-object relationship between these systems. Input elements system form factors of external and internal environment, information about which enterprise collects through market

  1. A low-power CMOS frequency synthesizer for GPS receivers

    International Nuclear Information System (INIS)

    A low-power frequency synthesizer for GPS/Galileo L1/E1 band receivers implemented in a 0.18 μm CMOS process is introduced. By adding clock-controlled transistors at latch outputs to reduce the time constant at sensing time, the working frequency of the high-speed source-coupled logic prescaler supplying quadrature local oscillator signals has been increased, compared with traditional prescalers. Measurement results show that this synthesizer achieves an in-band phase noise of -87 dBc/Hz at 15 kHz offset, with spurs less than -65 dBc. The whole synthesizer consumes 6 mA in the case of a 1.8 V supply, and its core area is 0.6 mm2. (semiconductor integrated circuits)

  2. FRACTIONAL-N FREQUENCY SYNTHESIZER DESIGN FOR RFAPPLICATIONS

    Directory of Open Access Journals (Sweden)

    MUDASSAR I. Y. MEER

    2011-11-01

    Full Text Available In this work, design of Fractional-N Frequency Synthesizer using PLL has been investigated. The simulation is done in 0.18 μm CMOS technology with CADENCE tools using UMC foundry models. The different parts of synthesizer discussed in detail. Three different phase detector architectures are implemented. High speed TSPC DFF has designed to divide the frequency of GHz range. The prescalar is modified to have a delay of 80 ps only.For VCO, a multi layer inductor is used to save the area. The phase noise can be further reduced with a ΔΣ modulator in feedback loop. The designed frequency synthesizer targets RF applications like DVB-SH, WLAN,802.11, bluetooth, cordless phones and remote control.

  3. Monodisperse Silver Nanoparticles Synthesized by a Microwave-Assisted Method

    Institute of Scientific and Technical Information of China (English)

    ZHU Shao-Peng; TANG Shao-Chun; MENG Xiang-Kang

    2009-01-01

    Silver nanoparticles with an average size of about 2Onto are synthesized in a colloidal solution with the aid of microwave irradiation. Neither additional reductant nor stabilizer is required in this microwave-assisted method.The color of the colloidal solution is found to be dark green, different from the characteristic yellow of silver colloidal solutions. The silver nanoparticles in the colloidal solution have a narrow size distribution and large yield quantity. UV-visible absorption spectroscopy analysis reveals that the as-synthesized monodisperse silver nanoparticles have exceptional optical properties. Raman spectroscopy measurements demonstrate that these silver nanoparticles exhibit a notable surface-enhanced Raman scattering ability.

  4. Zinc Oxide Nano crystals Synthesized by Quenching Technique

    International Nuclear Information System (INIS)

    This paper reports an attempt to synthesize non toxic zinc oxide (ZnO) nano crystals using a simple quenching technique. The hot zinc oxide powder was quenched in hexane solution to obtain ZnO nano crystals. As the result, diameter size of the synthesized ZnO is 200 nm. It was also exhibited a good crystalline with wurtzite phase. The nano crystals properties of ZnO were revealed from good absorbance and green luminescence under UV exposure. This may be related with oxygen vacancy ionization during the annealing process. (author)

  5. Chemical phase analysis of seed mediated synthesized anisotropic silver nanoparticles

    Science.gov (United States)

    Bharti, Amardeep; Singh, Suman; Singla, M. L.; Goyal, Navdeep

    2015-08-01

    Noble-metal nanoparticles are of great interest because of its broad applications almost in every stream (i.e. biology, chemistry and engineering) due to their unique size/shape dependant properties. In this paper, chemical phase of seed mediated synthesized anisotropic silver nanoparticle (AgNPs) has been investigated via fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). These nanaoparticles were synthesized by seed-growth method controlled by urea and dextrose results to highly stable 12-20 nm particle size revealed by zeta potential and transmission electron microscopy (TEM).

  6. Chemical phase analysis of seed mediated synthesized anisotropic silver nanoparticles

    International Nuclear Information System (INIS)

    Noble-metal nanoparticles are of great interest because of its broad applications almost in every stream (i.e. biology, chemistry and engineering) due to their unique size/shape dependant properties. In this paper, chemical phase of seed mediated synthesized anisotropic silver nanoparticle (AgNPs) has been investigated via fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). These nanaoparticles were synthesized by seed-growth method controlled by urea and dextrose results to highly stable 12-20 nm particle size revealed by zeta potential and transmission electron microscopy (TEM)

  7. Copper nanoparticles synthesized in polymers by ion implantation

    DEFF Research Database (Denmark)

    Popok, Vladimir; Nuzhdin, Vladimir; Valeev, Valerij; Stepanov, Andrei

    2015-01-01

    Polymethylmethacrylate (PMMA) and polyimide (PI) samples are implanted by 40 keV Cu+ ions with high fluences in order to synthesize copper nanoparticles in shallow polymer layers. The produced metal/polymer nanocomposites are studied using atomic force and scanning electron microscopies as well as...... optical transmission spectroscopy. It is found that copper nanoparticles nucleation and growth are strongly fluence dependent as well as they are affected by the polymer properties, in particular, by radiation stability yielding different nanostructures for the implanted PI and PMMA. Shallow synthesized...

  8. Parametric Audio Based Decoder and Music Synthesizer for Mobile Applications

    NARCIS (Netherlands)

    Oomen, A.W.J.; Szczerba, M.Z.; Therssen, D.

    2011-01-01

    This paper reviews parametric audio coders and discusses novel technologies introduced in a low-complexity, low-power consumption audiodecoder and music synthesizer platform developed by the authors. Thedecoder uses parametric coding scheme based on the MPEG-4 Parametric Audio standard. In order to

  9. Antibacterial activity of silver nanoparticles synthesized from serine

    Energy Technology Data Exchange (ETDEWEB)

    Jayaprakash, N. [Catalysis and Nanomaterials Research Laboratory, Department of Chemistry, Loyola College, Chennai 600 034 (India); SRM Valliammai Engineering College, Department of Chemistry, Chennai 603 203 (India); Judith Vijaya, J., E-mail: jjvijayaloyola@yahoo.co.in [Catalysis and Nanomaterials Research Laboratory, Department of Chemistry, Loyola College, Chennai 600 034 (India); John Kennedy, L. [Materials Division, School of Advanced Sciences, VIT University, Chennai Campus, Chennai 600 048 (India); Priadharsini, K.; Palani, P. [Department of Center for Advanced Study in Botany, University of Madras, Guindy Campus, Chennai 600 025 (India)

    2015-04-01

    Silver nanoparticles (Ag NPs) were synthesized by a simple microwave irradiation method using polyvinyl pyrrolidone (PVP) as a capping agent and serine as a reducing agent. UV–Visible spectra were used to confirm the formation of Ag NPs by observing the surface plasmon resonance (SPR) band at 443 nm. The emission spectrum of Ag NPs showed an emission band at 484 nm. In the presence of microwave radiation, serine acts as a reducing agent, which was confirmed by Fourier transformed infrared (FT-IR) spectrum. High-resolution transmission electron microscopy (HR-TEM) and high-resolution scanning electron microscopy (HR-SEM) were used to investigate the morphology of the synthesized sample. These images showed the sphere-like morphology. The elemental composition of the sample was determined by the energy dispersive X-ray analysis (EDX). Selected area electron diffraction (SAED) was used to find the crystalline nature of the Ag NPs. The electrochemical behavior of the synthesized Ag NPs was analyzed by the cyclic voltammetry (CV). Antibacterial experiments showed that the prepared Ag NPs showed relatively similar antibacterial activities, when compared with AgNO{sub 3} against Gram-positive and Gram-negative bacteria. - Highlights: • Microwave irradiation method is used to synthesize silver nanoparticles. • Highly stable silver nanoparticles are produced from serine. • A detailed study of antibacterial activities is discussed. • Formation mechanism of silver microspheres has been proposed.

  10. Irradiation study of PNNL synthesized glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Kossoy-simakov, Anna-eden [Los Alamos National Laboratory; Tang, Ming [Los Alamos National Laboratory; Valdez, James A [Los Alamos National Laboratory; Usov, Igor O [Los Alamos National Laboratory; Sickafus, Kurt E [Los Alamos National Laboratory

    2011-01-18

    Two types of glass-ceramic were investigated: (1) for immobilization of Ln, alkali, and alkaline earths (GC4); and (2) same as above + high (7%) molybdenum content (Mo7) multiphase specimens. The purpose was to study the radiation stability of PNNL synthesized glass-ceramics and changes in microstructure/phase composition.

  11. Synthesizing the Effect of Building Condition Quality on Academic Performance

    Science.gov (United States)

    Gunter, Tracey; Shao, Jing

    2016-01-01

    Since the late 1970s, researchers have examined the relationship between school building condition and student performance. Though many literature reviews have claimed that a relationship exists, no meta-analysis has quantitatively examined this literature. The purpose of this review was to synthesize the existing literature on the relationship…

  12. CEO-Phase Stabilized Few-Cycle Field Synthesizer

    Science.gov (United States)

    Rausch, Stefan; Binhammer, Thomas; Harth, Anne; Kärtner, Franz X.; Morgner, Uwe

    We present an optical field synthesizer consisting of a CEO-phase stabilized octavespanning Ti:sapphire laser oscillator and prism-based pulse shaper allowing for full control of the electric field on a sub-femtosecond time-scale.

  13. A Model of Educational Leadership: Wisdom, Intelligence, and Creativity, Synthesized

    Science.gov (United States)

    Sternberg, Robert J.

    2005-01-01

    This article presents a model of educational leadership--WICS--that encompasses "wisdom", "intelligence" and "creativity", "synthesized". The article opens with a general discussion of issues in models of leadership. Then it discusses the role of creativity in leadership, dividing the discussion into academic and practical aspects. Next it deals…

  14. Some Remarks on Asymmetric Syntheses from Recent Studies

    OpenAIRE

    Baba, Naomichi

    1990-01-01

    Some asymmetric syntheses were presented here and discussed briefly including NADH model reactions, phase transfer-catalyzed asymmetric epoxidation, enantiotopic group-selective hydrolysis of a malonic anhydride with alkoxide anion, intramolecular acid-catalyzed lactonizations, catalytic asymmetric Diels-Alder synthesis, asymmetric aldol condensation, chiral homoallyl alcohol synthesis, asymmetric addition of diethylzinc to aldehyde, kinetic resolution of racemic hydroperoxides and binaphthol...

  15. A frequency tracking synthesizer for beam diagnostic systems

    International Nuclear Information System (INIS)

    In low and medium energy synchrotrons the beam revolution frequency changes by a large factor during the acceleration process. High production rates require that these machines cycle rapidly. In attempting to diagnose instabilities which develop during the acceleration process it is useful to be able to select some frequency segment between revolution harmonics for viewing. Most types of test equipment operating in the frequency domain, such as spectrum analyzers and network analyzers, are not suited to making direct measurements on such rapidly sweeping signals. Ideally, one would want to set the frequency frame of reference to the spot in the accelerating revolution harmonic domain where the measurements are to be made. A scheme using a direct digital synthesizer (DDS) was developed to provide this moving reference frame. This paper describes a synthesizer scheme combining digital and analog synthesizer techniques to allow tracking of signals during acceleration. Virtually any ratio of synthesizer to beam revolution frequency may be generated by this scheme. Details of hardware and measurement results are presented

  16. Method for synthesizing peptides with saccharide linked enzyme polymer conjugates

    Science.gov (United States)

    Callstrom, M.R.; Bednarski, M.D.; Gruber, P.R.

    1997-06-17

    A method is disclosed for synthesizing peptides using water soluble enzyme polymer conjugates. The method comprises catalyzing the peptide synthesis with enzyme which has been covalently bonded to a polymer through at least three linkers which linkers have three or more hydroxyl groups. The enzyme is conjugated at lysines or arginines. 19 figs.

  17. Design und Synthese maßgeschneiderter funktioneller Rylenfarbstoffe

    OpenAIRE

    Schnitzler, T.

    2011-01-01

    Die vorgelegte Dissertation beschäftigt sich mit der Darstellung und Untersuchung von funktionellen Farbstoffen auf der Basis von Rylendiimiden. Diese Substanzklasse zeichnet sich durch gute Funktionalisierbarkeit, hohe chemische und photochemische Stabilität sowie durch hohe Fluoreszenzquantenausbeuten und Extinktionskoeffizienten aus. Rylendiimide spielen eine bedeutsame Rolle in den modernen Materialwissenschaften. Ein Schwerpunkt der Arbeit liegt auf der Synthese und Untersuchung von neue...

  18. Radiolitically Synthesized Hybrid Nanosystems for Bio-Nano-Technologies

    International Nuclear Information System (INIS)

    In this report a review of the main results and the studies carried out under the scope of the IAEA CRP project: Nanoscale Radiation Engineering of Advanced Materials for Potential Biomedical Application is presented. In particular two topics are discussed: radiation synthesizing of Ag nanoparticles in hydrogels for potential biomedical application and decoration of carbon nanotubes with Ag clusters by gamma irradiation. (author)

  19. Branched nanostructures and method of synthesizing the same

    Science.gov (United States)

    Fonseca, Luis F. (Inventor); Resto, Oscar (Inventor); Sola, Francisco (Inventor)

    2009-01-01

    A branched nanostructure is synthesized. A porous material, with pores having a diameter of approximately 1 .mu.m or less, is placed in a vacuum. It is irradiated with an electron beam. This causes a trunk to grow from the porous material and further causes branches to grow from the trunk.

  20. Syntheses of Some Organic Fluorescent Dyes for Security Tickers

    Institute of Scientific and Technical Information of China (English)

    LI Jun-fen; BAI Guan; LIN Pei-hua; TIAN Mei-lin; DONG Chuan; LI Du-xin

    2004-01-01

    Five organic fluorescence dyes were synthesized by two- or three-step reactions. These synthetic methods have an advantage of the simple processes, low costs and high yields. The compositions of the five compounds are characterized by IR, 1H NMR, elemental analyses and fluorescence spectroscopies. The quantum yields of fluorescence were measured.

  1. Indenyl-Ruthenium-Thioaldehyd-Komplexe : Synthese, Struktur und Additionsreaktionen

    OpenAIRE

    Fischer, Frank

    2006-01-01

    Neue Indenyl-Ruthenium-Thioaldehyd-Komplexe wurden in einer fünfstufigen Synthese ausgehend von Ruthenium-(III)-chlorid erhalten. Die Thioaldehyd-Komplexe und alle Zwischenprodukte wurden NMR-spektroskopisch sowie kristallographisch untersucht und charakterisiert. Die neuartigen Verbindungen wurden auf ihre Reaktivität in Hetero-Diels-Alder-Reaktionen und nucleophilen Additionen hin untersucht.

  2. ARSENIC REMOVAL USING SOL-GEL SYNTHESIZED TITANIUM DIOXIDE NANOPARTICLES

    Science.gov (United States)

    In this study, the effectiveness of TiO2 nanoparticles in arsenic adsorption was examined. TiO2 particles (LS) were synthesized via sol-gel techniques and characterized for their crystallinity, surface area and pore volume. Batch adsorption studies were perf...

  3. Synthesizing a Life: An Interview with Carl Djerassi

    Science.gov (United States)

    Cardellini, Liberato

    2011-01-01

    In this interview, Carl Djerassi recalls his first years, from his pleasant childhood, to how he escaped the Nazi persecutions, to his college education in America. He remembers how with his research group he won the race for synthesis of cortisone, and how they then synthesized norethindrone, the active ingredient in oral contraceptives. Djerassi…

  4. Plasma-Liquid Interaction: a New Way to Synthesize Nanomaterials

    CERN Document Server

    Chen, Qiang; Li, Yongfeng; Zhang, Xianhui; Yang, Size

    2014-01-01

    In this review, we have summarized the recent advances and present conditions of the nanomaterials synthesis from the plasma-liquid interactions. A theoretical analysis for the nanomaterials synthesis process is presented by analyzing the experimental data. Besides the theoretical analysis, the practical applications in several nanomaterials syntheses of the the plasma-liquid interactions are also presented.

  5. A practical chemo-enzymatic approach to highly enantio-enriched 10-ethyl-7,8-dihydro-γ-ionone isomers: a method for the synthesis of 4,5-didehydro-α-ionone.

    Science.gov (United States)

    Barakat, Assem; Al-Majid, Abdullah M; Mabkhot, Yahia Nasser; Al-Othman, Zeid Abdullah

    2012-01-01

    An efficient and convenient strategy for the enantioselective synthesis of enantiomerically enriched 10-ethyl-7,8-dihydro-γ-ionone isomers (R)-(+)-7, and (S)-(-)-7 are described utilizing a lipase mediated resolution protocol, and reductive elimination of the secondary allylic alcohol as the key step. The enantioselective and diastereoselective lipase kinetic acetylation of 4-hydroxy-γ-ionone derivatives 6a afforded the 4-acetyl-γ-ionone derivatives (-)-8, and the 4-hydrox-γ-ionone derivatives (+)-6a, which are suitable precursors of the desired products. Stereospecific palladium-mediated elimination of allylic acetate provides the target compounds with an excellent enantiomeric excess and yield. Additionally, the novel 4,5-didehydro-α-ionone 13 is obtained from readily prepared (2,6,6-trimethylcyclohexa-2,4-dien-1-yl) methanol 9. The structures of all newly synthesized compounds have been elucidated by (1)H, (13)C NMR, GC-MS, and IR spectrometry. These compounds represent a new class of odorants that may be of pivotal relevance in industrial perfumery. PMID:22754314

  6. A Practical Chemo-enzymatic Approach to Highly Enantio-Enriched 10-Ethyl-7,8-dihydro-γ-ionone Isomers: A Method for the Synthesis of 4,5-Didehydro-α-Ionone

    Directory of Open Access Journals (Sweden)

    Zeid Abdullah Al-Othman

    2012-05-01

    Full Text Available An efficient and convenient strategy for the enantioselective synthesis of enantiomerically enriched 10-ethyl-7,8-dihydro-γ-ionone isomers (R-(+-7, and (S-(−-7 are described utilizing a lipase mediated resolution protocol, and reductive elimination of the secondary allylic alcohol as the key step. The enantioselective and diastereoselective lipase kinetic acetylation of 4-hydroxy-γ-ionone derivatives 6a afforded the 4-acetyl-γ-ionone derivatives (−-8, and the 4-hydrox-γ-ionone derivatives (+-6a, which are suitable precursors of the desired products. Stereospecific palladium-mediated elimination of allylic acetate provides the target compounds with an excellent enantiomeric excess and yield. Additionally, the novel 4,5-didehydro-α-ionone 13 is obtained from readily prepared (2,6,6-trimethylcyclohexa-2,4-dien-1-yl methanol 9. The structures of all newly synthesized compounds have been elucidated by 1H, 13C NMR, GC-MS, and IR spectrometry. These compounds represent a new class of odorants that may be of pivotal relevance in industrial perfumery.

  7. Interaction Studies between Newly Synthesized Photosensitive Polymer and Ionic Liquids

    Directory of Open Access Journals (Sweden)

    In Tae Kim

    2015-01-01

    Full Text Available In this information age, different kinds of photosensitive materials have been used in the manufacture of information storage devices. But these photosensitive materials have the bane of low diffraction efficiency. In order to solve this problem, we have synthesized a novel photosensitive polymer from epoxy-based azopolymers (with three types of azochromophores. Furthermore, we have studied the interaction between this newly synthesized azopolymer and ionic liquids (ILs. For this purpose, we have used the ammonium and imidazolium families of ILs, such as diethylammonium dihydrogen phosphate (DEAP, tributylammonium methyl sulfate (TBMS, triethylammonium 4-aminotoluene-3-sulfonic acid (TASA, and 1-methylimidazolium chloride ([Mim]Cl. To investigate the molecular interaction between azopolymer and ILs, we have used the following spectroscopic methods of analysis: UV-visible spectroscopy, photoluminescence (PL spectroscopy, Fourier transformed infrared spectroscopy (FT-IR, and confocal Raman spectroscopy. In this study, we have developed new photosensitive materials by combining polymer with ILs.

  8. Fatty acid composition of oil synthesized by Aspergillus nidulans.

    Science.gov (United States)

    Sharma, N D; Mathur, J M; Saxena, B S; Sen, K

    1981-01-01

    The filamentous fungus Aspergillus nidulans Eidam strain 300 was found to be capable of synthesizing 24.9% oil or remarkably low free fatty acidity, in a chemically defined medium with 34% glucose as sole carbon source. although the total content of oil synthesized was less, utilization of the carbon source is better as shown by the high (8.4) fat coefficient. The major component fatty acids of the oil were palmitic, stearic, oleic and linoleic and are influenced by the source of carbon. Palmitoleic acid is present in traces, confirming thereby the general observation that high oil formers produce oil of low hexadecenoic acid content. The relatively high stearic acid content of the oil distinguishes it from those of other microorganisms and resembles the oil produced by certain tropical plants, such as Madhuca latifolia. PMID:7026394

  9. Antibacterial and catalytic activities of green synthesized silver nanoparticles

    Science.gov (United States)

    Bindhu, M. R.; Umadevi, M.

    2015-01-01

    The aqueous beetroot extract was used as reducing agent for silver nanoparticles synthesis. The synthesized nanoparticles were characterized using UV-visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The surface plasmon resonance peak of synthesized nanoparticles was observed at 438 nm. As the concentration of beetroot extract increases, absorption spectra shows blue shift with decreasing particle size. The prepared silver nanoparticles were well dispersed, spherical in shape with the average particle size of 15 nm. The prepared silver nanoparticles are effective in inhibiting the growth of both gram positive and gram negative bacteria. The prepared silver nanoparticles reveal faster catalytic activity. This natural method for synthesis of silver nanoparticles offers a valuable contribution in the area of green synthesis and nanotechnology avoiding the presence of hazardous and toxic solvents and waste.

  10. Method of synthesizing silica nanofibers using sound waves

    Science.gov (United States)

    Sharma, Jaswinder K.; Datskos, Panos G.

    2015-09-15

    A method for synthesizing silica nanofibers using sound waves is provided. The method includes providing a solution of polyvinyl pyrrolidone, adding sodium citrate and ammonium hydroxide to form a first mixture, adding a silica-based compound to the solution to form a second mixture, and sonicating the second mixture to synthesize a plurality of silica nanofibers having an average cross-sectional diameter of less than 70 nm and having a length on the order of at least several hundred microns. The method can be performed without heating or electrospinning, and instead includes less energy intensive strategies that can be scaled up to an industrial scale. The resulting nanofibers can achieve a decreased mean diameter over conventional fibers. The decreased diameter generally increases the tensile strength of the silica nanofibers, as defects and contaminations decrease with the decreasing diameter.

  11. Doped semiconductor nanoparticles synthesized in gas-phase plasmas

    International Nuclear Information System (INIS)

    Crystalline nanoparticles (NPs) of semiconductor materials have been attracting huge research interest due to their potential use in future applications like photovoltaics and bioimaging. The important role that intentional impurity doping plays in semiconductor technology has ignited a great deal of research effort aiming at synthesizing semiconductor NPs doped with foreign impurities and at understanding their physical and chemical properties. In this respect, plasma-grown semiconductor NPs doped in situ during synthesis have been key in studies of doped NPs. This article presents a review of the advances in understanding the properties of doped semiconductor NPs synthesized by means of plasma methods and the role played by these NPs for our current understanding of doped NPs and the general behavior of doping in nanoscale materials. (review article)

  12. Cerium uptake by zeolite A synthesized from natural clinoptilolite tuffs

    International Nuclear Information System (INIS)

    Natural clinoptilolite tuffs from the Semnan region in Iran was used for the synthesis of zeolite A. The tuffs and synthesized zeolites were characterized by XRD and XRF. The sorption behavior of the synthesized zeolite toward cerium was studied. Using the Lagergren's equation, the absorption constant was calculated. The measured distribution coefficient values (Kd) indicated that cerium uptake is higher in lower initial concentrations, higher temperature and higher pH values. Thermodynamic parameters of the exchange were calculated through construction of ion-exchange isotherms at three temperatures of 298, 323 and 343 K. The dynamic absorption of cerium was also studied by passing the solution through a column in the presence and absence of sodium ions. (author)

  13. Properties of zeolite a synthesized by natural bentonite

    International Nuclear Information System (INIS)

    Synthetic zeolite was prepared by using of natural bentonite from Kampo area and the application of detergent builder was investigated. The optimum synthetic condition was SiO2/Al2O3 = 2, Na2O/Al2O3 = 1, H2O/Al2O3 30 at 90 deg C for 3 hr and it was found by XRD analysis that the zeolite synthesized under this condition was type A. When the zeolite A synthesized under the optimum condition was contacted with 40 deg Dh CaCl2 solution at 30 deg C for 15 min, the cation exchange capacity was 264.9 mg CaO/g-zeolite. And the whiteness of the sample was 89% and the mean particle size was 9.95μm. (author)

  14. Design of optocoupler for synthesizing four color spectra

    Science.gov (United States)

    Liu, Zechun; Ge, Aiming; Tao, Xinran; Yang, Shengqi; Wang, Tianyi

    2016-07-01

    LEDs with the advantage of high luminous efficacy and long life time show the potential of replacing traditional luminaire. Most commercial white LED light sources use blue or ultraviolet chip coated with emitting phosphor, but the sensitivity and instability of such phosphors has become a big issue. The typical RGB-LED by using individual chips has the problem of spatial separation and insufficient spectral overlap which leads to low CRI. This study suggests a novel and high-efficiency design of fiber optical optocoupler to synthesize four colors emitted by separate LEDs to provide the ideal light sources by adjusting the individual LEDs separately. By choosing different colored light to be synthesized, this optocoupler can be used as light sources which can be highly controlled to offer the best lighting conditions. Compared with other widely used commercial LED sources, this new design of light sources can be used in special experiments which require multi-spectral light.

  15. Is Synthesizing MRI Contrast Useful for Inter-modality Analysis?

    DEFF Research Database (Denmark)

    Iglesias, Juan Eugenio; Konukoglu, Ender; Zikic, Darko;

    2013-01-01

    Availability of multi-modal magnetic resonance imaging (MRI) databases opens up the opportunity to synthesize different MRI contrasts without actually acquiring the images. In theory such synthetic images have the potential to reduce the amount of acquisitions to perform certain analyses. However......, to what extent they can substitute real acquisitions in the respective analyses is an open question. In this study, we used a synthesis method based on patch matching to test whether synthetic images can be useful in segmentation and inter-modality cross-subject registration of brain MRI. Thirty......-nine T1 scans with 36 manually labeled structures of interest were used in the registration and segmentation of eight proton density (PD) scans, for which ground truth T1 data were also available. The results show that synthesized T1 contrast can considerably enhance the quality of non...

  16. Kinetics of Enzyme Biodegradation of New Synthesized Copolymers

    Directory of Open Access Journals (Sweden)

    Rosa Mateva

    2005-04-01

    Full Text Available Block copolymers of the poly-(hexanlactam-co-block-poly-(?-valerolactone from ABA-type were synthesized via anionic polymerization of hexanlactam (HL with the sodium salt of hexanlactam (Na-HL as an initiator and polymeric activator (PAC. PAC, on the base of poly-?-valerolactone (PVL, was used as a soft central block. Synthetic PVL is very attractive biomaterial - nontoxic, biocompatibility and biodegradable polyester[5-8]. Modification of HL with PVL, renders these system biodegradable[1]. Isolated copolymers were characterized by various spectroscopic techniques. The effect of the chemical and physical structure of the synthesized block copolymers on the biodegradation was investigated. Biodegradation of block copolyester amides was studied by means of lipase and involves the enzymatic hydrolysis of ester groups in PVL.

  17. Syntheses of amidoxime polyethylene resin for selective Uranium (VI) adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Seung; Lee, Soo Yeon; Kim, Sang Hoon [Korea University, Seoul (Korea, Republic of)

    2010-05-15

    Uranium is a major element in the management of spent nuclear fuel (SF) or radioactive wastes, and selective separation of U has been one of research targets. For the separation of U from fission products (FP) in a SF, usually, a solvent extraction or an ion exchange technology has been usually used in an acid medium. In the case of ion exchange method, anion exchanger has been used. However, recently, some absorbents containing amidoxime functional group selective for the U have been designed and synthesized. Therefore, new adsorbent capable of selective sensing U over FP in a carbonate solution are now highly demanded. So, in this study, total synthesis of the polymer-amidoxime derivatives, divinylbenzene-amidoxime (DVB-AO) and polyethylene amidoxime (PE-AO) have been developed and the desired final products were successfully synthesized

  18. Syntheses of amidoxime polyethylene resin for selective Uranium (VI) adsorption

    International Nuclear Information System (INIS)

    Uranium is a major element in the management of spent nuclear fuel (SF) or radioactive wastes, and selective separation of U has been one of research targets. For the separation of U from fission products (FP) in a SF, usually, a solvent extraction or an ion exchange technology has been usually used in an acid medium. In the case of ion exchange method, anion exchanger has been used. However, recently, some absorbents containing amidoxime functional group selective for the U have been designed and synthesized. Therefore, new adsorbent capable of selective sensing U over FP in a carbonate solution are now highly demanded. So, in this study, total synthesis of the polymer-amidoxime derivatives, divinylbenzene-amidoxime (DVB-AO) and polyethylene amidoxime (PE-AO) have been developed and the desired final products were successfully synthesized

  19. Practical enantiospecific syntheses of lysobisphosphatidic acid and its analogues.

    Science.gov (United States)

    Jiang, Guowei; Xu, Yong; Prestwich, Glenn D

    2006-02-01

    We describe a versatile, efficient, and practical method for the preparation of enantiomerically pure lysobisphosphatidic acid (LBPA), bisether analogues, and phosphorothioate analogues of LBPA from solketal. Phosphorylation of a protected sn-2-O-oleoyl glycerol with 2-cyanoethyl bis(N,N-diisopropylamino)phosphite, followed by oxidation and deprotection, generated the enantiomers of 2,2'-LBPA. The corresponding phosphorothioate analogues were obtained by oxidation with sulfur. The (R,R) and (S,S) enantiomers of both LBPA and phosphorothioate LBPA were synthesized from (S)- and (R)-solketal, respectively. The ether analogue of (S,S)-lysobisphosphatidic acid (LBPA) and its enantiomer were synthesized from the same enantiomer (S)-solketal by simply changing the sequence of deprotection steps. PMID:16438504

  20. Bis(indolyl)methane alkaloids: Isolation, bioactivity, and syntheses

    Digital Repository Service at National Institute of Oceanography (India)

    Praveen, P.; Parameswaran, P.S.; Majik, M.S.

    Author version: Synthesis - Stuttgart, vol.47; 2015; 1827-1837 Bisindolyl Methane Alkaloids: Isolation, Bioactivity and Syntheses P. J. Praveen,a,b P. S. Parameswaran*b, M. S. Majik*c aCSIR-National Institute of Oceanography, Bioorganic Chemistry... Laboratory, Dona Paula Goa- India; bCSIR-National Institute of Oceanography Regional centre, Kochi, India, Email:param@nio.org; cDepartment of Chemistry, Goa University, Goa 403 206, India, Email:majikms@gmail.com Abstract Bis...

  1. EPR Beams and Photon Number Detector: Toward Synthesizing Optical Nonlinearity

    OpenAIRE

    Sasaki, M; Wakui, K.; Mizuno, J.; Fujiwara, M.; Akiba, M

    2006-01-01

    We present the two kinds of experimental results. One is a continuous variable dense coding experiment, and the other is a photon number detector with high linearity response, the so called charge integration photon detector (CIPD). They can be combined together to be a potential tool for implementing the cubic phase gate which is an important gate element to synthesize the measurement induced nonlinearity for photonic quantum information processing.

  2. A novel way to synthesize Pb nanotapes in liquid ammonia

    Institute of Scientific and Technical Information of China (English)

    Lei Sun; Meng Lei Zhang; Xiao Jun Tao; Yan Bao Zhao

    2011-01-01

    Lead nanotapes were synthesized in liquid ammonia solvent in the presence of sodium metal at low temperature. The process was template free. Transmission electron microscopy (TEM) observations and X-ray diffraction (XRD) characterizations revealed that the as-prepared Pb nanotapes have average diameters in the range of 40-50 nm, and lengths up to several hundred nanometers, and exhibit cubic crystal structures.

  3. Applications of Magnetosomes Synthesized by Magnetotactic Bacteria in Medicine

    OpenAIRE

    EdouardAlphandéry

    2014-01-01

    Magnetotactic bacteria belong to a group of bacteria that synthesize iron oxide nanoparticles covered by biological material that are called magnetosomes. These bacteria use the magnetosomes as a compass to navigate in the direction of the earth’s magnetic field. This compass helps the bacteria to find the optimum conditions for their growth and survival. Here, we review several medical applications of magnetotactic bacteria and magnetosomes, such as those in magnetic resonance imaging (MRI),...

  4. Monodispersive CoPt Nanoparticles Synthesized Using Chemical Reduction Method

    Institute of Scientific and Technical Information of China (English)

    SHEN Cheng-Min; HUI Chao; YANG Tian-Zhong; XIAO Cong-Wen; CHEN Shu-Tang; DING Hao; GAO Hong-Jun

    2008-01-01

    @@ Monodispersive CoPt nanoparticles in sizes of about 2.2 nm are synthesized by superhydride reduction of CoCl2 and PtCl2 in diphenyl ether. The as-prepared nanoparticles show a chemically disordered A1 structure and are superparamagnetic. Thermal annealing transforms the A1 structure into chemically ordered L1o structure and the particles are ferromagnetic at room temperature.

  5. Chemie metastabiler Anionen : Synthese und Charakterisierung neuer Auride und Ozonide

    OpenAIRE

    Nuß, Hannelore

    2007-01-01

    Die vorliegende Arbeit beschreibt die Synthese und Charakterisierung neuer Ozonid- und Auridverbindungen, sowie Verbindungen des Quadratatdianions. Fünf neue Ozonidverbindungen wurden ausgehend von den Alkalimetallozoniden KO_3, RbO_3 und CsO_3 durch Umsetzung mit verschiedenen Kronenetherliganden in flüssigem Ammoniak hergestellt. Das Verhältnis zwischen Ligandendurchmesser und Kationenradius bestimmt dabei die Art der Komplexierung des Metallzentrums und damit auch die Packung der Kompl...

  6. Transport properties of chemically synthesized polypyrrole thin films

    OpenAIRE

    Bufon, C. C. Bof; Heinzel, T.

    2007-01-01

    The electronic transport in polypyrrole thin films synthesized chemically from the vapor phase is studied as a function of temperature as well as of electric and magnetic fields. We find distinct differences in comparison to the behavior of both polypyrrole films prepared by electrochemical growth as well as of the bulk films obtained from conventional chemical synthesis. For small electric fields F, a transition from Efros-Shklovskii variable range hopping to Arrhenius activated transport is...

  7. A green chemistry approach for synthesizing biocompatible gold nanoparticles

    OpenAIRE

    Gurunathan, Sangiliyandi; Han, JaeWoong; Park, Jung Hyun; Kim, Jin-Hoi

    2014-01-01

    Gold nanoparticles (AuNPs) are a fascinating class of nanomaterial that can be used for a wide range of biomedical applications, including bio-imaging, lateral flow assays, environmental detection and purification, data storage, drug delivery, biomarkers, catalysis, chemical sensors, and DNA detection. Biological synthesis of nanoparticles appears to be simple, cost-effective, non-toxic, and easy to use for controlling size, shape, and stability, which is unlike the chemically synthesized nan...

  8. Synthesizing Sierpinski Antenna by Genetic Algorithm and Swarm Optimization

    OpenAIRE

    Z. Raida; Vidal, B. M.

    2008-01-01

    The paper discusses the synthesis of the Sierpinski antenna operating at three prescribed frequencies: 0.9 GHz, 1.8 GHz (both GSM) and 2.4 GHz (Bluetooth). In order to synthesize the antenna, a genetic algorithm and a particle swarm optimization were used. The numerical model of the antenna was developed in Zeland IE3D, optimization scripts were programmed in MATLAB. Results of both the optimization methods are compared and experimentally verified.

  9. Mesoporous zeolite and zeotype single crystals synthesized in fluoride media

    DEFF Research Database (Denmark)

    Egeblad, Kresten; Kustova, Marina; Klitgaard, Søren Kegnæs;

    2007-01-01

    materials were all prepared by hydrothermal crystallization of gels adsorbed on carbon matrices which were subsequently removed by combustion. The procedures presented here resulted in mesoporous zeolite and zeotypes materials with MFI, MEL, BEA, AFI and CHA framework structures. All samples were...... opposed to mesoporous single crystals. For the zeotype materials it was found that highly crystalline mesoporous materials of AFI and CHA structure types could be synthesized using a newly developed procedure. (c) 2006 Elsevier Inc. All rights reserved....

  10. Bioinspired Collective Syntheses of Iboga-Type Indole Alkaloids.

    Science.gov (United States)

    Zhao, Gaoyuan; Xie, Xingang; Sun, Haiyu; Yuan, Ziyun; Zhong, Zhuliang; Tang, Shouchu; She, Xuegong

    2016-05-20

    We present the application of a bioinspired collective synthesis strategy in the total syntheses of seven iboga-type indole alkaloids: (±)-tabertinggine, (±)-ibogamine, (±)-ibogaine, (±)-ibogaine hydroxyindolenine, (±)-3-oxoibogaine hydroxyindolenine, (±)-iboluteine, and (±)-ervaoffines D. In particular, tabertinggine and its congeners serve as iboga precursors for the subsequent biomimetic transformations into other iboga-type alkaloids. PMID:27160167

  11. New synthesizing feature parameter of wear particles image

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper outlines the application of wavelet analysis method to computering wear par-ticles image processing and introduces the concept of grain parameter for wear particle imagebased on statistical feature parameters. The feature of wear particles image can be obtained fromthe wavelet decomposition and the statistics analysis. Test results showed that grain parametercan be used as a synthesizing feature parameter for wear particle image.

  12. Economical parallel oligonucleotide and peptide synthesizer - PET OLIGATOR

    Czech Academy of Sciences Publication Activity Database

    Lebl, M.; Pistek, Ch.; Hachmann, J.; Mudra, Petr; Pešek, Václav; Pokorný, Vít; Poncar, Pavel; Ženíšek, Karel

    2007-01-01

    Roč. 13, 1/2 (2007), s. 367-375. ISSN 1573-3149 Grant ostatní: NIH SBIR(US) R43 GM61511-01; NIH SBIR(US) R43 GM58981-01 Institutional research plan: CEZ:AV0Z40550506 Keywords : automated synthesizer * centrifugation * parallel synthesis Subject RIV: CC - Organic Chemistry Impact factor: 0.971, year: 2007

  13. Dendritische Polythioetherliganden zur Synthese von Goldnanopartikel-Oligonucleotid-Monokonjugaten

    OpenAIRE

    Mönninghoff, Sven

    2009-01-01

    Basierend auf der Entwicklung des Rubigoldes als thermostabilem Marker für Biomoleküle wurden in dieser Arbeit Polythioether-Liganden zur Synthese von monofunktionalen Cluster-Oligonucleotid-Konjugaten (COK) entwickelt. Zum Aufbau der Liganden wurden 2,4,6-substituierte Phenole als zentrales Strukturmotiv eingesetzt. Durch Konjugation der Ligandensysteme an Oligonucleotide wurden Ligand-Oligonucleotid-Konjugate (LOK) hergestellt, die durch Reduktion von Au (III)-Ionen in Anwesenhe...

