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Sample records for acetobacter xylinum synthesized

  1. Characterization of genes in the cellulose-synthesizing operon (acs operon) of Acetobacter xylinum: implications for cellulose crystallization.

    PubMed Central

    Saxena, I M; Kudlicka, K; Okuda, K; Brown, R M

    1994-01-01

    The synthesis of an extracellular ribbon of cellulose in the bacterium Acetobacter xylinum takes place from linearly arranged, membrane-localized, cellulose-synthesizing and extrusion complexes that direct the coupled steps of polymerization and crystallization. To identify the different components involved in this process, we isolated an Acetobacter cellulose-synthesizing (acs) operon from this bacterium. Analysis of DNA sequence shows the presence of three genes in the acs operon, in which the first gene (acsAB) codes for a polypeptide with a molecular mass of 168 kDa, which was identified as the cellulose synthase. A single base change in the previously reported DNA sequence of this gene, resulting in a frameshift and synthesis of a larger protein, is described in the present paper, along with the sequences of the other two genes (acsC and acsD). The requirement of the acs operon genes for cellulose production was determined using site-determined TnphoA/Kanr GenBlock insertion mutants. Mutant analysis showed that while the acsAB and acsC genes were essential for cellulose production in vivo, the acsD mutant produced reduced amounts of two cellulose allomorphs (cellulose I and cellulose II), suggesting that the acsD gene is involved in cellulose crystallization. The role of the acs operon genes in determining the linear array of intramembranous particles, which are believed to be sites of cellulose synthesis, was investigated for the different mutants; however, this arrangement was observed only in cells that actively produced cellulose microfibrils, suggesting that it may be influenced by the crystallization of the nascent glucan chains. Images PMID:8083166

  2. SYNTHESIS OF CELLULOSE BY ACETOBACTER XYLINUM VI.

    PubMed Central

    Gromet-Elhanan, Zippora; Hestrin, Shlomo

    1963-01-01

    Gromet-Elhanan, Zippora (The Hebrew University, Jerusalem, Israel) and Shlomo Hestrin. Synthesis of cellulose by Acetobacter xylinum. VI. Growth on citric acid-cycle intermediates. J. Bacteriol. 85:284–292. 1963.—Acetobacter xylinum could be made to grow on ethanol, acetate, succinate, or l-malate. The growth was accompanied by formation of opaque leathery pellicles on the surface of the growth medium. These pellicles were identified as cellulose on the basis of their chemical properties, solubility behavior, and infrared absorption spectra. Washed-cell suspensions prepared from cultures grown on ethanol or the organic acids, in contrast to washed sugar-grown cells, were able to transform citric-cycle intermediates into cellulose. The variations in the substrate spectrum of cellulose synthesis between sugar-grown cells and organic acids-grown cells were found to be correlated with differences in the oxidative capacity of the cells. The significance of the findings that A. xylinum could be made to grow on ethanol on complex as well as synthetic media is discussed from the viewpoint of the whole pattern of Acetobacter classification. PMID:13950665

  3. Network Model of Acetobacter Xylinum Cellulose Intercalated by Drug Nanoparticles

    NASA Astrophysics Data System (ADS)

    Klechkovskaya, Vera V.; Volkov, Vladimir V.; Shtykova, Eleonora V.; Arkharova, Natalia A.; Baklagina, Yulia G.; Khripunov, Albert K.; Smyslov, Ruslan Yu.; Borovikova, Ludmila N.; Tkachenko, Albina A.

    It was shown that Acetobacter xylinum cellulose gel-films can sorb silver and selenium nanoparticles stabilized by N-poly(vinyl-2-pirrolidone). The structure of original cellulose matrix, isolated nanoparticles and cellulose with sorbed nanoparticles was characterized by electron diffraction, electron microscopy, small- and wide-angle x-ray scattering methods, and atomic force microscopy. It was found that in static culture Acetobacter xylinum bacterium (strain VKM B-880) may synthesize high-molecular cellulose with narrow molecular weight distribution and a considerable number of carbon sources. The structures of cellulose microfibrilles and ribbons correspond mainly to polymorphous Iβ modification. We concluded from structural studies that textured cellulose films were formed. The sorption conditions of poly(vinylpyrrolidone)-Se° and poly(vinylpyrrolidone)-Ag° nanoparticles were optimized to obtain a cellulose template that can be used in medical practice.

  4. Genetic organization of the cellulose synthase operon in Acetobacter xylinum.

    PubMed Central

    Wong, H C; Fear, A L; Calhoon, R D; Eichinger, G H; Mayer, R; Amikam, D; Benziman, M; Gelfand, D H; Meade, J H; Emerick, A W

    1990-01-01

    An operon encoding four proteins required for bacterial cellulose biosynthesis (bcs) in Acetobacter xylinum was isolated via genetic complementation with strains lacking cellulose synthase activity. Nucleotide sequence analysis indicated that the cellulose synthase operon is 9217 base pairs long and consists of four genes. The four genes--bcsA, bcsB, bcsC, and bcsD--appear to be translationally coupled and transcribed as a polycistronic mRNA with an initiation site 97 bases upstream of the coding region of the first gene (bcsA) in the operon. Results from genetic complementation tests and gene disruption analyses demonstrate that all four genes in the operon are required for maximal bacterial cellulose synthesis in A. xylinum. The calculated molecular masses of the proteins encoded by bcsA, bcsB, bcsC, and bcsD are 84.4, 85.3, 141.0, and 17.3 kDa, respectively. The second gene in the operon (bcsB) encodes the catalytic subunit of cellulose synthase. The functions of the bcsA, bcsC, and bcsD gene products are unknown. Bacterial strains mutated in the bcsA locus were found to be deficient in cellulose synthesis due to the lack of cellulose synthase and diguanylate cyclase activities. Mutants in the bcsC and bcsD genes were impaired in cellulose production in vivo, even though they had the capacity to make all the necessary metabolic precursors and cyclic diguanylic acid, the activator of cellulose synthase, and exhibit cellulose synthase activity in vitro. When the entire operon was present on a multicopy plasmid in the bacterial cell, both cellulose synthase activity and cellulose biosynthesis increased. When the promoter of the cellulose synthase operon was replaced on the chromosome by E. coli tac or lac promoters, cellulose production was reduced in parallel with decreased cellulose synthase activity. These observations suggest that the expression of the bcs operon is rate-limiting for cellulose synthesis in A. xylinum. Images PMID:2146681

  5. Bacterial Cellulose Production by Acetobacter xylinum Strains from Agricultural Waste Products

    NASA Astrophysics Data System (ADS)

    Kongruang, Sasithorn

    Bacterial cellulose is a biopolysaccharide produced from the bacteria, Acetobacter xylinum. Static batch fermentations for bacterial cellulose production were studied in coconut and pineapple juices under 30 °C in 5-1 fermenters by using three Acetobacter strains: A. xylinum TISTR 998, A. xylinum TISTR 975, and A. xylinum TISTR 893. Experiments were carried out to compare bacterial cellulose yields along with growth kinetic analysis. Results showed that A. xylinum TISTR 998 produced a bacterial cellulose yield of 553.33 g/l, while A. xylinum TISTR 893 produced 453.33 g/l and A. xylinum TISTR 975 produced 243.33 g/l. In pineapple juice, the yields for A. xylinum TISTR 893, 975, and 998 were 576.66, 546.66, and 520 g/l, respectively. The strain TISTR 998 showed the highest productivity when using coconut juice. Morphological properties of cellulose pellicles, in terms of texture and color, were also measured, and the textures were not significantly different among treatments.

  6. Effect of tungsten concentration on growth of acetobacter xylinum as a promising agent for eco-friendly recycling system

    NASA Astrophysics Data System (ADS)

    Nandiyanto, A. B. D.; Halimatul, H. S.; Rosyid, N. H.; Effendi, D. B.

    2016-04-01

    Effect of tungsten (W) concentration on Acetobacter xylinum growth was studied. In the experimental procedure, concentration of W in the bacterial growth medium containing pineapple peels waste was varied from 0.5 to 50 ppm. To confirm the influence of W, the bacterial incubation process was carried out for 72 hours. Spectrophotometer analysis showed that the growth rate of Acetobacter xylinum decreased with increasing concentration of W. The result from fourier transform infra red analysis showed a slightly change on the absorption peak intensities and informing the interaction of W ion and bacteria cell. The result confirmed that Acetobacter xylinum was able to uptake W concentration up to 15 ppm, indicating that Acetobacter xylinum might act as a promising agent for eco-friendly recycling system.

  7. Cloning and sequencing of the beta-glucosidase gene from Acetobacter xylinum ATCC 23769.

    PubMed

    Tajima, K; Nakajima, K; Yamashita, H; Shiba, T; Munekata, M; Takai, M

    2001-12-31

    The beta-glucosidase gene (bglxA) was cloned from the genomic DNA of Acetobacter xylinum ATCC 23769 and its nucleotide sequence (2200 bp) was determined. This bglxA gene was present downstream of the cellulose synthase operon and coded for a polypeptide of molecular mass 79 kDa. The overexpression of the beta-glucosidase in A. xylinum caused a tenfold increase in activity compared to the wild-type strain. In addition, the action pattern of the enzyme was identified as G3ase activity. The deduced amino acid sequence of the bglxA gene showed 72.3%, 49.6%, and 45.1% identity with the beta-glucosidases from A. xylinum subsp. sucrofermentans, Cellvibrio gilvus, and Mycobacterium tuberculosis, respectively. Based on amino acid sequence similarities, the beta-glucosidase (BglxA) was assigned to family 3 of the glycosyl hydrolases.

  8. An Acetobacter xylinum insertion sequence element associated with inactivation of cellulose production.

    PubMed Central

    Coucheron, D H

    1991-01-01

    An insertion sequence (IS) element, IS1031, caused insertions associated with spontaneous cellulose deficient (Cel-) mutants of Acetobacter xylinum ATCC 23769. The element was discovered during hybridization analysis of DNAs from Cel- mutants of A. xylinum ATCC 23769 with pAXC145, an indigenous plasmid from a Cel- mutant of A. xylinum NRCC 17005. An IS element, IS1031B, apparently identical to IS1031, was identified on pAXC145. IS1031 is about 950 bp. DNA sequencing showed that the two elements had identical termini with inverted repeats of 24 bp containing two mismatches and that they generated 3-bp target sequence duplications. The A. xylinum ATCC 23769 wild type carries seven copies of IS1031. Southern hybridization showed that 8 of 17 independently isolated spontaneous Cel- mutants of ATCC 23769 contained insertions of an element homologous to IS1031. Most insertions were in unique sites, indicating low insertion specificity. Significantly, two insertions were 0.5 kb upstream of a recently identified cellulose synthase gene. Attempts to isolate spontaneous cellulose-producing revertants of these two Cel- insertion mutants by selection in static cultures were unsuccessful. Instead, pseudorevertants that made waxlike films in the liquid-air interface were obtained. The two pseudorevertants carried new insertions of an IS1031-like element in nonidentical sites of the genome without excision of the previous insertions. Taken together, these results suggest that indigenous IS elements contribute to genetic instability in A. xylinum. The elements might also be useful as genetic tools in this organism and related species. Images PMID:1653216

  9. Utilization of the buffering capacity of corn steep liquor in bacterial cellulose production by Acetobacter xylinum.

    PubMed

    Noro, N; Sugano, Y; Shoda, M

    2004-04-01

    Acetobacter xylinum BPR2001 produces water-insoluble bacterial cellulose (BC). Using a pH sensor for the accurate control of pH, which is one of the most critical factors for efficient BC production, is difficult especially in a baffled shake-flask and an airlift reactor. The buffering capacity of corn steep liquor (CSL) was estimated by measuring beta (buffering capacity) values in advance and was used to maintain the pH within the optimal range during the production of BC. When CSL was added to either a shake-flask, a stirred-tank reactor or an airlift reactor, BC production was almost the same as that in cultivations where pH was controlled manually or by a pH sensor.

  10. Minerals consumption by Acetobacter xylinum on cultivation medium on coconut water

    PubMed Central

    Almeida, Denise Milleo; Prestes, Rosilene Aparecida; da Fonseca, Adriel Ferreira; Woiciechowski, Adenise L.; Wosiacki, Gilvan

    2013-01-01

    The objective of this work is to verifying the consume of the minerals K, Na, Fe, Mg, P, S-SO4−2, B, N Total Kjedahl (NTK), NO3−-N, and NH4+-N in the production of bacterial cellulose by Acetobacter xylinum, according to the medium and the manner of cultivation. The fermentative process was in ripe and green coconut water. K and Na were determined by flame emission photometry, Mg and Fe by atomic absorption spectrophotometry, P by molecular absorption spectrophotometry, S-SO4−2 by barium sulphate turbidimetry, B by Azomethin-H method, NTK by Kjeldahl method, N-NO3− and N-NH4+ by vapor distillation with magnesium oxide and Devarda’s alloy, respectively. In Fermentation of ripe coconut water there were higher consumption of K (69%), Fe (84,3%), P (97,4%), S-SO2−2 (64,9%), B (56,1%), N-NO3− (94,7%) and N-NH4+ (95,2%), whereas coconut water of green fruit the most consumed ions were Na (94,5%), Mg (67,7%) and NTK (56,6%). The cultivation under agitation showed higher mineral consumption. The higher bacterial cellulose production, 6 g.L−1, was verified in the coconut water fermentative in ripe fruit, added KH2PO4, FeSO4 and NaH2PO4 kept under agitation. PMID:24159306

  11. Minerals consumption by Acetobacter xylinum on cultivation medium on coconut water.

    PubMed

    Almeida, Denise Milleo; Prestes, Rosilene Aparecida; da Fonseca, Adriel Ferreira; Woiciechowski, Adenise L; Wosiacki, Gilvan

    2013-01-01

    The objective of this work is to verifying the consume of the minerals K, Na, Fe, Mg, P, S-SO4 (-2), B, N Total Kjedahl (NTK), NO3 (-)-N, and NH4 (+)-N in the production of bacterial cellulose by Acetobacter xylinum, according to the medium and the manner of cultivation. The fermentative process was in ripe and green coconut water. K and Na were determined by flame emission photometry, Mg and Fe by atomic absorption spectrophotometry, P by molecular absorption spectrophotometry, S-SO4 (-2) by barium sulphate turbidimetry, B by Azomethin-H method, NTK by Kjeldahl method, N-NO3 (-) and N-NH4 (+) by vapor distillation with magnesium oxide and Devarda's alloy, respectively. In Fermentation of ripe coconut water there were higher consumption of K (69%), Fe (84,3%), P (97,4%), S-SO2 (-2) (64,9%), B (56,1%), N-NO3 (-) (94,7%) and N-NH4 (+) (95,2%), whereas coconut water of green fruit the most consumed ions were Na (94,5%), Mg (67,7%) and NTK (56,6%). The cultivation under agitation showed higher mineral consumption. The higher bacterial cellulose production, 6 g.L(-1), was verified in the coconut water fermentative in ripe fruit, added KH2PO4, FeSO4 and NaH2PO4 kept under agitation.

  12. Formation and characterization of spherelike bacterial cellulose particles produced by Acetobacter xylinum JCM 9730 strain.

    PubMed

    Hu, Yang; Catchmark, Jeffrey M

    2010-07-12

    Spherelike cellulose formation as a function of agitated culture rotational speeds and flask sizes for two different cellulose producing Acetobacter xylinum strains, JCM 9730 (ATCC 700178) and NCIMB (ATCC 23769), has been studied in this work. Results showed that the JCM 9730 strain could form spherelike cellulose particles in the agitated culture with a rotational speed above 100 rpm. The NCIMB strain, however, formed no spherelike cellulose particles under any culture condition examined. For the JCM 9730 strain, approximately 10 mm diameter spheres were produced at a rotational speed of 150 rpm in 100 mL of culture solution in a 150 mL Erlenmeyer flask, while 0.5-1 mm diameter particles were produced in 100 mL of agitated culture with a rotational speed of 200 rpm in a 250 mL Erlenmeyer flask. Data from the measurement of biomass concentration and bacterial cellulose concentration revealed that the JCM 9730 strain exhibited higher cellulose yield (up to 6.8 times) as compared to the NCIMB strain. Scanning electron microscopy analysis of lyophilized spherelike cellulose particles indicated that culture rotational speed had an impact on the internal structure of the spherelike particles. Smaller spherelike particles produced at 150 rpm were hollow and the cellulose shell exhibited a layered structure. Larger particles produced at 125 rpm were solid where the cellulose in the central region did not exhibit a layered structure, but the outer layer was similar in structure to the particles produced at 150 rpm.

  13. Green synthesis of silver and gold nanoparticles employing levan, a biopolymer from Acetobacter xylinum NCIM 2526, as a reducing agent and capping agent.

    PubMed

    Ahmed, Khan Behlol Ayaz; Kalla, Divya; Uppuluri, Kiran Babu; Anbazhagan, Veerappan

    2014-11-04

    With a vision of finding greener materials to synthesize nanoparticles, we report the production and isolation of levan, a polysaccharide with repeating units of fructose, from Acetobacter xylinum NCIM2526. The isolated levan were characterized using potassium ferricyanide reducing power assay, Fourier transform infra-red (FTIR) spectroscopy and (1)H nuclear magnetic resonance spectroscopy ((1)H NMR). To exploit levan in nanotechnology, we present a simple and greener method to synthesize silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using biopolymer, levan as both reducing and stabilizing agents. The morphology and stability of the AgNPs and AuNPs were examined by transmission electron microscopy (TEM) and UV-vis absorption (UV-vis) spectroscopy. The possible capping mechanism of the nanoparticles was postulated using FTIR studies. As synthesized biogenic nanoparticles showed excellent catalytic activity as evidenced from sodium borohydride mediated reduction of 4-nitro phenol and methylene blue.

  14. Isolation and nucleotide sequence of the GDP-mannose:cellobiosyl-diphosphopolyprenol alpha-mannosyltransferase gene from Acetobacter xylinum.

    PubMed Central

    Petroni, E A; Ielpi, L

    1996-01-01

    A genetic locus from Acetobacter xylinum involved in acetan polysaccharide synthesis has been characterized. The chromosomal region was identified by screening a genomic library of A. xylinum in a Xanthomonas campestris mutant defective in xanthan polysaccharide synthesis. The A. xylinum cosmid clone can functionally complement a xanthan-negative mutant. The polymer produced by the recombinant strain was found to be indistinguishable from xanthan. Insertion mutagenesis and subcloning of the cosmid clone combined with complementation studies allowed the identification of a 2.3-kb fragment of A. xylinum chromosomal DNA. The nucleotide sequence of this fragment was analyzed and found to contain an open reading frame (aceA) of 1,182 bp encoding a protein of 43.2 kDa. Results from biochemical and genetic analyses strongly suggest that the aceA gene encodes the GDP-mannose:cellobiosyl-diphosphopolyprenol alpha-mannosyltransferase enzyme, which is responsible for the transfer of an alpha-mannosyl residue from GDP-Man to cellobiosyl-diphosphopolyprenol. A search for similarities with other known mannosyltransferases revealed that all bacterial alpha-mannosyltransferases have a short COOH-terminal amino acid sequence in common. PMID:8759843

  15. Effect of addition of sodium alginate on bacterial cellulose production by Acetobacter xylinum.

    PubMed

    Zhou, L L; Sun, D P; Hu, L Y; Li, Y W; Yang, J Z

    2007-07-01

    Bacterial cellulose (BC) production by Acetobacter xylinum NUST4.1 was carried out in the shake flask and in a stirred-tank reactor by means of adding sodium alginate (NaAlg) into the medium. When 0.04% (w/v) NaAlg was added in the shake flask, BC production reached 6.0 g/l and the terminal yield of the cellulose was 27% of the total sugar initially added, compared with 3.7 g/l and 24% in the control, respectively. The variation between replicates in all determinations was less than 5%. During the cultivation in the stirred-tank reactor, the addition of NaAlg changed the morphology of cellulose from the irregular clumps and fibrous masses entangled in the internals to discrete masses dispersing into the broth, which indicates that NaAlg hinders formation of large clumps of BC, and enhances cellulose yield. Because the structure of cellulose is changed depending on the culture condition such as additives, structural characteristics of BC produced in the NaAlg-free and NaAlg medium are compared using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD). SEM photographs show some differences in reticulated structures and ribbon width and FT-IR spectra indicate that there is the hydrogen bonding interaction between BC and NaAlg, then X-ray diffraction (XRD) analysis reveals that BC produced with NaAlg-added has a lower crystallinity and a smaller crystalline size. The results show that enhanced yields and modification of cellulose structure occur in the presence of NaAlg.

  16. Characterization of chemically treated bacterial (Acetobacter xylinum) biopolymer: some thermo-mechanical properties.

    PubMed

    George, Johnsy; Ramana, Karna Venkata; Sabapathy, Shanmugham Nadana; Jagannath, Jambur Hiriyannaiah; Bawa, Amarinder Singh

    2005-12-15

    Bacterial cellulose prepared from pellicles of Acetobacter xylinum (Gluconacetobacter xylinus) is a unique biopolymer in terms of its molecular structure, mechanical strength and chemical stability. The biochemical analysis revealed that various alkali treatment methods were effective in removing proteins and nucleic acids from native membrane resulting in pure cellulose membrane. The effect of various treatment regimens on thermo-mechanical properties of the material was investigated. The cellulose in the form of purified cellulose membranes was characterized by differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA). The glass transition temperature (T(g)) of the native cellulose (untreated, compressed and dried pellicle) was found to be 13.94 degrees C, in contrast, the chemically treated cellulose membranes has higher T(g) values, ranging from 41.41 degrees C to 48.82 degrees C. Investigations on isothermal crystallization were carried out to study the bulk crystallization kinetics. Thermal decomposition pattern of the native as well as alkali treated cellulose was determined by obtaining thermo-gravimetric curves. At higher temperatures (>300 degrees C), the biopolymer was found to degrade. Nevertheless, the alkaline treated cellulose membrane was more stable (between 343.27 degrees C and 370.05 degrees C) in comparison to the native cellulose (298.07 degrees C). Further, the percentage weight loss in case of native cellulose was found to be 26.57%, in comparison to 6.45% for the treated material, at 300 degrees C. The DMTA revealed complex dynamic modulus of the material, at different temperatures and fixed shear stress, applied at a frequency of 5 Hz. The study delineated the effect of alkali treatment regimens, on the thermo-mechanical properties of bacterial cellulose for its application over a wide range of temperatures.

  17. Interaction of Se{sup 0} nanoparticles stabilized by poly(vinylpyrrolidone) with gel films of cellulose Acetobacter xylinum

    SciTech Connect

    Baklagina, Yu. G.; Khripunov, A. K.; Tkachenko, A. A.; Suvorova, E. I.; Klechkovskaya, V. V. Borovikova, L. N.; Smyslov, R. Yu.; Nilova, V. K.; Nazarkina, Ya. I.; Lavrent'ev, V. K.; Valueva, S. V.; Kipper, A. I.; Kopeikin, V. V.

    2006-07-15

    The sorption and desorption of poly(vinylpyrrolidone)-Se{sup 0} (PVP-Se{sup 0}) nanoparticles on gel films of cellulose Acetobacter xylinum (CAX) are investigated. It is revealed that the hydrodynamic radius R{sub h} of PVP-Se{sup 0} nanoparticles decreases from 57 nm in the initial solution (without CAX gel films) to 25 nm after the sorption of nanostructures on gel films and then increases to approximately 100 nm after the desorption of nanoparticles with water from dry samples of the CAX gel film-PVP-Se{sup 0} nanocomposite. It is found that selenium atoms do not penetrate into crystallites of the cellulose nanofibrils and replace water molecules sorbed by the primary hydroxyl groups of their walls. Poly(vinylpyrrolidone)-Se{sup 0} nanoclusters differ in the number and size upon their sorption inside the cellulose gel film and on the film surface.

  18. Behavior of freezable bound water in the bacterial cellulose produced by Acetobacter xylinum: an approach using thermoporosimetry.

    PubMed

    Kaewnopparat, Sanae; Sansernluk, Kamonlawat; Faroongsarng, Damrongsak

    2008-01-01

    The aim of the study is to examine thermal behavior of water within reticulated structure of bacterial cellulose (BC) films by sub-ambient differential scanning calorimetry (DSC). BC films with different carbon source, either manitol (BC (a)) or glycerol (BC (b)), were produced by Acetobacter xylinum using Hestrin and Shramm culture medium under static condition at 30 +/- 0.2 degrees C for 3 days. BC samples were characterized by electron scanning microscopy and X-ray diffraction spectroscopy. The pore analysis was done by B.H.J. nitrogen adsorption. The pre-treated with 100% relative humidity, at 30.0 +/- 0.2 degrees C for 7 days samples were subjected to a between 25 and -150 degrees C-cooling-heating cycle of DSC at 5.00 degrees C/min rate. The pre-treated samples were also hydrated by adding 1 mul of water and thermally run with identical conditions. It is observed that cellulose fibrils of BC (a) were thinner and reticulated to form slightly smaller porosity than those of BC (b). They exhibited slightly but non-significantly different crystalline features. The freezable bound water behaved as a water confinement within pores rather than a solvent of polymer which is possible to use thermoporosimetry based on Gibb-Thomson equation to approach pore structure of BC. In comparison with nitrogen adsorption, it was found that thermoporosimetry underestimated the BC porosity, i.e., the mean diameters of 23.0 nm vs. 27.8 nm and 27.9 nm vs. 33.9 nm for BC (a) and BC (b), respectively, by thermoporosimetry vs. B.H.J. nitrogen adsorption. It may be due to large non-freezable water fraction interacting with cellulose, and the validity of pore range based on thermodynamic assumptions of Gibb-Thomson theory.

  19. Phosphodiesterase A1, a regulator of cellulose synthesis in Acetobacter xylinum, is a heme-based sensor.

    PubMed

    Chang, A L; Tuckerman, J R; Gonzalez, G; Mayer, R; Weinhouse, H; Volman, G; Amikam, D; Benziman, M; Gilles-Gonzalez, M A

    2001-03-27

    The phosphodiesterase A1 protein of Acetobacter xylinum, AxPDEA1, is a key regulator of bacterial cellulose synthesis. This phosphodiesterase linearizes cyclic bis(3'-->5')diguanylic acid, an allosteric activator of the bacterial cellulose synthase, to the ineffectual pGpG. Here we show that AxPDEA1 contains heme and is regulated by reversible binding of O(2) to the heme. Apo-AxPDEA1 has less than 2% of the phosphodiesterase activity of holo-AxPDEA1, and reconstitution with hemin restores full activity. O(2) regulation is due to deoxyheme being a better activator than oxyheme. AxPDEA1 is homologous to the Escherichia coli direct oxygen sensor protein, EcDos, over its entire length and is homologous to the FixL histidine kinases over only a heme-binding PAS domain. The properties of the heme-binding domain of AxPDEA1 are significantly different from those of other O(2)-responsive heme-based sensors. The rate of AxPDEA1 autoxidation (half-life > 12 h) is the slowest observed so far for this type of heme protein fold. The O(2) affinity of AxPDEA1 (K(d) approximately 10 microM) is comparable to that of EcDos, but the rate constants for O(2) association (k(on) = 6.6 microM(-)(1) s(-)(1)) and dissociation (k(off) = 77 s(-)(1)) are 2000 times higher. Our results illustrate the versatility of signal transduction mechanisms for the heme-PAS class of O(2) sensors and provide the first example of O(2) regulation of a second messenger.

  20. Production of nano bacterial cellulose from waste water of candied jujube-processing industry using Acetobacter xylinum.

    PubMed

    Li, Zheng; Wang, Lifen; Hua, Jiachuan; Jia, Shiru; Zhang, Jianfei; Liu, Hao

    2015-04-20

    The work is aimed to investigate the suitability of waste water of candied jujube-processing industry for the production of bacterial cellulose (BC) by Gluconacetobacter xylinum CGMCC No.2955 and to study the structure properties of bacterial cellulose membranes. After acid pretreatment, the glucose of hydrolysate was higher than that of waste water of candied jujube. The volumetric yield of bacterial cellulose in hydrolysate was 2.25 g/L, which was 1.5-folds of that in waste water of candied jujube. The structures indicated that the fiber size distribution was 3-14 nm in those media with an average diameter being around 5.9 nm. The crystallinity index of BC from pretreatment medium was lower than that of without pretreatment medium and BCs from various media had similar chemical binding. Ammonium citrate was a key factor for improving production yield and the crystallinity index of BC. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Three cdg Operons Control Cellular Turnover of Cyclic Di-GMP in Acetobacter xylinum: Genetic Organization and Occurrence of Conserved Domains in Isoenzymes

    PubMed Central

    Tal, Rony; Wong, Hing C.; Calhoon, Roger; Gelfand, David; Fear, Anna Lisa; Volman, Gail; Mayer, Raphael; Ross, Peter; Amikam, Dorit; Weinhouse, Haim; Cohen, Avital; Sapir, Shai; Ohana, Patricia; Benziman, Moshe

    1998-01-01

    Cyclic di-GMP (c-di-GMP) is the specific nucleotide regulator of β-1,4-glucan (cellulose) synthase in Acetobacter xylinum. The enzymes controlling turnover of c-di-GMP are diguanylate cyclase (DGC), which catalyzes its formation, and phosphodiesterase A (PDEA), which catalyzes its degradation. Following biochemical purification of DGC and PDEA, genes encoding isoforms of these enzymes have been isolated and found to be located on three distinct yet highly homologous operons for cyclic diguanylate, cdg1, cdg2, and cdg3. Within each cdg operon, a pdeA gene lies upstream of a dgc gene. cdg1 contains two additional flanking genes, cdg1a and cdg1d. cdg1a encodes a putative transcriptional activator, similar to AadR of Rhodopseudomonas palustris and FixK proteins of rhizobia. The deduced DGC and PDEA proteins have an identical motif structure of two lengthy domains in their C-terminal regions. These domains are also present in numerous bacterial proteins of undefined function. The N termini of the DGC and PDEA deduced proteins contain putative oxygen-sensing domains, based on similarity to domains on bacterial NifL and FixL proteins, respectively. Genetic disruption analyses demonstrated a physiological hierarchy among the cdg operons, such that cdg1 contributes 80% of cellular DGC and PDEA activities and cdg2 and cdg3 contribute 15 and 5%, respectively. Disruption of dgc genes markedly reduced in vivo cellulose production, demonstrating that c-di-GMP controls this process. PMID:9721278

  2. Three cdg operons control cellular turnover of cyclic di-GMP in Acetobacter xylinum: genetic organization and occurrence of conserved domains in isoenzymes.

    PubMed

    Tal, R; Wong, H C; Calhoon, R; Gelfand, D; Fear, A L; Volman, G; Mayer, R; Ross, P; Amikam, D; Weinhouse, H; Cohen, A; Sapir, S; Ohana, P; Benziman, M

    1998-09-01

    Cyclic di-GMP (c-di-GMP) is the specific nucleotide regulator of beta-1,4-glucan (cellulose) synthase in Acetobacter xylinum. The enzymes controlling turnover of c-di-GMP are diguanylate cyclase (DGC), which catalyzes its formation, and phosphodiesterase A (PDEA), which catalyzes its degradation. Following biochemical purification of DGC and PDEA, genes encoding isoforms of these enzymes have been isolated and found to be located on three distinct yet highly homologous operons for cyclic diguanylate, cdg1, cdg2, and cdg3. Within each cdg operon, a pdeA gene lies upstream of a dgc gene. cdg1 contains two additional flanking genes, cdg1a and cdg1d. cdg1a encodes a putative transcriptional activator, similar to AadR of Rhodopseudomonas palustris and FixK proteins of rhizobia. The deduced DGC and PDEA proteins have an identical motif structure of two lengthy domains in their C-terminal regions. These domains are also present in numerous bacterial proteins of undefined function. The N termini of the DGC and PDEA deduced proteins contain putative oxygen-sensing domains, based on similarity to domains on bacterial NifL and FixL proteins, respectively. Genetic disruption analyses demonstrated a physiological hierarchy among the cdg operons, such that cdg1 contributes 80% of cellular DGC and PDEA activities and cdg2 and cdg3 contribute 15 and 5%, respectively. Disruption of dgc genes markedly reduced in vivo cellulose production, demonstrating that c-di-GMP controls this process.

  3. Nature of plant stimulators in the production of Acetobacter xylinum ({open_quotes}Tea fungas{close_quotes}) biofilm used in skin therapy

    SciTech Connect

    Fontana, J.D.; Franco, V.C.; Lyra, I.N.; De Souza, A.M.; De Souza, S.

    1991-12-31

    Caffeine and related xanthines were identified as potent stimulators for the bacterial cellulose production in A. xylinum. These compounds are present in several plants whose infusions are useful as culture-medium supplements for this acetobacterium. The proposed target for these native purine-like inhibitory substances is the novel diguanyl nucleotide phosphodiesterase(s) that participates in the bacterial cellulogenic complex.

  4. Cloning of the Membrane-Bound Aldehyde Dehydrogenase Gene of Acetobacter polyoxogenes and Improvement of Acetic Acid Production by Use of the Cloned Gene

    PubMed Central

    Fukaya, Masahiro; Tayama, Kenji; Tamaki, Toshimi; Tagami, Haruko; Okumura, Hajime; Kawamura, Yoshiya; Beppu, Teruhiko

    1989-01-01

    A genomic clone bank of Acetobacter polyoxogenes NBI1028 constructed in Escherichia coli by use of the expression vector pUC18 was screened with antibody raised against membrane-bound aldehyde dehydrogenase (ALDH; 75 kilodaltons [kDa]) from A. polyoxogenes NBI1028. A clone that synthesized a 41-kDa protein cross-reactive with anti-ALDH antibody was isolated. For cloning of the full-length ALDH structural gene, a cosmid gene bank was screened by Southern blot hybridization with the cloned DNA as a probe, and subcloning from the positive cosmid clone was performed with shuttle vector pMV24. Plasmid pAL25, containing the full-length ALDH structural gene, was isolated and expressed in both E. coli and Acetobacter aceti to produce a fused protein (78 kDa) with a short NH2-terminal β-galactosidase peptide. pAL25 conferred ALDH production on a mutant of A. aceti lacking the enzyme activity. Transformation of A. aceti subsp. xylinum NBI2099 with pAL25 caused 2- and 1.4-fold increases in the production rate and in the maximum concentration of acetic acid in submerged fermentation, respectively. Images PMID:16347820

  5. Acetobacter intermedius, sp. nov.

    PubMed

    Boesch, C; Trcek, J; Sievers, M; Teuber, M

    1998-03-01

    Strains of a new species in the genus Acetobacter, for which we propose the name A. intermedius sp. nov., were isolated and characterized in pure culture from different sources (Kombucha beverage, cider vinegar, spirit vinegar) and different countries (Switzerland, Slovenia). The isolated strains grow in media with 3% acetic acid and 3% ethanol as does A. europaeus, do, however, not require acetic acid for growth. These characteristics phenotypically position A. intermedius between A. europaeus and A. xylinus, DNA-DNA hybridizations of A. intermedius-DNA with DNA of the type strains of Acetobacter europaeus, A. xylinus, A. aceti, A. hansenii, A. liquefaciens, A. methanolicus, A. pasteurianus, A. diazotrophicus, Gluconobacter oxydans and Escherichia coli HB 101 indicated less than 60% DNA similarity. The important features of the new species are described. Acetobacter intermedius strain TF2 (DSM11804) isolated from the liquid phase of a tea fungus beverage (Kombucha) is the type strain.

  6. The nitrogen requirements of Gluconobacter, Acetobacter and Frateuria.

    PubMed

    Gosselé, F; Van den Mooter, M; Verdonck, L; Swings, J; De Ley, J

    1981-01-01

    The nitrogen requirements of 96 Gluconobacter, 55 Acetobacter and 7 Frateuria strains were examined. Only some Frateuria strains were able to grow on 0.5% yeast extract broth or 0.5% peptone broth. In the presence of D-glucose or D-mannitol as a carbon source, ammonium was used as the sole source of nitrogen by all three genera. With ethanol, only a few Acetobacter strains grew on ammonium as a sole nitrogen source. Single L-amino acids cannot serve as a sole source of carbon and nitrogen for growth of Gluconobacter, Acetobacter or Frateuria. The single L-amino acids which were used by most strains as a sole nitrogen source for growth are: asparagine, aspartic acid, glutamine, glutamic acid, proline and alanine. Some Acetobacter and Gluconobacter strains deaminated alanine, asparagine, glutamic acid, threonine, serine and proline. No Frateuria strain was able to develop on cysteine, glycine, threonine or tryptophan as a sole source of nitrogen for growth. An inhibitory effect of valine may explain the absence of growth on this amino acid. No amino acid is "essential" for Gluconobacter, Acetobacter or Frateuria.

  7. Structure of Acetobacter cellulose composites in the hydrated state.

    PubMed

    Astley, O M; Chanliaud, E; Donald, A M; Gidley, M J

    2001-10-22

    The structure of composites produced by the bacterium Acetobacter xylinus have been studied in their natural, hydrated, state. Small-angle X-ray diffraction and environmental scanning electron microscopy has shown that the ribbons have a width of 500 A and contain smaller semi-crystalline cellulose microfibrils with an essentially rectangular cross-section of approximately 10 x 160 A(2). Incubation of Acetobacter in xyloglucan or pectin results in no changes in the size of either the microfibrils or the ribbons. Changes in the cellulose crystals are seen upon dehydration of the material, resulting in either a reduction in crystal size or an increase in crystal disorder.

  8. Acetobacter lambici sp. nov., isolated from fermenting lambic beer.

    PubMed

    Spitaels, Freek; Li, Leilei; Wieme, Anneleen; Balzarini, Tom; Cleenwerck, Ilse; Van Landschoot, Anita; De Vuyst, Luc; Vandamme, Peter

    2014-04-01

    An acetic acid bacterium, strain LMG 27439(T), was isolated from fermenting lambic beer. The cells were Gram-stain-negative, motile rods, catalase-positive and oxidase-negative. Analysis of the 16S rRNA gene sequence revealed the strain was closely related to Acetobacter okinawensis (99.7 % 16S rRNA gene sequence similarity with the type strain of this species), A. ghanensis (99.6 %), A. syzygii (99.6 %), A. fabarum (99.4 %) and A. lovaniensis (99.2 %). DNA-DNA hybridization with the type strains of these species revealed moderate DNA-DNA hybridization values (31-45 %). Strain LMG 27439(T) was unable to grow on glycerol or methanol as the sole carbon source, on yeast extract with 10 % ethanol or on glucose-yeast extract medium at 37 °C. It did not produce acid from l-arabinose, d-galactose or d-mannose, nor did it produce 2-keto-d-gluconic acid, 5-keto-d-gluconic acid or 2,5-diketo-d-gluconic acid from d-glucose. It did not grow on ammonium as the sole nitrogen source and ethanol as the sole carbon source. These genotypic and phenotypic data distinguished strain LMG 27439(T) from established species of the genus Acetobacter, and therefore we propose this strain represents a novel species of the genus Acetobacter. The name Acetobacter lambici sp. nov. is proposed, with LMG 27439(T) ( = DSM 27328(T)) as the type strain.

  9. Draft Genome Sequence of Acetobacter aceti Strain 1023, a Vinegar Factory Isolate

    PubMed Central

    Hung, John E.; Mill, Christopher P.; Clifton, Sandra W.; Magrini, Vincent; Bhide, Ketaki; Francois, Julie A.; Ransome, Aaron E.; Fulton, Lucinda; Thimmapuram, Jyothi; Wilson, Richard K.

    2014-01-01

    The genome sequence of Acetobacter aceti 1023, an acetic acid bacterium adapted to traditional vinegar fermentation, comprises 3.0 Mb (chromosome plus plasmids). A. aceti 1023 is closely related to the cocoa fermenter Acetobacter pasteurianus 386B but possesses many additional insertion sequence elements. PMID:24903876

  10. Whole-genome analyses reveal genetic instability of Acetobacter pasteurianus

    PubMed Central

    Azuma, Yoshinao; Hosoyama, Akira; Matsutani, Minenosuke; Furuya, Naoko; Horikawa, Hiroshi; Harada, Takeshi; Hirakawa, Hideki; Kuhara, Satoru; Matsushita, Kazunobu; Fujita, Nobuyuki; Shirai, Mutsunori

    2009-01-01

    Acetobacter species have been used for brewing traditional vinegar and are known to have genetic instability. To clarify the mutability, Acetobacter pasteurianus NBRC 3283, which forms a multi-phenotype cell complex, was subjected to genome DNA sequencing. The genome analysis revealed that there are more than 280 transposons and five genes with hyper-mutable tandem repeats as common features in the genome consisting of a 2.9-Mb chromosome and six plasmids. There were three single nucleotide mutations and five transposon insertions in 32 isolates from the cell complex. The A. pasteurianus hyper-mutability was applied for breeding a temperature-resistant strain grown at an unviable high-temperature (42°C). The genomic DNA sequence of a heritable mutant showing temperature resistance was analyzed by mutation mapping, illustrating that a 92-kb deletion and three single nucleotide mutations occurred in the genome during the adaptation. Alpha-proteobacteria including A. pasteurianus consists of many intracellular symbionts and parasites, and their genomes show increased evolution rates and intensive genome reduction. However, A. pasteurianus is assumed to be a free-living bacterium, it may have the potentiality to evolve to fit in natural niches of seasonal fruits and flowers with other organisms, such as yeasts and lactic acid bacteria. PMID:19638423

  11. Study of nano-fiber cellulose production by Glucanacetobacter xylinum ATCC 10245.

    PubMed

    Norouzian, D; Farhangi, A; Tolooei, S; Saffari, Z; Mehrabi, M R; Chiani, M; Ghassemi, S; Farahnak, M; Akbarzadeh, A

    2011-08-01

    Bacterial Celluloses (BC) are gaining importance in research and commerce due to numerous factors affecting the bacterial cellulose characteristics and application in different industries. The aim of the present study was to produce bacterial cellulose in different media using different cultivation vessels. Bacterial cellulose was produced by static cultivation of Glucanacetobacter xylinum ATCC 10245 in different culture media such as Brain Heart Agar, Luria Bertani Agar /Broth, Brain Heart Infusion, Hestrin-Schramm and medium no. 125. Cultivation of bacterium was conducted in various culture vessels with different surface area. The cellulose membrane was treated and purified with a 0.1 M NaOH solution at 90 degreesC for 30 min and dried by a freeze- drier at -40 degreesC to obtain BC. The prepared bacterial cellulose was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD). The amount of produced BC was related directly to the surface area of culture vessels.

  12. Limited Genetic Diversity in the Endophytic Sugarcane Bacterium Acetobacter diazotrophicus

    PubMed Central

    Caballero-Mellado, Jesus; Martinez-Romero, Esperanza

    1994-01-01

    Acetobacter diazotrophicus isolates that originated from different sugarcane cultivars growing in diverse geographic regions of Mexico and Brazil were shown to have limited genetic diversity. Measurements of polymorphism in the electrophoretic mobilities of metabolic enzymes revealed that the mean genetic diversity per enzyme locus (among the four electrophoretic types distinguished) was 0.064. The results of the genetic analysis indicate that the genetic structure of A. diazotrophicus is clonal, with one largely predominant clone. Plasmids were present in 20 of 24 isolates, and the molecular sizes of the plasmids ranged from 2.0 to 170 kb. Two plasmids (a 20- to 24-kb plasmid detected in all 20 plasmid-containing isolates and a 170-kb plasmid observed in 14 isolates) were highly conserved among the isolates examined. Regardless of the presence of plasmids, all of the isolates shared a common pattern of nif structural gene organization on the chromosome. Images PMID:16349254

  13. Novel nitrogen-fixing Acetobacter nitrogenifigens sp. nov., isolated from Kombucha tea.

    PubMed

    Dutta, Debasree; Gachhui, Ratan

    2006-08-01

    The four nitrogen-fixing bacteria so far described in the family Acetobacteraceae belong to the genera Gluconacetobacter and Acetobacter. Nitrogen-fixing bacterial strain RG1(T) was isolated from Kombucha tea and, based on the phylogenetic analysis of 16S rRNA gene sequence which is supported by a high bootstrap value, was found to belong to the genus Acetobacter. Strain RG1(T) differed from Acetobacter aceti, the nearest member with a 16S rRNA gene sequence similarity of 98.2 %, and type strains of other Acetobacter species with regard to several characteristics of growth features in culture media, growth in nitrogen-free medium, production of gamma-pyrone from glucose and dihydroxyacetone from glycerol. Strain RG1(T) utilized maltose, glycerol, sorbitol, fructose, galactose, arabinose and ethanol, but not methanol as a carbon source. These results, along with electrophoretic mobility patterns of nine metabolic enzymes, suggest that strain RG1(T) represents a novel nitrogen-fixing species. The ubiquinone present was Q-9 and DNA G+C content was 64.1 mol%. Strain RG1(T) exhibited a low value of 2-24 % DNA-DNA relatedness to the type strains of related acetobacters, which placed it as a separate taxon. On the basis of this data, the name Acetobacter nitrogenifigens sp. nov. is proposed, with the type strain RG1(T) (=MTCC 6912(T)=LMG 23498(T)).

  14. Anticorrosive Influence of Acetobacter aceti Biofilms on Carbon Steel

    NASA Astrophysics Data System (ADS)

    France, Danielle Cook

    2016-09-01

    Microbiologically influenced corrosion (MIC) of carbon steel infrastructure is an emerging environmental and cost issue for the ethanol fuel industry, yet its examination lacks rigorous quantification of microbiological parameters that could reveal effective intervention strategies. To quantitatively characterize the effect of cell concentration on MIC of carbon steel, numbers of bacteria exposed to test coupons were systematically controlled to span four orders of magnitude throughout a seven-day test. The bacterium studied, Acetobacter aceti, has been found in ethanol fuel environments and can convert ethanol to the corrosive species acetic acid. A. aceti biofilms formed during the test were qualitatively evaluated with fluorescence microscopy, and steel surfaces were characterized by scanning electron microscopy. During exposure, biofilms developed more quickly, and test reactor pH decreased at a faster rate, when cell exposure was higher. Resulting corrosion rates, however, were inversely proportional to cell exposure, indicating that A. aceti biofilms are able to protect carbon steel surfaces from corrosion. This is a novel demonstration of corrosion inhibition by an acid-producing bacterium that occurs naturally in corrosive environments. Mitigation techniques for MIC that harness the power of microbial communities have the potential to be scalable, inexpensive, and green solutions to industrial problems.

  15. Natural Endophytic Occurrence of Acetobacter diazotrophicus in Pineapple Plants.

    PubMed

    Tapia-Hernández; Bustillos-Cristales; Jiménez-Salgado; Caballero-Mellado; Fuentes-Ramírez

    2000-01-01

    The presence of endophytic Acetobacter diazotrophicus was tested for pineapple plants (Ananas comosus [L.] Merr.) grown in the field. Diazotrophic bacteria were isolated from the inner tissues of surface sterilized roots, stems, and leaves of pineapple plants. Phenotypic tests permitted the selection of presumptive nitrogen-fixing A. diazotrophicus isolates. Restriction fragment length polymorphisms (RFLPs) of small subunit (SSU) rDNA using total DNA digested with endonuclease SphI and with endonuclease NcoI, hybridizations of RNA with an A. diazotrophicus large subunit (LSU) rRNA specific probe, as well as patterns in denaturing protein electrophoresis (SDS-PAGE) and multilocus enzyme tests allowed the identification of A. diazotrophicus isolates. High frequencies of isolation were obtained from propagative buds that had not been nitrogen-fertilized, and lower frequencies from 3-month-old plants that had been nitrogen-fertilized. No isolates were recovered from 5- to 7-month-old nitrogen-fertilized plants. All the A. diazotrophicus isolates recovered from pineapple plants belonged to the multilocus genotype which shows the most extensive distribution among all host species previously analyzed.

  16. Assessment of the contribution of cocoa-derived strains of Acetobacter ghanensis and Acetobacter senegalensis to the cocoa bean fermentation process through a genomic approach.

    PubMed

    Illeghems, Koen; Pelicaen, Rudy; De Vuyst, Luc; Weckx, Stefan

    2016-09-01

    Acetobacter ghanensis LMG 23848(T) and Acetobacter senegalensis 108B are acetic acid bacteria that originate from a spontaneous cocoa bean heap fermentation process and that have been characterised as strains with interesting functionalities through metabolic and kinetic studies. As there is currently little genetic information available for these species, whole-genome sequencing of A. ghanensis LMG 23848(T) and A. senegalensis 108B and subsequent data analysis was performed. This approach not only revealed characteristics such as the metabolic potential and genomic architecture, but also allowed to indicate the genetic adaptations related to the cocoa bean fermentation process. Indeed, evidence was found that both species possessed the genetic ability to be involved in citrate assimilation and displayed adaptations in their respiratory chain that might improve their competitiveness during the cocoa bean fermentation process. In contrast, other properties such as the dependence on glycerol or mannitol and lactate as energy sources or a less efficient acid stress response may explain their low competitiveness. The presence of a gene coding for a proton-translocating transhydrogenase in A. ghanensis LMG 23848(T) and the genes involved in two aromatic compound degradation pathways in A. senegalensis 108B indicate that these strains have an extended functionality compared to Acetobacter species isolated from other ecosystems.

  17. Draft Genome Sequence of Acetobacter malorum CECT 7742, a Strain Isolated from Strawberry Vinegar

    PubMed Central

    Sainz, Florencia; Torija, María Jesús

    2016-01-01

    The present article reports the draft genome sequence of the strain Acetobacter malorum CECT 7742, an acetic acid bacterium isolated from strawberry vinegar. This species is characterized by the production of d-gluconic acid from d-glucose, which it further metabolizes to keto-d-gluconic acids. PMID:27340078

  18. Genetic Structure of Acetobacter diazotrophicus Populations and Identification of a New Genetically Distant Group

    PubMed Central

    Caballero-Mellado, J.; Fuentes-Ramirez, L. E.; Reis, V. M.; Martinez-Romero, E.