  14. Annual reports in inorganic and general syntheses 1973

    CERN Document Server

    Niedenzu, Kurt

    1974-01-01

    Annual Reports in Inorganic and General Syntheses-1973 presents an organized annual summary of synthetic developments in inorganic chemistry and its related areas. The book covers the synthetic aspects and structural or mechanistic features of elements, including the main group hydrides, alkali and alkaline earth elements, boron, aluminium, gallium, indium, thallium, silicon, germanium, tin, and lead, nitrogen, phosphorus, arsenic, antimony, bismuth, chalcogens, halogens and pseudohalogens, and noble gases. The text also discusses the synthetic aspects and structural or mechanistic features of

  15. Core-modified octaphyrins: Syntheses and anion-binding properties

    Indian Academy of Sciences (India)

    Rajneesh Misra; Venkataramanarao G Anand; Harapriya Rath; Tavarekere K Chandrashekar

    2005-03-01

    In this paper, a brief review of the syntheses, characterization and anion-binding properties of core-modified octaphyrins is presented. It has been shown that the core-modified octaphyrins exhibit aromaticity both in solution and in solid state, confirming the validity of the (4 + 2) Huckel rule for larger -electron systems. Solid-state binding characteristics of TFA anions of two core-modified octaphyrins are also described.

  16. Annual reports in inorganic and general syntheses 1974

    CERN Document Server

    Niedenzu, Kurt

    1975-01-01

    Annual Reports in Inorganic and General Syntheses-1974 presents an organized annual summary of synthetic developments in inorganic chemistry and its related areas. The book discusses the chemistry of simple and complex metal hydrides of main groups I, II, and III, boron, aluminium, gallium, indium, thallium, silicon, germanium, tin, lead, phosphorus, arsenic, antimony, bismuth, chalcogens, halogens, and pseudohalogens. The text also describes the chemistry of scandium, yttrium, lanthanides, actinides, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, ma

  17. Blue Luminescence of CdS Nanowires Synthesized by Sulfurization

    Institute of Scientific and Technical Information of China (English)

    GAO Tao; MENG Guo-Wen; WANG Tai-Hong

    2004-01-01

    @@ Polycrystalline CdS nanowires have been synthesized by sulfurizing metal Cd nanowires deposited electrochemically within the nanochannels of porous anodic alumina (PAA) templates. Photoluminescence (PL) investigation shows that the CdS nanowires have an intensive and broad PL emission band peaked around 435nm. The investigation results suggest that localized defects and excess S atoms existing in the CdS nanowires are responsible for this blue luminescence.

  18. Kinetics of Enzyme Biodegradation of New Synthesized Copolymers

    OpenAIRE

    Rosa Mateva; Natalia Toncheva; Lubov Yotova

    2005-01-01

    Block copolymers of the poly-(hexanlactam)-co-block-poly-(?-valerolactone) from ABA-type were synthesized via anionic polymerization of hexanlactam (HL) with the sodium salt of hexanlactam (Na-HL) as an initiator and polymeric activator (PAC). PAC, on the base of poly-?-valerolactone (PVL), was used as a soft central block. Synthetic PVL is very attractive biomaterial - nontoxic, biocompatibility and biodegradable polyester[5-8]. Modification of HL with PVL, renders these system biodegradable...

  19. Annual reports in inorganic and general syntheses 1972

    CERN Document Server

    Niedenzu, Kurt

    1973-01-01

    Annual Reports in Inorganic and General Syntheses-1972 presents an organized annual summary of synthetic developments in inorganic chemistry and its related areas. The book discusses alkali and alkaline earth elements, alloys, silver, gold, zinc, cadmium, mercury, boron, aluminum, gallium, indium, thallium, yttrium, scandium, lanthanides, actinides, titanium, zirconium, hafnium, Group V and VI transition elements, manganese, technetium, rhenium, iron, cobalt, nickel, ruthenium, osmium, rhodium, and iridium. The text also describes the chemistry of palladium, platinum, silicon, germanium, tin,

  20. A Novel Synthesizing Genetic Logic Circuit: Frequency Multiplier.

    Science.gov (United States)

    Chuang, Chia-Hua; Lin, Chun-Liang

    2014-01-01

    This paper presents a novel synthesizing genetic logic circuit design based on an existing synthetic genetic oscillator, which provides a function of frequency multiplier to synthesize a clock signal whose frequency is a multiple of that of the genetic oscillator. In the renowned literature, the synthetic genetic oscillator, known as a repressilator, has been successfully built in Escherichia coli to generate a periodic oscillating phenomenon through three repressive genes repress each other in a chain. On the basis of this fact, our proposed genetic frequency multiplier circuit utilizes genetic Buffers in series with a waveform-shaping circuit to reshape the genetic oscillation signal into a crisp logic clock signal. By regulating different threshold levels in the Buffer, the time length of logic high/low levels in a fundamental sinusoidal wave can be engineered to pulse-width-modulated (PWM) signals with various duty cycles. Integrating some of genetic logic XOR gates and PWM signals from the output of the Buffers, a genetic frequency multiplier circuit can be created and the clock signal with the integer-fold of frequency of the genetic oscillator is generated. The synthesized signal can be used in triggering the downstream digital genetic logic circuits. Simulation results show the applicability of the proposed idea. PMID:26356341

  1. Synthesizing Behavioral Model of Event-Based Requirements

    Directory of Open Access Journals (Sweden)

    Seyyed M. Babamir

    2008-01-01

    Full Text Available Problem Statement: in the software engineering field, satisfaction of user's requirements by software has been a matter of concern. Therefore, monitoring software behavior against user's high-level requirements has already received a considerable and significant attention. However, the gap between low-level software behavior and high-level requirements has put an obstacle in the way of monitoring. Approach: to overcome the obstacle, we presented a method to synthesize a behavioral model of the event-based requirements in three steps: (1 eliciting event-based requirements; (2 specifying the requirements in event-based formulae and (3 mapping the formulae into a behavioral model. Results: to show effectiveness of the method, it was applied to requirements of a safety critical system, called Railroad Crossing Control (RCC one and a behavioral model was synthesized. The model was used to synthesize monitor of the RCC system. The monitor is responsible for surveillance of software behavior for preventing the collision between the train and some car at the junction of rail and road.Conclusions: we proposed a systematic method started from users' requirements elicitation and concluded with its behavioral specification. Focus of the method was on event-based real-time requirements which were stated by scenarios in a sequence of real-time interactions.

  2. A simple method for synthesizing and producing guitar sounds

    Science.gov (United States)

    Torres, Jesús A.; Rendón, Pablo L.

    2013-05-01

    An uncomplicated model is proposed to describe the transverse force exerted by a plucked string on a guitar bridge. This model incorporates the effect of internal damping, lending the synthesized sound a transient quality that makes it more realistic than sound produced without taking damping into account. The synthesized signals are then compared to actual measurements for both free and palm-muted vibrations, and show agreement in both cases. These synthesized signals can also be used to play MIDI files through a guitar acting as a modified loudspeaker cone, driving the instrument mechanically. The sound thus obtained is realistic and provides an interesting classroom exercise for an undergraduate audience. The main set-up is also affordable as a laboratory activity and for public demonstrations, and has the advantage of being simple to implement and flexible enough to allow different kinds of modification. It is, in fact, reliable enough to use as a tool for the comparison of different guitars driven in the same manner.

  3. Nanoformulation and antimicrobial evaluation of newly synthesized thiouracil derivatives.

    Science.gov (United States)

    Fadda, Ahmed A; Bayoumy, Nesma M; El-Sherbiny, Ibrahim M

    2016-07-01

    The present work reports the synthesis of a new series of pyridopyrimidine derivatives. The newly synthesized compounds were characterized by various analytical and spectral techniques. In addition, their antimicrobial activity was evaluated as well as modeling studies were performed to investigate their ability to recognize and bind to the biotin carboxylase (BC)-active site. The results showed a broad spectrum antibacterial and antifungal profile of the synthesized derivatives. Docking results demonstrated that all members of this class of new derivatives were able to recognize the active site of Escherichia coli BC and form different types of bonding interactions with key active site amino acid residues. Besides the compounds with promising antimicrobial activity in addition to 6-aminothiouracil, as control, were incorporated into polycaprolactone nanoparticles to improve their water solubility, permeability through physiological barriers and consequently enhanced therapeutic efficacy. The compounds-loaded nanoparticles were prepared using single emulsion-solvent evaporation technique, and their diameters were found to be in the range 136 ± 30 to 213 ± 28 nm. Transmission electron microscopy (TEM) showed a spherical and dense morphology of the nanoparticles. The results also showed high entrapment efficiency of the synthesized bioactive compounds in the nanoparticles (85 ± 5% to 91 ± 2%) with a desirable in vitro biodegradation and release profiles. PMID:26559404

  4. Design & Implementation of High Switching & Low Phase Noise Frequency Synthesizer

    Directory of Open Access Journals (Sweden)

    Ali M. N. Hassan

    2006-01-01

    Full Text Available This research describes the design & implementation of frequency synthesizer using single loop Phase lock loop with the following specifications: Frequency range (1.5 – 2.75 GHz,Step size (1 MHz, Switching time 36.4 µs, & phase noise @10 kHz = -92dBc & spurious -100 dBc The development in I.C. technology provide the simplicity in the design of frequency synthesizer because it implements the phase frequency detector(PFD , prescalar & reference divider in single chip. Therefore our system consists of a single chip contains (low phase noise PFD, charge pump, prescalar & reference divider, voltage controlled oscillator , loop filter & reference oscillator. The single chip is used to provide the following properties :•Low power consumptionSmall size, light weight.Flexibility in selecting crystal oscillator frequencies to fit into the system frequency planning.•High reliability.The application of this synthesizer in frequency hopping systems, satellite communications & radar because it has high switching speed ,low phase noise & low spurious level.

  5. Soft-Template-Synthesized Mesoporous Carbon for Oral Drug Delivery

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Dipendu [ORNL; Warren, Kaitlyn E [ORNL; Naskar, Amit K [ORNL

    2014-01-01

    Template-synthesized mesoporous carbons were successfully used in in vitro investigations of controlled delivery of three model drugs, captopril, furosemide, and ranitidine hydrochloride. Captopril and furosemide exhibited desorption kinetics over 30 40 h, and ranitidine HCl had a complete release time of 5 10 h. As evident from the slow release kinetics, we contend that our mesoporous carbon is an improved drug-delivery medium compared to state-of-the-art porous silica-based substrates. The mesoporous carbons, synthesized from phloroglucinol and lignin, a synthetic and a sustainable precursor, respectively, exhibit BET surface area of 200 400 m2 g-1 and pore volume of 0.2 0.6 cm3 g-1. The phloroglucinol-based carbon has narrower pore widths and higher pore volume than the lignin-derived counterpart and maintains a longer release time. Numerical modeling of the release kinetics data reveals that the diffusivities of all the drugs from lignin-based carbon media are of equivalent magnitude (10-22 to 10-24 m2 s-1). However, a tailored reduction of pore width in the sorbent reduces the diffusivity of smaller drug molecules (captopril) by an order of magnitude. Thus, engineered pore morphology in our synthesized carbon sorbent, along with its potential to tailor the chemistry of its interaction with sorbet, can be exploited for optimal delivery system of a preferred drug within its therapeutic level and below the level of toxicity.

  6. Bacteriocins synthesized by Bacillus thuringiensis: generalities and potential applications

    Science.gov (United States)

    Salazar-Marroquín, Elma Laura; Galán-Wong, Luis J.; Moreno-Medina, Víctor Ricardo; Reyes-López, Miguel Ángel; Pereyra-Alférez, Benito

    2016-01-01

    The members of the Bacillus thuringiensis group, commonly known as Bt, produce a huge number of metabolites, which show biocidal and antagonistic activity. B. thuringiensis is widely known for synthesizing Cry, Vip and Cyt proteins, active against insects and other parasporins with biocidal activity against certain types of cancerous cells. Nevertheless, B. thuringiensis also synthesizes compounds with antimicrobial activity, especially bacteriocins. Some B. thuringiensis bacteriocins resemble lantibiotics and other small linear peptides (class IIa) from the lactic acid bacteria bacteriocins classification system. Although many bacteriocins produced by Bt have been reported, there is no proper classification for them. In this work, we have grouped these based on molecular weight and functionality. Bacteriocins are small peptides synthesized by bacteria, presenting inhibitory activity against Gram-positive and Gram-negative bacteria and to a lesser extent against fungi. These molecules represent a good study model in the search for microbial control alternatives. Lactic acid bacteria produces a huge number of these types of molecules with great potential. Nonetheless, members of the Bacillus, cereus group, especially B. thuringiensis, emerge as an attractive alternative for obtaining bacteriocins showing novel activities. This review describes the potential applications of B. thuringiensis bacteriocins in the control of foodborne pathogens, environment and medical area. PMID:27340340

  7. Substitution of conventional high-temperature syntheses of inorganic compounds by near-room-temperature syntheses in ionic liquids

    KAUST Repository

    Groh, Matthias Friedrich

    2013-01-01

    The high-temperature syntheses of the low-valent halogenides P2I4, Te2Br, α-Te4I4, Te4(Al2Cl7)2, Te4(Bi6Cl20), Te8(Bi4Cl14),Bi8(AlCl4)2, Bi6Cl7,and Bi6Br7, as well as of WSCl4 andWOCl4 have been replaced by resource-efficient low-temperature syntheses in room temperature ionic liquids (RTILs). The simple one-pot syntheses generally do not require elaborate equipment such as twozone furnaces or evacuated silica ampoules. Compared to the published conventional approaches, reduction of reaction time (up to 80%) and temperature (up to 500 K) and, simultaneously, an increase in yield were achieved. In the majority of cases, the solid products were phase-pure. X-Ray diffraction on single crystals (redetermination of 11 crystal structures) has demonstrated that the quality of the crystals from RTILs is comparable to that of products obtained by chemical transport reactions. © 2013 Verlag der Zeitschrift für Naturforschung, Tübingen.

  8. Proposal of an Algorithm to Synthesize Music Suitable for Dance

    Science.gov (United States)

    Morioka, Hirofumi; Nakatani, Mie; Nishida, Shogo

    This paper proposes an algorithm for synthesizing music suitable for emotions in moving pictures. Our goal is to support multi-media content creation; web page design, animation films and so on. Here we adopt a human dance as a moving picture to examine the availability of our method. Because we think the dance image has high affinity with music. This algorithm is composed of three modules. The first is the module for computing emotions from an input dance image, the second is for computing emotions from music in the database and the last is for selecting music suitable for input dance via an interface of emotion.

  9. Algorithms for Synthesizing Priorities in Component-based Systems

    CERN Document Server

    Cheng, Chih-Hong; Chen, Yu-Fang; Yan, Rongjie; Jobstmann, Barbara; Ruess, Harald; Buckl, Christian; Knoll, Alois

    2011-01-01

    We present algorithms to synthesize component-based systems that are safe and deadlock-free using priorities, which define stateless-precedence between enabled actions. Our core method combines the concept of fault-localization (using safety-game) and fault-repair (using SAT for conflict resolution). For complex systems, we propose three complementary methods as preprocessing steps for priority synthesis, namely (a) data abstraction to reduce component complexities, (b) alphabet abstraction and #-deadlock to ignore components, and (c) automated assumption learning for compositional priority synthesis.

  10. Syntheses of DL-threo-Thiamphenicol via Green Oxidation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Four methyl aryl thioethers related to thiamphenicol syntheses and methyl phenyl sulfide were cleanly oxidized into methyl sulfones in high to excellent yields via catalytic green oxidation with aqueous hydrogen peroxide in combination with sodium tungstate. When the same reactions were similarly performed in the absence of the catalyst, the corresponding sulfoxides could be obtained. This viable synthetic approach for the synthesis of DL-threo-thiamphenicol is a simple procedure, which has an economic advantage in view of its application for the large-scale synthesis because it can be carried out under mild conditions.

  11. Syntheses and characterizations of three acid-base supramolecular complexes

    International Nuclear Information System (INIS)

    Three acid-base compounds with supramolecular architectures, namely, (1,2-H2bdc)(dmt) (1), (trans-1,4-H2ccdc)0.5(phdat) (2) and (1,3-H2bdc)(phdat) (3) (1,2-H2bdc = 1,2-benzenedicarboxylic acid, trans-1, 4-H2ccdc = trans-1, 4-cyclohexanedicarboxylic acid, 1,3-H2bdc = 1,3-benzenedicarboxylic acid, dmt = 2,4-diamino-6-methyl-s-triazine, phdat = 2,4-diamino-6-phenyl-s-triazine) have been synthesized and characterized by IR spectra, elemental analyses, single-crystal X-ray diffractions and TGA. (author)

  12. A NEW METHOD TO SYNTHESIZE THE CATIONIC GRAFT STARCH

    Institute of Scientific and Technical Information of China (English)

    Lin Li; Bingyue Liu; Yafeng Cao

    2004-01-01

    The cationic graft copolymer was synthesized by reversed phase emulsion copolymerization of starch with diallydimethyl ammoniumlchlorid (DADMAC)and acrylamide (AM). The copolymerization was carried out using (NH4)2S2O8-NH2CONH2 redox as initiator and selecting Span-20 as emulsifier. The effects of emulsifier content in oil phase, volume ratio of oil to water, initiator concentration and mole ratio of DADMAC to AM on the graft copolymerization were discussed. The optimum condition of synthetics was found with the orthogonal test method.

  13. Comparative sinterability of combustion synthesized and commercial titanium carbides

    International Nuclear Information System (INIS)

    The influence of various parameters on the sinterability of combustion synthesized titanium carbide was investigaged. Titanium carbide powders, prepared by the combustion synthesis process, were sintered in the temperature range 1150 to 16000C. Incomplete combustion and high oxygen contents were found to be the cause of reduced shrinkage during sintering of the combustion syntheized powders when compared to the shrinkage of commercial TiC. Free carbon was shown to inhibit shrinkage. The activation energy for sintering was found to depend on stoichiometry (C/Ti). With decreasing C/Ti, the rate of sintering increased. 29 references, 16 figures, 13 tables

  14. Reduktive Synthese zu neuartigen cyclischen und acyclischen Borverbindungen

    OpenAIRE

    Claes, Christina

    2016-01-01

    Ein Teil der hier vorliegenden Arbeit beschäftigte sich mit der Synthese und Charakterisierung neuer Boran-Addukte. Dabei wurden neben den NHCs IMe und IMeMe die Phosphane PEt3 und PMe3 als stabilisierende Lewisbasen eingesetzt. Neben dem Liganden wurde auch der borgebundene organische Rest variiert (Phenyl und n-Butyl), um deren Einfluss auf die Eigenschaften der Addukte zu untersuchen. Die NHC-stabilisierten Monoborane IMe∙B(nBu)Cl2 (99) und IMeMe∙B(Ph)Cl2 (100) konnten in guten Ausbeuten i...

  15. Nanostructured superhydrophobic films synthesized by electrodeposition of fluorinated polyindoles

    OpenAIRE

    Gabriela Ramos Chagas; Thierry Darmanin; Frédéric Guittard

    2015-01-01

    Materials with bioinspired superhydrophobic properties are highly desirable for many potential applications. Here, nine novel monomers derived from indole are synthesized to obtain these properties by electropolymerization. These monomers differ by the length (C4F9, C6F13 and C8F17) and the position (4-, 5- and 6-position of indole) of the perfluorinated substituent. Polymeric films were obtained with C4F9 and C6F13 chains and differences in the surface morphology depend especially on the sub...

  16. Photopolymerization of C60 crystal synthesized from organic solution

    International Nuclear Information System (INIS)

    We have been developing a novel process to synthesize C60 polymers as superior functional materials. Polymerization reactions of C60 precipitated from organic solution were investigated under Free Electron Laser (FEL) irradiation. The two processes: a liquid-liquid interfacial precipitation (LLIP) method and an evaporation technique from supersaturated solution, were studied with a respect of crystal structure and/or Raman spectrum for the precipitates before and after FEL irradiation. It was found that the photopolymerization reaction took place effectively in the LLIP precipitate because of its highly packed molecular crystal structure.

  17. Practical Large Scale Syntheses of New Drug Candidates

    Institute of Scientific and Technical Information of China (English)

    Hui-Yin Li

    2001-01-01

    @@ This presentation will be focus on Practical large scale syntheses of lead compounds and drug candidates from three major therapeutic areas from DuPont Pharmaceuticals Research Laboratory: 1). DMP777-a selective, non-toxic, orally active human elastase inhibitor; 2). DMP754-a potent glycoprotein IIb/IIIa antagonist; 3). R-Wafarin-the pure enantiomeric form of wafarin. The key technology used for preparation these drug candidates is asymmetric hydrogenation under very mild reaction conditions, which produced very high quality final products at large scale (>99% de, >99 A% and >99 wt%). Some practical and GMP aspects of process development will be also discussed.

  18. Practical Large Scale Syntheses of New Drug Candidates

    Institute of Scientific and Technical Information of China (English)

    Hui-Yin; Li

    2001-01-01

    This presentation will be focus on Practical large scale syntheses of lead compounds and drug candidates from three major therapeutic areas from DuPont Pharmaceuticals Research Laboratory: 1). DMP777-a selective, non-toxic, orally active human elastase inhibitor; 2). DMP754-a potent glycoprotein IIb/IIIa antagonist; 3). R-Wafarin-the pure enantiomeric form of wafarin. The key technology used for preparation these drug candidates is asymmetric hydrogenation under very mild reaction conditions, which produced very high quality final products at large scale (>99% de, >99 A% and >99 wt%). Some practical and GMP aspects of process development will be also discussed.……

  19. Annual reports in inorganic and general syntheses 1976

    CERN Document Server

    Zimmer, Hans

    2013-01-01

    Annual Reports in Inorganic and General Syntheses-1976 presents an annual review of synthetically useful information that would prove beneficial to nearly all organic chemists, both specialist and nonspecialist in synthesis. It should help relieve some of the information storage burden of the specialist and should aid the nonspecialist who is seeking help with a specific problem to become rapidly aware of recent synthetic advances.This is the fifth volume of ARIGS and is organized along the lines developed for the preceding volumes. The authors were encouraged to use synthetic aspects as their

  20. Integrated digital superconducting logic circuits for the quantum synthesizer. Report

    International Nuclear Information System (INIS)

    This report presents the results, which were reached in the framework of the BMBF cooperative plan ''Quantum Synthesizer'' in the partial plan ''Integrated Digital Superconducting Logic Circuits''. As essential goal of the plan a novel instrument on the base of quantum-coherent superconducting circuits should be developed. which allows to generate praxis-relevant wave forms with quantum accuracy, the quantum synthesizer. The main topics of development of the reported partial plan lied at the one hand in the development of integrated, digital, superconducting circuit in rapid-single-flux (RSFQ) quantum logics for the pattern generator of the quantum synthesizer, at the other hand in the further development of the fabrication technology for the aiming of high circuit complexity. In order to fulfil these requirements at the PTB a new design system was implemented, based on the software of Cadence. Together with the required RSFQ extensions for the design of digital superconducting circuits was a platform generated, on which the reachable circuit complexity is exclusively limited by the technology parameters of the available fabrication technology: Physical simulations are with PSCAN up to a complexity of more than 1000 circuit elements possible; furthermore VHDL allows the verification of arbitrarily large circuit architectures. In accordance for this the production line at the PTB was brought to a level, which allows in Nb/Al-AlxOy/Nb SIS technology implementation the fabrication of highly integrable RSFQ circuit architectures. The developed and fabricated basic circuits of the pattern generator have proved correct functionality and reliability in the measuring operation. Thereby for the circular RSFQ shift registers a key role as local memories in the construction of the pattern generator is devolved upon. The registers were realized with the aimed bit lengths up to 128 bit and with reachable signal-processing speeds of above 10 GHz. At the interface RSFQ

  1. Bio-inspired routes for synthesizing efficient nanoscale platinum electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Jennifer N. [Univ. of California, San Diego, CA (United States); Wang, Joseph [Univ. of California, San Diego, CA (United States)

    2014-08-31

    The overall objective of the proposed research is to use fundamental advances in bionanotechnology to design powerful platinum nanocrystal electrocatalysts for fuel cell applications. The new economically-viable, environmentally-friendly, bottom-up biochemical synthetic strategy will produce platinum nanocrystals with tailored size, shape and crystal orientation, hence leading to a maximum electrochemical reactivity. There are five specific aims to the proposed bio-inspired strategy for synthesizing efficient electrocatalytic platinum nanocrystals: (1) isolate peptides that both selectively bind particular crystal faces of platinum and promote the nucleation and growth of particular nanocrystal morphologies, (2) pattern nanoscale 2-dimensional arrays of platinum nucleating peptides from DNA scaffolds, (3) investigate the combined use of substrate patterned peptides and soluble peptides on nanocrystal morphology and growth (4) synthesize platinum crystals on planar and large-area carbon electrode supports, and (5) perform detailed characterization of the electrocatalytic behavior as a function of catalyst size, shape and morphology. Project Description and Impact: This bio-inspired collaborative research effort will address key challenges in designing powerful electrocatalysts for fuel cell applications by employing nucleic acid scaffolds in combination with peptides to perform specific, environmentally-friendly, simultaneous bottom-up biochemical synthesis and patterned assembly of highly uniform and efficient platinum nanocrystal catalysts. Bulk synthesis of nanoparticles usually produces a range of sizes, accessible catalytic sites, crystal morphologies, and orientations, all of which lead to inconsistent catalytic activities. In contrast, biological systems routinely demonstrate exquisite control over inorganic syntheses at neutral pH and ambient temperature and pressures. Because the orientation and arrangement of the templating biomolecules can be precisely

  2. Antibacterial screening of silver nanoparticles synthesized by marine micro algae

    Institute of Scientific and Technical Information of China (English)

    D Devina Merin; S Prakash; B Valentine Bhimba

    2010-01-01

    Objective:To explore the biosynthesis of silver nanoparticles synthesized by marine microalgae. Methods: Marine microalgae was collected from Central Marine Fisheries Research Institute (CMFRI, tuticorin) and cultured in the lab. Silver nanoparticles synthesis were observed in normal and microwave irradiated microalgae and screened against human pathogens for the presence of antimicrobials.Results: The presence of silver nanoparticle was confirmed by UV-Visible spectroscopy at420 nm by the presence of plasmon peak. Further confirmation was done by scanning electron microscope(SEM).Conclusions: These results not only provide a base for further research but are useful for drug development in the present and future.

  3. Dynamic balancing of mechanisms and synthesizing of parallel robots

    CERN Document Server

    Wei, Bin

    2016-01-01

    This book covers the state-of-the-art technologies in dynamic balancing of mechanisms with minimum increase of mass and inertia. The synthesis of parallel robots based on the Decomposition and Integration concept is also covered in detail. The latest advances are described, including different balancing principles, design of reactionless mechanisms with minimum increase of mass and inertia, and synthesizing parallel robots. This is an ideal book for mechanical engineering students and researchers who are interested in the dynamic balancing of mechanisms and synthesizing of parallel robots. This book also: ·       Broadens reader understanding of the synthesis of parallel robots based on the Decomposition and Integration concept ·       Reinforces basic principles with detailed coverage of different balancing principles, including input torque balancing mechanisms ·       Reviews exhaustively the key recent research into the design of reactionless mechanisms with minimum increase of mass a...

  4. Design of S-Band Frequency Synthesizer for Microwave Applications

    Directory of Open Access Journals (Sweden)

    S. Shurender

    2013-08-01

    Full Text Available A phase locked loop based indirect frequency synthesizer is designed for S-band frequency. A Phase locked loop is designed and the phase noise response and transient response of the designed PLL is simulated for 2100MHz frequency. The phase noise response of total PLL and its individual components are obtained. A 3rd order low pass passive loop filter is used and by varying the loop bandwidth and phase margin the trade-off between lock time and phase noise is observed and an optimum value of loop bandwidth and phase margin is chosen such that its phase noise contribution is less. The designed phase locked loop has a low phase noise value of -112.4dBc/Hz at 100 kHz offset frequency and has a fast lock time of 119.5 us. The time taken by the designed frequency synthesizer to lock to 10 Hz frequency error and 1° phase error under transient conditions is found to be 149 us and 116 us respectively. The RMS phase jitter obtained for the designed phase locked loop is 0.3° rms. The phase locked loop is designed and simulated using ADIsimPLL tool. The phase locked loop design aims at achieving low phase noise, reduced lock time and high reliability for S-band applications.

  5. Metal Borohydrides synthesized from metal borides and metal hydrides

    DEFF Research Database (Denmark)

    Sommer, Sanna

    2014-01-01

    and Ca(BH4)2, respectively [3,4]. An attempt to synthesize alkali and alkaline earth metal borohydrides from various borides by ball milling under high hydrogen pressure is presented here. MgB2, AlB2 and CaB6 have been milled with MHx (M = Li, Na, Mg, Ca) at p(H2) = 110 bar for 24 hours. All samples......Metal Borohydrides Synthesized from Metal Borides and Metal Hydrides Alexander Fogha, Sanna Sommera, Kasper T. Møllera, T. R. Jensena aCenter for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO) and Chemistry Department, Aarhus University, Langelandsgade 140, DK-8000...... Aarhus C, Denmark email: gallafogh@hotmail.com / sanna-sommer@hotmail.com Magnesium boride, MgB2, ball milled with MH (M = Li, Na, Ca) followed by hydrogenation under high hydrogen pressure, readily forms the corresponding metal borohydrides, M(BH4)x (M = Li, Na, Ca) and MgH2 according to reaction scheme...

  6. Multifunctional Martian habitat composite material synthesized from in situ resources

    Science.gov (United States)

    Sen, S.; Carranza, S.; Pillay, S.

    2010-09-01

    The two primary requirements for a Martian habitat structure include effective radiation shielding against the Galactic Cosmic Ray (GCR) environment and sufficient structural and thermal integrity. To significantly reduce the cost associated with transportation of such materials and structures from earth, it is imperative that such building materials should be synthesized primarily from Martian in situ resources. This paper illustrates the feasibility of such an approach. Experimental results are discussed to demonstrate the synthesis of polyethylene (PE) from a simulated Martian atmosphere and the fabrication of a composite material using simulated Martian regolith with PE as the binding material. The radiation shielding effectiveness of the proposed composites is analyzed using results from radiation transport codes and exposure of the samples to high-energy beams that serve as a terrestrial proxy for the GCR environment. Mechanical and ballistic impact resistance properties of the proposed composite as a function of composition, processing parameters, and thermal variations are also discussed to evaluate the multifunctionality of such in situ synthesized composite materials.

  7. Erythropoietin is involved in hemoprotein syntheses in developing human decidua.

    Science.gov (United States)

    Shiota, Mitsuru; Yasuda, Yoshiko; Shimaoka, Masao; Tsuritani, Mitsuhiro; Koike, Eiji; Oiki, Masaaki; Matsubara, Junko; Taketani, Shigeru; Murakami, Hitoshi; Yamasaki, Harufumi; Okumoto, Katsumi; Hoshiai, Hiroshi

    2013-03-01

    Before establishment of feto-placental circulation, decidua can synthesize hemoproteins to maintain oxygen homeostasis in situ. Using the human decidua of induced abortions ranging from 5 to 8 weeks of gestation, we determined the expression levels of erythropoietin, erythropoietin receptor, cytoglobin, myoglobin, embryonic-, fetal- and adult hemoglobin mRNA by quantitative RT-PCR analysis and identified their proteins by Western blot and immunohistochemical analyses. Erythropoietin signaling was demonstrated in phosphatidylinositol-3-kinase/protein kinase B pathway by Western blot, and the transcriptional factors for erythroid and non-erythroid heme synthesis were examined by RT-PCR analysis. In decidua, erythropoietin and its receptor mRNAs, erythropoietin receptor protein and phosphatidylinositol-3-kinase, were expressed with a peak at 6 weeks of gestation. Moreover, the decidua during 5 to 8 weeks of gestation expressed embryonic, fetal and adult hemoglobins additionally cytoglobin and myoglobin at transcriptional and protein levels. The heme portion of these hemoproteins is considered to be synthesized by non-erythroid δ-aminolevulinate synthase. These hemoproteins were discernible especially in decidual cells concomitant with cytotrophoblast cells and macrophage in these developing decidua. Considering the different capacity for oxygen binding and dissociation among hemoglobins with the oxygen storage capacity for cytoglobin and myoglobin, these hemoproteins appear to play a role in oxygen demand in decidua in situ before development of feto-placental circulation under the control of erythropoietin signaling. PMID:23480354

  8. Construction of a cyanobacterium synthesizing cyclopropane fatty acids.

    Science.gov (United States)

    Machida, Shuntaro; Shiraiwa, Yoshihiro; Suzuki, Iwane

    2016-09-01

    Microalgae have received much attention as a next-generation source of biomass energy. However, most of the fatty acids (FAs) from microalgae are multiply unsaturated; thus, the biofuels derived from them are fluid, but vulnerable to oxidation. In this study, we attempted to synthesize cyclopropane FAs in the cyanobacterium Synechocystis sp. PCC 6803 by expressing the cfa gene for cyclopropane FA synthase from Escherichia coli with the aim of producing FAs that are fluid and stable in response to oxidization. We successfully synthesized cyclopropane FAs in Synechocystis with a yield of ~30% of total FAs. Growth of the transformants was altered, particularly at low temperatures, but photosynthesis and respiration were not significantly affected. C16:1(∆9) synthesis in the desA(-)/desD(-) strain by expression of the desC2 gene for sn-2 specific ∆9 desaturase positively affected growth at low temperatures via promotion of various cellular processes, with the exceptions of photosynthesis and respiration. Estimation of the apparent activities of desaturases suggested that some acyl-lipid desaturases might recognize the lipid side chain. PMID:27263419

  9. Alternative methods of synthesizing 99Tcm-labelled ciprofloxacin

    International Nuclear Information System (INIS)

    Full text: 99Tcm-labelled ciprofloxacin (Infecton) is a new class of radiopharmaceutical designed for imaging live bacterial infection. We synthesized Infecton by modifying the procedure described by Keith Britton's group (Lancet 1996; 347: 233-235) and reported our findings at the ANZSNM meeting last year. Since the methodology was cumbersome, we investigated simpler alternative ways of labelling ciprofloxacin with 99Tcm-pertechnetate for routine imaging. There were several limitations in the previously described method: (1) Need to prepare pure ciprofloxacin which was unstable on storage. (2) Synthetic procedure using formimidine sulphinic acid (FSA) was complicated and required boiling step. (3) The radiochemical purity (RCP) of the product was low (45-50%) requiring purification. (4) Biodistribution studies showed a marked uptake by the liver which could interfere with scan interpretation in this region. The results of our present studies showed that Infecton could be prepared by a simple two-step method: (1) Reduce 99Tcm-pertechnetate with stannous salt (SnCl2 or Sn-tartrate). (2) Mix with Ciproxin IV-100. The RCP of the product was up to 98%, which obviates the need for further purification. Infecton synthesized by the above method showed avid localization in abscesses induced with Staphylococcus aureus in rats. The biodistribution studies showed that Infecton was renally excreted with minimal accumulation in the liver or other organs

  10. A green chemistry approach for synthesizing biocompatible gold nanoparticles

    Science.gov (United States)

    Gurunathan, Sangiliyandi; Han, JaeWoong; Park, Jung Hyun; Kim, Jin-Hoi

    2014-05-01

    Gold nanoparticles (AuNPs) are a fascinating class of nanomaterial that can be used for a wide range of biomedical applications, including bio-imaging, lateral flow assays, environmental detection and purification, data storage, drug delivery, biomarkers, catalysis, chemical sensors, and DNA detection. Biological synthesis of nanoparticles appears to be simple, cost-effective, non-toxic, and easy to use for controlling size, shape, and stability, which is unlike the chemically synthesized nanoparticles. The aim of this study was to synthesize homogeneous AuNPs using pharmaceutically important Ganoderma spp . We developed a simple, non-toxic, and green method for water-soluble AuNP synthesis by treating gold (III) chloride trihydrate (HAuCl4) with a hot aqueous extract of the Ganoderma spp . mycelia. The formation of biologically synthesized AuNPs (bio-AuNPs) was characterized by ultraviolet (UV)-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray (EDX), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the biocompatibility of as-prepared AuNPs was evaluated using a series of assays, such as cell viability, lactate dehydrogenase leakage, and reactive oxygen species generation (ROS) in human breast cancer cells (MDA-MB-231). The color change of the solution from yellow to reddish pink and strong surface plasmon resonance were observed at 520 nm using UV-visible spectroscopy, and that indicated the formation of AuNPs. DLS analysis revealed the size distribution of AuNPs in liquid solution, and the average size of AuNPs was 20 nm. The size and morphology of AuNPs were investigated using TEM. The biocompatibility effect of as-prepared AuNPs was investigated in MDA-MB-231 breast cancer cells by using various concentrations of AuNPs (10 to 100 μM) for 24 h. Our findings suggest that AuNPs are non-cytotoxic and biocompatible. To the best of our knowledge

  11. Using singlet oxygen to synthesize polyoxygenated natural products from furans.

    Science.gov (United States)

    Montagnon, Tamsyn; Tofi, Maria; Vassilikogiannakis, Georgios

    2008-08-01

    [Reaction: see text]. Singlet oxygen is a powerful tool in the armament of the synthetic organic chemist and possibly in that of nature itself. In this Account, we illustrate a small selection of the many ways singlet oxygen can be harnessed in the laboratory to aid in the construction of the complex molecular motifs found in natural products. A more philosophical question is also addressed: namely, how much do singlet oxygen oxidations influence the biogenesis of these natural products? All the synthetic examples surveyed in this Account can be characterized as belonging to the same class because they all involve the oxidation of a substituted furan nucleus by singlet oxygen. Readily accessible and relatively simple furans can be transformed into a host of complex motifs present in a diverse range of natural products by the action of singlet-oxygen-mediated reaction sequences. These reactions are highly advantageous because they frequently deliver a rapid and dramatic increase in molecular complexity in high yield. Furthermore, an unusually wide structural diversity is exhibited by the molecular motifs obtained from these reaction sequences. For example, relatively minor modifications to the starting substrate and to the reaction conditions may lead to products as variable as spiroketal lactones, 3-keto-tetrahydrofurans, various types of bis-spiroketals, 4-hydroxy cyclopentenones, or spiroperoxylactones. In addition, two more specialized examples are discussed in this Account. The core of the prunolide molecules and the chinensine family of natural products were rapidly synthesized using effective and short singlet oxygen mediated strategies; this adds weight to the assertion that singlet oxygen is a very effective moderator of complex cascade reaction sequences. We also show how our synthetic investigations have provided evidence that these same strategies might be used in the biogenesis of these molecules. In the cases of the chinensines and the

  12. Characterization of chemically synthesized CdS nanoparticles

    Indian Academy of Sciences (India)

    Rajeev R Prabhu; M Abdul Khadar

    2005-11-01

    II–VI semiconductor nanoparticles are presently of great interest for their practical applications such as zero-dimensional quantum confined materials and for their applications in optoelectronics and photonics. The optical properties get modified dramatically due to the confinement of charge carriers within the nanoparticles. Similar to the effects of charge carriers on optical properties, confinement of optical and acoustic phonons leads to interesting changes in the phonon spectra. In the present work, we have synthesized nanoparticles of CdS using chemical precipitation technique. The crystal structure and grain size of the particles are studied using XRD. The UV–visible absorption, photoluminescence and Raman spectra of the sample are recorded and discussed briefly.

  13. Progress of synthesizing methods and properties of fluorinated carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this paper,the recent development of fluorinated carbon nanotubes(F-CNTs) was introduced.The synthesizing methods of F-CNTs,including direct fluorination and plasma treatment,were discussed in detail,and the effects of factors,such as the temperature and pressure in fluorination as well as the kind of fluorine source and carbon nanotubes,on the structures and properties of F-CNTs were also summarized.In the mean time,the special physical and chemical properties of F-CNTs and the relevant applied fields were described briefly,the exisiting problems of F-CNTs were summed up,and the direction of future development was also discussed in the end.

  14. Mesoporous silica magnetite nanocomposite synthesized by using a neutral surfactant

    Science.gov (United States)

    Souza, K. C.; Salazar-Alvarez, G.; Ardisson, J. D.; Macedo, W. A. A.; Sousa, E. M. B.