    1995-01-01

    A total of 55 isolates of Acetobacter diazotrophicus recovered from diverse sucrose-rich host plants and from mealybugs associated with sugarcane plants were characterized by the electrophoretic mobilities of 12 metabolic enzymes. We identified seven different electrophoretic types (ETs), six of which are closely related within a genetic distance of 0.195 and exhibit high DNA-DNA homology. The seventh ET was largely divergent, separated at a genetic distance of 0.53, and had only 54% DNA homology to the reference strain. Strains corresponding to ET 7 could represent a distinct nitrogen-fixing species of the genus Acetobacter. More genetic diversity was found in isolates from Brazil than in those from Mexico, probably due to the very different crop nitrogen fertilization levels used. PMID:16535102

  19. Optimization of lactobionic acid production by Acetobacter orientalis isolated from Caucasian fermented milk, "Caspian Sea yogurt".

    PubMed

    Kiryu, Takaaki; Yamauchi, Kouhei; Masuyama, Araki; Ooe, Kenichi; Kimura, Takashi; Kiso, Taro; Nakano, Hirofumi; Murakami, Hiromi

    2012-01-01

    We have reported that lactobionic acid is produced from lactose by Acetobacter orientalis in traditional Caucasian fermented milk. To maximize the application of lactobionic acid, we investigated favorable conditions for the preparation of resting A. orientalis cells and lactose oxidation. The resting cells, prepared under the most favorable conditions, effectively oxidized 2-10% lactose at 97.2 to 99.7 mol % yield.

  20. Oxidation of Metabolites Highlights the Microbial Interactions and Role of Acetobacter pasteurianus during Cocoa Bean Fermentation

    PubMed Central

    Moens, Frédéric; Lefeber, Timothy

    2014-01-01

    Four cocoa-specific acetic acid bacterium (AAB) strains, namely, Acetobacter pasteurianus 386B, Acetobacter ghanensis LMG 23848T, Acetobacter fabarum LMG 24244T, and Acetobacter senegalensis 108B, were analyzed kinetically and metabolically during monoculture laboratory fermentations. A cocoa pulp simulation medium (CPSM) for AAB, containing ethanol, lactic acid, and mannitol, was used. All AAB strains differed in their ethanol and lactic acid oxidation kinetics, whereby only A. pasteurianus 386B performed a fast oxidation of ethanol and lactic acid into acetic acid and acetoin, respectively. Only A. pasteurianus 386B and A. ghanensis LMG 23848T oxidized mannitol into fructose. Coculture fermentations with A. pasteurianus 386B or A. ghanensis LMG 23848T and Lactobacillus fermentum 222 in CPSM for lactic acid bacteria (LAB) containing glucose, fructose, and citric acid revealed oxidation of lactic acid produced by the LAB strain into acetic acid and acetoin that was faster in the case of A. pasteurianus 386B. A triculture fermentation with Saccharomyces cerevisiae H5S5K23, L. fermentum 222, and A. pasteurianus 386B, using CPSM for LAB, showed oxidation of ethanol and lactic acid produced by the yeast and LAB strain, respectively, into acetic acid and acetoin. Hence, acetic acid and acetoin are the major end metabolites of cocoa bean fermentation. All data highlight that A. pasteurianus 386B displayed beneficial functional roles to be used as a starter culture, namely, a fast oxidation of ethanol and lactic acid, and that these metabolites play a key role as substrates for A. pasteurianus in its indispensable cross-feeding interactions with yeast and LAB during cocoa bean fermentation. PMID:24413595

  1. Acetobacter sicerae sp. nov., isolated from cider and kefir, and identification of species of the genus Acetobacter by dnaK, groEL and rpoB sequence analysis.

    PubMed

    Li, Leilei; Wieme, Anneleen; Spitaels, Freek; Balzarini, Tom; Nunes, Olga C; Manaia, Célia M; Van Landschoot, Anita; De Vuyst, Luc; Cleenwerck, Ilse; Vandamme, Peter

    2014-07-01

    Five acetic acid bacteria isolates, awK9_3, awK9_4 ( = LMG 27543), awK9_5 ( = LMG 28092), awK9_6 and awK9_9, obtained during a study of micro-organisms present in traditionally produced kefir, were grouped on the basis of their MALDI-TOF MS profile with LMG 1530 and LMG 1531(T), two strains currently classified as members of the genus Acetobacter. Phylogenetic analysis based on nearly complete 16S rRNA gene sequences as well as on concatenated partial sequences of the housekeeping genes dnaK, groEL and rpoB indicated that these isolates were representatives of a single novel species together with LMG 1530 and LMG 1531(T) in the genus Acetobacter, with Acetobacter aceti, Acetobacter nitrogenifigens, Acetobacter oeni and Acetobacter estunensis as nearest phylogenetic neighbours. Pairwise similarity of 16S rRNA gene sequences between LMG 1531(T) and the type strains of the above-mentioned species were 99.7%, 99.1%, 98.4% and 98.2%, respectively. DNA-DNA hybridizations confirmed that status, while amplified fragment length polymorphism (AFLP) and random amplified polymorphic DNA (RAPD) data indicated that LMG 1531(T), LMG 1530, LMG 27543 and LMG 28092 represent at least two different strains of the novel species. The major fatty acid of LMG 1531(T) and LMG 27543 was C18 : 1ω7c. The major ubiquinone present was Q-9 and the DNA G+C contents of LMG 1531(T) and LMG 27543 were 58.3 and 56.7 mol%, respectively. The strains were able to grow on D-fructose and D-sorbitol as a single carbon source. They were also able to grow on yeast extract with 30% D-glucose and on standard medium with pH 3.6 or containing 1% NaCl. They had a weak ability to produce acid from d-arabinose. These features enabled their differentiation from their nearest phylogenetic neighbours. The name Acetobacter sicerae sp. nov. is proposed with LMG 1531(T) ( = NCIMB 8941(T)) as the type strain. © 2014 IUMS.

  2. Acetobacter strains isolated during the acetification of blueberry (Vaccinium corymbosum L.) wine.

    PubMed

    Hidalgo, C; García, D; Romero, J; Mas, A; Torija, M J; Mateo, E

    2013-09-01

    Highbush blueberries (Vaccinium corymbosum L.) are known to have positive health benefits. The production of blueberry vinegar is one method to preserve this seasonal fruit and allow extended consumption. In this study, blueberry wine acetification was performed with naturally occurring micro-organisms and with an inoculated Acetobacter cerevisiae strain. Acetifications were carried out in triplicate using the Schützenbach method. The successful spontaneous processes took up to 66% more time than the processes involving inoculation. The isolation of acetic acid bacteria (AAB) and the analysis of these AAB using molecular methods allowed the identification of the main genotypes responsible of the blueberry acetification. Although the Acet. cerevisiae strain was the predominant strain isolated from the inoculated process samples, Acetobacter pasteurianus was isolated from samples for both processes and was the only species present in the spontaneous acetification samples. To the best of our knowledge, this is the first report describing the identification and variability of AAB isolated during blueberry acetification. The isolated Acet. pasteurianus strains could be used for large-scale blueberry vinegar production or as a starter culture in studies of other vinegar production methods.

  3. Comparative Proteome of Acetobacter pasteurianus Ab3 During the High Acidity Rice Vinegar Fermentation.

    PubMed

    Wang, Zhe; Zang, Ning; Shi, Jieyan; Feng, Wei; Liu, Ye; Liang, Xinle

    2015-12-01

    As a traditional Asian food for several centuries, vinegar is known to be produced by acetic acid bacteria. The Acetobacter species is the primary starter for vinegar fermentation and has evolutionarily acquired acetic acid resistance, in which Acetobacter pasteurianus Ab3 is routinely used for industrial production of rice vinegar with a high acidity (9 %, w/v). In contrast to the documented short-term and low acetic acid effects on A. pasteurianus, here we investigated the molecular and cellular signatures of long-term and high acetic acid responses by proteomic profiling with bidimensional gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF/MS) analyses. Protein spots of interest were selected based on the threshold ANOVA p value of 0.05 and minimal twofold of differential expression, leading to the identification of 26 proteins that are functionally enriched in oxidoreductase activity, cell membrane, and metabolism. The alterations in protein functioning in respiratory chain and protein denaturation may underlay cellular modifications at the outer membrane. Significantly, we found that at higher acidity fermentation phase, the A. pasteurianus Ab3 cells would adapt to distinct physiological processes from that of an ordinary vinegar fermentation with intermediate acidity, indicating increasing energy requirement and dependency of membrane integrity during the transition of acetic acid production. Together, our study provided new insights into the adaptation mechanisms in A. pasteurianus to high acetic acid environments and yield novel regulators and key pathways during the development of acetic acid resistance.

  4. New insights into the mechanisms of acetic acid resistance in Acetobacter pasteurianus using iTRAQ-dependent quantitative proteomic analysis.

    PubMed

    Xia, Kai; Zang, Ning; Zhang, Junmei; Zhang, Hong; Li, Yudong; Liu, Ye; Feng, Wei; Liang, Xinle

    2016-12-05

    Acetobacter pasteurianus is the main starter in rice vinegar manufacturing due to its remarkable abilities to resist and produce acetic acid. Although several mechanisms of acetic acid resistance have been proposed and only a few effector proteins have been identified, a comprehensive depiction of the biological processes involved in acetic acid resistance is needed. In this study, iTRAQ-based quantitative proteomic analysis was adopted to investigate the whole proteome of different acidic titers (3.6, 7.1 and 9.3%, w/v) of Acetobacter pasteurianus Ab3 during the vinegar fermentation process. Consequently, 1386 proteins, including 318 differentially expressed proteins (p<0.05), were identified. Compared to that in the low titer circumstance, cells conducted distinct biological processes under high acetic acid stress, where >150 proteins were differentially expressed. Specifically, proteins involved in amino acid metabolic processes and fatty acid biosynthesis were differentially expressed, which may contribute to the acetic acid resistance of Acetobacter. Transcription factors, two component systems and toxin-antitoxin systems were implicated in the modulatory network at multiple levels. In addition, the identification of proteins involved in redox homeostasis, protein metabolism, and the cell envelope suggested that the whole cellular system is mobilized in response to acid stress. These findings provide a differential proteomic profile of acetic acid resistance in Acetobacter pasteurianus and have potential application to highly acidic rice vinegar manufacturing. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Coffea arabica L., a new host plant for Acetobacter diazotrophicus, and isolation of other nitrogen-fixing acetobacteria.

    PubMed Central

    Jimenez-Salgado, T; Fuentes-Ramirez, L E; Tapia-Hernandez, A; Mascarua-Esparza, M A; Martinez-Romero, E; Caballero-Mellado, J

    1997-01-01

    Acetobacter diazotrophicus was isolated from coffee plant tissues and from rhizosphere soils. Isolation frequencies ranged from 15 to 40% and were dependent on soil pH. Attempts to isolate this bacterial species from coffee fruit, from inside vesicular-arbuscular mycorrhizal fungi spores, or from mealybugs (Planococcus citri) associated with coffee plants were not successful. Other acid-producing diazotrophic bacteria were recovered with frequencies of 20% from the coffee rhizosphere. These N2-fixing isolates had some features in common with the genus Acetobacter but should not be assigned to the species Acetobacter diazotrophicus because they differed from A. diazotrophicus in morphological and biochemical traits and were largely divergent in electrophoretic mobility patterns of metabolic enzymes at coefficients of genetic distance as high as 0.950. In addition, these N2-fixing acetobacteria differed in the small-subunit rRNA restriction fragment length polymorphism patterns obtained with EcoRI, and they exhibited very low DNA-DNA homology levels, ranging from 11 to 15% with the A. diazotrophicus reference strain PAI 5T. Thus, some of the diazotrophic acetobacteria recovered from the rhizosphere of coffee plants may be regarded as N2-fixing species of the genus Acetobacter other than A. diazotrophicus. Endophytic diazotrophic bacteria may be more prevalent than previously thought, and perhaps there are many more potentially beneficial N2-fixing bacteria which can be isolated from other agronomically important crops. PMID:9293018

  6. Effects of a cellulose mask synthesized by a bacterium on facial skin characteristics and user satisfaction

    PubMed Central

    Amnuaikit, Thanaporn; Chusuit, Toon; Raknam, Panithi; Boonme, Prapaporn

    2011-01-01

    Background Cellulose masks obtained from natural sources such as bacteria are of interest as cosmetic devices for the treatment of dry skin because they not only improve hydration of the skin, but have low toxicity and are biodegradable. The aims of this study were to determine the in vivo effects of a cellulose mask obtained from Acetobacter xylinum on skin characteristics and to evaluate user satisfaction with the product. Methods Thirty healthy Thai volunteers aged 21–40 years participated in the study. The volunteers were randomly separated into a control group and an experimental group. For the control group, volunteers were assigned to apply moist towels to the face for 25 minutes. For the experimental group, the volunteers were assigned to apply the masks, ie, translucent patches which could be fitted onto the face for the same period. The following week, the groups were changed over to the alternative treatment. Skin moisture, sebum, elasticity, texture, dullness, and desquamation levels were assessed using a system used for routine skin counseling before applying the trial product and five minutes after its removal. Degree of satisfaction with use of the cellulose mask was investigated using a five-point rating scale. Results The cellulose mask increased moisture levels in the skin significantly more than moist towels (P < 0.05) after a single application. No obvious effects on other skin characteristics were found. The cellulose mask product rated around 4/5 on the satisfaction rating scale. Conclusions A single application of the trial cellulose mask enhanced moisture uptake by facial skin. Users also reported being satisfied with the trial product. PMID:22915933

  7. Effect of media components on cell growth and bacterial cellulose production from Acetobacter aceti MTCC 2623.

    PubMed

    Dayal, Manmeet Singh; Goswami, Navendu; Sahai, Anshuman; Jain, Vibhor; Mathur, Garima; Mathur, Ashwani

    2013-04-15

    Acetobacter aceti MTCC 2623 was studied as an alternative microbial source for bacterial cellulose (BC) production. Effect of media components on cell growth rate, BC production and cellulose characteristics were studied. FTIR results showed significant variations in cellulose characteristics produced by A. aceti in different media. Results have shown the role of fermentation time on crystallinity ratio of BC in different media. Further, effect of six different media components on cell growth and BC production was studied using fractional factorial design. Citric acid was found to be the most significant media component for cell growth rate (95% confidence level, R(2)=0.95). However, direct role of these parameters on cellulose production was not established (p-value>0.05). Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Binding of soluble glycoproteins from sugarcane juice to cells of Acetobacter diazotrophicus.

    PubMed

    Legaz, M E; de Armas, R; Barriguete, E; Vicente, C

    2000-09-01

    Sugarcane produces two different pools of glycoproteins containing a heterofructan as glycidic moiety, tentatively defined as high-molecular mass (HMMG) and mid-molecular mass (MMMG) glycoproteins. Both kinds of glycoproteins can be recovered in sugarcane juice. Fluorescein-labelled glycoproteins are able to bind to Acetobacter diazotrophicus cells, a natural endophyte of sugarcane. This property implies the aggregation of bacterial cells in liquid culture after addition of HMMG or MMMG. Anionic glycoproteins seem to be responsible for the binding activity whereas cationic fraction is not retained on the surface ofA. diazotrophicus. Bound HMMG is competitively desorbed by sucrose whereas MMMG is desorbed by glucosamine or fructose. On this basis, a hypothesis about the discriminatory ability of sugarcane to choose the compatible endophyte from several possible ones is proposed.

  9. Cloning, sequence analysis, and expression in Escherichia coli of the gene encoding an alpha-amino acid ester hydrolase from Acetobacter turbidans.

    PubMed

    Polderman-Tijmes, Jolanda J; Jekel, Peter A; de Vries, Erik J; van Merode, Annet E J; Floris, René; van der Laan, Jan-Metske; Sonke, Theo; Janssen, Dick B

    2002-01-01

    The alpha-amino acid ester hydrolase from Acetobacter turbidans ATCC 9325 is capable of hydrolyzing and synthesizing beta-lactam antibiotics, such as cephalexin and ampicillin. N-terminal amino acid sequencing of the purified alpha-amino acid ester hydrolase allowed cloning and genetic characterization of the corresponding gene from an A. turbidans genomic library. The gene, designated aehA, encodes a polypeptide with a molecular weight of 72,000. Comparison of the determined N-terminal sequence and the deduced amino acid sequence indicated the presence of an N-terminal leader sequence of 40 amino acids. The aehA gene was subcloned in the pET9 expression plasmid and expressed in Escherichia coli. The recombinant protein was purified and found to be dimeric with subunits of 70 kDa. A sequence similarity search revealed 26% identity with a glutaryl 7-ACA acylase precursor from Bacillus laterosporus, but no homology was found with other known penicillin or cephalosporin acylases. There was some similarity to serine proteases, including the conservation of the active site motif, GXSYXG. Together with database searches, this suggested that the alpha-amino acid ester hydrolase is a beta-lactam antibiotic acylase that belongs to a class of hydrolases that is different from the Ntn hydrolase superfamily to which the well-characterized penicillin acylase from E. coli belongs. The alpha-amino acid ester hydrolase of A. turbidans represents a subclass of this new class of beta-lactam antibiotic acylases.

  10. Putative ABC Transporter Responsible for Acetic Acid Resistance in Acetobacter aceti

    PubMed Central

    Nakano, Shigeru; Fukaya, Masahiro; Horinouchi, Sueharu

    2006-01-01

    Two-dimensional gel electrophoretic analysis of the membrane fraction of Acetobacter aceti revealed the presence of several proteins that were produced in response to acetic acid. A 60-kDa protein, named AatA, which was mostly induced by acetic acid, was prepared; aatA was cloned on the basis of its NH2-terminal amino acid sequence. AatA, consisting of 591 amino acids and containing ATP-binding cassette (ABC) sequences and ABC signature sequences, belonged to the ABC transporter superfamily. The aatA mutation with an insertion of the neomycin resistance gene within the aatA coding region showed reduced resistance to acetic acid, formic acid, propionic acid, and lactic acid, whereas the aatA mutation exerted no effects on resistance to various drugs, growth at low pH (adjusted with HCl), assimilation of acetic acid, or resistance to citric acid. Introduction of plasmid pABC101 containing aatA under the control of the Escherichia coli lac promoter into the aatA mutant restored the defect in acetic acid resistance. In addition, pABC101 conferred acetic acid resistance on E. coli. These findings showed that AatA was a putative ABC transporter conferring acetic acid resistance on the host cell. Southern blot analysis and subsequent nucleotide sequencing predicted the presence of aatA orthologues in a variety of acetic acid bacteria belonging to the genera Acetobacter and Gluconacetobacter. The fermentation with A. aceti containing aatA on a multicopy plasmid resulted in an increase in the final yield of acetic acid. PMID:16391084

  11. Acetobacter aceti Possesses a Proton Motive Force-Dependent Efflux System for Acetic Acid

    PubMed Central

    Matsushita, Kazunobu; Inoue, Taketo; Adachi, Osao; Toyama, Hirohide

    2005-01-01

    Acetic acid bacteria are obligate aerobes able to oxidize ethanol, sugar alcohols, and sugars into their corresponding acids. Among them, Acetobacter and Gluconacetobacter species have very high ethanol oxidation capacity, leading to accumulation of vast amounts of acetic acid outside the cell. Since these bacteria are able to grow in media with high concentrations of acetic acid, they must possess a specific mechanism such as an efflux pump by which they can resist the toxic effects of acetic acid. In this study, the efflux pump of Acetobacter aceti IFO 3283 was examined using intact cells and membrane vesicles. The accumulation of acetic acid/acetate in intact cells was increased by the addition of a proton uncoupler and/or cyanide, suggesting the presence of an energy-dependent efflux system. To confirm this, right-side-out and inside-out membrane vesicles were prepared from A. aceti IFO 3283, and the accumulation of acetic acid/acetate in the vesicles was examined. Upon the addition of a respiratory substrate, the accumulation of acetic acid/acetate in the right-side-out vesicles was largely decreased, while its accumulation was very much increased in the inside-out vesicles. These respiration-dependent phenomena observed in both types of membrane vesicles were all sensitive to a proton uncoupler. Acetic acid/acetate uptake in the inside-out membrane vesicles was dependent not on ATP but on the proton motive force. Furthermore, uptake was shown to be rather specific for acetic acid and to be pH dependent, because higher uptake was observed at lower pH. Thus, A. aceti IFO 3283 possesses a proton motive force-dependent efflux pump for acetic acid. PMID:15968043

  12. Determination of Dehydrogenase Activities Involved in D-Glucose Oxidation in Gluconobacter and Acetobacter Strains

    PubMed Central

    Sainz, Florencia; Jesús Torija, María; Matsutani, Minenosuke; Kataoka, Naoya; Yakushi, Toshiharu; Matsushita, Kazunobu; Mas, Albert

    2016-01-01

    Acetic acid bacteria (AAB) are known for rapid and incomplete oxidation of an extensively variety of alcohols and carbohydrates, resulting in the accumulation of organic acids as the final products. These oxidative fermentations in AAB are catalyzed by PQQ- or FAD- dependent membrane-bound dehydrogenases. In the present study, the enzyme activity of the membrane-bound dehydrogenases [membrane-bound PQQ-glucose dehydrogenase (mGDH), D-gluconate dehydrogenase (GADH) and membrane-bound glycerol dehydrogenase (GLDH)] involved in the oxidation of D-glucose and D-gluconic acid (GA) was determined in six strains of three different species of AAB (three natural and three type strains). Moreover, the effect of these activities on the production of related metabolites [GA, 2-keto-D-gluconic acid (2KGA) and 5-keto-D-gluconic acid (5KGA)] was analyzed. The natural strains belonging to Gluconobacter showed a high mGDH activity and low activity in GADH and GLDH, whereas the Acetobacter malorum strain presented low activity in the three enzymes. Nevertheless, no correlation was observed between the activity of these enzymes and the concentration of the corresponding metabolites. In fact, all the tested strains were able to oxidize D-glucose to GA, being maximal at the late exponential phase of the AAB growth (24 h), which coincided with D-glucose exhaustion and the maximum mGDH activity. Instead, only some of the tested strains were capable of producing 2KGA and/or 5KGA. In the case of Gluconobacter oxydans strains, no 2KGA production was detected which is related to the absence of GADH activity after 24 h, while in the remaining strains, detection of GADH activity after 24 h resulted in a high accumulation of 2KGA. Therefore, it is possible to choose the best strain depending on the desired product composition. Moreover, the sequences of these genes were used to construct phylogenetic trees. According to the sequence of gcd, gene coding for mGDH, Acetobacter and Komagataeibacter

  13. Immobilization of Acetobacter sp. CCTCC M209061 for efficient asymmetric reduction of ketones and biocatalyst recycling

    PubMed Central

    2012-01-01

    Background The bacterium Acetobacter sp. CCTCC M209061 is a promising whole-cell biocatalyst with exclusive anti-Prelog stereoselectivity for the reduction of prochiral ketones that can be used to make valuable chiral alcohols such as (R)-4-(trimethylsilyl)-3-butyn-2-ol. Although it has promising catalytic properties, its stability and reusability are relatively poor compared to other biocatalysts. Hence, we explored various materials for immobilizing the active cells, in order to improve the operational stability of biocatalyst. Results It was found that Ca-alginate give the best immobilized biocatalyst, which was then coated with chitosan to further improve its mechanical strength and swelling-resistance properties. Conditions were optimized for formation of reusable immobilized beads which can be used for repeated batch asymmetric reduction of 4′-chloroacetophenone. The optimized immobilized biocatalyst was very promising, with a specific activity of 85% that of the free-cell biocatalyst (34.66 μmol/min/g dw of cells for immobilized catalyst vs 40.54 μmol/min/g for free cells in the asymmetric reduction of 4′-chloroacetophenone). The immobilized cells showed better thermal stability, pH stability, solvent tolerance and storability compared with free cells. After 25 cycles reaction, the immobilized beads still retained >50% catalytic activity, which was 3.5 times higher than degree of retention of activity by free cells reused in a similar way. The cells could be recultured in the beads to regain full activity and perform a further 25 cycles of the reduction reaction. The external mass transfer resistances were negligible as deduced from Damkohler modulus Da < <1, and internal mass transfer restriction affected the reduction action but was not the principal rate-controlling step according to effectiveness factors η < 1 and Thiele modulus 0.3<∅ <1. Conclusions Ca-alginate coated with chitosan is a highly effective material for immobilization of

  14. Effect of chitosan and SO2 on viability of Acetobacter strains in wine.

    PubMed

    Valera, Maria José; Sainz, Florencia; Mas, Albert; Torija, María Jesús

    2017-04-04

    Wine spoilage is an important concern for winemakers to preserve the quality of their final product and avoid contamination throughout the production process. The use of sulphur dioxide (SO2) is highly recommended to prevent wine spoilage due to its antimicrobial activity. However, SO2 has a limited effect on the viability of acetic acid bacteria (AAB). Currently, the use of SO2 alternatives is favoured in order to reduce the use of chemicals and improve stabilization in winemaking. Chitosan is a biopolymer that is approved by the European authorities and the International Organization of Vine and Wine to be used as a fining agent and antimicrobial in wines. However, its effectiveness in AAB prevention has not been studied. Two strains of Acetobacter, adapted to high ethanol environments, were analysed in this study. Both chitosan and SO2 effects were compared in artificially contaminated wines. Both molecules reduced the metabolic activity of both AAB strains. Although AAB populations were detected by culture independent techniques, their numbers were reduced with time, and their viability decreased following the application of both products, especially with chitosan. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Acetobacter pasteurianus metabolic change induced by initial acetic acid to adapt to acetic acid fermentation conditions.

    PubMed

    Zheng, Yu; Zhang, Renkuan; Yin, Haisong; Bai, Xiaolei; Chang, Yangang; Xia, Menglei; Wang, Min

    2017-08-02

    Initial acetic acid can improve the ethanol oxidation rate of acetic acid bacteria for acetic acid fermentation. In this work, Acetobacter pasteurianus was cultured in ethanol-free medium, and energy production was found to increase by 150% through glucose consumption induced by initial acetic acid. However, oxidation of ethanol, instead of glucose, became the main energy production pathway when upon culturing ethanol containing medium. Proteome assay was used to analyze the metabolism change induced by initial acetic acid, which provided insight into carbon metabolic and energy regulation of A. pasteurianus to adapt to acetic acid fermentation conditions. Results were further confirmed by quantitative real-time PCR. In summary, decreased intracellular ATP as a result of initial acetic acid inhibition improved the energy metabolism to produce more energy and thus adapt to the acetic acid fermentation conditions. A. pasteurianus upregulated the expression of enzymes related to TCA and ethanol oxidation to improve the energy metabolism pathway upon the addition of initial acetic acid. However, enzymes involved in the pentose phosphate pathway, the main pathway of glucose metabolism, were downregulated to induce a change in carbon metabolism. Additionally, the enhancement of alcohol dehydrogenase expression promoted ethanol oxidation and strengthened the acetification rate, thereby producing a strong proton motive force that was necessary for energy production and cell tolerance to acetic acid.

  16. In vitro synthesis and properties of pectin/Acetobacter xylinus cellulose composites

    PubMed

    Chanliaud; Gidley

    1999-10-01

    Pectin and cellulose are major components of most primary cell walls, yet little is known about the way in which they interact either during assembly or in subsequent functional performance of the wall. As a mimic of cell wall assembly, we studied the formation of molecular composites formed by deposition of cellulose from Acetobacter xylinus into pectin/calcium systems, and the molecular, architectural and mechanical properties of the composites obtained. The formation of interpenetrating cellulose/pectin composite networks (as envisaged in current models for primary cell walls) required a pre-existing, but not too strong, pectin network. For pectin either in solution or strongly networked, phase separation from cellulose occurred, providing two physical models for the formation of middle lamellae. Composite networks showed no evidence of direct molecular interaction between the components, but pectin networks became more aggregated following deposition of cellulose into them. The shear strength under small deformation conditions for cellulose/pectin composites was very similar to that of cellulose alone. In contrast, under uniaxial tension, extensibility was greatly increased and stiffness decreased. These major changes were due to the effect of pectin on cellulose network architecture at deposition, as they were maintained upon removal of the pectin component. These results show that the presence and physical state of pectin at the time of cellulose deposition in muro may be a significant determinant of subsequent extensibility without compromising strength.

  17. Growth characteristics and oxidative capacity of Acetobacter aceti IFO 3281: implications for L-ribulose production.

    PubMed

    Kylmä, A K; Granström, T; Leisola, M

    2004-02-01

    We studied the growth characteristics and oxidative capacities of Acetobacter aceti IFO 3281 in batch and chemostat cultures. In batch culture, glycerol was the best growth substrate and growth on ethanol occurred only after 6 days delay, although ethanol was rapidly oxidized to acetic acid. In continuous culture, both glycerol and ethanol were good growth substrates with similar characteristics. Resting cells in a bioreactor oxidized ribitol to L-ribulose with a maximal specific rate of 1.2 g g(-1) h(-1)). The oxidation of ribitol was inhibited by ethanol but not by glycerol. Biomass yield (Y(SX); C-mmol/C-mmol) on ethanol and glycerol was low (0.21 and 0.17, respectively). In the presence of ribitol the yield was somewhat higher (0.25) with ethanol but lower (0.13) with glycerol, with respectively lower and higher CO(2) production. In chemostat cultures the oxidation rate of ribitol was unaffected by ethanol or glycerol. Cell-free extract oxidized ethanol very slowly but not ribitol; the oxidative activity was located in the cell membrane fraction. Enzymatic activities of some key metabolic enzymes were determined from steady-state chemostat with ethanol, glycerol, or ethanol/glycerol mixture as a growth limiting substrate. Based on the measured enzyme activities, metabolic pathways are proposed for ethanol and glycerol metabolism.

  18. Acetobacter pasteurianus strain AB0220: cultivability and phenotypic stability over 9 years of preservation.

    PubMed

    Gullo, Maria; Mamlouk, Dhouha; De Vero, Luciana; Giudici, Paolo

    2012-06-01

    Acetobacter species are members of the α-subclass of Proteobacteria, which harbors a large number of bacteria recalcitrant to cultivation. Strain AB0220 was isolated from a superficial acetification system and preserved for 9 years by short and long time methods. Under short time preservation it was estimated that 540.54 number of generations occurred, whereas in long time preservation conditions the number of generations was 17.40. Ethanol oxidation to acetic acid was stable and confirmed, as well as acetate assimilation during long time preservation. Cultivability checks showed persistence of phenotypic traits (growth on ethanol and methanol, growth on different carbon sources and cellulose production) over the extended preservation time. 16S rRNA gene sequences analysis showed 100 % of similarity with A. pasteurianus (Accession number GQ240636). Stability of subcultures related to the culture age and subcultures frequency, tested by ERIC/PCR, confirmed the suitability of long term preservation at least over a period of 9 years.

  19. Improving Acetic Acid Production by Over-Expressing PQQ-ADH in Acetobacter pasteurianus

    PubMed Central

    Wu, Xuefeng; Yao, Hongli; Cao, Lili; Zheng, Zhi; Chen, Xiaoju; Zhang, Min; Wei, Zhaojun; Cheng, Jieshun; Jiang, Shaotong; Pan, Lijun; Li, Xingjiang

    2017-01-01

    Pyrroquinoline quinone-dependent alcohol dehydrogenase (PQQ-ADH) is a key enzyme in the ethanol oxidase respiratory chain of acetic acid bacteria (AAB). To investigate the effect of PQQ-ADH on acetic acid production by Acetobacter pasteurianus JST-S, subunits I (adhA) and II (adhB) of PQQ-ADH were over-expressed, the fermentation parameters and the metabolic flux analysis were compared in the engineered strain and the original one. The acetic acid production was improved by the engineered strain (61.42 g L−1) while the residual ethanol content (4.18 g L−1) was decreased. Analysis of 2D maps indicated that 19 proteins were differently expressed between the two strains; of these, 17 were identified and analyzed by mass spectrometry and two-dimensional gel electrophoresis. With further investigation of metabolic flux analysis (MFA) of the pathway from ethanol and glucose, the results reveal that over-expression of PQQ-ADH is an effective way to improve the ethanol oxidation respiratory chain pathway and these can offer theoretical references for potential mechanism of metabolic regulation in AAB and researches with its acetic acid resistance. PMID:28932219

  20. Improving Acetic Acid Production by Over-Expressing PQQ-ADH in Acetobacter pasteurianus.

    PubMed

    Wu, Xuefeng; Yao, Hongli; Cao, Lili; Zheng, Zhi; Chen, Xiaoju; Zhang, Min; Wei, Zhaojun; Cheng, Jieshun; Jiang, Shaotong; Pan, Lijun; Li, Xingjiang

    2017-01-01

    Pyrroquinoline quinone-dependent alcohol dehydrogenase (PQQ-ADH) is a key enzyme in the ethanol oxidase respiratory chain of acetic acid bacteria (AAB). To investigate the effect of PQQ-ADH on acetic acid production by Acetobacter pasteurianus JST-S, subunits I (adhA) and II (adhB) of PQQ-ADH were over-expressed, the fermentation parameters and the metabolic flux analysis were compared in the engineered strain and the original one. The acetic acid production was improved by the engineered strain (61.42 g L(-1)) while the residual ethanol content (4.18 g L(-1)) was decreased. Analysis of 2D maps indicated that 19 proteins were differently expressed between the two strains; of these, 17 were identified and analyzed by mass spectrometry and two-dimensional gel electrophoresis. With further investigation of metabolic flux analysis (MFA) of the pathway from ethanol and glucose, the results reveal that over-expression of PQQ-ADH is an effective way to improve the ethanol oxidation respiratory chain pathway and these can offer theoretical references for potential mechanism of metabolic regulation in AAB and researches with its acetic acid resistance.

  1. Proteins Induced during Adaptation of Acetobacter aceti to High Acetate Concentrations

    PubMed Central

    Steiner, Peter; Sauer, Uwe

    2001-01-01

    As a typical product of microbial metabolism, the weak acid acetate is well known for its cytotoxic effects. In contrast to most other microbes, the so-called acetic acid bacteria can acquire significant resistance to high acetate concentrations when properly adapted to such hostile conditions. To characterize the molecular events that are associated with this adaptation, we analyzed global protein expression levels during adaptation of Acetobacter aceti by two-dimensional gel electrophoresis. Adaptation was achieved by using serial batch and continuous cultivations with increasing acetate supplementation. Computer-aided analysis revealed a complex proteome response with at least 50 proteins that are specifically induced by adaptation to acetate but not by other stress conditions, such as heat or oxidative or osmotic stress. Of these proteins, 19 were significantly induced in serial batch and continuous cultures and were thus noted as acetate adaptation proteins (Aaps). Here we present first microsequence information on such Aaps from A. aceti. Membrane-associated processes appear to be of major importance for adaptation, because some of the Aap bear N-terminal sequence homology to membrane proteins and 11 of about 40 resolved proteins from membrane protein-enriched fractions are significantly induced. PMID:11722895

  2. Diversity of Acetobacter pasteurianus strains isolated from solid-state fermentation of cereal vinegars.

    PubMed

    Wu, JiaJia; Gullo, Maria; Chen, FuSheng; Giudici, Paolo

    2010-04-01

    Vinegar production is based on the acetification process by indigenous acetic acid bacteria (AAB). Among vinegar technologies, solid-state fermentation (SSF) processes are widespread in Asian countries to produce vinegar at small-scale. In this study, 21 AAB strains isolated from Chinese cereal vinegars produced by SSF collected in different regions of China were characterized by enterobacterial repetitive intergenic consensus (ERIC)-PCR fingerprinting. Isolates exhibited high degree of phenotypic variability as well as suitable traits for their uses as selected strains in SSF vinegar production (growth modality by superficial biofilm, no production of cellulose, ability to growth on ethanol media). 16S rRNA gene sequencing analysis of representative strains showed that strains of Acetobacter pasteurianus have a close association to cereal vinegars, whereas Gluconacetobacter europaeus population is not favoured. Selection of single or multiple strains culture within A. pasteurianus species was predicted in view of their application in SSF technology. This seems to be the first report showing phenotypic and genetic variability of AAB strains involved in SSF processes. Results can be exploited for the implementation of large-scale SSF processes by selected strains for vinegar production and other innovative biotechnological applications.

  3. Intramolecular electron transport in quinoprotein alcohol dehydrogenase of Acetobacter methanolicus: a redox-titration study

    PubMed

    Frébortova; Matsushita; Arata; Adachi

    1998-01-27

    Quinohemoprotein-cytochrome c complex alcohol dehydrogenase (ADH) of acetic acid bacteria consists of three subunits, of which subunit I contains pyrroloquinoline quinone (PQQ) and heme c, and subunit II contains three heme c components. The PQQ and heme c components are believed to be involved in the intramolecular electron transfer from ethanol to ubiquinone. To study the intramolecular electron transfer in ADH of Acetobacter methanolicus, the redox potentials of heme c components were determined with ADH complex and the isolated subunits I and II of A. methanolicus, as well as hybrid ADH consisting of the subunit I/III complex of Gluconobacter suboxydans ADH and subunit II of A. methanolicus ADH. The redox potentials of hemes c in ADH complex were -130, 49, 188, and 188 mV at pH 7.0 and 24, 187, 190, and 255 mV at pH 4.5. In hybrid ADH, one of these heme c components was largely changed in the redox potential. Reduced ADH was fully oxidized with potassium ferricyanide, while ubiquinone oxidized the enzyme partially. The results indicate that electrons extracted from ethanol at PQQ site are transferred to ubiquinone via heme c in subunit I and two of the three hemes c in subunit II. Copyright 1998 Elsevier Science B.V.

  4. Effect of ammonium and amino acids on the growth of selected strains of Gluconobacter and Acetobacter.

    PubMed

    Sainz, F; Mas, A; Torija, M J

    2017-02-02

    Acetic acid bacteria (AAB) are a group of microorganisms highly used in the food industry. However, its use can be limited by the insufficient information known about the nutritional requirements of AAB for optimal growth. The aim of this work was to study the effects of different concentrations and sources of nitrogen on the growth of selected AAB strains and to establish which nitrogen source best encouraged their growth. Two strains of three species of AAB, Gluconobacter japonicus, Gluconobacter oxydans and Acetobacter malorum, were grown in three different media with diverse nitrogen concentrations (25, 50, 100, and 300mgN/L and 1gN/L) as a complete solution of amino acids and ammonium. With this experiment, the most favourable medium and the lowest nitrogen concentration beneficial for the growth of each strain was selected. Subsequently, under these conditions, single amino acids or ammonium were added to media individually to determine the best nitrogen sources for each AAB strain. The results showed that nitrogen requirements are highly dependent on the nitrogen source, the medium and the AAB strain. Gluconobacter strains were able to grow in the lowest nitrogen concentration tested (25mgN/L); however, one of the G. oxydans strains and both A. malorum strains required a higher concentration of nitrogen (100-300mgN/L) for optimal growth. In general, single nitrogen sources were not able to support the growth of these AAB strains as well as the complete solution of amino acids and ammonium.

  5. Synthesizing speech

    NASA Astrophysics Data System (ADS)

    Siltanen, Samuli

    2015-01-01

    Samuli Siltanen explains how solving an "inverse problem" will improve the quality of life of people who can't speak and have to use voice synthesizers - particularly women and children, whose only current option is to sound like an adult male.

  6. Waveform synthesizer

    DOEpatents

    Franks, Larry A.; Nelson, Melvin A.

    1981-01-01

    A method of producing optical and electrical pulses of desired shape. An optical pulse of arbitrary but defined shape illuminates one end of an array of optical fiber waveguides of differing lengths to time differentiate the input pulse. The optical outputs at the other end of the array are combined to form a synthesized pulse of desired shape.

  7. Microbial cellulose--the natural power to heal wounds.

    PubMed

    Czaja, Wojciech; Krystynowicz, Alina; Bielecki, Stanislaw; Brown, R Malcolm

    2006-01-01

    Microbial cellulose (MC) synthesized in abundance by Acetobacter xylinum shows vast potential as a novel wound healing system. The high mechanical strength and remarkable physical properties result from the unique nanostructure of the never-dried membrane. This article attempts to briefly summarize the recent developments and applications of MC in the emerging field of novel wound dressings and skin substitutes. It considers the properties of the synthesized material, its clinical performance, as well as progress in the commercialization of MC for wound care products. Efficient and inexpensive fermentation techniques, not presently available, will be necessary to produce large quantities of the polymer.

  8. Characterization of a Major Cluster of nif, fix, and Associated Genes in a Sugarcane Endophyte, Acetobacter diazotrophicus

    PubMed Central

    Lee, Sunhee; Reth, Alexander; Meletzus, Dietmar; Sevilla, Myrna; Kennedy, Christina

    2000-01-01

    A major 30.5-kb cluster of nif and associated genes of Acetobacter diazotrophicus (syn. Gluconacetobacter diazotrophicus), a nitrogen-fixing endophyte of sugarcane, was sequenced and analyzed. This cluster represents the largest assembly of contiguous nif-fix and associated genes so far characterized in any diazotrophic bacterial species. Northern blots and promoter sequence analysis indicated that the genes are organized into eight transcriptional units. The overall arrangement of genes is most like that of the nif-fix cluster in Azospirillum brasilense, while the individual gene products are more similar to those in species of Rhizobiaceae or in Rhodobacter capsulatus. PMID:11092875

  9. Biocatalytic anti-Prelog reduction of prochiral ketones with whole cells of Acetobacter pasteurianus GIM1.158

    PubMed Central

    2014-01-01

    Background Enantiomerically pure alcohols are important building blocks for production of chiral pharmaceuticals, flavors, agrochemicals and functional materials and appropriate whole-cell biocatalysts offer a highly enantioselective, minimally polluting route to these valuable compounds. At present, most of these biocatalysts follow Prelog’s rule, and thus the (S)-alcohols are usually obtained when the smaller substituent of the ketone has the lower CIP priority. Only a few anti-Prelog (R)-specific whole cell biocatalysts have been reported. In this paper, the biocatalytic anti-Prelog reduction of 2-octanone to (R)-2-octanol was successfully conducted with high enantioselectivity using whole cells of Acetobacter pasteurianus GIM1.158. Results Compared with other microorganisms investigated, Acetobacter pasteurianus GIM1.158 was shown to be more effective for the reduction reaction, affording much higher yield, product enantiomeric excess (e.e.) and initial reaction rate. The optimal temperature, buffer pH, co-substrate and its concentration, substrate concentration, cell concentration and shaking rate were 35°C, 5.0, 500 mmol/L isopropanol, 40 mmol/L, 25 mg/mL and 120 r/min, respectively. Under the optimized conditions, the maximum yield and the product e.e. were 89.5% and >99.9%, respectively, in 70 minutes. Compared with the best available data in aqueous system (yield of 55%), the yield of (R)-2-octanol was greatly increased. Additionally, the efficient whole-cell biocatalytic process was feasible on a 200-mL preparative scale and the chemical yield increased to 95.0% with the product e.e. being >99.9%. Moreover, Acetobacter pasteurianus GIM1.158 cells were proved to be capable of catalyzing the anti-Prelog bioreduction of other prochiral carbonyl compounds with high efficiency. Conclusions Via an effective increase in the maximum yield and the product e.e. with Acetobacter pasteurianus GIM1.158 cells, these results open the way to use of whole cells of

  10. Cloning of genes responsible for acetic acid resistance in Acetobacter aceti.

    PubMed Central

    Fukaya, M; Takemura, H; Okumura, H; Kawamura, Y; Horinouchi, S; Beppu, T

    1990-01-01

    Five acetic acid-sensitive mutants of Acetobacter aceti subsp. aceti no. 1023 were isolated by mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. Three recombinant plasmids that complemented the mutations were isolated from a gene bank of the chromosome DNA of the parental strain constructed in Escherichia coli by using cosmid vector pMVC1. One of these plasmids (pAR1611), carrying about a 30-kilobase-pair (kb) fragment that conferred acetic acid resistance to all five mutants, was further analyzed. Subcloning experiments indicated that a 8.3-kb fragment was sufficient to complement all five mutations. To identify the mutation loci and genes involved in acetic acid resistance, insertional inactivation was performed by insertion of the kanamycin resistance gene derived from E. coli plasmid pACYC177 into the cloned 8.3-kb fragment and successive integration into the chromosome of the parental strain. The results suggested that three genes, designated aarA, aarB, and aarC, were responsible for expression of acetic acid resistance. Gene products of these genes were detected by means of overproduction in E. coli by use of the lac promoter. The amino acid sequence of the aarA gene product deduced from the nucleotide sequence was significantly similar to those of the citrate synthases (CSs) of E. coli and other bacteria. The A. aceti mutants defective in the aarA gene were found to lack CS activity, which was restored by introduction of a plasmid containing the aarA gene. A mutation in the CS gene of E. coli was also complemented by the aarA gene. These results indicate that aarA is the CS gene. Images FIG. 2 PMID:2156811

  11. Synthesizing Chaos

    NASA Astrophysics Data System (ADS)

    Blakely, Jonathan; Corron, Ned; Hayes, Scott; Pethel, Shawn

    2007-03-01

    Chaos is usually attributed only to nonlinear systems. Yet it was recently shown that chaotic waveforms can be synthesized by linear superposition of randomly polarized basis functions. The basis function contains a growing oscillation that terminates in a large pulse. We show that this function is easily realized when viewed backward in time as a pulse followed by ringing decay. Consequently, a linear filter driven by random pulses outputs a waveform that, when viewed backward in time, exhibits essential qualities of chaos, i.e. determinism and a positive Lyapunov exponent. This phenomenon suggests that chaos may be connected to physical theories whose framework is not that of a deterministic dynamical system. We demonstrate that synthesizing chaos requires a balance between the topological entropy of the random source and the dissipation in the filter. Surprisingly, using different encodings of the random source, the same filter can produce both Lorenz-like and R"ossler-like waveforms. The different encodings can be viewed as grammar restrictions on a more general encoding that produces a chaotic superset encompassing the Lorenz and R"ossler paradigms of nonlinear dynamics. Thus, the language of deterministic chaos provides a useful description for a class of signals not generated by a deterministic system.

  12. Effect of aspartic acid and glutamate on metabolism and acid stress resistance of Acetobacter pasteurianus.

    PubMed

    Yin, Haisong; Zhang, Renkuan; Xia, Menglei; Bai, Xiaolei; Mou, Jun; Zheng, Yu; Wang, Min

    2017-06-15

    Acetic acid bacteria (AAB) are widely applied in food, bioengineering and medicine fields. However, the acid stress at low pH conditions limits acetic acid fermentation efficiency and high concentration of vinegar production with AAB. Therefore, how to enhance resistance ability of the AAB remains as the major challenge. Amino acids play an important role in cell growth and cell survival under severe environment. However, until now the effects of amino acids on acetic fermentation and acid stress resistance of AAB have not been fully studied. In the present work the effects of amino acids on metabolism and acid stress resistance of Acetobacter pasteurianus were investigated. Cell growth, culturable cell counts, acetic acid production, acetic acid production rate and specific production rate of acetic acid of A. pasteurianus revealed an increase of 1.04, 5.43, 1.45, 3.30 and 0.79-folds by adding aspartic acid (Asp), and cell growth, culturable cell counts, acetic acid production and acetic acid production rate revealed an increase of 0.51, 0.72, 0.60 and 0.94-folds by adding glutamate (Glu), respectively. For a fully understanding of the biological mechanism, proteomic technology was carried out. The results showed that the strengthening mechanism mainly came from the following four aspects: (1) Enhancing the generation of pentose phosphates and NADPH for the synthesis of nucleic acid, fatty acids and glutathione (GSH) throughout pentose phosphate pathway. And GSH could protect bacteria from low pH, halide, oxidative stress and osmotic stress by maintaining the viability of cells through intracellular redox equilibrium; (2) Reinforcing deamination of amino acids to increase intracellular ammonia concentration to maintain stability of intracellular pH; (3) Enhancing nucleic acid synthesis and reparation of impaired DNA caused by acid stress damage; (4) Promoting unsaturated fatty acids synthesis and lipid transport, which resulted in the improvement of cytomembrane

  13. Effect of composites based nickel foam anode in microbial fuel cell using Acetobacter aceti and Gluconobacter roseus as a biocatalysts.

    PubMed

    Karthikeyan, Rengasamy; Krishnaraj, Navanietha; Selvam, Ammaiyappan; Wong, Jonathan Woon-Chung; Lee, Patrick K H; Leung, Michael K H; Berchmans, Sheela

    2016-10-01

    This study explores the use of materials such as chitosan (chit), polyaniline (PANI) and titanium carbide (TC) as anode materials for microbial fuel cells. Nickel foam (NF) was used as the base anode substrate. Four different types of anodes (NF, NF/PANI, NF/PANI/TC, NF/PANI/TC/Chit) are thus prepared and used in batch type microbial fuel cells operated with a mixed consortium of Acetobacter aceti and Gluconobacter roseus as the biocatalysts and bad wine as a feedstock. A maximum power density of 18.8Wm(-3) (≈2.3 times higher than NF) was obtained in the case of the anode modified with a composite of PANI/TC/Chit. The MFCs running under a constant external resistance of (50Ω) yielded 14.7% coulombic efficiency with a maximum chemical oxygen demand (COD) removal of 87-93%. The overall results suggest that the catalytic materials embedded in the chitosan matrix show the best performance and have potentials for further development.