    2008-05-01

    Magnetite nanoparticles coated by mesoporous silica were synthesized by an alternative chemical route using a neutral surfactant and without the application of any functionalization method. The magnetite (Fe3O4) nanoparticles were prepared by precipitation from aqueous media, and then coated with mesoporous silica by using nonionic block copolymer surfactants as the structure-directing agents. The mesoporous SiO2-coated Fe3O4 samples were characterized by x-ray diffraction, Fourier-transform infrared spectroscopy, N2 adsorption-desorption isotherms, transmission electron microscopy, 57Fe Mössbauer spectroscopy, and vibrating sample magnetometry. Our results revealed that the magnetite nanoparticles are completely coated by well-ordered mesoporous silica with free pores and stable (~8 nm thick) pore walls, and that the structural and magnetic properties of the Fe3O4 nanoparticles are preserved in the applied synthesis route.

  15. The stabilization and targeting of surfactant-synthesized gold nanorods

    International Nuclear Information System (INIS)

    The strong cetyltrimethylammonium bromide (CTAB) surfactant responsible for the synthesis and stability of gold nanorod solutions complicates their biomedical applications. The critical parameter to maintain nanorod stability is the ratio of CTAB to nanorod concentration. The ratio is approximately 740 000 as determined by chloroform extraction of the CTAB from a nanorod solution. A comparison of nanorod stabilization by thiol-terminal PEG and by anionic polymers reveals that PEGylation results in higher yields and less aggregation upon removal of CTAB. A heterobifunctional PEG yields nanorods with exposed carboxyl groups for covalent conjugation to antibodies with the zero-length carbodiimide linker EDC. This conjugation strategy leads to approximately two functional antibodies per nanorod according to fluorimetry and ELISA assays. The nanorods specifically targeted cells in vitro and were visible with both two-photon and confocal reflectance microscopies. This covalent strategy should be generally applicable to other biomedical applications of gold nanorods as well as other gold nanoparticles synthesized with CTAB.

  16. Electrospray deposition of isolated chemically synthesized magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Agostini, Pierre; Meffre, Anca; Lacroix, Lise-Marie; Ugnati, Damien [Université de Toulouse (France); INSA, UPS, CNRS, Laboratoire de Physique et Chimie des Nano-objets (LPCNO) (France); Ondarçuhu, Thierry [Centre d’Elaboration de Matériaux et d’Etudes Structurales (CEMES-CNRS) (France); Respaud, Marc; Lassagne, Benjamin, E-mail: lassagne@insa-toulouse.fr [Université de Toulouse (France); INSA, UPS, CNRS, Laboratoire de Physique et Chimie des Nano-objets (LPCNO) (France)

    2016-01-15

    The deposition of isolated magnetic nanoparticles onto a substrate was performed using electrohydrodynamic spraying. Two kinds of nanoparticles were sprayed, 11 nm CoFe carbide nanospheres and 10.5 nm Fe nanocubes. By studying carefully the evolution of the sprayed charged droplets and the mechanism of nanoparticle dispersion in them, we could optimize the nanoparticle concentration within the initial nanoparticle solution (i) to reduce the magnetic interaction and therefore prevent agglomeration and (ii) to obtain in a relatively short period (1 h) a deposit of isolated magnetic nanoparticles with a density of up to 400 nanoparticles per µm{sup 2}. These results open great perspectives for magnetic measurements on single objects using advanced magnetometry techniques as long as spintronics applications based on single chemically synthesized magnetic nanoparticles.

  17. SPPS Resins Impact the PNA-Syntheses' Improvement

    Science.gov (United States)

    Pipkorn, Rüdiger; Rawer, Stephan; Wiessler, Manfred; Waldeck, Waldemar; Koch, Mario; Schrenk, Hans Hermann; Braun, Klaus

    2013-01-01

    The personalized medicine, also documented as “individualized medicine”, is an effective and therapeutic approach. It is designed to treat the disease of the individual patient whose precise differential gene expression profile is well known. The trend in the biomedical and biophysical research shows important consequences for the pharmaceutical drug and diagnostics research. It requires a high variability in the design and safety of target-specific pharmacologically active molecules and diagnostic components for imaging of metabolic processes. A key technology which may fulfill the highest demands during synthesis of these individual drugs and diagnostics is the solid phase synthesis which is congenial to automated manufacturing. Additionally the choice of tools like resins and reagents is pivotal to synthesize drugs and diagnostics in high quality and yields. Here we demonstrate the solid phase synthesis effects dependent on the choice of resin and of the deprotection agent. PMID:23423830

  18. Design of a Synthesizing Lecture on Mechanics Concepts

    Science.gov (United States)

    Strand, Natalie E.; Docktor, Jennifer L.; Gladding, Gary E.; Mestre, José P.; Ross, Brian H.

    2010-10-01

    Within the context of traditional physics problem solving instruction, major concepts are mentioned but often marginalized by the focus on equation manipulation, resulting in students perceiving concepts as unimportant in problem solving. Additionally, since topics are covered as isolated pieces, students also perceive concepts as unrelated. In response to this disconnect, we discuss the development of a short, animated, web-delivered synthesizing presentation modeled after the "common learning resource" from the preparation for future learning construct. In the presentation, major concepts of introductory mechanics are structured hierarchically. More specifically, the presentation is an overview of major theorems and conservation laws in mechanics and the conditions under which they are applied. It is linked to previous problems solved by the students and intended to prepare them for future learning by illustrating how concepts guide problem solving processes.

  19. Method for synthesizing metal bis(borano) hypophosphite complexes

    Science.gov (United States)

    Cordaro, Joseph G.

    2013-06-18

    The present invention describes the synthesis of a family of metal bis(borano) hypophosphite complexes. One procedure described in detail is the syntheses of complexes beginning from phosphorus trichloride and sodium borohydride. Temperature, solvent, concentration, and atmosphere are all critical to ensure product formation. In the case of sodium bis(borano) hypophosphite, hydrogen gas was evolved upon heating at temperatures above 150.degree. C. Included in this family of materials are the salts of the alkali metals Li, Na and K, and those of the alkaline earth metals Mg and Ca. Hydrogen storage materials are possible. In particular the lithium salt, Li[PH.sub.2(BH.sub.3).sub.2], theoretically would contain nearly 12 wt % hydrogen. Analytical data for product characterization and thermal properties are given.

  20. Oestradiol synthesized by female neurons generates sex differences in neuritogenesis

    Science.gov (United States)

    Ruiz-Palmero, Isabel; Ortiz-Rodriguez, Ana; Melcangi, Roberto Cosimo; Caruso, Donatella; Garcia-Segura, Luis M.; Rune, Gabriele M.; Arevalo, Maria-Angeles

    2016-01-01

    Testosterone produced by the foetal testis is converted by male neurons to oestradiol, which masculinizes neuronal morphology. Female neurons are known to synthesize oestradiol in absence of exogenous testosterone. However, the role of neuronal oestradiol on the differentiation of foetal female neurons is unknown. Here we show that, due to endogenous neuronal oestradiol synthesis, female hippocampal neurons have higher expression of the neuritogenic protein Neurogenin 3 and enhanced neuritogenesis than males. Exogenous application of testosterone or its metabolite dihydrotestosterone increases Neurogenin 3 expression and promotes neuritogenesis in males, but reduces these parameters in females. Together our data indicate that gonadal-independent oestradiol synthesis by female neurons participates in the generation of sex differences in hippocampal neuronal development. PMID:27553191

  1. Expectations and limits to synthesize nuclei with Z ≥ 120

    International Nuclear Information System (INIS)

    In order to explore the possibilities to synthesize the new superheavy elements with Z=120, 122, 124, 126 some hot-fusion (mass asymmetric) reactions and cold-fusion (less mass asymmetric) reactions are studied. The dynamics of reaction with massive nuclei and the formation probability of heavy and superheavy elements with Z=90-126 in the asymmetric and symmetric reactions are discussed. The systematics of fusion probability PCN and evaporation residue cross section σER in these reactions are presented. Moreover, we explore the possibility of synthesis of superheavy nuclei by the use of reaction with the neutron rich radioactive beam 132Sn, and by symmetric reactions like 136Xe+136Xe and 139,149La+ 139,149La. (author)

  2. Enhanced photocatalytic activity of electrochemically synthesized aluminum oxide nanoparticles

    Science.gov (United States)

    Pathania, Deepak; Katwal, Rishu; Kaur, Harpreet

    2016-03-01

    In this study, aluminum oxide (Al2O3) nanoparticles (NPs) were synthesized via an electrochemical method. The effects of reaction parameters such as supporting electrolytes, solvent, current and electrolysis time on the shape and size of the resulting NPs were investigated. The Al2O3 NPs were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, thermogravimetric analysis/differential thermal analysis, energy-dispersive X-ray analysis, and ultraviolet-visible spectroscopy. Moreover, the Al2O3 NPs were explored for photocatalytic degradation of malachite green (MG) dye under sunlight irradiation via two processes: adsorption followed by photocatalysis; coupled adsorption and photocatalysis. The coupled process exhibited a higher photodegradation efficiency (45%) compared to adsorption followed by photocatalysis (32%). The obtained kinetic data was well fitted using a pseudo-first-order model for MG degradation.

  3. Shape dependent heat transport through green synthesized gold nanofluids

    International Nuclear Information System (INIS)

    Nanofluids hold promise as a more efficient coolant for thermoelectric devices. Despite the capability of tailoring the thermo physical properties of nanofluids, by tuning the particle parameters such as shape, size and concentration, the toxicity of chemicals used for the preparation of nanoparticles is a serious concern. Green synthesis of nanoparticles is emerging as an alternative to the conventional chemical and physical methods for the preparation of nanoparticles. In this work, the results of the preparation of gold nanoparticles using plant extracts as reducing agents are presented. The green synthesis route employed for the present study provides particles of similar size, but the shape of the particles is found to vary depending upon the source of the natural reducing agents. The thermal diffusivity values of the gold nanofluid measured using laser based dual beam thermal lens technique elucidate the role of shape and concentration of the green synthesized nanoparticles on the effective thermal diffusivity values of the nanofluids. (paper)

  4. Thermally stimulated luminescence studies in combustion synthesized polycrystalline aluminum oxide

    Indian Academy of Sciences (India)

    K R Nagabhushana; B N Lakshminarasappa; D Revannasiddaiah; Fouran Singh

    2008-08-01

    Synthesis of materials by combustion technique results in homogeneous and fine crystalline product. Further, the technique became more popular since it not only saved time and energy but also was easy to process. Aluminum oxide phosphor was synthesized by using urea as fuel in combustion reaction. Photoluminescence (PL) and thermally stimulated luminescence (TSL) characteristics of -irradiated aluminum oxide samples were studied. A broad PL emission with a peak at ∼ 465 nm and a pair of strong and sharp emissions with peaks at 679 and 695 nm were observed in -rayed samples. The PL intensity was observed to increase with increase in -ray dose. Two prominent and well resolved TSL glows with peaks at 210°C and 365°C were observed in all -irradiated Al2O3 samples. The TSL intensity was also found to increase with increase in -ray dose. The TSL glow curves indicated second order kinetics.

  5. SiC nanowires synthesized from graphene and silicon vapors

    Science.gov (United States)

    Weichenpei, Luo; Gong-yi, Li; Zengyong, Chu; Tianjiao, Hu; Xiaodong, Li; Xuefei, Zhang

    2016-04-01

    The preparation of silicon carbide (SiC) nanowires is basically important for its potential applications in nanodevices, nanocomposites, etc. In the present work, a simple route was reported to synthesize SiC nanowires by heating commercial graphene with silicon vapors and no catalyst. Characterization by scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, electron energy scattering, X-ray diffraction, and Raman dispersive spectrum demonstrates the products are composed of β-SiC crystal. The SiC nanowires have the average diameter of about 50 nm and length of tens of micrometers. The vapor-solid mechanism was employed to interpret the SiC nanowires growth. Gaseous SiO which was produced by the reaction of Si powders with its surface oxidation reacted with the solid graphene to form SiC crystal nuclei. And SiC crystal nuclei would act as active sites for further growing into nanowires.

  6. Silicon carbide nanowires synthesized with phenolic resin and silicon powders

    Science.gov (United States)

    Zhao, Hongsheng; Shi, Limin; Li, Ziqiang; Tang, Chunhe

    2009-02-01

    Large-scale silicon carbide nanowires with the lengths up to several millimeters were synthesized by a coat-mix, moulding, carbonization, and high-temperature sintering process, using silicon powder and phenolic resin as the starting materials. Ordinary SiC nanowires, bamboo-like SiC nanowires, and spindle SiC nanochains are found in the fabricated samples. The ordinary SiC nanowire is a single-crystal SiC phase with a fringe spacing of 0.252 nm along the [1 1 1] growth direction. Both of the bamboo-like SiC nanowires and spindle SiC nanochains exhibit uniform periodic structures. The bamboo-like SiC nanowires consist of amorphous stem and single-crystal knots, while the spindle SiC nanochains consist of uniform spindles which grow uniformly on the entire nanowires.

  7. Nanostructured superhydrophobic films synthesized by electrodeposition of fluorinated polyindoles

    Directory of Open Access Journals (Sweden)

    Gabriela Ramos Chagas

    2015-10-01

    Full Text Available Materials with bioinspired superhydrophobic properties are highly desirable for many potential applications. Here, nine novel monomers derived from indole are synthesized to obtain these properties by electropolymerization. These monomers differ by the length (C4F9, C6F13 and C8F17 and the position (4-, 5- and 6-position of indole of the perfluorinated substituent. Polymeric films were obtained with C4F9 and C6F13 chains and differences in the surface morphology depend especially on the substituent position. The polyindoles exhibited hydrophobic and superhydrophobic properties even with a very low roughness. The best results are obtained with PIndole-6-F6 for which superhydrophobic and highly oleophobic properties are obtained due to the presence of spherical nanoparticles and low surface energy compounds.

  8. Dielectric Properties of CDS Nanoparticles Synthesized by Soft Chemical Route

    Indian Academy of Sciences (India)

    R Tripathi; A Kumar; T P Sinha

    2009-06-01

    CdS nanoparticles have been synthesized by a chemical reaction route using thiophenol as a capping agent. The frequency-dependent dielectric dispersion of cadmium sulphide (CdS) is investigated in the temperature range of 303–413 K and in a frequency range of 50 Hz–1 MHz by impedance spectroscopy. An analysis of the complex per-mittivity ( and ) and loss tangent (tan ) with frequency is performed by assuming a distribution of relaxation times. The scaling behaviour of dielectric loss spectra sug- gests that the relaxation describes the same mechanism at various temperatures. The frequency-dependent electrical data are analysed in the framework of conductivity and modulus formalisms. The frequency-dependent conductivity spectra obey the power law.

  9. Helical polyacetylene synthesized with a chiral nematic reaction field

    Science.gov (United States)

    Akagi; Piao; Kaneko; Sakamaki; Shirakawa; Kyotani

    1998-11-27

    Helical polyacetylene was synthesized under an asymmetric reaction field consisting of chiral nematic (N*) liquid crystals (LCs). The chiral nematic LC was prepared by adding a chiroptical binaphthol derivative as a chiral dopant to a mixture of two nematic LCs. Acetylene polymerizations were carried out using the catalyst titanium tetra-n-butoxide-triethylaluminum dissolved in the chiral nematic LC solvent. The polyacetylene film was shown by scanning electron microscopy to consist of clockwise or counterclockwise helical structure of fibrils. A Cotton effect was observed in the region of the pi --> pi* transition of the polyacetylene chain in circular dichroism spectra. The high electrical conductivities of approximately 1500 to 1800 siemens per centimeter after iodine doping and the chiral helicity of these films may be exploited in electromagnetic and optical applications. PMID:9831554

  10. Electrochemical behavior of chemically synthesized selenium thin film.

    Science.gov (United States)

    Patil, A M; Kumbhar, V S; Chodankar, N R; Lokhande, A C; Lokhande, C D

    2016-05-01

    The facile and low cost simple chemical bath deposition (CBD) method is employed to synthesize red colored selenium thin films. These selenium films are characterized for structural, morphological, topographical and wettability studies. The X-ray diffraction (XRD) pattern showed the crystalline nature of selenium thin film with hexagonal crystal structure. The scanning electron microscopy (SEM) study displays selenium nanoparticles ranging from 20 to 475nm. A specific surface area of 30.5m(2)g(-1) is observed for selenium nanoparticles. The selenium nanoparticles hold mesopores in the range of 1.39nm, taking benefits of the good physicochemical stability and excellent porosity. Subsequently, the electrochemical properties of selenium thin films are deliberated by cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) techniques. The selenium thin film shows specific capacitance (Cs) of 21.98Fg(-1) with 91% electrochemical stability. PMID:26896773

  11. Syntheses of CuO nanostructures in ionic liquids

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A simple and efficient approach is developed to fabricate single-crystalline CuO nanostructures through an ionic liquid assisted one-step low-temperature solid-state route.Both nanoparticles(5 nm in size)and nanorods(5-10 nm in diameter and 50-100 nm in length)of monoclinic CuO were obtained. These synthesized CuO nanostructures were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),selected area electron diffraction(SAED),X-ray photoelectron spectros- copy(XPS),energy dispersive spectroscopy(EDS)and nitrogen adsorption analysis.The morpholo- gies of the nanostructures can be controlled by tuning the amount of NaOH and ionic liquids.The growth mechanism of CuO nanostructures is investigated.

  12. Syntheses of CuO nanostructures in ionic liquids

    Institute of Scientific and Technical Information of China (English)

    WANG Li; ZHAO Bin; YUAN ZhongYong; ZHANG XueJun; Wu QingDuan; CHANG LiXian; ZHENG WenJun

    2007-01-01

    A simple and efficient approach is developed to fabricate single-crystalline CuO nanostructures through an ionic liquid assisted one-step low-temperature solid-state route. Both nanoparticles (5 nm in size) and nanorods (5-10 nm in diameter and 50-100 nm in length) of monoclinic CuO were obtained. These synthesized CuO nanostructures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS) and nitrogen adsorption analysis. The morphologies of the nanostructures can be controlled by tuning the amount of NaOH and ionic liquids. The growth mechanism of CuO nanostructures is investigated.

  13. Electrochemically synthesized stretchable polypyrrole/fabric electrodes for supercapacitor

    International Nuclear Information System (INIS)

    Wearable electronics offer the combined advantages of both electronics and fabrics. Being an indispensable part of these electronics, lightweight, stretchable and wearable power sources are strongly demanded. Here we describe a daily-used cotton fabric coated with polypyrrole as electrode for stretchable supercapacitors. Polypyrrole was synthesized on the Au coated fabric via an electrochemical polymerization process with p-toluenesulfonic acid (p-TS) as dopant from acetonitrile solution. This material was characterized with FESEM, tensile stress, and studied as a supercapacitor electrode in 1.0 M NaCl. This conductive textile electrode can sustain up to 140% strain without electric failure. It delivers a high specific capacitance of 254.9 F g−1 at a scan rate of 10 mV s−1, and keeps almost unchanged at an applied strain (i.e. 30% and 50%) but with an improved cycling stability

  14. Liquid-phase synthesized mesoporous electrochemical supercapacitors of nickel hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Jinho; Park, Mira; Ham, Dukho; Mane, Rajaram S.; Han, Sung-Hwan [Inorganic Nano-Materials Laboratory, Department of Chemistry, Hanyang University, Sungdong-Ku, Haengdang-dong 17, Seoul 133-791 (Korea); Ogale, S.B. [Physical and Materials Chemsitry Division, National Chemical Laboratory, Dr. Homi Bhabha Road, Pashan, Pune 411008 (India)

    2008-06-01

    Electrochemical supercapacitive (ES) properties of liquid-phase synthesized mesoporous (pore size distribution centered {proportional_to}12 nm) and of 120 m{sup 2}/g surface area nickel hydroxide film electrodes onto tin-doped indium oxide substrate are discussed. The amounts of inner and outer charges are calculated to investigate the contribution of mesoporous structure on charge storage where relatively higher contribution of inner charge infers good ion diffusion into matrix of nickel hydroxide. Effect of different electrolytes, electrolyte concentrations, deposit mass and scan rates on the current-voltage profile in terms of the shape and enclosed area is investigated. Specific capacitance of {proportional_to}85 F/g at a constant current density of 0.03 A/g is obtained from the discharge curve. (author)

  15. Shape dependent heat transport through green synthesized gold nanofluids

    Science.gov (United States)

    John, Jisha; Thomas, Lincy; Kumar, B. Rajesh; Kurian, Achamma; George, Sajan D.

    2015-08-01

    Nanofluids hold promise as a more efficient coolant for thermoelectric devices. Despite the capability of tailoring the thermo physical properties of nanofluids, by tuning the particle parameters such as shape, size and concentration, the toxicity of chemicals used for the preparation of nanoparticles is a serious concern. Green synthesis of nanoparticles is emerging as an alternative to the conventional chemical and physical methods for the preparation of nanoparticles. In this work, the results of the preparation of gold nanoparticles using plant extracts as reducing agents are presented. The green synthesis route employed for the present study provides particles of similar size, but the shape of the particles is found to vary depending upon the source of the natural reducing agents. The thermal diffusivity values of the gold nanofluid measured using laser based dual beam thermal lens technique elucidate the role of shape and concentration of the green synthesized nanoparticles on the effective thermal diffusivity values of the nanofluids.

  16. Scalable syntheses of the BET bromodomain inhibitor JQ1

    Science.gov (United States)

    Syeda, Shameem Sultana; Jakkaraj, Sudhakar; Georg, Gunda I.

    2015-01-01

    We have developed methods involving the use of alternate, safer reagents for the scalable syntheses of the potent BET bromodomain inhibitor JQ1. A one-pot three step method, involving the conversion of a benzodiazepine to a thioamde using Lawesson’s reagent, followed by amidrazone formation and installation of the triazole moiety furnished JQ1. This method provides good yields and a facile purification process. For the synthesis of enantiomerically enriched (+)-JQ1, the highly toxic reagent diethyl chlorophosphate, used in a previous synthesis, was replaced with the safer reagent diphenyl chlorophosphate in the three-step one-pot triazole formation without effecting yields and enantiomeric purity of (+)-JQ1. PMID:26034331

  17. Polymer Films with Ion-Synthesized Cobalt and Iron Nanoparticles

    DEFF Research Database (Denmark)

    Popok, Vladimir

    2014-01-01

    The current paper presents an overview and analysis of data obtained on a few sets of polymer samples implanted by iron and cobalt. The low-energy (40 keV) implantations were carried out into polyimide and polyethyleneterephthalate with fluences between 2.5x10e16-1.5x10e17 cm-2. The samples were...... studied using several different methods to obtain information on structural and compositional changes as well as on the evolution of electrical and magnetic properties. High-fluence implantation led to significant carbonization of the polymers and formation of metal nanoparticles in the shallow layers....... Correlation between the structural changes, nucleation and percolation of the particles in relation to electronic properties of the composites are found, described and analysed. A few models explaining electrical and magnetic properties of the polymer films with synthesized metal nanoparticles are suggested....

  18. Rheological measurements in titania gels synthesized from reverse micelles

    Science.gov (United States)

    Romano, S. D.; Kurlat, D. H.

    2000-06-01

    TiO 2 sol and gel systems have been synthesized by hydrolysis of titanium butoxide in microemulsions W/O. Different systems compositions were prepared at constant Wo=[H 2O]/[AOT] and changing R=[H 2O]/[Ti(BuO) 4]. Experimental measurements show a progressive increase of the viscosity with time, characteristic of a sol-gel transition. The rheology of the transition was studied by following the behavior of viscoelastic parameters ( G', G″ and η*) as a function of time at different frequencies. The possibility to apply standard percolation theory was discussed. The application of two alternative growth models — either `fractal growth model' or `nearly linear growth model' — has been analysed.

  19. Synthesizing and salvaging NAD: lessons learned from Chlamydomonas reinhardtii.

    Directory of Open Access Journals (Sweden)

    Huawen Lin

    2010-09-01

    Full Text Available The essential coenzyme nicotinamide adenine dinucleotide (NAD+ plays important roles in metabolic reactions and cell regulation in all organisms. Bacteria, fungi, plants, and animals use different pathways to synthesize NAD+. Our molecular and genetic data demonstrate that in the unicellular green alga Chlamydomonas NAD+ is synthesized from aspartate (de novo synthesis, as in plants, or nicotinamide, as in mammals (salvage synthesis. The de novo pathway requires five different enzymes: L-aspartate oxidase (ASO, quinolinate synthetase (QS, quinolate phosphoribosyltransferase (QPT, nicotinate/nicotinamide mononucleotide adenylyltransferase (NMNAT, and NAD+ synthetase (NS. Sequence similarity searches, gene isolation and sequencing of mutant loci indicate that mutations in each enzyme result in a nicotinamide-requiring mutant phenotype in the previously isolated nic mutants. We rescued the mutant phenotype by the introduction of BAC DNA (nic2-1 and nic13-1 or plasmids with cloned genes (nic1-1 and nic15-1 into the mutants. NMNAT, which is also in the de novo pathway, and nicotinamide phosphoribosyltransferase (NAMPT constitute the nicotinamide-dependent salvage pathway. A mutation in NAMPT (npt1-1 has no obvious growth defect and is not nicotinamide-dependent. However, double mutant strains with the npt1-1 mutation and any of the nic mutations are inviable. When the de novo pathway is inactive, the salvage pathway is essential to Chlamydomonas for the synthesis of NAD+. A homolog of the human SIRT6-like gene, SRT2, is upregulated in the NS mutant, which shows a longer vegetative life span than wild-type cells. Our results suggest that Chlamydomonas is an excellent model system to study NAD+ metabolism and cell longevity.

  20. Syntheses and Chemosensory of Anthracene and Phenanthrene Bisimide Derivatives

    Science.gov (United States)

    Bogusz, Zachary A.

    2004-01-01

    As the present technology of biochemical weapons advances, it is essential for science to attempt to prepare our nation for such an occurrence. Various areas of current research are devoted to precautionary measures and potential antidotes for national security. A practical application of these precautions would be the development of a chemical capable of detecting harmful gas. The benefits of being capable to synthesis a chemical compound that would warn and identify potentially deadly gases would ensure a higher level of safety. The chemicals in question can be generalized as bisimide anthracene derivatives. The idea behind these compounds is that in the presence of certain nerve gases, the compound will actually fluoresce, giving an indication that there is a strong likelihood of the presence of a nerve gas and ensure the proper precautionary measures are taken. The fluorescence is due to the quenching of an electric proton transfer within the structure of the molecule. The system proves to be very unique on account of the fact that the fluorescence can be "turned off" by reducing the system. By utilizing the synthesis designed by Dr. Faysal Ilhan, four distinct compounds can be synthesized through photochemical reactions involving para- and ortho- diketones. The photochemistry involved is very modem and much research is being devoted to fully understanding the possibilities and alternative applications of such materials. and meta-nitro anthracene bisimide (ABI-NO2), the amine of each (ABI-NH2), a para- and meta-nitro phenanthrene bisimjde (PBI-NO2), and the amine of each (PBI-NH2). Upon synthesizing these distinct compounds, I must then purify and analyze them in order to obtain any relevant trends, behaviors, and characteristics. The chemical composition analyses that will be conducted are the procedures taken by Dr. Daniel Tyson on previous experiments. The results generated from the data will point further research in the correct direction and hopefully

  1. SO2 removal from flue gases using utility synthesized zeolites

    International Nuclear Information System (INIS)

    It is well known that natural and synthetic zeolites (molecular sieves) can adsorb gaseous SO2 from flue gas and do it more efficiently than lime based scrubbing materials. Unfortunately their cost ($500-$800 per ton) has deterred their use in this capacity. It is also known that zeolites are easy to synthesize from a variety of natural and man-made materials. The overall objective of the current work has been to evaluate the feasibility of having a utility synthesize its own zeolites, on-site, from fly ash and other recycled materials and then use these zeolites to adsorb SO2 from their flue gases. Work to date has shown that the efficiency of the capture process is related to the degree of crystallinity and the type of zeolite that forms in the samples. Normally, those samples cured at 150C contained a greater proportion of zeolite and as such were more SO2 adsorptive than their low-temperature counterparts. However, in order for the project to be successful, on site synthesis must remain an option, i.e. 100C synthesis. In light of this, the experimental focus now has two aspects. First, compositions of the starting materials are being altered by blending the current suite of fly ashes with other fly ashes, ground glass cullet and silica fume to promote the formation and growth of well crystallized and highly adsorptive zeolites. Second, greater degrees of reaction at significantly lower temperatures are being promote by ball milling the fly ash prior to use, by the use of more concentrated caustic solutions, and by the addition of zeolite seeds to the reactants. In all cases studies will focus on the effect of structure type and degree of conversion on SO2 adsorption. Future work will concentrate on the study of the effect of weathering on the suitability of converting fly ash into zeolites. This is an especially important study, considering the acres of fly ash now in storage throughout the country

  2. Phosphorylcholine substituted polyolefins: New syntheses, solution assemblies, and polymer vesicles

    Science.gov (United States)

    Kratz, Katrina A.

    This thesis describes the synthesis and applications of a new series of amphiphilic homopolymers and copolymers consisting of hydrophobic polyolefin backbone and hydrophilic phosphorylcholine (PC) pendant groups. These polymers are synthesized by ring opening metathesis polymerization (ROMP) of a novel PC- cyclooctene monomer, and copolymerization of various functionalized cyclooctene comonomers. Incorporation of different comonomers into the PC-polyolefin backbone affords copolymers with different functionalities, including crosslinkers, fluorophores, and other reactive groups, that tune the range of applications of these polymers, and their hydrophobic/hydrophilic balance. The amphiphilic nature of PC-polyolefins was exploited in oil-water interfacial assembly, providing robust polymer capsules to encapsulate and deliver nanoparticles to damaged regions of a substrate in a project termed `repair-and-go.' In repair-and-go, a flexible microcapsule filled with a solution of nanoparticles probes an imperfection-riddled substrate as it rolls over the surface. The thin capsule wall allows the nanoparticles to escape the capsules and enter into the cracks, driven in part by favorable interactions between the nanoparticle ligands and the cracked surface (i.e., hydrophobic-hydrophobic interactions). The capsules then continue their transport along the surface, filling more cracks and depositing particles into them. The amphiphilic nature of PC-polyolefins was also exploited in aqueous assembly, forming novel polymer vesicles in water. PC-polyolefin vesicles ranged in size from 50 nm to 30 µm. The mechanical properties of PC-polyolefin vesicles were measured by micropipette aspiration techniques, and found to be more robust than conventional liposomes or polymersomes prepared from block copolymers. PC-polyolefin vesicles have potential use in drug delivery; it was found that the cancer drug doxorubicin could be encapsulated efficiently in PC-polyolefin vesicles. In

  3. Template synthesized chitosan nano test tubes for drug delivery applications

    Science.gov (United States)

    Perry, Jillian L. Moulton

    There is tremendous current interest in developing nanoscale drug delivery vehicles. Though intensive efforts have focused on developing spherical drug delivery vehicles, cylindrically shaped vehicles such as nanotubes offer many advantages. Typically, nanotubes can carry a larger inner payload than nanoparticles of the same diameter. Also, we can prepare nanotubes in templates whose geometries can be controlled, in turn allowing precise control over the length and diameter of the tubes. In addition, template synthesized nanotubes can be differentially functionalized on the inner and outer surfaces. Furthermore, templates that are closed on one end can be used to fabricate nano test tubes (closed on one end). The geometry of these nano test tubes allows them to be easily filled with a payload, the open end sealed with a nanoparticle to protect the payload from leaking out, and then the exterior of the tube can be functionalized with a targeting moiety. In an effort to develop such a system, we explored the fabrication of chitosan nano test tubes. Defect-free, chitosan nano test tubes of uniform size were synthesized within the pores of a nanoporous alumina template membrane. While the nano test tubes remained within the template membrane, their inner cavities were filled with a model payload. The payload was then trapped inside the nano test tubes by sealing the open ends of the tubes with latex nanoparticle caps. For proof-of-principle studies, imine linkages were used to attach the caps to the nano test tubes. To create a self-disassembling system, disulfide chemistry was used to covalently cap the nano test tubes. Once removed from the template, the exterior of the nano test tubes were modified with a targeting moiety, allowing them to be targeted to pathological sites. We have also shown that the chitosan nano test tubes are biodegradable by two systems: enzymatic cleavage by lysozymes and disulfide cleavage of the crosslinker by reducing environments

  4. Three pharmaceuticals cocrystals of adefovir: Syntheses, structures and dissolution study

    Science.gov (United States)

    Zhang, Xiaoming; Sun, Fuxing; Zhang, Tingting; Jia, Jiangtao; Su, Hongmin; Wang, Chenhui; Zhu, Guangshan

    2015-11-01

    We report here three novel cocrystals, which are composed of adefovir as the API (Active Pharmaceutical Ingredient) with p-aminobenzoic acid (1, 2C8H12N5O4P·C7H6NO2·3H2O), 3,5-dihydroxybenzoic acid (2, C8H12N5O4P·C7H6O4·H2O) and 2,6-pyridinedicarboxlic acid (3, C8H12N5O4P·C7H5NO4) as CCFs (cocrystal formers) respectively by crystal engineering strategy. Their structures were characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD) analysis, thermogravimetric analyses (TGA), elemental analysis (EA) and infrared spectral analysis (IR). The analysis of single crystal X-ray diffraction demonstrate that cocrystal 1 and 2 form a strong hydrogen-bonded assembly through the phosphoric acids of API with water in the lattice and carboxylic acids of CCF respectively. Cocrystal 3 is formed in which the phosphoric acid groups of API are also held by the carboxylic acid groups of CCF. The PXRD results indicate their high purity of as-synthesized samples. The TGA, EA, IR and dissolution study of API and the cocrystals were also measured and discussed.

  5. Properties of radiation-synthesized polyvinylpyrrolidone/chitosan hydrogel blends

    International Nuclear Information System (INIS)

    Poly(vinylpyrrolidone) (PVP)-crosslinked chitosan hydrogels were prepared by gamma radiation at various doses; 1, 3 5, 7, 10, 15, 20, 25 and 30kGy. Gamma radiation was used as a crosslinking tool which requires no chemical initiator, no heating process and need no purification step on the end products obtained. The hydrogel formulations were composed of 6% chitosan with average molecular weight (Mw) = 48 800 g/mol and 14% PVP with Mw = 10 000 g/mol in 2% lactic acid. Physical properties of hydrogels such as gel fraction and swelling property at pH 5.5 and pH 7.0 as well as syneresis activity were determined. It was found that different radiation dose induces different effect on hydrogels’ network formed. Morphological study of hydrogels has been carried out by scanning electron microscope (SEM). From these preliminary evaluations, it can be concluded that gamma radiation is an effective tool for network development of hydrogels and it also induces enhancement on characteristics of hydrogels synthesized

  6. Properties of radiation-synthesized polyvinylpyrrolidone/chitosan hydrogel blends

    Science.gov (United States)

    Mahmud, Maznah; Daik, Rusli; Adam, Zainah

    2015-09-01

    Poly(vinylpyrrolidone) (PVP)-crosslinked chitosan hydrogels were prepared by gamma radiation at various doses; 1, 3 5, 7, 10, 15, 20, 25 and 30kGy. Gamma radiation was used as a crosslinking tool which requires no chemical initiator, no heating process and need no purification step on the end products obtained. The hydrogel formulations were composed of 6% chitosan with average molecular weight (Mw) = 48 800 g/mol and 14% PVP with Mw = 10 000 g/mol in 2% lactic acid. Physical properties of hydrogels such as gel fraction and swelling property at pH 5.5 and pH 7.0 as well as syneresis activity were determined. It was found that different radiation dose induces different effect on hydrogels' network formed. Morphological study of hydrogels has been carried out by scanning electron microscope (SEM). From these preliminary evaluations, it can be concluded that gamma radiation is an effective tool for network development of hydrogels and it also induces enhancement on characteristics of hydrogels synthesized.

  7. Microreactors-A Powerful Tool to Synthesize Peroxycarboxylic Esters.

    Science.gov (United States)

    Illg, Tobias; Knorr, Annett; Fritzsche, Lutz

    2015-01-01

    The synthesis of peroxycarboxylic esters, as one subgroup of organic peroxides, is characterized by a high thermal hazard potential regarding process safety. In case of failure in the production process, e.g., if the heat of reaction cannot be removed sufficiently fast, decomposition reactions can be triggered, and as a result, remarkable amounts of heat and gas can be released and can cause a high extent of damage. Multifarious technical and organizational measures are necessary to ensure the safe industrial production of peroxides. With the introduction of microreaction technology plenty of possibilities have been opened to carry out highly exothermic reactions in smaller volumes and with more efficient heat removal. In this paper we report the application of three different microstructured reactors, representing different mixing strategies, to synthesize two peroxymonocarboxylic esters, namely tert-butyl peroxypivalate and tert-butyl peroxy-2-ethylhexanoate. The following reactor types were considered: an orifice microreactor, a split and recombine microreactor and a capillary tube reactor in combination with ultrasonication. The efficiency of the two phase liquid/liquid reaction is expressed in comparison of conversion and selectivity. With microreaction technology a remarkable increase in space-time-yield, ranging from 12,500 kg·m(-3)·h(-1) to 414,000 kg·m(-3)·h(-1), is achieved. PMID:26703553

  8. Differential Transcriptome Analysis between Paulownia fortunei and Its Synthesized Autopolyploid

    Directory of Open Access Journals (Sweden)

    Xiaoshen Zhang

    2014-03-01

    Full Text Available Paulownia fortunei is an ecologically and economically important tree species that is widely used as timber and chemical pulp. Its autotetraploid, which carries a number of valuable traits, was successfully induced with colchicine. To identify differences in gene expression between P. fortunei and its synthesized autotetraploid, we performed transcriptome sequencing using an Illumina Genome Analyzer IIx (GAIIx. About 94.8 million reads were generated and assembled into 383,056 transcripts, including 18,984 transcripts with a complete open reading frame. A conducted Basic Local Alignment Search Tool (BLAST search indicated that 16,004 complete transcripts had significant hits in the National Center for Biotechnology Information (NCBI non-redundant database. The complete transcripts were given functional assignments using three public protein databases. One thousand one hundred fifty eight differentially expressed complete transcripts were screened through a digital abundance analysis, including transcripts involved in energy metabolism and epigenetic regulation. Finally, the expression levels of several transcripts were confirmed by quantitative real-time PCR. Our results suggested that polyploidization caused epigenetic-related changes, which subsequently resulted in gene expression variation between diploid and autotetraploid P. fortunei. This might be the main mechanism affected by the polyploidization. Our results represent an extensive survey of the P. fortunei transcriptome and will facilitate subsequent functional genomics research in P. fortunei. Moreover, the gene expression profiles of P. fortunei and its autopolyploid will provide a valuable resource for the study of polyploidization.

  9. Nanomechanical characterization of bioglass films synthesized by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Popa, A.C. [National Institute of Materials Physics, 077125 Magurele (Romania); Army Centre for Medical Research, 020012 Bucharest (Romania); Department of Cellular and Molecular Medicine, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest (Romania); Marques, V.M.F. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Stan, G.E., E-mail: george_stan@infim.ro [National Institute of Materials Physics, 077125 Magurele (Romania); Husanu, M.A.; Galca, A.C.; Ghica, C. [National Institute of Materials Physics, 077125 Magurele (Romania); Tulyaganov, D.U. [Turin Polytechnic University in Tashkent, 100174 Tashkent (Uzbekistan); Lemos, A.F.; Ferreira, J.M.F. [Department of Materials and Ceramics Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal)

    2014-02-28

    Bioactive glasses are osteoproductive-type inorganic materials possessing the highest indices of bioactivity in both bulk and thin film forms. The prerequisites for reliable implant-type coatings are both their biological and mechanical performances. Whilst the bioglass films' structural, chemical and biological properties have been studied extensively, information about their mechanical performance is scarce. Here, transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, nanoindentation and pull-out measurements were employed to assess the morphological, chemical, structural and mechanical properties of the bioglass films deposited onto Ti substrates by radio-frequency magnetron sputtering (RF-MS). The biological safety of the thin bioglass films was evaluated preliminarily in vitro by investigating the adherence, proliferation and cytotoxicity of fibroblast cells cultivated on their surface. Our study emphasize the versatility of RF-MS, showing how bioglass films' features such as composition, structure, bonding strength, hardness, elastic modulus and biological response can be conveniently adapted by tuning the RF-MS working conditions, and therefore demonstrating the unexplored potential of this deposition technique for preparing quality biomimetic glass coatings. - Highlights: • Adherent bioglass films were synthesized by RF-sputtering on titanium plates. • Different bonding configurations were obtained when tuning sputtering conditions. • Films' biological and mechanical responses vary with their structural arrangement. • Nanomechanical properties were enhanced by allowing O{sub 2} in the sputtering atmosphere.

  10. Evaluation of cytotoxicity of polypyrrole nanoparticles synthesized by oxidative polymerization

    International Nuclear Information System (INIS)

    Highlights: ► Polypyrrole nanoparticles synthesized by environmentally friendly polymerization at high concentrations are cytotoxic. ► Primary mouse embryonic fibroblast, mouse hepatoma and human T lymphocyte Jurkat cell lines were treated by Ppy nanoparticles. ► Polypyrrole nanoparticles at high concentrations inhibit cell proliferation. -- Abstract: Polypyrrole (Ppy) is known as biocompatible material, which is used in some diverse biomedical applications and seeming to be a very promising for advanced biotechnological applications. In order to increase our understanding about biocompatibility of Ppy, in this study pure Ppy nanoparticles (Ppy-NPs) of fixed size and morphology were prepared by one-step oxidative polymerization and their cyto-compatibility was evaluated. The impact of different concentration of Ppy nanoparticles on primary mouse embryonic fibroblasts (MEF), mouse hepatoma cell line (MH-22A), and human T lymphocyte Jurkat cell line was investigated. Cell morphology, viability/proliferation after the treatment by Ppy nanoparticles was evaluated. Obtained results showed that Ppy nanoparticles at low concentrations are biocompatible, while at high concentrations they became cytotoxic for Jurkat, MEF and MH-22A cells, and it was found that cytotoxic effect is dose-dependent

  11. Properties of radiation-synthesized polyvinylpyrrolidone/chitosan hydrogel blends

    Energy Technology Data Exchange (ETDEWEB)

    Mahmud, Maznah [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia 43600 Bangi, Selangor (Malaysia); Radiation Processing Technology Division, Malaysian Nuclear Agency, 43000 Kajang, Selangor (Malaysia); Daik, Rusli [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia 43600 Bangi, Selangor (Malaysia); Adam, Zainah [Radiation Processing Technology Division, Malaysian Nuclear Agency, 43000 Kajang, Selangor (Malaysia)

    2015-09-25

    Poly(vinylpyrrolidone) (PVP)-crosslinked chitosan hydrogels were prepared by gamma radiation at various doses; 1, 3 5, 7, 10, 15, 20, 25 and 30kGy. Gamma radiation was used as a crosslinking tool which requires no chemical initiator, no heating process and need no purification step on the end products obtained. The hydrogel formulations were composed of 6% chitosan with average molecular weight (Mw) = 48 800 g/mol and 14% PVP with Mw = 10 000 g/mol in 2% lactic acid. Physical properties of hydrogels such as gel fraction and swelling property at pH 5.5 and pH 7.0 as well as syneresis activity were determined. It was found that different radiation dose induces different effect on hydrogels’ network formed. Morphological study of hydrogels has been carried out by scanning electron microscope (SEM). From these preliminary evaluations, it can be concluded that gamma radiation is an effective tool for network development of hydrogels and it also induces enhancement on characteristics of hydrogels synthesized.

  12. Radio-synthesized polyacrylamide hydrogels for proteins release

    International Nuclear Information System (INIS)

    The use of hydrogels for biomedical purposes has been extensively investigated. Pharmaceutical proteins correspond to highly active substances which may be applied for distinct purposes. This work concerns the development of radio-synthesized hydrogel for protein release, using papain and bovine serum albumin as model proteins. The polymer was solubilized (1% w/v) in water and lyophilized. The proteins were incorporated into the lyophilized polymer and the hydrogels were produced by simultaneous crosslinking and sterilization using γ-radiation under frozen conditions. The produced systems were characterized in terms of swelling degree, gel fraction, crosslinking density and evaluated according to protein release, bioactivity and cytotoxicity. The hydrogels developed presented different properties as a function of polymer concentration and the optimized results were found for the samples containing 4–5% (w/v) polyacrylamide. Protein release was controlled by the electrostatic affinity of acrylic moieties and proteins. This selection was based on the release of the proteins during the experiment period (up to 50 h), maintenance of enzyme activity and the nanostructure developed. The system was suitable for protein loading and release and according to the cytotoxic assay it was also adequate for biomedical purposes, however this method was not able to generate a matrix with controlled pore sizes. Highlights: • Method for synthesis of polyacrylamide (copolymer) hydrogels using γ-irradiation. • Polyacrylamide hydrogels suitable for protein loading and release. • Controlled release of proteins and bioactivity maintenance. • Noncytotoxic profile observed for these protein containing hydrogels

  13. Silver-based biohybrids "green" synthesized from Chelidonium majus L.

    Science.gov (United States)

    Barbinta-Patrascu, Marcela Elisabeta; Badea, Nicoleta; Ungureanu, Camelia; Constantin, Marioara; Pirvu, Cristian; Rau, Ileana

    2016-06-01

    This paper describes an original bio-design of organic/inorganic hybrid architectures containing biomimetic membranes and celandine-nanoAg for different bioapplications. A simple, time efficient, low-cost and ecofriendly bottom-up procedure was used to build for the first time, celandine/nanoAg-based hybrids. Dipalmitoyl phosphatidylcholine bio-inspired lipid bilayers were obtained by thin film hydration method. Chlorophyll a inserted into these liposomes was used as a spectral marker to detect the changes occurred in the artificial membranes. For the first time, silver nanoparticles were eco-synthesized using an aqueous extract of celandine (Chelidonium majus L.). The physical stability of the samples was evaluated in terms of zeta potential. Chlorophyll a photonic properties (based on UV-Vis absorption and emission spectra) were used to monitor the synthesis of silver nanoparticles and of bio-based hybrids. The size of samples was monitored by Dynamic Light Scattering measurements and the morphological aspects were provided by Atomic Force Microscopy analysis. The obtained silver-based biohybrids exhibited high antioxidant activity (98.48%) and strong antimicrobial properties against Escherichia coli ATCC 8738 (offering an inhibition zone of 51 mm diameter) and presented good physical stability (zeta potential reached the value of -30.7 mV) as compared to phyto-nanoAg alone.

  14. Conceptualizing and measuring energy security: A synthesized approach

    International Nuclear Information System (INIS)

    This article provides a synthesized, workable framework for analyzing national energy security policies and performance. Drawn from research interviews, survey results, a focused workshop, and an extensive literature review, this article proposes that energy security ought to be comprised of five dimensions related to availability, affordability, technology development, sustainability, and regulation. We then break these five dimensions down into 20 components related to security of supply and production, dependency, and diversification for availability; price stability, access and equity, decentralization, and low prices for affordability; innovation and research, safety and reliability, resilience, energy efficiency, and investment for technology development; land use, water, climate change, and air pollution for sustainability; and governance, trade, competition, and knowledge for sound regulation. Further still, our synthesis lists 320 simple indicators and 52 complex indicators that policymakers and scholars can use to analyze, measure, track, and compare national performance on energy security. The article concludes by offering implications for energy policy more broadly. -- Highlights: → Energy security should consist of five dimensions related to availability, affordability, technology development, sustainability, and regulation. → The dimensions of energy security can be broken down into 20 components. → These components can be distilled into 320 simple indicators and 52 complex indicators.

  15. beta-glucosidase catalyzed syntheses of pyridoxine glycosides.

    Science.gov (United States)

    Charles, Rajachristu Einstein; Divakar, Soundar

    2009-01-01

    Enzymatic syntheses of pyridoxine glycosides were carried out in di-isopropyl ether organic medium using beta-glucosidase isolated from sweet almond. Optimum conditions determined for the reaction with D-glucose were 40% (w/w D-glucose) beta-glucosidase at 0.18 mM (1.8 ml) of pH 5 acetate buffer over a 72 h incubation period. Of 11 carbohydrates employed, beta-glucosidase gave 7-O-(alpha-D-glucopyranosyl)pyridoxine 5a, 7-O-(beta-D-glucopyranosyl)pyridoxine 5b, 6-O-(alpha-D-glucopyranosyl)pyridoxine 5c, 7-O-(alpha-D-galactopyranosyl)pyridoxine 6a, 7-O-(beta-D-galactopyranosyl)pyridoxine 6b, 6-O-(alpha-D-galactopyranosyl)pyridoxine 6c, 7-O-(alpha-D-mannopyranosyl)pyridoxine 7a, 7-O-(beta-D-mannopyranosyl)pyridoxine 7b, and 6-O-(alpha-D-mannopyranosyl)pyridoxine 7c in yields ranging from 23 to 40%. PMID:19129657

  16. Syntheses of alpha-tocopheryl glycosides by glucosidases.

    Science.gov (United States)

    Ponrasu, Thangavel; Charles, Rajachristu Einstein; Sivakumar, Ramaiah; Divakar, Soundar

    2008-08-01

    Enzymatic syntheses of water-soluble alpha-tocopheryl glycosides were carried out in di-isopropyl ether using amyloglucosidase from Rhizopus mold or beta-glucosidase isolated from sweet almond. Optimum conditions for the amyloglucosidase were: alpha-tocopherol 0.5 mmol, D-glucose 0.5 mmol, 400 activity unit (AU) amyloglucosidase, 0.2 mM pH 7 phosphate buffer and 72 h; and for the beta-glucosidase: alpha-tocopherol 0.5 mmol, D: -glucose 0.5 mmol, 110 AU beta-glucosidase, 0.1 mM pH 6 phosphate buffer and 72 h. Out of 11 carbohydrates employed, amyloglucosidase reacted only with D-glucose to give 50% of 6-O-(alpha-D-glucopyranosyl)alpha-tocopherol. However, the beta-glucosidase gave 6-O-(beta-D-glucopyranosyl)alpha-tocopherol, 6-O-(alpha-D-galactopyranosyl)alpha-tocopherol, 6-O-(beta-D-galactopyranosyl)alpha-tocopherol, 6-O-(alpha-D-mannopyranosyl)alpha-tocopherol and 6-O-(beta-D-mannopyranosyl)alpha-tocopherol in yields ranging from 10-25%. Water solubility of 6-O-(alpha-D-glucopyranosyl)alpha-tocopherol was 26 g/l at 25 degrees C. alpha-Tocopheryl glycosides showed antioxidant activities with IC(50) values from 0.5 to 1 mM and angiotensin-converting enzyme (ACE) inhibitory activity with IC(50) values from 1.3 to 2.6 mM. PMID:18368294

  17. High-performance Ni3Al synthesized from composite powders

    Science.gov (United States)

    Chiou, Wen-Chih; Hu, Chen-Ti

    1994-05-01

    Specimens of Ni3Al + B of high density (>99.3 Pct RD) and relatively large dimension have been synthesized from composite powders through processes of replacing plating and electroless Ni-B plating on Al powder, sintering, and thermal-mechanical treatment. The uniformly coated Ni layer over fine Al or Ni core particles constituting these coating/core composite powders has advantages such as better resistance to oxidation relative to pure Al powder, a greater green density as a compacted powder than prealloyed powder, the possibility of atomically added B to the material by careful choice of a suitable plating solution, and avoidance of the expensive powder metallurgy (PM) equipment such as a hot isostatic press (HIP), hot press (HP), etc. The final Ni3Al + B product is made from Ni-B-Al and Ni-B-Ni mixed composite powders by means of traditional PM processes such as compacting, sintering, rolling, and annealing, and therefore, the dimensions of the product are not constrained by the capacity of an HIP or HP. The properties of Ni3Al composite powder metallurgy (CPM) specimens tested at room temperature have been obtained, and comparison with previous reports is conducted. A tensile elongation of about 16 Pct at room temperature was attained.

  18. A synthesized windfield model for tornado missile transport

    International Nuclear Information System (INIS)

    A tornado windfield model has been developed for use in a probabilistic assessment of the tornado missile hazard to nuclear power plants. Tornado flow characteristics have been identified which are significant in terms of missile transport phenomena. In order to account for both modeling uncertainty and the natural variability observed among tornadoes, several random variables are specified in the model, including: tornado intensity, path width, translational speed, radius to maximum tangential velocity, ratio of radial-to-tangential wind speed, vertical variation of core size, and boundary layer thickness. Considering the lack of agreement regarding detailed tornado dynamics as well as the difficulty in establishing a priori conservative flow characteristics for missile transport, the windfield model was synthesized from theoretical, observational, and probabilistic considerations. A significant aspect of the model is that the parameters can be adjusted to make the intensity size and velocity variables consistent with the tornado path width boundary specification. The modelling considerations are discussed, the windfield model and calculational procedure presented, sample windfield component velocity profiles illustrated, and missile velocity statistics given for a simulation case study involving several thousand missile histories. (Auth.)

  19. Morphology and electrical properties of template-synthesized polypyrrole nanocylinders

    Science.gov (United States)

    Mativetsky, J. M.; Datars, W. R.

    2002-11-01

    Polypyrrole nanocylinders were fabricated by chemically synthesizing polypyrrole within the pores of nanoporous polycarbonate particle track-etched membranes. The morphology of the nanostructures was characterized by transmission electron microscopy and scanning electron microscopy. The nanocylinders were observed to be cigar-shaped, with the diameter at the center being up to 2.5 times the diameter at the ends. The electrical conductivity of the nanocylinders was measured by leaving the nanocylinders embedded in the insulating template membrane and measuring the trans-membrane resistance. The cigar-like shape of the nanocylinders was taken into account in calculating the conductivity. Contrary to previous reports, the smallest diameter nanocylinders exhibited a slightly lower conductivity relative to the larger diameter nanocylinders. The temperature dependence of the resistance and magnetoresistance was in accordance with Mott variable range hopping at temperatures above 5±1 K and Efros-Shklovskii variable range hopping at temperatures below 5±1 K. Based on the measurements in the Mott regime, the localization length, the density of states at the Fermi energy, and the temperature dependence of the average hopping distance were calculated.

  20. Syntheses of Binuclear Copper(Ⅰ)Complexes Containing Benzimidazole

    Institute of Scientific and Technical Information of China (English)

    LIU Ying-Fan; ZHAO Dong; GUO Li-Bing; ZHENG Xin; SUN Yu-An

    2005-01-01

    A binuclear copper(Ⅰ) complex [Cu2(dppm)2(C7H6N2)2](NO3)2 (C7H6N2 = benzimidazole, dppm = Ph2PCH2PPh2) has been synthesized and characterized by X-ray crystallography.The crystal belongs to monoclinic, space group C2/c with a = 14.167(3), b = 21.209(4), c =20.680(4) A, β = 103.93(3)°, C32H28CuN3O3P2, Mr = 628.05, Z = 8,μ = 0.868 mm-1, V = 6031 (2)(。A)3,F(000) = 2592, Dc= 1.383 g/cm3, R = 0.0593 and wR = 0.1736.A total of 5297 independent reflec tions were collected, of which 3503 were observed with I > 2σ(I).The central copper atom is tri-coordinated by phosphorus atoms from bridging dppm and nitrogen atom from benzimidazole.In the coordination sphere, the bond lengths of Cu-P(1) and Cu-P(2) are 2.2607(17) and 2.2503(16)(。A),respectively and the P-Cu-P bond angle is 127.26(6)°.

  1. Carbon nanofibers synthesized by pyrolysis of chloroform and ethanol mixture

    International Nuclear Information System (INIS)

    Platelet graphite nanofibers (PGNFs) and turbostratic carbon nanofibers (TSCNFs) were synthesized by the pyrolysis of 3 and 10 vol% chloroform in ethanol, respectively, in the presence of Ni catalyst at 700 °C. Auger electron spectrometry analysis reveals that the participation of chloroform in the synthesis led to Ni–Cl bonding on the surface of the catalysts, resulting in a relatively poor crystalline layer and a coarse surface. Furthermore, the Ni–Cl compound affected the melting point and mobility of Ni, changing the morphology and geometrical shape of Ni particles. A low amount of chlorine in the catalyst led to the formation of smaller catalyst particles with a flat surface, resulting in graphene nanosheets stacked perpendicular to the fiber axis, which became PGNFs. In contrast, a high amount of chlorine in the catalyst led to the aggregation of the catalyst and thus the formation of large catalyst particles with a rough surface, resulting in the random stacking of graphene nanosheets, which became TSCNFs. The participation of chlorine was found to be important in the synthesis of the PGNFs and TSCNFs. - Graphical abstract: Display Omitted - Highlights: • The morphology of CNFs changed while different amount of CHCl3 presented. • The interaction of Ni and Cl changed the geometry and morphology of catalysts. • The structure of CNFs formed attributed to the surface morphology of catalysts. • PGNFs and TSCNFs were perpendicular and random stacking of graphene

  2. Perfluorocyclobutyl-containing Amphiphilic Block Copolymers Synthesized by RAFT Polymerization

    Institute of Scientific and Technical Information of China (English)

    LI, Yongjun; ZHANG, Sen; FENG, Chun; ZHANG, Yaqin; LI, Qingnuan; LI, Wenxin; HUANG, Xiaoyu

    2009-01-01

    Amphiphilic block copolymers containing hydrophobic perfluorocyclobutyl-based (PFCB) polyacrylate and hydrophilic poly(ethylene glycol) (PEG) segments were prepared via reversible addition-fragmentation chain transfer (RAP-T) polymerization. The PFCB-containing acrylate monomer, p-(2-(p-tolyloxy)perfluorocyclobutoxy)phenyl acrylate, was first synthesized from commercially available compounds in good yields, and this kind of acrylate monomer can be homopolymerized by free radical polymerization or RAFT polymerization. Kinetic study showed the 2,2'-azobis(isobutyronitrile) (AIBN) initiated and cumyl dithiobenzoate (CDB) mediated RAFT polymerization was in a living fashion, as suggested by the fact that the number-average molecular weights (M_n) increased linearly with the conversions of the monomer, while the polydispersity indices kept less than 1.10. The block polymers with narrow molecular weight distributions (M_w/M_n≤1.21) were prepared through RAFT polymerization using PEG monomethyl ether capped with 4-cyanopentanoic acid dithiobenzoate end group as the macro chain transfer agent (mPEG-CTA). The length of the hydrophobic segment can be tuned by the feed ratio of the PFCB-based acrylate monomer and the extending of the polymerization time. The micellization behavior of the block copolymers in aqueous media was investigated by the fluorescence probe technique.

  3. Making the Bread: Insights from Newly Synthesized Allohexaploid Wheat.

    Science.gov (United States)

    Li, Ai-li; Geng, Shuai-Feng; Zhang, Lian-quan; Liu, Deng-cai; Mao, Long

    2015-06-01

    Bread wheat (or common wheat, Triticum aestivum) is an allohexaploid (AABBDD, 2n = 6x = 42) that arose by hybridization between a cultivated tetraploid wheat T. turgidum (AABB, 2n = 4x = 28) and the wild goatgrass Aegilops tauschii (DD, 2n = 2x = 14). Polyploidization provided niches for rigorous genome modification at cytogenetic, genetic, and epigenetic levels, rendering a broader spread than its progenitors. This review summarizes the latest advances in understanding gene regulation mechanisms in newly synthesized allohexaploid wheat and possible correlation with polyploid growth vigor and adaptation. Cytogenetic studies reveal persistent association of whole-chromosome aneuploidy with nascent allopolyploids, in contrast to the genetic stability in common wheat. Transcriptome analysis of the euploid wheat shows that small RNAs are driving forces for homoeo-allele expression regulation via genetic and epigenetic mechanisms. The ensuing non-additively expressed genes and those with expression level dominance to the respective progenitor may play distinct functions in growth vigor and adaptation in nascent allohexaploid wheat. Further genetic diploidization of allohexaploid wheat is not random. Regional asymmetrical gene distribution, rather than subgenome dominance, is observed in both synthetic and natural allohexaploid wheats. The combinatorial effects of diverged genomes, subsequent selection of specific gene categories, and subgenome-specific traits are essential for the successful establishment of common wheat. PMID:25747845

  4. Characterization of carbon cryogels synthesized by sol-gel polycondensation

    Directory of Open Access Journals (Sweden)

    BILJANA BABIC

    2005-02-01

    Full Text Available Resorcinol-formaldehyde (RF cryogels were synthesized by the sol-gel polycondensation of resorcinol (R with formaldehyde (F and freeze-drying was carried out with t-butanol. Carbon cryogels were obtained by pyrolyzing RF cryogels in an inert atmosphere. Characterization by nitrogen adsorption showed that the carbon cryogels were micro and mesoporous materials with high specific surface areas (SBET ~ 550 m2/g. Cyclic voltammetry experiments at various scan rates (2 to 200 mV s-1 were performed to study the electrical double-layer charging of carbon cryogel electrodes in 0.5 mol dm-3 HClO4 solution. It has been demonstrated that it is possible to sub-divide the total specific capacitance into the mesoporous and the microporous specific capacitance by analyzing the linear dependence of the charge (q on the reciprocal of the square root of the potential scan rate (v-1/2, and the linear dependence of the reciprocal charge (1/q on the square root of the potential scan rate (v-1/2. The specific capacitance was found to be constant over a wide range of sample weight (12.5 to 50.0 mg and a very promising specific capacitance value of 150 F/g, was found for this material operating in an acidic 0.5 mol dm-3 HClO4 solution at room temperature.

  5. Antibacterial effect of bismuth subsalicylate nanoparticles synthesized by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Flores-Castañeda, Mariela [Instituto Nacional de Investigaciones Nucleares (Mexico); Vega-Jiménez, Alejandro L., E-mail: argelia.almaguer@mac.com; Almaguer-Flores, Argelia [Universidad Nacional Autónoma de México, Facultad de Odontología, DEPeI, I (Mexico); Camps, Enrique; Pérez, Mario [Instituto Nacional de Investigaciones Nucleares (Mexico); Silva-Bermudez, Phaedra [Instituto Nacional de Rehabilitación, Unidad de Ingeniería de Tejidos, Terapia Celular y Medicina Regenerativa (Mexico); Berea, Edgardo [FarmaQuimia SA de CV. (Mexico); Rodil, Sandra E. [Universidad Nacional Autónoma de México, Instituto de Investigaciones en Materiales (Mexico)

    2015-11-15

    The antimicrobial properties of bismuth subsalicylate (BSS) nanoparticles against four opportunistic pathogens; E. coli, P. aeruginosa, S. aureus, and S. epidermidis were determined. BSS nanoparticles were synthesized by pulse laser ablation of a solid target in distilled water under different conditions. The nanoparticles were characterized using high-resolution transmission electron microscopy and absorption spectra and small angle X-ray scattering. The analysis shows that the colloids maintained the BSS structure and presented average particle size between 20 and 60 nm, while the concentration ranges from 95 to 195 mg/L. The antibacterial effect was reported as the inhibition ratio of the bacterial growth after 24 h and the cell viability was measured using the XTT assay. The results showed that the inhibition ratio of E. coli and S. epidermidis was dependant on the NPs size and/or concentration, meanwhile P. aeruginosa and S. aureus were more sensitive to the BSS nanoparticles independently of both the size and the concentration. In general, the BSS colloids with average particle size of 20 nm were the most effective, attaining inhibition ratios >80 %, similar or larger than those obtained with the antibiotic used as control. The results suggest that the BSS colloids could be used as effective antibacterial agents with potential applications in the medical area.

  6. Evaluation of cytotoxicity of polypyrrole nanoparticles synthesized by oxidative polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Vaitkuviene, Aida [Department of Physical Chemistry, Faculty of Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius (Lithuania); Department of Stem Cell Biology, State Research Institute Center for Innovative Medicine, Zygimantu 9, LT-01102 Vilnius (Lithuania); Kaseta, Vytautas [Department of Stem Cell Biology, State Research Institute Center for Innovative Medicine, Zygimantu 9, LT-01102 Vilnius (Lithuania); Voronovic, Jaroslav [Department of Physical Chemistry, Faculty of Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius (Lithuania); Ramanauskaite, Giedre; Biziuleviciene, Gene [Department of Stem Cell Biology, State Research Institute Center for Innovative Medicine, Zygimantu 9, LT-01102 Vilnius (Lithuania); Ramanaviciene, Almira [NanoTechnas–Center of Nanotechnology and Material Science at Department of Analytical and Environmental Chemistry, Faculty of Chemistry, Vilnius University, Naugarduko 24, 03225 Vilnius (Lithuania); Ramanavicius, Arunas, E-mail: Arunas.Ramanavicius@chf.vu.lt [Department of Physical Chemistry, Faculty of Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius (Lithuania); Laboratory of BioNanoTechnology, Department of Materials Science and Electronics, Institute of Semiconductor Physics, State Scientific Research Institute Centre for Physical Sciences and Technology, A. Gostauto 11, LT-01108 Vilnius (Lithuania)

    2013-04-15

    Highlights: ► Polypyrrole nanoparticles synthesized by environmentally friendly polymerization at high concentrations are cytotoxic. ► Primary mouse embryonic fibroblast, mouse hepatoma and human T lymphocyte Jurkat cell lines were treated by Ppy nanoparticles. ► Polypyrrole nanoparticles at high concentrations inhibit cell proliferation. -- Abstract: Polypyrrole (Ppy) is known as biocompatible material, which is used in some diverse biomedical applications and seeming to be a very promising for advanced biotechnological applications. In order to increase our understanding about biocompatibility of Ppy, in this study pure Ppy nanoparticles (Ppy-NPs) of fixed size and morphology were prepared by one-step oxidative polymerization and their cyto-compatibility was evaluated. The impact of different concentration of Ppy nanoparticles on primary mouse embryonic fibroblasts (MEF), mouse hepatoma cell line (MH-22A), and human T lymphocyte Jurkat cell line was investigated. Cell morphology, viability/proliferation after the treatment by Ppy nanoparticles was evaluated. Obtained results showed that Ppy nanoparticles at low concentrations are biocompatible, while at high concentrations they became cytotoxic for Jurkat, MEF and MH-22A cells, and it was found that cytotoxic effect is dose-dependent.

  7. Of Syntheses and Surprises:Toward a Critical Integral Theory

    Directory of Open Access Journals (Sweden)

    Daniel Gustav Anderson

    2006-12-01

    Full Text Available The central concern of this article is how the search for formal structures with universal values functions ideologically, addressing Zizek’s claim that East-West syntheses may represent the dominant ideology par excellance of global capitalism. To this end, the article offers a Foucaultian genealogy of Integral theory, tracing its origins to the cultural and subjective contingencies of the British Empire, primarily in the work of Integral theory’s foundational thinker, Aurobindo Ghose. The article poses a primary critique of synthesis and evolution as mythological keys to Ultimate Reality which suggests that Zizek’s critique may have some validity, and offers the potential for a “critical integral theory” as an alternative. Situated in Deleuze and Guattari’s concept of becoming, and represented in the ideas and practices of a constellation of thinkers inclusive of Gurdjieff, Benjamin, and Trungpa, the article’s view of integration supports radical democracy as presented in the writings of Laclau and Mouffe as a model outcome for social and personal transformational practices.

  8. Multifunctional Catalysts to Synthesize and Utilize Energy Carriers

    Energy Technology Data Exchange (ETDEWEB)

    Lercher, Johannes A.; Appel, Aaron M.; Autrey, Thomas; Bullock, R. Morris; Camaioni, Donald M.; Cho, Herman M.; Dixon, David A.; Dohnalek, Zdenek; Gao, Feng; Glezakou, Vassiliki Alexandra; Henderson, Michael A.; Hu, Jian Z.; Iglesia, Enrique; Karkamkar, Abhijeet J.; Kay, Bruce D.; Kimmel, Gregory A.; Linehan, John C.; Liu, Jun; Lyubinetsky, Igor; Mei, Donghai; Peden, Charles HF; Rousseau, Roger J.; Schenter, Gregory K.; Shaw, Wendy J.; Szanyi, Janos; Wang, Huamin; Wang, Yong; Weber, Robert S.

    2014-06-23

    The central role and critical importance of catalysis in a future based on sustainability, together with the insight that developments have to be knowledge-based have motivated significant efforts to better understand catalyzed processes and to develop new catalytic routes from this knowledge. Overall, three main energy carriers are used worldwide, carbon (and hydrocarbons), hydrogen, and electrons. Conventionally, the stored energy is accessed by oxidizing carbon and hydrogen, forming O-H and C-O bonds and performing work with the produced heat or electricity. Conversely, to synthesize energy carriers sustainably, it is consequently required to reverse the direction, i.e., to break C-O and O-H bonds and form C-C, C-H and H-H bonds. To address these challenges, PNNL’s BES-sponsored program comprises three thrust areas with subtasks, focusing on the fundamentals of biomass conversion processes, direct and indirect CO2 reduction, and on elementary studies aimed at generating and using H2. Multi-functionality, i.e., the simultaneous interaction of more than one catalytically active site with the substrate is the key to achieving the atom and energy efficiency in individual steps. The combination of several types of these sites with carefully selected energetics and rate constants is used to generate complex catalysts able to enhance the rates of multistep processes. This short report summarizes recent results obtained in this BES-funded program.

  9. Microreactors—A Powerful Tool to Synthesize Peroxycarboxylic Esters

    Directory of Open Access Journals (Sweden)

    Tobias Illg

    2015-12-01

    Full Text Available The synthesis of peroxycarboxylic esters, as one subgroup of organic peroxides, is characterized by a high thermal hazard potential regarding process safety. In case of failure in the production process, e.g., if the heat of reaction cannot be removed sufficiently fast, decomposition reactions can be triggered, and as a result, remarkable amounts of heat and gas can be released and can cause a high extent of damage. Multifarious technical and organizational measures are necessary to ensure the safe industrial production of peroxides. With the introduction of microreaction technology plenty of possibilities have been opened to carry out highly exothermic reactions in smaller volumes and with more efficient heat removal. In this paper we report the application of three different microstructured reactors, representing different mixing strategies, to synthesize two peroxymonocarboxylic esters, namely tert-butyl peroxypivalate and tert-butyl peroxy-2-ethylhexanoate. The following reactor types were considered: an orifice microreactor, a split and recombine microreactor and a capillary tube reactor in combination with ultrasonication. The efficiency of the two phase liquid/liquid reaction is expressed in comparison of conversion and selectivity. With microreaction technology a remarkable increase in space-time-yield, ranging from 12,500 kg·m−3·h−1 to 414,000 kg·m−3·h−1, is achieved.

  10. Design, syntheses, and conformational study of angiogenesis inhibitors

    International Nuclear Information System (INIS)

    Since anti-angiogensis could lead to the suppression of tumor growth, angiogenesis inhibitors have received particular attention for their therapeutic potential. In this study, two angiogenic inhibitors using the bioactive sequence from the kringle 5, AK1(KLYDY), AK2(KLWDF) were designed and synthesized. We have investigated their solution structures using NMR spectroscopy and their activities as angiogenesis inhibitors. AK2 has an intramolecular hydrogen bond between the side chain amino proton of Lys1 and the carboxy1 oxygen of Asp4 with a N···O distance of 3.27 A, while AK1 shows more flexible structures than AK2. Indole ring in Trp is much bigger than the phenyl ring in Tyr and may have good face-to-edge interaction enforcing more rigid and constrained conformational features of AK2. Because of this relatively stable structure, Trp3 in AK2 may have better hydrophobic interaction with Phe5 than Tyr3 in AK1 if two adjacent aromatic groups are located in hydrophobic pocket of receptor. Since AK2 shows the similar anti-angiogenic activities to AK1, we are also able to confirm that the activity of AK1 is irrelevant to the Tyr phosphorylation. More rigid drug with higher activities can be provided by the mimetic approaches. For the further development of the angiogenesis inhibitors, these conformational studies on our lead peptides will be helpful in design of peptidomimetics

  11. TOP as ligand and solvent to synthesize silver telluride nanosheets

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shutang, E-mail: shutang.chen@uconn.edu [Division of Energy Systems Research, Ajou University, Suwon 443-749 (Korea, Republic of); Department of Chemistry, University of Connecticut, Storrs 06269 (United States); Lee, Soonil, E-mail: soonil@ajou.ac.kr [Division of Energy Systems Research, Ajou University, Suwon 443-749 (Korea, Republic of)

    2015-11-15

    Highlights: • Silver telluride nanosheets were prepared through one-pot synthetic strategy. • TOP as both ligand and solvent favors silver telluride nanosheets growth. • The I–V curve of an Ag{sub 2}Te-nanosheet film indicates that as-prepared Ag{sub 2}Te nanosheets have good electric conductivity. - Abstract: Ag{sub 2}Te nanosheets are synthesized by a simple one-pot route using trioctylphosphine (TOP) as both solvent and stabilizer. Various controlling parameters were examined, such as molar ratios of AgNO{sub 3} to tellurium powder, reaction temperature and time, and precursor concentration. The morphology and composition of the products were characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy. On the basis of a series of synthesis and characterizations, the formation mechanism of the Ag{sub 2}Te nanosheets are discussed. The I–V curve of an Ag{sub 2}Te-nan osheet film indicates that as-prepared Ag{sub 2}Te nanosheets have good electric conductivity.

  12. Synthesizing complex movement fragment representations from motor cortical ensembles

    Science.gov (United States)

    Hatsopoulos, Nicholas G.; Amit, Yali

    2011-01-01

    We have previously shown that the responses of primary motor cortical neurons are more accurately predicted if one assumes that individual neurons encode temporally-extensive movement fragments or preferred trajectories instead of static movement parameters (Hatsopoulos et al., 2007). Building on these findings, we examine here how these preferred trajectories can be combined to generate a rich variety of preferred movement trajectories when neurons fire simultaneously. Specifically, we used a generalized linear model to fit each neuron’s spike rate to an exponential function of the inner product between the actual movement trajectory and the preferred trajectory; then, assuming conditional independence, when two neurons fire simultaneously their spiking probabilities multiply implying that their preferred trajectories add. We used a similar exponential model to fit the probability of simultaneous firing and found that the majority of neuron pairs did combine their preferred trajectories using a simple additive rule. Moreover, a minority of neuron pairs that engaged in significant synchronization combined their preferred trajectories through a small scaling adjustment to the additive rule in the exponent, while preserving the predicted trajectory representation from the additive rule. These results suggest that complex movement representations can be synthesized in simultaneously firing neuronal ensembles by adding the trajectory representations of the constituents in the ensemble. PMID:21939762

  13. Characterization of silver nanoparticles synthesized on titanium dioxide fine particles

    Energy Technology Data Exchange (ETDEWEB)

    Nino-Martinez, N [Facultad de Ciencias, UASLP, Alvaro Obregon 64, CP 78000, San Luis PotosI, SLP (Mexico); Martinez-Castanon, G A [Maestria en Ciencias Odontologicas, Facultad de EstomatologIa, UASLP, Avenida Manuel Nava 2, Zona Universitaria, San Luis PotosI, SLP (Mexico); Aragon-Pina, A [Instituto de Metalurgia, Facultad de IngenierIa, UASLP, Alvaro Obregon 64, CP 78000, San Luis PotosI, SLP (Mexico); Martinez-Gutierrez, F [Facultad de Ciencias Quimicas, UASLP, Alvaro Obregon 64, CP 78000, San Luis PotosI, SLP (Mexico); Martinez-Mendoza, J R [Facultad de Ciencias, UASLP, Alvaro Obregon 64, CP 78000, San Luis PotosI, SLP (Mexico); Ruiz, Facundo [Facultad de Ciencias, UASLP, Alvaro Obregon 64, CP 78000, San Luis PotosI, SLP (Mexico)

    2008-02-13

    Silver nanoparticles with a narrow size distribution were synthesized over the surface of two different commercial TiO{sub 2} particles using a simple aqueous reduction method. The reducing agent used was NaBH{sub 4}; different molar ratios TiO{sub 2}:Ag were also used. The nanocomposites thus prepared were characterized using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), dynamic light scattering (DLS) and UV-visible (UV-vis) absorption spectroscopy; the antibacterial activity was assessed using the standard microdilution method, determining the minimum inhibitory concentration (MIC) according to the National Committee for Clinical Laboratory Standards. From the microscopy studies (TEM and STEM) we observed that the silver nanoparticles are homogeneously distributed over the surface of TiO{sub 2} particles and that the TiO{sub 2}:Ag molar ratio plays an important role. We used three different TiO{sub 2}Ag molar ratios and the size of the silver nanoparticles is 10, 20 and 80 nm, respectively. It was found that the antibacterial activity of the nanocomposites increases considerably comparing with separated silver nanoparticles and TiO{sub 2} particles.

  14. Characterization of silver nanoparticles synthesized on titanium dioxide fine particles

    International Nuclear Information System (INIS)

    Silver nanoparticles with a narrow size distribution were synthesized over the surface of two different commercial TiO2 particles using a simple aqueous reduction method. The reducing agent used was NaBH4; different molar ratios TiO2:Ag were also used. The nanocomposites thus prepared were characterized using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), dynamic light scattering (DLS) and UV-visible (UV-vis) absorption spectroscopy; the antibacterial activity was assessed using the standard microdilution method, determining the minimum inhibitory concentration (MIC) according to the National Committee for Clinical Laboratory Standards. From the microscopy studies (TEM and STEM) we observed that the silver nanoparticles are homogeneously distributed over the surface of TiO2 particles and that the TiO2:Ag molar ratio plays an important role. We used three different TiO2Ag molar ratios and the size of the silver nanoparticles is 10, 20 and 80 nm, respectively. It was found that the antibacterial activity of the nanocomposites increases considerably comparing with separated silver nanoparticles and TiO2 particles

  15. A facile route to synthesize silver nanoparticles in polyelectrolyte capsules.

    Science.gov (United States)

    Anandhakumar, S; Raichur, Ashok M

    2011-06-01

    We are reporting a novel green approach to incorporate silver nanoparticles (NPs) selectively in the polyelectrolyte capsule shell for remote opening of polyelectrolyte capsules. This approach involves in situ reduction of silver nitrate to silver NPs using PEG as a reducing agent (polyol reduction method). These nanostructured capsules were prepared via layer by layer (LbL) assembly of poly(allylamine hydrochloride) (PAH) and dextran sulfate (DS) on silica template followed by the synthesis of silver NPs and subsequently the dissolution of the silica core. The size of silver nanoparticles synthesized was 60±20 nm which increased to 100±20 nm when the concentration of AgNO(3) increased from 25 mM to 50 mM. The incorporated silver NPs induced rupture and deformation of the capsules under laser irradiation. This method has advantages over other conventional methods involving chemical agents that are associated with cytotoxicity in biological applications such as drug delivery and catalysis. PMID:21333503

  16. Synthesizing Econometric Evidence: The Case of Demand Elasticity Estimates.

    Science.gov (United States)

    DeCicca, Philip; Kenkel, Don

    2015-06-01

    Econometric estimates of the responsiveness of health-related consumer demand to higher prices are often key ingredients for risk policy analysis. We review the potential advantages and challenges of synthesizing econometric evidence on the price-responsiveness of consumer demand. We draw on examples of research on consumer demand for health-related goods, especially cigarettes. We argue that the overarching goal of research synthesis in this context is to provide policy-relevant evidence for broad-brush conclusions. We propose three main criteria to select among research synthesis methods. We discuss how in principle and in current practice synthesis of research on the price-elasticity of smoking meets our proposed criteria. Our analysis of current practice also contributes to academic research on the specific policy question of the effectiveness of higher cigarette prices to reduce smoking. Although we point out challenges and limitations, we believe more work on research synthesis in this area will be productive and important. PMID:25809022

  17. [Raman spectrum of nano-graphite synthesized by explosive detonation].