  14. Global insights into acetic acid resistance mechanisms and genetic stability of Acetobacter pasteurianus strains by comparative genomics

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Shao, Yanchun; Chen, Tao; Chen, Wanping; Chen, Fusheng

    2015-12-01

    Acetobacter pasteurianus (Ap) CICC 20001 and CGMCC 1.41 are two acetic acid bacteria strains that, because of their strong abilities to produce and tolerate high concentrations of acetic acid, have been widely used to brew vinegar in China. To globally understand the fermentation characteristics, acid-tolerant mechanisms and genetic stabilities, their genomes were sequenced. Genomic comparisons with 9 other sequenced Ap strains revealed that their chromosomes were evolutionarily conserved, whereas the plasmids were unique compared with other Ap strains. Analysis of the acid-tolerant metabolic pathway at the genomic level indicated that the metabolism of some amino acids and the known mechanisms of acetic acid tolerance, might collaboratively contribute to acetic acid resistance in Ap strains. The balance of instability factors and stability factors in the genomes of Ap CICC 20001 and CGMCC 1.41 strains might be the basis for their genetic stability, consistent with their stable industrial performances. These observations provide important insights into the acid resistance mechanism and the genetic stability of Ap strains and lay a foundation for future genetic manipulation and engineering of these two strains.

  15. Involvement of Acetobacter orientalis in the production of lactobionic acid in Caucasian yogurt ("Caspian Sea yogurt") in Japan.

    PubMed

    Kiryu, T; Kiso, T; Nakano, H; Ooe, K; Kimura, T; Murakami, H

    2009-01-01

    Lactobionic acid was first found in a Caucasian fermented milk product popularly known as "Caspian Sea yogurt" in Japan. The presence of lactobionic acid in the fermented milk was indicated by the results of both high-performance anion-exchange chromatographic analysis with pulsed amperometric detection and mass spectrometric analysis. Thereafter, the acid was purified from the yogurt and analyzed by nuclear magnetic resonance. A substantial amount of lactobionic acid was found to be accumulated in the upper layer of the yogurt, especially within 10 mm from the surface. A total of 45 mg of lactobionic acid per 100 g of the upper yogurt layer was collected after 4 d of fermentation. The annual intake of lactobionic acid in individuals consuming 100 g of the yogurt every day would be 0.5 to 1.0 g. A lactose-oxidizing bacterium was isolated from the fermented milk and was identified as Acetobacter orientalis. Washed A. orientalis cells oxidized monosaccharides such as d-glucose at considerable rates, although their activities for substrates such as lactose, maltose, and cellobiose were much lower. When A. orientalis cells were cultivated in cow's milk, they exhibited lactose-oxidizing activity, suggesting that this bacterium was the main organism involved in the production of lactobionic acid in the yogurt.

  16. Global insights into acetic acid resistance mechanisms and genetic stability of Acetobacter pasteurianus strains by comparative genomics.

    PubMed

    Wang, Bin; Shao, Yanchun; Chen, Tao; Chen, Wanping; Chen, Fusheng

    2015-12-22

    Acetobacter pasteurianus (Ap) CICC 20001 and CGMCC 1.41 are two acetic acid bacteria strains that, because of their strong abilities to produce and tolerate high concentrations of acetic acid, have been widely used to brew vinegar in China. To globally understand the fermentation characteristics, acid-tolerant mechanisms and genetic stabilities, their genomes were sequenced. Genomic comparisons with 9 other sequenced Ap strains revealed that their chromosomes were evolutionarily conserved, whereas the plasmids were unique compared with other Ap strains. Analysis of the acid-tolerant metabolic pathway at the genomic level indicated that the metabolism of some amino acids and the known mechanisms of acetic acid tolerance, might collaboratively contribute to acetic acid resistance in Ap strains. The balance of instability factors and stability factors in the genomes of Ap CICC 20001 and CGMCC 1.41 strains might be the basis for their genetic stability, consistent with their stable industrial performances. These observations provide important insights into the acid resistance mechanism and the genetic stability of Ap strains and lay a foundation for future genetic manipulation and engineering of these two strains.

  17. Simultaneous degradation of bad wine and electricity generation with the aid of the coexisting biocatalysts Acetobacter aceti and Gluconobacter roseus.

    PubMed

    Rengasamy, Karthikeyan; Berchmans, Sheela

    2012-01-01

    This study describes the cooperative effect of the two biocatalysts Acetobacter aceti and Gluconobacter roseus for biodegradation as well as current generation. The electro activity of the biofilms of these two microorganisms was investigated by the bioelectrocatalytic oxidation of ethanol and glucose using cyclic voltammetry. Two chamber microbial fuel cells (MFCs) were constructed using single culture of A. aceti (A-MFC), and G. roseus (G-MFC) and also using mixed culture (AG-MFC). Each MFC was fed with four different substrates viz., glucose, ethanol, acetate and bad wine. AG-MFC produced higher power density with glucose (1.05 W/m(3)), ethanol (1.97 W/m(3)), acetate (1.39 W/m(3)) and bad wine (3.82 W/m(3)). COD removal (94%) was maximum for acetate fed MFCs. Higher coulombic efficiency was obtained with bad wine (45%) as the fuel. This work provides the scope of using these biofuel cells in wineries for performing the dual duty of bad wine degradation along with current generation.

  18. Global insights into acetic acid resistance mechanisms and genetic stability of Acetobacter pasteurianus strains by comparative genomics

    PubMed Central

    Wang, Bin; Shao, Yanchun; Chen, Tao; Chen, Wanping; Chen, Fusheng

    2015-01-01

    Acetobacter pasteurianus (Ap) CICC 20001 and CGMCC 1.41 are two acetic acid bacteria strains that, because of their strong abilities to produce and tolerate high concentrations of acetic acid, have been widely used to brew vinegar in China. To globally understand the fermentation characteristics, acid-tolerant mechanisms and genetic stabilities, their genomes were sequenced. Genomic comparisons with 9 other sequenced Ap strains revealed that their chromosomes were evolutionarily conserved, whereas the plasmids were unique compared with other Ap strains. Analysis of the acid-tolerant metabolic pathway at the genomic level indicated that the metabolism of some amino acids and the known mechanisms of acetic acid tolerance, might collaboratively contribute to acetic acid resistance in Ap strains. The balance of instability factors and stability factors in the genomes of Ap CICC 20001 and CGMCC 1.41 strains might be the basis for their genetic stability, consistent with their stable industrial performances. These observations provide important insights into the acid resistance mechanism and the genetic stability of Ap strains and lay a foundation for future genetic manipulation and engineering of these two strains. PMID:26691589

  19. Green synthesis of bacterial cellulose via acetic acid pre-hydrolysis liquor of agricultural corn stalk used as carbon source.

    PubMed

    Cheng, Zheng; Yang, Rendang; Liu, Xu; Liu, Xiao; Chen, Hua

    2017-06-01

    Herein, bacterial cellulose (BC) was synthesized by acetobacter xylinum via organic acid pre-hydrolysis liquor of agricultural corn stalk used as carbon source. Acetic acid was applied to pretreat the corn stalk, then, the prehydrolysate was detoxified by sequential steps of activated carbon and ion exchange resin treatment prior to use as carbon source to cultivate acetobacter xylinum. Moreover, the recovery of acetic acid was achieved for facilitating the reduction of cost. The results revealed that the combination method of detoxification treatment was very effective for synthesis of BC, yield could be up to 2.86g/L. SEM analysis showed that the diameter size of BC between 20 and 70mm. In summary, the process that bacterial cellulose was biosynthesized via prehydrolysate from agricultural corn stalk used as carbon source is feasible, and the ability to recover organic acid make it economical, sustainable and green, which fits well into the biorefinery concept. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. The effect of sulphur dioxide and oxygen on the viability and culturability of a strain of Acetobacter pasteurianus and a strain of Brettanomyces bruxellensis isolated from wine.

    PubMed

    du Toit, W J; Pretorius, I S; Lonvaud-Funel, A

    2005-01-01

    The objective of this study was to investigate the effects of free molecular and bound forms of sulphur dioxide and oxygen on the viability and culturability of a selected strain of Acetobacter pasteurianus and a selected strain of Brettanomyces bruxellensis in wine. Acetic acid bacteria and Brettanomyces/Dekkera yeasts associated with wine spoilage were isolated from bottled commercial red wines. One bacterium, A. pasteurianus strain A8, and one yeast, B. bruxellensis strain B3a, were selected for further study. The resistance to sulphur dioxide and the effect of oxygen addition on these two selected strains were determined by using plating and epifluorescence techniques for monitoring cell viability in wine. Acetobacter pasteurianus A8 was more resistant to sulphur dioxide than B. bruxellensis B3a, with the latter being rapidly affected by a short exposure time to free molecular form of sulphur dioxide. As expected, neither of these microbial strains was affected by the bound form of sulphur dioxide. The addition of oxygen negated the difference observed between plate and epifluorescence counts for A. pasteurianus A8 during storage, while it stimulated growth of B. bruxellensis B3a. Acetobacter pasteurianus A8 can survive under anaerobic conditions in wine in the presence of sulphur dioxide. Brettanomyces bruxellensis B3a is more sensitive to sulphur dioxide than A. pasteurianus A8, but can grow in the presence of oxygen. Care should be taken to exclude oxygen from contact with wine when it is being transferred or moved. Wine spoilage can be avoided by preventing growth of undesirable acetic acid bacteria and Brettanomyces/Dekkera yeasts through the effective use of sulphur dioxide and the management of oxygen throughout the winemaking process.

  1. Simultaneous production of acetic and gluconic acids by a thermotolerant Acetobacter strain during acetous fermentation in a bioreactor.

    PubMed

    Mounir, Majid; Shafiei, Rasoul; Zarmehrkhorshid, Raziyeh; Hamouda, Allal; Ismaili Alaoui, Mustapha; Thonart, Philippe

    2016-02-01

    The activity of bacterial strains significantly influences the quality and the taste of vinegar. Previous studies of acetic acid bacteria have primarily focused on the ability of bacterial strains to produce high amounts of acetic acid. However, few studies have examined the production of gluconic acid during acetous fermentation at high temperatures. The production of vinegar at high temperatures by two strains of acetic acid bacteria isolated from apple and cactus fruits, namely AF01 and CV01, respectively, was evaluated in this study. The simultaneous production of gluconic and acetic acids was also examined in this study. Biochemical and molecular identification based on a 16s rDNA sequence analysis confirmed that these strains can be classified as Acetobacter pasteurianus. To assess the ability of the isolated strains to grow and produce acetic acid and gluconic acid at high temperatures, a semi-continuous fermentation was performed in a 20-L bioreactor. The two strains abundantly grew at a high temperature (41°C). At the end of the fermentation, the AF01 and CV01 strains yielded acetic acid concentrations of 7.64% (w/v) and 10.08% (w/v), respectively. Interestingly, CV01 was able to simultaneously produce acetic and gluconic acids during acetic fermentation, whereas AF01 mainly produced acetic acid. In addition, CV01 was less sensitive to ethanol depletion during semi-continuous fermentation. Finally, the enzymatic study showed that the two strains exhibited high ADH and ALDH enzyme activity at 38°C compared with the mesophilic reference strain LMG 1632, which was significantly susceptible to thermal inactivation. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  2. A Novel Carbonyl Reductase with Anti-Prelog Stereospecificity from Acetobacter sp. CCTCC M209061: Purification and Characterization

    PubMed Central

    Wang, Xiao-Ting; Zong, Min-Hua; Lou, Wen-Yong

    2014-01-01

    A novel carbonyl reductase (AcCR) catalyzing the asymmetric reduction of ketones to enantiopure alcohols with anti-Prelog stereoselectivity was found in Acetobacter sp. CCTCC M209061 and enriched 27.5-fold with an overall yield of 0.4% by purification. The enzyme showed a homotetrameric structure with an apparent molecular mass of 104 kDa and each subunit of 27 kDa. The gene sequence of AcCR was cloned and sequenced, and a 762 bp gene fragment was obtained. Either NAD(H) or NADP(H) can be used as coenzyme. For the reduction of 4′-chloroacetophenone, the Km value for NADH was around 25-fold greater than that for NADPH (0.66 mM vs 0.026 mM), showing that AcCR preferred NADPH over NADH. However, when NADH was used as cofactor, the response of AcCR activity to increasing concentration of 4′-chloroacetophenone was clearly sigmoidal with a Hill coefficient of 3.1, suggesting that the enzyme might possess four substrate-binding sites cooperating with each other The Vmax value for NADH-linked reduction was higher than that for NADPH-linked reduction (0.21 mM/min vs 0.17 mM/min). For the oxidation of isopropanol, the similar enzymological properties of AcCR were found using NAD+ or NADP+ as cofactor. Furthermore, a broad range of ketones such as aryl ketones, α-ketoesters and aliphatic ketones could be enantioselectively reduced into the corresponding chiral alcohols by this enzyme with high activity. PMID:24740089

  3. Influence of carbon sources on the viability and resuscitation of Acetobacter senegalensis during high-temperature gluconic acid fermentation.

    PubMed

    Shafiei, Rasoul; Zarmehrkhorshid, Raziyeh; Mounir, Majid; Thonart, Philippe; Delvigne, Frank

    2017-02-15

    Much research has been conducted about different types of fermentation at high temperature, but only a few of them have studied cell viability changes during high-temperature fermentation. In this study, Acetobacter senegalensis, a thermo-tolerant strain, was used for gluconic acid production at 38 °C. The influences of different carbon sources and physicochemical conditions on cell viability and the resuscitation of viable but nonculturable (VBNC) cells formed during fermentation were studied. Based on the obtained results, A. senegalensis could oxidize 95 g l(- 1) glucose to gluconate at 38 °C (pH 5.5, yield 83%). However, despite the availability of carbon and nitrogen sources, the specific rates of glucose consumption (qs) and gluconate production (qp) reduced progressively. Interestingly, gradual qs and qp reduction coincided with gradual decrease in cellular dehydrogenase activity, cell envelope integrity, and cell culturability as well as with the formation of VBNC cells. Entry of cells into VBNC state during stationary phase partly stemmed from high fermentation temperature and long-term oxidation of glucose, because just about 48% of VBNC cells formed during stationary phase were resuscitated by supplementing the culture medium with an alternative favorite carbon source (low concentration of ethanol) and/or reducing incubation temperature to 30 °C. This indicates that ethanol, as a favorable carbon source, supports the repair of stressed cells. Since formation of VBNC cells is often inevitable during high-temperature fermentation, using an alternative carbon source together with changing physicochemical conditions may enable the resuscitation of VBNC cells and their use for several production cycles.

  4. Influence of glycerol on production and structural-physical properties of cellulose from Acetobacter sp. V6 cultured in shake flasks.

    PubMed

    Jung, Ho-Il; Jeong, Jin-Ha; Lee, O-Mi; Park, Geun-Tae; Kim, Keun-Ki; Park, Hyean-Cheal; Lee, Sang-Mong; Kim, Young-Gyun; Son, Hong-Joo

    2010-05-01

    Cost-effective production of bacterial cellulose (BC) by Acetobacter sp. V6 was investigated in shake culture using glycerol as carbon source and its structural and physical properties were determined. In medium containing 3% (w/v) glycerol, BC production was 4.98+/-0.03g/l after 7 days. This value was 3.8-fold higher than the yield in the glucose medium. FT-IR spectra revealed that all the BC samples were highly crystalline and were cellulose type capital I, Ukrainian. The crystallinity index value of the BC produced was 9% higher in the glycerol medium than in the glucose medium. Scanning electron micrographs showed that BC from the glycerol medium was more compact than that from the glucose medium. Water-holding capacity and viscosity of BC from the glycerol medium had 61.3% and 22.4% lower values than those from the glucose medium. These results suggest that glycerol could be a potential low-cost substrate for BC production by Acetobacter sp. V6, leading to the reduction in the production cost.

  5. Portable Speech Synthesizer

    NASA Technical Reports Server (NTRS)

    Leibfritz, Gilbert H.; Larson, Howard K.

    1987-01-01

    Compact speech synthesizer useful traveling companion to speech-handicapped. User simply enters statement on board, and synthesizer converts statement into spoken words. Battery-powered and housed in briefcase, easily carried on trips. Unit used on telephones and face-to-face communication. Synthesizer consists of micro-computer with memory-expansion module, speech-synthesizer circuit, batteries, recharger, dc-to-dc converter, and telephone amplifier. Components, commercially available, fit neatly in 17-by 13-by 5-in. briefcase. Weighs about 20 lb (9 kg) and operates and recharges from ac receptable.

  6. Cloning and functional analysis of adhS gene encoding quinoprotein alcohol dehydrogenase subunit III from Acetobacter pasteurianus SKU1108.

    PubMed

    Masud, Uraiwan; Matsushita, Kazunobu; Theeragool, Gunjana

    2010-03-31

    The adhS gene which encodes the smallest subunit, subunit III, of quinoprotein alcohol dehydrogenase (PQQ-ADH) from Acetobacter pasteurianus SKU1108 has been cloned and characterized. The role of this subunit on the function of PQQ-ADH was investigated by construction of adhS gene disruptant and mutants. The adhS gene disruptant completely lost its PQQ-ADH activity and acetate-producing ability but retained acetic acid toleration. In contrast, this disruptant grew well, even better than the wild type, in the ethanol containing medium even though its PQQ-ADH activity and ethanol oxidizing ability was completely lost, while NAD(+)-dependent ADH (NAD(+)-ADH) was induced. Heme staining and immunoblot analysis of both membrane and soluble fractions with anti-ADH subunit III suggested that ethanol did not affect the adhS gene expression but induced PQQ-ADH activity. Over-expressed adhS did not enhance acetic acid production in both the wild type and the adhS disruptant. In addition, deletion analysis of upstream region of adhS gene suggested that its tentative promoter(s) might be located at around 118-268 bp upstream from an initiation codon. Random mutagenesis of adhS gene revealed that complete loss of PQQ-ADH activity and ethanol oxidizing ability were observed in the mutants' lack of the 140 and 73 amino acid residues at the C-terminal, whereas the lack of 22 amino acid residues at the C-terminal affected neither the PQQ-ADH activity nor ethanol oxidizing ability. In addition, some amino acid substitutions such as Leu18Gln, Ala26Val, Val36Ile, Val54Ile, Gly55Asp, Val70Ala and Val107Ala did not show any affect on PQQ-ADH activity and ethanol oxidizing ability. Interestingly, alteration of Thr104Lys led to a complete loss of ethanol oxidizing ability. However, point mutation at the possible promoter region also exhibited low PQQ-ADH activity and ethanol oxidizing ability. This result suggests that 104Thr might be involved in molecular coupling with subunit I in order

  7. Markedly improving asymmetric oxidation of 1-(4-methoxyphenyl) ethanol with Acetobacter sp. CCTCC M209061 cells by adding deep eutectic solvent in a two-phase system.

    PubMed

    Wei, Ping; Liang, Jing; Cheng, Jing; Zong, Min-Hua; Lou, Wen-Yong

    2016-01-13

    Enantiopure (S)-1-(4-methoxyphenyl) ethanol {(S)-MOPE} can be employed as an important synthon for the synthesis of cycloalkyl [b] indoles with the treatment function for general allergic response. To date, the biocatalytic resolution of racemic MOPE through asymmetric oxidation in the biphasic system has remained largely unexplored. Additionally, deep eutectic solvents (DESs), as a new class of promising green solvents, have recently gained increasing attention in biocatalysis for their excellent properties and many successful examples in biocatalytic processes. In this study, the biocatalytic asymmetric oxidation of MOPE to get (S)-MOPE using Acetobacter sp. CCTCC M209061 cells was investigated in different two-phase systems, and adding DES in a biphasic system was also explored to further improve the reaction efficiency of the biocatalytic oxidation. Of all the examined water-immiscible organic solvents and ionic liquids (ILs), 1-butyl-3-methylimidazolium hexafluorophoshpate ([C4MIM][PF6]) afforded the best results, and consequently was selected as the second phase of a two-phase system for the asymmetric oxidation of MOPE with immobilized Acetobacter sp. CCTCC M209061 cells. For the reaction performed in the [C4MIM][PF6]/buffer biphasic system, under the optimized conditions, the initial reaction rate, the maximum conversion and the residual substrate e.e. recorded 97.8 μmol/min, 50.5 and >99.9 % after 10 h reaction. Furthermore, adding the DES [ChCl][Gly] (10 %, v/v) to the aqueous phase, the efficiency of the biocatalytic oxidation was rose markedly. The optimal substrate concentration and the initial reaction rate were significantly increased to 80 mmol/L and 124.0 μmol/min, respectively, and the reaction time was shortened to 7 h with 51.3 % conversion. The immobilized cell still retained over 72 % of its initial activity after 9 batches of successive reuse in the [C4MIM][PF6]/[ChCl][Gly]-containing buffer system. Additionally, the efficient biocatalytic

  8. Multiplexed chirp waveform synthesizer

    DOEpatents

    Dudley, Peter A.; Tise, Bert L.

    2003-09-02

    A synthesizer for generating a desired chirp signal has M parallel channels, where M is an integer greater than 1, each channel including a chirp waveform synthesizer generating at an output a portion of a digital representation of the desired chirp signal; and a multiplexer for multiplexing the M outputs to create a digital representation of the desired chirp signal. Preferably, each channel receives input information that is a function of information representing the desired chirp signal.

  9. Optimization of culture conditions to produce high yields of active Acetobacter sp. CCTCC M209061 cells for anti-Prelog reduction of prochiral ketones

    PubMed Central

    2011-01-01

    Background Chiral alcohols are widely used in the synthesis of chiral pharmaceuticals, flavors and functional materials and appropriate whole-cell biocatalysts offer a highly enantioselective, minimally polluting route to these valuable compounds. The recently isolated strain Acetobacter sp. CCTCC M209061 showed exclusive anti-Prelog stereoselectivity for the reduction of prochiral ketones, but the low biomass has limited its commercialization and industrial applications. To tackle this problem, the effects of medium components and culture conditions on the strain's growth and reduction activity were explored. Results By using a one-at-a-time method and a central composite rotatable design (CCRD), the optimal medium and culture conditions were found to be as follows: glucose 8.26 g/L, fructose 2.50 g/L, soy peptone 83.92 g/L, MnSO4·H2O 0.088 g/L, pH 5.70, 30°C and 10% (v/v) inoculum. Under the above-mentioned conditions, the biomass after 30 h cultivation reached 1.10 ± 0.03 g/L, which was 9.5-fold higher than that obtained with basic medium. Also, the reduction activity towards 4'-chloroacetophenone was markedly enhanced to 39.49 ± 0.96 μmol/min/g from 29.34 ± 0.65 μmol/min/g, with the product e.e. being above 99%. Comparable improvements were also seen with the enantioselective bioreduction of 4-(trimethylsilyl)-3-butyn-2-one to the key pharmaceutical precursor (R) - 4-(trimethylsilyl)-3-butyn-2-ol. Conclusions The biomass and reduction activity of Acetobacter sp. CCTCC M209061 can be greatly enhanced through the optimization strategy. This facilitates use of the strain in the anti-Prelog stereoselective reduction of prochiral ketones to enantiopure chiral alcohols as building blocks for many industries. PMID:22099947

  10. PULSE SYNTHESIZING GENERATOR

    DOEpatents

    Kerns, Q.A.

    1963-08-01

    >An electronlc circuit for synthesizing electrical current pulses having very fast rise times includes several sinewave generators tuned to progressively higher harmonic frequencies with signal amplitudes and phases selectable according to the Fourier series of the waveform that is to be synthesized. Phase control is provided by periodically triggering the generators at precisely controlled times. The outputs of the generators are combined in a coaxial transmission line. Any frequency-dependent delays that occur in the transmission line can be readily compensated for so that the desired signal wave shape is obtained at the output of the line. (AEC)

  11. Wisdom, Intelligence & Creativity Synthesized

    ERIC Educational Resources Information Center

    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…

  12. Wisdom, Intelligence & Creativity Synthesized

    ERIC Educational Resources Information Center

    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…

  13. The Journal Synthesizing Activity.

    ERIC Educational Resources Information Center

    Garber, Zev

    The journal synthesizing activity is intended to combine aspects of the formal essay with that of a diary. Activities associated with lecture topics are written up as short journal entries of approximately five typewritten pages and are turned in during the weekly class session at which the related topic is being discussed. The journal project…

  14. Synthesized night vision goggle

    NASA Astrophysics Data System (ADS)

    Zhou, Haixian

    2000-06-01

    A Synthesized Night Vision Goggle that will be described int his paper is a new type of night vision goggle with multiple functions. It consists of three parts: main observing system, picture--superimposed system (or Cathode Ray Tube system) and Charge-Coupled Device system.

  15. Fermentation of a bacterial cellulose/xylan composite by mixed ruminal microflora: implications for the role of polysaccharide matrix interactions in plant cell wall biodegradability.

    PubMed

    Weimer, P J; Hackney, J M; Jung, H J; Hatfield, R D

    2000-05-01

    Growth of the cellulose-synthesizing bacterium Acetobacter xylinum ATCC 53524 in media supplemented with 5% (w/v) glucose and 0.2% (w/v) of a water-soluble, nearly linear xylan from tobacco stalks resulted in the synthesis of a highly crystalline composite having a xylose/glucose ratio ranging from 0.06 to 0.24. The digestion of one composite (88% cellulose/12% xylan) by mixed ruminal microflora displayed kinetics of gas production similar to those of an unassociated mixture of the two components added in a xylan/cellulose ratio similar to that of the composite. The data suggest that intimate association of xylan and cellulose, as is typically found in secondary plant cell walls, does not inhibit the rate of digestion of the component polysaccharides.

  16. Explaining Synthesized Software

    NASA Technical Reports Server (NTRS)

    VanBaalen, Jeffrey; Robinson, Peter; Lowry, Michael; Pressburger, Thomas; Lau, Sonie (Technical Monitor)

    1998-01-01

    Motivated by NASA's need for high-assurance software, NASA Ames' Amphion project has developed a generic program generation system based on deductive synthesis. Amphion has a number of advantages, such as the ability to develop a new synthesis system simply by writing a declarative domain theory. However, as a practical matter, the validation of the domain theory for such a system is problematic because the link between generated programs and the domain theory is complex. As a result, when generated programs do not behave as expected, it is difficult to isolate the cause, whether it be an incorrect problem specification or an error in the domain theory. This paper describes a tool we are developing that provides formal traceability between specifications and generated code for deductive synthesis systems. It is based on extensive instrumentation of the refutation-based theorem prover used to synthesize programs. It takes augmented proof structures and abstracts them to provide explanations of the relation between a specification, a domain theory, and synthesized code. In generating these explanations, the tool exploits the structure of Amphion domain theories, so the end user is not confronted with the intricacies of raw proof traces. This tool is crucial for the validation of domain theories as well as being important in everyday use of the code synthesis system. It plays an important role in validation because when generated programs exhibit incorrect behavior, it provides the links that can be traced to identify errors in specifications or domain theory. It plays an important role in the everyday use of the synthesis system by explaining to users what parts of a specification or of the domain theory contribute to what pieces of a generated program. Comments are inserted into the synthesized code that document these explanations.

  17. Synthesizing folded band chaos

    NASA Astrophysics Data System (ADS)

    Corron, Ned J.; Hayes, Scott T.; Pethel, Shawn D.; Blakely, Jonathan N.

    2007-04-01

    A randomly driven linear filter that synthesizes Lorenz-like, reverse-time chaos is shown also to produce Rössler-like folded band wave forms when driven using a different encoding of the random source. The relationship between the topological entropy of the random source, dissipation in the linear filter, and the positive Lyapunov exponent for the reverse-time wave form is exposed. The two drive encodings are viewed as grammar restrictions on a more general encoding that produces a chaotic superset encompassing both the Lorenz butterfly and Rössler folded band paradigms of nonlinear dynamics.

  18. Formyl-coenzyme A (CoA):oxalate CoA-transferase from the acidophile Acetobacter aceti has a distinctive electrostatic surface and inherent acid stability

    PubMed Central

    Mullins, Elwood A; Starks, Courtney M; Francois, Julie A; Sael, Lee; Kihara, Daisuke; Kappock, T Joseph

    2012-01-01

    Bacterial formyl-CoA:oxalate CoA-transferase (FCOCT) and oxalyl-CoA decarboxylase work in tandem to perform a proton-consuming decarboxylation that has been suggested to have a role in generalized acid resistance. FCOCT is the product of uctB in the acidophilic acetic acid bacterium Acetobacter aceti. As expected for an acid-resistance factor, UctB remains folded at the low pH values encountered in the A. aceti cytoplasm. A comparison of crystal structures of FCOCTs and related proteins revealed few features in UctB that would distinguish it from nonacidophilic proteins and thereby account for its acid stability properties, other than a strikingly featureless electrostatic surface. The apparently neutral surface is a result of a “speckled” charge decoration, in which charged surface residues are surrounded by compensating charges but do not form salt bridges. A quantitative comparison among orthologs identified a pattern of residue substitution in UctB that may be a consequence of selection for protein stability by constant exposure to acetic acid. We suggest that this surface charge pattern, which is a distinctive feature of A. aceti proteins, creates a stabilizing electrostatic network without stiffening the protein or compromising protein–solvent interactions. PMID:22374910

  19. Combination of deep eutectic solvent and ionic liquid to improve biocatalytic reduction of 2-octanone with Acetobacter pasteurianus GIM1.158 cell

    PubMed Central

    Xu, Pei; Du, Peng-Xuan; Zong, Min-Hua; Li, Ning; Lou, Wen-Yong

    2016-01-01

    The efficient anti-Prelog asymmetric reduction of 2-octanone with Acetobacter pasteurianus GIM1.158 cells was successfully performed in a biphasic system consisting of deep eutectic solvent (DES) and water-immiscible ionic liquid (IL). Various DESs exerted different effects on the synthesis of (R)-2-octanol. Choline chloride/ethylene glycol (ChCl/EG) exhibited good biocompatibility and could moderately increase the cell membrane permeability thus leading to the better results. Adding ChCl/EG increased the optimal substrate concentration from 40 mM to 60 mM and the product e.e. kept above 99.9%. To further improve the reaction efficiency, water-immiscible ILs were introduced to the reaction system and an enhanced substrate concentration (1.5 M) was observed with C4MIM·PF6. Additionally, the cells manifested good operational stability in the reaction system. Thus, the efficient biocatalytic process with ChCl/EG and C4MIM·PF6 was promising for efficient synthesis of (R)-2-octanol. PMID:27185089

  20. Combination of deep eutectic solvent and ionic liquid to improve biocatalytic reduction of 2-octanone with Acetobacter pasteurianus GIM1.158 cell

    NASA Astrophysics Data System (ADS)

    Xu, Pei; Du, Peng-Xuan; Zong, Min-Hua; Li, Ning; Lou, Wen-Yong

    2016-05-01

    The efficient anti-Prelog asymmetric reduction of 2-octanone with Acetobacter pasteurianus GIM1.158 cells was successfully performed in a biphasic system consisting of deep eutectic solvent (DES) and water-immiscible ionic liquid (IL). Various DESs exerted different effects on the synthesis of (R)-2-octanol. Choline chloride/ethylene glycol (ChCl/EG) exhibited good biocompatibility and could moderately increase the cell membrane permeability thus leading to the better results. Adding ChCl/EG increased the optimal substrate concentration from 40 mM to 60 mM and the product e.e. kept above 99.9%. To further improve the reaction efficiency, water-immiscible ILs were introduced to the reaction system and an enhanced substrate concentration (1.5 M) was observed with C4MIM·PF6. Additionally, the cells manifested good operational stability in the reaction system. Thus, the efficient biocatalytic process with ChCl/EG and C4MIM·PF6 was promising for efficient synthesis of (R)-2-octanol.

  1. SYNTH: A spectrum synthesizer

    NASA Astrophysics Data System (ADS)

    Hensley, W. K.; McKinnon, A. D.; Miley, H. S.; Panisko, M. E.; Savard, R. M.

    1993-10-01

    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.

  2. Programmable electronic synthesized capacitance

    NASA Technical Reports Server (NTRS)

    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.

  3. Method for synthesizing HMX

    DOEpatents

    McGuire, Raymond R.; Coon, Clifford L.; Harrar, Jackson E.; Pearson, Richard K.

    1984-01-01

    A method and apparatus for electrochemically synthesizing N.sub.2 O.sub.5 cludes oxidizing a solution of N.sub.2 O.sub.4 /HNO.sub.3 at an anode, while maintaining a controlled potential between the N.sub.2 O.sub.4 /HNO.sub.3 solution and the anode. A potential of about 1.35 to 2.0 V vs. SCE is preferred, while a potential of about 1.80 V vs. SCE is most preferred. Thereafter, the N.sub.2 O.sub.5 is reacted with either 1.5-diacetyl-3,7-dinitro-1,3,5,7-tetraazacyclooctane (DADN) or 1,3,5,7-tetraacetyl-1,3,5,7-tetraazacyclooctane (TAT) to form cyclotetramethylenetetraamine (HMX).

  4. Synthesized light transients.

    PubMed

    Wirth, A; Hassan, M Th; Grguras, I; Gagnon, J; Moulet, A; Luu, T T; Pabst, S; Santra, R; Alahmed, Z A; Azzeer, A M; Yakovlev, V S; Pervak, V; Krausz, F; Goulielmakis, E

    2011-10-14

    Manipulation of electron dynamics calls for electromagnetic forces that can be confined to and controlled over sub-femtosecond time intervals. Tailored transients of light fields can provide these forces. We report on the generation of subcycle field transients spanning the infrared, visible, and ultraviolet frequency regimes with a 1.5-octave three-channel optical field synthesizer and their attosecond sampling. To demonstrate applicability, we field-ionized krypton atoms within a single wave crest and launched a valence-shell electron wavepacket with a well-defined initial phase. Half-cycle field excitation and attosecond probing revealed fine details of atomic-scale electron motion, such as the instantaneous rate of tunneling, the initial charge distribution of a valence-shell wavepacket, the attosecond dynamic shift (instantaneous ac Stark shift) of its energy levels, and its few-femtosecond coherent oscillations.

  5. Doclet To Synthesize UML

    NASA Technical Reports Server (NTRS)

    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.

  6. Preliminary Study on Biosynthesis of Bacterial Nanocellulose Tubes in a Novel Double-Silicone-Tube Bioreactor for Potential Vascular Prosthesis.

    PubMed

    Hong, Feng; Wei, Bin; Chen, Lin

    2015-01-01

    Bacterial nanocellulose (BNC) has demonstrated a tempting prospect for applications in substitute of small blood vessels. However, present technology is inefficient in production and BNC tubes have a layered structure that may bring danger after implanting. Double oxygen-permeable silicone tubes in different diameters were therefore used as a tube-shape mold and also as oxygenated supports to construct a novel bioreactor for production of the tubular BNC materials. Double cannula technology was used to produce tubular BNC via cultivations with Acetobacter xylinum, and Kombucha, a symbiosis of acetic acid bacteria and yeasts. The results indicated that Kombucha gave higher yield and productivity of BNC than A. xylinum. Bacterial nanocellulose was simultaneously synthesized both on the inner surface of the outer silicone tube and on the outer surface of the inner silicone tube. Finally, the nano BNC fibrils from two directions formed a BNC tube with good structural integrity. Scanning electron microscopy inspection showed that the tubular BNC had a multilayer structure in the beginning but finally it disappeared and an intact BNC tube formed. The mechanical properties of BNC tubes were comparable with the reported value in literatures, demonstrating a great potential in vascular implants or in functional substitutes in biomedicine.

  7. Preliminary Study on Biosynthesis of Bacterial Nanocellulose Tubes in a Novel Double-Silicone-Tube Bioreactor for Potential Vascular Prosthesis

    PubMed Central

    Wei, Bin; Chen, Lin

    2015-01-01

    Bacterial nanocellulose (BNC) has demonstrated a tempting prospect for applications in substitute of small blood vessels. However, present technology is inefficient in production and BNC tubes have a layered structure that may bring danger after implanting. Double oxygen-permeable silicone tubes in different diameters were therefore used as a tube-shape mold and also as oxygenated supports to construct a novel bioreactor for production of the tubular BNC materials. Double cannula technology was used to produce tubular BNC via cultivations with Acetobacter xylinum, and Kombucha, a symbiosis of acetic acid bacteria and yeasts. The results indicated that Kombucha gave higher yield and productivity of BNC than A. xylinum. Bacterial nanocellulose was simultaneously synthesized both on the inner surface of the outer silicone tube and on the outer surface of the inner silicone tube. Finally, the nano BNC fibrils from two directions formed a BNC tube with good structural integrity. Scanning electron microscopy inspection showed that the tubular BNC had a multilayer structure in the beginning but finally it disappeared and an intact BNC tube formed. The mechanical properties of BNC tubes were comparable with the reported value in literatures, demonstrating a great potential in vascular implants or in functional substitutes in biomedicine. PMID:26090420

  8. Complete genome sequence and comparative analysis of Acetobacter pasteurianus 386B, a strain well-adapted to the cocoa bean fermentation ecosystem

    PubMed Central

    2013-01-01

    Background Acetobacter pasteurianus 386B, an acetic acid bacterium originating from a spontaneous cocoa bean heap fermentation, proved to be an ideal functional starter culture for coca bean fermentations. It is able to dominate the fermentation process, thereby resisting high acetic acid concentrations and temperatures. However, the molecular mechanisms underlying its metabolic capabilities and niche adaptations are unknown. In this study, whole-genome sequencing and comparative genome analysis was used to investigate this strain’s mechanisms to dominate the cocoa bean fermentation process. Results The genome sequence of A. pasteurianus 386B is composed of a 2.8-Mb chromosome and seven plasmids. The annotation of 2875 protein-coding sequences revealed important characteristics, including several metabolic pathways, the occurrence of strain-specific genes such as an endopolygalacturonase, and the presence of mechanisms involved in tolerance towards various stress conditions. Furthermore, the low number of transposases in the genome and the absence of complete phage genomes indicate that this strain might be more genetically stable compared with other A. pasteurianus strains, which is an important advantage for the use of this strain as a functional starter culture. Comparative genome analysis with other members of the Acetobacteraceae confirmed the functional properties of A. pasteurianus 386B, such as its thermotolerant nature and unique genetic composition. Conclusions Genome analysis of A. pasteurianus 386B provided detailed insights into the underlying mechanisms of its metabolic features, niche adaptations, and tolerance towards stress conditions. Combination of these data with previous experimental knowledge enabled an integrated, global overview of the functional characteristics of this strain. This knowledge will enable improved fermentation strategies and selection of appropriate acetic acid bacteria strains as functional starter culture for cocoa bean

  9. The Low Biomass Yields of the Acetic Acid Bacterium Acetobacter pasteurianus Are Due to a Low Stoichiometry of Respiration-Coupled Proton Translocation

    PubMed Central

    Luttik, M.; Van Spanning, R.; Schipper, D.; Van Dijken, J. P.; Pronk, J. T.

    1997-01-01

    Growth energetics of the acetic acid bacterium Acetobacter pasteurianus were studied with aerobic, ethanol-limited chemostat cultures. In these cultures, production of acetate was negligible. Carbon limitation and energy limitation were also evident from the observation that biomass concentrations in the cultures were proportional to the concentration of ethanol in the reservoir media. Nevertheless, low concentrations of a few organic metabolites (glycolate, citrate, and mannitol) were detected in culture supernatants. From a series of chemostat cultures grown at different dilution rates, the maintenance energy requirements for ethanol and oxygen were estimated at 4.1 mmol of ethanol (middot) g of biomass(sup-1) (middot) h(sup-1) and 11.7 mmol of O(inf2) (middot) g of biomass(sup-1) (middot) h(sup-1), respectively. When biomass yields were corrected for these maintenance requirements, the Y(infmax) values on ethanol and oxygen were 13.1 g of biomass (middot) mol of ethanol(sup-1) and 5.6 g of biomass (middot) mol of O(inf2)(sup-1), respectively. These biomass yields are very low in comparison with those of other microorganisms grown under comparable conditions. To investigate whether the low growth efficiency of A. pasteurianus might be due to a low gain of metabolic energy from respiratory dissimilation, (symbl)H(sup+)/O stoichiometries were estimated during acetate oxidation by cell suspensions. These experiments indicated an (symbl)H(sup+)/O stoichiometry for acetate oxidation of 1.9 (plusmn) 0.1 mol of H(sup+)/mol of O. Theoretical calculations of growth energetics showed that this low (symbl)H(sup+)/O ratio adequately explained the low biomass yield of A. pasteurianus in ethanol-limited cultures. PMID:16535681

  10. Change of the terminal oxidase from cytochrome a1 in shaking cultures to cytochrome o in static cultures of Acetobacter aceti.

    PubMed

    Matsushita, K; Ebisuya, H; Ameyama, M; Adachi, O

    1992-01-01

    Acetobacter aceti has an ability to grow under two different culture conditions, on shaking submerged cultures and on static pellicle-forming cultures. The respiratory chains of A. aceti grown on shaking and static cultures were compared, especially with respect to the terminal oxidase. Little difference was detected in several oxidase activities and in cytochrome b and c contents between the respiratory chains of both types of cells. Furthermore, the results obtained here suggested that the respiratory chains consist of primary dehydrogenases, ubiquinone, and terminal ubiquinol oxidase, regardless of the culture conditions. There was a remarkable difference, however, in the terminal oxidase, which is cytochrome a1 in cells in shaking culture but cytochrome o in cells grown statically. Change of the culture condition from shaking to static caused a change in the terminal oxidase from cytochrome a1 to cytochrome o, which is concomitant with an increase of pellicle on the surface of the static culture. In contrast, reappearance of cytochrome a1 in A. aceti was attained only after serial successive shaking cultures of an original static culture; cytochrome a1 predominated after the culture was repeated five times. In the culture of A. aceti, two different types of cells were observed; one forms a rough-surfaced colony, and the other forms a smooth-surfaced colony. Cells of the former type predominated in the static culture, while the cells of the latter type predominated in the shaking culture. Thus, data suggest that a change of the culture conditions, from static to shaking or vice versa, results in a change of the cell type, which may be related to the change in the terminal oxidase from cytochrome a1 to cytochrome o in A. aceti.

  11. A kinetic study of the oxidation by molecular oxygen of the cytochrome chain of intact yeast cells, Acetobacter suboxydans cells, and of particulate suspensions of heart muscle.

    PubMed

    Ludwig, G D; Kuby, S A; Edelman, G M; Chance, B

    1983-01-01

    The pre-steady state kinetics of the cytochrome c oxidase reaction with oxygen were studied by a variation in the reaction time between approximately 6 and 25 ms at oxygen concentrations less than 6 mumol/l. For baker's yeast, a pseudo-first-order velocity constant of approximately 150 s-1 at 1.3 mumol/l O2 was obtained corresponding to a second-order reaction between O2 and a3 at a forward velocity constant (k+1) of approximately 3 X 10(7) liter equiv.-1s-1. Thus, the membrane-bound oxidase in the intact cell exhibits one of the most rapid enzyme-substrate reactions to be reported. The value is identical with that of Greenwood and Gibson on an isolated, solubilized cytochrome c oxidase. Similar values of k+1 are calculated from the turnover numbers [k+2 (a+2)] divided by the Km values (formula; see text) measured for these yeast preparations, which points to an almost negligible reverse reaction (k-1) compared to k+2(a+2). Similar calculations for the membrane-bound cytochrome c oxidase of heart muscle give a value of k+1 approximately equal to 10(7) liter equiv.-1s-1. The concordance of the different values of k+1 supports the view that the yeast cell wall does not impart a significant diffusion barrier to the transport of molecular oxygen. In contrast, Acetobacter suboxydans exhibits a much larger value for Km, and has a terminal oxidase of different kinetic parameters.

  12. Reactanceless synthesized impedance bandpass amplifier

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L. (Inventor)

    1985-01-01

    An active R bandpass filter network is formed by four operational amplifier stages interconnected by discrete resistances. One pair of stages synthesize an equivalent input impedance of an inductance (L sub eq) in parallel with a discrete resistance (R sub o) while the second pair of stages synthesizes an equivalent input impedance of a capacitance (C sub eq) serially coupled to another discrete resistance (R sub i) coupled in parallel with the first two stages. The equivalent input impedances aggregately define a tuned resonant bandpass filter in the roll-off regions of the operational amplifiers.

  13. Information Retrieval for Ecological Syntheses

    ERIC Educational Resources Information Center

    Bayliss, Helen R.; Beyer, Fiona R.

    2015-01-01

    Research syntheses are increasingly being conducted within the fields of ecology and environmental management. Information retrieval is crucial in any synthesis in identifying data for inclusion whilst potentially reducing biases in the dataset gathered, yet the nature of ecological information provides several challenges when compared with…

  14. Method of synthesizing pyrite nanocrystals

    DOEpatents

    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.

  15. Laboratory Syntheses of Insect Pheromones.

    ERIC Educational Resources Information Center

    Cormier, Russell A.; Hoban, James N.

    1984-01-01

    Provides background information and procedures for the multi-step synthesis of tiger moth and boll weevil pheromones (sex attractants). These syntheses require several laboratory periods. The tiger moth pheromone synthesis is suitable for introductory organic chemistry while the boll weevil pheromone is recommended for an advanced laboratory…

  16. Information Retrieval for Ecological Syntheses

    ERIC Educational Resources Information Center

    Bayliss, Helen R.; Beyer, Fiona R.

    2015-01-01

    Research syntheses are increasingly being conducted within the fields of ecology and environmental management. Information retrieval is crucial in any synthesis in identifying data for inclusion whilst potentially reducing biases in the dataset gathered, yet the nature of ecological information provides several challenges when compared with…

  17. Laboratory Syntheses of Insect Pheromones.

    ERIC Educational Resources Information Center

    Cormier, Russell A.; Hoban, James N.

    1984-01-01

    Provides background information and procedures for the multi-step synthesis of tiger moth and boll weevil pheromones (sex attractants). These syntheses require several laboratory periods. The tiger moth pheromone synthesis is suitable for introductory organic chemistry while the boll weevil pheromone is recommended for an advanced laboratory…

  18. Method for synthesizing powder materials

    DOEpatents

    Buss, R.J.; Ho, P.

    1988-01-21

    A method for synthesizing ultrafine powder materials, for example, ceramic and metal powders, comprises admitting gaseous reactants from which the powder material is to be formed into a vacuum reaction chamber maintained at a pressure less than atmospheric and at a temperature less than about 400/degree/K (127/degree/C). The gaseous reactants are directed through a glow discharge provided in the vacuum reaction chamber to form the ultrafine powder material. 1 fig.

  19. Determinism in synthesized chaotic waveforms.

    PubMed

    Corron, Ned J; Blakely, Jonathan N; Hayes, Scott T; Pethel, Shawn D

    2008-03-01

    The output of a linear filter driven by a randomly polarized square wave, when viewed backward in time, is shown to exhibit determinism at all times when embedded in a three-dimensional state space. Combined with previous results establishing exponential divergence equivalent to a positive Lyapunov exponent, this result rigorously shows that such reverse-time synthesized waveforms appear equally to have been produced by a deterministic chaotic system.

  20. Catalytic method for synthesizing hydrocarbons

    DOEpatents

    Sapienza, R.S.; Sansone, M.J.; Slegeir, W.A.R.

    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.

  1. Catalytic method for synthesizing hydrocarbons

    DOEpatents

    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.

  2. TSS-Thermal Synthesizer System

    NASA Technical Reports Server (NTRS)

    Chimenti, Edward; Rickman, Steven; Vogt, Robert; Longo, Carlos R. Ortiz; Bauman, Noel; Lepore, Joseph; Mackey, Phil; Pavlovsky, James, II; Welch, Mark; Fogerson, Peter; Dawber, Mark; Fong, Cynthia Jone; Hecke, Peter; Morrison, Susan; Castillo, Ernie; Chou, ZU; Fried, Lawrence; Howard, Jerry; Lombardi, Mike; Middleton, Jack

    1996-01-01

    Thermal Synthesizer System (TSS) is integrated set of thermal-analysis application programs designed to solve problems encountered by thermal engineers. Combines functionality of Systems Improved Numerical Differencing Analyzer/Fluid Integrator (SINDA/FLUINT) and radiation analysis with friendly and easily understood user-interface environment coupled with powerful interactive color graphics and geometric modeling capability. Enables thermal engineers to spend more time solving engineering problems instead of laboriously constructing and verifying math models. Written in FORTRAN and C language.

  3. TSS-Thermal Synthesizer System

    NASA Technical Reports Server (NTRS)

    Chimenti, Edward; Rickman, Steven; Vogt, Robert; Longo, Carlos R. Ortiz; Bauman, Noel; Lepore, Joseph; Mackey, Phil; Pavlovsky, James, II; Welch, Mark; Fogerson, Peter; hide

    1996-01-01

    Thermal Synthesizer System (TSS) is integrated set of thermal-analysis application programs designed to solve problems encountered by thermal engineers. Combines functionality of Systems Improved Numerical Differencing Analyzer/Fluid Integrator (SINDA/FLUINT) and radiation analysis with friendly and easily understood user-interface environment coupled with powerful interactive color graphics and geometric modeling capability. Enables thermal engineers to spend more time solving engineering problems instead of laboriously constructing and verifying math models. Written in FORTRAN and C language.

  4. Solid phase syntheses of oligoureas

    SciTech Connect

    Burgess, K.; Linthicum, D.S.; Russell, D.H.; Shin, H.; Shitangkoon, A.; Totani, R.; Zhang, A.J.; Ibarzo, J.

    1997-02-19

    Isocyanates 7 were formed from monoprotected diamines 3 or 6, which in turn can be easily prepared from commercially available N-BOC- or N-FMOC-protected amino acid derivatives. Isocyanates 7, formed in situ, could be coupled directly to a solid support functionalized with amine groups or to amino acids anchored on resins using CH{sub 2}Cl{sub 2} as solvent and an 11 h coupling time at 25 {degree}C. Such couplings afforded peptidomimetics with an N-phthaloyl group at the N-terminus. The optimal conditions identified for removal of the N-phthaloyl group were to use 60% hydrazine in DMF for 1-3 h. Several sequences of amino acids coupled to ureas (`peptidic ureas`) and of sequential urea units (`oligoureas`) were prepared via solid phase syntheses and isolated by HPLC. Partition coefficients were measured for two of these peptidomimetics, and their water solubilities were found to be similar to the corresponding peptides. A small library of 160 analogues of the YGGFL-amide sequence was prepared via Houghten`s tea bag methodology. This library was tested for binding to the anti-{beta}-endorphin monoclonal antibody. Overall, this paper describes methodology for solid phase syntheses of oligourea derivatives with side chains corresponding to some of the protein amino acids. The chemistry involved is ideal for high-throughput syntheses and screening operations. 51 refs., 3 figs., 2 tabs.

  5. Physiologically driven avian vocal synthesizer

    NASA Astrophysics Data System (ADS)

    Sitt, Jacobo D.; Arneodo, Ezequiel M.; Goller, Franz; Mindlin, Gabriel B.

    2010-03-01

    In this work, we build an electronic syrinx, i.e., a programmable electronic device capable of integrating biomechanical model equations for the avian vocal organ in order to synthesize song. This vocal prosthesis is controlled by the bird’s neural instructions to respiratory and the syringeal motor systems, thus opening great potential for studying motor control and its modification by sensory feedback mechanisms. Furthermore, a well-functioning subject-controlled vocal prosthesis can lay the foundation for similar devices in humans and thus provide directly health-related data and procedures.

  6. Method of synthesizing tungsten nanoparticles

    SciTech Connect

    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.

  7. Information retrieval for ecological syntheses.

    PubMed

    Bayliss, Helen R; Beyer, Fiona R

    2015-06-01

    Research syntheses are increasingly being conducted within the fields of ecology and environmental management. Information retrieval is crucial in any synthesis in identifying data for inclusion whilst potentially reducing biases in the dataset gathered, yet the nature of ecological information provides several challenges when compared with medicine that should be considered when planning and undertaking searches. We present ten recommendations for anyone considering undertaking information retrieval for ecological research syntheses that highlight the main differences with medicine and, if adopted, may help reduce biases in the dataset retrieved, increase search efficiency and improve reporting standards. They are as follows: (1) plan for information retrieval at an early stage, (2) identify and use sources of help, (3) clearly define the question to be addressed, (4) ensure that provisions for managing, recording and reporting the search are in place, (5) select an appropriate search type, (6) identify sources to be used, (7) identify limitations of the sources, (8) ensure that the search vocabulary is appropriate, (9) identify limits and filters that can help direct the search, and (10) test the strategy to ensure that it is realistic and manageable. These recommendations may be of value for other disciplines where search infrastructures are not yet sufficiently well developed. Copyright © 2014 John Wiley & Sons, Ltd.

  8. Cellulose synthesizing Complexes in Vascular Plants andProcaryotes

    SciTech Connect

    Brown, Richard M, Jr; Saxena, Inder Mohan

    2009-07-07

    Continuing the work initiated under DE-FG03-94ER20145, the following major accomplishments were achieved under DE-FG02-03ER15396 from 2003-2007: (a) we purified the acsD gene product of the Acetobacter cellulose synthase operon as well as transferred the CesA cellulose gene from Gossypium into E. coli in an attempt to crystallize this protein for x-ray diffraction structural analysis; however, crystallization attempts proved unsuccessful; (b) the Acetobacter cellulose synthase operon was successfully incorporated into Synechococcus, a cyanobacterium2; (c) this operon in Synechococcus was functionally expressed; (d) we successfully immunolabeled Vigna cellulose and callose synthase components and mapped their distribution before and after wounding; (e) we developed a novel method to produce replicas of cellulose synthases in tobacco BY-2 cells, and we demonstrated the cytoplasmic domain of the rosette TC; (f) from the moss Physcomitrella, we isolated two full-length cDNA sequences of cellulose synthase (PpCesA1 and PpCesA2) and attempted to obtain full genomic DNA sequences; (g) we examined the detailed molecular structure of a new form of non-crystalline cellulose known as nematic ordered cellulose (=NOC)3.

  9. Molecular Syntheses of Extended Materials

    NASA Astrophysics Data System (ADS)

    Paley, Daniel W.

    Bottom-up molecular synthesis is a route to chemically and crystallographically uniform polymers and solid-state materials. Through the use of molecular precursors, we gain atomic-level control of functionality and fine-tuning of the collective properties of materials. This dissertation presents two studies that demonstrate this approach. Ring-opening alkyne metathesis polymerization is a possible approach to monodisperse conjugated polymers, but its applications have been limited by difficult syntheses and high air sensitivity of known organometallic ROAMP initiators. We designed a dimeric, air-stable molybdenum alkylidyne with a tris(phenolate) supporting ligand. The precatalyst is activated by addition of methanol and polymerizes cyclooctynes with excellent chemical selectivity and functional group tolerance. The Nuckolls and Roy groups have introduced a new family of solid-state compounds synthesized from cobalt chalcogenide clusters Co6Q 8(PR3)6 and fullerenes. The first examples of these materials crystallized in superatom lattices with the symmetry of simple inorganic solids CdI2 (P-3m1) and NaCl (Fm-3m). This dissertation reveals that further members of the family feature extraordinary diversity of structure, including a pseudo-trigonal array of fulleride dimers in [Co 6Te8(PEt3)6]2[C140 ][C70]2 and a heterolayered van der Waals cocrystal [Co6Se8(PEt2phen)6][C 60]5. In addition to these unusual crystal structures, this dissertation presents a method for assigning redox states from crystallographic data in Co6Q8 clusters. Finally, a detailed guide to the collection and solution of single-crystal X-ray data is presented. The guide is intended for independent study by new crystallographers.

  10. A novel Na(+)(K(+))/H(+) antiporter plays an important role in the growth of Acetobacter tropicalis SKU1100 at high temperatures via regulation of cation and pH homeostasis.

    PubMed

    Soemphol, Wichai; Tatsuno, Maki; Okada, Takahiro; Matsutani, Minenosuke; Kataoka, Naoya; Yakushi, Toshiharu; Matsushita, Kazunobu

    2015-10-10

    A gene encoding a putative Na(+)/H(+) antiporter was previously proposed to be involved in the thermotolerance mechanism of Acetobacter tropicalis SKU 1100. The results of this study show that disruption of this antiporter gene impaired growth at high temperatures with an external pH>6.5. The growth impairment at high temperatures was much more severe in the absence of Na(+) (with only the presence of K(+)); under these conditions, cells failed to grow even at 30°C and neutral to alkaline pH values, suggesting that this protein is also important for K(+) tolerance. Functional analysis with inside-out membrane vesicles from wild type and mutant strains indicated that the antiporter, At-NhaK2 operates as an alkali cation/proton antiporter for ions such as Na(+), K(+), Li(+), and Rb(+) at acidic to neutral pH values (6.5-7.5). The membrane vesicles were also shown to contain a distinct pH-dependent Na(+)(specific)/H(+) antiporter(s) that might function at alkaline pH values. In addition, phylogenetic analysis showed that At-NhaK2 is a novel type of Na(+)/H(+) antiporter belonging to a phylogenetically distinct new clade. These data demonstrate that At-NhaK2 functions as a Na(+)(K(+))/H(+) antiporter and is essential for K(+) and pH homeostasis during the growth of A. tropicalis SKU1100, especially at higher temperatures.

  11. Synthese de champs sonores adaptative

    NASA Astrophysics Data System (ADS)

    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

  12. Laser-synthesized epitaxial graphene.

    PubMed

    Lee, Sangwon; Toney, Michael F; Ko, Wonhee; Randel, Jason C; Jung, Hee Joon; Munakata, Ko; Lu, Jesse; Geballe, Theodore H; Beasley, Malcolm R; Sinclair, Robert; Manoharan, Hari C; Salleo, Alberto

    2010-12-28

    Owing to its unique electronic properties, graphene has recently attracted wide attention in both the condensed matter physics and microelectronic device communities. Despite intense interest in this material, an industrially scalable graphene synthesis process remains elusive. Here, we demonstrate a high-throughput, low-temperature, spatially controlled and scalable epitaxial graphene (EG) synthesis technique based on laser-induced surface decomposition of the Si-rich face of a SiC single-crystal. We confirm the formation of EG on SiC as a result of excimer laser irradiation by using reflection high-energy electron diffraction (RHEED), Raman spectroscopy, synchrotron-based X-ray diffraction, transmission electron microscopy (TEM), and scanning tunneling microscopy (STM). Laser fluence controls the thickness of the graphene film down to a single monolayer. Laser-synthesized graphene does not display some of the structural characteristics observed in EG grown by conventional thermal decomposition on SiC (0001), such as Bernal stacking and surface reconstruction of the underlying SiC surface.

  13. Microbial Cellulose Assembly in Microgravity

    NASA Technical Reports Server (NTRS)

    Brown, R. Malcolm, Jr.

    1998-01-01

    Based on evidence indicating a possible correlation between hypo-gravity conditions and alteration of cellulose production by the gram negative bacterium, Acetobacter xylinum, a ground-based study for a possible long term Space Shuttle flight has been conducted. The proposed experiment for A. xylinum aboard the Shuttle is the BRIC (Biological Research in a Canister), a metal container containing spaces for nine Petri plates. Using a common experimental design, the cellulose production capability as well as the survivability of the A. xylinum strains NQ5 and AY201 have been described. It should now be possible to use the BRIC for the first long term microgravity experiments involving the biosynthesis of cellulose.

  14. Synthesizing Diamond from Liquid Feedstock

    NASA Technical Reports Server (NTRS)

    Tzeng, Yonhua

    2005-01-01

    A relatively economical method of chemical vapor deposition (CVD) has been developed for synthesizing diamond crystals and films. Unlike prior CVD methods for synthesizing diamond, this method does not require precisely proportioned flows of compressed gas feedstocks or the use of electrical discharges to decompose the feedstocks to obtain free radicals needed for deposition chemical reactions. Instead, the feedstocks used in this method are mixtures of common organic liquids that can be prepared in advance, and decomposition of feedstock vapors is effected simply by heating. The feedstock used in this method is a solution comprising between 90 and 99 weight percent of methanol and the balance of one or more other oxyhydrocarbons that could include ethanol, isopropanol, and/or acetone. This mixture of compounds is chosen so that dissociation of molecules results in the desired proportions of carbon-containing radicals (principally, CH3) and of OH, H, and O radicals. Undesirably, the CVD temperature and pressure conditions thermodynamically favor the growth of graphite over the growth of diamond. The H radicals are desirable because they help to stabilize the growing surface of diamond by shifting the thermodynamic balance toward favoring the growth of diamond. The OH and O radicals are desirable because they preferentially etch graphite and other non-diamond carbon, thereby helping to ensure the net deposition of pure diamond. The non-methanol compounds are included in the solution because (1) methanol contains equal numbers of C and O atoms; (2) an excess of C over O is needed to obtain net deposition of diamond; and (3) the non-methanol molecules contain multiple carbon atoms for each oxygen atom and thus supply the needed excess carbon A typical apparatus used in this method includes a reservoir containing the feedstock liquid and a partially evacuated stainless-steel reaction chamber. The reservoir is connected to the chamber via tubing and a needle valve or

  15. A specialized citric acid cycle requiring succinyl-coenzyme A (CoA):acetate CoA-transferase (AarC) confers acetic acid resistance on the acidophile Acetobacter aceti.

    PubMed

    Mullins, Elwood A; Francois, Julie A; Kappock, T Joseph

    2008-07-01

    Microbes tailor macromolecules and metabolism to overcome specific environmental challenges. Acetic acid bacteria perform the aerobic oxidation of ethanol to acetic acid and are generally resistant to high levels of these two membrane-permeable poisons. The citric acid cycle (CAC) is linked to acetic acid resistance in Acetobacter aceti by several observations, among them the oxidation of acetate to CO2 by highly resistant acetic acid bacteria and the previously unexplained role of A. aceti citrate synthase (AarA) in acetic acid resistance at a low pH. Here we assign specific biochemical roles to the other components of the A. aceti strain 1023 aarABC region. AarC is succinyl-coenzyme A (CoA):acetate CoA-transferase, which replaces succinyl-CoA synthetase in a variant CAC. This new bypass appears to reduce metabolic demand for free CoA, reliance upon nucleotide pools, and the likely effect of variable cytoplasmic pH upon CAC flux. The putative aarB gene is reassigned to SixA, a known activator of CAC flux. Carbon overflow pathways are triggered in many bacteria during metabolic limitation, which typically leads to the production and diffusive loss of acetate. Since acetate overflow is not feasible for A. aceti, a CO(2) loss strategy that allows acetic acid removal without substrate-level (de)phosphorylation may instead be employed. All three aar genes, therefore, support flux through a complete but unorthodox CAC that is needed to lower cytoplasmic acetate levels.

  16. Structure of bacterial cellulose synthase subunit D octamer with four inner passageways

    PubMed Central

    Hu, Song-Qing; Gao, Yong-Gui; Tajima, Kenji; Sunagawa, Naoki; Zhou, Yong; Kawano, Shin; Fujiwara, Takaaki; Yoda, Takanori; Shimura, Daisuke; Satoh, Yasuharu; Munekata, Masanobu; Tanaka, Isao; Yao, Min

    2010-01-01

    The cellulose synthesizing terminal complex consisting of subunits A, B, C, and D in Acetobacter xylinum spans the outer and inner cell membranes to synthesize and extrude glucan chains, which are assembled into subelementary fibrils and further into a ribbon. We determined the structures of subunit D (AxCeSD/AxBcsD) with both N- and C-terminal His6 tags, and in complex with cellopentaose. The structure of AxCeSD shows an exquisite cylinder shape (height: ∼65 Å, outer diameter: ∼90 Å, and inner diameter: ∼25 Å) with a right-hand twisted dimer interface on the cylinder wall, formed by octamer as a functional unit. All N termini of the octamer are positioned inside the AxCeSD cylinder and create four passageways. The location of cellopentaoses in the complex structure suggests that four glucan chains are extruded individually through their own passageway along the dimer interface in a twisted manner. The complex structure also shows that the N-terminal loop, especially residue Lys6, seems to be important for cellulose production, as confirmed by in vivo assay using mutant cells with axcesD gene disruption and N-terminus truncation. Taking all results together, a model of the bacterial terminal complex is discussed. PMID:20921370

  17. Synthesizing Regression Results: A Factored Likelihood Method

    ERIC Educational Resources Information Center

    Wu, Meng-Jia; Becker, Betsy Jane

    2013-01-01

    Regression methods are widely used by researchers in many fields, yet methods for synthesizing regression results are scarce. This study proposes using a factored likelihood method, originally developed to handle missing data, to appropriately synthesize regression models involving different predictors. This method uses the correlations reported…

  18. "Comments on Slavin": Synthesizing Causal Inferences

    ERIC Educational Resources Information Center

    Briggs, Derek C.

    2008-01-01

    When causal inferences are to be synthesized across multiple studies, efforts to establish the magnitude of a causal effect should be balanced by an effort to evaluate the generalizability of the effect. The evaluation of generalizability depends on two factors that are given little attention in current syntheses: construct validity and external…

  19. Composites comprising biologically-synthesized nanomaterials

    DOEpatents

    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.

  20. Synthesizing Regression Results: A Factored Likelihood Method

    ERIC Educational Resources Information Center

    Wu, Meng-Jia; Becker, Betsy Jane

    2013-01-01

    Regression methods are widely used by researchers in many fields, yet methods for synthesizing regression results are scarce. This study proposes using a factored likelihood method, originally developed to handle missing data, to appropriately synthesize regression models involving different predictors. This method uses the correlations reported…

  1. Syntheses of Novel Nitrogen and Phosphorus Heterocycles.

    DTIC Science & Technology

    2014-09-26

    Chemicals and Materials Research Department, Ultrasystems, Inc. under Contract F49620-82-C-0021, "Syntheses of Novel Nitrogen and Phosphorus Hetero- * cycles ...ADl-NISS9 449 SYNTHESES OF NOVEL NITROGEN AND PHOSPHORUS HETEROCYCLES In (U) ULTRRSYSTENS INC IRVINE CR K L PRCIOREK ET RL. 26 RPR 85 SN-209?-F RFOSR...MICROCOPY RESOLUTION TEST CHART NATIONAL BURE&U OF STAOACS-963-A SR-I"I" s, -Ŕ 500 4 SYNTHESES OF NOVEL NITROGEN AND PHOSPHORUS HETEROCYCLES Contract No

  2. The Trajectory Synthesizer Generalized Profile Interface

    NASA Technical Reports Server (NTRS)

    Lee, Alan G.; Bouyssounouse, Xavier; Murphy, James R.

    2010-01-01

    The Trajectory Synthesizer is a software program that generates aircraft predictions for Air Traffic Management decision support tools. The Trajectory Synthesizer being used by researchers at NASA Ames Research Center was restricted in the number of trajectory types that could be generated. This limitation was not sufficient to support the rapidly changing Air Traffic Management research requirements. The Generalized Profile Interface was developed to address this issue. It provides a flexible approach to describe the constraints applied to trajectory generation and may provide a method for interoperability between trajectory generators. It also supports the request and generation of new types of trajectory profiles not possible with the previous interface to the Trajectory Synthesizer. Other enhancements allow the Trajectory Synthesizer to meet the current and future needs of Air Traffic Management research.

  3. Thermoelectric Properties of Solution Synthesized Nanostructured Materials.

    PubMed

    Finefrock, Scott W; Yang, Haoran; Fang, Haiyu; Wu, Yue

    2015-01-01

    Thermoelectric nanocomposites made by solution synthesis and compression of nanostructured chalcogenides could potentially be low-cost, scalable alternatives to traditional solid-state synthesized materials. We review the progress in this field by comparing the power factor and/or the thermoelectric figure of merit, ZT, of four classes of materials: (Bi,Sb)2(Te,Se)3, PbTe, ternary and quaternary copper chalcogenides, and silver chalcogenides. We also discuss the thermal conductivity reduction associated with multiphased nanocomposites. The ZT of the best solution synthesized materials are, in several cases, shown to be equal to or greater than the corresponding bulk materials despite the generally reduced mobility associated with solution synthesized nanocomposites. For the solution synthesized materials with the highest performance, the synthesis and processing conditions are summarized to provide guidance for future work.

  4. ORGANIC SYNTHESES USING MICROWAVES AND SUPPORTED REAGENTS

    EPA Science Inventory

    Microwave-accelerated chemical syntheses under solvent-free conditions have witnessed an explosive growth. The technique has found widespread application predominantly exploiting the inexpensive unmodified household microwave (MW) ovens although the use of dedicated MW equipment...

  5. ORGANIC SYNTHESES USING MICROWAVES AND SUPPORTED REAGENTS

    EPA Science Inventory

    Microwave-accelerated chemical syntheses under solvent-free conditions have witnessed an explosive growth. The technique has found widespread application predominantly exploiting the inexpensive unmodified household microwave (MW) ovens although the use of dedicated MW equipment...

  6. Method to synthesize metal chalcogenide monolayer nanomaterials

    SciTech Connect

    Hernandez-Sanchez, Bernadette A.; Boyle, Timothy J.

    2016-12-13

    Metal chalcogenide monolayer nanomaterials can be synthesized from metal alkoxide precursors by solution precipitation or solvothermal processing. The synthesis routes are more scalable, less complex and easier to implement than other synthesis routes.

  7. Psychoacoustic Analysis of Synthesized Jet Noise

    NASA Technical Reports Server (NTRS)

    Okcu, Selen; Rathsam, Jonathan; Rizzi, Stephen A.

    2013-01-01

    An aircraft noise synthesis capability is being developed so the annoyance caused by proposed aircraft can be assessed during the design stage. To make synthesized signals as realistic as possible, high fidelity simulation is required for source (e.g., engine noise, airframe noise), propagation and receiver effects. This psychoacoustic study tests whether the jet noise component of synthesized aircraft engine noise can be made more realistic using a low frequency oscillator (LFO) technique to simulate fluctuations in level observed in recordings. Jet noise predictions are commonly made in the frequency domain based on models of time-averaged empirical data. The synthesis process involves conversion of the frequency domain prediction into an audible pressure time history. However, because the predictions are time-invariant, the synthesized sound lacks fluctuations observed in recordings. Such fluctuations are hypothesized to be perceptually important. To introduce time-varying characteristics into jet noise synthesis, a method has been developed that modulates measured or predicted 1/3-octave band levels with a (<20Hz) LFO. The LFO characteristics are determined through analysis of laboratory jet noise recordings. For the aft emission angle, results indicate that signals synthesized using a generic LFO are perceived as more similar to recordings than those using no LFO, and signals synthesized with an angle-specific LFO are more similar to recordings than those synthesized with a generic LFO.

  8. Stereo matching image processing by synthesized color and the characteristic area by the synthesized color

    NASA Astrophysics Data System (ADS)

    Akiyama, Akira; Mutoh, Eiichiro; Kumagai, Hideo

    2014-09-01

    We have developed the stereo matching image processing by synthesized color and the corresponding area by the synthesized color for ranging the object and image recognition. The typical images from a pair of the stereo imagers may have some image disagreement each other due to the size change, missed place, appearance change and deformation of characteristic area. We constructed the synthesized color and corresponding color area with the same synthesized color to make the distinct stereo matching. We constructed the synthesized color and corresponding color area with the same synthesized color by the 3 steps. The first step is making binary edge image by differentiating the focused image from each imager and verifying that differentiated image has normal density of frequency distribution to find the threshold level of binary procedure. We used Daubechies wavelet transformation for the procedures of differentiating in this study. The second step is deriving the synthesized color by averaging color brightness between binary edge points with respect to horizontal direction and vertical direction alternatively. The averaging color procedure was done many times until the fluctuation of averaged color become negligible with respect to 256 levels in brightness. The third step is extracting area with same synthesized color by collecting the pixel of same synthesized color and grouping these pixel points by 4 directional connectivity relations. The matching areas for the stereo matching are determined by using synthesized color areas. The matching point is the center of gravity of each synthesized color area. The parallax between a pair of images is derived by the center of gravity of synthesized color area easily. The experiment of this stereo matching was done for the object of the soccer ball toy. From this experiment we showed that stereo matching by the synthesized color technique are simple and effective.

  9. VCO PLL Frequency Synthesizers for Spacecraft Transponders

    NASA Technical Reports Server (NTRS)

    Smith, Scott; Mysoor, Narayan; Lux, James; Cook, Brian

    2007-01-01

    Two documents discuss a breadboard version of advanced transponders that, when fully developed, would be installed on future spacecraft to fly in deep space. These transponders will be required to be capable of operation on any deepspace- communications uplink frequency channel between 7,145 and 7,235 MHz, and any downlink frequency channel between 8,400 and 8,500 MHz. The document focuses on the design and operation of frequency synthesizers for the receiver and transmitter. Heretofore, frequency synthesizers in deep-space transponders have been based on dielectric resonator oscillators (DROs), which do not have the wide tuning bandwidth necessary to tune over all channels in the uplink or downlink frequency bands. To satisfy the requirement for tuning bandwidth, the present frequency synthesizers are based on voltage-controlled-oscillator (VCO) phase-locked loops (PLLs) implemented by use of monolithic microwave integrated circuits (MMICs) implemented using inGaP heterojunction bipolar transistor (HBT) technology. MMIC VCO PLL frequency synthesizers similar to the present ones have been used in commercial and military applications but, until now, have exhibited too much phase noise for use in deep-space transponders. The present frequency synthesizers contain advanced MMIC VCOs, which use HBT technology and have lower levels of flicker (1/f) phase noise. When these MMIC VCOs are used with high-speed MMIC frequency dividers, it becomes possible to obtain the required combination of frequency agility and low phase noise.

  10. Characterization of synthesized and treated gem diamonds

    NASA Astrophysics Data System (ADS)

    Song, Ohsung

    2007-10-01

    Synthesized diamonds have been widely employed as polishing media for precise machining and noble substrates for microelectronics. The recent development of the split sphere press has led to the commercial HPHT (high pressure high temperature) synthesis of bulk gem diamonds from graphite and to the enhancement of low quality natural diamonds. Synthesized and treated diamonds are sometimes traded deceptively as high quality natural diamonds because it is hard to distinguish among these diamonds with conventional gemological characterization methods. Therefore, we need to develop a new identification method that is non-destructive, fast, and inexpensive. We proposed using new methods of UV fluorescence and X-ray Lang topography for checking the local HPHT stress field as well as using a vibrating sample magnetometer for checking ferromagnetic residue in synthesized diamonds to distinguish these diamonds from natural ones. We observe unique differences in the local stress field images in synthesized and treated diamonds using Lang topography and UV fluorescence characterization. Our result implies that our proposed methods may be appropriate for identification of the synthesized and treated diamonds.

  11. Localization performance with synthesized directional audio

    NASA Astrophysics Data System (ADS)

    Agnew, Jeffrey R.; German, Valencia; Calhoun, Gloria L.; Ericson, Mark A.

    1990-07-01

    This report summarizes three studies designed to measure and compare the ability of subjects to localize sounds in azimuth, via headphones, generated by two prototype auditory localization cue synthesizers. In the first study, performance differences were found between the two synthesizers in certain areas of the azimuth plane. Additionally, the design of a synthesizer (e.g., resolution and interpolating between head-related transfer functions (HRTF's)) can impact the perceived direction of the acoustic signals. Previous research with directional audio suggests that the veridicality of 3-D auditory displays could be optimized if individualized HRTF's are employed to synthesize the virtual sound sources, particularly in elevation. However, data from this experiment suggest that this design requirement can be relaxed, especially if only azimuth information is to be conveyed by the localization synthesizer. In the second study, two response methods for measuring localization performance were evaluated. No performance differences were found when subjects either verbally reported angular estimates or pointed to a circle to indicate the perceived direction of the target stimuli. In the third study, performance was impacted by manipulating the bandwidth of the acoustic signal and head movement.

  12. Bacterial cellulose and bacterial cellulose-chitosan membranes for wound dressing applications.

    PubMed

    Lin, Wen-Chun; Lien, Chun-Chieh; Yeh, Hsiu-Jen; Yu, Chao-Ming; Hsu, Shan-Hui

    2013-04-15

    Bacterial cellulose (BC) and bacterial cellulose-chitosan (BC-Ch) membranes were successfully produced in large scale. BC was synthesized by Acetobacter xylinum. BC-Ch was prepared by immersing BC in chitosan followed by freeze-drying. The surface morphology of BC and BC-Ch membranes were examined by a scanning electron microscope (SEM). SEM images showed that BC-Ch possessed a denser fibril network with smaller pores than BC. Infrared spectroscopy was used to confirm the incorporation of chitosan in BC-Ch. The swelling behavior, water retention capacity, and mechanical properties of BC and BC-Ch were further evaluated. Results indicated that both membranes maintained proper moisture contents for an extensive period without dehydration. The tensile strength and elongation at break for BC-Ch were slightly lower while the Young's modulus was higher. Cell culture studies demonstrated that BC and BC-Ch had no cytotoxicity. In the antibacterial test, the addition of chitosan in BC showed significant growth inhibition against Escherichia coli and Staphylococcus aureus. The effects of BC and BC-Ch on skin wound healing were assessed by rat models. Histological examinations revealed that wounds treated with BC-Ch epithelialized and regenerated faster than those treated with BC or Tegaderm. Therefore, BC-Ch was considered as a potential candidate for wound dressing materials.

  13. Modification of Bacterial Cellulose with Organosilanes to Improve Attachment and Spreading of Human Fibroblasts

    PubMed Central

    Taokaew, Siriporn; Phisalaphong, Muenduen; Newby, Bi-min Zhang

    2015-01-01

    Bacterial Cellulose (BC) synthesized by Acetobacter xylinum has been a promising candidate for medical applications. Modifying BC to possess the properties needed for specific applications has been reported. In this study, BCs functionalized by organosilanes were hypothesized to improve the attachment and spreading of Normal Human Dermal Fibroblast (NHDF). The BC gels obtained from biosynthesis were dried by either ambient-air drying or freeze drying. The surfaces of those dried BCs were chemically modified by grafting methyl terminated octadecyltrichlorosilane (OTS) or amine terminated 3-aminopropyltriethoxysilane (APTES) to expectedly increase hydrophobic or electrostatic interactions with NHDF cells, respectively. NHDF cells improved their attachment and spreading on the majority of APTES-modified BCs (∼70-80% of area coverage by cells) with more rapid growth (∼2.6-2.8× after incubations from 24 to 48h) than on tissue culture polystyrene (∼2×); while the inverse results (< 5% of area coverage and stationary growth) were observed on the OTS-modified BCs. For organosilane modified BCs, the drying method had no effect on in vitro cell attachment/spreading behaviors. PMID:26478661

  14. Synthesize, Synthesize, Synthesize.

    ERIC Educational Resources Information Center

    Nugent, Susan Monroe, Ed.

    1987-01-01

    Focusing on synthesis--the ability to recognize and create new ideas that subsume and relate to others--as one of the most sophisticated skills writers can attain, the articles in this journal present many ideas for teaching synthesis and a number of classroom approaches that combine the study of English with other fields. The following titles and…

  15. Synthesize, Synthesize, Synthesize.

    ERIC Educational Resources Information Center

    Nugent, Susan Monroe, Ed.

    1987-01-01

    Focusing on synthesis--the ability to recognize and create new ideas that subsume and relate to others--as one of the most sophisticated skills writers can attain, the articles in this journal present many ideas for teaching synthesis and a number of classroom approaches that combine the study of English with other fields. The following titles and…

  16. A Scalable High-Throughput Chemical Synthesizer

    PubMed Central

    Livesay, Eric A.; Liu, Ying-Horng; Luebke, Kevin J.; Irick, Joel; Belosludtsev, Yuri; Rayner, Simon; Balog, Robert; Johnston, Stephen Albert

    2002-01-01

    A machine that employs a novel reagent delivery technique for biomolecular synthesis has been developed. This machine separates the addressing of individual synthesis sites from the actual process of reagent delivery by using masks placed over the sites. Because of this separation, this machine is both cost-effective and scalable, and thus the time required to synthesize 384 or 1536 unique biomolecules is very nearly the same. Importantly, the mask design allows scaling of the number of synthesis sites without the addition of new valving. Physical and biological comparisons between DNA made on a commercially available synthesizer and this unit show that it produces DNA of similar quality. PMID:12466300

  17. An automated Teflon microfluidic peptide synthesizer.

    PubMed

    Zheng, Hui; Wang, Weizhi; Li, Xiaojun; Wang, Zihua; Hood, Leroy; Lausted, Christopher; Hu, Zhiyuan

    2013-09-07

    We present a microfluidic synthesizer made entirely of Teflon material for solid phase peptide synthesis (SPPS). Solvent-resistant perfluoroalkoxy (PFA) was used to construct chip-sized devices featuring multiple tri-layer pneumatic microvalves. Using these devices, model peptides were automatically synthesized and cleaved in situ in a continuous-flow manner. The total coupling and cleavage time was significantly reduced compared to conventional bulk reactors. The synthesis of a decapeptide, for instance, took less than 6 h using our device while it usually takes more than three days using conventional reactors.

  18. Evaluating Text-to-Speech Synthesizers

    ERIC Educational Resources Information Center

    Cardoso, Walcir; Smith, George; Fuentes, Cesar Garcia

    2015-01-01

    Text-To-Speech (TTS) synthesizers have piqued the interest of researchers for their potential to enhance the L2 acquisition of writing (Kirstein, 2006), vocabulary and reading (Proctor, Dalton, & Grisham, 2007) and pronunciation (Cardoso, Collins, & White, 2012; Soler-Urzua, 2011). Despite their proven effectiveness, there is a need for…

  19. Digital Frequency Synthesizer For Radar Astronomy

    NASA Technical Reports Server (NTRS)

    Sadr, Ramin; Satorius, Edgar; Robinett, J. Loris, Jr.; Olson, Erlend

    1992-01-01

    Report discusses conceptual digital frequency synthesizer part of programmable local oscillator in radar-astronomy system. Phase must remain continuous during adjustments of frequency, phase noise must be low, and spectral purity must be high. Discusses theory of operation in some mathematical detail and presents new analysis of spectral purity of output.

  20. Method and apparatus for synthesizing filamentary structures

    DOEpatents

    Height, Murray J [Somerville, MA; Howard, Jack B [Winchester, MA; Vandersande, John B [Newbury, MA

    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.

  1. Method and apparatus for synthesizing filamentary structures

    DOEpatents

    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.

  2. Synthesizing Diacetylenes With Nonlinear Optical Properties

    NASA Technical Reports Server (NTRS)

    Mcmanus, Samuel P.; Frazier, Donald P.; Paley, Mark S.

    1993-01-01

    Diacetylene compounds being investigated to determine whether they have nonlinear optical properties making them useful for four-wave mixing, generation of third harmonics, phase conjugation, and like. Diacetylene monomers synthesized by sequences of chemical reactions. Monomers polymerized by ultraviolet light, forming potentially useful nonlinear optical materials.

  3. Syntheses of novel substituted-boranophosphate nucleosides.

    PubMed

    Vyakaranam, Kamesh; Rana, Geeta; Spielvogel, Bernard F; Maguire, John A; Hosmane, Narayan S

    2002-01-01

    A number of substituted (borano) nucleic acids, 3'-[diethylphosphite(cyano, carboxy, or carbamoyl) borano] deoxynucleosides (3a-4c) and 5'-[diethylphosphite(cyano or carboxy) borano] deoxynucleosides (6a-7d) were prepared by a variety of synthetic procedures. The syntheses of the pyrophosphates (2a-2c), as precursors for 3a-4c, are also described.

  4. Concise total syntheses of (+/-)-strychnine and (+/-)-akuammicine.

    PubMed

    Sirasani, Gopal; Paul, Tapas; Dougherty, William; Kassel, Scott; Andrade, Rodrigo B

    2010-05-21

    Concise total syntheses of Strychnos alkaloids strychnine (1) and akuammicine (2) have been realized in 13 and 6 operations, respectively. Key steps include (1) the vinylogous Mannich reaction; (2) a novel, sequential one-pot spirocyclization/intramolecular aza-Baylis-Hillman reaction; and (3) a Heck cyclization. The synthesis of 1 proceeds via the Wieland-Gumlich aldehyde (26).

  5. Synthesizing analytic evidence to refine care pathways.

    PubMed

    Liu, Haifeng; Li, Xiang; Yu, Yiqin; Mei, Jing; Xie, Guotong; Perer, Adam; Wang, Fei; Hu, Jianying

    2015-01-01

    Care pathways play significant roles in delivering evidence-based and coordinated care to patients with specific conditions. In order to put care pathways into practice, clinical institutions always need to adapt them based on local care settings so that the best local practices can be incorporated and used to develop refined pathways. However, it is knowledge-intensive and error-prone to incorporate various analytic insights from local data sets. In order to assist care pathway developers in working effectively and efficiently, we propose to automatically synthesize the analytical evidences derived from multiple analysis methods, and recommend modelling operations accordingly to derive a refined care pathway for a specific patient cohort. We validated our method by adapting a Congestive Heart Failure (CHF) Ambulatory Care Pathway for patients with additional condition of COPD through synthesizing the results of variation analysis and frequent pattern mining against patient records.

  6. Biofunctionalization and capping of template synthesized nanotubes.

    PubMed

    Hillebrenner, Heather; Buyukserin, Fatih; Stewart, Jon D; Martin, Charles R

    2007-07-01

    Using alumina templates both nanotubes (open on both ends) and nano test tubes (open on only one end) have been synthesized from many different materials and these have great potential as delivery vehicles for biomedical applications. This review focuses on our recent results directed towards developing "smart" nanotubes for biomolecule delivery applications. While intensive efforts have focused on spherical nanoparticles that are easier to make, cylindrical particles or nanotubes offer many advantages. First, the tunable alumina template allows one to dictate both the pore diameter and length of the nanotube. In addition, template synthesized nanotubes can be differentially functionalized on their inner and outer surfaces. This review highlights these advantages in the contexts of drug extraction and antibody-antigen interactions, the synthesis of protein nanotubes, and recent advances in covalently capped ("corked") nanotubes designed to prevent premature payload leakage. Though diverse applications for nanotubes have already been discovered, many new and exciting paths await exploration.

  7. BRUCE/KYLIE: Pulsating star spectra synthesizer

    NASA Astrophysics Data System (ADS)

    Townsend, Rich

    2014-12-01

    BRUCE and KYLIE, written in Fortran 77, synthesize the spectra of pulsating stars. BRUCE constructs a point-sampled model for the surface of a rotating, gravity-darkened star, and then subjects this model to perturbations arising from one or more non-radial pulsation modes. Departures from adiabaticity can be taken into account, as can the Coriolis force through adoption of the so-called traditional approximation. BRUCE writes out a time-sequence of perturbed surface models. This sequence is read in by KYLIE, which synthesizes disk-integrated spectra for the models by co-adding the specific intensity emanating from each visible point toward the observer. The specific intensity is calculated by interpolation in a large temperature-gravity-wavelength-angle grid of pre-calculated intensity spectra.

  8. (m.n)-Homorubins. Syntheses and Structures

    PubMed Central

    Pfeiffer, William P.

    2014-01-01

    Five new homorubin analogs of bilirubin with their two dipyrrinone components conjoined to (CH2)2, (CH2)3, and (CH2)4 units were synthesized with propionic acid chains shortened to acetic and elongated to butyric, and examined by spectroscopy and molecular mechanics computations for an ability to form conformation-determining hydrogen bonds. With m designating the number of conjoining CH2 units and n indicating the number of CH2 units of the alkanoic acid chains of (m.n)-homorubins, (2.1), (3.2), (4.2), and (4.3) homorubins were prepared and compared with previously synthesized (2.2) and (2.3), which adopt intramolecularly hydrogen bonded conformations in CHCl3. PMID:25544780

  9. Maize mitochondria synthesize organ-specific polypeptides

    SciTech Connect

    Newton, K.J.; Walbot, V.

    1985-10-01

    The authors detected both quantitative and qualitative organ-specific differences in the total protein composition of mitochondria of maize. Labeling of isolated mitochondria from each organ demonstrated that a few protein differences are due to changes in the polypeptides synthesized by the organelle. The synthesis of developmental stage-specific mitochondrial polypeptides was found in the scutella of developing and germinating kernels. The approximately 13-kDa polypeptide synthesized by mitochondria from seedlings of the Texas (T) male-sterile cytoplasm was shown to be constitutively expressed in all organs of line B37T tested. Methomyl, an insecticide known to inhibit the growth of T sterile plants, was shown to be an effective inhibitor of protein synthesis in mitochondria from T plants.

  10. Syntheses and studies of organosilicon compounds

    SciTech Connect

    Xie, Ren

    1999-02-12

    The syntheses of polycarbosilanes and polysilanes as silicon carbide ceramic precursors have been active research areas in the Barton Research Group. In this thesis, the work is focused on the preparation of polycarbosilanes and polysilanes as stoichiometric silicon carbide precursor polymers. The syntheses of the precursor polymers are discussed and the conversions of these precursors to silicon carbide via pyrolysis are reported. The XRD pattern and elemental analyses of the resulting silicon carbide ceramics are presented. Silicon monoxide is an important intermediate in the production of silicon metal. The existence of silicon monoxide in gap phase has been widely accepted. In the second part of this thesis, the generation of gaseous silicon monoxide in four different reactors and the reactions of gaseous silicon monoxide towards organic compounds are discussed.

  11. Genome Mining for Ribosomally Synthesized Natural Products

    PubMed Central

    Velásquez, Juan E.; van der Donk, Wilfred

    2011-01-01

    In recent years, the number of known peptide natural products that are synthesized via the ribosomal pathway has rapidly grown. Taking advantage of sequence homology among genes encoding precursor peptides or biosynthetic proteins, in silico mining of genomes combined with molecular biology approaches has guided the discovery of a large number of new ribosomal natural products, including lantipeptides, cyanobactins, linear thiazole/oxazole-containing peptides, microviridins, lasso peptides, amatoxins, cyclotides, and conopeptides. In this review, we describe the strategies used for the identification of these ribosomally-synthesized and posttranslationally modified peptides (RiPPs) and the structures of newly identified compounds. The increasing number of chemical entities and their remarkable structural and functional diversity may lead to novel pharmaceutical applications. PMID:21095156

  12. Method of synthesizing a low density material

    DOEpatents

    Lorensen, L.E.; Monaco, S.B.

    1987-02-27

    A novel method of synthesizing a polymeric material of low density of the order of 50mg/cc or less. Such a low density material has applications in many areas including laser target fabrication. The method comprises preparing a polymer blend of two incompatible polymers as a major and a minor phase by mixing them and extruding the mixture, and then selectively extracting the major component, to yield a fine, low density structure.

  13. Interference coatings based on synthesized silicon nitride.

    PubMed

    Lee, C C; Chen, H L; Hsu, J C; Tien, C L

    1999-04-01

    Silicon nitrides are synthesized by ion-assisted deposition with only one coating material and a nitrogen-ion-beam source. All the SiN(x) films are amorphous and mechanically strong. A wide range of refractive indices from 3.43 to 1.72 at a wavelength of 1550 nm is obtained. Near-IR antireflection coating and a bandpass filter based on the multilayers of SiN(x) and Si are demonstrated.

  14. Method for synthesizing ultrafine powder materials

    DOEpatents

    Buss, Richard J.; Ho, Pauline

    1988-01-01

    A method for synthesizing ultrafine powder materials, for example, ceramic and metal powders, comprises admitting gaseous reactants from which the powder material is to be formed into a vacuum reaction chamber maintained at a pressure less than atmospheric and at a temperature less than about 400.degree. K. (127.degree.C.). The gaseous reactants are directed through a glow discharge provided in the vacuum reaction chamber to form the ultrafine powder material.

  15. Syntheses and studies of acetylenic polymers

    SciTech Connect

    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 (σ = 10-3 S/cm) after doping with AsF5. 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 x 103 to 5.3 x 103. Thermal stability of these was also investigated; char yields range from 56 to 83%. One of these polymers exhibits thermotropic liquid crystalline properties.

  16. Thermal Conductivity Measurement of Synthesized Mantle Minerals

    NASA Astrophysics Data System (ADS)

    Asimow, P. D.; Luo, S.; Mosenfelder, J. L.; Liu, W.; Staneff, G. D.; Ahrens, T. J.; Chen, G.

    2002-12-01

    Direct thermal conductivity (k) measurement of mantle minerals is crucial to constrain the thermal profile of the Earth as well as geodynamic studies of the mantle (e.g., to determine the Rayleigh number). We have embarked on systematic multi-anvil syntheses of dense polycrystalline specimens of mantle phases of adequate size and zero porosity for precise thermal conductivity measurements by the 3ω method (\\textit{Cahill and Pohl, Phys. Rev. B, 1987}) under elevated temperatures (T). Coesite and stishovite (see \\textit{Luo et al., GRL, 2002}) as well as majorite and wadsleyite have been synthesized; ringwoodite and perovskite are scheduled. Preliminary thermal conductivity measurements at ambient pressure on coesite (120 - 300 K, 9.53 Wm-1K-1 at 300 K) are consistent with prior room temperature data (\\textit{Yukutake & Shimada, PEPI, 1978}), while our stishovite data at 300 K appear to be low (1.96 Wm-1K-1). Efforts are being made to extend the measurement to higher temperatures (e.g., above Debye temperature Θ D), thus allowing determination of k(T) relationship (say, k~ T-n); success will depend on the decomposition kinetics of these metastable phases. The pressure dependence of k of these synthesized samples can also be measured (\\textit{e.g., Osako et al., HPMPS-6, 2002; Xu et al., EOS, 2001}). Recent thermal conductivity measurement on LiF and Al2O_3 from shock wave loading (\\textit{Holland & Ahrens, 1998}) is consistent with the modeling on MgO and Al2O_3 (\\textit{Manga & Jeanloz, JGR, 1997}) with classical theories. Thus, k values at modest pressures and T (say, above Θ D) would allow extrapolation of k to appropriate mantle conditions.

  17. Evaluating and synthesizing broadcasting satellite systems

    NASA Technical Reports Server (NTRS)

    Knouse, G. H.

    1974-01-01

    A system model and a computer program have been developed which are representative of broadcasting satellite systems employing several types of receiving terminals. The program provides a user-oriented tool for (1) evaluating performance/cost tradeoffs, (2) synthesizing minimum cost systems for a given set of system requirements, and (3) performing sensitivity analyses to identify critical user requirements, system parameters, and technology. The types of systems which can be evaluated are described, and the capabilities of the program are illustrated by means of several examples.

  18. Syntheses of Synthetic Hydrocarbons Via Alpha Olefins.

    DTIC Science & Technology

    1981-10-01

    Chem. Educ., 42, 502 (1965). 4. A. Priola, C. Corna , and S. Cesca, Macromolecules, 13, 1110 (1980). 5. R. F . Brown, Organic Chemistry, Wadsworth...AD-A110 380 GULF RESEARCH AND DEVELOPENT Co PITTSBURGH PA F /G T/A 1 SYNTHESES OF SYNTHETIC HYDROCARBONS VIA ALPHA OLEFINS.(U) OCT 81 B L CUPPLES, A...FOR THE COMMANDER F . D. CHERRY, Chief Nonmetallic Materials Division "If your address has changed, if you wish to be removed from our mailing list

  19. Biogenic synthesized nanoparticles and their applications

    NASA Astrophysics Data System (ADS)

    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.

  20. Squid Giant Axons Synthesize NF Proteins.

    PubMed

    Crispino, Marianna; Chun, Jong Tai; Giuditta, Antonio

    2017-05-02

    Squid giant axon has been an excellent model system for studying fundamental topics in neurobiology such as neuronal signaling. It has been also useful in addressing the questions of local protein synthesis in the axons. Incubation of isolated squid giant axons with [(35)S]methionine followed by immunoprecipitation with a rabbit antibody against all squid neurofilament (NF) proteins demonstrates the local synthesis of a major 180 kDa NF protein and of several NF proteins of lower molecular weights. Their identification as NF proteins is based on their absence in the preimmune precipitates. Immunoprecipitates washed with more stringent buffers confirmed these results. Our data are at variance with a recent study based on the same experimental procedure that failed to visualize the local synthesis of NF proteins by the giant axon and thereby suggested their exclusive derivation from nerve cell bodies (as reported by Gainer et al. in Cell Mol Neurobiol 37:475-486, 2017). By reviewing the pertinent literature, we confute the claims that mRNA translation is absent in mature axons because of a putative translation block and that most proteins of mature axons are synthesized in the surrounding glial cells. Given the intrinsic axonal capacity to synthesize proteins, we stress the glial derivation of axonal and presynaptic RNAs and the related proposal that these neuronal domains are endowed with largely independent gene expression systems (as reported by Giuditta et al. in Physiol Rev 88:515-555, 2008).

  1. Synthesizing new, high-temperature superconductors

    NASA Astrophysics Data System (ADS)

    Weaver, Claire; Aronson, Meigan

    2015-03-01

    Currently, there is no accepted theory behind type-II, high-temperature superconductors, but there is a distinct relationship between anti-ferromagnetism and superconductivity. Our research focuses on synthesizing new superconducting materials by observing the link between atomic structure and magnetic moments of anti-ferromagnetic compounds and attempting to reproduce the molecular physics of these known materials in new compounds. Consider the square-planar arrangement of the transition metal Fe in the Fe-pnictide superconductors of the ZrCuSiAs ``11 11'' and the ThCr2Si2 ``122'' structure types. We believe that the physics behind this superconductor, where Fe has d6 valence electrons, contributes to the superconducting state, not the presence of Fe itself. For this reason, we are synthesizing materials containing neighboring transition metals, like Mn and Co, combined with other elements in similar crystal lattice arrangements, having ionization properties that hopefully impose d6 valence electrons on the transition metals. This project was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internships Program (SULI).

  2. Biogenic synthesized nanoparticles and their applications

    SciTech Connect

    Singh, Abhijeet Sharma, Madan Mohan

    2016-05-06

    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 AgNO{sub 3} 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.

  3. Algorithm That Synthesizes Other Algorithms for Hashing

    NASA Technical Reports Server (NTRS)

    James, Mark

    2010-01-01

    An algorithm that includes a collection of several subalgorithms has been devised as a means of synthesizing still other algorithms (which could include computer code) that utilize hashing to determine whether an element (typically, a number or other datum) is a member of a set (typically, a list of numbers). Each subalgorithm synthesizes an algorithm (e.g., a block of code) that maps a static set of key hashes to a somewhat linear monotonically increasing sequence of integers. The goal in formulating this mapping is to cause the length of the sequence thus generated to be as close as practicable to the original length of the set and thus to minimize gaps between the elements. The advantage of the approach embodied in this algorithm is that it completely avoids the traditional approach of hash-key look-ups that involve either secondary hash generation and look-up or further searching of a hash table for a desired key in the event of collisions. This algorithm guarantees that it will never be necessary to perform a search or to generate a secondary key in order to determine whether an element is a member of a set. This algorithm further guarantees that any algorithm that it synthesizes can be executed in constant time. To enforce these guarantees, the subalgorithms are formulated to employ a set of techniques, each of which works very effectively covering a certain class of hash-key values. These subalgorithms are of two types, summarized as follows: Given a list of numbers, try to find one or more solutions in which, if each number is shifted to the right by a constant number of bits and then masked with a rotating mask that isolates a set of bits, a unique number is thereby generated. In a variant of the foregoing procedure, omit the masking. Try various combinations of shifting, masking, and/or offsets until the solutions are found. From the set of solutions, select the one that provides the greatest compression for the representation and is executable in the

  4. Simplification of Methods for PET Radiopharmaceutical Syntheses

    SciTech Connect

    Kilbourn, Michael, R.

    2011-12-27

    In an attempt to develop simplified methods for radiochemical synthesis of radiopharmaceuticals useful in Positron Emission Tomography (PET), current commercially available automated synthesis apparati were evaluated for use with solid phase synthesis, thin-film techniques, microwave-accelerated chemistry, and click chemistry approaches. Using combinations of these techniques, it was shown that these automated synthesis systems can be simply and effectively used to support the synthesis of a wide variety of carbon-11 and fluorine-18 labeled compounds, representing all of the major types of compounds synthesized and using all of the common radiochemical precursors available. These techniques are available for use to deliver clinically useful amounts of PET radiopharmaceuticals with chemical and radiochemical purities and high specific activities, suitable for human administration.