    Science.gov (United States)

    Wen, Chao; Li, Xun; Sun, De-Yu; Guan, Jin-Qing; Liu, Xiao-Xin; Lin, Ying-Rui; Tang, Shi-Ying; Zhou, Gang; Lin, Jun-De; Jin, Zhi-Hao

    2005-01-01

    The nano-graphite powder synthesized by the detonation of explosives with negative oxygen balance is a new powder material with potential applications. In this work, the preparation of nano-graphite powder in steel chamber by pure TNT (trinitrotoluene) explosives has been introduced. In the synthesis process, the protective gases in the steel chamber are N2, CO2 and Ar, and the pressure is 0.25-2 atm. Raman spectrum of the nano-graphite was measured. The characteristic Raman band assigned to sp2 of graphite has been observed at about 1 585 cm(-1) with half-peak width of 22 cm(-1). The peak shifted to a higher frequency by 5 cm(-1) compared with that of bulk graphite. The authors explain this blue shift phenomenon by size effect. The average size of nanographite from Raman measurement is 2.97-3.97 nm. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to measure the structure and particle size of the nano-graphite. The crystallite size of nano-graphite estimated from XRD andTEM are 2.58 nm (acid untreated) and 1.86 nm (acid treated) respectively, which is in accord with the results of the measurement approximately. PMID:15852818

  18. Radio-synthesized polyacrylamide hydrogels for proteins release

    Science.gov (United States)

    Ferraz, Caroline C.; Varca, Gustavo H. C.; Lopes, Patricia S.; Mathor, Monica B.; Lugão, Ademar B.

    2014-01-01

    The use of hydrogels for biomedical purposes has been extensively investigated. Pharmaceutical proteins correspond to highly active substances which may be applied for distinct purposes. This work concerns the development of radio-synthesized hydrogel for protein release, using papain and bovine serum albumin as model proteins. The polymer was solubilized (1% w/v) in water and lyophilized. The proteins were incorporated into the lyophilized polymer and the hydrogels were produced by simultaneous crosslinking and sterilization using γ-radiation under frozen conditions. The produced systems were characterized in terms of swelling degree, gel fraction, crosslinking density and evaluated according to protein release, bioactivity and cytotoxicity. The hydrogels developed presented different properties as a function of polymer concentration and the optimized results were found for the samples containing 4-5% (w/v) polyacrylamide. Protein release was controlled by the electrostatic affinity of acrylic moieties and proteins. This selection was based on the release of the proteins during the experiment period (up to 50 h), maintenance of enzyme activity and the nanostructure developed. The system was suitable for protein loading and release and according to the cytotoxic assay it was also adequate for biomedical purposes, however this method was not able to generate a matrix with controlled pore sizes.

  19. Mechanochemically Synthesized CIGS Nanocrystalline Powder for Solar Cell Application

    Directory of Open Access Journals (Sweden)

    Bharati Rehani

    2013-05-01

    Full Text Available Copper Indium Gallium Diselenide (CIGS is a compound semiconductor material from the group of I-III-VI. The material is a solid solution of copper, indium and selenium (CIS and copper, gallium and selenium with an empirical formula of CuIn(1 – xGaxSe2, where 0  x  1. CIGS has an exceptionally high absorption coefficient of more than 105 cm – 1 for 1.5 eV. Solar cells prepared from absorber layers of CIGS materials have shown an efficiency higher than 20 %. CuIn(1 – xGaxSe2 (x  0.3 nanocrystalline compound was mechanochemically synthesized by high-energy milling in a planetary ball mill. The phase identification and crystallite size of milled powders at different time intervals were carried out by X-ray diffraction (XRD. The XRD analysis indicates chalcopyrite structure and the crystallite size of about 10 nm of high-energy milled CIGS powder after two and half hours of milling. An attempt for preparing the thin film from CIGS nanocrystalline powder was carried out using the flash evaporation technique. Scanning electron microscopy (SEM reveals uniform distribution of CIGS particles in thin film.

  20. Mechanochemically synthesized fluorides: local structures and ion transport.

    Science.gov (United States)

    Preishuber-Pflügl, Florian; Wilkening, Martin

    2016-06-01

    The performance of new sensors or advanced electrochemical energy storage devices strongly depends on the active materials chosen to realize such systems. In particular, their morphology may greatly influence their overall macroscopic properties. Frequently, limitations in classical ways of chemical preparation routes hamper the development of materials with tailored properties. Fortunately, such hurdles can be overcome by mechanochemical synthesis. The versatility of mechanosynthesis allows the provision of compounds that are not available through common synthesis routes. The mechanical treatment of two or three starting materials in high-energy ball mills enables the synthesis not only of new compounds but also of nanocrystalline materials with unusual properties such as enhanced ion dynamics. Fast ion transport is of crucial importance in electrochemical energy storage. It is worth noting that mechanosynthesis also provides access to metastable phases that cannot be synthesized by conventional solid state synthesis. Ceramic synthesis routes often yield the thermally, i.e., thermodynamically, stable products rather than metastable compounds. In this perspective we report the mechanochemical synthesis of nanocrystalline fluorine ion conductors that serve as model substances to understand the relationship between local structures and ion dynamics. While ion transport properties were complementarily probed via conductivity spectroscopy and nuclear magnetic relaxation, local structures of the phases prepared were investigated by high-resolution (19)F NMR spectroscopy carried out by fast magic angle spinning. The combination of nuclear and non-nuclear techniques also helped us to shed light on the mechanisms controlling mechanochemical reactions in general. PMID:27172256

  1. Template-based syntheses for shape controlled nanostructures.

    Science.gov (United States)

    Pérez-Page, María; Yu, Erick; Li, Jun; Rahman, Masoud; Dryden, Daniel M; Vidu, Ruxandra; Stroeve, Pieter

    2016-08-01

    A variety of nanostructured materials are produced through template-based synthesis methods, including zero-dimensional, one-dimensional, and two-dimensional structures. These span different forms such as nanoparticles, nanowires, nanotubes, nanoflakes, and nanosheets. Many physical characteristics of these materials such as the shape and size can be finely controlled through template selection and as a result, their properties as well. Reviewed here are several examples of these nanomaterials, with emphasis specifically on the templates and synthesis routes used to produce the final nanostructures. In the first section, the templates have been discussed while in the second section, their corresponding synthesis methods have been briefly reviewed, and lastly in the third section, applications of the materials themselves are highlighted. Some examples of the templates frequently encountered are organic structure directing agents, surfactants, polymers, carbon frameworks, colloidal sol-gels, inorganic frameworks, and nanoporous membranes. Synthesis methods that adopt these templates include emulsion-based routes and template-filling approaches, such as self-assembly, electrodeposition, electroless deposition, vapor deposition, and other methods including layer-by-layer and lithography. Template-based synthesized nanomaterials are frequently encountered in select fields such as solar energy, thermoelectric materials, catalysis, biomedical applications, and magnetowetting of surfaces. PMID:27154387

  2. Differential transcriptome analysis between Paulownia fortunei and its synthesized autopolyploid.

    Science.gov (United States)

    Zhang, Xiaoshen; Deng, Minjie; Fan, Guoqiang

    2014-01-01

    Paulownia fortunei is an ecologically and economically important tree species that is widely used as timber and chemical pulp. Its autotetraploid, which carries a number of valuable traits, was successfully induced with colchicine. To identify differences in gene expression between P. fortunei and its synthesized autotetraploid, we performed transcriptome sequencing using an Illumina Genome Analyzer IIx (GAIIx). About 94.8 million reads were generated and assembled into 383,056 transcripts, including 18,984 transcripts with a complete open reading frame. A conducted Basic Local Alignment Search Tool (BLAST) search indicated that 16,004 complete transcripts had significant hits in the National Center for Biotechnology Information (NCBI) non-redundant database. The complete transcripts were given functional assignments using three public protein databases. One thousand one hundred fifty eight differentially expressed complete transcripts were screened through a digital abundance analysis, including transcripts involved in energy metabolism and epigenetic regulation. Finally, the expression levels of several transcripts were confirmed by quantitative real-time PCR. Our results suggested that polyploidization caused epigenetic-related changes, which subsequently resulted in gene expression variation between diploid and autotetraploid P. fortunei. This might be the main mechanism affected by the polyploidization. Our results represent an extensive survey of the P. fortunei transcriptome and will facilitate subsequent functional genomics research in P. fortunei. Moreover, the gene expression profiles of P. fortunei and its autopolyploid will provide a valuable resource for the study of polyploidization. PMID:24663058

  3. Carbon nanofibers synthesized by pyrolysis of chloroform and ethanol mixture

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Wang-Hua [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi, 62102, Taiwan (China); Li, Yuan-Yao, E-mail: chmyyl@ccu.edu.tw [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi, 62102, Taiwan (China); Graduate Institute of Opto-Mechatronics, National Chung Cheng University, Chia-Yi, 62102, Taiwan (China); Advanced Institute of Manufacturing with High-Tech Innovations, National Chung Cheng University, Chia-Yi, 62102, Taiwan (China)

    2015-08-01

    Platelet graphite nanofibers (PGNFs) and turbostratic carbon nanofibers (TSCNFs) were synthesized by the pyrolysis of 3 and 10 vol% chloroform in ethanol, respectively, in the presence of Ni catalyst at 700 °C. Auger electron spectrometry analysis reveals that the participation of chloroform in the synthesis led to Ni–Cl bonding on the surface of the catalysts, resulting in a relatively poor crystalline layer and a coarse surface. Furthermore, the Ni–Cl compound affected the melting point and mobility of Ni, changing the morphology and geometrical shape of Ni particles. A low amount of chlorine in the catalyst led to the formation of smaller catalyst particles with a flat surface, resulting in graphene nanosheets stacked perpendicular to the fiber axis, which became PGNFs. In contrast, a high amount of chlorine in the catalyst led to the aggregation of the catalyst and thus the formation of large catalyst particles with a rough surface, resulting in the random stacking of graphene nanosheets, which became TSCNFs. The participation of chlorine was found to be important in the synthesis of the PGNFs and TSCNFs. - Graphical abstract: Display Omitted - Highlights: • The morphology of CNFs changed while different amount of CHCl{sub 3} presented. • The interaction of Ni and Cl changed the geometry and morphology of catalysts. • The structure of CNFs formed attributed to the surface morphology of catalysts. • PGNFs and TSCNFs were perpendicular and random stacking of graphene.

  4. Physically synthesized Ni-Cu nanoparticles for magnetic hyperthermia

    Science.gov (United States)

    Bettge, Martin; Chatterjee, Jhunu; Haik, Yousef

    2004-01-01

    Background In this paper, a physical method to prepare copper-nickel alloy particles in the sub-micron range for possible self controlled magnetic hyperthermia treatment of cancer is described. It is reported that an increase in tumor temperature decreases the tumor resistance to chemo- and radiation therapies. Self controlled heating at the tumor site to avoid spot heating is managed by controlling the Curie temperature of the magnetic particles. The process described in this paper to produce the nanomagnetic particles allows for a large scale production of these particles. Methods The process used here is mainly composed of melting of the Cu-Ni mixture and ball milling of the resulted bulk alloy. Both mechanical abrasion and continuous grinding were used to break down the bulk amount into the desired particle size. Results It was found that the desired alloy is composed of 71% nickel and 29% copper by weight. It was observed that the coarse sand-grinded powder has a Curie temperature of 345 K and the fine ball-milled powder shows a temperature of 319 K – 320 K. Conclusion Self regulating magnetic hyperthermia can be achieved by synthesizing nanomagnetic particles with desired Curie temperature. In this study the desired range of Curie temperatures was obtained by combination of melting and ball milling of nickel-copper alloy. PMID:15132747

  5. Syntheses and crystal structures of two new organically templated borates

    International Nuclear Information System (INIS)

    Two new organically templated borates, [H3N(C6H10)NH3][B4O5(OH)4] (1) and [H3N(C6H10)NH3][B5O8(OH)] (2) have been synthesized in the presence of trans-1,4-diaminocyclohexane acting as a structure-directing agent under mild solvothermal conditions. The structures were determined by single crystal X-ray diffraction and further characterized by FTIR, elemental analysis and thermogravimetric analysis. Compound 1 crystallizes in the monoclinic system, space group C2/c (No. 15), a=9.1325(3)A, b=11.4869(3)A, c=12.2756(5)A, β=105.258(6)o, V=1242.37(7)A3, Z=4. The structure contains supramolecular hydrogen-bonded network formed by isolated [B4O5(OH)4]2- polyanions. 2 is monoclinic, space group P2(1)/n (No. 14), a=6.5176(2)A, b=16.8861(5)A, c=11.1522(7)A, β=91.897(6)o, V=1226.70(9)A3, Z=4. The structure consists of layers of 3,9-membered boron rings constructed from pentaborate anion groups [B5O8(OH)]2-. The adjacent borate layers are further linked with each other by hydrogen bond to form a 3D supramolecular network. It is the first example of layered borates templated by an organic amine

  6. Catalytically and biologically active silver nanoparticles synthesized using essential oil

    Science.gov (United States)

    Vilas, Vidya; Philip, Daizy; Mathew, Joseph

    2014-11-01

    There are numerous reports on phytosynthesis of silver nanoparticles and various phytochemicals are involved in the reduction and stabilization. Pure explicit phytosynthetic protocol for catalytically and biologically active silver nanoparticles is of importance as it is an environmentally benign green method. This paper reports the use of essential oil of Myristica fragrans enriched in terpenes and phenyl propenes in the reduction and stabilization. FTIR spectra of the essential oil and the synthesized biogenic silver nanoparticles are in accordance with the GC-MS spectral analysis reports. Nanosilver is initially characterized by an intense SPR band around 420 nm, followed by XRD and TEM analysis revealing the formation of 12-26 nm sized, highly pure, crystalline silver nanoparticles. Excellent catalytic and bioactive potential of the silver nanoparticles is due to the surface modification. The chemocatalytic potential of nanosilver is exhibited by the rapid reduction of the organic pollutant, para nitro phenol and by the degradation of the thiazine dye, methylene blue. Significant antibacterial activity of the silver colloid against Gram positive, Staphylococcus aureus (inhibition zone - 12 mm) and Gram negative, Escherichia coli (inhibition zone - 14 mm) is demonstrated by Agar-well diffusion method. Strong antioxidant activity of the biogenic silver nanoparticles is depicted through NO scavenging, hydrogen peroxide scavenging, reducing power, DPPH and total antioxidant activity assays.

  7. Production of chemoenzymatic catalyzed monoepoxide biolubricant: optimization and physicochemical characteristics.

    Science.gov (United States)

    Salimon, Jumat; Salih, Nadia; Abdullah, Bashar Mudhaffar

    2012-01-01

    Linoleic acid (LA) is converted to per-carboxylic acid catalyzed by an immobilized lipase from Candida antarctica (Novozym 435). This per-carboxylic acid is only intermediate and epoxidized itself in good yields and almost without consecutive reactions. Monoepoxide linoleic acid 9(12)-10(13)-monoepoxy 12(9)-octadecanoic acid (MEOA) was optimized using D-optimal design. At optimum conditions, higher yield% (82.14) and medium oxirane oxygen content (OOC) (4.91%) of MEOA were predicted at 15 μL of H(2)O(2), 120 mg of Novozym 435, and 7 h of reaction time. In order to develop better-quality biolubricants, pour point (PP), flash point (FP), viscosity index (VI), and oxidative stability (OT) were determined for LA and MEOA. The results showed that MEOA exhibited good low-temperature behavior with PP of -41(°)C. FP of MEOA increased to 128(°)C comparing with 115(°)C of LA. In a similar fashion, VI for LA was 224 generally several hundred centistokes (cSt) more viscous than MEOA 130.8. The ability of a substance to resist oxidative degradation is another important property for biolubricants. Therefore, LA and MEOA were screened to measure their OT which was observed at 189 and 168(°)C, respectively. PMID:22346338

  8. Chemo-enzymatic peptide synthesis : bioprocess engineering aspects

    NARCIS (Netherlands)

    Vossenberg, P.

    2012-01-01

      Peptides, in particular oligopeptides, play an important role in the fields of health care, nutrition and cosmetics. Chemical synthesis is currently the most mature technique for the synthesis of peptides that range in length from 5 to 80 amino acids. Chemical synthesis is, however, expected

  9. Chemoenzymatic Synthesis of Enantiopure 1,4-Dihydropyridine Derivates

    NARCIS (Netherlands)

    Sobolev, A.; Franssen, M.C.R.; Duburs, G.; Groot, de Æ.

    2004-01-01

    1,4-Dihydropyridines possess a broad range of biological activities, such as the ability to control the influx of calcium into cells, as well as neuroprotective, antineuro-degenerative, cognition and memory enhancing, anti-inflammatory, antiviral and many other properties. Chirality plays an importa

  10. Production of Chemoenzymatic Catalyzed Monoepoxide Biolubricant: Optimization and Physicochemical Characteristics

    Directory of Open Access Journals (Sweden)

    Jumat Salimon

    2012-01-01

    Full Text Available Linoleic acid (LA is converted to per-carboxylic acid catalyzed by an immobilized lipase from Candida antarctica (Novozym 435. This per-carboxylic acid is only intermediate and epoxidized itself in good yields and almost without consecutive reactions. Monoepoxide linoleic acid 9(12-10(13-monoepoxy 12(9-octadecanoic acid (MEOA was optimized using D-optimal design. At optimum conditions, higher yield% (82.14 and medium oxirane oxygen content (OOC (4.91% of MEOA were predicted at 15 μL of H2O2, 120 mg of Novozym 435, and 7 h of reaction time. In order to develop better-quality biolubricants, pour point (PP, flash point (FP, viscosity index (VI, and oxidative stability (OT were determined for LA and MEOA. The results showed that MEOA exhibited good low-temperature behavior with PP of −41°C. FP of MEOA increased to 128°C comparing with 115°C of LA. In a similar fashion, VI for LA was 224 generally several hundred centistokes (cSt more viscous than MEOA 130.8. The ability of a substance to resist oxidative degradation is another important property for biolubricants. Therefore, LA and MEOA were screened to measure their OT which was observed at 189 and 168°C, respectively.

  11. Chemoenzymatic preparative separation of silybins A and B

    Czech Academy of Sciences Publication Activity Database

    Křen, Vladimír; Gažák, Radek; Purchartová, Kateřina; Marhol, Petr; Biedermann, David; Sedmera, Petr

    2009-01-01

    Roč. 61, 3-4 (2009), s. 247-251. ISSN 1381-1177 R&D Projects: GA MŠk OC09045; GA AV ČR KJB400200701; GA ČR(CZ) GA303/08/0658 Institutional research plan: CEZ:AV0Z50200510 Keywords : Silymarin * Silibinin * Silybin A Subject RIV: CC - Organic Chemistry Impact factor: 2.400, year: 2009

  12. New effective chemically synthesized anti-smallpox compound NIOCH-14.

    Science.gov (United States)

    Mazurkov, Oleg Yu; Kabanov, Alexey S; Shishkina, Larisa N; Sergeev, Alexander A; Skarnovich, Maksim O; Bormotov, Nikolay I; Skarnovich, Maria A; Ovchinnikova, Alena S; Titova, Ksenya A; Galahova, Darya O; Bulychev, Leonid E; Sergeev, Artemiy A; Taranov, Oleg S; Selivanov, Boris A; Tikhonov, Alexey Ya; Zavjalov, Evgenii L; Agafonov, Alexander P; Sergeev, Alexander N

    2016-05-01

    Antiviral activity of the new chemically synthesized compound NIOCH-14 (a derivative of tricyclodicarboxylic acid) in comparison with ST-246 (the condensed derivative of pyrroledione) was observed in experiments in vitro and in vivo using orthopoxviruses including highly pathogenic ones. After oral administration of NIOCH-14 to outbred ICR mice infected intranasally with 100 % lethal dose of ectromelia virus, it was shown that 50 % effective doses of NIOCH-14 and ST-246 did not significantly differ. The 'therapeutic window' varied from 1 day before infection to 6 days post-infection (p.i.) to achieve 100-60 % survival rate. The administration of NIOCH-14 and ST-246 to mice resulted in a significant reduction of ectromelia virus titres in organs examined as compared with the control and also reduced pathological changes in the lungs 6 days p.i. Oral administration of NIOCH-14 and ST-246 to ICR mice and marmots challenged with monkeypox virus as compared with the control resulted in a significant reduction of virus production in the lungs and the proportion of infected mice 7 days p.i. as well as the absence of disease in marmots. Significantly lower proportions of infected mice and virus production levels in the lungs as compared with the control were demonstrated in experiments after oral administration of NIOCH-14 and ST-246 to ICR mice and immunodeficient SCID mice challenged with variola virus 3 and 4 days p.i., respectively. The results obtained suggest good prospects for further study of the chemical compound NIOCH-14 to create a new smallpox drug on its basis. PMID:26861777

  13. Zinc oxide flower-like synthesized under hydrothermal conditions

    International Nuclear Information System (INIS)

    One-dimensional zinc oxide with flower like configuration was synthesized onto a conductor glass substrate (fluorine-doped tin oxide — FTO) at 90 °C during 4 and 16 h. The zinc oxide formation occurs without any use of pre-seed layer or reactants to increase ionic strength of medium, neither addition of surfactant to act as capping agents for controlling morphology or special treatment on the commercial FTO substrate, making this an efficient and inexpensive procedure. X-ray diffraction analysis evidences a structure composed by single crystal in the wurtzite phase. The flower-like configuration observed by field emission scanning electronic microscopy images was promoted by the interaction between the reactant used to prepare the initial solution with pH adjusted at 10.5. This pH value is found, by titration study (triplicate) and in agreement with many reports in the literature, to promote the powder formation of zinc oxide with flower-like configuration. Tubular ZnO flower-like formation on the FTO was attributed to etching caused by ammonia in high concentration during the hydrothermal synthesis. In addition, our experimental results combined with theoretical ab initio calculation lead us to propose that the formation of tubular flower-like zinc oxide films proceeds in three steps, when prepared by hydrothermal process at different times (at T = 90 °C). - Highlights: • Mechanism of fast growth 1D zinc oxide nanostructure onto conductor glass substrate. • Tubular ZnO formation attributed to etching caused by ammonia in high concentration. • Three steps growth mechanism proposed for Zinc oxide tubular flower-like formation. • Theoretical calculation evidenced ZnO neck formation due hexagonal face dissolution

  14. Syntheses and properties of κ-phase organic superconductors

    International Nuclear Information System (INIS)

    The syntheses and physical properties of κ-(ET)2Cu[N(CN)2]X (X=Br and Cl) are summarized. The κ-(ET)2Cu[N(CN)2]Br salt is the highest Tc radical-cation based ambient pressure organic superconductor (Tc=11.6 K), and the κ-(ET)2Cu[N(CN)2]Cl salt becomes a superconductor at even higher Tc under 0.3 kbar hydrostatic pressure (Tc=12.8 K). The similarities and differences between κ-(ET)2Cu[N(CN)2]Br and κ-(ET)2Cu(NCS)2 (Tc=10.4 K) are presented. The X-ray structures at 127 K reveal that the the S hor-ellipsis S contacts shorten between ET dimers in the former compound while the S hor-ellipsis S contacts shorten within dimers in the latter. The difference in their ESR linewidth behavior is also explained in terms of the structural differences. A semiconducting compound, (ET)Cu[N(CN)2]2, isolated during κ-(ET)2Cu[N(CN)2]Cl synthesis is also reported. The ESR measurements of the κ-(ET)2Cu[N(CN)2]Cl salt indicate that the phase transition near 40 K is similar to the spin density wave transition in (TMTSF)2SbF6. A new class of organic superconductors, κ-(ET)2Cu2(CN)3 and κ-(ET)2Cu2(CN)3-δBrδ, is reported with Tc's of 2.8 K (1.5 kbar) and 2.6 K (1 kbar), respectively

  15. Electrochemically synthesized Si nano wire arrays and thermoelectric nano structures

    International Nuclear Information System (INIS)

    Thermoelectric nano structures hold great promise for capturing and directly converting into electricity some vast amount of low-grade waste heats now being lost to the environment (for example from nuclear power plant, fossil fuel burning, automotive and household appliances). In this study, large-area vertically-aligned silicon nano wire (SiNW) arrays were synthesized in an aqueous solution containing AgNO3 and HF on p-type Si (100) substrate by self-selective electroless etching process. The etching conditions were systematically varied in order to achieve different stages of nano wire formation. Diameters of the SiNWs obtained varied from approximately 50 to 200 nm and their lengths ranged from several to a few tens of μm. Te/ Bi2Te3-Si thermoelectric core-shell nano structures were subsequently obtained via galvanic displacement of SiNWs in acidic HF electrolytes containing HTeO2+ and Bi3+/ HTeO2+ ions. The reactions were basically a nano-electrochemical process due to the difference in redox potentials between the materials. the surface-modified SiNWs of core-shell structures had roughened surface morphologies and therefore, higher surface-t-bulk ratios compared to unmodified SiNWs. They have potential applications in sensors, photovoltaic and thermoelectric nano devices. Growth study on the SiNWs and core-shell nano structures produced is presented using various microscopy, diffraction and probe-based techniques for microstructural, morphological and chemical characterizations. (Author)

  16. Photoluminescence of Sequential Infiltration Synthesized ZnO nanostructures

    Science.gov (United States)

    Ocola, Leonidas; Gosztola, David; Yanguas-Gil, Angel; Connolly, Aine

    We have investigated a variation of atomic layer deposition (ALD), called sequential infiltration synthesis (SiS), as an alternate method to incorporate ZnO and other oxides inside polymethylmethacrylate (PMMA) and other polymers. Energy dispersive spectroscopy (EDS) results show that we synthesize ZnO up to 300 nm inside a PMMA film. Photoluminescence data on a PMMA film shows that we achieve a factor of 400X increase in photoluminescence (PL) intensity when comparing a blank Si sample and a 270 nm thick PMMA film, where both were treated with the same 12 alternating cycles of H2O and diethyl zinc (DEZ). PMMA is a well-known ebeam resist. We can expose and develop patterns useful for photonics or sensing applications first, and then convert them afterwards into a hybrid polymer-oxide material. We show that patterning does indeed affect the photoluminescence signature of native ZnO. We demonstrate we can track the growth of the ZnO inside the PMMA polymer using both photoluminescence and Raman spectroscopy and determine the point in the process where ZnO is first photoluminescent and also at which point ZnO first exhibits long range order in the polymer. This work was supported by the Department of Energy under Contract No. DE-AC02-06CH11357. Use of the Center for Nanoscale Materials was supported by the U. S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

  17. Amoxicillin Oxidative Degradation Synthesized by Nano Zero Valent Iron

    Directory of Open Access Journals (Sweden)

    AR Yazdanbakhsh

    2016-03-01

    Full Text Available Introduction: Amoxicillin is one of the most important groups of pharmaceuticals that benefits humans and animals. However, antibiotics excertion in wastewaters and environment have emerged as a serious risk to the biotic environment, and their toxic effects can harm the organisms. Iron-based metallic nanoparticles have received special attention in regard with remediation of groundwater contaminants. In the typical nZVI-based bimetallic particle system, Fe acts as the reducing agent. Thus, the present study aimed to evaluate the synthesis and characteristics of nZVI in regard with degrading AMX. Methods: In this study, nZVI nanoparticles were synthesized using the liquid-phase reduction method by EDTA as a stabilizer material. Structure and properties of nanoparticles were characterized by BET, SEM, XRD and EDX analysis. A multi-variate analysis was applied using a response surface methodology (RSM in order to develop a quadratic model as a functional relationship between AMX removal efficiency and independent variables ( initial pH values, dosage of nZVI, contact time and amoxicillin concentration. The four independent variables of solution pH (2–10, AMX concentration (5-45mg/l, contact time (5-85 min and nanoparticles dose (0.25 – 1.25 g were transformed to the coded values. Results: The study results demonstrated that more than 69 % of AMX was removed by nZVI. The optimal AMX removal conditions using nZVI were found as 1.25 g of nZVI, pH 4, contact time of 80 min and concentration of 30 mg/l. Conclusions: The ability of nZVI in degradation of AMX revealed that these materials can serve as a potential nano material with respect to the environmental remediation.

  18. Syntheses, Crystal Structures and Bioactivities of Two Novel Isatin Derivatives

    Institute of Scientific and Technical Information of China (English)

    SHANG Jian-li; LI Hui-dong; SHANG Jun; SONG Hai-bin; LI Zheng-ming; WANG Jian-guo

    2011-01-01

    Two novel compoundsl-(4-fluorobenzyl)-4-chloro-(Z)-3-benzoylhydrazono-2-indolinone(1) and 1-(4-methoxybenzyl)-(Z)-3-benzoylhydrazono-2-indolinone(2) were synthesized and their crystal structures were determined by single-crystal X-ray diffraction.Compound 1(C22H15ClFN3O2) crystallized in the triclinic system,space group P1- with a=0.94198(19) nm,b=1.4339(3) nm,c=1.5018(3) nm,a=101.58(3)°,β=102.96(3)°,γ=102.73°,V=1.8602(6) nm3,Mr=407.82,Dc=1.456 g/cm3,μ=0.240 mm-1,F(000)=840,Z=4,R1=0.0442 and wR2=0.1064.Compound 2(C23H19N3O3) crystallized in the triclinic system,space group P1- with a=1.0022(2) nm,b=1.0192(2) nm,c=1.0461(2) nm,a=99.86(3)°,β=117.30(3)°,γ=94.13(3)°,V=0.9215(3) nm3,Mr=385.41,Dc=1.389 g/cm3,μ=0.094mm-1,F(000)=404,Z=2,R1=0.0403 and wR2=0.1142.The preliminary herbicidal activities of the two compounds were also evaluated.

  19. Adsorption of citrate ions on hydroxyapatite synthesized by various methods

    International Nuclear Information System (INIS)

    The specific adsorption of citric acid ions at hydroxyapatite interface was investigated by the means of radioisotope method (14C) as a function of citric acid ions concentration, NaCl concentration and pH. Application of the hydroxyapatite has become wide in the biomaterial field as the Ca10(OH)2(PO4)6 possess biocompatibility with human hard tissue. Hydroxyapatite was synthesized using three different methods. The physical properties of the resulting powder were characterized by DTA/TG, XRD, AFM and SEM microscopy. Physicochemical qualities characterizing the electrical double layer of the hydroxyapatite/NaCl solution interface were determined. The zeta potential and the adsorption of citric acid molecule were studied as a function of pH. The point of zero charge and the isoelectric point of samples were determined. Electrical double layer parameters of hydroxyapatite/NaCl interface are influenced by a synthesis method. The points pHpzc and pHIEP for sample 1 are pHpzc 7.5 and pHIEP 3; for sample 2 pHpzc 7.05 and pHIEP 3, for sample 3 pHpzc 6.7 and pHIEP 3. Temperature has weak influence both on pure substance and with citric acid adsorbed, as derivatographic analysis has shown, and characterization of hydroxyapatite structure may be carried out by this thermal analysis. Two phenomena are responsible for citric acid adsorption: phosphate group's replacement at hydroxyapatite surface by citric ions parallel to intraspherical complexes formation. (author)

  20. The Semi-automatic Synthesis of 18F-fluoroethyl-choline by Domestic FDG Synthesizer

    Directory of Open Access Journals (Sweden)

    ZHOU Ming

    2016-02-01

    Full Text Available As an important complementary imaging agent for 18F-FDG, 18F-fluoroethyl-choline (18F-FECH has been demonstrated to be promising in brain and prostate cancer imaging. By using domestic PET-FDG-TI-I CPCU synthesizer, 18F-FECH was synthesized by different reagents and consumable supplies. The C18 column was added before the product collection bottle to remove K2.2.2. The 18F-FECH was synthesized by PET-FDG-IT-I synthesizer efficiently about 30 minutes by radiochemical yield of 42.0% (no decay corrected, n=5, and the radiochemical purity was still more than 99.0% after 6 hours. The results showed the domestic PET-FDG-IT-I synthesizer could semi-automatically synthesize injectable 18F-FECH in high efficiency and radiochemical purity

  1. An all-digital image synthesizer for countering high-resolution imaging radars

    OpenAIRE

    Ekestorm, Stig R.T.; Karow, Christopher

    2000-01-01

    The subject of this thesis is a digital image synthesizer (DIS), which is especially useful as a counter-targeting signal repeater, i.e., for synthesizing the characteristic echo signature of a pre-selected target. The DIS has a digital radio frequency memory (DRFM) and associated circuitry, including digital tapped delay lines and a modulator in each delay line to impose both amplitude and frequency modulation in each line. A unique property of the digital image synthesizer is its ability to...

  2. Photocatalytic activity of BiFeO3 nanoparticles synthesized through hydrothermal method

    International Nuclear Information System (INIS)

    Multiferroic BiFeO3 (BFO) nanoparticles (Nps) were synthesized using hydrothermal method. From the X-Ray diffraction analysis (XRD), the synthesized Nps were found to having rhombohedral structure with R3c space group confirmed by Rietveld analysis. Fourier transform infrared spectroscopy (FTIR) analysis was carried out to identify the chemical bonds present in the BFO Nps. Photocatalytic properties of synthesized Nps were studied for the degradation of Methylene Blue (MB) dye under visible light of 150W

  3. An all-digital image synthesizer for countering high-resolution imaging radars

    OpenAIRE

    Pace, Phillip E.; Ekestrom, S.; Karow, C.; Fouts, D.

    2000-01-01

    A digital image ssynthesizer (DIS), especially useful as a counter-targeting signal repeater, (i.e., for synthesizing the characteristic echo signature of a pre-selected target) is reported. The DIS has a digital radio frequency memory (DRFM) and associated circuitry, including digital tapped delay lines and a modulator in each delay line to impose both amplitude and frequency modulation in each line. A unique property of the digital image synthesizer is its ability to synthesize false targ...

  4. Complex Polymeric Architectures Synthesized and Functionalized using Robust Chemistries

    Science.gov (United States)

    Killops, Kathryn L.

    Niche applications for polymeric materials put stringent requirements on their properties and architecture. Although polymer synthesis techniques have improved significantly to produce well-defined materials with narrow molecular weight distributions from a variety of monomeric precursors, the final materials often require fine-tuning of the structure or functionality to achieve the properties necessary for a given high performance application. The ability to modify and synthesize soft materials in precise and predictable manner requires the use of robust, efficient, and orthogonal chemistries. The highly branched structure of dendrimers provides an ideal platform to rigorously evaluate the ability of a reaction to proceed with quantitative conversion and high specificity. In order to achieve a macromolecular structure having a monodisperse molecular weight of over 10,000 Da, highly efficient reactions must be used. The synthesis of dendrimers up to the fourth generation was accomplished using successive iterations of thiol--ene 'click' chemistry and esterification reactions. The high molecular weight dendrimers were subsequently derivitized at the periphery using a variety of functional groups to demonstrate the orthogonality of the thiol--ene reaction. An extension of this work provided direct comparison of the thermally- and photochemically-initiated thiol--ene reactions, as applied to the functionalization of polymers both along the backbone and at the chain ends. With block copolymers, access to nanoscale features is afforded by the propensity of two chemically-distinct, covalently-linked polymer chains phase separate into discrete domains. These nanoscopic features have important implications for high performance applications like microelectronics and water purification. Precise modification of these structures expands the number of applications that could benefit from their implementation. In the search for a poly(ethylene oxide)-based nanoparticle with

  5. Thermal properties of radiolytically synthesized PVA/Ag nanocomposites

    Directory of Open Access Journals (Sweden)

    Krklješ Aleksandra N.

    2007-01-01

    Full Text Available The radiolytic method was used to synthesize two types of nanocomposites with silver, PVA/Ag by film casting and PVA hydrogel/Ag nanocomposites. This method is particularly suitable for generating metal nanoparticles in solution. The radiolytic species (solvated electrons and secondary radicals exhibit strong reducing properties such that metal ions are reduced at each encounter. Metal atoms then tend to grow into larger clusters. It was found that solid or swollen polymers are able to stabilize small crystallites against spontaneous growth via aggregation. Using differential scanning calorimetry (DSC, the melting behavior and kinetics of the PVA/Ag nanocomposites were investigated and compared to those of pure PVA. The melting as well as crystallization behavior of polymers is crucial because it governs the thermal properties, impact resistance and stress strain properties. Understanding the melting behavior is significant not only to tailor the properties of nanocomposites but to investigate the interactions between the constituents. The DSC curves of pure PVA and prepared nanocomposites show only one melting peak between 175 and 230°C, indicating that the melting behavior of these two systems are analogous. In both cases, with increasing heating rate, the melting peak shifts to a higher temperature, but with increasing Ag content the peak melting temperature is lower. When specimens are heated at high heating rate, the motion of PVA molecular chains cannot follow the heating temperature on time due to the influence of heat hysteresis, which leads to a higher peak melting temperature. When Ag nanoparticles are added they increase the heat transfer among the PVA molecular chains decreasing the melting temperature. The Ag content is a major factor affecting the degree of crystallinity. It was observed that at low nanofiller content, up to the 0.5 wt%, the degree of crystallinity of the nanocomposites increased, while at a higher content the

  6. Computer Assisted Design, Prediction, and Execution of Economical Organic Syntheses

    Science.gov (United States)

    Gothard, Nosheen Akber

    The synthesis of useful organic molecules via simple and cost-effective routes is a core challenge in organic chemistry. In industry or academia, organic chemists use their chemical intuition, technical expertise and published procedures to determine an optimal pathway. This approach, not only takes time and effort, but also is cost prohibitive. Many potential optimal routes scratched on paper fail to get experimentally tested. In addition, with new methods being discovered daily are often overlooked by established techniques. This thesis reports a computational technique that assist the discovery of economical synthetic routes to useful organic targets. Organic chemistry exists as a network where chemicals are connected by reactions, analogous to citied connected by roads in a geographic map. This network topology of organic reactions in the network of organic chemistry (NOC) allows the application of graph-theory to devise algorithms for synthetic optimization of organic targets. A computational approach comprised of customizable algorithms, pre-screening filters, and existing chemoinformatic techniques is capable of answering complex questions and perform mechanistic tasks desired by chemists such as optimization of organic syntheses. One-pot reactions are central to modern synthesis since they save resources and time by avoiding isolation, purification, characterization, and production of chemical waste after each synthetic step. Sometimes, such reactions are identified by chance or, more often, by careful inspection of individual steps that are to be wired together. Algorithms are used to discover one-pot reactions and validated experimentally. Which demonstrate that the computationally predicted sequences can indeed by carried out experimentally in good overall yields. The experimental examples are chosen to from small networks of reactions around useful chemicals such as quinoline scaffolds, quinoline-based inhibitors of phosphoinositide 3-kinase delta (PI3

  7. Adsorption of multimeric T cell antigens on carbon nanotubes

    DEFF Research Database (Denmark)

    Fadel, Tarek R; Li, Nan; Shah, Smith;

    2013-01-01

    Antigen-specific activation of cytotoxic T cells can be enhanced up to three-fold more than soluble controls when using functionalized bundled carbon nanotube substrates ((b) CNTs). To overcome the denaturing effects of direct adsorption on (b) CNTs, a simple but robust method is demonstrated to...... stabilize the T cell stimulus on carbon nanotube substrates through non-covalent attachment of the linker neutravidin....

  8. Exploring architectures displaying multimeric presentations of a trihydroxypiperidine iminosugar

    Directory of Open Access Journals (Sweden)

    Camilla Matassini

    2015-12-01

    Full Text Available The synthesis of new multivalent architectures based on a trihydroxypiperidine α-fucosidase inhibitor is reported herein. Tetravalent and nonavalent dendrimers were obtained by means of the click chemistry approach involving the copper azide-alkyne-catalyzed cycloaddition (CuAAC between suitable scaffolds bearing terminal alkyne moieties and an azido-functionalized piperidine as the bioactive moiety. A preliminary biological investigation is also reported towards commercially available and human glycosidases.