  5. Synthesizing Biomolecule-based Boolean Logic Gates

    PubMed Central

    Miyamoto, Takafumi; Razavi, Shiva; DeRose, Robert; Inoue, Takanari

    2012-01-01

    One fascinating recent avenue of study in the field of synthetic biology is the creation of biomolecule-based computers. The main components of a computing device consist of an arithmetic logic unit, the control unit, memory, and the input and output devices. Boolean logic gates are at the core of the operational machinery of these parts, hence to make biocomputers a reality, biomolecular logic gates become a necessity. Indeed, with the advent of more sophisticated biological tools, both nucleic acid- and protein-based logic systems have been generated. These devices function in the context of either test tubes or living cells and yield highly specific outputs given a set of inputs. In this review, we discuss various types of biomolecular logic gates that have been synthesized, with particular emphasis on recent developments that promise increased complexity of logic gate circuitry, improved computational speed, and potential clinical applications. PMID:23526588

  6. Methods for synthesizing metal oxide nanowires

    DOEpatents

    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.

  7. Syntheses and degradations of fluorinated heterocyclics

    NASA Technical Reports Server (NTRS)

    Paciorek, K. L.; Kratzer, R. H.; Kaufman, J.; Rosser, R. W.

    1975-01-01

    The relative stability of two ring systems, the triazine rings and 1,2,4-oxadiazoles, which offer potential crosslinks useful for curing perfluoroalkyl ether elastomers, has been investigated. Tris (perfluoro-n-heptyl)-s-triazine, the perfluoroether substituted-s-triazine, 1,4-bis/(5-perfluoro-n-heptyl)-1,2,4-oxadiazolyl/benzene, its perfluoroalkyl ether substituted analog, and 3,5-bis-(perfluoro-n-heptyl)-1,2,4-oxadiazole were synthesized and subjected to thermal and oxidative degradation at 235 and 325 C and to hydrolytic degradation at 235 C. The perfluoroalkyl ether substituted triazine and 3,5-bis(perfluoro-n-heptyl)-1,2,4-oxadiazole were found to be stable under all conditions investigated.

  8. Energy storage materials synthesized from ionic liquids.

    PubMed

    Gebresilassie Eshetu, Gebrekidan; Armand, Michel; Scrosati, Bruno; Passerini, Stefano

    2014-12-01

    The advent of ionic liquids (ILs) as eco-friendly and promising reaction media has opened new frontiers in the field of electrochemical energy storage. Beyond their use as electrolyte components in batteries and supercapacitors, ILs have unique properties that make them suitable as functional advanced materials, media for materials production, and components for preparing highly engineered functional products. Aiming at offering an in-depth review on the newly emerging IL-based green synthesis processes of energy storage materials, this Review provides an overview of the role of ILs in the synthesis of materials for batteries, supercapacitors, and green electrode processing. It is expected that this Review will assess the status quo of the research field and thereby stimulate new thoughts and ideas on the emerging challenges and opportunities of IL-based syntheses of energy materials.

  9. Syntheses and degradations of fluorinated heterocyclics

    NASA Technical Reports Server (NTRS)

    Paciorek, K. L.; Kratzer, R. H.; Kaufman, J.; Rosser, R. W.

    1975-01-01

    The relative stability of two ring systems, the triazine rings and 1,2,4-oxadiazoles, which offer potential crosslinks useful for curing perfluoroalkyl ether elastomers, has been investigated. Tris (perfluoro-n-heptyl)-s-triazine, the perfluoroether substituted-s-triazine, 1,4-bis/(5-perfluoro-n-heptyl)-1,2,4-oxadiazolyl/benzene, its perfluoroalkyl ether substituted analog, and 3,5-bis-(perfluoro-n-heptyl)-1,2,4-oxadiazole were synthesized and subjected to thermal and oxidative degradation at 235 and 325 C and to hydrolytic degradation at 235 C. The perfluoroalkyl ether substituted triazine and 3,5-bis(perfluoro-n-heptyl)-1,2,4-oxadiazole were found to be stable under all conditions investigated.

  10. Digital frequency synthesizer for radar astronomy

    NASA Technical Reports Server (NTRS)

    Sadr, R.; Satorius, E.; Robinett, L.; Olson, E.

    1990-01-01

    The digital frequency synthesizer (DFS) is an integral part of the programmable local oscillator (PLO) which is being developed for the NASA's Deep Space Network (DSN) and radar astronomy. Here, the theory of operation and the design of the DFS are discussed, and the design parameters in application for the Goldstone Solar System Radar (GSSR) are specified. The spectral purity of the DFS is evaluated by analytically evaluating the output spectrum of the DFS. A novel architecture is proposed for the design of the DFS with a frequency resolution of 1/2(exp 48) of the clock frequency (0.35 mu Hz at 100 MHz), a phase resolution of 0.0056 degrees (16 bits), and a frequency spur attenuation of -96 dBc.

  11. Intermetallic Nanocrystals: Syntheses and Catalytic Applications.

    PubMed

    Yan, Yucong; Du, Jingshan S; Gilroy, Kyle D; Yang, Deren; Xia, Younan; Zhang, Hui

    2017-02-24

    At the forefront of nanochemistry, there exists a research endeavor centered around intermetallic nanocrystals, which are unique in terms of long-range atomic ordering, well-defined stoichiometry, and controlled crystal structure. In contrast to alloy nanocrystals with no elemental ordering, it is challenging to synthesize intermetallic nanocrystals with a tight control over their size and shape. Here, recent progress in the synthesis of intermetallic nanocrystals with controllable sizes and well-defined shapes is highlighted. A simple analysis and some insights key to the selection of experimental conditions for generating intermetallic nanocrystals are presented, followed by examples to highlight the viable use of intermetallic nanocrystals as electrocatalysts or catalysts for various reactions, with a focus on the enhanced performance relative to their alloy counterparts that lack elemental ordering. Within the conclusion, perspectives on future developments in the context of synthetic control, structure-property relationships, and applications are discussed.

  12. Synthesizing biomolecule-based Boolean logic gates.

    PubMed

    Miyamoto, Takafumi; Razavi, Shiva; DeRose, Robert; Inoue, Takanari

    2013-02-15

    One fascinating recent avenue of study in the field of synthetic biology is the creation of biomolecule-based computers. The main components of a computing device consist of an arithmetic logic unit, the control unit, memory, and the input and output devices. Boolean logic gates are at the core of the operational machinery of these parts, and hence to make biocomputers a reality, biomolecular logic gates become a necessity. Indeed, with the advent of more sophisticated biological tools, both nucleic acid- and protein-based logic systems have been generated. These devices function in the context of either test tubes or living cells and yield highly specific outputs given a set of inputs. In this review, we discuss various types of biomolecular logic gates that have been synthesized, with particular emphasis on recent developments that promise increased complexity of logic gate circuitry, improved computational speed, and potential clinical applications.

  13. Molecular scale electronics: syntheses and testing

    NASA Astrophysics Data System (ADS)

    Reinerth, William A.; Jones, LeRoy, II; Burgin, Timothy P.; Zhou, Chong-wu; Muller, C. J.; Deshpande, M. R.; Reed, Mark A.; Tour, James M.

    1998-09-01

    This paper describes four significant breakthroughs in the syntheses and testing of molecular scale electronic devices. The 16-mer of oligo(2-dodecylphenylene ethynylene) was prepared on Merrifields resin using the iterative divergent/convergent approach which significantly streamlines the preparation of this molecular scale wire. The formation of self-assembled monolayers and multilayers on gold surfaces of rigid rod conjugated oligomers that have thiol, 0957-4484/9/3/016/img11-dithiol, thioacetyl, or 0957-4484/9/3/016/img11-dithioacetyl end groups have been studied. The direct observation of charge transport through molecules of benzene-1, 4-dithiol, which have been self-assembled onto two facing gold electrodes, has been achieved. Finally, we report initial studies into what effect varying the molecular alligator clip has on the molecule scale wire's conductivity.

  14. Method and apparatus for synthesizing hydrocarbons

    DOEpatents

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

    1985-04-16

    A method and apparatus for synthesizing a mixture of aliphatic alcohols 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 optionally includes Na ions present as substitutional cations in an amount of about 5 to 10 atom %. At a temperature of about 570 to 630/sup 0/K, and at pressures of about 20 to 50 atm, methanol and isobutanol are the predominant products and are produced in amounts of about 90 wt % of the total hydrocarbon mixture. 6 figs.

  15. Method and apparatus for synthesizing hydrocarbons

    DOEpatents

    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.

  16. Synthesizing plant phenological indicators from multispecies datasets

    NASA Astrophysics Data System (ADS)

    Rutishauser, This; Peñuelas, Josep; Filella, Iolanda; Gehrig, Regula; Scherrer, Simon C.; Röthlisberger, Christian

    2014-05-01

    Changes in the seasonality of life cycles of plants from phenological observations are traditionally analysed at the species level. Trends and correlations with main environmental driving variables show a coherent picture across the globe. The question arises whether there is an integrated phenological signal across species that describes common interannual variability. Is there a way to express synthetic phenological indicators from multispecies datasets that serve decision makers as usefull tools? Can these indicators be derived in such a robust way that systematic updates yield necessary information for adaptation measures? We address these questions by analysing multi-species phenological data sets with leaf-unfolding and flowering observations from 30 sites across Europe between 40° and 63°N including data from PEP725, the Swiss Plant Phenological Observation Network and one legacy data set. Starting in 1951 the data sets were synthesized by multivariate analysis (Principal Component Analysis). The representativeness of the site specific indicator was tested against subsets including only leaf-unfolding or flowering phases, and by a comparison with a 50% random sample of the available phenophases for 500 time steps. Results show that a synthetic indicators explains up to 79% of the variance at each site - usually 40-50% or more. Robust linear trends over the common period 1971-2000 indicate an overall change of the indicator of -0.32 days/year with lower uncertainty than previous studies. Advances were more pronounced in southern and northern Europe. The indicator-based analysis provides a promising tool for synthesizing site-based plant phenological records and is a companion to, and validating data for, an increasing number of phenological measurements derived from phenological models and satellite sensors.

  17. Syntheses and Structure Determinations of Calcium Thiolates.

    PubMed

    Chadwick, Scott; Englich, Ulrich; Noll, Bruce; Ruhlandt-Senge, Karin

    1998-09-07

    The exploration of synthetic methodologies toward heavy alkaline-earth chalcogenolates resulted in the preparation and structural characterization of a family of calcium thiolates, including [Ca(SC(6)F(5))(2)(py)(4)], 1 (py = pyridine), the separated ion-triple [Ca(18-crown-6)(NH(3))(3))][SMes](2).2THF, 2 (Mes = 2,4,6-tBu(3)C(6)H(2)), and the contact triple [Ca(18-crown-6)(SMes)(2)].THF, 3. Compound 1 was prepared by treating [Ca(N(SiMe(3))(2))(2)](2) with 4 equiv of HSC(6)F(5) under addition of pyridine. The thiolates 2 and 3 were synthesized by treatment of calcium metal dissolved in dry, liquid NH(3) under addition of 2 equiv of HSMes and crown ether or, alternatively, by the reduction of MesSSMes with calcium metal in dry, liquid ammonia. We also report two reaction products isolated during attempted calcium thiolate syntheses: [CaBr(4)(THF)(2)(&mgr;(2)-Li)(2)(THF)(4)], 4, isolated as the product of a salt elimination reaction between CaBr(2) and 2 equiv of [Li(THF)(n)()S-2,4,6-(i)()Pr(3)C(6)H(2)](m)(). [(NH(4))(py)(SC(6)F(5))], 5, was obtained as the sole product in the reaction of metallic calcium with HSC(6)F(5) in liquid ammonia under addition of pyridine. All compounds were characterized by single-crystal X-ray crystallography in addition to IR and NMR spectroscopy.

  18. Localization of ANP-synthesizing cells in rat stomach

    PubMed Central

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

    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. PMID:17007021

  19. Why can't vertebrates synthesize trehalose?

    PubMed

    Argüelles, Juan-Carlos

    2014-10-01

    The non-reducing disaccharide trehalose is a singular molecule, which has been strictly conserved throughout evolution in prokaryotes (bacteria and archaea), lower eukaryotes, plants, and invertebrates, but is absent in vertebrates and-more specifically-in mammals. There are notable differences regarding the pivotal roles played by trehalose among distantly related organisms as well as in the specific metabolic pathways of trehalose biosynthesis and/or hydrolysis, and the regulatory mechanisms that control trehalose expression genes and enzymatic activities. The success of trehalose compared with that of other structurally related molecules is attributed to its exclusive set of physical properties, which account for its physiological roles and have also promoted important biotechnological applications. However, an intriguing question still remains: why are vertebrates in general, and mammals in particular, unable (or have lost the capacity) to synthesize trehalose? The search for annotated genomes of vertebrates reveals the absence of any functional trehalose synthase gene. Indeed, this is also true for the human genome, which contains, however, two genes encoding for isoforms of the hydrolytic activity (trehalase). Although we still lack a convincing answer, this striking difference might reflect the divergent evolutionary lineages followed by invertebrates and vertebrates. Alternatively, some clinical data point to trehalose as a toxic molecule when stored inside the human body.

  20. Multistep sintering to synthesize fast lithium garnets

    NASA Astrophysics Data System (ADS)

    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.

  1. Copper nanocoils synthesized through solvothermal method

    NASA Astrophysics Data System (ADS)

    Liu, Yanjuan; Liu, Xiaowei; Zhan, Yongjie; Fan, Haiming; Lu, Yang

    2015-11-01

    Recently helical nanostructures such as nanosprings and nanocoils have drawn great interests in nanotechnology, due to their unique morphologies and physical properties, and they may be potential building blocks in sorts of electromechanical, magnetic, photoelectronic and plasmonic devices at micro/nanoscales. In this report, multi-turns copper nanocoils were synthesized through a modified solvothermal method, in which the mixture of water and N-methyl-2-pyrrolidone (NMP) were selected as reaction medium and copolymer poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP/VA 64E) as reductant. In the liquid solution, nanosprings could be formed from relaxed nanocoils and demonstrated high elasticity. These nanocoils and nanosprings are of single crystalline structure, with the characteristics wire diameters ranging from tens to a few hundreds of nanometers and the ring/coil diameters mostly ~10-35 microns. Their growth and deformation mechanisms were then investigated and discussed along with that of previously reported single-turn copper nanorings. This work could be of importance for researchers working on synthesis and applications of novel 1-D helical nanomaterials and their functional devices.

  2. Mechanochemically Driven Syntheses of Boride Nanomaterials

    NASA Astrophysics Data System (ADS)

    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.

  3. A technique for synthesizing metal tritide standards

    SciTech Connect

    Bach, H. T.; Allen, T. H.; Hill, D. D.; Martinez, P. T.; Schwarz, R. B.; Paglieri, S. N.; Wermer, J. R.

    2008-07-15

    Before surplus plutonium pits can be decommissioned and converted into metal oxides to be used as reactor fuels, residual tritium must be reduced to an acceptable level. We have developed two analytical methods involving melting and acid dissolution, combined with liquid scintillation counting as a quantitative and sensitive technique for measuring residual tritium in Pu metal. The detection limit, linearity, and reproducibility of these analytical methods must be validated with a series of metal tritide standards. Since there are no commercially available metal tritide standards, we have developed a technique for their synthesis. The synthesis of these low-level metal tritide standards is accomplished by charging cerium powder with a known amount of tritium to form a master cerium tritide alloy and then by aliquoting from this master alloy and diluting with pure cerium powder to form a series of standards with different tritium concentrations. The major difficulty in synthesizing these standards is that the samples contain extremely low levels of tritium, which span over three decades of concentrations. The synthesis technique and initial data obtained for cerium hydride samples will be presented. (authors)

  4. Multilayer graphane synthesized under high hydrogen pressure

    DOE PAGES

    Antonov, V. E.; Bashkin, I. O.; Bazhenov, A. V.; ...

    2015-12-19

    A new hydrocarbon – hydrographite – with the composition close to CH is shown to form from graphite and gaseous hydrogen at pressures above 2 GPa and temperatures from 450 to 700 °C. Hydrographite is a black solid thermally stable under ambient conditions. When heated in vacuum, it decomposes into graphite and molecular hydrogen at temperatures from 500 to 650 °C. Powder X-ray diffraction characterizes hydrographite as a multilayer “graphane II” phase predicted by ab initio calculations [Wen X-D et al. PNAS 2011; 108:6833] and consisting of graphane sheets in the chair conformation stacked along the hexagonal c axis inmore » the -ABAB- sequence. The crystal structure of the synthesized phase belongs to the P63mc space group. Moreover, the unit cell parameters are a = 2.53(1) Å and c = 9.54(1) Å and therefore exceed the corresponding parameters of graphite by 2.4(2)% and 42.0(3)%. Stretching vibrations of C–H groups on the surface of the hydrographite particles are examined by infrared spectroscopy.« less

  5. Multilayer graphane synthesized under high hydrogen pressure

    SciTech Connect

    Antonov, V. E.; Bashkin, I. O.; Bazhenov, A. V.; Bulychev, B. M.; Fedotov, V. K.; Fursova, T. N.; Kolesnikov, A. I.; Kulakov, V. I.; Lukashev, R. V.; Matveev, D. V.; Sakharov, M. K.; Shulga, Y. M.

    2015-12-19

    A new hydrocarbon – hydrographite – with the composition close to CH is shown to form from graphite and gaseous hydrogen at pressures above 2 GPa and temperatures from 450 to 700 °C. Hydrographite is a black solid thermally stable under ambient conditions. When heated in vacuum, it decomposes into graphite and molecular hydrogen at temperatures from 500 to 650 °C. Powder X-ray diffraction characterizes hydrographite as a multilayer “graphane II” phase predicted by ab initio calculations [Wen X-D et al. PNAS 2011; 108:6833] and consisting of graphane sheets in the chair conformation stacked along the hexagonal c axis in the -ABAB- sequence. The crystal structure of the synthesized phase belongs to the P63mc space group. Moreover, the unit cell parameters are a = 2.53(1) Å and c = 9.54(1) Å and therefore exceed the corresponding parameters of graphite by 2.4(2)% and 42.0(3)%. Stretching vibrations of C–H groups on the surface of the hydrographite particles are examined by infrared spectroscopy.

  6. Copper nanocoils synthesized through solvothermal method.

    PubMed

    Liu, Yanjuan; Liu, Xiaowei; Zhan, Yongjie; Fan, Haiming; Lu, Yang

    2015-11-26

    Recently helical nanostructures such as nanosprings and nanocoils have drawn great interests in nanotechnology, due to their unique morphologies and physical properties, and they may be potential building blocks in sorts of electromechanical, magnetic, photoelectronic and plasmonic devices at micro/nanoscales. In this report, multi-turns copper nanocoils were synthesized through a modified solvothermal method, in which the mixture of water and N-methyl-2-pyrrolidone (NMP) were selected as reaction medium and copolymer poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP/VA 64E) as reductant. In the liquid solution, nanosprings could be formed from relaxed nanocoils and demonstrated high elasticity. These nanocoils and nanosprings are of single crystalline structure, with the characteristics wire diameters ranging from tens to a few hundreds of nanometers and the ring/coil diameters mostly ~10-35 microns. Their growth and deformation mechanisms were then investigated and discussed along with that of previously reported single-turn copper nanorings. This work could be of importance for researchers working on synthesis and applications of novel 1-D helical nanomaterials and their functional devices.

  7. Total Syntheses of (+)-Tedanolide and (+)-13-Deoxytedanolide

    PubMed Central

    Dunetz, Joshua R.; Julian, Lisa D.; Newcom, Jason S.; Roush, William R.

    2009-01-01

    Convergent total syntheses of the potent cytotoxins (+)-tedanolide (1) and (+)-13-deoxytedanolide (2) are described. The carbon framework of these compounds was assembled via a stereoselective aldol reaction that unifies the C(1)–C(12) ketone fragment 5 with a C(13)–C(23) aldehyde fragment 6 (for 13-deoxytedanolide) or 52 (for tedanolide). Multiple obstacles were encountered en route to (+)-1 and (+)-2 that required very careful selection and orchestration of the stereochemistry and functionality of key intermediates. Chief among these issues was the remarkable stability and lack of reactivity of hemiketals 33b and 34 that prevented the tedanolide synthesis from being completed from aldol 4. Key to the successful completion of the tedanolide synthesis was the observation that the 13-deoxy hemiketal 36 could be oxidized to C(11,15)-diketone 38 en route to 13-deoxytedanolide. This led to the decision to pursue the tedanolide synthesis via C(15)-(S)-epimers, since this stereochemical change would destabilize the hemiketal that plagued the attempted synthesis of tedanolide via C(15)-(R) intermediates. However, use of C(15)-(S) configured intermediates required that the side chain epoxide be introduced very late in the synthesis, owing to the ease with which the C(15)-(S)-OH cyclized onto the epoxide of intermediate 50. PMID:18980317

  8. Chemically synthesized FePt nanoclusters

    NASA Astrophysics Data System (ADS)

    Velasco, Victor; Abel, Frank; Hu, Xiaocao; Crespo, Patricia; Hadjipanayis, George

    2014-03-01

    FePt nanoparticles (NPs) are being widely investigated due to their high potential applications in magnetic recording media and biomedicine. These NPs are expected to be ideal candidates due to their excellent magnetic properties, such as high K and high Ms together with a high chemical stability. In this work, the FePt NPs have been synthesized by chemical routes according to the method reported by M. Chen et al.[2] At high temperature, surfactants together with iron pentacarbonyl are added to the solution and thermally decomposed. By controlling the injection temperature and the heating rate, we have been able to obtain homogeneous spherical clusters with an average size of 38 +/- 10 nm formed by 5 nm-FePt NPs. These clusters are found to be superparamagnetic above Tb of 55 K whereas at 5 K exhibit a coercive field of 1.2 kOe. Furthermore, these NPs seem to be highly stable in water after replacing the surfactants by TMAOH. These clusters appear to be good candidates for MRI and hyperthermia applications. This work was supported by NSF DMR-0302544.

  9. Oligodendrocyte Precursor Cells Synthesize Neuromodulatory Factors

    PubMed Central

    Sakry, Dominik; Yigit, Hatice; Dimou, Leda; Trotter, Jacqueline

    2015-01-01

    NG2 protein-expressing oligodendrocyte progenitor cells (OPC) are a persisting and major glial cell population in the adult mammalian brain. Direct synaptic innervation of OPC by neurons throughout the brain together with their ability to sense neuronal network activity raises the question of additional physiological roles of OPC, supplementary to generating myelinating oligodendrocytes. In this study we investigated whether OPC express neuromodulatory factors, typically synthesized by other CNS cell types. Our results show that OPC express two well-characterized neuromodulatory proteins: Prostaglandin D2 synthase (PTGDS) and neuronal Pentraxin 2 (Nptx2/Narp). Expression levels of the enzyme PTGDS are influenced in cultured OPC by the NG2 intracellular region which can be released by cleavage and localizes to glial nuclei upon transfection. Furthermore PTGDS mRNA levels are reduced in OPC from NG2-KO mouse brain compared to WT cells after isolation by cell sorting and direct analysis. These results show that OPC can contribute to the expression of these proteins within the CNS and suggest PTGDS expression as a downstream target of NG2 signaling. PMID:25966014

  10. A new method to synthesize creatine derivatives.

    PubMed

    Garbati, Patrizia; Salis, Annalisa; Adriano, Enrico; Galatini, Andrea; Damonte, Gianluca; Balestrino, Maurizio; Millo, Enrico

    2013-10-01

    Creatine is an amino acid that has a pivotal role in energy metabolism of cells. Creatine acts as an "ATP shuttle", carrying ATP to the sites where it is utilized, through its reversible phosphorylation by creatine kinase. Moreover, the creatine-phosphocreatine system delays ATP depletion during anoxia or ischemia, thus exerting a neuroprotective role during those pathological conditions. Thus, its administration has been advocated as a treatment or prevention of several conditions involving the central nervous system. However, creatine crosses poorly the blood-brain barrier and the cell plasma membrane, thus its administration has but a limited effect. The use of more lipophilic creatine derivatives has thus been suggested. However, such a synthesis is complicated by the intrinsic characteristics of the creatine molecule that hardly reacts with other molecules and easily cyclizes to creatinine. We obtained amide derivatives from creatine starting from a new protected creatine molecule synthesized by us, the so-called (Boc)2-creatine. We used a temporary protection only on the creatine guanidine group while allowing a good reactivity on the carboxylic group. This temporary protection ensured efficient creatine dissolution in organic solvents and offered simultaneous protection of creatine toward intramolecular cyclization to creatinine. In this manner, it was possible to selectively conjugate molecules on the carboxylic group. The creatine guanidine group was easily released from the protection at the end of the reaction, thus obtaining the desired creatine derivative.

  11. [Femicides in ethnic and racialized groups: syntheses].

    PubMed

    Meneghel, Stela Nazareth; Lerma, Betty Ruth Lozano

    2017-01-01

    The text entitled "Femicides in ethnic and racialized groups: syntheses" presents some of the discussions that took place during a seminar on this topic in Buenaventura. Buenaventura is the main Colombian port on the Pacific, a region rich in minerals and a corridor for the movement of goods, which makes it a strategic territory and a center for disputes. At the seminar, the social and political determinants of femicide were discussed, understanding it as a tactic of waging war against women. The forum provided a space for academic discussion, but also for grievances over inter-personal violence, the manifestation of feelings and the elaboration of pain and grief through the medium of art. We believe that the dissemination of this experience to the Brazilian public, in a country with ethnic, social and racial vulnerability similar to that in Colombia, will be of value to social and health workers. The scope of this paper is therefore to provide the opinion of its authors on the determinants of femicides and on actions to tackle them, in addition to a synthesis of the discussions and debates that permeated the event.

  12. Copper nanocoils synthesized through solvothermal method

    PubMed Central

    Liu, Yanjuan; Liu, Xiaowei; Zhan, Yongjie; Fan, Haiming; Lu, Yang

    2015-01-01

    Recently helical nanostructures such as nanosprings and nanocoils have drawn great interests in nanotechnology, due to their unique morphologies and physical properties, and they may be potential building blocks in sorts of electromechanical, magnetic, photoelectronic and plasmonic devices at micro/nanoscales. In this report, multi-turns copper nanocoils were synthesized through a modified solvothermal method, in which the mixture of water and N-methyl-2-pyrrolidone (NMP) were selected as reaction medium and copolymer poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP/VA 64E) as reductant. In the liquid solution, nanosprings could be formed from relaxed nanocoils and demonstrated high elasticity. These nanocoils and nanosprings are of single crystalline structure, with the characteristics wire diameters ranging from tens to a few hundreds of nanometers and the ring/coil diameters mostly ~10–35 microns. Their growth and deformation mechanisms were then investigated and discussed along with that of previously reported single-turn copper nanorings. This work could be of importance for researchers working on synthesis and applications of novel 1-D helical nanomaterials and their functional devices. PMID:26607386

  13. Endothelial cells synthesize and process apolipoprotein B.

    PubMed

    Sivaram, P; Vanni-Reyes, T; Goldberg, I J

    1996-06-21

    We reported previously that a 116-kDa lipoprotein lipase (LPL)-binding protein from endothelial cells has sequence homology to the amino-terminal region of apolipoprotein (apo) B. We now tested whether endothelial cells synthesize apoB mRNA and protein. Primers were designed to the human apoB cDNA sequence and reverse transcription polymerase chain reaction was performed using total RNA isolated from bovine and human endothelial cells. With primers to the 5' region of the apoB mRNA (amino-terminal region of apoB protein) expected size PCR products were generated from both bovine and human endothelial cells as well as from mouse liver RNA, which was used as a control. Primers designed to the 3' region of apoB mRNA generated PCR products from human endothelial cells and HepG2 cells but not from bovine or mouse cells. These data suggest that endothelial cells contain full-length apoB mRNA and that the 5' or the amino-terminal region of apoB is highly conserved from mouse to human. This was confirmed by direct sequencing of the mouse and bovine PCR products. To test whether apoB protein was produced, bovine endothelial cell proteins were metabolically labeled with [35S]methionine/cysteine or [3H]leucine and immunoprecipitated with anti-human apoB antibodies. Using extracts from cells labeled for 1 h, monoclonal antibody 47, directed to the low density lipoprotein receptor binding region of apoB, precipitated a protein of approximate molecular mass 550,000, the size of full-length apoB. Immunoprecipitation of the 550-kDa protein was abolished in the presence of added unlabeled low density lipoprotein. From cells labeled for 16 h, a 116-kDa protein was immunoprecipitated by polyclonal anti-apoB antibodies. This protein was partly released from cells by heparin treatment. Pulse-chase analysis showed that the 116-kDa fragment appeared at the same time as the full-length apoB began disappearing. The immunoprecipitated 116-kDa fragment also bound labeled LPL on ligand blot

  14. Synthesized Spectra of Optically Thin Emission Lines

    NASA Astrophysics Data System (ADS)

    Olluri, K.; Gudiksen, B. V.; Hansteen, V. H.; De Pontieu, B.

    2015-03-01

    In recent years realistic 3D numerical models of the solar atmosphere have become available. The models attempt to recreate the solar atmosphere and mimic observations in the best way, in order to make it possible to couple complicated observations with physical properties such as the temperatures, densities, velocities, and magnetic fields. We here present a study of synthetic spectra created using the Bifrost code in order to assess how well they fit with previously taken solar data. A study of the synthetic intensity, nonthermal line widths, Doppler shifts, and correlations between any two of these three components of the spectra first assuming statistical equilibrium is made, followed by a report on some of the effects nonequilibrium ionization will have on the synthesized spectra. We find that the synthetic intensities compare well with the observations. The synthetic observations depend on the assumed resolution and point-spread function (PSF) of the instrument, and we find a large effect on the results, especially for intensity and nonthermal line width. The Doppler shifts produce the reported persistent redshifts for the transition region (TR) lines and blueshifts for the upper TR and corona lines. The nonthermal line widths reproduce the well-known turnoff point around (2-3) × 105 K, but with much lower values than those observed. The nonthermal line widths tend to increase with decreasing assumed instrumental resolution, also when nonequilibrium ionization is included. Correlations between the nonthermal line width of any two TR line studies as reported by Chae et al. are reproduced, while the correlations of intensity to line width are reproduced only after applying a PSF to the data. Doppler shift correlations reported by Doschek for the TR lines and correlations of Doppler shift to nonthermal line width of the Fe xii 19.5 line reported by Doschek et al. are reproduced.

  15. Human brain glial cells synthesize thrombospondin.

    PubMed Central

    Asch, A S; Leung, L L; Shapiro, J; Nachman, R L

    1986-01-01

    Thrombospondin, a 450-kDa multinodular glycoprotein with lectin-type activity, is found in human platelets, endothelial cells, fibroblasts, smooth muscle cells, monocytes, and granular pneumocytes. Thrombospondin interacts with heparin, fibrinogen, fibronectin, collagen, histidine-rich glycoprotein, and plasminogen. Recently, thrombospondin synthesis by smooth muscle cells has been reported to be augmented by platelet-derived growth factor. We present evidence that thrombospondin is present within and synthesized by astrocytic neuroglial cells. Heparin-Sepharose affinity chromatography of material derived from a human brain homogenate yielded a protein that, when reduced, had an apparent size of 180 kDa and comigrated with reduced platelet thrombospondin on NaDodSO4/PAGE. Immunoblot analysis with monospecific anti-thrombospondin confirmed the presence of immunoreactive thrombospondin. Indirect immunofluorescence of cultured human glial cells indicated the presence of thrombospondin. Metabolic labeling of glial cell cultures with [35S]methionine followed by immunoprecipitation with monospecific anti-thrombospondin revealed synthesis of a 180-kDa polypeptide that comigrated with platelet thrombospondin on NaDodSO4/PAGE. Cultured human glial cells were incubated for 48 hr in serum-free medium with purified platelet-derived growth factor at concentrations up to 50 ng/ml. Aliquots taken at intervals were analyzed by a quantitative double-antibody ELISA. The growth factor stimulated the release of thrombospondin into the culture medium by as much as 10-fold over control cultures. The presence of thrombospondin within glial cells of the central nervous system and the augmentation of its synthesis by platelet-derived growth factor suggest that thrombospondin may play an important role in regulating cell-cell and cell-matrix interactions during periods of cell division and growth. Images PMID:2939460

  16. Syntheses and electronic structures of decamethylmetallocenes

    SciTech Connect

    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.

  17. Production of bacterial cellulose from alternate feedstocks

    SciTech Connect

    D. N. Thompson; M. A. Hamilton

    2000-05-07

    Production of bacterial cellulose by Acetobacter xylinum ATCC 10821 and 23770 in static cultures was tested from unamended food process effluents. Effluents included low- and high-solids potato effluents (LS and HS), cheese whey permeate (CW), and sugar beet raffinate (CSB). Strain 23770 produced 10% less cellulose from glucose than did 10821, and diverted more glucose to gluconate. Unamended HS, CW, and CSB were unsuitable for cellulose production by either strain, while LS was unsuitable for production by 10821. However, 23770 produced 17% more cellulose from LS than from glucose, indicating unamended LS could serve as a feedstock for bacterial cellulose.

  18. Production of Bacterial Cellulose from Alternate Feedstocks

    SciTech Connect

    Thompson, David Neil; Hamilton, Melinda Ann

    2000-05-01

    Production of bacterial cellulose by Acetobacter xylinum ATCC 10821 and 23770 in static cultures was tested from unamended food process effluents. Effluents included low- and high-solids potato effluents (LS & HS), cheese whey permeate (CW), and sugar beet raffinate (CSB). Strain 23770 produced 10% less cellulose from glucose than did 10821, and diverted more glucose to gluconate. Unamended HS, CW, and CSB were unsuitable for cellulose production by either strain, while LS was unsuitable for production by 10821. However, 23770 produced 17% more cellulose from LS than from glucose, indicating unamended LS could serve as a feedstock for bacterial cellulose.

  19. Synthesizing Smart Polymeric and Composite Materials

    NASA Astrophysics Data System (ADS)

    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

  20. Cellulose biosynthesis and function in bacteria.

    PubMed Central

    Ross, P; Mayer, R; Benziman, M

    1991-01-01

    The current model of cellulose biogenesis in plants, as well as bacteria, holds that the membranous cellulose synthase complex polymerizes glucose moieties from UDP-Glc into beta-1,4-glucan chains which give rise to rigid crystalline fibrils upon extrusion at the outer surface of the cell. The distinct arrangement and degree of association of the polymerizing enzyme units presumably govern extracellular chain assembly in addition to the pattern and width of cellulose fibril deposition. Most evident for Acetobacter xylinum, polymerization and assembly appear to be tightly coupled. To date, only bacteria have been effectively studied at the biochemical and genetic levels. In A. xylinum, the cellulose synthase, composed of at least two structurally similar but functionally distinct subunits, is subject to a multicomponent regulatory system. Regulation is based on the novel nucleotide cyclic diguanylic acid, a positive allosteric effector, and the regulatory enzymes maintaining its intracellular turnover: diguanylate cyclase and Ca2(+)-sensitive bis-(3',5')-cyclic diguanylic acid (c-di-GMP) phosphodiesterase. Four genes have been isolated from A. xylinum which constitute the operon for cellulose synthesis. The second gene encodes the catalytic subunit of cellulose synthase; the functions of the other three gene products are still unknown. Exclusively an extracellular product, bacterial cellulose appears to fulfill diverse biological roles within the natural habitat, conferring mechanical, chemical, and physiological protection in A. xylinum and Sarcina ventriculi or facilitating cell adhesion during symbiotic or infectious interactions in Rhizobium and Agrobacterium species. A. xylinum is proving to be most amenable for industrial purposes, allowing the unique features of bacterial cellulose to be exploited for novel product applications. Images PMID:2030672

  1. The Electronic Music Synthesizer and the Physics of Music

    ERIC Educational Resources Information Center

    Hartmann, W. M.

    1975-01-01

    Describes the principal modules of analog electronic music synthesizers and discusses some ways that a synthesizer has been used in demonstrations, in psychophysical experiments, and in an undergraduate laboratory course in the physics of music and acoustics. Considers the synthesis of both steady and transitory auditory phenomena. (Author/MLH)

  2. Chemical Strategies for Template Syntheses of Composite Micro and Nanostructures.

    DTIC Science & Technology

    1997-05-02

    CHEMICAL STRATEGIES FOR TEMPLATE SYNTHESES OF COMPOSITE MICRO AND NANOSTRUCTURES Veronica M. Cepak, John C. Hulteen, Guangli Che, Kshama B. Jirage...for the first time, template-based syntheses of composite micro and nanostructures in which an outer tubule composed of one material encapsulates...ropolymerizations. The template method for preparing nanomaterials entails synthesis of monodisperse tubular and fibrillar nanostructures within the

  3. The Electronic Music Synthesizer and the Physics of Music

    ERIC Educational Resources Information Center

    Hartmann, W. M.

    1975-01-01

    Describes the principal modules of analog electronic music synthesizers and discusses some ways that a synthesizer has been used in demonstrations, in psychophysical experiments, and in an undergraduate laboratory course in the physics of music and acoustics. Considers the synthesis of both steady and transitory auditory phenomena. (Author/MLH)

  4. Perturbation Measurements on the Degree of Naturalness of Synthesized Vowels.

    PubMed

    Yamasaki, Rosiane; Montagnoli, Arlindo; Murano, Emi Z; Gebrim, Eloisa; Hachiya, Adriana; Lopes da Silva, Jorge Vicente; Behlau, Mara; Tsuji, Domingos

    2017-05-01

    To determine the impact of jitter and shimmer on the degree of naturalness perception of synthesized vowels produced by acoustical simulation with glottal pulses (GP) and with solid model of the vocal tract (SMVT). Prospective study. Synthesized vowels were produced in three steps: 1. Eighty GP were developed (20 with jitter, 20 with shimmer, 20 with jitter+shimmer, 20 without perturbation); 2. A SMVT was produced based on magnetic resonance imaging (MRI) from a woman during phonation-/ε/ and using rapid prototyping technology; 3. Acoustic simulations were performed to obtain eighty synthesized vowels-/ε /. Two experiments were performed. First Experiment: three judges rated 120 vowels (20 humans+80 synthesized+20% repetition) as "human" or "synthesized". Second Experiment: twenty PowerPoint slide sequences were created. Each slide had 4 synthesized vowels produced with the four perturbation condition. Evaluators were asked to rate the vowels from the most natural to the most artificial. First Experiment: all the human vowels were classified as human; 27 out of eighty synthesized vowels were rated as human, 15 of those were produced with jitter+shimmer, 10 with jitter, 2 without perturbation and none with shimmer. Second Experiment: Vowels produced with jitter+shimmer were considered as the most natural. Vowels with shimmer and without perturbation were considered as the most artificial. The association of jitter and shimmer increased the degree of naturalness of synthesized vowels. Acoustic simulations performed with GP and using SMVT demonstrated a possible method to test the effect of the perturbation measurements on synthesized voices. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

  5. Method for Synthesizing Extremeley High Temperature Melting Materials

    DOEpatents

    Saboungi, Marie-Louise and Glorieux, Benoit

    2005-11-22

    The invention relates to a method of synthesizing high-temperature melting materials. More specifically the invention relates to a containerless method of synthesizing very high temperature melting materials such as borides, carbides and transition-metal, lanthanide and actinide oxides, using an Aerodynamic Levitator and a laser. The object of the invention is to provide a method for synthesizing extremely high-temperature melting materials that are otherwise difficult to produce, without the use of containers, allowing the manipulation of the phase (amorphous/crystalline/metastable) and permitting changes of the environment such as different gaseous compositions.

  6. Method For Synthesizing Extremely High-Temperature Melting Materials

    DOEpatents

    Saboungi, Marie-Louise; Glorieux, Benoit

    2005-11-22

    The invention relates to a method of synthesizing high-temperature melting materials. More specifically the invention relates to a containerless method of synthesizing very high temperature melting materials such as borides, carbides and transition-metal, lanthanide and actinide oxides, using an Aerodynamic Levitator and a laser. The object of the invention is to provide a method for synthesizing extremely high-temperature melting materials that are otherwise difficult to produce, without the use of containers, allowing the manipulation of the phase (amorphous/crystalline/metastable) and permitting changes of the environment such as different gaseous compositions.

  7. Method for synthesizing extremely high-temperature melting materials

    DOEpatents

    Saboungi, Marie-Louise; Glorieux, Benoit

    2007-11-06

    The invention relates to a method of synthesizing high-temperature melting materials. More specifically the invention relates to a containerless method of synthesizing very high temperature melting materials such as carbides and transition-metal, lanthanide and actinide oxides, using an aerodynamic levitator and a laser. The object of the invention is to provide a method for synthesizing extremely high-temperature melting materials that are otherwise difficult to produce, without the use of containers, allowing the manipulation of the phase (amorphous/crystalline/metastable) and permitting changes of the environment such as different gaseous compositions.

  8. Gravity effects on cellulose assembly

    NASA Technical Reports Server (NTRS)

    Brown, R. M. Jr; Kudlicka, K.; Cousins, S. K.; Nagy, R.; Brown RM, J. r. (Principal Investigator)

    1992-01-01

    The effect of microgravity on cellulose synthesis using the model system of Acetobacter xylinum was the subject of recent investigations using The National Aeronautics and Space Administration's Reduced Gravity Laboratory, a modified KC-135 aircraft designed to produce 20 sec of microgravity during the top of a parabolic dive. Approximately 40 parabolas were executed per mission, and a period of 2 x g was integral to the pullout phase of each parabola. Cellulose biosynthesis was initiated on agar surfaces, liquid growth medium, and buffered glucose during parabolic flight and terminated with 2.0% sodium azide or 50.0% ethanol. While careful ground and in-flight controls indicated normal, compact ribbons of microbial cellulose, data from five different flights consistently showed that during progression into the parabola regime, the cellulose ribbons became splayed. This observation suggests that some element of the parabola (the 20 sec microgravity phase, the 20 sec 2 x g phase, or a combination of both) was responsible for this effect. Presumably the cellulose I alpha crystalline polymorph normally is produced under strain, and the microgravity/hypergravity combination may relieve this stress to produce splayed ribbons. An in-flight video microscopy analysis of bacterial motions during a parabolic series demonstrated that the bacteria continue to synthesize cellulose during all phases of the parabolic series. Thus, the splaying may be a reflection of a more subtle alteration such as reduction of intermicrofibrillar hydrogen bonding. Long-term microgravity exposures during spaceflight will be necessary to fully understand the cellulose alterations from the short-term microgravity experiments.

  9. Towards electronic paper displays made from microbial cellulose.

    PubMed

    Shah, Jay; Brown, R Malcolm

    2005-01-01

    Cellulose (in the form of printed paper) has always been the prime medium for displaying information in our society and is far better than the various existing display technologies. This is because of its high reflectivity, contrast, low cost and flexibility. There is a major initiative to push for a dynamic display technology that emulates paper (popularly known as "electronic paper"). We have successfully demonstrated the proof of the concept of developing a dynamic display on cellulose. To the best of our knowledge, this is the first significant effort to achieve an electronic display using bacterial cellulose. First, bacterial cellulose is synthesized in a culture of Acetobacter xylinum in standard glucose-rich medium. The bacterial cellulose membrane thus formed (not pulp) is dimensionally stable, has a paper-like appearance and has a unique microfibrillar nanostructure. The technique then involves first making the cellulose an electrically conducting (or semi-conducting) sheet by depositing ions around the microfibrils to provide conducting pathways and then immobilizing electrochromic dyes within the microstructure. The whole system is then cased between transparent electrodes, and upon application of switching potentials (2-5 V) a reversible color change can be demonstrated down to a standard pixel-sized area (ca. 100 microm2). Using a standard back-plane or in-plane drive circuit, a high-resolution dynamic display device using cellulose as substrate can be constructed. The major advantages of such a device are its high paper-like reflectivity, flexibility, contrast and biodegradability. The device has the potential to be extended to various applications, such as e-book tablets, e-newspapers, dynamic wall papers, rewritable maps and learning tools.

  10. Gravity effects on cellulose assembly

    NASA Technical Reports Server (NTRS)

    Brown, R. M. Jr; Kudlicka, K.; Cousins, S. K.; Nagy, R.; Brown RM, J. r. (Principal Investigator)

    1992-01-01

    The effect of microgravity on cellulose synthesis using the model system of Acetobacter xylinum was the subject of recent investigations using The National Aeronautics and Space Administration's Reduced Gravity Laboratory, a modified KC-135 aircraft designed to produce 20 sec of microgravity during the top of a parabolic dive. Approximately 40 parabolas were executed per mission, and a period of 2 x g was integral to the pullout phase of each parabola. Cellulose biosynthesis was initiated on agar surfaces, liquid growth medium, and buffered glucose during parabolic flight and terminated with 2.0% sodium azide or 50.0% ethanol. While careful ground and in-flight controls indicated normal, compact ribbons of microbial cellulose, data from five different flights consistently showed that during progression into the parabola regime, the cellulose ribbons became splayed. This observation suggests that some element of the parabola (the 20 sec microgravity phase, the 20 sec 2 x g phase, or a combination of both) was responsible for this effect. Presumably the cellulose I alpha crystalline polymorph normally is produced under strain, and the microgravity/hypergravity combination may relieve this stress to produce splayed ribbons. An in-flight video microscopy analysis of bacterial motions during a parabolic series demonstrated that the bacteria continue to synthesize cellulose during all phases of the parabolic series. Thus, the splaying may be a reflection of a more subtle alteration such as reduction of intermicrofibrillar hydrogen bonding. Long-term microgravity exposures during spaceflight will be necessary to fully understand the cellulose alterations from the short-term microgravity experiments.

  11. SYNTHESIZING ORGANIC COMPOUNDS USING LIGHT-ACTIVATED TIO2

    EPA Science Inventory

    High-value organic compounds have been synthesized successfully from linear and cyclic hydrocarbons, by photocatalytic oxidation using a semiconductor material, titanium dioxide (TiO2). Various hydrocarbons were partially oxgenated in both liquid and gaseous phase reactors usi...

  12. Biologically synthesized fluorescent CdS NPs encapsulated by PHB.

    PubMed

    Pandian, Sureshbabu Ram Kumar; Deepak, Venkataraman; Kalishwaralal, Kalimuthu; Gurunathan, Sangiliyandi

    2011-04-07

    Here an attempt was made to biologically synthesize fluorescent cadmium sulfide nanoparticles and to immobilize the synthesized nanoparticles in PHB nanoparticles. The present study uses Brevibacterium casei SRKP2 as a potential producer for the green synthesis of CdS nanoparticles. Biologically synthesized nanoparticles were characterized and confirmed using electron microscopy and XRD. The size distribution of the nanoparticles was found to be 10-30 nm followed by which the consequence of time, growth of the organism, pH, concentration of CdCl(2) and Na(2)S on the synthesis of nanoparticles were checked. Enhanced synthesis and fluorescence emission of CdS nanoparticles were achieved at pH 9. The synthesized CdS NPs were immobilized with PHB and were characterized. The fluorescent intensity of the CdS nanoparticles remained unaffected even after immobilization within PHB nanoparticles.

  13. Synthesizing SoTL Institutional Initiatives toward National Impact

    ERIC Educational Resources Information Center

    Simmons, Nicola

    2016-01-01

    This chapter draws on other authors' ideas in this issue, describing parallels and outlining distinctions toward a synthesized model for the development of SoTL initiatives at the institutional level and beyond.

  14. Organic syntheses employing supercritical carbon dioxide as a reaction solvent

    NASA Technical Reports Server (NTRS)

    Barstow, Leon E. (Inventor); Ward, Glen D. (Inventor); Bier, Milan (Inventor)

    1991-01-01

    Chemical reactions are readily carried out using supercritical carbon dioxide as the reaction medium. Supercritical carbon dioxide is of special value as a reaction medium in reactions for synthesizing polypeptides, for sequencing polypeptides, or for amino acid analysis.

  15. Synthesizing SoTL Institutional Initiatives toward National Impact

    ERIC Educational Resources Information Center

    Simmons, Nicola

    2016-01-01

    This chapter draws on other authors' ideas in this issue, describing parallels and outlining distinctions toward a synthesized model for the development of SoTL initiatives at the institutional level and beyond.

  16. SYNTHESIZING ORGANIC COMPOUNDS USING LIGHT-ACTIVATED TIO2

    EPA Science Inventory

    High-value organic compounds have been synthesized successfully from linear and cyclic hydrocarbons, by photocatalytic oxidation using a semiconductor material, titanium dioxide (TiO2). Various hydrocarbons were partially oxgenated in both liquid and gaseous phase reactors usi...

  17. Organic syntheses employing supercritical carbon dioxide as a reaction solvent

    NASA Technical Reports Server (NTRS)

    Barstow, Leon E. (Inventor); Ward, Glen D. (Inventor); Bier, Milan (Inventor)

    1993-01-01

    Chemical reactions are readily carried out using supercritical carbon dioxide as the reaction medium. Supercritical carbon dioxide is of special value as a reaction medium in reactions for synthesizing polypeptides, for sequencing polypeptides, or for amino acid analysis.

  18. Efferent fibers to Limulus eyes synthesize and release octopamine.

    PubMed

    Batelle, B A; Evans, J A; Chamberlain, S C

    1982-06-11

    Octopamine synthesized in vitro from tyramine by Limulus lateral and ventral eyes was located by light microscopic and electron microscopic autoradiography in efferent fibers which innervate ventral photoreceptors and lateral eye ommatidia. Newly synthesized octopamine was released from efferent fibers in response to depolarization in high concentrations of potassium. We propose that octopamine is a neurotransmitter of efferent fibers that may modulate basic retinal processes such as photoreceptor sensitivity, photomechanical movements, and photoreceptive membrane turnover.

  19. Perceptual Error Analysis of Human and Synthesized Voices.

    PubMed

    Englert, Marina; Madazio, Glaucya; Gielow, Ingrid; Lucero, Jorge; Behlau, Mara

    2017-07-01

    To assess the quality of synthesized voices through listeners' skills in discriminating human and synthesized voices. Prospective study. Eighteen human voices with different types and degrees of deviation (roughness, breathiness, and strain, with three degrees of deviation: mild, moderate, and severe) were selected by three voice specialists. Synthesized samples with the same deviations of human voices were produced by the VoiceSim system. The manipulated parameters were vocal frequency perturbation (roughness), additive noise (breathiness), increasing tension, subglottal pressure, and decreasing vocal folds separation (strain). Two hundred sixty-nine listeners were divided in three groups: voice specialist speech language pathologists (V-SLPs), general clinician SLPs (G-SLPs), and naive listeners (NLs). The SLP listeners also indicated the type and degree of deviation. The listeners misclassified 39.3% of the voices, both synthesized (42.3%) and human (36.4%) samples (P = 0.001). V-SLPs presented the lowest error percentage considering the voice nature (34.6%); G-SLPs and NLs identified almost half of the synthesized samples as human (46.9%, 45.6%). The male voices were more susceptible for misidentification. The synthesized breathy samples generated a greater perceptual confusion. The samples with severe deviation seemed to be more susceptible for errors. The synthesized female deviations were correctly classified. The male breathiness and strain were identified as roughness. VoiceSim produced stimuli very similar to the voices of patients with dysphonia. V-SLPs had a better ability to classify human and synthesized voices. VoiceSim is better to simulate vocal breathiness and female deviations; the male samples need adjustment. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

  20. SYNTHESIZER CONTROLLED BEAM TRANSFER FROM THE AGS TO RHIC.

    SciTech Connect

    DELONG,J.; BRENNAN,J.M.; FISCHER,W.; HAYES,T.; SMITH,K.; VALENTINO,S.

    2001-06-18

    To ensure minimal losses and to preserve longitudinal emittance, beam is transferred from the AGS to the RHIC bunch to bucket. This requires precision frequency and phase control for synchronization and kicker timing. The required precision is realized with a set of Direct Digital Synthesizers. Each synthesizer can be frequency and phase modulated to align the AGS bunch to the target bucket in the RHIC phase.

  1. Vanadium oxide electrode synthesized by electroless deposition for electrochemical capacitors

    NASA Astrophysics Data System (ADS)

    Wu, Haoran; Lian, Keryn

    2014-12-01

    A thin film vanadium oxide electrode was synthesized by a simple electroless deposition method. Surface and structural analyses revealed that the deposited oxide is a mixture of amorphous V2O5 and VO2. Electrochemical characterizations of the synthesized vanadium oxide showed capacitive behavior with good cycle life. The electroless deposition of vanadium oxide is inexpensive, easy to process, and environmentally benign, offering a promising route for electrode development for electrochemical capacitors.

  2. Mayenite Synthesized Using the Citrate Sol-Gel Method

    SciTech Connect

    Ude, Sabina N; Rawn, Claudia J; Meisner, Roberta A; Kirkham, Melanie J; Jones, Gregory L.; Payzant, E Andrew

    2014-01-01

    A citrate sol-gel method has been used to synthesize mayenite (Ca12Al14O33). X-ray powder diffraction data show that the samples synthesized using the citrate sol-gel method contained CaAl2O4 and CaCO3 along with mayenite when fired ex-situ in air at 800 C but were single phase when fired at 900 C and above. Using high temperature x-ray diffraction, data collected in-situ in air at temperatures of 600 C and below showed only amorphous content; however, data collected at higher temperatures indicated the first phase to crystallize is CaCO3. High temperature x-ray diffraction data collected in 4% H2/96% N2 does not show the presence of CaCO3, and Ca12Al14O33 starts to form around 850 C. In comparison, x-ray powder diffraction data collected ex-situ on samples synthesized using traditional solid-state synthesis shows that single phase was not reached until samples were fired at 1350 C. DTA/TGA data collected either in a nitrogen environment or air on samples synthesized using the citrate gel method suggest the complete decomposition of metastable phases and the formation of mayenite at 900 C, although the phase evolution is very different depending on the environment. Brunauer-Emmett-Teller (BET) measurements showed a slightly higher surface area of 7.4 0.1 m2/g in the citrate gel synthesized samples compared to solid-state synthesized sample with a surface area of 1.61 0.02 m2/g. SEM images show a larger particle size for samples synthesized using the solid-state method compared to those synthesized using the citrate gel method.

  3. Direct visualization of identified and newly synthesized proteins in situ

    PubMed Central

    Dieck, Susanne tom; Kochen, Lisa; Hanus, Cyril; Bartnik, Ina; Nassim-Assir, Belquis; Merk, Katrin; Mosler, Thorsten; Garg, Sakshi; Bunse, Stefanie; Tirrell, David A.; Schuman, Erin M.

    2015-01-01

    Protein synthesis is a dynamic process to tune the cellular proteome to internal and external demands. Metabolic labeling approaches identify the general proteomic response but missing is a tool to visualize within cells specific newly synthesized proteins. Here we describe a technique that couples non-canonical amino acid tagging or puromycylation with the proximity-ligation assay to visualize identified newly synthesized proteins and monitor their origin, redistribution and turnover in situ. PMID:25775042

  4. Enantioselective Chemical Syntheses of the Furanosteroids (-)-Viridin and (-)-Viridiol.

    PubMed

    Del Bel, Matthew; Abela, Alexander R; Ng, Jeffrey D; Guerrero, Carlos A

    2017-05-24

    Herein we describe concise enantioselective chemical syntheses of (-)-viridin and (-)-viridiol. Our convergent approach couples two achiral fragments of similar complexity and employs an enantioselective intramolecular Heck reaction to set the absolute stereochemical configuration of an all-carbon quaternary stereocenter. To complete the syntheses of these base- and nucleophile-sensitive natural products, we conduct carefully orchestrated site- and diastereoselective oxidations and other transformations. Our work is the first to generate these targets as single enantiomers.

  5. Degradation of Methylene Blue Using Biologically Synthesized Silver Nanoparticles

    PubMed Central

    Vanaja, M.; Paulkumar, K.; Baburaja, M.; Rajeshkumar, S.; Gnanajobitha, G.; Malarkodi, C.; Sivakavinesan, M.; Annadurai, G.

    2014-01-01

    Nowadays plant mediated synthesis of nanoparticles has great interest and achievement due to its eco-benign and low time consuming properties. In this study silver nanoparticles were successfully synthesized by using Morinda tinctoria leaf extract under different pH. The aqueous leaf extract was added to silver nitrate solution; the color of the reaction medium was changed from pale yellow to brown and that indicates reduction of silver ions to silver nanoparticles. Thus synthesized silver nanoparticles were characterized by UV-Vis spectrophotometer. Dispersity and morphology was characterized by scanning electron microscope (SEM); crystalline nature and purity of synthesized silver nanoparticles were revealed by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). FTIR spectrum was examined to identify the effective functional molecules responsible for the reduction and stabilization of silver nanoparticles synthesized by leaf extract. The photocatalytic activity of the synthesized silver nanoparticles was examined by degradation of methylene blue under sunlight irradiation. Green synthesized silver nanoparticles were effectively degrading the dye nearly 95% at 72 h of exposure time. PMID:24772055

  6. Degradation of methylene blue using biologically synthesized silver nanoparticles.

    PubMed

    Vanaja, M; Paulkumar, K; Baburaja, M; Rajeshkumar, S; Gnanajobitha, G; Malarkodi, C; Sivakavinesan, M; Annadurai, G

    2014-01-01

    Nowadays plant mediated synthesis of nanoparticles has great interest and achievement due to its eco-benign and low time consuming properties. In this study silver nanoparticles were successfully synthesized by using Morinda tinctoria leaf extract under different pH. The aqueous leaf extract was added to silver nitrate solution; the color of the reaction medium was changed from pale yellow to brown and that indicates reduction of silver ions to silver nanoparticles. Thus synthesized silver nanoparticles were characterized by UV-Vis spectrophotometer. Dispersity and morphology was characterized by scanning electron microscope (SEM); crystalline nature and purity of synthesized silver nanoparticles were revealed by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). FTIR spectrum was examined to identify the effective functional molecules responsible for the reduction and stabilization of silver nanoparticles synthesized by leaf extract. The photocatalytic activity of the synthesized silver nanoparticles was examined by degradation of methylene blue under sunlight irradiation. Green synthesized silver nanoparticles were effectively degrading the dye nearly 95% at 72 h of exposure time.

  7. Transition metal oxide nanowires synthesized by heating metal substrates

    SciTech Connect

    Yan, Hui; Sun, Yi; He, Lin; Nie, Jia-Cai

    2011-11-15

    Highlights: {center_dot} This paper describes a simple and general method to synthesize 3d metal oxide nanowires. {center_dot} Self-catalysis growth mechanism was proposed to explain the growth of the nanowires. {center_dot} The temperature range for the growth of nanowires was estimated by taking into account the Gibbs free energy of reaction. {center_dot} This synthesis approach could be applied to synthesize other one-dimensional structures, such as FeSe and Bi{sub 2}Te{sub 3} nanowires. -- Abstract: Here we reported a simple method to synthesize transition metal oxide nanowires. Copper oxide (CuO), zinc oxide (ZnO), and cobalt oxide (Co{sub 3}O{sub 4}) nanowires were synthesized by heating the copper, zinc, and cobalt substrates under atmosphere condition. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to analyze the morphology and microstructure of the nanowires. According to our experimental results, self-catalysis growth mechanism was proposed to explain the growth of the nanowires. The temperature window for the growth of nanowires was estimated by taking into account the Gibbs free energy of reaction. The synthesis approach observed in our experiment could be applied to synthesize other one-dimensional structures, such as FeSe and Bi{sub 2}Te{sub 3} nanowires.

  8. Iron oxide magnetic nanoparticles synthesized by atmospheric microplasmas

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Kaur, Parvin; Tan, Augustine Tuck Lee; Singh, Rajveer; Lee, Paul Choon Keat; Springham, Stuart Victor; Ramanujan, Raju V.; Rawat, R. S.

    2014-08-01

    This paper presents the synthesis of iron oxide nanoparticles using the atmospheric microplasma (AMP). The properties of iron oxide nanoparticles synthesized using AMP are compared with particles (i) formed in as-prepared solution and (ii) prepared using thermal decomposition method. Iron oxide nanoparticles prepared by all the 3 treatment methods exhibit quite soft ferromagnetic properties with coercivities less than 10 G. The AMP synthesis technique was found to be more efficient and better than thermal decomposition method due to ultra-shorter experiment time (around 2.5 min) as compared to 90 min required for thermal decomposition method. Moreover, AMP synthesized nanoparticles are better isolated and of smaller size than thermal decomposition ones. The effect of plasma discharge timings on synthesized nanoparticles has also been studied in this work. Coercivity of synthesized nanoparticles decreases with the increasing plasma discharge timings from 3 to 10 min. The nanoparticles synthesized using plasma discharge timing of 10 min exhibit the smallest coercivity of around 3 G. This suggests a high possibility of achieving super-paramagnetic nanoparticles by optimizing the plasma discharge timings of AMP.

  9. Evaluation of green synthesized silver nanoparticles against parasites.

    PubMed

    Marimuthu, Sampath; Rahuman, Abdul Abdul; Rajakumar, Govindasamy; Santhoshkumar, Thirunavukkarasu; Kirthi, Arivarasan Vishnu; Jayaseelan, Chidambaram; Bagavan, Asokan; Zahir, Abdul Abduz; Elango, Gandhi; Kamaraj, Chinnaperumal

    2011-06-01

    Green nanoparticle synthesis has been achieved using environmentally acceptable plant extract and eco-friendly reducing and capping agents. The present study was based on assessments of the antiparasitic activities to determine the efficacies of synthesized silver nanoparticles (AgNPs) using aqueous leaf extract of Mimosa pudica Gaertn (Mimosaceae) against the larvae of malaria vector, Anopheles subpictus Grassi, filariasis vector Culex quinquefasciatus Say (Diptera: Culicidae), and Rhipicephalus (Boophilus) microplus Canestrini (Acari: Ixodidae). Parasite larvae were exposed to varying concentrations of aqueous extract of M. pudica and synthesized AgNPs for 24 h. AgNPs were rapidly synthesized using the leaf extract of M. pudica and the formation of nanoparticles was observed within 6 h. The results recorded from UV-vis spectrum, Fourier transform infrared, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy support the biosynthesis and characterization of AgNPs. The maximum efficacy was observed in synthesized AgNPs against the larvae of A. subpictus, C. quinquefasciatus, and R. microplus (LC(50) = 13.90, 11.73, and 8.98 mg/L, r (2) = 0.411, 0.286, and 0.479), respectively. This is the first report on antiparasitic activity of the plant extract and synthesized AgNPs.

  10. Effects of perceptual training based upon synthesized voice signals.

    PubMed

    Martin, D P; Wolfe, V I

    1996-12-01

    28 undergraduate students participated in a perceptual voice experiment to assess the effects of training utilizing synthesized voice signals. An instructional strategy based upon synthesized examples of a three-part classification system: "breathy," "rough," and "hoarse," was employed. Training samples were synthesized with varying amounts of jitter (cycle-to-cycle deviation in pitch period) and harmonic-to-noise ratios to represent these qualities. Before training, listeners categorized 60 pathological voices into "breathy," "rough," and "hoarse," largely on the basis of fundamental frequency. After training, categorizations were influenced by harmonic-to-noise ratios as well as fundamental frequency, suggesting that listeners were more aware of spectral differences in pathological voices associated with commonly occurring laryngeal conditions. 40% of the pathological voice samples remained unclassified following training.

  11. [A method of synthesizing cicada sound for treatment of tinnitus].

    PubMed

    Wang, Yangjing; He, Peiyu; Pan, Fan; Cui, Tao; Wang, Haiyan

    2013-06-01

    Masking therapy can make patients accustom to tinnitus. This therapy is safe and easy to implement, so that it has become a widely used treatment of curing tinnitus. According to surveys of tinnitus sounds, cicada sound is one of the most usual tinnituses. Meanwhile, we have not hitherto found published papers concerning how to synthesize cicada sound and to use it to ameliorate tinnitus. Inspired by the human acoustics theory, we proposed a method to synthesize medical masking sound and to realize the diversity by illustrating the process of synthesizing various cicada sounds. In addition, energy attenuation problem in spectrum shifting process has been successfully solved. Simulation results indicated that the proposed method achieved decent results and would have practical value for the future applications.

  12. Squid photoreceptor terminals synthesize calexcitin, a learning related protein.

    PubMed

    Eyman, Maria; Crispino, Marianna; Kaplan, Barry B; Giuditta, Antonio

    2003-08-14

    Nerve endings of squid photoreceptor neurons generate large synaptosomes upon homogenization of the optic lobe. Using several independent methods, these presynaptic structures have been shown to synthesize a wealth of soluble, cytoskeletal and nuclear encoded mitochondrial proteins, and to account for essentially all the translation activity of the synaptosomal fraction. We are now presenting evidence that calexcitin, a learning related, Ca(2+)-binding protein of the B photoreceptors of Hermissenda crassicornis (a mollusk), is synthesized and subjected to post-translational modifications in the squid photoreceptor terminals. In view of the essential role of presynaptic protein synthesis in long-term memory formation in Aplysia, our data suggest that a comparable role may be played by calexcitin synthesized in the squid photoreceptor terminals.

  13. Comparison of Pyrolysis Characteristics of degreased and synthesized Mongolian Pine

    NASA Astrophysics Data System (ADS)

    Wang, Kaige; Wang, Shurong; Guo, Xiujuan; Luo, Zhongyang; Fransson, Torsten

    2010-11-01

    In order to study the influence of components' cross-interaction on biomass pyrolysis, research of degreased and synthesized Mongolian Pine (MP) was performed on a thermogravimetric analyzer coupled with a Fourier transform infrared spectroscopy (TG-FTIR) and the fast pyrolysis device. Compared with synthesized MP, the thermal behavior of degreased MP is much closer to the original and the degreased MP produces less aldehydes, alcohols or phenols and acids due to the cross-interactions of components. Synthesized MP has lower bio-oil yield and higher gas production than the degreased one. And the contents of furfural, acetic acid and levoglucosan change with the kind of samples obviously due to the intense cross-interactions of components.

  14. Bottom-Up Syntheses and Characterization of One Dimensional Nanomaterials

    NASA Astrophysics Data System (ADS)

    Yeh, Yao-Wen

    Nanomaterials, materials having at least one dimension below 100 nm, have been creating exciting opportunities for fundamental quantum confinement studies and applications in electronic devices and energy technologies. One obvious and important aspect of nanomaterials is their production. Although nanostructures can be obtained by top-down reductive e-beam lithography and focused ion beam processes, further development of these processes is needed before these techniques can become practical routes to large scale production. On the other hand, bottom-up syntheses, with advantages in material diversity, throughput, and the potential for large volume production, may provide an alternative strategy for creating nanostructures. In this work, we explore syntheses of one dimensional nanostructures based on hydrothermal and arc discharge methods. The first project presented in this thesis involves syntheses of technologically important nanomaterials and their potential application in energy harvesting. In particular, it was demonstrated that single crystal ferroelectric lead magnesium niobate lead titanate (PMN-PT) nanowires can be synthesized by a hydrothermal route. The chemical composition of the synthesized nanowires is near the rhombohedral-monoclinic boundary of PMN-PT, which leads to a high piezoelectric coefficient of 381 pm/V. Finally, the potential use of PMN-PT nanowires in energy harvesting applications was also demonstrated. The second part of this thesis involves the synthesis of carbon and boron nitride nanotubes by dc arc discharges. In particular, we investigated how local plasma related properties affected the synthesis of carbon nanostructures. Finally, we investigated the anodic nature of the arc and how a dc arc discharge can be applied to synthesize boron nitride nanotubes.

  15. Fatty acid alcohol ester-synthesizing activity of lipoprotein lipase.

    PubMed

    Tsujita, T; Sumiyoshi, M; Okuda, H

    1999-12-01

    The fatty acid alcohol ester-synthesizing activity of lipoprotein lipase (LPL) was characterized using bovine milk LPL. Synthesizing activities were determined in an aqueous medium using oleic acid or trioleylglycerol as the acyl donor and equimolar amounts of long-chain alcohols as the acyl acceptor. When oleic acid and hexadecanol emulsified with gum arabic were incubated with LPL, palmityl oleate was synthesized, in a time- and dose-dependent manner. Apo-very low density lipoprotein (apoVLDL) stimulated LPL-catalyzed palmityl oleate synthesis. The apparent equilibrium ratio of fatty acid alcohol ester/oleic acid was estimated using a high concentration of LPL and a long (20 h) incubation period. The equilibrium ratio was affected by the incubation pH and the alcohol chain length. When the incubation pH was below pH 7.0 and long chain fatty acyl alcohols were used as substrates, the fatty acid alcohol ester/free fatty acid equilibrium ratio favored ester formation, with an apparent equilibrium ratio of fatty acid alcohol ester/fatty acid of about 0.9/0.1. The equilibrium ratio decreased sharply at alkaline pH (above pH 8.0). The ratio also decreased when fatty alcohols with acyl chains shorter than dodecanol were used. When a trioleoylglycerol/fatty acyl alcohol emulsion was incubated with LPL, fatty acid alcohol esters were synthesized in a dose- and time-dependent fashion. Fatty acid alcohol esters were easily synthesized from trioleoylglycerol when fatty alcohols with acyl chains longer than dodecanol were used, but synthesis was decreased with fatty alcohols with acyl chain lengths shorter than decanol, and little synthesizing activity was detected with shorter-chain fatty alcohols such as butanol or ethanol.

  16. [Detection of synthesized microsomal hemoproteins (cytochrome P-448) using autofluorography].

    PubMed

    Chasovnikova, O B; Tsyrlov, I B

    1986-01-01

    Simple and informative method for the elucidation of de novo synthesized forms of microsomal cytochrome P-448 induced by 3-methylcholanthrene and 2,3,7,8-tetrachlordibenzo-p-dioxine has been developed. The method is based on gel fluorography upon electrophoretic separation of microsomal proteins obtained from the liver of rats pre-treated with the inducers of monooxygenase system components and then with 14C-leucine. At least two forms of cytochrome P-448 (with molecular weight of 56000 and 53000) were shown to be de novo synthesized under the influence of 3-methylcholanthrene and 2,3,7,8-tetrachlodbibenzo-p-dioxine.

  17. Diameter Controlled of Carbon Nanotubes Synthesized on Nanoporous Silicon Support

    NASA Astrophysics Data System (ADS)

    Asli, N. A.; Shamsudin, M. S.; Maryam, M.; Yusop, S. F. M.; Suriani, A. B.; Rusop, M.; Abdullah, S.

    2013-06-01

    Carbon nanotubes (CNTs) have been successfully synthesized on nanoporous silicon template (NPSiT) using botanical source, camphor oil. Diameter of CNTs synthesized was controlled by pore size of NPSiT prepared by photo-electrochemical anodization method. The diameter of CNTs grown on different NPSiT corresponded to the pore diameter of NPSiT. FESEM images showed self-organized bundles of fiber-like structures of CNTs with diameter of around 20nm which were successfully grown directly on nanoporous silicon while raman spectra obtained ratio of ID/IG at 0.67.

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

    SciTech Connect

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

    2015-08-28

    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)

  19. Stereocontrolled semi-syntheses of deguelin and tephrosin.

    PubMed

    Russell, David A; Freudenreich, Julien J; Ciardiello, Joe J; Sore, Hannah F; Spring, David R

    2017-02-21

    We describe stereocontrolled semi-syntheses of deguelin and tephrosin, anti-cancer rotenoids isolated from Tephrosia vogelii. Firstly, we present a new two-step transformation of rotenone into rot-2'-enonic acid via a zinc-mediated ring opening of rotenone hydrobromide. Secondly, following conversion of rot-2'-enonic acid into deguelin, a chromium-mediated hydroxylation provides tephrosin as a single diastereoisomer. An Étard-like reaction mechanism is proposed to account for the stereochemical outcome. Our syntheses of deguelin and tephrosin are operationally simple, scalable and high yielding, offering considerable advantages over previous methods.

  20. Nano- and macroscale structural and mechanical properties of in situ synthesized bacterial cellulose/PEO-b-PPO-b-PEO biocomposites.

    PubMed

    Tercjak, Agnieszka; Gutierrez, Junkal; Barud, Hernane S; Domeneguetti, Rafael R; Ribeiro, Sidney J L

    2015-02-25

    Highly transparent biocomposite based on bacterial cellulose (BC) mat modified with poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) block copolymer (EPE) were fabricated in situ during biosynthesis of bacterial cellulose in a static culture from Gluconacetobacter xylinum. The effect of the addition to the culture medium of water-soluble EPE block copolymer on structure, morphology, crystallinity, and final properties of the novel biocomposites was investigated at nano- and macroscale. High compatibility between components was confirmed by ATR-FTIR indicating hydrogen bond formation between the OH group of BC and the PEO block of EPE block copolymer. Structural properties of EPE/BC biocomposites showed a strong effect of EPE block copolymer on the morphology of the BC mats. Thus, the increase of the EPE block copolymer content lead to the generation of spherulites of PEO block, clearly visualized using AFM and MO technique, changing crystallinity of the final EPE/BC biocomposites investigated by XRD. Generally, EPE/BC biocomposites maintain thermal stability and mechanical properties of the BC mat being 1 wt % EPE/BC biocomposite material with the best properties. Biosynthesis of EPE/BC composites open new strategy to the utilization of water-soluble block copolymers in the preparation of BC mat based biocomposites with tunable properties.

  1. Synthesizing a Life: An Interview with Carl Djerassi

    ERIC Educational Resources Information Center

    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…

  2. Numerically Controlled Phase Locked Loop Using Direct Digital Synthesizer

    SciTech Connect

    Pei, Alex

    1993-04-13

    A direct digital synthesizer is a highly stable digitally controlled frequency generator that outputs high spectrum purity rf signals. Because of the all digital design, it is immune to various environmental disturbances that plague conventional LC based VCOs. As a result, a PLL based on DDS can achieve high spectrum purity with very narrow tracking bandwidth.

  3. Synthesizing genetic sequential logic circuit with clock pulse generator.

    PubMed

    Chuang, Chia-Hua; Lin, Chun-Liang

    2014-05-28

    Rhythmic clock widely occurs in biological systems which controls several aspects of cell physiology. For the different cell types, it is supplied with various rhythmic frequencies. How to synthesize a specific clock signal is a preliminary but a necessary step to further development of a biological computer in the future. This paper presents a genetic sequential logic circuit with a clock pulse generator based on a synthesized genetic oscillator, which generates a consecutive clock signal whose frequency is an inverse integer multiple to that of the genetic oscillator. An analogous electronic waveform-shaping circuit is constructed by a series of genetic buffers to shape logic high/low levels of an oscillation input in a basic sinusoidal cycle and generate a pulse-width-modulated (PWM) output with various duty cycles. By controlling the threshold level of the genetic buffer, a genetic clock pulse signal with its frequency consistent to the genetic oscillator is synthesized. A synchronous genetic counter circuit based on the topology of the digital sequential logic circuit is triggered by the clock pulse to synthesize the clock signal with an inverse multiple frequency to the genetic oscillator. The function acts like a frequency divider in electronic circuits which plays a key role in the sequential logic circuit with specific operational frequency. A cascaded genetic logic circuit generating clock pulse signals is proposed. Based on analogous implement of digital sequential logic circuits, genetic sequential logic circuits can be constructed by the proposed approach to generate various clock signals from an oscillation signal.

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

    EPA Science Inventory

    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...

  5. Syntheses of Cyclic Guanidine-Containing Natural Products.

    PubMed

    Ma, Yuyong; De, Saptarshi; Chen, Chuo

    2015-02-25

    Naturally occurring guanidine derivatives frequently display medicinally useful properties. Among them, the higher order pyrrole-imidazole alkaloids, the dragmacidins, the crambescidins/batzelladines, and the saxitoxins/tetradotoxins have stimulated the development of many new synthetic methods over the past decades. We provide here an overview of the syntheses of these cyclic guanidine-containing natural products.

  6. Strengthening syntheses on fire: Increasing their usefulness for managers

    Treesearch

    Jane Kapler Smith

    2015-01-01

    A synthesis for fire managers summarizes and interprets a body of information, presents its meaning in an objective, unbiased way, and describes its implications for decisionmakers. Following are suggestions for ways to strengthen syntheses on fire and on other natural resource issues:Include managers, scientists, and...

  7. Meta-Analysis: A Systematic Method for Synthesizing Counseling Research

    ERIC Educational Resources Information Center

    Whiston, Susan C.; Li, Peiwei

    2011-01-01

    The authors provide a template for counseling researchers who are interested in quantitatively aggregating research findings. Meta-analytic studies can provide relevant information to the counseling field by systematically synthesizing studies performed by researchers from diverse fields. Methodologically sound meta-analyses require careful…

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

    ERIC Educational Resources Information Center

    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…

  9. Syntheses of naturally occurring terphenyls and related compounds.

    PubMed

    Sawayama, Yusuke; Tsujimoto, Takashi; Sugino, Kumi; Nishikawa, Toshio; Isobe, Minoru; Kawagishi, Hirokazu

    2006-12-01

    Naturally occurring terphenyls and related compounds such as terferol and its corresponding quinone and phlebiarubrone were synthesized from 2,5-diphenyl-1,4-benzoquinone. According to the proposed biosynthetic pathway, chemical conversion of phlebiarubrone to ustalic acid, a toxic compound isolated from the poisonous mushroom, Tricholoma ustale, was examined to find a low-yield conversion to the ustalic acid dimethyl ester.

  10. Branched nanostructures and method of synthesizing the same

    NASA Technical Reports Server (NTRS)

    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.

  11. Function generator for synthesizing complex vibration mode patterns

    NASA Technical Reports Server (NTRS)

    Naumann, E. C.; Hagood, G. J., Jr. (Inventor)

    1973-01-01

    A simple highly flexible device for synthesizing complex vibration mode patterns is described. These mode patterns can be used to identify vibration mode data. This device sums selected sine and cosine functions and then plots the sum against a linear function.

  12. Synthesizing a Life: An Interview with Carl Djerassi

    ERIC Educational Resources Information Center

    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…

  13. Antimicrobial activity of the synthesized non-allergenic urushiol derivatives.

    PubMed

    Cho, Jeong-Yong; Park, Keun Young; Kim, Seon-Jae; Oh, Sejong; Moon, Jae-Hak

    2015-01-01

    Synthesized urushiol derivatives possessing different carbon atomic length in the alkyl side chain inhibited the growth of food spoilage and pathogenic microorganisms. Particularly, non-allergenic 3-pentylcatechol showed a broad antimicrobial spectrum on an agar plate. Most food spoilage and pathogenic microorganisms were sensitive to urushiol derivatives in the liquid culture. The morphologies of the microorganisms were changed after treatment of 3-pentylcatechol.

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

    ERIC Educational Resources Information Center

    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…

  15. Meta-Analysis: A Systematic Method for Synthesizing Counseling Research

    ERIC Educational Resources Information Center

    Whiston, Susan C.; Li, Peiwei

    2011-01-01

    The authors provide a template for counseling researchers who are interested in quantitatively aggregating research findings. Meta-analytic studies can provide relevant information to the counseling field by systematically synthesizing studies performed by researchers from diverse fields. Methodologically sound meta-analyses require careful…

  16. Uses of a Vinylpyridine Polymer in Undergraduate Organic Syntheses.

    ERIC Educational Resources Information Center

    Getman, Damon; And Others

    1984-01-01

    Presents a series of syntheses in which poly-4-vinylpyridine is substituted for pyridine or other tertiary amines, avoiding some of the safety problems associated with traditional reagents and providing a readily recoverable and recyclable reactant. Background information, procedures used, and results are included. (JN)

  17. Irradiation study of PNNL synthesized glass-ceramics

    SciTech Connect

    Kossoy-simakov, Anna-eden; Tang, Ming; Valdez, James A; Usov, Igor O; Sickafus, Kurt E

    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.

  18. Biomedical applications of green synthesized Nobel metal nanoparticles.

    PubMed

    Khan, Zia Ul Haq; Khan, Amjad; Chen, Yongmei; Shah, Noor S; Muhammad, Nawshad; Khan, Arif Ullah; Tahir, Kamran; Khan, Faheem Ullah; Murtaza, Behzad; Hassan, Sadaf Ul; Qaisrani, Saeed Ahmad; Wan, Pingyu

    2017-08-01

    Synthesis of Nobel metal nanoparticles, play a key role in the field of medicine. Plants contain a substantial number of organic constituents, like phenolic compounds and various types of glycosides that help in synthesis of metal nanoparticles. Synthesis of metal nanoparticles by green method is one of the best and environment friendly methods. The major significance of the green synthesis is lack of toxic by-products produced during metal nanoparticle synthesis. The nanoparticles, synthesized by green method show various significant biological activities. Most of the research articles report the synthesized nanoparticles to be active against gram positive and gram negative bacteria. Some of these bacteria include Escherichia coli, Bacillus subtilis, Klebsiella pneumonia and Pseudomonas fluorescens. The synthesized nanoparticles also show significant antifungal activity against Trichophyton simii, Trichophyton mentagrophytes and Trichophyton rubrum as well as different types of cancer cells such as breast cancer cell line. They also exhibit significant antioxidant activity. The activities of these Nobel metal nano-particles mainly depend on the size and shape. The particles of small size with large surface area show good activity in the field of medicine. The synthesized nanoparticles are also active against leishmanial diseases. This research article explores in detail the green synthesis of the nanoparticles and their uses thereof. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Syntheses and insulin-like activity of phosphorylated galactose derivatives.

    PubMed

    Caro, H N; Martín-Lomas, M; Bernabé, M

    1993-02-24

    The syntheses of the poly-phosphorylated galactosides 6, 8, 10, 13, 16, and 20, isolated as sodium salts, have been performed. The non-phosphorylated disaccharide 17 and trisaccharide 21 have been prepared via glycosylation of the 2-(trimethylsilyl)ethyl galactosides 3 and 2, respectively, and subsequent complete deprotection. Preliminary insulin-like activity of the phosphorylated derivatives is reported.

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

    DOEpatents

    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.

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

    DOEpatents

    Callstrom, Matthew R.; Bednarski, Mark D.; Gruber, Patrick R.

    1997-01-01

    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.

  2. Syntheses of sugar poly(orthoesters) through reverse anomeric effect.

    PubMed

    Li, Lingyao; Wang, Jun; Obrinske, Melissa; Milligan, Ian; O'Hara, Kylie; Bitterman, Lindsay; Du, Wenjun

    2015-04-25

    High molecular weight sugar poly(orthoesters) were synthesized through reverse anomeric effect (RAE). We demonstrated that when RAE-enabled promoters, such as 4-(dimethylamino)pyridine (DMAP), triphenylphosphine (TPP) or imidazole, were employed, efficient polymerizations were achieved, giving sugar poly(orthoesters) with molecular weights up to 18 kDa.

  3. Traction in elastohydrodynamic line contacts for two synthesized hydrocarbon fluids

    NASA Technical Reports Server (NTRS)

    Trachman, E. G.; Cheng, H. S.

    1973-01-01

    The paper describes the disk machine designed and constructed for the investigation of the traction in elastohydrodynamic line contacts for two synthesized hydrocarbon fluids. The results of this experimental study are presented and compared with the theoretical predictions of traction according to the thermal and non-Newtonian theory recently presented by the authors.

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

    EPA Science Inventory

    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...

  5. Syntheses of Cyclic Guanidine-Containing Natural Products

    PubMed Central

    Ma, Yuyong; De, Saptarshi; Chen, Chuo

    2014-01-01

    Naturally occurring guanidine derivatives frequently display medicinally useful properties. Among them, the higher order pyrrole-imidazole alkaloids, the dragmacidins, the crambescidins/batzelladines, and the saxitoxins/tetradotoxins have stimulated the development of many new synthetic methods over the past decades. We provide here an overview of the syntheses of these cyclic guanidine-containing natural products. PMID:25684829

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

    ERIC Educational Resources Information Center

    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…

  7. Antimicrobial and mosquitocidal activity of microbial synthesized silver nanoparticles.

    PubMed

    Soni, Namita; Prakash, Soam

    2015-03-01

    Microbial synthesis of nanoparticles is a green approach that interconnects nanotechnology and microbial biotechnology. Here, we synthesized the silver nanoparticles (AgNPs) using bacterial strains of Listeria monocytogenes, Bacillus subtilius and Streptomyces anulatus. We tested the efficacy of AgNPs against the larvae, pupae and adults of Anopheles stephensi and Culex quinquefasciatus. We have also investigated the antifungal activity of AgNPs against the soil keratinophilic fungus of Chrysosporium keratinophilum. The efficacy tests were then performed at different concentrations and varying numbers of hours by probit analysis. The results were obtained using a UV-visible spectrophotometer, and the images were recorded with a transmission electron microscope (TEM). The synthesized AgNPs were in varied shape and sizes. The larvae and pupae of Cx. quinquefasciatus were found highly susceptible to AgNPs synthesized using the L. monocytogenes, B. subtilius and S. anulatus than the An. stephensi, while the adults of An. stephensi were found more susceptible to the AgNPs synthesized using the L. monocytogenes, B. subtilius and S. anulatus the Cx. quinquefasciatus. Further, these nanoparticles have also been tested as antifungal activity against the entomopathogenic fungus C. keratinophilum. The higher zone of inhibition occurred at the concentration level of 50 μl. This study gives an innovative approach to develop eco-friendly AgNPs which act as an effective antifungal agent/fungicide and insecticide.

  8. Evaluation of Hydrothermally Synthesized Uranium Dioxide for Novel Semiconductor Applications

    DTIC Science & Technology

    2016-08-29

    Laboratory has had recent success in synthesizing single crystal UO2 using a hydrothermal growth process. The stoichiometry and single-crystal nature...28 2.5 Hydrothermal Crystal Growth ..............................................................................30 2.6...Stoichiometry and Oxygen Defects ......................................................................35 III. Crystal Growth and Characterization

  9. Thermotoga lettingae Can Salvage Cobinamide To Synthesize Vitamin B12

    PubMed Central

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

    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 pathway to synthesize B12. In this study, these hypotheses were tested, and we found that Tt. lettingae did not synthesize B12 de novo but salvaged cobinamide. The growth rate of Tt. lettingae increased with the addition of B12 or cobinamide to its medium. It synthesized B12 when the medium was supplemented with cobinamide, and no B12 was detected in cells grown on cobinamide-deficient medium. Upstream of the cobinamide salvage genes is a putative B12 riboswitch. In other organisms, B12 riboswitches allow for higher transcriptional activity in the absence of B12. When Tt. lettingae was grown with no B12, the salvage genes were upregulated compared to cells grown with B12 or cobinamide. Another gene cluster with a putative B12 riboswitch upstream is the btuFCD ABC transporter, and it showed a transcription pattern similar to that of the cobinamide salvage genes. The BtuF proteins from species that can and cannot salvage cobinamides were shown in vitro to bind both B12 and cobinamide. These results suggest that Thermotogales species can use the BtuFCD transporter to import both B12 and cobinamide, even if they cannot salvage cobinamide. PMID:24014541

  10. Taenia solium tapeworms synthesize corticosteroids and sex steroids in vitro.

    PubMed

    Valdez, R A; Jiménez, P; Fernández Presas, A M; Aguilar, L; Willms, K; Romano, M C

    2014-09-01

    Cysticercosis is a disease caused by the larval stage of Taenia solium cestodes that belongs to the family Taeniidae that affects a number of hosts including humans. Taeniids tapeworms are hermaphroditic organisms that have reproductive units called proglottids that gradually mature to develop testis and ovaries. Cysticerci, the larval stage of these parasites synthesize steroids. To our knowledge there is no information about the capacity of T. solium tapeworms to metabolize progesterone or other precursors to steroid hormones. Therefore, the aim of this paper was to investigate if T. solium tapeworms were able to transform steroid precursors to corticosteroids and sex steroids. T. solium tapeworms were recovered from the intestine of golden hamsters that had been orally infected with cysticerci. The worms were cultured in the presence of tritiated progesterone or androstenedione. At the end of the experiments the culture media were analyzed by thin layer chromatography. The experiments described here showed that small amounts of testosterone were synthesized from (3)H-progesterone by complete or segmented tapeworms whereas the incubation of segmented tapeworms with (3)H-androstenedione, instead of (3)H-progesterone, improved their capacity to synthesize testosterone. In addition, the incubation of the parasites with (3)H-progesterone yielded corticosteroids, mainly deoxicorticosterone (DOC) and 11-deoxicortisol. In summary, the results described here, demonstrate that T. solium tapeworms synthesize corticosteroid and sex steroid like metabolites. The capacity of T. solium tapeworms to synthesize steroid hormones may contribute to the physiological functions of the parasite and also to their interaction with the host.

  11. Thermotoga lettingae can salvage cobinamide to synthesize vitamin B12.

    PubMed

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

    2013-11-01

    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 pathway to synthesize B12. In this study, these hypotheses were tested, and we found that Tt. lettingae did not synthesize B12 de novo but salvaged cobinamide. The growth rate of Tt. lettingae increased with the addition of B12 or cobinamide to its medium. It synthesized B12 when the medium was supplemented with cobinamide, and no B12 was detected in cells grown on cobinamide-deficient medium. Upstream of the cobinamide salvage genes is a putative B12 riboswitch. In other organisms, B12 riboswitches allow for higher transcriptional activity in the absence of B12. When Tt. lettingae was grown with no B12, the salvage genes were upregulated compared to cells grown with B12 or cobinamide. Another gene cluster with a putative B12 riboswitch upstream is the btuFCD ABC transporter, and it showed a transcription pattern similar to that of the cobinamide salvage genes. The BtuF proteins from species that can and cannot salvage cobinamides were shown in vitro to bind both B12 and cobinamide. These results suggest that Thermotogales species can use the BtuFCD transporter to import both B12 and cobinamide, even if they cannot salvage cobinamide.

  12. Methods of synthesizing qualitative research studies for health technology assessment.

    PubMed

    Ring, Nicola; Jepson, Ruth; Ritchie, Karen

    2011-10-01

    Synthesizing qualitative research is an important means of ensuring the needs, preferences, and experiences of patients are taken into account by service providers and policy makers, but the range of methods available can appear confusing. This study presents the methods for synthesizing qualitative research most used in health research to-date and, specifically those with a potential role in health technology assessment. To identify reviews conducted using the eight main methods for synthesizing qualitative studies, nine electronic databases were searched using key terms including meta-ethnography and synthesis. A summary table groups the identified reviews by their use of the eight methods, highlighting the methods used most generally and specifically in relation to health technology assessment topics. Although there is debate about how best to identify and quality appraise qualitative research for synthesis, 107 reviews were identified using one of the eight main methods. Four methods (meta-ethnography, meta-study, meta-summary, and thematic synthesis) have been most widely used and have a role within health technology assessment. Meta-ethnography is the leading method for synthesizing qualitative health research. Thematic synthesis is also useful for integrating qualitative and quantitative findings. Four other methods (critical interpretive synthesis, grounded theory synthesis, meta-interpretation, and cross-case analysis) have been under-used in health research and their potential in health technology assessments is currently under-developed. Synthesizing individual qualitative studies has becoming increasingly common in recent years. Although this is still an emerging research discipline such an approach is one means of promoting the patient-centeredness of health technology assessments.

  13. Syntheses and structural studies of coordination polymers with microporous frameworks

    NASA Astrophysics Data System (ADS)

    Niu, Tianyan

    The purpose of this work is to synthesize microporous solids using coordination chemistry. The syntheses were carried by diffusion method. Starting reagents, solvent, concentration, reaction speed and time, and temperature were the variables used to optimize the syntheses. The resulting products were characterized by single crystal X-ray diffraction to determine their structures. X-ray powder diffraction, TGA, IR, elemental analysis, and electron microprobe were used to provide complementary or supporting information. Exploratory studies were carried out mainly on organotin-cyanometalate compounds [(RmSnIV)x{M(CN)n} y]. The compounds are made up of SnRm cations and M(CN) n anions. The structures adopted are determined by the number and size of the organic ligands attached to the Sn atoms and by the cyanometalate M(CN) n moiety. Several new compounds in this class were synthesized and structurally characterized. They are [(Bu3Sn)3M(CN)6] (M = Fe, Co), [(R2Sn)3{CO(CN)6}2·X] (R = vinyl, butyl, and propyl), and [(Ph3Sn)2Ni(CN) 4 Ph3SnOH·˜0.8CH3CN·˜0.2H 2O]. The compound [(Ph3Sn)2Ni(CN)4·Ph 3SnOH·˜0.8CH3CN·˜0.2H2O] is to our knowledge, the first three dimensional cyanometalate coordination polymer with expanded inorganic NbO structure. The framework is not interpenetrated and the large central cavity in the structure is filled by inclusion of Ph 3SnOH and other solvent molecules during synthesis. In addition to the investigation of organotin-cyanometalate compounds, other approaches to microporous solids were also studied. A new compound [Co(H 2O)2Ni(CN)4·4H2O] in the Hofmann's clathrate family was obtained. Five one dimensional polymers synthesized by the reaction of dirhodium(II) tetraacetate with 1,4-dicyanobenzene in different solvent systems were also synthesized, and the effect of solvent on the resulting structures was investigated.

  14. Biological activities of eco-friendly synthesized Hantzsch adducts.

    PubMed

    Pacheco, Samira R; Braga, Taniris C; da Silva, Daniel L; Horta, Livia P; Reis, Fabiano S; Ruiz, Ana Lucia T G; de Carvalho, Joao E; Modolo, Luzia V; de Fatima, Ângelo

    2013-09-01

    Fourteen Hantzsch adducts with different substituents at the C-4 position were synthesized through multicomponent reactions by using citric or lactic acid as catalysts. To the best of our knowledge, this is the first report on the synthesis of such a class of compounds based on multicomponent reactions catalyzed by non-toxic organic acids. The potential to scavenge reactive nitrogen/oxygen species (RNS/ROS) and the ability to inhibit cancer cell growth were then investigated. Among the synthesized compounds, adduct 15 was the most promising free radical scavenger, while adduct 20 was shown to have a wider spectrum of action on the cancer cells studied. These results highlight Hantzsch adducts as lead compounds for obtaining new free radical scavengers and anticancer agents.

  15. Gadolinium doped Ceria nanocrystals synthesized from mesoporous silica

    NASA Astrophysics Data System (ADS)

    Rossinyol, Emma; Pellicer, Eva; Prim, Anna; Estradé, Sònia; Arbiol, Jordi; Peiró, Francesca; Cornet, Albert; Morante, Joan Ramon

    2008-02-01

    Highly crystalline and thermally stable gadolinium doped ceria (GDC) particles have been synthesized by hard template route for the first time. This oxide is being recognized as an intermediate temperature (500-700 °C) electrolyte material for applications in solid-oxide fuel cells. The GDC particles show high crystallinity and nanometric size (2.83 ± 0.05 nm in diameter) and Raman analyses confirm the formation of the solid solution instead of a CeO2 and Gd2O3 mixture. EDX and EELS studies indicate a stoichiometry coherent with the Gd0.2Ce0.8O1.9 phase. The synthesized nanometric powder is expected to be used in solid oxide fuel cells as well as in the catalytic treatment of automobile exhaust fumes.

  16. Ultralight Weight Optical Systems Using Nano-Layered Synthesized Materials

    NASA Technical Reports Server (NTRS)

    Clark, Natalie; Breckinridge, James

    2014-01-01

    Optical imaging is important for many NASA science missions. Even though complex optical systems have advanced, the optics, based on conventional glass and mirrors, require components that are thick, heavy and expensive. As the need for higher performance expands, glass and mirrors are fast approaching the point where they will be too large, heavy and costly for spacecraft, especially small satellite systems. NASA Langley Research Center is developing a wide range of novel nano-layered synthesized materials that enable the development and fabrication of ultralight weight optical device systems that enable many NASA missions to collect science data imagery using small satellites. In addition to significantly reducing weight, the nano-layered synthesized materials offer advantages in performance, size, and cost.

  17. Antibacterial and catalytic activities of green synthesized silver nanoparticles.

    PubMed

    Bindhu, M R; Umadevi, M

    2015-01-25

    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.

  18. Method of synthesizing silica nanofibers using sound waves

    DOEpatents

    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.

  19. Is Ghrelin Synthesized in the Central Nervous System?

    PubMed Central

    Cabral, Agustina; López Soto, Eduardo J.; Epelbaum, Jacques; Perelló, Mario

    2017-01-01

    Ghrelin is an octanoylated peptide that acts via its specific receptor, the growth hormone secretagogue receptor type 1a (GHSR-1a), and regulates a vast variety of physiological functions. It is well established that ghrelin is predominantly synthesized by a distinct population of endocrine cells located within the gastric oxyntic mucosa. In addition, some studies have reported that ghrelin could also be synthesized in some brain regions, such as the hypothalamus. However, evidences of neuronal production of ghrelin have been inconsistent and, as a consequence, it is still as a matter of debate if ghrelin can be centrally produced. Here, we provide a comprehensive review and discussion of the data supporting, or not, the notion that the mammalian central nervous system can synthetize ghrelin. We conclude that no irrefutable and reproducible evidence exists supporting the notion that ghrelin is synthetized, at physiologically relevant levels, in the central nervous system of adult mammals. PMID:28294994

  20. Method of synthesizing silica nanofibers using sound waves

    DOEpatents

    Sharma, Jaswinder K.; Datskos, Panos G.

    2017-08-08

    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.

  1. Characteristics of uranium carbonitride microparticles synthesized using different reaction conditions

    NASA Astrophysics Data System (ADS)

    Silva, Chinthaka M.; Lindemer, Terrence B.; Voit, Stewart R.; Hunt, Rodney D.; Besmann, Theodore M.; Terrani, Kurt A.; Snead, Lance L.

    2014-11-01

    Three sets of experimental conditions were tested to synthesize uranium carbonitride (UC1-xNx) kernels from gel-derived urania-carbon microspheres. Primarily, three sequences of gases were used, N2 to N2-4%H2 to Ar, Ar to N2 to Ar, and Ar-4%H2 to N2-4%H2 to Ar-4%H2. Physical and chemical characteristics such as geometrical density, phase purity, and chemical compositions of the synthesized UC1-xNx were measured. Single-phase kernels were commonly obtained with densities generally ranging from 85% to 93% TD and values of x as high as 0.99. In-depth analysis of the microstrutures of UC1-xNx has been carried out and is discussed with the objective of large batch fabrication of high density UC1-xNx kernels.

  2. Strong nonlinear photonic responses from microbiologically synthesized tellurium nanocomposites

    USGS Publications Warehouse

    Liao, K.-S.; Wang, Jingyuan; Dias, S.; Dewald, J.; Alley, N.J.; Baesman, S.M.; Oremland, R.S.; Blau, W.J.; Curran, S.A.

    2010-01-01

    A new class of nanomaterials, namely microbiologically-formed nanorods composed of elemental tellurium [Te(0)] that forms unusual nanocomposites when combined with poly(m-phenylenevinylene-co-2,5-dioctoxy-phenylenevinylene) (PmPV) is described. These bio-nanocomposites exhibit excellent broadband optical limiting at 532 and 1064 nm. Nonlinear scattering, originating from the laser induced solvent bubbles and microplasmas, is responsible for this nonlinear behavior. The use of bacterially-formed Te(0) when combined with an organic chemical host (e.g., PmPV) is a new green method of nanoparticle syntheses. This opens the possibilities of using unique, biologically synthesized materials to advance future nanoelectronic and nanophotonic applications. ?? 2009 Elsevier B.V. All rights reserved.

  3. Hydrothermally synthesized barium fluoride nanocubes for thermoluminescence dosimetry

    NASA Astrophysics Data System (ADS)

    Bhadane, Mahesh S.; Dahiwale, S. S.; Bhoraskar, V. N.; Dhole, S. D.