  9. The Ability of Multimerized Cyclophilin A to Restrict Retrovirus Infection

    OpenAIRE

    Javanbakht, Hassan; Diaz-Griffero, Felipe; Yuan, Wen; Yeung, Darwin F.; Li, Xing; Song, Byeongwoon; Sodroski, Joseph

    2007-01-01

    In owl monkeys, the typical retroviral restriction factor of primates, TRIM5α, is replaced by TRIMCyp. TRIMCyp consists of the TRIM5 RING, B-box 2 and coiled-coil domains, as well as the intervening linker regions, fused with cyclophilin A. TRIMCyp restricts infection of retroviruses, such as human immunodeficiency virus (HIV-1) and feline immunodeficiency virus (FIV), with capsids that can bind cyclophilin A. The TRIM5 coiled coil promotes the trimerization of TRIMCyp. Here we show that cycl...

  10. Enhanced membrane pore formation by multimeric/oligomeric antimicrobial peptides.

    Science.gov (United States)

    Arnusch, Christopher J; Branderhorst, Hilbert; de Kruijff, Ben; Liskamp, Rob M J; Breukink, Eefjan; Pieters, Roland J

    2007-11-20

    The pore-forming antibacterial peptide magainin 2 was made divalent, tetravalent, and octavalent via a copper(I)-mediated 1-3 dipolar cycloaddition reaction ("click" chemistry). This series of pore-forming compounds was tested in vitro for their ability to form pores in large unilamillar vesicles (LUVs). A large increase in the pore-forming capability was especially observed with the tetravalent and octavalent magainin compounds in the LUVs consisting of DOPC, and the octavalent magainin compound showed a marked increase with the DOPC/DOPG LUVs. Activity was observed in the low nanomolar range for these compounds. PMID:17944489

  11. Enhanced membrane pore information by multimeric/oligomeric antimicrobial peptides

    OpenAIRE

    Arnusch, C.J.; Branderhorst, H.M.; de Kruijff, B.; Liskamp, R. M. J.; Breukink, E.J.; Pieters, R. J.

    2007-01-01

    The pore-forming antibacterial peptide magainin 2 was made divalent, tetravalent, and octavalent via a copper(I)-mediated 1-3 dipolar cycloaddition reaction (“click” chemistry). This series of poreforming compounds was tested in vitro for their ability to form pores in large unilamillar vesicles (LUVs). A large increase in the pore-forming capability was especially observed with the tetravalent and octavalent magainin compounds in the LUVs consisting of DOPC, and the octavalent magainin compo...

  12. Exploring architectures displaying multimeric presentations of a trihydroxypiperidine iminosugar

    Science.gov (United States)

    Matassini, Camilla; Mirabella, Stefania; Goti, Andrea; Robina, Inmaculada; Moreno-Vargas, Antonio J

    2015-01-01

    Summary The synthesis of new multivalent architectures based on a trihydroxypiperidine α-fucosidase inhibitor is reported herein. Tetravalent and nonavalent dendrimers were obtained by means of the click chemistry approach involving the copper azide-alkyne-catalyzed cycloaddition (CuAAC) between suitable scaffolds bearing terminal alkyne moieties and an azido-functionalized piperidine as the bioactive moiety. A preliminary biological investigation is also reported towards commercially available and human glycosidases. PMID:26734108

  13. Linker-mediated assembly of gold nanoparticles into multimeric motifs

    Science.gov (United States)

    Sikora, Mateusz; Szymczak, Piotr; Thompson, Damien; Cieplak, Marek

    2011-11-01

    We present a theoretical description of linker-mediated self-assembly of gold nanoparticles (Au-NP). Using mesoscale simulations with a coarse-grained model for the Au NPs and dirhenium-based linker molecules, we investigate the conditions under which large clusters can grow and construct a phase diagram that identifies favorable growth conditions in terms of floating and bound linker concentrations. The findings can be considered as generic, as we expect other NP-linker systems to behave in a qualitatively similar way. In particular, we also discuss the case of antibody-functionalised Au NPs connected by the C-reactive proteins (CRPs). We extract some general rules for NP linking that may aid the production of size- and shape-specific NP clusters for technology applications.

  14. Linker-mediated assembly of gold nanoparticles into multimeric motifs

    Energy Technology Data Exchange (ETDEWEB)

    Sikora, Mateusz; Cieplak, Marek [Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668 Warsaw (Poland); Szymczak, Piotr [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, ulica Hoza 69, 00-681 Warsaw (Poland); Thompson, Damien, E-mail: mc@ifpan.edu.pl [Tyndall National Institute, Lee Maltings, University College Cork, Cork (Ireland)

    2011-11-04

    We present a theoretical description of linker-mediated self-assembly of gold nanoparticles (Au-NP). Using mesoscale simulations with a coarse-grained model for the Au NPs and dirhenium-based linker molecules, we investigate the conditions under which large clusters can grow and construct a phase diagram that identifies favorable growth conditions in terms of floating and bound linker concentrations. The findings can be considered as generic, as we expect other NP-linker systems to behave in a qualitatively similar way. In particular, we also discuss the case of antibody-functionalised Au NPs connected by the C-reactive proteins (CRPs). We extract some general rules for NP linking that may aid the production of size- and shape-specific NP clusters for technology applications.

  15. Multimeric hemoglobin of the Australian brine shrimp Parartemia.

    Science.gov (United States)

    Coleman, M; Matthews, C M; Trotman, C N

    2001-04-01

    The hemoglobin molecule of the commercially important brine shrimp Artemia sp. has been used extensively as a model for the study of molecular evolution. It consists of nine globin domains joined by short linker sequences, and these domains are believed to have originated through a series of duplications from an original globin gene. In addition, in Artemia, two different polymers of hemoglobin, called C and T, are found which differ by 11.7% at the amino acid level and are believed to have diverged about 60 MYA. This provides a set of data of 18 globin domain sequences that have evolved in the same organism. The pattern of amino acid substitution between these two polymers is unusual, with pairs of equivalent domains displaying differences of up to 2.7-fold in total amino acid substitution. Such differences would reflect a similar range of molecular-clock rates in what appear to be duplicate, structurally equivalent domains. In order to provide a reference outgroup, we sequenced the cDNA for a nine-domain hemoglobin (P) from another genus of brine shrimp, Parartemia zietziana, which differs morphologically and ecologically from Artemia and is endemic to Australia. Parartemia produces only one hundredth the amount of hemoglobin that Artemia produces and does not upregulate production in response to low oxygen partial pressure. Comparison of the globin domains at the amino acid and DNA levels suggests that the Artemia globin T gene has accumulated substitutions differently from the Parartemia P and Artemia C globin genes. We discuss the questions of accelerated evolution after duplication and possible functions for the Parartemia globin. PMID:11264409

  16. Observing System Simulations for ASCENDS: Synthesizing Science Measurement Requirements (Invited)

    Science.gov (United States)

    Kawa, S. R.; Baker, D. F.; Schuh, A. E.; Crowell, S.; Rayner, P. J.; Hammerling, D.; Michalak, A. M.; Wang, J. S.; Eluszkiewicz, J.; Ott, L.; Zaccheo, T.; Abshire, J. B.; Browell, E. V.; Moore, B.; Crisp, D.

    2013-12-01

    The measurement of atmospheric CO2 from space using active (lidar) sensing techniques has several potentially significant advantages in comparison to current and planned passive CO2 instruments. Application of this new technology aims to advance CO2 measurement capability and carbon cycle science into the next decade. The NASA Active Sensing of Carbon Emissions, Nights, Days, and Seasons (ASCENDS) mission has been recommended by the US National Academy of Sciences Decadal Survey for the next generation of space-based CO2 observing systems. ASCENDS is currently planned for launch in 2022. Several possible lidar instrument approaches have been demonstrated in airborne campaigns and the results indicate that such sensors are quite feasible. Studies are now underway to evaluate performance requirements for space mission implementation. Satellite CO2 observations must be highly precise and unbiased in order to accurately infer global carbon source/sink fluxes. Measurement demands are likely to further increase in the wake of GOSAT, OCO-2, and enhanced ground-based in situ and remote sensing CO2 data. The objective of our work is to quantitatively and consistently evaluate the measurement capabilities and requirements for ASCENDS in the context of advancing our knowledge of carbon flux distributions and their dependence on underlying physical processes. Considerations include requirements for precision, relative accuracy, spatial/temporal coverage and resolution, vertical information content, interferences, and possibly the tradeoffs among these parameters, while at the same time framing a mission that can be implemented within a constrained budget. Here, we attempt to synthesize the results of observing system simulation studies, commissioned by the ASCENDS Science Requirements Definition Team, into a coherent set of mission performance guidelines. A variety of forward and inverse model frameworks are employed to reduce the potential dependence of the results on model

  17. A solvothermal method for synthesizing monolayer protected amorphous calcium carbonate clusters.

    Science.gov (United States)

    Sun, Shengtong; Gebauer, Denis; Cölfen, Helmut

    2016-05-19

    A solvothermal method was developed for synthesizing organic monolayer protected amorphous calcium carbonate clusters using 10,12-pentacosadiynoic acid as ligand, ethanol as solvent and NaHCO3 decomposition as CO2 source, which can be extended to synthesize other monolayer protected mineral clusters. PMID:27161807

  18. Newly synthesized hypoxia-mediated drugs as radiosensitizers and cytotoxic agents

    International Nuclear Information System (INIS)

    This paper describes experiments with mammalian cells in vitro to compare the radiosensitizing and cytotoxic properties of five newly synthesized hypoxia mediated drugs with the current drug in use, misonidazole. Attention has focused on the need to synthesize or identify compounds with equal or greater effectiveness but at the same time exhibiting less serious side effects

  19. Syntheses and absorption-structure relationships of some new photosensitizer cyanine dyes

    Indian Academy of Sciences (India)

    H A Shindy; A I M Koraiem

    2002-04-01

    New biheterocyclic compound was synthesized as starting material to prepare new photosensitizers mono-, tri-, substituted tri-, azadimethine and mixed cyanine dyes. Absorption-structure relationship of the synthesized cyanine dyes were determined by studying their electronic spectral behaviour in ethanol. The structure of the compounds were identified by elemental analysis, IR and 1H NMR spectral data.

  20. Electronic Transport in Chemical Vapor Deposited Graphene Synthesized on Cu: Quantum Hall Effect and Weak Localization

    OpenAIRE

    Cao, H. L.; Yu, Q. K.; Jauregui, L. A.; Tian, J; Wu, W.; Z. Liu; Jalilian, R.; Benjamin, D. K.; Jiang, Z.; J. Bao; Pei, S S; Chen, Y P

    2009-01-01

    We report on electronic properties of graphene synthesized by chemical vapor deposition (CVD) on copper then transferred to SiO2/Si. Wafer-scale (up to 4 in.) graphene films have been synthesized, consisting dominantly of monolayer graphene as indicated by spectroscopic Raman mapping. Low temperature transport measurements are performed on microdevices fabricated from such CVD graphene, displaying ambipolar field ...

  1. A Two-Stage Approach to Synthesizing Covariance Matrices in Meta-Analytic Structural Equation Modeling

    Science.gov (United States)

    Cheung, Mike W. L.; Chan, Wai

    2009-01-01

    Structural equation modeling (SEM) is widely used as a statistical framework to test complex models in behavioral and social sciences. When the number of publications increases, there is a need to systematically synthesize them. Methodology of synthesizing findings in the context of SEM is known as meta-analytic SEM (MASEM). Although correlation…

  2. Simple syntheses of 3-substituted indoles and their application for high yield 14C-labelling

    International Nuclear Information System (INIS)

    Methods are described which allow the synthesis of several plant indole alkaloids and their metabolites at different scales. Compounds synthesized include gramine (1) (3-dimethylaminomethylindole) which is directly derived from indole, while its biosynthetic precursors 3-aminomethylindole (3) and 3-methylaminomethylindole (2) as well as indole3-carboxylic acid (7) are synthesized via indole-3-aldehyde (6). Slight changes of the experimental conditions allow syntheses with high yields not only at the molar but also at the μmolar level. This is extremely useful when isotope labelled compounds of high specific radioactivity are required for studies of plant metabolism. (orig.)

  3. Bismuth onion thin film in situ grown on silicon wafer synthesized through a hydrothermal approach

    International Nuclear Information System (INIS)

    Bismuth onion structured nanospheres with the same structure as carbon onions have been synthesized and observed. The nanospheres were synthesized through a hydrothermal method using bismuth hydroxide and silicon wafer as reactants. By controlling the heating temperature, heating time, and the pressure, nanoscale bismuth spheres can be in situ synthesized on silicon wafer, and forms a bismuth onion film on the substrate. The electronic property of the films was investigated. A formation mechanism of the formation of bismuth onions and the onion film has been proposed on the basis of experimental observations.

  4. Optical authentication via photon-synthesized ghost imaging using optical nonlinear correlation

    Science.gov (United States)

    Chen, Wen; Chen, Xudong

    2015-10-01

    We present a method for optical authentication via photon-synthesized ghost imaging using optical nonlinear correlation. In ghost imaging, multiple series of photons recorded at the object beam arm can be arbitrarily controlled for the generation of synthesized objects. Ghost imaging with sparse reference intensity patterns provides a channel to effectively modulate the noise-like synthesized objects during the recovery, and the reconstructed (noise-like) objects, i.e., added or subtracted information, can be further authenticated by optical nonlinear correlation algorithm. It is expected that the proposed method can provide an effective and promising alternative for ghost-imaging-based optical processing.

  5. M10.6.6: Designed and manufactured Frequency Synthesizer Board (AMC)

    CERN Document Server

    Czuba, K

    2011-01-01

    The LLRF system require generation of highly stable clock and trigger signals for high precision data processing and synchronous system operation. This deliverable provides an updated AMC module designed to fulfill the LLRF system timing synchronization needs. The module contains three independent clock synthesizers that are able to generate LVDS clock signals in the range of 10 MHz to 100 MHz. The clock synthesizers can be synchronized either by an internal quartz oscillator or an external phase reference signal provided to the board from the FLASH Master Oscillator. Besides clock synthesizers the AMC card contains also an optical receiver suited to convert and decode FLASH timing signals.

  6. Superparamagnetic properties nano Ni-Zn ferrite synthesized via reverse micelle technique

    International Nuclear Information System (INIS)

    Nanocrystalline nickel-zinc ferrite (Ni0.58Zn0.42Fe2O4) with average grain size of 9 nm was synthesized by reverse micelle technique. The size of particles was confirmed by XRD, TEM. Synthesized, as dried and subsequently calcined powders were characterized in terms of their magnetic properties with the use of SQUID suseptometer. Ferrite nanoparticles revealed the superparamagnetism at room temperature and shows negligible hysteresis at low temperature (5 K). Saturation magnetization of the as synthesized powders is low as compared to its bulk counterpart. (author)

  7. Interfacially synthesized PAni–PMo12 hybrid material for supercapacitor applications

    Indian Academy of Sciences (India)

    Arumugam Manivel; Abdullah M Asiri; Khalid Ahmad Alamry; Teresa Lana-Villarreal; Sambandam Anandan

    2014-06-01

    The concept of interfacial polymerization is utilized for the synthesis of polyaniline–phosphomolybdate (PAni–PMo12) molecular hybrids and it is well characterized. The electrical conductivity of the synthesized hybrid materials increases with increase in PMo12 wt%. The synthesized hybrid materials are evaluated as the active electrode materials for supercapacitor application. Cyclic voltammetric studies of the hybrid-modified electrode shows broad parallelogram-shaped peak as an evidence for pseudo-capacitive behaviour. The galvanostatic charge–discharge studies enlighten that interfacially synthesized hybrid materials loaded with PMo12 show relatively enhanced specific capacitance values than PMo12 free samples.

  8. Effect of annealing on the structure of chemically synthesized SnO2 nanoparticles

    Science.gov (United States)

    Singh, Kulwinder; Kumar, Virender; Vij, Ankush; Kumari, Sudesh; Kumar, Akshay; Thakur, Anup

    2016-05-01

    Tin oxide (SnO2) nanoparticles have been synthesized by co-precipitation method. The synthesized nanoparticles were characterized by X-ray diffraction (XRD) and Raman spectroscopy. XRD analysis confirmed the single phase formation of SnO2 nanoparticles. The Raman shifts showed the typical feature of the tetragonal phase of the as-synthesized SnO2 nanoparticles. At low annealing temperature, a strong distortion of the crystalline structure and high degree of agglomeration was observed. It is concluded that the crystallinity of SnO2 nanoparticles improves with the increase in annealing temperature.

  9. Expanding the plateau of high-order harmonic spectrum by multi-color synthesized laser field

    International Nuclear Information System (INIS)

    We propose a scheme to extend the plateau of high-order harmonic spectrum by using multi- color synthesized laser field. Firstly, the two-color and three-color laser fields are synthesized by adding control laser pulse to the 800 nm fundamental pulse. Secondly, the high-order harmonic spectra are presented via numerically solving the one-dimensional time-dependent Schrodinger equation in multi-color synthesized laser field, and the results show that the width can be expended effectively. Finally, the high-order harmonic spectra are explained reasonably by means of classical returning kinetic-energy map and the time-frequency distribution. (authors)

  10. Methods for synthesizing alane without the formation of adducts and free of halides

    Science.gov (United States)

    Zidan, Ragaiy; Knight, Douglas A; Dinh, Long V

    2013-02-19

    A process is provided to synthesize an alane without the formation of alane adducts as a precursor. The resulting product is a crystallized .alpha.-alane and is a highly stable product and is free of halides.

  11. Efficient Syntheses of 2-Substituted Benzimidazoles and Benzoxazoles from β-Keto Esters

    Institute of Scientific and Technical Information of China (English)

    XIAO Li-wei; ZHANG Min; SUN Wen-hua

    2011-01-01

    An efficient synthetic method was developed to synthesize 2-substituted benzimidazoles and benzoxazoles withβ-keto esters as starting materials under mild reaction conditions, during which other functional groups are bearable from reactants to products.

  12. Mesoporous Silica Materials Synthesized via Sol-Gel Methods Modified with Ionic Liquid and Surfactant Molecules

    Institute of Scientific and Technical Information of China (English)

    Cun-ying Xu; Ru-lan Tang; Yi-xin Hu; Peng-xiang Zhang

    2008-01-01

    Mesoporous silica materials were synthesized via a sol-gel method employing a room temperature ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF4]) as a new solvent medium and further modified with surfactant (hexadecyl-trimethyl-ammonium bromide, CTAB) as a pore templating material. The synthesized samples were characterized by the transmission electron microscopy, X-ray diffraction, and N2 adsorption-desorption techniques. The results indicated that the mesoporous silica synthesized by using [bmim][BF4] and CTAB as mixed templates showed better mesostructural order and smaller pore size, compared with mesoporous silica materials synthesized by using single [bmim][BF4]as template under the same conditions. This indicates that the presence of surfactant can affect the microstructures of silica prepared by the present synthesis method.

  13. Syntheses of environmentally friendly amide derivatives for the selective separation of actinides based on oxidation states

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Seung; Choi, Jung Kyu; Lee, Yeon Ok; Yoon, Jun Hee [Dankook Univ., Seoul (Korea, Republic of)

    2007-08-15

    Syntheses of environmentally friendly amide derivatives for the selective separation of actinides were studied. As for the ligand, we have synthesized TODGA (N,N-Tetraoctyl diglycolamide), DHOA (N,N-Dihexyloctaneamide), and D2EHBA (N,N-Di(2-ethyl)hexylbutanamide) in high yield. The amide derivative was successfully prepared by chlorination followed by amination method in a good synthetic yield. The structures of all synthetic precursors and final products were confirmed by NMR, IR, and Mass spectrophotometer.

  14. Synthesized and inherited functions - a new computational model for syntax-directed semantics

    OpenAIRE

    Vogler, Heiko; Kühnemann, Armin

    2009-01-01

    In this paper we introduce a new formal model for the concept of syntax--directed semantics, called macro attributed tree transducer (for short: mat tree transducer). This model is based on (noncircular) attributed tree transducers and on macro tree transducers. In the first type of transducer, semantic values are computed by means of meaning names called synthesized attributes, and by means of context names called inherited attributes. Both, synthesized and inherited attributes represent bas...

  15. Synthesize, optimize, analyze, repeat (SOAR): Application of neural network tools to ECG patient monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Watrous, R.; Towell, G.; Glassman, M.S. [Siemens Corporate Research, Princeton, NJ (United States)

    1995-12-31

    Results are reported from the application of tools for synthesizing, optimizing and analyzing neural networks to an ECG Patient Monitoring task. A neural network was synthesized from a rule-based classifier and optimized over a set of normal and abnormal heartbeats. The classification error rate on a separate and larger test set was reduced by a factor of 2. When the network was analyzed and reduced in size by a factor of 40%, the same level of performance was maintained.

  16. Synthesis and properties of epoxydized cooligomers obtained from petroleum resins synthesized by heterogeneous catalytic oligomerization

    OpenAIRE

    Voronchak, Taras; Nykulyshyn, Irena; Pikh, Zorian; Rypka, Anna

    2012-01-01

    Synthesis of cooligomers with epoxy groups was studied. They were synthesized by epoxidation of unsaturated petroleum resins obtained by heterogeneous catalytic oligomerization of liquid pyrolysis products С9 fraction. The degree of unsaturated bonds conversion and the selectivity of epoxidation process were calculated. The properties of epoxydized cooligomers were determined and analyzed. The structurization of synthesized products in the composition of composites with epoxy resin ED-20 ...

  17. Recent Progress on Enyne Metathesis: Its Application to Syntheses of Natural Products and Related Compounds

    OpenAIRE

    Miwako Mori

    2010-01-01

    Olefin metathesis using ruthenium carbene complexes is a useful method in synthetic organic chemistry. Enyne metathesis is also catalyzed by these complexes and various carbo- and heterocycles could be synthesized from the corresponding enynes. Dienyne metathesis, cross enyne metathesis and ring-opening enyne metathesis have been further developed. Various complicated compounds, such as the natural products and the related biologically active substances, could be synthesized using these metat...

  18. Multi-Tone Millimeter-Wave Frequency Synthesizer for Atmospheric Propagation Studies

    Science.gov (United States)

    Simons, Rainee N.; Wintucky, Edwin G.

    2014-01-01

    The design and test results of a multi-tone millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator is presented. The intended applications of the synthesizer is in a space-borne transmitter for radio wave atmospheric studies at Q-band (37 to 43 GHz). These studies would enable the design of robust high data rate space-to-ground satellite communication links.

  19. Studing Tungsten-containing Electroerosion Powders and Alloys Synthesized from Them

    Directory of Open Access Journals (Sweden)

    E.V. Ageev

    2014-07-01

    Full Text Available The results of the X-ray spectral microanalysis of the powder obtained using electroerosion dispersion of tungsten-containing wastes in distilled water, and the alloy powder synthesized from this powder are presented in the article. It is shown that the basic elements both in the powder obtained using electroerosion dispersion of tungsten-containing wastes in distilled water and in the synthesized alloy are tungsten, molybdenum, iron, oxygen and carbon.

  20. Pineapple fruit bromelain recovery using recyclable functionalized ordered mesoporous silica synthesized from sugarcane leaf ash

    OpenAIRE

    A. Arumugam; V. Ponnusami

    2013-01-01

    Bromelain, a protease enzyme found in Ananas comosus (Pineapple), was recovered from the fruit juice by adsorption using recyclable functionalized Santa Barbara Acid-15 (SBA-15) synthesized from sugarcane leaf ash. In this work, highly ordered mesoporous silica was synthesized from sugarcane leaf ash by a template-assisted method. It was successfully used as an adsorbent for the recovery of bromelain from pineapple fruit pulp. Amine-functionalized mesoporous silica exhibited a recovery effici...

  1. A.Flavus Mediated Biotransformations for the Syntheses of Active A-oxyfunctionalized Compounds

    Institute of Scientific and Technical Information of China (English)

    P.Ayhan; S.Betul; Sopaci; A.S.Demir

    2007-01-01

    1 Results Biotransformations are enzyme- and whole cell-catalysed conversions of non-natural substrates to products.They are important tools in organic synthesis,especially for the syntheses of chiral molecules,where the reactions catalysed may be asymmetric syntheses or the resolution of racemates.The main advantages associated with the use of single enantiomer compounds are increased specificity and the avoidance of adverse side effects[1].Whole cell reactions are advantegous over enzyme-catalyzed rea...

  2. Meteorite-catalyzed syntheses of nucleosides and of other prebiotic compounds from formamide under proton irradiation

    OpenAIRE

    Saladino, Raffaele; Carota, Eleonora; Botta, Giorgia; Kapralov, Mikhail; Timoshenko, Gennady N.; Rozanov, Alexei Y.; Krasavin, Eugene; Di Mauro, Ernesto

    2015-01-01

    Modern research on the origin of life started with Urey–Miller’s 1953 report on the spontaneous formation of amino acids upon application of electric discharge on a model of the pristine Earth atmosphere. Formamide provides a chemically sound starting material for the syntheses of prebiotic compounds; its role in prebiotics is becoming recognized. Kiloparsecs-wide clouds of formamide were observed in the interstellar space. The energy sources for the syntheses explored so far were largely the...

  3. Characterization and Neutron Shielding Behavior of Dehydrated Magnesium Borate Minerals Synthesized via Solid-State Method

    OpenAIRE

    Azmi Seyhun Kipcak; Derya Yilmaz Baysoy; Emek Moroydor Derun; Sabriye Piskin

    2013-01-01

    Magnesium borates are one of the major groups of boron minerals that have good neutron shielding performance. In this study, dehydrated magnesium borates were synthesized by solid-state method using magnesium oxide (MgO) and boron oxide (B2O3), in order to test their ability of neutron shielding. After synthesizing the dehydrated magnesium borates, characterizations were done by X-ray Diffraction (XRD), fourier transform infrared (FT-IR), Raman spectroscopy, and scanning electron microscopy (...

  4. Improved Permeate Flux of PVDF Ultrafiltration Membrane Containing PVDF-g-PHEA Synthesized via ATRP

    OpenAIRE

    Kwang-Mo Kim; Sahng Hyuck Woo; Ju Sung Lee; Hyun Sic Park; Jinwon Park; Byoung Ryul Min

    2015-01-01

    Polyvinylidene fluoride (PVDF) ultrafiltration (UF) membrane combined with polyvinylidene fluoride-graft-2-hydroxyethyl acrylate (PVDF-g-PHEA) was fabricated via non-solvent induced phase separation (NIPS). In this study, PVDF-g-PHEA was synthesized via atom transfer radical polymerization (ATRP) method, and then synthesized graft copolymer was characterized using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and thermogravimetry analysis (TGA). Moreover, PV...

  5. Bridging the Gap between faculty Expectation and Student Experience: Teaching Students to Annotate and Synthesize Sources

    OpenAIRE

    Cuthbertson, William; Markowski, Brianna

    2016-01-01

    Faculty across college campuses lament that students don't know how to read, evaluate, synthesize, and appropriately cite academic literature. Students express similar concerns. This presentation offers activities designed to demystify and empower students in learning two key steps of academic research: compiling bibliographic information and writing evaluative annotations, and reading and synthesizing academic journal articles. Attendees of the presentation will leave with information on the...

  6. Diversity Oriented Syntheses of Conventional Heterocycles by Smart Multi Component Reactions (MCRs of the Last Decade

    Directory of Open Access Journals (Sweden)

    Heiner Eckert

    2012-01-01

    Full Text Available A collection of smart multicomponent reactions (MCRs with continuative post condensation cyclizations (PCCs is presented to construct conventional three- to seven-membered heterocyclic compounds in diversity oriented syntheses (DOS. These will provide a high degree of applying economical and ecological advantages as well as of practicability. Water, ionic liquids, and solvent-less syntheses as well as use of various forms of energy as microwave and ultrasonic irradiation are examined and discussed.

  7. Four proteins synthesized in response to deoxyribonucleic acid damage in Micrococcus radiodurans.

    OpenAIRE

    Hansen, M T

    1980-01-01

    Four proteins, alpha beta, gamma, and delta, preferentially synthesized in ultraviolet light-treated cells of Micrococcus radiodurans, were characterized in terms of their molecular weights and isoelectric points. Within the sublethal-dose range, the differential rate of synthesis for these proteins increased linearly with the inducing UV dose. The degree of induction reached 100-fold, and the most abundant protein beta, amounted to approximately 2% of the total newly synthesized protein afte...

  8. Photocatalytic degradation of organic compounds over combustion-synthesized nano-TiO2.

    Science.gov (United States)

    Nagaveni, K; Sivalingam, G; Hegde, M S; Madras, Giridhar

    2004-03-01

    The photocatalytic degradation of various organics such as phenol, p-nitrophenol, and salicylic acid was carried out with combustion-synthesized nano-TiO2 under UV and solar exposure. Under identical conditions of UV exposure, the initial degradation rate of phenol with combustion-synthesized TiO2 is 2 times higher than the initial degradation rate of phenol with commercial Degussa P-25 TiO2. The intermediates such as catechol (CC) and hydroquinone (HQ) were not detected during the degradation of phenol with combustion-synthesized TiO2, while both the intermediates were detected when phenol was degraded over Degussa P-25. This indicates that the rates of secondary photolysis of CC and HQ occur extremely faster than the rates at which they are formed from phenol and further implies that the primary hydroxylation step is rate limiting for the combustion-synthesized TiO2 aided photodegradation of phenol. The degradation rates of salicylic acid and p-nitrophenol were also investigated, and the rates were higher for combustion-synthesized titania compared to Degussa P-25 TiO2. Superior activity of combustion-synthesized TiO2 toward photodegradation of organic compounds can be attributed to crystallinity, higher surface area, more surface hydroxyl groups, and optical absorption at higher wavelength. PMID:15046366

  9. A fractional-N frequency synthesizer for wireless sensor network nodes

    International Nuclear Information System (INIS)

    This paper presents a fractional-N frequency synthesizer for wireless sensor network (WSN) nodes. The proposed frequency synthesizer adopts a phase locked loop (PLL) based structure, which employs an LC voltage-controlled oscillator (VCO) with small VCO gain (KVCO) and frequency step (fstep) variations, a charge pump (CP) with current changing in proportion with the division ratio and a 20-bit ΔΣ modulator, etc. To realize constant KVCO and fstep, a novel capacitor sub-bands grouping method is proposed. The VCO sub-groups' sizes are arranged according to the maximal allowed KVCO variation of the system. Besides, a current mode logic divide-by-2 circuit with inside-loop buffers ensures the synthesizer generates I/Q quadrature signals robustly. This synthesizer is implemented in a 0.13 μm CMOS process. Measurement results show that the frequency synthesizer has a frequency span from 2.07 to 3.11 GHz and the typical phase noise is −86.34 dBc/Hz at 100 kHz offset and −114.17 dBc/Hz at 1 MHz offset with a loop bandwidth of about 200 kHz, which meet the WSN nodes' requirements. (semiconductor integrated circuits)

  10. Monitoring system for a synthesizer at SPring-8 synchrotron radiation facility and obtained results

    International Nuclear Information System (INIS)

    Beam orbit distortion in all dispersive sections was observed in the SPring-8 storage ring during beam commissioning. In order to confirm the stability of the radio frequency (RF) synthesizer, a monitoring system was developed. The system consists of a frequency counter referenced to a global positioning system (GPS) receiver. With this system, the output of the synthesizer, which uses an external 10 MHz-Rubidium atomic clock with the time accuracy of Δt/t=10−12, is correctly monitored with 11 digits absolute accuracy, verifying that the synthesizer works well. Measurement of the circumference of the SPring-8 storage ring reveals the effect of tidal forces and seasonal temperature variations on beam orbit. To maintain the center axis of photon radiation in experimental beam lines, a beam energy correction is carried out. The frequency of the RF synthesizer is changed every 5 min with 10-digit accuracy. This corresponds to an energy accuracy of ΔE/E=1.16×10−6. The monitoring system for the synthesizer and obtained results are described.

  11. A fractional-N frequency synthesizer for wireless sensor network nodes

    Science.gov (United States)

    Xiao, Ma; Zhankun, Du; Chang, Liu; Ke, Liu; Yuepeng, Yan; Tianchun, Ye

    2014-12-01

    This paper presents a fractional-N frequency synthesizer for wireless sensor network (WSN) nodes. The proposed frequency synthesizer adopts a phase locked loop (PLL) based structure, which employs an LC voltage-controlled oscillator (VCO) with small VCO gain (KVCO) and frequency step (fstep) variations, a charge pump (CP) with current changing in proportion with the division ratio and a 20-bit ΔΣ modulator, etc. To realize constant KVCO and fstep, a novel capacitor sub-bands grouping method is proposed. The VCO sub-groups' sizes are arranged according to the maximal allowed KVCO variation of the system. Besides, a current mode logic divide-by-2 circuit with inside-loop buffers ensures the synthesizer generates I/Q quadrature signals robustly. This synthesizer is implemented in a 0.13 μm CMOS process. Measurement results show that the frequency synthesizer has a frequency span from 2.07 to 3.11 GHz and the typical phase noise is -86.34 dBc/Hz at 100 kHz offset and -114.17 dBc/Hz at 1 MHz offset with a loop bandwidth of about 200 kHz, which meet the WSN nodes' requirements.

  12. A fully integrated frequency synthesizer for a dual-mode GPS and Compass receiver

    International Nuclear Information System (INIS)

    This paper presents a fully integrated frequency synthesizer for a dual-mode GPS and Compass receiver fabricated in a 0.13 μm CMOS technology. The frequency synthesizer is implemented with an on-chip symmetric inductor and an on-chip loop filter. A capacitance multiplying approach is proposed in the on-chip loop filter design for area-saving consideration. Pulse-swallow topology with a multistage noise shaping ΔΣ modulator is adopted in the frequency divider design. The synthesizer generates local oscillating signals at 1571.328 MHz and 1568.259 MHz with a 16.368 MHz reference clock by working in integer and fractional modes. Measurement results show that the phase noise of the synthesizer achieves −91.3 dBc/Hz and −117 dBc/Hz out of band at 100 kHz and 1 MHz frequency offset, separately. The proposed frequency synthesizer consumes 8.6 mA from a 1.2 V power supply and occupies an area of 0.92 mm2. (semiconductor integrated circuits)

  13. A facile one-pot method to synthesize ultrasmall core-shell superparamagnetic and upconversion nanoparticles.

    Science.gov (United States)

    Cheng, Qian; Guo, Hongxuan; Li, Yu; Liu, Shouxin; Sui, Jiehe; Cai, Wei

    2016-08-01

    Ultrasmall core-shell Fe3O4@NaYF4:Yb(3+)/Er(3+) nanoparticles with bifunctional properties have been successfully synthesized via one pot thermolysis method using oleylamine as both solvent and stabilizer. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), upconversion (UC) luminescence spectra and the physical properties measurement system (PPMS) were used to characterize the resulting samples. The synthesized samples have uniform morphology with a mean size of 14.5nm and excellent dispersibility. Moreover, these nanoparticles exhibit superparamagnetic behaviour with saturation magnetization of 8.45emμ/g and efficient up-conversion emission with a two-photon induced process when excited by a 980nm laser. These results suggest that the synthesized ultrasmall bifunctional nanoparticles may find many biomedical applications, such as clinical diagnosis and treatment of cancers. PMID:27135942

  14. Characterization of nano-crystalline ZrO2 synthesized via reactive plasma processing

    International Nuclear Information System (INIS)

    Highlights: → Direct conversion of micron-sized zirconium hydride powder to nanocrystalline ZrO2 powder. → The experimental approach uses reactive plasma processing technique. → The product has been characterized by various analytical tools to support the findings. - Abstract: Nano-crystalline ZrO2 powder has been synthesized via reactive plasma processing. The synthesized ZrO2 powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM) and FTIR spectroscopy. The synthesized powder consists of a mixture of tetragonal and monoclinic phases of zirconia. Average crystallite size calculated from the XRD pattern shows that particles with crystallite size 20 nm or less than 20 nm are in tetragonal phase, whereas particles greater than 20 nm are in the monoclinic phase. TEM results show that particles have spherical morphology with maximum percentage of particles distributed in a narrow size from about 15 nm to 30 nm.

  15. Multi-Band Multi-Tone Tunable Millimeter-Wave Frequency Synthesizer For Satellite Beacon Transmitter

    Science.gov (United States)

    Simons, Rainee N.; Wintucky, Edwin G.

    2016-01-01

    This paper presents the design and test results of a multi-band multi-tone tunable millimeter-wave frequency synthesizer, based on a solid-state frequency comb generator. The intended application of the synthesizer is in a satellite beacon transmitter for radio wave propagation studies at K-band (18 to 26.5 GHz), Q-band (37 to 42 GHz), and E-band (71 to 76 GHz). In addition, the architecture for a compact beacon transmitter, which includes the multi-tone synthesizer, polarizer, horn antenna, and power/control electronics, has been investigated for a notional space-to-ground radio wave propagation experiment payload on a small satellite. The above studies would enable the design of robust high throughput multi-Gbps data rate future space-to-ground satellite communication links.

  16. Enhanced antibacterial activity of zinc oxide nanoparticles synthesized using Petroselinum crispum extracts

    Science.gov (United States)

    Stan, Manuela; Popa, Adriana; Toloman, Dana; Silipas, Teofil-Danut; Vodnar, Dan Cristian; Katona, Gabriel

    2015-12-01

    The present contribution reports the synthesis of zinc oxide nanoparticles (ZnO NPs) using aqueous leaf and root extracts of Petroselinum crispum (parsley) and characterization of as-prepared samples. ZnO NPs are subjected to X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR) studies. The XRD studies reveal a hexagonal wurtzite structure without supplementary diffraction lines for all ZnO samples. TEM analysis shows that the particle size is influenced by the type of plant extract. The EPR spectra indicate the presence of Mn2+ ions in ZnO sample synthesized using P. crispum leaf extract, while zinc vacancy complexes and oxygen vacancies are evidenced in all analyzed samples. ZnO NPs synthesized using P. crispum extracts exhibit increased (2-16 times) antibacterial activity as compared to chemically synthesized ZnO NPs.

  17. Biogenic silver and gold nanoparticles synthesized using red ginseng root extract, and their applications.

    Science.gov (United States)

    Singh, Priyanka; Kim, Yeon Ju; Wang, Chao; Mathiyalagan, Ramya; El-Agamy Farh, Mohamed; Yang, Deok Chun

    2016-05-01

    In the present study, we report a green methodology for the synthesis of silver and gold nanoparticles, using the root extract of the herbal medicinal plant Korean red ginseng. The silver and gold nanoparticles were synthesized within 1 h and 10 min respectively. The nanoparticles generated were not aggregated, and remained stable for a long time, which suggests the nature of nanoparticles. The phytochemicals and ginsenosides present in the root extract assist in reducing and stabilizing the synthesized nanoparticles. The red ginseng root extract-generated silver nanoparticles exhibit antimicrobial activity against pathogenic microorganisms including Vibrio parahaemolyticus, Staphylococcus aureus, Bacillus cereus, and Candida albicans. In addition, the silver nanoparticles exhibit biofilm degrading activity against S. aureus and Pseudomonas aeruginosa. Thus, the present study opens up a new possibility of synthesizing silver and gold nanoparticles in a green and rapid manner using Korean red ginseng root extract, and explores their biomedical applications. PMID:25706249

  18. Enhanced antibacterial activity of zinc oxide nanoparticles synthesized using Petroselinum crispum extracts

    Energy Technology Data Exchange (ETDEWEB)

    Stan, Manuela, E-mail: manuela.stan@itim-cj.ro; Popa, Adriana; Toloman, Dana; Silipas, Teofil-Danut [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat, 400293 Cluj-Napoca (Romania); Vodnar, Dan Cristian [University of Agricultural Sciences and Veterinary Medicine, Department of Food Science and Technology, 3-5 Manastur Street, 400372 Cluj-Napoca (Romania); Katona, Gabriel [Babes-Bolyai University, Faculty of Chemistry and Chemical Engineering, 11 Arany Janos Street, 400028 Cluj-Napoca (Romania)

    2015-12-23

    The present contribution reports the synthesis of zinc oxide nanoparticles (ZnO NPs) using aqueous leaf and root extracts of Petroselinum crispum (parsley) and characterization of as-prepared samples. ZnO NPs are subjected to X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR) studies. The XRD studies reveal a hexagonal wurtzite structure without supplementary diffraction lines for all ZnO samples. TEM analysis shows that the particle size is influenced by the type of plant extract. The EPR spectra indicate the presence of Mn{sup 2+} ions in ZnO sample synthesized using P. crispum leaf extract, while zinc vacancy complexes and oxygen vacancies are evidenced in all analyzed samples. ZnO NPs synthesized using P. crispum extracts exhibit increased (2-16 times) antibacterial activity as compared to chemically synthesized ZnO NPs.