    2016-05-01

    In this work, we report a hydrothermally synthesized Dy doped BaF2 (BaF2:Dy) nanocubes and its Thermoluminescence studies. The synthesized BaF2:Dy samples was found to posses FCC structure and having average size ~ 60-70 nm, as revealed through X-Ray Diffraction. Cubical morphology having size ~90 nm was observed from TEM analysis. The 60Co γ- ray irradiated BaF2:Dy TL dosimetric experiments shows a pre-dominant single glow peak at 153 °C, indicating a single level trap present as a metastable state. Furthermore, BaF2:Dy nanophosphor shows a sharp linear response from 10 Gy to 3 kGy, thus it can be applicable as a gamma dosimeter.

  4. Method and apparatus for synthesizing anhydrous HNO.sub.3

    DOEpatents

    Coon, Clifford L.; Harrar, Jackson E.; Pearson, Richard K.; McGuire, Raymond R.

    1984-01-01

    A method and apparatus for electrochemically synthesizing anhydrous HNO.sub.3 from an aqueous solution of HNO.sub.3 includes oxidizing a solution of N.sub.2 O.sub.4 /aqueous HNO.sub.3 at an anode, while maintaining a controlled potential between the N.sub.2 O.sub.4 /aqueous HNO.sub.3 solution and the anode. A potential of about 1.80V vs. SCE is preferred. Anhydrous or aqueous HNO.sub.3 may be disposed at the cathode within the electrochemical cell. Aqueous HNO.sub.3 having a water content of up to about 12% by weight is utilized to synthesize anhydrous HNO.sub.3.

  5. Alumina lightweight ceramics modified with plasma synthesized nanopowders

    NASA Astrophysics Data System (ADS)

    Zake, I.; Svinka, R.; Svinka, V.; Palcevskis, E.

    2011-12-01

    The aim of this study is to clarify possibilities of using plasma synthesized Al2O3 and SiC nanopowders as additives in alumina lightweight ceramics prepared by slip casting. Each plasma synthesized nanopowder (PSNP) was incorporated in the material by a different method, because of their diverse influence on the properties of slip. Al2O3 PSNP was introduced in the matrix in form of aqueous suspension. SiC nanopowder was added directly to raw materials. Bending strength, bulk density, apparent porosity and thermal shock resistance were determined to evaluate the influence of these additives. The effect of Al2O3 PSNP addition on the properties of material depends on the initial sintering temperature. SiC particles during sintering oxidize into SiO2 and then in the reaction with alumina form mullite. Addition of SiC considerably improves bending strength and thermal shock resistance.

  6. Antibacterial and catalytic activities of green synthesized silver nanoparticles

    NASA Astrophysics Data System (ADS)

    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.

  7. Design of optocoupler for synthesizing four color spectra

    NASA Astrophysics Data System (ADS)

    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.

  8. Nanometrology of delignified Populus using mode synthesizing atomic force microscopy

    SciTech Connect

    Tetard, Laurene; Passian, Ali; Farahi, R H; Davison, Brian H; Jung, S; Ragauskas, A J; Lereu, Aude; Thundat, Thomas George

    2011-01-01

    The study of the spatially resolved physical and compositional properties of materials at the nanoscale is increasingly challenging due to the level of complexity of biological specimens such as those of interest in bioenergy production. Mode synthesizing atomic force microscopy (MSAFM) has emerged as a promising metrology tool for such studies. It is shown that, by tuning the mechanical excitation of the probe-sample system, MSAFM can be used to dynamically investigate the multifaceted complexity of plant cells. The results are argued to be of importance both for the characteristics of the invoked synthesized modes and for accessing new features of the samples. As a specific system to investigate, we present images of Populus, before and after a holopulping treatment, a crucial step in the biomass delignification process.

  9. Hydrothermally synthesized barium fluoride nanocubes for thermoluminescence dosimetry

    SciTech Connect

    Bhadane, Mahesh S.; Dahiwale, S. S.; Bhoraskar, V. N.; Dhole, S. D.

    2016-05-23

    In this work, we report a hydrothermally synthesized Dy doped BaF{sub 2} (BaF{sub 2}:Dy) nanocubes and its Thermoluminescence studies. The synthesized BaF{sub 2}:Dy samples was found to posses FCC structure and having average size ~ 60-70 nm, as revealed through X-Ray Diffraction. Cubical morphology having size ~90 nm was observed from TEM analysis. The {sup 60}Co γ- ray irradiated BaF{sub 2}:Dy TL dosimetric experiments shows a pre-dominant single glow peak at 153 °C, indicating a single level trap present as a metastable state. Furthermore, BaF{sub 2}:Dy nanophosphor shows a sharp linear response from 10 Gy to 3 kGy, thus it can be applicable as a gamma dosimeter.

  10. Precision spectroscopy of acetylene transitions using an optical frequency synthesizer.

    PubMed

    Ahtee, V; Merimaa, M; Nyholm, K

    2009-09-01

    An optical frequency synthesizer is used for saturation spectroscopy of acetylene near 1540 nm. In the synthesizer, a user-specified frequency is generated from an atomic time base by phase locking the second harmonic of a cw near-IR external-cavity diode laser (ECDL) to a Ti:sapphire frequency comb. By stepping the repetition rate of the frequency comb, the ECDL frequency is swept over an acetylene transition in a saturated absorption spectroscopy setup. Hence, a spectral lineshape is measured with an absolute frequency scale. Line-center frequencies determined by fitting theoretical line profiles to the measured data are in good agreement with values measured with the ECDL stabilized to acetylene by third-harmonic locking and with the values recommended by the International Committee for Weights and Measures (CIPM).

  11. Syntheses of Octasubstituted Metal Phthalocyanines for Nonlinear Optics

    NASA Technical Reports Server (NTRS)

    Guo, Huaisong; Townsend, Cheryl; Sanghadasa, Mohan; Amai, Robert L. S.; Clark, Ronald D.; Penn, Benjamin

    1998-01-01

    Many organic materials can be used as nonlinear optical media. Phthalocyanines are of special interest because they show an unusually large third order nonlinear response, they are thermally and photochemically stable and they can be formed into oriented thin films (Langmuir-Blodgett films). They also can be easily complexed by a large variety of metals, which place them at the interface between organics and organometallics, and allows for fine tuning of the macro cycle electronic properties by the coordinated metal and substituent groups. A series of 1,4,8,11,15,18,22,25-octaalkoxy metal-free and metal phthalocyanines and 2,3,9,10,16,17,23,24-octaalkoxy metal phthalocyanines has been synthesized. Their nonlinear optical properties have been measured. The physical properties of all the phthalocyanines synthesized in this work are subject to both acid and solvent effects.

  12. Two step continuous method to synthesize colloidal spheroid gold nanorods.

    PubMed

    Chandra, S; Doran, J; McCormack, S J

    2015-12-01

    This research investigated a two-step continuous process to synthesize colloidal suspension of spheroid gold nanorods. In the first step; gold precursor was reduced to seed-like particles in the presence of polyvinylpyrrolidone and ascorbic acid. In continuous second step; silver nitrate and alkaline sodium hydroxide produced various shape and size Au nanoparticles. The shape was manipulated through weight ratio of ascorbic acid to silver nitrate by varying silver nitrate concentration. The specific weight ratio of 1.35-1.75 grew spheroid gold nanorods of aspect ratio ∼1.85 to ∼2.2. Lower weight ratio of 0.5-1.1 formed spherical nanoparticle. The alkaline medium increased the yield of gold nanorods and reduced reaction time at room temperature. The synthesized gold nanorods retained their shape and size in ethanol. The surface plasmon resonance was red shifted by ∼5 nm due to higher refractive index of ethanol than water.

  13. Is Ghrelin Synthesized in the Central Nervous System?

    PubMed

    Cabral, Agustina; López Soto, Eduardo J; Epelbaum, Jacques; Perelló, Mario

    2017-03-15

    Ghrelin is an octanoylated peptide that acts via its specific receptor, the growth hormone secretagogue receptor type 1a (GHSR-1a), and regulates a vast variety of physiological functions. It is well established that ghrelin is predominantly synthesized by a distinct population of endocrine cells located within the gastric oxyntic mucosa. In addition, some studies have reported that ghrelin could also be synthesized in some brain regions, such as the hypothalamus. However, evidences of neuronal production of ghrelin have been inconsistent and, as a consequence, it is still as a matter of debate if ghrelin can be centrally produced. Here, we provide a comprehensive review and discussion of the data supporting, or not, the notion that the mammalian central nervous system can synthetize ghrelin. We conclude that no irrefutable and reproducible evidence exists supporting the notion that ghrelin is synthetized, at physiologically relevant levels, in the central nervous system of adult mammals.

  14. Magnetic properties of cobalt ferrite synthesized by hydrothermal method

    NASA Astrophysics Data System (ADS)

    Allaedini, Ghazaleh; Tasirin, Siti Masrinda; Aminayi, Payam

    2015-05-01

    In this study, the magnetic properties of nanocrystalline cobalt ferrite synthesized via the hydrothermal method have been investigated. The structural properties of the produced powders were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The observed XRD pattern confirmed the spinel/cubic structure of the prepared cobalt ferrite. The SEM pictures show that the simple hydrothermal method produces uniform sphere-shaped nanopowders. Moreover, infrared spectroscopy was used to confirm the formation of cobalt ferrite particles. Magnetic hysteresis was measured using a vibrating sample magnetometer in a maximum field of 10 kOe. The magnetization of the prepared nanoparticles was investigated, and the saturation magnetization ( M s), remanence ( M r), and coercivity ( H c) were derived from the hysteresis loops. The results revealed that the cobalt ferrite nanoparticles synthesized via the simple hydrothermal method exhibit superior magnetic properties.

  15. Total syntheses of Prelactone V and Prelactone B.

    PubMed

    Raghavendra, S; Tadiparthi, Krishnaji; Yadav, J S

    2017-04-10

    The total syntheses of natural products Prelactone-V and Prelactone-B have been accomplished by a novel Chiron approach starting from d-glucose. The synthesis involves isopropylidene acetal formation of d-glucose using Poly(4-vinylpyridine) supported iodine as a catalyst, Tebbe olefination, Grignard reaction, Wittig olefination, selective mono deprotection of acetal using PMA/SiO2, hydrogenation and anti-1,3-diol formation are as key steps.

  16. Method of synthesizing metal doped diamond-like carbon films

    NASA Technical Reports Server (NTRS)

    Ueno, Mayumi (Inventor); Sunkara, Mahendra Kumar (Inventor)

    2003-01-01

    A method of synthesizing metal doped carbon films by placing a substrate in a chamber with a selected amount of a metalorganic compound. An electron cyclotron resonance is applied to the chamber in order to vaporize the metalorganic compound. The resonance is applied to the chamber until a metal doped carbon film is formed. The metalorganic compound is preferably selected from the group consisting of an organic salt of ruthenium, palladium, gold or platinum.

  17. Synthesizing genetic sequential logic circuit with clock pulse generator

    PubMed Central

    2014-01-01

    Background Rhythmic clock widely occurs in biological systems which controls several aspects of cell physiology. For the different cell types, it is supplied with various rhythmic frequencies. How to synthesize a specific clock signal is a preliminary but a necessary step to further development of a biological computer in the future. Results This paper presents a genetic sequential logic circuit with a clock pulse generator based on a synthesized genetic oscillator, which generates a consecutive clock signal whose frequency is an inverse integer multiple to that of the genetic oscillator. An analogous electronic waveform-shaping circuit is constructed by a series of genetic buffers to shape logic high/low levels of an oscillation input in a basic sinusoidal cycle and generate a pulse-width-modulated (PWM) output with various duty cycles. By controlling the threshold level of the genetic buffer, a genetic clock pulse signal with its frequency consistent to the genetic oscillator is synthesized. A synchronous genetic counter circuit based on the topology of the digital sequential logic circuit is triggered by the clock pulse to synthesize the clock signal with an inverse multiple frequency to the genetic oscillator. The function acts like a frequency divider in electronic circuits which plays a key role in the sequential logic circuit with specific operational frequency. Conclusions A cascaded genetic logic circuit generating clock pulse signals is proposed. Based on analogous implement of digital sequential logic circuits, genetic sequential logic circuits can be constructed by the proposed approach to generate various clock signals from an oscillation signal. PMID:24884665

  18. An improved fractional divider for fractional-N frequency synthesizers

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Liu, Yang; Zhou, Yongqi

    2009-07-01

    This paper presents an improved fractional divider used in 1.8~2GHz fractional-N frequency synthesizers. A new clock setting for delta-sigma modulator (DSM) is proposed to prevent the potential problems of traditional fractional dividers: the DSM output would be wrongly loaded and the action of DSM circuit may affect the phase-detection of phase-frequency-detector (PFD). Simulation result shows the effectiveness of this improvement.

  19. Divergent Total Syntheses of Rhodomyrtosones A and B

    PubMed Central

    Gervais, Anais; Lazarski, Kiel E.; Porco, John A.

    2015-01-01

    Herein, we report total syntheses of the tetramethyldihydroxanthene natural product rhodomyrtosone B and the related bis-furan β-triketone natural product rhodomyrtosone A. Nickel-(II)-catalyzed 1,4-conjugate addition of an α-alkylidene-β-dicarbonyl substrate was developed to access the congener rhodomyrtosone B, and oxygenation of the same monoalkylidene derivative followed by cyclization was employed to obtain the bis-furan natural product rhodomyrtosone A. PMID:26351970

  20. Monodispersive CoPt Nanoparticles Synthesized Using Chemical Reduction Method

    NASA Astrophysics Data System (ADS)

    Shen, Cheng-Min; Hui, Chao; Yang, Tian-Zhong; Xiao, Cong-Wen; En, Shu-Tang; Ding, Hao; Gao, Hong-Jun

    2008-04-01

    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 L10 structure and the particles are ferromagnetic at room temperature.

  1. Synthesizing computer generated holograms with reduced number of perspective projections.

    PubMed

    Katz, Barak; Shaked, Natan T; Rosen, Joseph

    2007-10-01

    We present an improved method for recording a synthesized Fourier hologram under incoherent white-light illumination. The advantage of the method is that the number of real projections needed for generating the hologram is significantly reduced. The new method, designated as synthetic projection holography, is demonstrated experimentally. We show that the synthetic projection holography barely affects the reconstructed images. However, by increasing the number of observed projections one can improve the synthetic projection hologram quality.

  2. Multifrequency Aperture-Synthesizing Microwave Radiometer System (MFASMR). Volume 1

    NASA Technical Reports Server (NTRS)

    Wiley, C. A.; Chang, M. U.

    1981-01-01

    Background material and a systems analysis of a multifrequency aperture - synthesizing microwave radiometer system is presented. It was found that the system does not exhibit high performance because much of the available thermal power is not used in the construction of the image and because the image that can be formed has a resolution of only ten lines. An analysis of image reconstruction is given. The system is compared with conventional aperture synthesis systems.

  3. Toward Colloidal Dispersions of Template Synthesized Polypyrrole Nanotubules

    DTIC Science & Technology

    1998-07-01

    membrane and free the template-synthesized nanostructures . For example, we are interested in the idea of assembling (or self-assembling) such...conductive polymer nanostructures into larger superstructures (e.g., grids, oriented films, or long wires). While the polycarbonate template membranes...these nanostructures into a desired ordered superstructure. If, upon dissolution of the membrane, the aggregation process could be prevented, sols of

  4. Experimental and theoretical characterization of a new synthesized extended viologen

    NASA Astrophysics Data System (ADS)

    Alberto, Marta Erminia; De Simone, Bruna Clara; Cospito, Sante; Imbardelli, Daniela; Veltri, Lucia; Chidichimo, Giuseppe; Russo, Nino

    2012-11-01

    A new extended viologen, 4,4'-(2,2'-bithiophene-5,5'-diyl)bis(1-decylpyridinium) triflimide (DTEV2+), has been synthesized and characterized at theoretical and experimental level. Electrochemical and spectroelectrochemical characterization show that this compound undergoes a two-electron reduction mechanism. Density functional computations give insights on the conformational properties of the different reduction species and allow the assignment of the absorption spectra. The agreement between calculated and experimental spectra is quite satisfactory.

  5. A complete algorithm for synthesizing modular fixtures for polygonal parts

    SciTech Connect

    Brost, R.C.; Goldberg, K.Y.

    1993-11-01

    Commercially-available nuclear fixturing systems typically include a square lattice of tapped and bushed holes with precision locating and clamping elements that can be rigidly attached to the lattice using dowel pins or expanding mandrels. Currently, human expertise is required to synthesize a suitable arrangements of these elements to hold a given part. Besides being time consuming, if the set of alternatives is not systematically explored, the designer may fail to find an acceptable fixture or may settle upon a suboptimal fixture. We consider a class of modular fixtures that prevent a part from translating or rotting in the plane using four point contacts on the part`s boundary. These fixtures are based on three round locators, each centered on a lattice point, and one translating clamp. We present an algorithm that accepts a polygonal part shape as input and synthesizes the set of all fixture designs that achieve form closure for the given part. The algorithm also allows the user to specify geometric access constraints on fixtures. If the part has n edges and its maximal diameter is d lattice units, the asymptotic running time of the algorithm is O(n{sup 5}d{sup 5}). We have implemented the algorithm and present example fixtures that it has synthesized. This implementation includes a metric to rank fixtures based on their ability to resist applied forces. We believe this is the first fixture synthesize algorithm that is complete in the sense that it is guaranteed to find an admissible fixture if one exists. Furthermore, the algorithm is guaranteed to find the optimal fixture, relative to any well-defined quality metric.

  6. Thermal Synthesizer System - An integrated approach to spacecraft thermal analysis

    NASA Technical Reports Server (NTRS)

    Panczak, Tim; Fried, Larry; Rickman, Steven; Welch, Mark

    1991-01-01

    The Thermal Synthesizer System (TSS), which is being developed to meet the thermal analysis needs of Space Station Freedom and of the proposed Space Exploration Initiative missions, is examined. The key requirements and design goals to be met by TSS are summarized, and the software engineering and user interface design philosophy are reviewed. The basic architecture for all applications within TSS is described. An overview is given of the main features of each of the applications of TSS.

  7. Ultra-large-scale syntheses of monodisperse nanocrystals

    NASA Astrophysics Data System (ADS)

    Park, Jongnam; An, Kwangjin; Hwang, Yosun; Park, Je-Geun; Noh, Han-Jin; Kim, Jae-Young; Park, Jae-Hoon; Hwang, Nong-Moon; Hyeon, Taeghwan

    2004-12-01

    The development of nanocrystals has been intensively pursued, not only for their fundamental scientific interest, but also for many technological applications. The synthesis of monodisperse nanocrystals (size variation <5%) is of key importance, because the properties of these nanocrystals depend strongly on their dimensions. For example, the colour sharpness of semiconductor nanocrystal-based optical devices is strongly dependent on the uniformity of the nanocrystals, and monodisperse magnetic nanocrystals are critical for the next-generation multi-terabit magnetic storage media. For these monodisperse nanocrystals to be used, an economical mass-production method needs to be developed. Unfortunately, however, in most syntheses reported so far, only sub-gram quantities of monodisperse nanocrystals were produced. Uniform-sized nanocrystals of CdSe (refs 10,11) and Au (refs 12,13) have been produced using colloidal chemical synthetic procedures. In addition, monodisperse magnetic nanocrystals such as Fe (refs 14,15), Co (refs 16-18), γ-Fe2O3 (refs 19,20), and Fe3O4 (refs 21,22) have been synthesized by using various synthetic methods. Here, we report on the ultra-large-scale synthesis of monodisperse nanocrystals using inexpensive and non-toxic metal salts as reactants. We were able to synthesize as much as 40 g of monodisperse nanocrystals in a single reaction, without a size-sorting process. Moreover, the particle size could be controlled simply by varying the experimental conditions. The current synthetic procedure is very general and nanocrystals of many transition metal oxides were successfully synthesized using a very similar procedure.

  8. Adenovirus DNA synthesized in the presence of aphidicolin.

    PubMed Central

    Oguro, M; Yamashita, T; Ariga, H; Nagano, H

    1984-01-01

    Adenovirus types 2 and 5 DNA synthesized in vivo and in vitro in the presence of aphidicolin were studied. Inhibition of adenoviral DNA synthesis by aphidicolin was only 70% even at a concentration of 30 micrograms/ml of aphidicolin, at which the cellular DNA synthesis was completely inhibited. When initiation of the viral DNA synthesis was synchronized with hydroxyurea and labeled with [3H]thymidine for 60 min, the viral DNA synthesized in the presence of 30 micrograms/ml of aphidicolin was not of full length (35 kb) but small (approximately 12 kb) by analysis of alkaline sucrose density gradient centrifugation. When initiation of the viral DNA synthesis was not synchronized, the viral DNAs ranging from full size to 12 kb were synthesized in the presence of aphidicolin, indicating that the nascent DNAs longer than about 12 kb can continue to elongate in the presence of aphidicolin. This 12 kb DNA was not derived from the degradation products of newly synthesized full size adenoviral DNA. The viral DNA synthesis was restored and the full size of adenoviral DNA was attained within 15 min following removal of aphidicolin. About 20% of the entire viral genome length from the 5'-end was not inhibited by aphidicolin, while the synthesis of interior fragments of the adenoviral DNA was markedly inhibited by aphidicolin, judging from the electrophoretic pattern on neutral agarose gel after digestion of DNA with Hind III. These results indicate that aphidicolin inhibits adenoviral DNA replication at the internal region located approximately 20-30% from both terminals. Images PMID:6420772

  9. Synthesized Synchronous Sampling Technique for Bearing Damage Detection Preprint

    DTIC Science & Technology

    2009-03-01

    monitoring of rolling element bearings by the high-frequency resonance technique - a review,” Tribology International 17(1), 3-10, 1984. 2 I. Howard...AFRL-RX-WP-TP-2009-4139 SYNTHESIZED SYNCHRONOUS SAMPLING TECHNIQUE FOR BEARING DAMAGE DETECTION (PREPRINT) Huageng Luo, Hai Qiu...George Ghanime, Melinda Hirz and Geo Van Der Merwe Metals Branch Metals, Ceramics and NDE Division MARCH 2009 Approved for

  10. Activation of catalysts for synthesizing methanol from synthesis gas

    DOEpatents

    Blum, David B.; Gelbein, Abraham P.

    1985-01-01

    A method for activating a methanol synthesis catalyst is disclosed. In this method, the catalyst is slurried in an inert liquid and is activated by a reducing gas stream. The activation step occurs in-situ. That is, it is conducted in the same reactor as is the subsequent step of synthesizing methanol from a methanol gas stream catalyzed by the activated catalyst still dispersed in a slurry.

  11. Bioactive ceramic glasses in situ synthesized by laser melting

    NASA Astrophysics Data System (ADS)

    Taca, Mihaela; Vasile, Eugeniu; Boroica, Lucica; Udrea, Mircea; Medianu, Rares; Munteanu, Maria Cristina

    2008-10-01

    The synthesis of bioactive glass from raw materials even during the laser deposition process, could provide formation of a biocompatible layer on the metallic prosthesis. During the laser irradiation melting and ultrarapid solidification of ceramic materials occur and glasses controlled by the process parameters (especially laser power and solidification rate) will be obtained. The aim of the present paper is to study the influence of the processing parameters on the laser synthesized glasses chemical composition, structure and bioactive behaviour.

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

    SciTech Connect

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

    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.

  13. Antibacterial properties of silver nanoparticles synthesized by marine Ochrobactrum sp.

    PubMed

    Thomas, Roshmi; Janardhanan, Anju; Varghese, Rintu T; Soniya, E V; Mathew, Jyothis; Radhakrishnan, E K

    2014-01-01

    Metal nanoparticle synthesis is an interesting area in nanotechnology due to their remarkable optical, magnetic, electrical, catalytic and biomedical properties, but there needs to develop clean, non-toxic and environmental friendly methods for the synthesis and assembly of nanoparticles. Biological agents in the form of microbes have emerged up as efficient candidates for nanoparticle synthesis due to their extreme versatility to synthesize diverse nanoparticles with varying size and shape. In the present study, an eco favorable method for the biosynthesis of silver nanoparticles using marine bacterial isolate has been attempted. Very interestingly, molecular identification proved it as a strain of Ochrobactrum anhtropi. In addition, the isolate was found to have the potential to form silver nanoparticles intracellularly at room temperature within 24 h. The biosynthesized silver nanoparticles were characterized by UV-Vis spectroscopy, transmission electron microscope (TEM) and scanning electron microscope (SEM). The UV-visible spectrum of the aqueous medium containing silver nanoparticles showed a peak at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. The SEM and TEM micrographs revealed that the synthesized silver nanoparticles were spherical in shape with a size range from 38 nm - 85 nm. The silver nanoparticles synthesized by the isolate were also used to explore its antibacterial potential against pathogens like Salmonella Typhi, Salmonella Paratyphi, Vibrio cholerae and Staphylococcus aureus.

  14. Subnanometer Palladium Particles Synthesized by Atomic Layer Deposition

    SciTech Connect

    Feng, Hao P.; Libera, Joseph A.; Stair, Peter C.; Miller, Jeffrey T.; Elam, Jeffrey W.

    2011-06-03

    Monodispersed palladium nanoparticle catalysts were synthesized by atomic layer deposition (ALD) using alternating exposures of Pd hexafluoroacetylacetonate (Pd(hfac)₂) and formalin on an alumina support. The size of the ALD Pd particles could be tuned by adjusting the preparation conditions. Conventional ALD conditions produced Pd particles with an average size of 1.4 nm. Removal of surface hydroxyls from the alumina support by a chemical treatment using trimethyl aluminum (TMA) before performing Pd ALD led to nanoparticles larger than 2 nm. Ultrasmall (subnanometer) Pd particles were synthesized using low-temperature metal precursor exposures, followed by applying protective ALD alumina overcoats. The ALD Pd particles were characterized by transmission electron microscopy, extended X-ray absorption fine structure, and diffuse reflectance infrared Fourier transform spectroscopy techniques. The Pd loadings were measured by X-ray fluorescence. The catalytic performance of ALD Pd particles of different sizes was compared in the methanol decomposition reaction. The specific activity (normalized by Pd loading) of the ultrasmall Pd particles was higher than those of the larger particles. Considering the metal dispersion factor, the turnover frequency (TOF) of the ultrasmall Pd particles is comparable to that of the medium-sized (1.4 nm, on average) Pd particles synthesized under standard ALD conditions. The large Pd particles (>2 nm) are a factor of 2 less active than the smaller Pd particles.

  15. A novel nanostructure of cadmium oxide synthesized by mechanochemical method

    SciTech Connect

    Tadjarodi, A.; Imani, M.

    2011-11-15

    Highlights: {yields} A novel nanostructure of CdO was synthesized by mechanochemical reaction followed by calcination. {yields} Mechanochemical method is a simple and low-cost to synthesize nanomaterials. {yields} The obtained precursor was characterized by FT-IR, NMR techniques and elemental analysis. {yields} SEM images showed cauliflower-like shape of sample with components average diameter of 68 nm. {yields} The rods and tubes bundles with single crystalline nature were revealed by ED pattern and TEM images. -- Abstract: Cauliflower-like cadmium oxide (CdO) nanostructure was synthesized by mechanochemical reaction followed calcination procedure. Cadmium acetate dihydrate and acetamide were used as reagents and the resulting precursor was calcinated at 450 {sup o}C for 2 h in air. The structures of the precursor and resultant product of the heating treatment were characterized using Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and elemental analysis, X-ray powder diffraction (XRD), energy-dispersive X-ray spectroscopy analysis (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction pattern (ED). SEM and TEM images revealed the cauliflower-like morphology of the sample. This structure includes the bundles of rods and tubes in nanoscale, which combine with each other and form the resulting morphology with the average diameter, 68 nm of the components. ED pattern indicated the single crystal nature of the formed bundles.

  16. A new approach to synthesize supported ruthenium phosphides for hydrodesulfurization

    SciTech Connect

    Wang, Qingfang; Wang, Zhiqiang; Yin, Xiaoqian; Zhou, Linxi; Zhang, Minghui

    2016-02-15

    Highlights: • We bring out a new method to synthesize noble metal phosphides at low temperature. • Both RuP and Ru{sub 2}P were synthesized using triphenylphosphine as phosphorus sources. • Ru{sub 2}P was the better active phase for HDS than RuP and metal Ru. • RuP/SiO{sub 2} prepared by new method had better HDS activity to that by TPR method. - Abstract: Supported noble metal ruthenium phosphides were synthesized by one-step H{sub 2}-thermal treatment method using triphenylphosphine (TPP) as phosphorus sources at low temperatures. Two phosphides RuP and Ru{sub 2}P can be prepared by this method via varying the molar ratio of metal salt and TPP. The as-prepared phosphides were characterized by X-ray powder diffraction (XRD), low-temperature N{sub 2} adsorption, CO chemisorption and transmission electronic microscopy (TEM). The supported ruthenium phosphides prepared by new method and conventional method together with contradistinctive metallic ruthenium were evaluated in hydrodesulfurization (HDS) of dibenzothiophene (DBT). The catalytic results showed that metal-rich Ru{sub 2}P was the better active phase for HDS than RuP and metal Ru. Besides this, ruthenium phosphide catalyst prepared by new method exhibited superior HDS activity to that prepared by conventional method.

  17. A simple method for synthesizing and producing guitar sounds

    NASA Astrophysics Data System (ADS)

    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.

  18. Human keratinocytes synthesize and secrete the extracellular matrix protein, thrombospondin.

    PubMed

    Wikner, N E; Dixit, V M; Frazier, W A; Clark, R A

    1987-02-01

    Thrombospondin (TSP) a glycoprotein originally identified as the endogenous lectin of platelets, is also synthesized by fibroblasts, endothelial cells, pneumocytes, smooth muscle cells, and macrophages. Thrombospondin is subdivided into functional domains which bind specifically to heparin, fibronectin, collagen, and to specific cellular receptors. It is found within the basement membranes of kidney, lung, smooth muscle, and skin. Thus TSP may serve as an important link between cells and matrices. Thrombospondin also has been reported at the epidermal-dermal junction. We wished to determine whether human keratinocytes synthesize and secrete TSP. Pure human keratinocytes were grown in defined medium without fibroblast feeder layers. Immunofluorescent staining with either rabbit polyclonal or mouse monoclonal antibodies to human platelet TSP yielded specific granular staining within the cytoplasm of keratinocytes. Culture media and cellular lysates were harvested from cultures metabolically labeled with [35S]methionine. Trichloroacetic acid precipitation, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and autoradiography revealed a major labeled band comigrating with purified platelet TSP in both the media and the cellular lysates. Immunoprecipitation with either the polyclonal or the monoclonal anti-TSP antibodies followed by SDS-PAGE and autoradiography identified this band as TSP. Thus keratinocytes in culture synthesize and secrete TSP. Thrombospondin may play an important role in epidermal interactions with extracellular matrix.

  19. Antibacterial activity of silver nanoparticles synthesized from serine.

    PubMed

    Jayaprakash, N; Judith Vijaya, J; John Kennedy, L; Priadharsini, K; Palani, P

    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 443nm. The emission spectrum of Ag NPs showed an emission band at 484nm. 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 AgNO3 against Gram-positive and Gram-negative bacteria.

  20. Knowledge Syntheses in Medical Education: Demystifying Scoping Reviews.

    PubMed

    Thomas, Aliki; Lubarsky, Stuart; Durning, Steven J; Young, Meredith E

    2017-02-01

    An unprecedented rise in health professions education (HPE) research has led to increasing attention and interest in knowledge syntheses. There are many different types of knowledge syntheses in common use, including systematic reviews, meta-ethnography, rapid reviews, narrative reviews, and realist reviews. In this Perspective, the authors examine the nature, purpose, value, and appropriate use of one particular method: scoping reviews. Scoping reviews are iterative and flexible and can serve multiple main purposes: to examine the extent, range, and nature of research activity in a given field; to determine the value and appropriateness of undertaking a full systematic review; to summarize and disseminate research findings; and to identify research gaps in the existing literature. Despite the advantages of this methodology, there are concerns that it is a less rigorous and defensible means to synthesize HPE literature. Drawing from published research and from their collective experience with this methodology, the authors present a brief description of scoping reviews, explore the advantages and disadvantages of scoping reviews in the context of HPE, and offer lessons learned and suggestions for colleagues who are considering conducting scoping reviews. Examples of published scoping reviews are provided to illustrate the steps involved in the methodology.

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

    PubMed Central

    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

  2. Antibacterial properties of silver nanoparticles synthesized by marine Ochrobactrum sp

    PubMed Central

    Thomas, Roshmi; Janardhanan, Anju; Varghese, Rintu T.; Soniya, E.V.; Mathew, Jyothis; Radhakrishnan, E.K.

    2014-01-01

    Metal nanoparticle synthesis is an interesting area in nanotechnology due to their remarkable optical, magnetic, electrical, catalytic and biomedical properties, but there needs to develop clean, non-toxic and environmental friendly methods for the synthesis and assembly of nanoparticles. Biological agents in the form of microbes have emerged up as efficient candidates for nanoparticle synthesis due to their extreme versatility to synthesize diverse nanoparticles with varying size and shape. In the present study, an eco favorable method for the biosynthesis of silver nanoparticles using marine bacterial isolate has been attempted. Very interestingly, molecular identification proved it as a strain of Ochrobactrum anhtropi. In addition, the isolate was found to have the potential to form silver nanoparticles intracellularly at room temperature within 24 h. The biosynthesized silver nanoparticles were characterized by UV-Vis spectroscopy, transmission electron microscope (TEM) and scanning electron microscope (SEM). The UV-visible spectrum of the aqueous medium containing silver nanoparticles showed a peak at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. The SEM and TEM micrographs revealed that the synthesized silver nanoparticles were spherical in shape with a size range from 38 nm – 85 nm. The silver nanoparticles synthesized by the isolate were also used to explore its antibacterial potential against pathogens like Salmonella Typhi, Salmonella Paratyphi, Vibrio cholerae and Staphylococcus aureus. PMID:25763025

  3. Development and perceptual assessment of a synthesizer of disordered voices.

    PubMed

    Fraj, Samia; Schoentgen, Jean; Grenez, Francis

    2012-10-01

    A synthesizer is based on a nonlinear wave-shaping model of the glottal area, an algebraic model of the glottal aerodynamics as well as concatenated-tube models of the trachea and vocal tract. Voice disorders are simulated by way of models of vocal frequency jitter and tremor, vocal amplitude shimmer and tremor, as well as pulsatile additive noise. Six experiments have been carried out to assess the synthesizer perceptually. Three experiments involve the perceptual categorization of male synthetic and human stimuli and one the auditory discrimination between synthetic and human tokens. A fifth experiment reports the auditory discrimination between synthetic tokens with different levels of additive and modulation noise. A sixth experiment reports the scoring by expert listeners of male synthetic stimuli on equal-appearing interval scales grade-roughness-breathiness (GRB). A first objective is to demonstrate the ability of the synthesizer to simulate vowel sounds that are valid exemplars of speech sounds produced by humans with voice disorders. A second objective is to learn how human expert raters perceptually map vocal frequency, additive and modulation noise as well as vowel categories into scores on GRB scales.

  4. Characteristics of uranium carbonitride microparticles synthesized using different reaction conditions

    SciTech Connect

    Silva, Chinthaka M; Lindemer, Terrence; Voit, Stewart L; Hunt, Rodney Dale; Besmann, Theodore M; Terrani, Kurt A; Snead, Lance Lewis

    2014-11-01

    Three sets of different experimental conditions by changing the cover gases during the sample preparation were tested to synthesize uranium carbonitride (UC1-xNx) microparticles. In the first two sets of experiments using (N2 to N2-4%H2 to Ar) and (Ar to N2 to Ar) environments, single phase UC1-xNx was synthesized. When reducing environments (Ar-4%H2 to N2-4%H2 to Ar-4%H2) were utilized, theoretical densities up to 97% of single phase UC1-xNx kernels were obtained. Physical and chemical characteristics such as density, phase purity, and chemical compositions of the synthesized UC1-xNx materials for the diferent experimental conditions used are provided. In-depth analysis of the microstrutures of UC1-xNx has been carried out and is discussed with the objective of large batch fabrication of high density UC1-xNx kernels.

  5. The Nature of the Collagen Synthesized by Cultured Human Fibroblasts

    PubMed Central

    Layman, Don L.; McGoodwin, Ermona B.; Martin, George R.

    1971-01-01

    The hydroxyproline-containing proteins (hyproproteins) synthesized by cultured human fibroblasts have been partially characterized. The hyproprotein extracted from the cell layer was found to be similar to the collagen extracted from skin in the ratio of hydroxyproline to proline, chain composition, solubility, and resistance to proteolytic digestion. The hyproproteins isolated from the medium were different. About 20% of the peptide-bound hydroxyproline was found in randomly coiled chains. The α2 chains were present in considerable excess over the α1 chains, suggesting that the α2 chain may be synthesized in quantities greater than required to form a collagen molecule with a chain composition (α1)2α2. The remaining medium hyproprotein appeared to be an unusual form of native collagen which, unlike typical native collagen, was soluble under physiological conditions. This hyproprotein did not yield α chains when denatured and contained material that had a molecular weight greater than α chains. A similar size distribution was observed in the protein synthesized in the presence of β-aminopropionitrile, a specific inhibitor of collagen cross-linking. After treatment with pepsin, typical α1 and α2 chains were obtained from the protein in a 2:1 ratio. Since the medium protein is soluble and has properties different from the typical collagen molecule, it may represent a modified form that functions in the transport of collagen from the cell to the fiber. PMID:5277100

  6. New quinternary selenides: Syntheses, characterizations, and electronic structure calculations

    SciTech Connect

    Chung, Ming-Yan; Lee, Chi-Shen

    2013-06-01

    Five quinternary selenides, Sr₂.₆₃Y₀.₃₇Ge₀.₆₃Sb₂.₃₇Se₈ (I), Sr₂.₆₃La₀.₃₇Ge₀.₆₃Sb₂.₃₇Se₈ (II), Sr₂.₇₁La₀.₂₉Sn₀.₇₇Bi₂.₂₃Se₈ (III), Ba₂.₆₇ La₀.₃₃ Sn₀.₆₇Sb₂.₃₃Se₈ (IV), and Ba₂.₆₇ La₀.₃₃Sn₀.₆₇Bi₂.₃₃Se₈ (V), were synthesized by solid-state reaction in fused silica tubes. These compounds are isostructural and crystallize in the Sr₃GeSb₂Se₈ structural-type, which belongs to the orthorhombic space group Pnma (no. 62). Three structural units, 1[MSe₃], 1[M₄Se₁₀] (M=Tt, Pn) and M´ (M´=groups II and III element), comprise the entire one-dimensional structure, separated by M´. Measurements of electronic resistivity and diffused reflectance suggest that IV and V have semiconducting properties. Electronic structure calculations confirm the site preferences of Sr/La element discovered by crystal structure refinement. - Graphical abstract: Quinternary selenides Ae₂.₆₇M₀.₃₃Tt₀.₆₇Pn₂.₃₃Se₈ (Ae, M, Tt, Pn=Sr/Ba, Y/La, Ge/Sn, Sb/Bi) were synthesized and their site preferences were characterized by single-crystal X-ray diffraction and electronic structure calculation. Highlights: • Five new quinternary selenides were synthesized and characterized. • Structural units, 1[MSe₃] and 1[M₄Se₁₀] (M=Tt, Pn), construct the one-dimensional structure. • Calculations of electronic structure confirm site preference of Sr/La sites.

  7. Engineering an Escherichia coli platform to synthesize designer biodiesels.

    PubMed

    Wierzbicki, Michael; Niraula, Narayan; Yarrabothula, Akshitha; Layton, Donovan S; Trinh, Cong T

    2016-04-20

    Biodiesels, fatty acid esters (FAEs), can be synthesized by condensation of fatty acid acyl CoAs and alcohols via a wax ester synthase in living cells. Biodiesels have advantageous characteristics over petrodiesels such as biodegradability, a higher flash point, and less emission. Controlling fatty acid and alcohol moieties are critical to produce designer biodiesels with desirable physiochemical properties (e.g., high cetane number, low kinematic viscosity, high oxidative stability, and low cloud point). Here, we developed a flexible framework to engineer Escherichia coli cell factories to synthesize designer biodiesels directly from fermentable sugars. In this framework, we designed each FAE pathway as a biodiesel exchangeable production module consisting of acyl CoA, alcohol, and wax ester synthase submodules. By inserting the FAE modules in an engineered E. coli modular chassis cell, we generated E. coli cell factories to produce targeted biodiesels (e.g., fatty acid ethyl (FAEE) and isobutyl (FAIbE) esters) with tunable and controllable short-chain alcohol moieties. The engineered E. coli chassis carrying the FAIbE production module produced 54mg/L FAIbEs with high specificity, accounting for>90% of the total synthesized FAEs and ∼4.7 fold increase in FAIbE production compared to the wildtype. Fed-batch cultures further improved FAIbE production up to 165mg/L. By mixing ethanol and isobutanol submodules, we demonstrated controllable production of mixed FAEEs and FAIbEs. We envision the developed framework offers a flexible, alternative route to engineer designer biodiesels with tunable and controllable properties using biomass-derived fermentable sugars. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Fibronectin synthesized by a human hepatoma cell line

    SciTech Connect

    Glasgow, J.E.; Colman, R.W.

    1984-07-01

    Fibronectin is a family of immunologically similar glycoproteins which mediate a variety of cell-cell and cell-substratum interactions. It is a constituent of the extracellular matrix of connective tissue and circulates in plasma. When suspension and adherent cultures of a human hepatoma cell line (SK-HEP-1) were incubated in serum-free medium, the resulting conditioned medium contained material which was specifically immunoprecipitated by antisera to human plasma fibronectin. By double immunodiffusion, a component in the conditioned culture medium was shown to form a line of identity with fibronectin in human plasma and to migrate as an alpha 2- to beta-globulin during immunoelectrophoresis. Human fibronectin was quantified in conditioned medium by electroimmunodiffusion, and was found to increase for at least three days at about 0.1 micrograms/10(6) cells/day. Adherent cultures of SK-HEP-1 cells were incubated with L-(/sup 35/S)methionine to label newly synthesized proteins. Labeled fibronectin in conditioned medium or in cell extracts comigrated with fibronectin in human plasma as shown by autoradiography following crossed-immunoelectrophoresis. Fibronectin was demonstrated in the extra-cellular matrix of adherent SK-HEP-1 cultures by immunofluorescence. It was shown previously that SK-HEP-1 cells synthesize alpha 1-protease inhibitor, one of the products of normal hepatocytes. The finding that these hepatoma cells also synthesize fibronectin supports the concept that the hepatocyte may be one source of circulating fibronectin, a possibility consistent with the established role of this cell type in blood plasma protein synthesis.

  9. Analyzing and Synthesizing Phylogenies Using Tree Alignment Graphs

    PubMed Central

    Smith, Stephen A.; Brown, Joseph W.; Hinchliff, Cody E.

    2013-01-01

    Phylogenetic trees are used to analyze and visualize evolution. However, trees can be imperfect datatypes when summarizing multiple trees. This is especially problematic when accommodating for biological phenomena such as horizontal gene transfer, incomplete lineage sorting, and hybridization, as well as topological conflict between datasets. Additionally, researchers may want to combine information from sets of trees that have partially overlapping taxon sets. To address the problem of analyzing sets of trees with conflicting relationships and partially overlapping taxon sets, we introduce methods for aligning, synthesizing and analyzing rooted phylogenetic trees within a graph, called a tree alignment graph (TAG). The TAG can be queried and analyzed to explore uncertainty and conflict. It can also be synthesized to construct trees, presenting an alternative to supertrees approaches. We demonstrate these methods with two empirical datasets. In order to explore uncertainty, we constructed a TAG of the bootstrap trees from the Angiosperm Tree of Life project. Analysis of the resulting graph demonstrates that areas of the dataset that are unresolved in majority-rule consensus tree analyses can be understood in more detail within the context of a graph structure, using measures incorporating node degree and adjacency support. As an exercise in synthesis (i.e., summarization of a TAG constructed from the alignment trees), we also construct a TAG consisting of the taxonomy and source trees from a recent comprehensive bird study. We synthesized this graph into a tree that can be reconstructed in a repeatable fashion and where the underlying source information can be updated. The methods presented here are tractable for large scale analyses and serve as a basis for an alternative to consensus tree and supertree methods. Furthermore, the exploration of these graphs can expose structures and patterns within the dataset that are otherwise difficult to observe. PMID:24086118

  10. Laser synthesized nanopowders for polymer-based composites

    NASA Astrophysics Data System (ADS)

    Gavrila-Florescu, Lavinia; Sandu, Ion; Stan, Ana; Dutu, Elena; Voicu, Ion

    2012-09-01

    The paper presents the different laser-synthesized carbon and silicon carbide nanostructures used as fillers for composites with epoxy or phenol resin matrix reinforced with glass or carbon fiber. The effect of nanoadditives on the composites' mechanic and tribologic characteristics is presented. The addition of 2% nanocarbon or 5% SiC has led to the improvement of tensile strength and tensile modulus with 10-15% and 15-20%, respectively. The dry friction coefficient for nanocarbon-containing composites was decreased up to 25% for composites containing nanocarbon, whereas for carbon-carbon composites filled with silicon carbide, this parameter has increased with more than 50%.

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

    SciTech Connect

    Cha, Jennifer N.; Wang, Joseph

    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

  12. Method of synthesizing polymers from a solid electrolyte

    DOEpatents

    Skotheim, Terje A.

    1985-01-01

    A method of synthesizing electrically conductive polymers from a solvent-free solid polymer electrolyte wherein an assembly of a substrate having an electrode thereon, a thin coating of solid electrolyte including a solution of PEO complexed with an alkali salt, and a thin transparent noble metal electrode are disposed in an evacuated chamber into which a selected monomer vapor is introduced while an electric potential is applied across the solid electrolyte to hold the thin transparent electrode at a positive potential relative to the electrode on the substrate, whereby a highly conductive polymer film is grown on the transparent electrode between it and the solid electrolyte.

  13. Method of synthesizing polymers from a solid electrolyte

    DOEpatents

    Skotheim, T.A.

    1984-10-19

    A method of synthesizing electrically conductive polymers from a solvent-free solid polymer electrolyte is disclosed. An assembly of a substrate having an electrode thereon, a thin coating of solid electrolyte including a solution of PEO complexed with an alkali salt, and a thin transparent noble metal electrode are disposed in an evacuated chamber into which a selected monomer vapor is introduced while an electric potential is applied across the solid electrolyte to hold the thin transparent electrode at a positive potential relative to the electrode on the substrate, whereby a highly conductive polymer film is grown on the transparent electrode between it and the solid electrolyte.

  14. Differential processing for frequency chirp measurement using optical pulse synthesizer

    NASA Astrophysics Data System (ADS)

    Kashiwagi, Ken; Seki, Satoshi; Tsuda, Hiroyuki; Takenouchi, Hirokazu; Kurokawa, Takashi

    2017-03-01

    In this study, we introduced an optical pulse synthesizer (OPS) to measure frequency chirps of optical pulses by differential processing. The OPS has a single-chip integrated structure of all elements for the differential filtering and enables stable measurement. Because the exact filter causes a large loss, we employed a phase-only filter, whose frequency response was only in phase. We measured chirp rates of pulses which were induced by propagating standard single mode fibers with different lengths. The retrieved chirp rates were comparable to calculated results. We simulated accuracy of the method and concluded that our experiment had phase control accuracy within 0.07π.

  15. Process for synthesizing titanium carbide, titanium nitride and titanium carbonitride

    DOEpatents

    Koc, R.; Glatzmaier, G.C.

    1995-05-23

    A process is disclosed for synthesizing titanium carbide, titanium nitride or titanium carbonitride. The process comprises placing particles of titanium, a titanium salt or titanium dioxide within a vessel and providing a carbon-containing atmosphere within the vessel. The vessel is heated to a pyrolysis temperature sufficient to pyrolyze the carbon to thereby coat the particles with a carbon coating. Thereafter, the carbon-coated particles are heated in an inert atmosphere to produce titanium carbide, or in a nitrogen atmosphere to produce titanium nitride or titanium carbonitride, with the heating being of a temperature and time sufficient to produce a substantially complete solid solution.

  16. Process for synthesizing titanium carbide, titanium nitride and titanium carbonitride

    DOEpatents

    Koc, Rasit; Glatzmaier, Gregory C.

    1995-01-01

    A process for synthesizing titanium carbide, titanium nitride or titanium carbonitride. The process comprises placing particles of titanium, a titanium salt or titanium dioxide within a vessel and providing a carbon-containing atmosphere within the vessel. The vessel is heated to a pyrolysis temperature sufficient to pyrolyze the carbon to thereby coat the particles with a carbon coating. Thereafter, the carbon-coated particles are heated in an inert atmosphere to produce titanium carbide, or in a nitrogen atmosphere to produce titanium nitride or titanium carbonitride, with the heating being of a temperature and time sufficient to produce a substantially complete solid solution.

  17. Methods to Design and Synthesize Antibody-Drug Conjugates (ADCs)

    PubMed Central

    Yao, Houzong; Jiang, Feng; Lu, Aiping; Zhang, Ge

    2016-01-01

    Antibody-drug conjugates (ADCs) have become a promising targeted therapy strategy that combines the specificity, favorable pharmacokinetics and biodistributions of antibodies with the destructive potential of highly potent drugs. One of the biggest challenges in the development of ADCs is the application of suitable linkers for conjugating drugs to antibodies. Recently, the design and synthesis of linkers are making great progress. In this review, we present the methods that are currently used to synthesize antibody-drug conjugates by using thiols, amines, alcohols, aldehydes and azides. PMID:26848651

  18. Process for synthesizing compounds from elemental powders and product

    DOEpatents

    Rabin, Barry H.; Wright, Richard N.