  19. Modifying the composition of hydrogen-terminated silicon nanoparticles synthesized in a nonthermal rf plasma

    International Nuclear Information System (INIS)

    Hydrogen-terminated silicon nanoparticles were synthesized over a broad range of conditions in a continuous flow, nonthermal rf plasma. The effects of three operating parameters--rf power, reactor pressure, and hydrogen flow rate--were examined in terms of their effects on particle crystallinity, size, and surface composition. Silicon-hydrogen composition was characterized in situ by Fourier transform infrared spectrometry, and particle structural morphology was examined with a transmission electron microscope. Amorphous or crystalline particles could be synthesized by appropriately adjusting the operating parameters. Over the majority of settings examined, the minimum power required to produce discrete crystalline particles was ∼20-30 W. Depending on the parameter settings, particles also exhibited hydrogen coverage ranging from predominantly monohydride (SiH) functional groups to more complex compositions of higher hydrides. Particles with the highest proportion of surface SiH bonds were consistently synthesized in the smallest diameter (4 mm i.d.) tube reactor.

  20. Trap-induced photoresponse of solution-synthesized MoS2

    Science.gov (United States)

    Lee, Youngbin; Yang, Jaehyun; Lee, Dain; Kim, Yong-Hoon; Park, Jin-Hong; Kim, Hyoungsub; Cho, Jeong Ho

    2016-04-01

    We investigated, for the first time, the photoresponse characteristics of solution-synthesized MoS2 phototransistors. The photoresponse of the solution-synthesized MoS2 phototransistor was solely determined by the interactions of the photogenerated charge carriers with the surface adsorbates and the interface trap sites. Instead of contributing to the photocurrent, the illumination-generated electron-hole pairs were captured in the trap sites (surface and interface sites) due to the low carrier mobility of the solution-synthesized MoS2. The photogenerated holes discharged ions (oxygen and/or water) adsorbed onto the MoS2 surface and were released as neutral molecules. At the same time, the photogenerated electrons filled the traps present at the interface with the underlying substrate during their transport to the drain electrode. The filled trap sites significantly relieved the band bending near the surface region, which resulted in both a negative shift in the turn-on voltage and an increase in the photocurrent. The time-dependent dynamics of the solution-synthesized MoS2 phototransistors revealed persistent photoconductance due to the trapped electrons at the interface. The photoconductance was recovered by applying a short positive gate pulse. The instantaneous discharge of the trapped electrons dramatically reduced the relaxation time to less than 20 ms. This study provides an important clue to understanding the photoresponses of various optoelectronic devices prepared using solution-synthesized two-dimensional nanomaterials.We investigated, for the first time, the photoresponse characteristics of solution-synthesized MoS2 phototransistors. The photoresponse of the solution-synthesized MoS2 phototransistor was solely determined by the interactions of the photogenerated charge carriers with the surface adsorbates and the interface trap sites. Instead of contributing to the photocurrent, the illumination-generated electron-hole pairs were captured in the trap

  1. Enhanced antibacterial activity of zinc oxide nanoparticles synthesized using Petroselinum crispum extracts

    International Nuclear Information System (INIS)

    The present contribution reports the synthesis of zinc oxide nanoparticles (ZnO NPs) using aqueous leaf and root extracts of Petroselinum crispum (parsley) and characterization of as-prepared samples. ZnO NPs are subjected to X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR) studies. The XRD studies reveal a hexagonal wurtzite structure without supplementary diffraction lines for all ZnO samples. TEM analysis shows that the particle size is influenced by the type of plant extract. The EPR spectra indicate the presence of Mn2+ ions in ZnO sample synthesized using P. crispum leaf extract, while zinc vacancy complexes and oxygen vacancies are evidenced in all analyzed samples. ZnO NPs synthesized using P. crispum extracts exhibit increased (2-16 times) antibacterial activity as compared to chemically synthesized ZnO NPs

  2. Supercontinuum Comb Generation Using Optical Pulse Synthesizer and Highly Nonlinear Dispersion-Shifted Fiber

    Science.gov (United States)

    Choi, Samuel; Tamura, Naoyuki; Kashiwagi, Ken; Shioda, Tatsutoshi; Tanaka, Yosuke; Kurokawa, Takashi

    2009-09-01

    We propose a novel supercontinuum (SC) generation technology using an optical pulse synthesizer and highly nonlinear dispersion-shifted fiber. The optical pulse synthesizer enables us to reshape seed pulses optimized for broadband SC generation. 25.0 and 12.5 GHz SC combs were successfully generated by propagating synthesized seed pulses in the highly nonlinear fiber. We investigated how seed pulse conditions including shape, peak power, repetition rate, and center wavelength affect SC spectral bandwidth. We also evaluated interferometric signal waveforms from a Michelson interferometer using the generated SC comb as the light source. Interferometric peak width improved to 35.5 µm when peak power reached 7.9 W for the Gaussian pulse-based SC comb. Numerical simulation results almost agreed with experimental results. The difference between SC combs generated from Gaussian and sech2 pulses was confirmed by the simulations.

  3. Toluene-sensing properties of In2O3 nanotubes synthesized by electrospinning

    International Nuclear Information System (INIS)

    The pristine In2O3 nanotubes were synthesized by electrospinning and subsequent calcination. Scanning electron microscope, X-ray powder diffraction and transmission electron micrograph were employed to analyze the morphology and crystal structure of the as-synthesized nanotubes. Gas-sensing properties of the as-synthesized In2O3 nanotubes were investigated by exposing the corresponding sensors to toluene, acetone, ethanol, formaldehyde, ammonia and carbon monoxide at 340 °C. The results show that the gas sensor possesses a good selectivity to toluene at 340 °C. The response of the In2O3 nanotube gas sensor to 40 ppm is about 5.88. The response and recovery times are about 3 s and 17 s, respectively. (semiconductor devices)

  4. Microwave, sonochemical and combustion synthesized CuO nanostructures and their electrical and bactericidal properties

    International Nuclear Information System (INIS)

    Highlights: •CuO nanoleaves synthesized by CTAB-assisted hydrothermal method. •CuO nanodiscs synthesized by CTAB-assisted sonochemical method. •Combustion synthesized CuO is highly porous. •Synthetic method and morphology influence CuO bactericidal activity. -- Abstract: Cetyltrimethylammonium bromide (CTAB)-assisted microwave synthesis of CuO provides nanoleaves and in the absence of CTAB the shape of CuO is irregular. Sonochemical synthesis of CuO using CTAB gives nanodiscs whereas irregularly shaped flake-like structure is obtained without CTAB. Combustion synthesized CuO is highly porous with innumerable large holes. CTAB does not provide any structure in combustion synthesis. Transmission electron micrographs (TEM) display the constituent nanoparticles of microwave and sonochemically synthesized CuO. The powder X-ray diffractogram (XRD) shows the sample obtained by sonochemical method in the absence of CTAB as a mixture of monoclinic CuO, cubic Cu2O, and orthorhombic Cu(OH)2. But the rest of the samples are pure CuO in monoclinic phase. The selected area electron diffractograms (SAED) of the microwave and sonochemically synthesized samples, in the presence as well as in the absence of CTAB, confirm the monoclinic phase of CuO and indicates the presence of amorphous CuO in traces. All the samples are characteristic of Fourier Transform infrared (FT-IR) Cu–O stretching frequencies. The method of synthesis and also the morphology influence the electrical properties as well as the bactericidal activity of CuO

  5. Microwave, sonochemical and combustion synthesized CuO nanostructures and their electrical and bactericidal properties

    Energy Technology Data Exchange (ETDEWEB)

    Karunakaran, C., E-mail: karunakaranc@rediffmail.com; Manikandan, G.; Gomathisankar, P.

    2013-12-15

    Highlights: •CuO nanoleaves synthesized by CTAB-assisted hydrothermal method. •CuO nanodiscs synthesized by CTAB-assisted sonochemical method. •Combustion synthesized CuO is highly porous. •Synthetic method and morphology influence CuO bactericidal activity. -- Abstract: Cetyltrimethylammonium bromide (CTAB)-assisted microwave synthesis of CuO provides nanoleaves and in the absence of CTAB the shape of CuO is irregular. Sonochemical synthesis of CuO using CTAB gives nanodiscs whereas irregularly shaped flake-like structure is obtained without CTAB. Combustion synthesized CuO is highly porous with innumerable large holes. CTAB does not provide any structure in combustion synthesis. Transmission electron micrographs (TEM) display the constituent nanoparticles of microwave and sonochemically synthesized CuO. The powder X-ray diffractogram (XRD) shows the sample obtained by sonochemical method in the absence of CTAB as a mixture of monoclinic CuO, cubic Cu{sub 2}O, and orthorhombic Cu(OH){sub 2}. But the rest of the samples are pure CuO in monoclinic phase. The selected area electron diffractograms (SAED) of the microwave and sonochemically synthesized samples, in the presence as well as in the absence of CTAB, confirm the monoclinic phase of CuO and indicates the presence of amorphous CuO in traces. All the samples are characteristic of Fourier Transform infrared (FT-IR) Cu–O stretching frequencies. The method of synthesis and also the morphology influence the electrical properties as well as the bactericidal activity of CuO.

  6. Antibacterial Activity and Global Reactivity Descriptors of Some Newly Synthesized Unsymmetrical Sulfamides

    Directory of Open Access Journals (Sweden)

    Amel Bendjeddou

    2016-05-01

    Full Text Available In the present study a series of unsymmetric linear sulfamides (1-9 starting from a primary amine were synthesized and their structures were confirmed by elemental analyses, mass spectrometry and 1H NMR techniques. All the synthesized compounds were screened for their antibacterial activities by both disc diffusion and minimal inhibition concentration (MIC methods. Frontier molecular orbital (FMO analysis and global reactivity descriptors have been performed using the density functional theory (DFT with the B3LYP functional. The results indicated that these derivatives, depending of their substituted radical, bring about an improvement in the bacterial activity.

  7. Chemical and biochemical activities of sonochemically synthesized poly(N-isopropyl acrylamide)/silica nanocomposite

    Science.gov (United States)

    Chowdhury, Pranesh; Saha, Swadhin Kr; Guha, Arun; Saha, Samar Kr

    2012-11-01

    Poly(N-isopropyl acrylamide) (PNIPA) grafted mesoporous silica nanoparticles (MPSNP) leading to novel inorganic/organic core-shell nanocomposite has been synthesized sonochemically in an aqueous medium without additives like cross-linker, hydrophobic agent, organic solvent. The colloidal stability of MPSNP is enhanced significantly due to encapsulation of the polymer. The composites are characterized by TEM, FTIR and TGA. The chemical and biochemical activities of the sonochemically synthesized materials have been studied in the light of reaction with acid-base, protein adsorption, antimicrobial activity, biocompatibility and nonthrombogenic property. Advantages of sonochemical synthesis compared to other techniques have been evaluated.

  8. Four Proteins Synthesized in Response to Deoxyribonucleic Acid Damage in Micrococcus Radiodurans

    DEFF Research Database (Denmark)

    Hansen, M. T.

    1980-01-01

    Four proteins, alpha beta, gamma, and delta, preferentially synthesized in ultraviolet light-treated cells of Micrococcus radiodurans, were characterized in terms of their molecular weights and isoelectric points. Within the sublethal-dose range, the differential rate of synthesis for these...... proteins increased linearly with the inducing UV dose. The degree of induction reached 100-fold, and the most abundant protein beta, amounted to approximately 2% of the total newly synthesized protein after irradiation. Damage caused by ionizing radiation or by treatment with mitomycin C also provoked the...

  9. The study of CdSe colloidal quantum dots synthesized in aqueous and organic media

    International Nuclear Information System (INIS)

    The samples of CdSe colloidal quantum dots (CQDs) synthesized in aqueous and organic media are studied. The possibility of luminescence peak position control depending on nanoparticle growth process is demonstrated. The samples synthesized in organic medium revealed the luminescence color variation effect with nanoparticle growth. The relation of this effect with processes of nucleation and defect formation in nanoparticles is considered. The CQDs of CdSe coated with CdS shell are fabricated. The use of inorganic shell can provide a double increase of the luminescence quantum yield

  10. Glycerol Containing Triacetylborate Mediated Syntheses of Novel 2-Heterostyryl Benzimidazole Derivatives: A Green Approach

    Directory of Open Access Journals (Sweden)

    Ashok Kumar Taduri

    2014-01-01

    Full Text Available A very simple, mild, efficient, and novel green methodology has been developed for the syntheses of some 2-hetero/styryl-benzimidazoles. Title compounds were synthesized by the condensation of o-phenylenediamine with cinnamic acids at 150–180°C for 5-6 h using glycerol containing triacetylborate (10–20 mol% as the reaction medium. In an alternative approach, condensation of 2-methylbenzimidazole derivatives with aromatic aldehydes was done using glycerol containing triacetylborate (10–20 mol% as the reaction medium.

  11. A fractional-N frequency synthesizer for WCDMA/Bluetooth/ZigBee applications

    International Nuclear Information System (INIS)

    A triple-mode fractional-N frequency synthesizer with a noise-filter voltage controlled oscillator (VCO) for WCDMA/Bluetooth/ZigBee applications has been implemented in 0.18-μm RF-CMOS technology. The proposed synthesizer achieves a good phase noise lower than -80 dBc/Hz in band and -115 dBc/Hz-1 MHz for the three modes, and only draws 21 mA from a 1.8 V supply. It has a high hardware sharing and a small size, only 1.5 x 1.4 mm2. The system architecture, circuit design, and measured results are also presented.

  12. Potentiometric study of polyaniline film synthesized with various dopants and composite-dopant: A comparative study

    Indian Academy of Sciences (India)

    P D Gaikwad; D J Shirale; V K Gade; P A Savale; K P Kakde; H J Kharat; M D Shirsat

    2006-08-01

    The potentiometric study of polyaniline (PANI) film synthesized with dopants viz. polyvinyl sulfonic acid (PVS), -toluene sulfonic acid (TS), dodecyl benzene sulfonic acid (DBS) and composite-dopants viz. PVS–TS and PVS–DBS, has been carried out. The synthesized PANI films were characterized by electrochemical technique, UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and conductivity measurement. It was found that the PANI doped with PVS gives good electrochemical properties, conductivity as well as surface morphology as compared to TS and DBS, whereas in composite dopants the PANI doped with PVS–TS gives good polymer matrix as compared to PVS–DBS.

  13. Polyvinylpyrrolidone adsorption effects on the morphologies of synthesized platinum particles and its catalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Ooi, Mahayatun Dayana Johan [Nano - Optoelectronic Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800, Minden, Pulau Pinang (Malaysia); Aziz, Azlan Abdul [Nano - Optoelectronic Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800, Minden, Pulau Pinang (Malaysia); Nanobiotechnology Research and Innovation (NanoBRI), INFORMM, Universiti Sains Malaysia, 11800, Minden, Pulau Pinang (Malaysia)

    2015-04-24

    Flower-like Platinum micro-structures were synthesized from different concentration of the PVP using solvothermal method. At 5.0×10{sup −3} mmol of PVP, well-defined flower-like pattern consists of triangular petals radiating from the centre were produced whereas larger flower network developed at higher PVP concentration. High degree of crystallinity was obtained upon each increment of PVP. The well defined flower like pattern synthesized using 5.0×10{sup −3} mmol PVP exhibit the highest catalytic activity and stability towards electro-oxidation of formic acid.

  14. Polyvinylpyrrolidone adsorption effects on the morphologies of synthesized platinum particles and its catalytic activity

    Science.gov (United States)

    Ooi, Mahayatun Dayana Johan; Aziz, Azlan Abdul

    2015-04-01

    Flower-like Platinum micro-structures were synthesized from different concentration of the PVP using solvothermal method. At 5.0×10-3 mmol of PVP, well-defined flower-like pattern consists of triangular petals radiating from the centre were produced whereas larger flower network developed at higher PVP concentration. High degree of crystallinity was obtained upon each increment of PVP. The well defined flower like pattern synthesized using 5.0×10-3 mmol PVP exhibit the highest catalytic activity and stability towards electro-oxidation of formic acid.

  15. Study of as-synthesized and calcined hydrocalumites as possible antacid agents

    Indian Academy of Sciences (India)

    Carlos F Linares; Freddy Ocanto; Pablo Bretto; Maricela Monsalve

    2014-06-01

    A hydrocalumite-type solid was synthesized by the homogeneous co-precipitation method by using Ca and Al nitrate solutions in a basic medium (NaOH). This solid was calcined at 700 and 900 °C, respectively. Then, solids were characterized by X-ray diffraction, FT–IR spectroscopy and BET surface area measurements. Finally, these solids were tested as antacids by using a synthetic gastric juice. Results showed that calcined samples were able to neutralize the synthetic gastric juice in more extension as an as-synthesized hydrocalumite; however, the last solid showed better conditions as a potential antacid.

  16. First-principles calculations of a high-pressure synthesized compound PtC

    OpenAIRE

    Li, L. Y.; Yu, W; Jin, C. Q.

    2005-01-01

    First-principles density-functional method is used to study the recently high-pressure synthesized compound PtC. It is confirmed by our calculations that the platinum carbide has a zinc-blende ground-state phase at zero pressure and the rock-salt structure is a high-pressure phase. The theoretical transition pressure from zinc-blende to rock-salt is determined to be 52GPa. Furthermore, our calculation shows the possibility that the experimentally synthesized PtC by Ono et al. under high press...

  17. Database of open-framework aluminophosphate syntheses:introduction and application (Ⅰ)

    Institute of Scientific and Technical Information of China (English)

    YAN Yan; LI JiYang; QI Miao; ZHANG Xiao; YU JiHong; XU RuRen

    2009-01-01

    The database of open-framework aluminophosphate (AIPO) syntheses has been established,which Includes about 1600 synthetic records.Data analysis has been done on the basis of the framework composition,structure dimension,pore ring,and organic template.This database will serve as useful guidance for the rational synthesis of microporous functional materials.

  18. A reconstruction strategy to synthesize mesoporous SAPO molecular sieve single crystals with high MTO catalytic activity.

    Science.gov (United States)

    Wang, Chan; Yang, Miao; Li, Mingrun; Xu, Shutao; Yang, Yue; Tian, Peng; Liu, Zhongmin

    2016-05-11

    Mesoporous SAPO-34 single crystals with tunable porosity and Si content have been fast synthesized within 4 hours by a reconstruction strategy, which show excellent hydrothermal stability and MTO catalytic activity. This new strategy is further proven to be applicable to prepare other mesoporous SAPO molecular sieve single crystals. PMID:27101359

  19. High quantum yield ZnO quantum dots synthesizing via an ultrasonication microreactor method.

    Science.gov (United States)

    Yang, Weimin; Yang, Huafang; Ding, Wenhao; Zhang, Bing; Zhang, Le; Wang, Lixi; Yu, Mingxun; Zhang, Qitu

    2016-11-01

    Green emission ZnO quantum dots were synthesized by an ultrasonic microreactor. Ultrasonic radiation brought bubbles through ultrasonic cavitation. These bubbles built microreactor inside the microreactor. The photoluminescence properties of ZnO quantum dots synthesized with different flow rate, ultrasonic power and temperature were discussed. Flow rate, ultrasonic power and temperature would influence the type and quantity of defects in ZnO quantum dots. The sizes of ZnO quantum dots would be controlled by those conditions as well. Flow rate affected the reaction time. With the increasing of flow rate, the sizes of ZnO quantum dots decreased and the quantum yields first increased then decreased. Ultrasonic power changed the ultrasonic cavitation intensity, which affected the reaction energy and the separation of the solution. With the increasing of ultrasonic power, sizes of ZnO quantum dots first decreased then increased, while the quantum yields kept increasing. The effect of ultrasonic temperature on the photoluminescence properties of ZnO quantum dots was influenced by the flow rate. Different flow rate related to opposite changing trend. Moreover, the quantum yields of ZnO QDs synthesized by ultrasonic microreactor could reach 64.7%, which is higher than those synthesized only under ultrasonic radiation or only by microreactor. PMID:27245962

  20. Characterization of glycolipids synthesized in an identified neuron of Aplysia californica

    International Nuclear Information System (INIS)

    Because radioactive precursors can be injected directly into the cell body or axon of R2, a giant, identified neuron of the Aplysia abdominal ganglion, it was possible to show that glycolipid is synthesized in the cell body, inserted into membranes along with glycoprotein, and then exported into the axon within organelles that are moved by fast axonal transport. After intrasomatic injection of N-[3H]-acetyl-D-galactosamine, five major 3H-glycolipids were identified using thin layer polysilicic acid glass fiber chromatography. At least two of the lipids are negatively charged. Analysis of 32P-labeled lipid from the abdominal ganglion revealed the presence of 2-aminoethylphosphonate, indicating that these polar substances are sphingophosphonoglycolipids. The major 3H-glycolipids synthesized in R2 are similar to a family of phospholipids isolated from the skin of A. kurodai. Since sialic acid is absent in Aplysia as in other invertebrates, these polar glycolipids may function like gangliosides in vertebrates. The polar 3H-glycolipids are synthesized and incorporated into intracytoplasmic membranes solely in the cell body. Direct injection of the labeled sugar into the axon revealed no local synthesis or exchange of glycolipid. Moreover, there was no indication for transfer from glial cells into axoplasm. Although the incorporation of N-[3H]-acetyl-D-galactosamine into glycolipid is not affected by anisomycin, an effective inhibitor of protein synthesis, the export into the axon of membranes containing the newly synthesized lipid is completely blocked by the drug

  1. Molybdenum carbide-carbon nanocomposites synthesized from a reactive template for electrochemical hydrogen evolution

    KAUST Repository

    Alhajri, Nawal Saad

    2014-01-01

    Molybdenum carbide nanocrystals (Mo2C) with sizes ranging from 3 to 20 nm were synthesized within a carbon matrix starting from a mesoporous graphitic carbon nitride (mpg-C3N4) template with confined pores. A molybdenum carbide phase (Mo2C) with a hexagonal structure was formed using a novel synthetic method involving the reaction of a molybdenum precursor with the carbon residue originating from C3N4 under nitrogen at various temperatures. The synthesized nanocomposites were characterized using powder X-ray diffraction (XRD), temperature-programmed reaction with mass spectroscopy (MS), CHN elemental analyses, thermogravimetric analyses (TGA), nitrogen sorption, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The results indicated that the synthesized samples have different surface structures and compositions, which are accordingly expected to exhibit different electrocatalytic activities toward the hydrogen evolution reaction (HER). Electrochemical measurements demonstrated that the sample synthesized at 1323 K exhibited the highest and most stable HER current in acidic media, with an onset potential of -100 mV vs. RHE, among the samples prepared in this study. This result is attributed to the sufficiently small particle size (∼8 nm on average) and accordingly high surface area (308 m2 g-1), with less oxidized surface entrapped within the graphitized carbon matrix. © 2014 the Partner Organisations.

  2. Chemoselective Reactions of Citral: Green Syntheses of Natural Perfumes for the Undergraduate Organic Laboratory

    Science.gov (United States)

    Cunningham, Anna D.; Ham, Eun Y.; Vosburg, David A.

    2011-01-01

    Chemoselectivity is a central concept in organic synthesis and may be readily appreciated in the context of the fragrant, polyfunctional natural product citral. We describe three single-step reactions students may perform on citral to synthesize other natural perfumes: citronellal, geraniol, nerol, or epoxycitral. Each of the reactions uses a…

  3. PbO networks composed of single crystalline nanosheets synthesized by a facile chemical precipitation method

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Synthesis of PbO networks through a simple chemical precipitation route. • The synthesis method is rapid and low-cost. • Each network is composed of single crystalline PbO nanosheets. • A possible growth mechanism is proposed for synthesized PbO networks. - Abstract: For the field of energy storage, nanostructured lead oxide (PbO) shows immense potential for increased specific energy and deep discharge for lead acid battery technologies. In this work, PbO networks composed of single crystalline nanosheets were synthesized utilizing a simple, low cost and rapid chemical precipitation method. The PbO networks were prepared in a single reaction vessel from starting reagents of lead acetate dehydrate, ammonium hydroxide and deionized water. Lead acetate dehydrate was chosen as a reagent, as opposed to lead nitrate, to eliminate the possibility of nitrate contamination of the final product. X-ray diffraction (XRD) analysis, high resolution scanning electron microscopy (HRSEM) and high resolution transmission electron microscopy (HRTEM) analysis were used to characterize the synthesized PbO networks. The reproducible method described herein synthesized pure β-PbO (massicot) powders, with no byproducts. A possible formation mechanism for these PbO networks is proposed. The growth is found to proceed predominately in the 〈1 1 1〉 and 〈2 0 0〉 directions while being limited in the 〈0 1 1〉 direction

  4. WICS: A Model of Positive Educational Leadership Comprising Wisdom, Intelligence, and Creativity Synthesized

    Science.gov (United States)

    Sternberg, Robert J.

    2005-01-01

    Who are the people who become positive educational leaders? This essay presents WICS as a model of positive educational leadership. WICS stands for "w"isdom, "i"ntelligence, "c"reativity, "s"ynthesized. Each of these elements is asserted to constitute one of the elements of educational leadership. Regrettably, our society is organized around a…

  5. Wisdom, Intelligence, and Creativity Synthesized: A New Model for Liberal Education

    Science.gov (United States)

    Sternberg, Robert J.

    2009-01-01

    WICS (Wisdom, Intelligence, and Creativity Synthesized) provides a unified model of liberal education for admissions, instruction, and assessment that can be used at any level and for any subject matter. One advantage of WICS is that it goes beyond more traditional models that emphasize memory and analytical learning and, as a result, enables all…

  6. CATALYTIC ACTIVITIES OF RARE-EARTH CALIXARENE COMPLEXES IN POLYMER SYNTHESES

    Institute of Scientific and Technical Information of China (English)

    Zhi-quan Shen

    2005-01-01

    The studies of our group on the catalytic activities of rare earth calixarene complexes in polymer syntheses are reviewed. Rare earth calixarene complexes are effect catalysts for the polymerizations of butadiene, isoprene, ethylene,styrene, propylene oxide, styrene oxide, trimethylene carbonate and 2,2-dimethyl-trimethylene carbonate.

  7. Organisation of organic agriculture research in Denmark - background, use of knowledge syntheses, analysis of results

    OpenAIRE

    Rasmussen, Ilse A.

    2014-01-01

    The presentation gives the history and background of ICROFS (International Centre for Research in Organic Food Systems, previously DARCOF), introduces the concept of knowledge syntheses and reports on the analysis of results and impact of the first 15 years of research in organic agriculture in Denmark

  8. A power scalable PLL frequency synthesizer for high-speed Δ—Σ ADC

    International Nuclear Information System (INIS)

    A 35–130 MHz/300–360 MHz phase-locked loop frequency synthesizer for Δ—Σ analog-to-digital converter (ADC) in 65 nm CMOS is presented. The frequency synthesizer can work in low phase-noise mode (300–360 MHz) or in low-power mode (35–130 MHz) to satisfy the ADC's requirements. To switch between these two modes, a high frequency GHz LC VCO followed by a divided-by-four frequency divider and a low frequency ring VCO followed by a divided-by-two frequency divider are integrated on-chip. The measured results show that the frequency synthesizer achieves a phase-noise of −132 dBc/Hz at 1 MHz offset and an integrated RMS jitter of 1.12 ps with 1.74 mW power consumption from a 1.2 V power supply in low phase-noise mode. In low-power mode, the frequency synthesizer achieves a phase-noise of −112 dBc/Hz at 1 MHz offset and an integrated RMS jitter of 7.23 ps with 0.92 mW power consumption from a 1.2 V power supply. (semiconductor integrated circuits)

  9. CATALYTIC AND ADSORPTION PROPERTIES OF Al- AND Ti-MCM-41 SYNTHESIZED AT ROOM TEMPERATURE

    OpenAIRE

    Silva, Tiago N.; Lopes, José Madeira; Ribeiro, Fernando Ramôa; Carrott, Manuela Ribeiro; Galacho, Cristina; Sousa, Maria José; Carrott, Peter

    2002-01-01

    Aluminosilicate and titanosilicate MCM-41 were synthesized using a room temperature method. A preliminary catalytic evaluation was performed in the promotion of the 1-butene double bond isomerization, which was successful in probing differences in the acidity of the samples prepared.

  10. Structural, morphological and spectroscopic properties of Eu3+-doped rare earth fluorides synthesized by the hydrothermalmethod

    International Nuclear Information System (INIS)

    Rare earth fluorides (REF3, RE=Y, La, Gd or Yb) doped with 5% of Eu3+ ions were synthesized via the hydrothermal method and their physicochemical properties were compared. The synthesis was carried out in an aqueous medium at elevated pressure and temperature. The reaction was performed in situ, with use of NaBF4 as a source of fluoride ions. Structural and morphological properties of obtained nanophosphors were characterized with the use of powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. Synthesized products were nanocrystalline with hexagonal or orthorhombic crystal structures. They showed different morphology, from nanoplates to nanorings, depending on the used REF3 fluoride as the host for the Eu3+ ions. The elemental composition was confirmed by the energy-dispersive X-ray spectroscopy (EDX) results. Spectroscopic properties were investigated by measuring the excitation and emission spectra. Also luminescence lifetimes were determined. The synthesized materials showed bright red luminescence, due to the presence of Eu3+ ions in their structure. - Graphical abstract: Luminescence spectra of the REF3:Eu3+ (RE=Y, La, Gd and Yb) fluorides and their TEM images as background. Highlights: ► Nanocrystalline fluorides were synthesized using modified hydrothermal method. ► Structural and morphological properties of in situ prepared nanomaterials were studied. ► Luminescence properties of REF3:Eu3+ (RE=Y, La, Gd, Yb) were compared and investigated

  11. Thermal stability of 5083 Al synthesized by reactive atomization and deposition

    International Nuclear Information System (INIS)

    Vickers microhardness and tensile properties are measured for the extruded and annealed 5083 Al synthesized by reactive atomization and deposition (RAD) and by N2 spray deposition (SDN). The results show a higher thermal stability for RAD 5083 Al compared to SDN 5083 Al, which is primarily attributed to the grain boundary pinning originating from fine MgO dispersoids

  12. Physically-synthesized gold nanoparticles containing multiple nanopores for enhanced photothermal conversion and photoacoustic imaging.

    Science.gov (United States)

    Park, Jisoo; Kang, Heesung; Kim, Young Heon; Lee, Sang-Won; Lee, Tae Geol; Wi, Jung-Sub

    2016-08-25

    Physically-synthesized gold nanoparticles having a narrow size distribution and containing multiple nanopores have been utilized as photothermal converters and imaging contrast agents. Nanopores within the gold nanoparticles make it possible to increase the light-absorption cross-section and consequently exhibit distinct improvements in photothermal conversion and photoacoustic imaging efficiencies. PMID:27527067

  13. Carbon-14 labelled nitrogen heterocycles; the syntheses of three phosphodiesterase inhibitors

    International Nuclear Information System (INIS)

    The syntheses of three heterocyclic phosphodiesterase inhibitors are described from a common radiolabelled precursor, namely 2-propoxybenzo[cyano-14C] nitrile. Conversion of the nitrile to the corresponding methyl ketone or amidine allows elaboration of the heterocycles radiolabelled within the ring systems. (Author)

  14. Four Proteins Synthesized in Response to Deoxyribonucleic Acid Damage in Micrococcus Radiodurans

    DEFF Research Database (Denmark)

    Hansen, M. T.

    1980-01-01

    proteins increased linearly with the inducing UV dose. The degree of induction reached 100-fold, and the most abundant protein beta, amounted to approximately 2% of the total newly synthesized protein after irradiation. Damage caused by ionizing radiation or by treatment with mitomycin C also provoked the...

  15. New method in synthesizing an optical active intermediate for (R,R)-formoterol

    Institute of Scientific and Technical Information of China (English)

    Wei Fan; Lei Chen; Li Hai; Yong Wu

    2008-01-01

    (R)-1-(4-Methoxyphenyl)propan-2-amine 2a, an optical active intermediate for (R,R)-formoterol, was synthesized from D-alanine in 65% overall yield by using a simple route, which contained protecting amino group, cyclization, coupling with Grignard reagent, reduction and deprotection.

  16. High-intensity attosecond high-order harmonic generation driven by a synthesized laser field

    International Nuclear Information System (INIS)

    The scheme of high-intensity attosecond high-order harmonic generation driven by a synthesized laser field is proposed. The synthesized laser field is obtained by an appropriate superposition of a few-cycle laser pulse and a relatively long pulse of several tens of femtoseconds. Calculated results show that the intensity of the attosecond high-order harmonic pulse in helium driven by the synthesized laser field with a 8.8x1013 W/cm2/5 fs laser pulse and a 3.51x1014 W/cm2/50 fs laser pulse is several orders of magnitude higher than that driven by a single 8.8x1013 W/cm2/5 fs laser pulse, and it is even stronger than that driven by a single 7.9x1014 W/cm2/5 fs laser pulse, although the single and the synthesized pulses have the same peak electric-field strength

  17. Anionic polymerization and polyhomologation: An ideal combination to synthesize polyethylene-based block copolymers

    KAUST Repository

    Zhang, H.

    2013-08-07

    A novel one-pot methodology combining anionic polymerization and polyhomologation, through a "bridge" molecule (BF3OEt 2), was developed for the synthesis of polyethylene (PE)-based block copolymers. The anionically synthesized macroanion reacts with the "bridge" molecule to afford a 3-arm star (trimacromolecular borane) which serves as an initiator for the polyhomologation. 2013 The Royal Society of Chemistry.

  18. Ruthenium-catalyzed C-H/N-O bond functionalization: green isoquinolone syntheses in water.

    OpenAIRE

    Ackermann, Lutz; Fenner, Sabine

    2011-01-01

    Ruthenium-catalyzed isoquinolone syntheses with ample scope were accomplished through carboxylate assistance in environmentally benign water as a reaction medium. The high chemoselectivity of the ruthenium(II) carboxylate complex also set the stage for the direct use of free hydroxamic acids for annulations of alkynes.

  19. Polymer coating comprising 2-methoxyethyl acrylate units synthesized by surface-initiated atom transfer radical polymerization

    DEFF Research Database (Denmark)

    2011-01-01

    Source: US2012184029A The present invention relates to preparation of a polymer coating comprising or consisting of polymer chains comprising or consisting of units of 2-methoxyethyl acrylate synthesized by Surface-Initiated Atom Transfer Radical Polymerization (SI ATRP) such as ARGET SI ATRP or...

  20. Benzene containing polyhydroxyalkanoates homo- and copolymers synthesized by genome edited Pseudomonas entomophila

    DEFF Research Database (Denmark)

    Shen, Rui; Cai, Longwei; Meng, Dechuan;

    2014-01-01

    Microbial synthesis of functional polymers has become increasingly important for industrial biotechnology. For the first time, it became possible to synthesize controllable composition of poly(3-hydroxyalkanoate) (P3HA) consisting of 3-hydroxydodecanoate (3HDD) and phenyl group on the side-chain ...

  1. Children's Responses to Computer-Synthesized Speech in Educational Media: Gender Consistency and Gender Similarity Effects

    Science.gov (United States)

    Lee, Kwan Min; Liao, Katharine; Ryu, Seoungho

    2007-01-01

    This study examines children's social responses to gender cues in synthesized speech in a computer-based instruction setting. Eighty 5th-grade elementary school children were randomly assigned to one of the conditions in a full-factorial 2 (participant gender) x 2 (voice gender) x 2 (content gender) experiment. Results show that children apply…

  2. Method for Synthesizing Metal Nanowires in Anodic Alumina Membranes Using Solid State Reduction

    Science.gov (United States)

    Martinez-Inesta, Maria M (Inventor); Feliciano, Jennie (Inventor); Quinones-Fontalvo, Leonel (Inventor)

    2016-01-01

    The invention proposes a novel method for the fabrication of regular arrays of MNWs using solid-state reduction (SSR). Using this method copper (Cu), silver (Ag), and palladium (Pd) nanowire (NWs) arrays were synthesized using anodic alumina membranes (AAMs) as templates. Depending on the metal loading used the NWs reached different diameters.

  3. Green, Enzymatic Syntheses of Divanillin and Diapocynin for the Organic, Biochemistry, or Advanced General Chemistry Laboratory

    Science.gov (United States)

    Nishimura, Rachel T.; Giammanco, Chiara H.; Vosburg, David A.

    2010-01-01

    Environmentally benign chemistry is an increasingly important topic both in the classroom and the laboratory. In this experiment, students synthesize divanillin from vanillin or diapocynin from apocynin, using horseradish peroxidase and hydrogen peroxide in water. The dimerized products form rapidly at ambient temperature and are isolated by…

  4. Database of open-framework aluminophosphate syntheses:introduction and application(Ⅰ)

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The database of open-framework aluminophosphate(AlPO) syntheses has been established,which includes about 1600 synthetic records.Data analysis has been done on the basis of the framework composition,structure dimension,pore ring,and organic template.This database will serve as useful guidance for the rational synthesis of microporous functional materials.

  5. Capability of resisting γ-ray irradiation and immobilization for simulated trivalent actinides on synthesized zircon

    International Nuclear Information System (INIS)

    In order to investigate zircon immobilization for trivalent actinides and its γ-ray irradiation stability, zircon was synthesized at 1 500 degree C for 22 h using ZrO2, SiO2 and Eu2O3(2.5%-10% in mole) powders as the starting materials and trivalent europium (Eu3+) as the simulacrum. Then, γ-ray irradiation experiment of the condensates was conducted. The phases, structure and surface morphology of the synthesized condensates and the corresponding irradiated condensates were characterized by X-ray diffraction (XRD), laser Raman microprobe (RMP) and scanning electron microscopy (SEM). The results indicate that the main phase of the synthesized condensates is zircon, and it still shows a high crystallinity although 2.5%-10% of Eu2O3 is added in the starting materials. With the increase of Eu2O3 in the starting materials, the metamict degree of the synthesized condensates is slightly increased. Zircon is still the main phase in the irradiated condensates though they are irradiated by 579.1 kGy of γ-ray. The crystallinity of irradiated samples is slightly weakened hence the degree of metamict slightly increased. (authors)

  6. Structural interpretation of chemically synthesized ZnO nanorod and its application in lithium ion battery

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • ZnO nanorods are synthesized at room temperature via a simple chemical route. • Growth direction of ZnO nanorods has been determined along 〈0 0 2〉. • ZnO nanorods constructed anode shows a high discharge capacity in first cycle. • It retains good reversible capacity compared to other ZnO morphologies. - Abstract: ZnO nanorods are synthesized at room temperature via a simple chemical route without using any template or capping agent and its importance is evaluated as a suitable candidate for anode material in lithium ion battery. Structural and microstructure characterizations of these nanorods are made by analyzing the X-ray diffraction data employing the Rietveld method of powder structure refinement. It reveals that the ZnO nanorods are grown up with a preferred orientation and elongated along 〈0 0 2〉. FESEM images reveal that these uniform cylindrical shaped nanorods are of different lengths and diameters. These synthesized ZnO nanorods are tested as an anode material for lithium ion batteries. The nano grain size of the ZnO rods results in less volume expansion and/or contraction during the alloying/de-alloying process and causes in good cyclability. In addition, synthesized ZnO nanorods deliver high charge/discharge capacities compared to other reported ZnO materials

  7. Structural interpretation of chemically synthesized ZnO nanorod and its application in lithium ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Samapti; Sain, Sumanta [Materials Science Division, Department of Physics, The University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India); Yoshio, Masaki [Advanced Research and Education Centre, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan); Kar, Tanusree [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, West Bengal (India); Gunawardhana, Nanda, E-mail: nandagunawardhana@pdn.ac.lk [International Research Centre, Senate Building, University of Peradeniya, Peradeniya 20400 (Sri Lanka); Pradhan, Swapan Kumar, E-mail: skpradhan@phys.buruniv.ac.in [Materials Science Division, Department of Physics, The University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India)

    2015-02-28

    Graphical abstract: - Highlights: • ZnO nanorods are synthesized at room temperature via a simple chemical route. • Growth direction of ZnO nanorods has been determined along 〈0 0 2〉. • ZnO nanorods constructed anode shows a high discharge capacity in first cycle. • It retains good reversible capacity compared to other ZnO morphologies. - Abstract: ZnO nanorods are synthesized at room temperature via a simple chemical route without using any template or capping agent and its importance is evaluated as a suitable candidate for anode material in lithium ion battery. Structural and microstructure characterizations of these nanorods are made by analyzing the X-ray diffraction data employing the Rietveld method of powder structure refinement. It reveals that the ZnO nanorods are grown up with a preferred orientation and elongated along 〈0 0 2〉. FESEM images reveal that these uniform cylindrical shaped nanorods are of different lengths and diameters. These synthesized ZnO nanorods are tested as an anode material for lithium ion batteries. The nano grain size of the ZnO rods results in less volume expansion and/or contraction during the alloying/de-alloying process and causes in good cyclability. In addition, synthesized ZnO nanorods deliver high charge/discharge capacities compared to other reported ZnO materials.

  8. Low noise frequency synthesizer with self-calibrated voltage controlled oscillator and accurate AFC algorithm

    International Nuclear Information System (INIS)

    A low noise phase locked loop (PLL) frequency synthesizer implemented in 65 nm CMOS technology is introduced. A VCO noise reduction method suited for short channel design is proposed to minimize PLL output phase noise. A self-calibrated voltage controlled oscillator is proposed in cooperation with the automatic frequency calibration circuit, whose accurate binary search algorithm helps reduce the VCO tuning curve coverage, which reduces the VCO noise contribution at PLL output phase noise. A low noise, charge pump is also introduced to extend the tuning voltage range of the proposed VCO, which further reduces its phase noise contribution. The frequency synthesizer generates 9.75–11.5 GHz high frequency wide band local oscillator (LO) carriers. Tested 11.5 GHz LO bears a phase noise of−104 dBc/Hz at 1 MHz frequency offset. The total power dissipation of the proposed frequency synthesizer is 48 mW. The area of the proposed frequency synthesizer is 0.3 mm2, including bias circuits and buffers. (semiconductor integrated circuits)

  9. Effect of Preparation Conditions on the Crystallinity of Chemically Synthesized BCNO Nanophosphor

    Institute of Scientific and Technical Information of China (English)

    Lakhwant Singh; Viblla Chopra

    2011-01-01

    The carbon based boron oxynitride (BCNO) phosphor was synthesized by solid state reaction between boric acid (H3BO3) and melamine (C3H6N6) in the molar ratios of 1:1 and 2:1 respectively at different temperatures up to 1400℃. The composition with molar ratios 1:1 of starting materials is found to be highly crystalline with an average particle size of 38 nm and the lattice constants a=b=0.251 nm and c=0.666 nm. The solid state reaction of boric acid and melamine in the composition 2:1 leads to the formation of compound in the semi-crystalline state under the same conditions of preparation, but its phase cannot be recognised. The X-ray diffraction (XRD) spectra, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images of BCNO compound confirm the phase, nanometre size and shape respectively of synthesized material. The photoluminescence (PL) spectra of the synthesized BCNO products reveals that the electronic structure of BCNO compound can be controlled by changing the molar ratios of starting materials and heating temperatures. These synthesized compounds are very interesting and important candidate materials for light emitter.

  10. Synthesizing mixed H2/H-infinity dynamic controller using evolutionary algorithms

    DEFF Research Database (Denmark)

    Pedersen, Gerulf; Langballe, A.S.; Wisniewski, Rafal

    2001-01-01

    This paper covers the design of an Evolutionary Algorithm (EA), which should be able to synthesize a mixed H2/H-infinity. It will be shown how a system can be expressed as Matrix Inequalities (MI) and these will then be used in the design of the EA. The main objective is to examine whether a mixed...

  11. Synthesizing multi-objective H2/H-infinity dynamic controller using evolutionary algorithms

    DEFF Research Database (Denmark)

    Pedersen, Gerulf; Langballe, A.S.; Wisniewski, Rafal

    This paper covers the design of an Evolutionary Algorithm (EA), which should be able to synthesize a mixed H2/H-infinity. It will be shown how a system can be expressed as Matrix Inequalities (MI) and these will then be used in the design of the EA. The main objective is to examine whether a mixed...

  12. Antibacterial and cytotoxic potential of silver nanoparticles synthesized using latex of Calotropis gigantea L.

    Science.gov (United States)

    Rajkuberan, Chandrasekaran; Sudha, Kannaiah; Sathishkumar, Gnanasekar; Sivaramakrishnan, Sivaperumal

    2015-02-01

    The present study aimed to synthesis silver nanoparticles (AgNPs) in a greener route using aqueous latex extract of Calotropis gigantea L. toward biomedical applications. Initially, synthesis of AgNPs was confirmed through UV-Vis spectroscopy which shows the surface plasmonic resonance peak (SPR) at 420 nm. Fourier transform infrared spectroscopy (FTIR) analysis provides clear evidence that protein fractions present in the latex extract act as reducing and stabilizing bio agents. Energy dispersive X-ray (EDAX) spectroscopy confirms the presence of silver as a major constituent element. X-ray diffractograms displays that the synthesized AgNPs were biphasic crystalline nature. Electron microscopic studies such as Field emission scanning electron microscopic (Fe-SEM) and Transmission electron microscope (TEM) reveals that synthesized AgNPs are spherical in shape with the size range between 5 and 30 nm. Further, crude latex aqueous extract and synthesized AgNPs were evaluated against different bacterial pathogens such as Bacillus cereus, Enterococci sp, Shigella sp, Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus aureus and Escherichia coli. Compared to the crude latex aqueous extract, biosynthesized AgNPs exhibits a remarkable antimicrobial activity. Likewise invitro anticancer study manifests the cytotoxicity value of synthesized AgNPs against tested HeLa cells. The output of this study clearly suggesting that biosynthesized AgNPs using latex of C. gigantea can be used as promising nanomaterial for therapeutic application in context with nanodrug formulation.

  13. Syntheses of micrometer-long Pt and Ag nanowires through SBA-15 templating

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyoung-Jae; Lee, Eun-Sun; Kwon, Young-Uk, E-mail: ywkwon@skku.edu [Sungkyunkwan University, Department of Chemistry, BK-21 School of Chemical Materials Sciences (Korea, Republic of)

    2012-12-15

    We synthesized Pt and Ag nanowires using a mesoporous silica, SBA-15, as templates. The obtained nanowires are a few micrometers ({approx}4 {mu}m) long and 7 nm in diameter. The nanowires are free from bundling and, thus, can be separated as single nanowires. The successful synthesis of such nanowires requires a few considerations. In general, SBA-15 has microchannels on the walls through which the mesopores are interconnected when synthesized at 100 Degree-Sign C or higher. We, therefore, synthesized SBA-15 at a low temperature (80 Degree-Sign C) to eliminate the microchannels. Impregnation of the metal precursors and reduction of them into metals forms metal particles outside the pores in addition to the desired metal nanowires inside the pores. Surface alkylation of SBA-15 prohibits the nucleation of metal on the external surface and exclusively forms the nanowires. Finally, the introduction of surface passivating agent, an alkylthiol, during the removal of the template keeps the nanowires from interacting with one another. The Pt and Ag nanowires so-synthesized were characterized by electron microscopy.

  14. Syntheses of monomers in the reaction of hexamethylolmelamine with 2-hydroxyethyl acrylate and their photocuring

    International Nuclear Information System (INIS)

    A process has been developed for the syntheses of monomers from 2-hydroxyethyl acrylate and hexamethylolmelamine. Their structure were identified by IR and sub 1H-NMR. The photocuring characteristics of these compound and properties of the UV-cured films have been studied

  15. Acaricidal activity of synthesized titanium dioxide nanoparticles using Calotropis gigantea against Rhipicephalus microplus and Haemaphysalis bispinosa

    Institute of Scientific and Technical Information of China (English)

    Sampath; Marimuthu; Abdul; Abdul; Rahuman; Chidambaram; Jayaseelan; Arivarasan; Vishnu; Kirthi; Thirunavukkarasu; Santhoshkumar; Kanayairam; Velayutham; Asokan; Bagavan; Chinnaperumal; Kamaraj; Gandhi; Elango; Moorthy; Iyappan; Chinnadurai; Siva; Loganathan; Karthik; Kokati; Venkata; Bhaskara; Rao

    2013-01-01

    Objective:To assess the acaricidal activity of titanium dioxide nanoparticles(TiO2 NPs)synthesized from flower aqueous extract of Calotropis gigantea(C.gigantea)against the larvae of Rhipicephalus(Boophilus)microplus[R.(B.)microplus]and the adult of Haemaphrysalis bispinosa(H.bispinosa).Methods:The lyophilized C.gigantea flower aqueous extract of 50 mg was added with 100 mL of TiO(OH2)(10 mM)and magnetically stirred for 6 h.Synthesized TiO2 NPs were characterized by X-ray diffraction(XRD).Fourier transform infrared spectroscopy(FTIR),Scanning electron microscopy(SEM),and Energy dispersive X-ray spectroscopy(EDX).The synthesised TiO2 NPs were tested against the larvae of R(B.)microplus and adult of H.bispinosa were exposed to filter paper impregnated method.Results:XRD confirmed the crystalline nature of the nanoparticles with the mean size of 10.52 nm.The functional groups for synthesized TiO2NPs were 1405.19,and 1053.45 cm-1for-NH2 bending,primary amines and amides and 1053.84and 1078.45 cm-1for C-O.SEM micrographs of the synthesized TiO2 NPs showed the aggregated and spherical in shape.The maximum efficacy was observed in the aqueous flower extract of C.gigantea and synthesized TiO2 NPs against R.(B.)microplus(LC50=24.63 and 5.43 mg/L and r2=0.960 and 0.988)and against H.bispinosa(LC50=35.22 and 9.15 mg/L and r2=0.969 and 0.969).respectively.Conclusions:The synthesized TiO2 NPs were highly stable and had significant acaricidal activity against the larvae of R.(B.)microplus and adult of H.bispinosa.This study provides the first report of synthesized TiO2 NPs and possessed excellent anti-parasitic activity.

  16. Acaricidal activity of synthesized titanium dioxide nanoparticles using Calotropis gigantea against Rhipicephalus microplus and Haemaphysalis bispinosa

    Institute of Scientific and Technical Information of China (English)

    Sampath Marimuthu; Moorthy Iyappan; Chinnadurai Siva; Loganathan Karthik; Kokati Venkata Bhaskara Rao; Abdul Abdul Rahuman; Chidambaram Jayaseelan; Arivarasan Vishnu Kirthi; Thirunavukkarasu Santhoshkumar; Kanayairam Velayutham; Asokan Bagavan; Chinnaperumal Kamaraj; Gandhi Elango

    2013-01-01

    Objective: To assess the acaricidal activity of titanium dioxide nanoparticles (TiO2 NPs) synthesized from flower aqueous extract of Calotropis gigantea (C. gigantea) against the larvae of Rhipicephalus (Boophilus) microplus [R. (B.) microplus] and the adult of Haemaphysalis bispinosa (H. bispinosa). Methods: The lyophilized C. gigantea flower aqueous extract of 50 mg was added with 100 mL of TiO(OH)2 (10 mM) and magnetically stirred for 6 h. Synthesized TiO2 NPs were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and Energy dispersive X-ray spectroscopy (EDX). The synthesised TiO2 NPs were tested against the larvae of R. (B.) microplus and adult of H. bispinosa were exposed to filter paper impregnated method. Results:XRD confirmed the crystalline nature of the nanoparticles with the mean size of 10.52 nm. The functional groups for synthesized TiO2 NPs were 1 405.19, and 1 053.45 cm-1 for-NH2 bending, primary amines and amides and 1 053.84 and 1 078.45 cm-1 for C-O. SEM micrographs of the synthesized TiO2 NPs showed the aggregated and spherical in shape. The maximum efficacy was observed in the aqueous flower extract of C. gigantea and synthesized TiO2 NPs against R. (B.) microplus (LC50=24.63 and 5.43 mg/L and r2=0.960 and 0.988) and against H. bispinosa (LC50=35.22 and 9.15 mg/L and r2=0.969 and 0.969), respectively. Conclusions: The synthesized TiO2 NPs were highly stable and had significant acaricidal activity against the larvae of R. (B.) microplus and adult of H. bispinosa. This study provides the first report of synthesized TiO2 NPs and possessed excellent anti-parasitic activity.

  17. Evaluation of antioxidant, antibacterial and cytotoxic effects of green synthesized silver nanoparticles by Piper longum fruit

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, N. Jayachandra; Nagoor Vali, D.; Rani, M.; Rani, S. Sudha, E-mail: sadrassudha@gmail.com

    2014-01-01

    Silver nanoparticles synthesized through bio-green method has been reported to have biomedical applications to control pathogenic microbes as it is cost effective compared to commonly used physical and chemical methods. In present study, silver nanoparticles were synthesized using aqueous Piper longum fruit extract (PLFE) and confirmed by UV–visible spectroscopy. The nanoparticles were spherical in shape with an average particle size of 46 nm as determined by scanning electronic microscopy (SEM) and dynamic light scattering (DLS) particle size analyzer respectively. FT-IR spectrum revealed the capping of the phytoconstituents, probably polyphenols from P. longum fruit extract and stabilizing the nanoparticles. Further the ferric ion reducing test, confirmed that the capping agents were condensed tannins. The aqueous P. longum fruit extract (PLFE) and the green synthesized silver nanoparticles (PLAgNPs) showed powerful antioxidant properties in in vitro antioxidant assays. The results from the antimicrobial assays suggested that green synthesized silver nanoparticles (PLAgNPs) were more potent against pathogenic bacteria than the P. longum fruit extract (PLFE) alone. The nanoparticles also showed potent cytotoxic effect against MCF-7 breast cancer cell lines with an IC 50 value of 67 μg/ml/24 h by the MTT assay. These results support the advantages of using bio-green method for synthesizing silver nanoparticles with antioxidant, antimicrobial and cytotoxic activities those are simple and cost effective as well. - Highlights: • 46 nm spherical shaped P. longum fruit silver nanoparticles was prepared. • Capping and reducing bioactive plant compounds with in nanoparticles were condensed tannins. • Particles are potent antioxidant and anti microbial in biological systems. • They are cytotoxic against MCF-7 cell lines.

  18. Synergistic hydrogen desorption behavior of magnesium aluminum hydride synthesized by mechano-chemical activation method

    International Nuclear Information System (INIS)

    Highlights: ► Mg(AlH4)2 could release 3.1 wt% H2 at initial temperature as low as 100 °C. ► The synergistic and mutual catalytic effects of NaAlH4 and Mg(AlH4)2 were noticed. ► In situ synchrotron XRD confirmed the two-step dehydrogenation process of Mg(AlH4)2. - Abstract: A mechano-chemical activation synthesis (MCAS) is employed to fabricate Mg(AlH4)2 via milling the precursors, specifically NaAlH4 and MgCl2. The corresponding dehydrogenation behavior of the synthesized powders is investigated. The experimental results showed that incomplete synthesis or premature dehydrogenation may occur if the milling process was not properly controlled. The hydrogen content of each synthesized powder is determined by using a thermal gravimetric analyzer (TGA). The dehydrogenation reactions of the synthesized powders are investigated by employing ex situ X-ray diffraction (XRD), in situ synchrotron XRD and differential thermal analysis (DTA). The results showed that the incompletely synthesized powder consisted of residual NaAlH4 in the synthesized Mg(AlH4)2, which demonstrated an initial dehydrogenation temperature as low as 100 °C and accompanied with a maximum amount (3.1 wt%) of H2 released below 350 °C. The mutual catalytic effect of both NaAlH4 and Mg(AlH4)2 on lowering their initial dehydrogenation temperature is confirmed.

  19. Photocatalytic activity of galvanically synthesized nanostructure SnO2 thin films

    International Nuclear Information System (INIS)

    Graphical abstract: Nanostructured porous tin dioxide (SnO2) thin films have been synthesized by simple and cost effective galvanic technique. The synthesized porous SnO2 thin films show excellent photocatalytic activity for degrading methyl orange (MO) dye under light irradiation. The porous morphological grain growth due to annealing is likely to play an active role for this degradation. - Highlights: • SnO2 thin films have been successfully synthesized by galvanic technique. • A drastic morphological change occurs after annealing as deposited SnO2 thin films. • Morphological advantage results enhanced photodegradation of dye. - Abstract: The study demonstrates an approach to synthesize nanostructure SnO2 thin films on TCO (transparent conducting oxide) coated glass substrates by galvanic technique. Aqueous solution of hydrated stannic chloride (SnCl4⋅5H2O) in potassium nitrate (KNO3) solution was used as the working solution. The process involves no sophisticated reactor or toxic chemicals, and proceeds continuously under ambient condition; it provides an economic way of synthesizing nanostructure SnO2 semiconductor thin films. The influence of sintering temperature on crystalline structure, morphology, electrical and dielectric properties has been studied. A detail analysis of I−V, C−V and dielectrics for annealed SnO2 thin films have been carried out. The morphological advantage i.e. nanoporous flake like structure allows more efficient transport of reactant molecules to the active interfaces and results a strong photocatalytic activity for degrading methyl orange (MO) dye

  20. Photocatalytic activity of galvanically synthesized nanostructure SnO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jana, Sumanta, E-mail: sumantajana85@gmail.com [Department of Chemistry, Bengal Engineering and Science University, Botanic Garden, Howrah 711103, WB (India); Mitra, Bibhas Chandra [Department of Physics, Bengal Engineering and Science University, Botanic Garden, Howrah 711103, WB (India); Bera, Pulakesh [Department of Chemistry, Panskura Banamali College, Purba Medinipur, Panskura 721152, WB (India); Sikdar, Moushumi [Department of Chemistry, Bengal Engineering and Science University, Botanic Garden, Howrah 711103, WB (India); Mondal, Anup, E-mail: anupmondal2000@yahoo.co.in [Department of Chemistry, Bengal Engineering and Science University, Botanic Garden, Howrah 711103, WB (India)

    2014-07-25

    Graphical abstract: Nanostructured porous tin dioxide (SnO{sub 2}) thin films have been synthesized by simple and cost effective galvanic technique. The synthesized porous SnO{sub 2} thin films show excellent photocatalytic activity for degrading methyl orange (MO) dye under light irradiation. The porous morphological grain growth due to annealing is likely to play an active role for this degradation. - Highlights: • SnO{sub 2} thin films have been successfully synthesized by galvanic technique. • A drastic morphological change occurs after annealing as deposited SnO{sub 2} thin films. • Morphological advantage results enhanced photodegradation of dye. - Abstract: The study demonstrates an approach to synthesize nanostructure SnO{sub 2} thin films on TCO (transparent conducting oxide) coated glass substrates by galvanic technique. Aqueous solution of hydrated stannic chloride (SnCl{sub 4}⋅5H{sub 2}O) in potassium nitrate (KNO{sub 3}) solution was used as the working solution. The process involves no sophisticated reactor or toxic chemicals, and proceeds continuously under ambient condition; it provides an economic way of synthesizing nanostructure SnO{sub 2} semiconductor thin films. The influence of sintering temperature on crystalline structure, morphology, electrical and dielectric properties has been studied. A detail analysis of I−V, C−V and dielectrics for annealed SnO{sub 2} thin films have been carried out. The morphological advantage i.e. nanoporous flake like structure allows more efficient transport of reactant molecules to the active interfaces and results a strong photocatalytic activity for degrading methyl orange (MO) dye.

  1. For boron neutron capture therapy,synthesizing boron-polymer compounds and testing in laboratory conditions

    International Nuclear Information System (INIS)

    The aim of this project is to establish a focus point at Turkish Atomic Energy Authority (TAEA) in the field of Boron Neutron Capture Therapy which is a binary radiotherapy method for brain tumours. Moreover in the scope of the project, a new alternative of 10B-carrier compounds will be synthesized, the neutron source will be determined and the infrastructure to start the clinical trials of BNCT in our country will be established. BNCT is a binary radiotherapy method and the successful of this method is depend on the synthesized boron compounds which have the selective targeting property with tumour cells and neutron optimization. The water-soluble polymer based boron compounds having biochemical and physiological properties will be synthesized and cell culture experiment will be done. In addition, after the neutron source is set up in our country, the infrastructure studies will be started in order to start the clinical trials of BNCT. In this project, there are three different groups as boron compounds, neutron physics and medical group. Neutron physics group is starting the calculations of neutron beam parameters using in BNCT application. But, medical group has no active studies yet. Boron compounds group has been carried out two different experimental studies. In the first experimental study, functional groups have been bound to boron containing polymers to enhance the selectively targeting property and characterized by various analysis methods. Later, cell culture experiment will be done. The first study has been carried out with Hacettepe University. Up to present, completed studies are listed as: -Maleic anhydride oligomer was synthesized and then 2-aminoethyl diphenyl borate (2-AEPB) and monomethoxy poly(ethylene glycol) (PEG) was bound to this oligomer, respectively. Thus, [MAH]n-g1-2-AEPB-g2-PEG was synthesized. -2-AEPB compound were bound to poly(acrylic acid) polymer at different three mole ratio.Then, the selected Poli(Ac)-g1-2-AEPB polymer was

  2. Design of a 2.4-GHz CMOS monolithic fractional-N frequency synthesizer

    Science.gov (United States)

    Shu, Keliu

    The wireless communication technology and market have been growing rapidly since a decade ago. The high demand market is a driving need for higher integration in the wireless transceivers. The trend is to achieve low-cost, small form factor and low power consumption. With the ever-reducing feature size, it is becoming feasible to integrate the RF front-end together with the baseband in the low-cost CMOS technology. The frequency synthesizer is a key building block in the RF front-end of the transceivers. It is used as a local oscillator for frequency translation and channel selection. The design of a 2.4-GHz low-power frequency synthesizer in 0.35mum CMOS is a challenging task mainly due to the high-speed prescaler. In this dissertation, a brief review of conventional PLL and frequency synthesizers is provided. Design techniques of a 2.4-GHz monolithic SigmaDelta fractional-N frequency synthesizer are investigated. Novel techniques are proposed to tackle the speed and integration bottlenecks of high-frequency PLL. A low-power and inherently glitch-free phase-switching prescaler and an on-chip loop filter with capacitance multiplier are developed. Compared with the existing and popular dual-path topology, the proposed loop filter reduces circuit complexity and its power consumption and noise are negligible. Furthermore, a third-order three-level digital SigmaDelta modulator topology is employed to reduce the phase noise generated by the modulator. Suitable PFD and charge-pump designs are employed to reduce their nonlinearity effects and thus minimize the folding of the SigmaDelta modulator-shaped phase noise. A prototype of the fractional-N synthesizer together with some standalone building blocks is designed and fabricated in TSMC 0.35mum CMOS through MOSIS. The prototype frequency synthesizer and standalone prescaler and loop filter are characterized. The feasibility and practicality of the proposed prescaler and loop filter are experimentally verified.

  3. A simple and generic approach for synthesizing colloidal metal and metal oxide nanocrystals

    Science.gov (United States)

    Cloud, Jacqueline E.; Yoder, Tara S.; Harvey, Nathan K.; Snow, Kyle; Yang, Yongan

    2013-07-01

    A simple and generic approach--alternating voltage induced electrochemical synthesis (AVIES)--has been reported for synthesizing highly dispersed colloidal metal (Au, Pt, Sn, and Pt-Pd) and metal oxide (ZnO and TiO2) nanocrystals. The respective nanocrystals are produced when a zero-offset alternating voltage at 60 Hz is applied to a pair of identical metal wires, which are inserted in an electrolyte solution containing capping ligands. In the case of Au, the obtained nanocrystals are highly crystalline nano-icosahedra of 14 +/- 2 nm in diameter, the smallest Au icosahedra synthesized in aqueous solutions via green chemistry. Their catalytic activity has been demonstrated through facilitating the reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride. This AVIES approach is an environmentally benign process and can be adopted by any research lab.

  4. Characterization and catalytic activity of gold nanoparticles synthesized using ayurvedic arishtams

    Science.gov (United States)

    Aswathy Aromal, S.; Dinesh Babu, K. V.; Philip, Daizy

    2012-10-01

    The development of new synthesis methods for monodispersed nanocrystals using cheap and nontoxic chemicals, environmentally benign solvents and renewable materials remains a challenge to the scientific community. The present work reports a new green method for the synthesis of gold nanoparticles. Four different ayurvedic arishtams are used for the reduction of Au3+ to Au nanoparticles. This method is simple, efficient, economic and nontoxic. Gold nanoparticles having different sizes in the range from 15 to 23 nm could be obtained. The nanoparticles have been characterized by UV-Visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR analysis. The high crystallinity of nanoparticles is evident from bright circular spots in the SAED pattern and peaks in the XRD pattern. The synthesized gold nanoparticles show good catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol by excess NaBH4. The synthesized nanoparticles are found to exhibit size dependent catalytic property, the smaller nanoparticles showing faster activity.

  5. Syntheses of Sulfo-Glycodendrimers Using Click Chemistry and Their Biological Evaluation

    Directory of Open Access Journals (Sweden)

    Tomohiro Fukuda

    2012-10-01

    Full Text Available A series of novel glycol-clusters containing sulfonated N-acetyl-D-glucosamine (GlcNAc have been synthesized using click chemistry. Three dendrimers with aromatic dendrons were synthesized using chlorination, azidation and click chemistries. The resulting dendrimers were modified with azide-terminated sulfonated GlcNAc using click chemistry. The sulfonated dendrimers showed affinity for proteins, including the lectin wheat germ agglutinin and amyloid beta peptide (1-42. The dendrimers of G1 and G2 in particular showed the largest affinity for the proteins. The addition of the sulfonated GlcNAc dendrimers of G1 and G2 exhibited an inhibition effect on the aggregation of the amyloid beta peptide, reduced the b-sheet conformation, and led to a reduction in the level of nanofiber formation.

  6. A Study On Dispersion Stability Of Nickel Nanoparticles Synthesized By Wire Explosion In Liquid Media

    Directory of Open Access Journals (Sweden)

    Kim C.K.

    2015-06-01

    Full Text Available In this study, nickel nanoparticles were synthesized in ethanol using portable pulsed wire evaporation, which is a one-step physical method. From transmission electron microscopy images, it was found that the Ni nanoparticles exhibited a spherical shape with an average diameter of 7.3 nm. To prevent aggregation of the nickel nanoparticles, a polymer surfactant was added into the ethanol before the synthesis of nickel nanoparticles, and adsorbed on the freshly synthesized nickel nanoparticles during the wire explosion. The dispersion stability of the prepared nickel nanofluids was investigated by zeta-potential analyzer and Turbiscan optical analyzer. As a result, the optimum concentration of polymer surfactant to be added was suggested for the maximized dispersion stability of the nickel nanofluids.

  7. Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

    Science.gov (United States)

    Nam, Chang-Yong; Stein, Aaron; Kisslinger, Kim; Black, Charles T.

    2015-11-01

    We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ˜1019 cm-3 carrier density, and ˜0.1 cm2 V-1 s-1 electron mobility, reflecting highly nanocrystalline internal structure. The results demonstrate the potential application of infiltration synthesis in fabricating metal oxide electronic devices.

  8. Size-dependent antimicrobial properties of sugar-encapsulated gold nanoparticles synthesized by a green method

    Science.gov (United States)

    Badwaik, Vivek D.; Vangala, Lakshmisri M.; Pender, Dillon S.; Willis, Chad B.; Aguilar, Zoraida P.; Gonzalez, Matthew S.; Paripelly, Rammohan; Dakshinamurthy, Rajalingam

    2012-11-01

    The antimicrobial properties of dextrose-encapsulated gold nanoparticles (dGNPs) with average diameters of 25, 60, and 120 nm (± 5) and synthesized by green chemistry principles were investigated against both Gram-negative and Gram-positive bacteria. Studies were performed involving the effect of dGNPs on the growth, morphology, and ultrastructural properties of bacteria. dGNPs were found to have significant dose-dependent antibacterial activity which was also proportional to their size. Experiments revealed the dGNPs to be bacteriostatic as well as bactericidal. The dGNPs exhibited their bactericidal action by disrupting the bacterial cell membrane which leads to the leakage of cytoplasmic content. The overall outcome of this study suggests that green-synthesized dGNPs hold promise as a potent antibacterial agent against a wide range of disease-causing bacteria by preventing and controlling possible infections or diseases.

  9. Design Considerations for Autocalibrations of Wide-Band ΔΣ Fractional-N PLL Synthesizers

    Directory of Open Access Journals (Sweden)

    Jaewook Shin

    2011-01-01

    Full Text Available Autocalibration of VCO frequency and loop gain is an essential process in PLL frequency synthesizers. In a wide tuning-range fractional-N PLL frequency synthesizer, high-speed and high-precision automatic calibration is especially important for shortening the lock time and improving the phase noise. This paper reviews the design issues of the PLL auto-calibration and discusses on the limitations of the previous techniques. A very simple and efficient auto-calibration method based on a high-speed frequency-to-digital converter (FDC is proposed and verified through simulations. The proposed method is highly suited for a very wide-band ΔΣ fractional-N PLL.

  10. Spectroscopic and biological studies on newly synthesized nickel(II) complexes of semicarbazones and thiosemicarbazones

    Science.gov (United States)

    Chandra, Sulekh; Gupta, Lokesh Kumar

    2005-12-01

    Nickel(II) complexes, having the general composition Ni(L) 2X 2, have been synthesized [where L: isopropyl methyl ketone semicarbazone (LLA), isopropyl methyl ketone thiosemicarbazone (LLB), 4-aminoacetophenone semicarbazone (LLC) and 4-aminoacetophenone thiosemicarbazone (LLD) and X = Cl -, 1/2SO 42-]. All the Ni(II) complexes reported here have been characterized by elemental analyses, magnetic moments, IR, electronic and mass spectral studies. All the complexes were found to have magnetic moments corresponding to two unpaired electrons. The possible geometries of the complexes were assigned on the basis of electronic and infrared spectral studies. Newly synthesized ligand and its nickel(II) complexes have been screened against different bacterial and fungal growth.

  11. Fabrication of porous Al2O3-based ceramics using combustion synthesized powders

    Directory of Open Access Journals (Sweden)

    Jiahai Bai

    2012-03-01

    Full Text Available Porous Al2O3-based ceramics were fabricated from powders synthesized via a solution combustion process using starch and urea as fuels. Effects of the relative fuel-to-oxidant ratio (φe = 1.4, 1.6, 1.8 and 2.0, respectively on open porosity, pore size distribution and flexural strength of the as-prepared porous Al2O3-based ceramics were investigated. Experimental results revealed that the densification ability of the as-synthesized powders increased significantly as φe increased, and open porosity, pore size distribution and flexural strength of the porous ceramics exhibited remarkable dependence on the densification ability of the powders instead of the weight fraction of the charred organic residuals in the powders. SEM micrographs disclosed that the porous ceramics from the precursors with φe = 1.8 or 2.0 exhibited significantly homogenous microstructures including pore size and pore distribution.

  12. Mycosynthesis: antibacterial, antioxidant and antiproliferative activities of silver nanoparticles synthesized from Inonotus obliquus (Chaga mushroom) extract.

    Science.gov (United States)

    Nagajyothi, P C; Sreekanth, T V M; Lee, Jae-il; Lee, Kap Duk

    2014-01-01

    In the present study, silver nanoparticles (AgNPs) were rapidly synthesized from silver nitrate solution at room temperature using Inonotus obliquus extract. The mycogenic synthesized AgNPs were characterized by UV-Visible absorption spectroscopy, Fourier transform infrared (FTIR), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). SEM revealed mostly spherical nanoparticles ranging from 14.7 to 35.2nm in size. All AgNPs concentrations showed good ABT radical scavenging activity. Further, AgNPs showed effective antibacterial activity against both gram negative and gram positive bacteria and antiproliferative activity toward A549 human lung cancer (CCL-185) and MCF-7 human breast cancer (HTB-22) cell lines. The samples demonstrated considerably high antibacterial, and antiproliferative activities against bacterial strains and cell lines. PMID:24380885

  13. Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Chang-Yong, E-mail: cynam@bnl.gov; Stein, Aaron; Kisslinger, Kim; Black, Charles T. [Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973 (United States)

    2015-11-16

    We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ∼10{sup 19 }cm{sup −3} carrier density, and ∼0.1 cm{sup 2} V{sup −1} s{sup −1} electron mobility, reflecting highly nanocrystalline internal structure. The results demonstrate the potential application of infiltration synthesis in fabricating metal oxide electronic devices.

  14. Study of various Sb2S3 nanostructures synthesized by simple solvothermal and hydrothermal methods

    International Nuclear Information System (INIS)

    Controlling the size and morphology of the antimony sulfide nanostructures is important for photocatalytic and photovoltaic applications. Herein, we report a systematic approach to synthesize various nanostructures of antimony sulfide. Based on simple solvothermal and hydrothermal routes antimony sulfide nanorods have been synthesized at different temperatures. The size of the nanorods and the morphology of the constituent nano-units, in the form of nanorods, dumbbell and sphere have been controlled by adjusting the temperature. The changes have been confirmed by scanning electron microscope and transmission electron microscope analysis. - Highlights: • We prepared dumbbell structured Sb2Sb3 by simple solvothermal and hydrothermal method. • Investigated the importance of bath temperature on the formation of various structures. • Growth mechanism of dumbbell like structured Sb2S3 nanorods was estimated

  15. Synthesize of barium ferrite nanowire array by self-fabricated porous silicon template

    Science.gov (United States)

    Zheng, Hui; Han, Mangui; Deng, Jiangxia; Zheng, Liang; Wu, Jun; Deng, Longjiang; Qin, Huibin

    2014-08-01

    In this work, we synthesize barium ferrite (BaFe12O19) nanowire array in porous silicon template. The porous silicon templates are prepared via gold-assisted chemical etching method. The gold (Au) nanoparticles with mean diameter of 30 nm and distance of 100 nm were ordered on the surface of Si substrate through the Polystyrene (510000)-block-poly (2-vinylpyridine) (31000) (PS510000-b-P2VP31000) diblock copolymer. Porous silicon templates with mean diameter of 500 nm and distance between the pores of 500 nm were fabricated by two etching steps. BaFe12O19 nanowires with mean diameter of 200 nm were synthesized into a porous silicon template by a sol-gel method. Magnetic hysteresis loops show an isotropic feature of the BaFe12O19 nanowires array. The coercivity (Hc) and squareness ratio (Mr/Ms) of nanowire arrays are 2560 Oe and 0.6, respectively.

  16. Electrical and structural properties of ZnO synthesized via infiltration of lithographically defined polymer templates

    International Nuclear Information System (INIS)

    We investigate the electrical and structural properties of infiltration-synthesized ZnO. In-plane ZnO nanowire arrays with prescribed positional registrations are generated by infiltrating diethlyzinc and water vapor into lithographically defined SU-8 polymer templates and removing organic matrix by oxygen plasma ashing. Transmission electron microscopy reveals that homogeneously amorphous as-infiltrated polymer templates transform into highly nanocrystalline ZnO upon removal of organic matrix. Field-effect transistor device measurements show that the synthesized ZnO after thermal annealing displays a typical n-type behavior, ∼1019 cm−3 carrier density, and ∼0.1 cm2 V−1 s−1 electron mobility, reflecting highly nanocrystalline internal structure. The results demonstrate the potential application of infiltration synthesis in fabricating metal oxide electronic devices

  17. One-dimensional polyaniline nanostructures synthesized by interfacial polymerization in a solids-stabilized emulsion

    Science.gov (United States)

    He, Yongjun

    2006-01-01

    One-dimensional polyaniline nanostructures were synthesized by interfacial polymerization in a solids-stabilized oil/water emulsion for the first time. The products were characterized with TEM, FTIR and UV-vis. FTIR analyses proved the polyaniline synthesized were of emeraldine salt form; the results of TEM showed that when MgCO 3 and CaCO 3 particles were used as emulsifiers, polyaniline nanofibers with an average diameter of 33 nm and nanotubes with an average outer diameter of 28 nm were obtained, respectively. Comparing to ordinary interfacial polymerization approach, our new route needed much less amount of oil phase and shorter polymerization time. A possible mechanism for the formation of one-dimensional polyaniline nanostructures was suggested.

  18. Interferometric diameter determination of a silicon sphere using a traceable single laser frequency synthesizer

    International Nuclear Information System (INIS)

    To determine the absolute diameter of a silicon sphere for the Avogadro constant project, we present a phase-shifting interferometer based on a flat etalon and a traceable single laser frequency synthesizer. By using an optical frequency comb to calibrate a frequency-tunable diode laser, the single laser frequency synthesizer can produce an arbitrary laser frequency with a relative uncertainty of 9.2 × 10−12 in the range of 4 THz. According to the laser frequency tuning system, the Carré algorithm with arbitrary but equal phase steps is employed to calculate the fractional interference phases. The absolute diameter is obtained by measuring the fractional and integral parts based on the principles of phase-shifting interferometry and frequency-sweeping interferometry, respectively. The uncertainty of a single diameter measurement in air is estimated to be 5 nm, whose uncertainty sources from the laser frequency and the phase-shifting algorithm are negligible. (paper)

  19. Fabrication of fluorescent composite with ultrafast aqueous synthesized high luminescent CdTe quantum dots

    International Nuclear Information System (INIS)

    Without precursor preparation, inert gas protection and enormous amount of additives and reductants, CdTe quantum dots (QDs) can be rapidly synthesized with high quality. A 600 nm photoluminescence peak wavelength could be obtained within 1 hour's refluxing through minimal addition of 1,2-diaminoethane (DAE). The theoretical design for the experiments are illustrated and further proved by the characterization results with different concentrations and reagents. On the other hand, generation of CdTe QDs was found even under room temperature by applying droplet quantity of DAE. This indicates that QDs can be synthesized with simply a bottle and no enormous additives required. The QDs were mixed into the epoxy matrix through solution casting method with cetyltrimethylammonium (CTA) capping for phase transfer. The acquired epoxy based nanocomposite exhibits good transparency, compatibility and fluorescence

  20. Syntheses of Fe–TiC nanocomposite from ilmenite concentrate via microwave heating

    Indian Academy of Sciences (India)

    Mansour Razavi; Mohammad Reza Rahimipour; Tooraj Ebadzadeh; Seyed Salman Razavi Tousi

    2009-04-01

    In this paper, the possibility of production of Fe–TiC nanocomposite as a useful ceramic, from ilmenite concentrate, aluminum powder and carbon black has been investigated. Different amounts of FeTiO3, carbon black and Al powder were activated by a high-energy ball mill. Then the mixtures were synthesized by microwave heating at various times. The results of XRD investigation indicated that TiC has been synthesized within 5–10 min treatment microwave time. Moreover, it was found that by increasing the aluminum content, the Fe2O3 phase was replaced by SiC and Al2O3. In addition, from the broadening of the diffraction lines in the XRD patterns analysis, it was concluded that the TiC crystallites are nano-sized. Also, it was found that the existence of Al lead to increased grain size and decrease of the strain in the process.