    1993-01-01

    A process for synthesizing intermetallic compounds from elemental powders. The elemental powders are initially combined in a ratio which approximates the stoichiometric composition of the intermetallic compound. The mixed powders are then formed into a compact which is heat treated at a controlled rate of heating such that an exothermic reaction between the elements is initiated. The heat treatment may be performed under controlled conditions ranging from a vacuum (pressureless sintering) to compression (hot pressing) to produce a desired densification of the intermetallic compound. In a preferred form of the invention, elemental powders of Fe and Al are combined to form aluminide compounds of Fe.sub.3 Al and FeAl.

  19. Simulating and Synthesizing Substructures Using Neural Network and Genetic Algorithms

    NASA Technical Reports Server (NTRS)

    Liu, Youhua; Kapania, Rakesh K.; VanLandingham, Hugh F.

    1997-01-01

    The feasibility of simulating and synthesizing substructures by computational neural network models is illustrated by investigating a statically indeterminate beam, using both a 1-D and a 2-D plane stress modelling. The beam can be decomposed into two cantilevers with free-end loads. By training neural networks to simulate the cantilever responses to different loads, the original beam problem can be solved as a match-up between two subsystems under compatible interface conditions. The genetic algorithms are successfully used to solve the match-up problem. Simulated results are found in good agreement with the analytical or FEM solutions.

  20. Comparative sinterability of combustion synthesized and commercial titanium carbides

    SciTech Connect

    Manley, B.W.

    1984-11-01

    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 1600/sup 0/C. 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.

  1. Scalable syntheses of the BET bromodomain inhibitor JQ1.

    PubMed

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

    2015-06-03

    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.

  2. Size evolution of ion beam synthesized Pb nanoparticles in Al

    PubMed Central

    2014-01-01

    The size evolution of Pb nanoparticles (NPs) synthesized by ion implantation in an epitaxial Al film has been experimentally investigated. The average radius R of Pb NPs was determined as a function of implantation fluence f. The R(f) data were analyzed using various growth models. Our observations suggest that the size evolution of Pb NPs is controlled by the diffusion-limited growth kinetics (R2∝f). With increasing implantation current density, the diffusion coefficient of Pb atoms in Al is evident to be enhanced. By a comparative analysis of the R(f) data, values of the diffusion coefficient of Pb in Al were obtained. PMID:25114640

  3. Flavonoid Properties in Plant Families Synthesizing Betalain Pigments (Review).

    PubMed

    Iwashina, Tsukasa

    2015-06-01

    The anthocyanin pigments are contained in the flowers, fruits, leaves and roots of almost plant species. On the other hand, distribution of the betacyanins are limited in eight families of the order Caryophyllales, i.e. Aizoaceae, Amaranthaceae, Basellaceae, Cactaceae, Didiereaceae, Nyctaginaceae, Phytolaccaceae and Portulacaceae. However, other flavonoids, i.e. flavones, C-glycosylflavones, flavonols, flavanones, dihydroflavonols, chalcones, aurones, and flavan and proanthocyanidins, are synthesized in betalain-containing families. In this review, distribution and properties of the flavonoids in eight betalain-containing families are described.

  4. Asymmetric Total Syntheses of Megacerotonic Acid and Shimobashiric Acid A

    PubMed Central

    Krabbe, Scott W.; Johnson, Jeffrey S.

    2015-01-01

    The asymmetric total syntheses of the α-benzylidene-γ-butyrolactone natural products megacerotonic acid and shimobashiric acid A have been accomplished in nine and 11 steps, respectively, from simple, commercially available starting materials. The key step for each synthesis is the (arene)RuCl(monosulfonamide)-catalyzed dynamic kinetic resolution-asymmetric transfer hydrogenation (DKR-ATH) of racemic α,δ-diketo-β-aryl esters to establish the absolute stereochemistry. Intramolecular diastereoselective Dieckmann cyclization forms the lactone core, and ketone reduction/alcohol elimination installs the α-arylidene. PMID:25699999

  5. Divergent Total Syntheses of (−)-Aspidospermine and (+)-Spegazzinine

    PubMed Central

    Lajiness, James P.; Jiang, Wanlong; Boger, Dale L.

    2012-01-01

    Divergent total syntheses of (+)-spegazzinine (1) and (−)-aspidospermine (2) and their extensions to the synthesis of C19-epi-aspidospermine and C3-epi-spegazzinine are detailed, confirming the relative stereochemistry and establishing the absolute configuration of (+)-spegazzinine. A powerful intramolecular [4 + 2]/[3 + 2] cycloaddition cascade of a 1,3,4-oxadiazole provided the pentacyclic skeleton and all the requisite stereochemistry of the natural products in a single reaction that forms three rings, four C–C bonds, and five stereocenters. PMID:22480368

  6. Syntheses of 4,6'-epoxymorphinan derivatives and their pharmacologies.

    PubMed

    Nemoto, Toru; Fujii, Hideaki; Narita, Minoru; Miyoshi, Kan; Nakamura, Atsushi; Suzuki, Tsutomu; Nagase, Hiroshi

    2008-04-15

    A modification of the message site in the skeleton of naltrexone was carried out to improve the potency and selectivity of the compound for an opioid receptor subtype. In the course of conversion, we synthesized 7-membered ring ether derivatives, which had an inserted OCH(2) group between 4- and 6-positions of morphinan skeleton. One of the 7-membered ring ether derivatives possessed more potent antagonistic activity than naltrexone for the mu opioid receptor. Another compound possessing 17-methyl group derived from noroxycodone may be a mu opioid receptor partial agonist and showed analgesic activity. We are currently examining the subtype selectivity of these compounds.

  7. Novel penicillins synthesized by biotransformation using laccase from Trametes spec.

    PubMed

    Mikolasch, Annett; Niedermeyer, Timo Horst Johannes; Lalk, Michael; Witt, Sabine; Seefeldt, Simone; Hammer, Elke; Schauer, Frieder; Gesell, Manuela; Hessel, Susanne; Jülich, Wolf-Dieter; Lindequist, Ulrike

    2006-05-01

    Eight novel penicillins were synthesized by heteromolecular reaction of ampicillin or amoxicillin with 2,5-dihydroxybenzoic acid derivatives using a laccase from Trametes spec. All products inhibited the growth of several gram positive bacterial strains in the agar diffusion assay, among them methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci. The products protected mice against an infection with Staphylococcus aureus lethal to the untreated animals. Cytotoxicity and acute toxicity of the new compounds were neglectable. The results show the usefulness of laccase for the synthesis of potential new antibiotics. The biological activity of the new compounds stimulates intensified pharmacological tests.

  8. Sensitized photoluminescence of erbium silicate synthesized on porous silicon framework

    NASA Astrophysics Data System (ADS)

    Shen, Hao; Xu, Lingbo; Li, Dongsheng; Yang, Deren

    2017-09-01

    Er silicate/porous silicon (PS) composites with effective sensitized erbium emission at 1.53 μm have been synthesized on the PS framework. Cross-sectional scanning electron microscopy and X-ray diffraction reveal that the PS is coated by Er silicate in composites. Indirect excitation of Er3+ ion luminescence via energy transfer from PS is confirmed. The temperature dependence of Er-related photoluminescence intensity and lifetime is investigated, which concludes a phonon-mediated energy transfer process. The combination of the PS framework and Er silicate provides a possible strategy for practical silicon-based light sources.

  9. A facile route to synthesize nanogels doped with silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Coll Ferrer, M. Carme; Ferrier, Robert C.; Eckmann, David M.; Composto, Russell J.

    2013-01-01

    In this study, we describe a simple method to prepare hybrid nanogels consisting of a biocompatible core-shell polymer host containing silver nanoparticles. First, the nanogels (NG, 160 nm) containing a lysozyme rich core and a dextran rich shell, are prepared via Maillard and heat-gelation reactions. Second, silver nanoparticles (Ag NPs, 5 nm) are synthesized "in situ" in the NG solution without requiring additional reducing agents. This approach leads to stable Ag NPs located in the NG. Furthermore, we demonstrate that the amount of Ag NPs in the NG can be tuned by varying silver precursor concentration. Hybrid nanogels with silver nanoparticles have potential in antimicrobial, optical, and therapeutic applications.

  10. Synthesizing aluminum particles towards controlling electrostatic discharge ignition sensitivity

    SciTech Connect

    Eric S. Collins; Jeffery P. Gesner; Michelle L. Pantoya; Michael A. Daniels

    2014-02-01

    Aluminum particles were synthesized with shell thicknesses ranging from 2.7 to 8.3 nm and a constant diameter of 95 nm. These fuel particles were combined with molybdenum trioxide particles and the electrostatic discharge (ESD) sensitivity of the mixture was measured. Results show ignition delay increased as the alumina shell thickness increased. These results correlated with electrical resistivity measurements of the mixture which increased with alumina concentration. A model was developed using COMSOL for ignition of a single Al particle. The ignition delay in the model was consistent with the experimental results suggesting that the primary ESD ignition mechanism is joule heating.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Kinetics of synthesizing polymer-supported quaternary ammonium catalysts.

    PubMed

    Wu, Ho-Shing; Lo, Chi-Wei

    2006-01-01

    This study attempted to synthesize the optimum quaterary ammonium poly(styrene-co-methylstyrene) catalyst using the combinatorial chemistry method. The catalyst was synthesized by a mix-split method. A phase-transfer catalyst library with 25 kinds of polystyrene-supported quaternary ammonium salt catalyst was the the result of the reaction of five kinds of chloromethylated crosslinked polystyrene with five tert-amines. The allylation of phenol and the oxidation of benzyl alcohol were used as the probing reaction to screen out the most active catalyst for the reaction using the iterative deconvolution method. The screening conditions included teritary amine and organic solvent. The structure of the most active catalyst in the allylation of phenol shows 20 mol % ring substitution and 0.177-0.25-mm pellet size activated with trihexylamine. For oxidation of benzyl alcohol, the reaction conditions of the most active catalyst included a resin of 20% ring substitution and pellet size of 0.177-0.25 mm, activated with triethylamine reacting in an organic solvent of n-hexane.

  13. Peptide-templated noble metal catalysts: syntheses and applications.

    PubMed

    Wang, Wei; Anderson, Caleb F; Wang, Zongyuan; Wu, Wei; Cui, Honggang; Liu, Chang-Jun

    2017-05-01

    Noble metal catalysts have been widely used in many applications because of their high activity and selectivity. However, a controllable preparation of noble metal catalysts still remains as a significant challenge. To overcome this challenge, peptide templates can play a critical role in the controllable syntheses of catalysts owing to their flexible binding with specific metallic surfaces and self-assembly characteristics. By employing peptide templates, the size, shape, facet, structure, and composition of obtained catalysts can all be specifically controlled under the mild synthesis conditions. In addition, catalysts with spherical, nanofiber, and nanofilm structures can all be produced by associating with the self-assembly characteristics of peptide templates. Furthermore, the peptide-templated noble metal catalysts also reveal significantly enhanced catalytic behaviours compared with conventional catalysts because the electron conductivity, metal dispersion, and reactive site exposure can all be improved. In this review, we summarize the research progresses in the syntheses of peptide-templated noble metal catalysts. The applications of the peptide-templated catalysts in organic reactions, photocatalysis, and electrocatalysis are discussed, and the relationship between structure and activity of these catalysts are addressed. Future opportunities, including new catalytic materials designed by using biological principles, are indicated to achieve selective, eco-friendly, and energy neutral synthesis approaches.

  14. Protein immobilization onto electrochemically synthesized CoFe nanowires

    PubMed Central

    Torati, Sri Ramulu; Reddy, Venu; Yoon, Seok Soo; Kim, CheolGi

    2015-01-01

    CoFe nanowires have been synthesized by the electrodeposition technique into the pores of a polycarbonate membrane with a nominal pore diameter of 50 nm, and the composition of CoFe nanowires varying by changing the source concentration of iron. The synthesized nanowire surfaces were functionalized with amine groups by treatment with aminopropyltriethoxysilane (APTES) linker, and then conjugated with streptavidin-Cy3 protein via ethyl (dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide coupling chemistry. The oxide surface of CoFe nanowire is easily modified with aminopropyltriethoxysilane to form an amine terminating group, which is covalently bonded to streptavidin-Cy3 protein. The physicochemical properties of the nanowires were analyzed through different characterization techniques such as scanning electron microscope, energy dispersive spectroscopy, and vibrating sample magnetometer. Fluorescence microscopic studies and Fourier transform infrared studies confirmed the immobilization of protein on the nanowire surface. In addition, the transmission electron microscope analysis reveals the thin protein layer which is around 12–15 nm on the nanowire surfaces. PMID:25609966

  15. A simple route to synthesize manganese germanate nanorods

    SciTech Connect

    Pei, L.Z. Yang, Y.; Yuan, C.Z.; Duan Taike; Zhang Qianfeng

    2011-06-15

    Manganese germanate nanorods have been synthesized by a simple route using germanium dioxide and manganese acetate as the source materials. X-ray diffraction observation shows that the nanorods are composed of orthorhombic and monoclinic manganese germanate phases. Scanning electron microscopy and transmission electron microscopy observations display that the manganese germanate nanorods have flat tips with the length of longer than 10 micrometers and diameter of 60-350 nm, respectively. The role of the growth conditions on the formation of the manganese germanate nanorods shows that the proper selection and combination of the growth conditions are the key factor for controlling the formation of the manganese germanate nanorods. The photoluminescence spectrum of the manganese germanate nanorods exhibits four fluorescence emission peaks centered at 422 nm, 472 nm, 487 nm and 530 nm showing the application potential for the optical devices. - Research Highlights: {yields} Manganese germanate nanorods have been synthesized by simple hydrothermal process. {yields} The formation of manganese germanate nanorods can be controlled by growth conditions. {yields} Manganese germanate nanorods exhibit good PL emission ability for optical device.

  16. Thermally Stable Mesoporous Silica Spheres synthesized under Mild Conditions

    NASA Astrophysics Data System (ADS)

    Ziegler, Christopher; You, Eunyoung; Watkins, James

    2009-03-01

    Thermally stable, mesoporous silica spheres were synthesized using a one-pot technique under mild conditions. As-calcined silica spheres were shown to be highly porous with surface areas greater than 1000 m^2/g and pore volumes on the order of 1 cc/g. Pore walls were found to be highly resistant to collapse as a consequence of thermal treatment at temperatures exceeding 750 C or hydrothermal treatment in boiling water at temperatures exceeding 100 C for over 100 hours. ^29Si-^1H cross polarization NMR data indicate that the silica is highly condensed at the surface providing rationale for the exceptional pore wall stability observed. The mesoporous silica spheres were synthesized from tetraethyl orthosilicate (TEOS) at room temperature and near-neutral pH using cysteamine and cetyltrimethylammonium bromide (CTAB) in a mixed water and ethanol system. Sphere size was shown to be tunable by altering the relative amounts of ethanol, CTAB, or TEOS. Sphere diameters ranging from 30 nm to 560 nm were observed. The preparation method and characterization of these highly condensed, thermally stable, mesoporous silica spheres for applications including sensing, catalysis, purification, and payload encapsulation is presented.

  17. Synthesized voice approach callouts for air transport operations

    NASA Technical Reports Server (NTRS)

    Simpson, C. A.

    1980-01-01

    A flight simulation experiment was performed to determine the effectiveness of synthesized voice approach callouts for air transport operations. Flight deck data was first collected on scheduled air carrier operations to describe existing pilot-not-flying callout procedures in the flight context and to document the types and amounts of other auditory cockpit information during different types of air carrier operations. A flight simulation scenario for a wide-body jet transport airline training simulator was developed in collaboration with a major U.S. air carrier and flown by three-man crews of qualified line pilots as part of their normally scheduled recurrent training. Each crew flew half their approaches using the experimental synthesized voice approach callout system (SYNCALL) and the other half using the company pilot-not-flying approach callout procedures (PNF). Airspeed and sink rate performance was better with the SYNCALL system than with the PNF system for non-precision approaches. For the one-engine approach, for which SYNCALL made inappropriate deviation callouts, airspeed performance was worse with SYNCALL than with PNF. Reliability of normal altitude approach callouts was comparable for PNF on the line and in the simulator and for SYNCALL in the simulator.

  18. Fast synthesize ZnO quantum dots via ultrasonic method.

    PubMed

    Yang, Weimin; Zhang, Bing; Ding, Nan; Ding, Wenhao; Wang, Lixi; Yu, Mingxun; Zhang, Qitu

    2016-05-01

    Green emission ZnO quantum dots were synthesized by an ultrasonic sol-gel method. The ZnO quantum dots were synthesized in various ultrasonic temperature and time. Photoluminescence properties of these ZnO quantum dots were measured. Time-resolved photoluminescence decay spectra were also taken to discover the change of defects amount during the reaction. Both ultrasonic temperature and time could affect the type and amount of defects in ZnO quantum dots. Total defects of ZnO quantum dots decreased with the increasing of ultrasonic temperature and time. The dangling bonds defects disappeared faster than the optical defects. Types of optical defects first changed from oxygen interstitial defects to oxygen vacancy and zinc interstitial defects. Then transformed back to oxygen interstitial defects again. The sizes of ZnO quantum dots would be controlled by both ultrasonic temperature and time as well. That is, with the increasing of ultrasonic temperature and time, the sizes of ZnO quantum dots first decreased then increased. Moreover, concentrated raw materials solution brought larger sizes and more optical defects of ZnO quantum dots. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Discrimination of synthesized English vowels by American and Korean listeners

    NASA Astrophysics Data System (ADS)

    Yang, Byunggon

    2004-05-01

    This study explored the discrimination of synthesized English vowel pairs by 27 American and Korean, male and female listeners. The average formant values of nine monophthongs produced by ten American English male speakers were employed to synthesize the vowels. Then, subjects were instructed explicitly to respond to AX discrimination tasks in which the standard vowel was followed by another one with the increment or decrement of the original formant values. The highest and lowest formant values of the same vowel quality were collected and compared to examine patterns of vowel discrimination. Results showed that the American and Korean groups discriminated the vowel pairs almost identically and their center formant frequency values of the high and low boundary fell almost exactly on those of the standards. In addition, the acceptable range of the same vowel quality was similar among the language and gender groups. The acceptable thresholds of each vowel formed an oval to maintain perceptual contrast from adjacent vowels. Pedagogical implications of those findings are discussed.

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Microstructural Properties of Chemically Synthesized Cubic ZnS Nanocrystals

    NASA Astrophysics Data System (ADS)

    Deka, Kuldeep; Kalita, M. P. C.

    2015-02-01

    In this paper we present microstructural properties of chemically synthesized cubic zinc sulfide (ZnS) nanocrystals, investigated by X-ray diffraction (XRD) line profile analysis applying classical Williamson-Hall (WH) and modified Williamson-Hall (MWH) methods, and transmission electron microscopy (TEM) observations. ZnS nanocrystals are synthesized using 1:1 M ratio of Zn and S precursors with 25, 50, and 75 mM, 2-mercaptoethanol as capping agent. WH analyses show that the average crystallite sizes (lattice strain) are 3.98 nm (2.22 × 10-2), 2.69 nm (1.99 × 10-2), and 2.58 nm (2.65 × 10-2). Dislocation contrast factors of ZnS crystals required for the MWH method are calculated from their elastic stiffness constants for various proportions of screw and edge dislocations. The best fit to MWH equation is found to be for dislocation contrast factors corresponding to 100 % edge dislocations and thereby suggesting edge dislocations are main contributors to strain. MWH analyses show dislocation density of 3.65, 2.69, and 2.47 nm crystallites are 3.19 × 1018 m-2, 2.58 × 1018 m-2, and 4.62 × 1018 m-2 , respectively. The crystallite sizes as estimated from the WH, MWH, and TEM studies are found to be intercorrelated. Presence of edge dislocations, as suggested by the MWH analysis, is confirmed by high resolution TEM (HRTEM) studies.

  2. A high-power synthesized ultrawideband radiation source

    NASA Astrophysics Data System (ADS)

    Efremov, A. M.; Koshelev, V. I.; Plisko, V. V.; Sevostyanov, E. A.

    2017-09-01

    A high-power ultrawideband radiation source has been developed which is capable of synthesizing electromagnetic pulses with different frequency bands in free space. To this end, a new circuit design comprising a four-channel former of bipolar pulses of durations 2 and 3 ns has been elaborated and conditions for the stable operation of gas gaps of independent channels without external control pulses have been determined. Each element of the 2 × 2 array of combined antennas is driven from an individual channel of the pulse former. Antennas excited by pulses of the same duration are arranged diagonally. Two radiation synthesis modes have been examined: one aimed to attain ultimate field strength and the other aimed to attain an ultimate width of the radiation spectrum. The modes were changed by changing the time delay between the 2-ns and 3-ns pulses. For the first mode, radiation pulses with a frequency band of 0.2-0.8 GHz and an effective potential of 500 kV have been obtained. The synthesized radiation pulses produced in the second mode had an extended frequency band (0.1-1 GHz) and an effective potential of 220 kV. The pulse repetition frequency was 100 Hz.

  3. Protein immobilization onto electrochemically synthesized CoFe nanowires.

    PubMed

    Torati, Sri Ramulu; Reddy, Venu; Yoon, Seok Soo; Kim, CheolGi

    2015-01-01

    CoFe nanowires have been synthesized by the electrodeposition technique into the pores of a polycarbonate membrane with a nominal pore diameter of 50 nm, and the composition of CoFe nanowires varying by changing the source concentration of iron. The synthesized nanowire surfaces were functionalized with amine groups by treatment with aminopropyltriethoxysilane (APTES) linker, and then conjugated with streptavidin-Cy3 protein via ethyl (dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide coupling chemistry. The oxide surface of CoFe nanowire is easily modified with aminopropyltriethoxysilane to form an amine terminating group, which is covalently bonded to streptavidin-Cy3 protein. The physicochemical properties of the nanowires were analyzed through different characterization techniques such as scanning electron microscope, energy dispersive spectroscopy, and vibrating sample magnetometer. Fluorescence microscopic studies and Fourier transform infrared studies confirmed the immobilization of protein on the nanowire surface. In addition, the transmission electron microscope analysis reveals the thin protein layer which is around 12-15 nm on the nanowire surfaces.

  4. Magnetic properties of bio-synthesized zinc ferrite nanoparticles

    SciTech Connect

    Yeary, Lucas W; Moon, Ji Won; Rawn, Claudia J; Love, Lonnie J; Rondinone, Adam Justin; Thompson, James R; Chakoumakos, Bryan C; Phelps, Tommy Joe

    2011-01-01

    The magnetic properties of zinc ferrite (Zn-substituted magnetite, Zn{sub y}Fe{sub 1-y}Fe{sub 2}O{sub 4}) formed by a microbial process compared favorably with chemically synthesized materials. A metal reducing bacterium, Thermoanaerobacter, strain TOR-39 was incubated with Zn{sub x}Fe{sub 1-x}OOH (x=0.01, 0.1, and 0.15) precursors and produced nanoparticulate zinc ferrites. Composition and crystalline structure of the resulting zinc ferrites were verified using X-ray fluorescence, X-ray diffraction, transmission electron microscopy, and neutron diffraction. The average composition from triplicates gave a value for y of 0.02, 0.23, and 0.30 with the greatest standard deviation of 0.02. Average crystallite sizes were determined to be 67, 49, and 25 nm, respectively. While crystallite size decreased with more Zn substitution, the lattice parameter and the unit cell volume showed a gradual increase in agreement with previous literature values. The magnetic properties were characterized using a superconducting quantum interference device magnetometer and were compared with values for the saturation magnetization (M{sub s}) reported in the literature. The averaged M{sub s} values for the triplicates with the largest amount of zinc (y=0.30) gave values of 100.1, 96.5, and 69.7 emu/g at temperatures of 5, 80, and 300 K, respectively indicating increased magnetic properties of the bacterially synthesized zinc ferrites.

  5. Boron Nitride Nanotubes Synthesized by Pressurized Reactive Milling Process

    NASA Technical Reports Server (NTRS)

    Hurst, Janet B.

    2004-01-01

    Nanotubes, because of their very high strength, are attractive as reinforcement materials for ceramic matrix composites (CMCs). Recently there has been considerable interest in developing and applying carbon nanotubes for both electronic and structural applications. Although carbon nanotubes can be used to reinforce composites, they oxidize at high temperatures and, therefore, may not be suitable for ceramic composites. Boron nitride, because it has a higher oxidation resistance than carbon, could be a potential reinforcement material for ceramic composites. Although boron nitride nanotubes (BNnT) are known to be structurally similar to carbon nanotubes, they have not undergone the same extensive scrutiny that carbon nanotubes have experienced in recent years. This has been due to the difficulty in synthesizing this material rather than lack of interest in the material. We expect that BNnTs will maintain the high strength of carbon nanotubes while offering superior performance for the high-temperature and/or corrosive applications of interest to NASA. At the NASA Glenn Research of preparing BN-nTs were investigated and compared. These include the arc jet process, the reactive milling process, and chemical vapor deposition. The most successful was a pressurized reactive milling process that synthesizes BN-nTs of reasonable quantities.

  6. Evolutionary selection of enzymatically synthesized semiconductors from biomimetic mineralization vesicles

    SciTech Connect

    Bawazer, Lukmaan A.; Izumi, Michi; Kolodin, Dmitriy; Neilson, James R.; Schwenzer, Birgit; Morse, Daniel E.

    2012-10-29

    The way nature evolves and sculpts materials using proteins inspires new approaches to materials engineering but is still not completely understood. Here, we present a cell-free synthetic biological platform to advance studies of biologically synthesized solid-state materials. This platform is capable of simultaneously exerting many of the hierarchical levels of control found in natural biomineralization, including genetic, chemical, spatial, structural, and morphological control, while supporting the evolutionary selection of new mineralizing proteins and the corresponding genetically encoded materials that they produce. DNA-directed protein expression and enzymatic mineralization occur on polystyrene microbeads in water-in-oil emulsions, yielding synthetic surrogates of biomineralizing cells that are then screened by flow sorting, with light-scattering signals used to sort the resulting mineralized composites differentially. We demonstrate the utility of this platform by evolutionarily selecting newly identified silicateins, biomineralizing enzymes previously identified from the silica skeleton of a marine sponge, for enzyme variants capable of synthesizing silicon dioxide (silica) or titanium dioxide (titania) composites. Mineral composites of intermediate strength are preferentially selected to remain intact for identification during cell sorting, and then to collapse postsorting to expose the encoding genes for enzymatic DNA amplification. Some of the newly selected silicatein variants catalyze the formation of crystalline silicates, whereas the parent silicateins lack this ability. The demonstrated bioengineered route to previously undescribed materials introduces in vitro enzyme selection as a viable strategy for mimicking genetic evolution of materials as it occurs in nature.

  7. Peptide-templated noble metal catalysts: syntheses and applications

    PubMed Central

    Wang, Wei; Anderson, Caleb F.; Wang, Zongyuan; Wu, Wei

    2017-01-01

    Noble metal catalysts have been widely used in many applications because of their high activity and selectivity. However, a controllable preparation of noble metal catalysts still remains as a significant challenge. To overcome this challenge, peptide templates can play a critical role in the controllable syntheses of catalysts owing to their flexible binding with specific metallic surfaces and self-assembly characteristics. By employing peptide templates, the size, shape, facet, structure, and composition of obtained catalysts can all be specifically controlled under the mild synthesis conditions. In addition, catalysts with spherical, nanofiber, and nanofilm structures can all be produced by associating with the self-assembly characteristics of peptide templates. Furthermore, the peptide-templated noble metal catalysts also reveal significantly enhanced catalytic behaviours compared with conventional catalysts because the electron conductivity, metal dispersion, and reactive site exposure can all be improved. In this review, we summarize the research progresses in the syntheses of peptide-templated noble metal catalysts. The applications of the peptide-templated catalysts in organic reactions, photocatalysis, and electrocatalysis are discussed, and the relationship between structure and activity of these catalysts are addressed. Future opportunities, including new catalytic materials designed by using biological principles, are indicated to achieve selective, eco-friendly, and energy neutral synthesis approaches. PMID:28507701

  8. Taenia solium cysticerci synthesize androgens and estrogens in vitro.

    PubMed

    Valdéz, R A; Jiménez, P; Cartas, A L; Gómez, Y; Romano, M C

    2006-04-01

    Cysticerci from Taenia solium develop in the pig muscle and cause severe diseases in humans. Here we report on the capacity of T. solium cysticerci to synthesize sex steroid hormones. T. solium cysticerci were dissected from infected pork meat. Parasites were incubated for different periods in culture media plus antibiotics and tritiated steroid precursors. Blanks and parasite culture media were extracted and analyzed by thin-layer chromatography (TLC) in two different solvent systems. In some experiments, the scoleces were incubated separately. Results showed that T. solium cysticerci transform [(3)H]androstenedione to [(3)H]testosterone in a time-dependent manner. The production was confirmed in two different solvent systems. The incubation with [(3)H]testosterone yielded only small amounts of [(3)H]androstenedione. The recrystallization procedure further demonstrated that the metabolite identified by TLC was testosterone. The isolated scoleces incubated in the presence of [(3)H]androstenedione yielded [(3)H]testosterone and small quantities of [(3)H]17beta-estradiol. The results reported here demonstrate that T. solium cysticerci have the capacity to synthesize steroid hormones.

  9. Intrahepatic synthese of immunoglobulin G in chronic liver disease.

    PubMed

    Kronborg, I J; Knopf, P M

    1980-04-01

    A method has been developed to measure the in vitro production of immunoglobulin (Ig) by liver biopsy specimens. Five to 30 mg of liver tissue was cultured for 24 h in Dulbecco's modified Eagle's medium/10% foetal calf serum (FCS) containing radiolabelled leucine (L-[4,5-3H] leucine). The culture medium was collected, centrifuged and the supernatant dialysed to remove labelled leucine. The residual radioactivity was a measure of newly synthesized 3H-labelled proteins released into the medium. The quantity of IgG was determined by immunoprecipitation with monospecific antisera to IgG heavy chains. The presence of IgG in the supernatant was confirmed by chromatography on protein-A Sepharose column. In 6 biopsies without evidence of active inflammation (4 normal and 2 fatty liver by histological criteria) less than 1% of the protein synthesized was IgG. In contrast in the presence of active inflammation in 4 cases of alcoholic hepatitis the IgG percentage ranged from 2 to 6%. Maximal levels of IgG production were detected in 3 cases of chronic active hepatitis (CAH) and ranged from 5 to 30%. The increased Ig synthesis by the liver in alcoholic hepatitis and CAH is presumed to be an index of the intrahepatic host response and may have important implications for mechanisms of liver damage in these diseases.

  10. Large-diameter graphene nanotubes synthesized using Ni nanowire templates.

    PubMed

    Wang, Rui; Hao, Yufeng; Wang, Ziqian; Gong, Hao; Thong, John T L

    2010-12-08

    We report a method to synthesize tubular graphene structures by chemical vapor deposition (CVD) on Ni nanowire templates, using ethylene as a precursor at growth temperature of around 750 °C. Unlike carbon nanotubes that are synthesized via conventional routes, the number of graphene layers is determined by the growth time and is independent of the tube diameter and tube length, which follow those of the nanowire template. This allows us to realize large-diameter tubes with shells comprising a few or many layers of graphene as desired. Thin graphene layers are observed to be highly crystalline, and of uniform thickness throughout the length of the nanowire. Raman analysis shows the presence of a small level of defects typical of CVD-grown graphene. The metallic core could be removed by chemical etching to result in a collapsed tube. Backgated field-effect transistor measurements were conducted on the collapsed graphene tube. This approach to the realization of tubular graphene offers new opportunities for graphene-based nanodevices.

  11. Anticerebral Ischemia-Reperfusion Injury Activity of Synthesized Puerarin Derivatives

    PubMed Central

    Ji, Yubin; Yan, Xinjia

    2016-01-01

    When cerebral ischemia-reperfusion injury happened in patients, multiple pathological processes occur, such as leukocyte infiltration, platelet, and complement activation, which would result in cognitive dysfunction and inflammation. Puerarin has shown protective effect on injury of neural cell. In order to enhance this protective effect of puerarin, puerarin derivatives with different log⁡P values were designed and synthesized. The original phenolic hydroxyl in the puerarin molecules was substituted in order to change the blood-brain barrier permeability and thus enhance the efficacy for preventing cerebral ischemia/reperfusion injury. And the structure of the newly synthesized molecules was confirmed by 1H NMR spectroscopy and mass spectrometry. The mouse model of cerebral artery ischemia/reperfusion injury was established to test the anticerebral ischemia-reperfusion injury activity of the puerarin derivatives. The assays of the water maze, Y maze, brain cortex Ca2+-Mg2+-ATP enzyme, and iNOS enzyme activity were performed in this mouse model. The results showed that puerarin derivative P1-EA and P2-EA were resulting in an increased lipophilicity that enabled the derivatives to pass more efficiently through the blood-brain barrier, thus, improving the protective effects against cerebral ischemia/reperfusion injury. Therefore, derivatives of puerarin may serve as promising approach to improve neuron function in ischemia-reperfusion brain injury-related disorders. PMID:27807543

  12. Magnetic and Structural Properties of Chemically Synthesized Ni and

    NASA Astrophysics Data System (ADS)

    Bonder, Michael; Leslie-Pelecky, Diandra L.; Zhang, X. Q.; Rieke, R. D.

    1996-03-01

    The reduction of nickel salts using a technique developed by Rieke and co-workers produces highly chemically reactive particles with enhanced magnetic properties due to their nanoscale size. As-synthesized particles are 2-5 nm in diameter and range from superparamagnetic to ferromagnetic, depending on synthesis details. Grain sizes from 5 nm to 1000 nm have been produced by subsequent vacuum annealing. The maximum coercivities and remanence ratios are obtained during the first half-hour to hour of annealing. Coercivities in these systems may be up to ten times the value of bulk nickel, with remanence ratios approaching 0.5. Transmission electron microscopy shows that the nickel grains are square and sometimes embedded in a lithium halide matrix. Under appropriate synthesis and annealing conditions, the as-synthesized particles can be transformed into the metastable Ni_3C phase, which has important implications in catalysis. Comparison with Stoner-Wohlfarth and Holz-Scherrer predictions of the magnetic properties will be made.

  13. Characterization of hematite nanoparticles synthesized via two different pathways

    NASA Astrophysics Data System (ADS)

    Das, Soumya; Hendry, M. Jim

    2014-08-01

    Hematite is one of the most common and thermodynamically stable iron oxides found in both natural and anthropogenic systems. Owing to its ubiquity, stability, moderate specific surface area, and ability to sequester metals and metalloids from aquatic systems, it has been the subject of a large number of adsorption studies published during the past few decades. Although preparation techniques are known to affect the surface morphology of hematite nanoparticles, the effects of aging under environmentally relevant conditions have yet to be tested with respect to surface morphology, surface area, and adsorptive capacity. We prepared hematite via two different pathways and aged it under highly alkaline conditions encountered in many mill tailings settings. Crystal habits and morphologies of the hematite nanoparticles were analyzed via scanning electron microscopy and transmission electron microscopy. X-ray diffraction, Raman spectroscopy, and Brunauer-Emmett-Teller surface area analyses were also conducted on the hematite nanoparticles before and after aging. The hematite synthesized via an Fe(III) salt solution (average particle size 37 nm) was morphologically and structurally different from the hematite synthesized via ferrihydrite aging (average particle size 144 nm). Overall, our data demonstrate that the crystallinity of hematite produced via ferrihydrite transformation is susceptible to morphological alterations/modifications. In contrast, the hematite formed via hydrolysis of an Fe(III) salt solution remains very stable in terms of structure, size, and morphology even under extreme experimental conditions.

  14. Construction of a cyanobacterium synthesizing cyclopropane fatty acids.

    PubMed

    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.

  15. Microwave synthesizer using an on-chip Brillouin oscillator.

    PubMed

    Li, Jiang; Lee, Hansuek; Vahala, Kerry J

    2013-01-01

    Low-phase-noise microwave oscillators are important to a wide range of subjects, including communications, radar and metrology. Photonic-based microwave-wave sources now provide record, close-to-carrier phase-noise performance, and compact sources using microcavities are available commercially. Photonics-based solutions address a challenging scaling problem in electronics, increasing attenuation with frequency. A second scaling challenge, however, is to maintain low phase noise in reduced form factor and even integrated systems. On this second front, there has been remarkable progress in the area of microcavity devices with large storage time (high optical quality factor). Here we report generation of highly coherent microwaves using a chip-based device that derives stability from high optical quality factor. The device has a record low electronic white-phase-noise floor for a microcavity-based oscillator and is used as the optical, voltage-controlled oscillator in the first demonstration of a photonic-based, microwave frequency synthesizer. The synthesizer performance is comparable to mid-range commercial devices.

  16. Evolutionary selection of enzymatically synthesized semiconductors from biomimetic mineralization vesicles.

    PubMed

    Bawazer, Lukmaan A; Izumi, Michi; Kolodin, Dmitriy; Neilson, James R; Schwenzer, Birgit; Morse, Daniel E

    2012-06-26

    The way nature evolves and sculpts materials using proteins inspires new approaches to materials engineering but is still not completely understood. Here, we present a cell-free synthetic biological platform to advance studies of biologically synthesized solid-state materials. This platform is capable of simultaneously exerting many of the hierarchical levels of control found in natural biomineralization, including genetic, chemical, spatial, structural, and morphological control, while supporting the evolutionary selection of new mineralizing proteins and the corresponding genetically encoded materials that they produce. DNA-directed protein expression and enzymatic mineralization occur on polystyrene microbeads in water-in-oil emulsions, yielding synthetic surrogates of biomineralizing cells that are then screened by flow sorting, with light-scattering signals used to sort the resulting mineralized composites differentially. We demonstrate the utility of this platform by evolutionarily selecting newly identified silicateins, biomineralizing enzymes previously identified from the silica skeleton of a marine sponge, for enzyme variants capable of synthesizing silicon dioxide (silica) or titanium dioxide (titania) composites. Mineral composites of intermediate strength are preferentially selected to remain intact for identification during cell sorting, and then to collapse postsorting to expose the encoding genes for enzymatic DNA amplification. Some of the newly selected silicatein variants catalyze the formation of crystalline silicates, whereas the parent silicateins lack this ability. The demonstrated bioengineered route to previously undescribed materials introduces in vitro enzyme selection as a viable strategy for mimicking genetic evolution of materials as it occurs in nature.

  17. A green chemistry approach for synthesizing biocompatible gold nanoparticles

    NASA Astrophysics Data System (ADS)

    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

  18. A green chemistry approach for synthesizing biocompatible gold nanoparticles

    PubMed Central

    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 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

  19. A green chemistry approach for synthesizing biocompatible gold nanoparticles.

    PubMed

    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 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

  20. A PLL Synthesizer with Learning Repeatable Fluctuation of Input Signal

    NASA Astrophysics Data System (ADS)

    Ono, Hiroyuki

    This paper describes a high frequency PLL (Phase Locked Loop) synthesizer with a function of learning then eliminating repeatable fluctuation of timing intervals on series input pulses. Typical spindle encoder generates digital pulses according to the revolution speed. The intervals of each pulse have repeatable fluctuation every revolution by eccentricity or warpage of the encoder scale disk. This method provides a programmable counter for the loop counter of PLL circuit and an interval counter with memory in order to learn the repeatable fluctuation. After the learning process, the PLL generates very pure tone clock signal based on the real flutter components of the spindle revolution speed without influenced by encoder errors. This method has been applied to a hard disk test system in order to generate 3GHz read/write clock.

  1. Optical studies of ion-beam synthesized metal alloy nanoparticles

    NASA Astrophysics Data System (ADS)

    Magudapathy, P.; Srivatsava, S. K.; Gangopadhyay, P.; Amirthapandian, S.; Sairam, T. N.; Panigrahi, B. K.

    2015-06-01

    AuxAg1-x alloy nanoparticles with tunable surface plasmon resonance (SPR) have been synthesized on a silica glass substrate. A small Au foil on an Ag foil is irradiated as target substrates such that ion beam falls on both Ag foil and Au foils. Silica slides are kept at an angle ˜45° with respect to the metallic foils. While irradiating the metallic foils with 100 keV Ar+ ions, sputtered Au and Ag atoms get deposited on the silica-glass. In this configuration the foils have been irradiated by Ar+ ions to various fluences at room temperature and the sputtered species are collected on silica slides. Formation of AuxAg1-x nanoparticles has been confirmed from the optical absorption measurements. With respect to the exposure area of Au and Ag foils to the ion beam, the SPR peak position varies from 450 to 500 nm. Green photoluminescence has been observed from these alloy metal nanoparticles.

  2. Concrete Embedded Dye-Synthesized Photovoltaic Solar Cell

    PubMed Central

    Hosseini, T.; Flores-Vivian, I.; Sobolev, K.; Kouklin, N.

    2013-01-01

    This work presents the concept of a monolithic concrete-integrated dye-synthesized photovoltaic solar cell for optical-to-electrical energy conversion and on-site power generation. The transport measurements carried out in the dark revealed the presence of VOC of ~190 mV and ISC of ~9 μA, induced by the electrochemical conversion of concrete-supplied ionic impurities at the electrodes. The current-voltage measurements performed under illumination at incident optical powers of ~46 mW confirmed the generation of electrical power of ~0.64 μW with almost half generated via battery effect. This work presents a first step towards realizing the additional pathways to low-cost electrical power production in urban environments based on a combined use of organic dyes, nanotitania and concrete technology. PMID:24067664

  3. Syntheses of crosslinked latex nanoparticles using differential microemulsion polymerization

    NASA Astrophysics Data System (ADS)

    Hassmoro, N. F.; Rusop, M.; Abdullah, S.

    2013-06-01

    The differential microemulsion polymerization was used to synthesize latex nanoparticles. In this paper, 1, 3-butylene glycol dimethacrylate (1, 3-BGDMA) was used as a crosslinker respectively 1-5 weight% of monomer total. Butyl acrylate (BA), butyl methacrylate (BMA), and methacrylic acid (MAA) was used as the monomer. The thin film of latex nanoparticles were prepared by using spin coating method and have been dried at 100°C for 5 minutes. The amount of the crosslinker added in the polymerization was optimized and we found that the particle sizes fall in the range of 30-60 nm. The structural morphology of the uncrosslinked latex represented the most homogeneous image compared to the crosslinked latex. The effect of the amount of crosslinker on the particle sizes investigated by the Zeta-sizer Nano series while Atomic Force microscopy (AFM) was used to study the structural properties of latex nanoparticles.

  4. Electroosmotic Pumps with Frits Synthesized from Potassium Silicate.

    PubMed

    Nilsson, Sara; Erlandsson, Per G; Robinson, Nathaniel D

    2015-01-01

    Electroosmotic pumps employing silica frits synthesized from potassium silicate as a stationary phase show strong electroosmotic flow velocity and resistance to pressure-driven flow. We characterize these pumps and measure an electroosmotic mobility of 2.5 × 10(-8) m(2)/V s and hydrodynamic resistance per unit length of 70 × 10(17) Pa s/m(4) with a standard deviation of less than 2% even when varying the amount of water used in the potassium silicate mixture. Furthermore, we demonstrate the simple integration of these pumps into a proof-of-concept PDMS lab-on-a-chip device fabricated from a 3D-printed template.

  5. Fe3O4 nanowire arrays synthesized in AAO templates

    NASA Astrophysics Data System (ADS)

    Xue, D. S.; Zhang, L. Y.; Gui, A. B.; Xu, X. F.

    2005-02-01

    Fe3O4 nanowire arrays with an average diameter of about 120 nm and lengths up to 8 μm were synthesized in anodic aluminum oxide templates through electrodepositing and heat treating a precursor β-FeOOH. The nanowires have a polycrystalline spinel structure with a=8.31 Å and each nanowire is composed of fine particles. Influences of the sintering and the reducing temperatures on the products have been demonstrated by Mössbauer spectra and X-ray diffraction. It was found that high-coercivity nanowires can be obtained when the precursor was sintered at 500 °C in air and then reduced at 325 °C in H2. Hysteresis loops measured at room temperature show a clear perpendicular magnetic anisotropy.

  6. Syntheses of neptunium trichloride and measurements of its melting temperature

    NASA Astrophysics Data System (ADS)

    Hayashi, Hirokazu; Takano, Masahide; Kurata, Masaki; Minato, Kazuo

    2013-09-01

    Neptunium trichloride (NpCl3) of high purity was synthesized by the solid state reaction of neptunium nitride with cadmium chloride. Lattice parameters of hexagonal NpCl3 were determined from the powder X-ray diffraction pattern to be a = 0.7428 ± 0.0001 nm and c = 0.4262 ± 0.0003 nm, which fairly agree with the reported values. The melting temperature of NpCl3 was measured on a sample of about 1 mg, hermetically encapsulated in a gold crucible with a differential thermal analyzer. The value determined was 1070 ± 3 K which is close to the recommended value (1075 ± 30 K) derived from the mean value of the melting temperature of UCl3 and of PuCl3.

  7. Nanostructured superhydrophobic films synthesized by electrodeposition of fluorinated polyindoles.

    PubMed

    Ramos Chagas, Gabriela; Darmanin, Thierry; Guittard, Frédéric

    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 substituent position. The polyindoles exhibited hydrophobic and superhydrophobic properties even with a very low roughness. The best results are obtained with PIndole-6-F 6 for which superhydrophobic and highly oleophobic properties are obtained due to the presence of spherical nanoparticles and low surface energy compounds.

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

    DOEpatents

    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.

  9. Nanostructured superhydrophobic films synthesized by electrodeposition of fluorinated polyindoles

    PubMed Central

    Ramos Chagas, Gabriela; Darmanin, Thierry

    2015-01-01

    Summary 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-F 6 for which superhydrophobic and highly oleophobic properties are obtained due to the presence of spherical nanoparticles and low surface energy compounds. PMID:26665079

  10. Magnesium hydroxide nanoparticles synthesized in water-in-oil microemulsions.

    PubMed

    Wu, Jianming; Yan, Hong; Zhang, Xuehu; Wei, Liqiao; Liu, Xuguang; Xu, Bingshe

    2008-08-01

    Well-dispersed magnesium hydroxide nanoplatelets were synthesized by a simple water-in-oil (w/o) microemulsion process, blowing gaseous ammonia (NH(3)) into microemulsion zones solubilized by magnesium chloride solution (MgCl(2)). Typical quaternary microemulsions of Triton X-100/cyclohexane/n-hexanol/water were used as space-confining microreactors for the nucleation, growth, and crystallization of magnesium hydroxide nanoparticles. The obtained magnesium hydroxide was characterized by field-emission scanning electron microscopy (FESEM), high-resolution transmission election microscopy (HRTEM), X-ray powder diffraction (XRD), laser light scattering, Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis-differential scanning calorimetry (TGA-DSC). The mole ratio of water to surfactant (omega(0)) played an important role in the sizes of micelles and nanoparticles, increasing with the increase of omega(0). The compatibility and dispersibility of nanoparticles obtained from reverse micelles were improved in the organic phase.

  11. Expectations and Limits to Synthesize Nuclei with Z ≥ 120

    NASA Astrophysics Data System (ADS)

    Giardina, G.; Fazio, G.; Mandaglio, G.; Manganaro, M.; Nasirov, A. K.; Romaniuk, M. V.; Saccà, C.

    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.

  12. Bone sialoprotein II synthesized by cultured osteoblasts contains tyrosine sulfate

    SciTech Connect

    Ecarot-Charrier, B.; Bouchard, F.; Delloye, C. )

    1989-11-25

    Isolated mouse osteoblasts that retain their osteogenic activity in culture were incubated with (35S) sulfate. Two radiolabeled proteins, in addition to proteoglycans, were extracted from the calcified matrix of osteoblast cultures. All the sulfate label in both proteins was in the form of tyrosine sulfate as assessed by amino acid analysis and thin layer chromatography following alkaline hydrolysis. The elution behavior on DEAE-Sephacel of the major sulfated protein and the apparent Mr on sodium dodecyl sulfate gels were characteristic of bone sialoprotein II extracted from rat. This protein was shown to cross-react with an antiserum raised against bovine bone sialoprotein II, indicating that bone sialoprotein II synthesized by cultured mouse osteoblasts is a tyrosine-sulfated protein. The minor sulfated protein was tentatively identified as bone sialoprotein I or osteopontin based on its elution properties on DEAE-Sephacel and anomalous behavior on sodium dodecyl sulfate gels similar to those reported for rat bone sialoprotein I.

  13. Magnetic Properties of Bio-Synthesized Magnetite Nanoparticles

    SciTech Connect

    Rawn, Claudia J; Yeary, Lucas W; Moon, Ji Won; Love, Lonnie J; Thompson, James R; Phelps, Tommy Joe

    2005-01-01

    Magnetic nanoparticles, which are unique because of both structural and functional elements, have various novel applications. The popularity and practicality of nanoparticle materials create a need for a synthesis method that produces quality particles in sizable quantities. This paper describes such a method, one that uses bacterial synthesis to create nanoparticles of magnetite. The thermophilic bacterial strain Thermoanaerobacter ethanolicus TOR-39 was incubated under anaerobic conditions at 65 C for two weeks in aqueous solution containing Fe ions from a magnetite precursor (akaganeite). Magnetite particles formed outside of bacterial cells. We verified particle size and morphology by using dynamic light scattering, X-ray diffraction, and transmission electron microscopy. Average crystallite size was 45 nm. We characterized the magnetic properties by using a superconducting quantum interference device magnetometer; a saturation magnetization of 77 emu/g was observed at 5 K. These results are comparable to those for chemically synthesized magnetite nanoparticles.

  14. Process for synthesizing compounds from elemental powders and product

    DOEpatents

    Rabin, B.H.; Wright, R.N.

    1993-12-14

    A process for synthesizing intermetallic compounds from elemental powders is described. The elemental powders are initially combined in a ratio which approximates the stoichiometric composition of the intermetallic compound. The mixed powders are then formed into a compact which is heat treated at a controlled rate of heating such that an exothermic reaction between the elements is initiated. The heat treatment may be performed under controlled conditions ranging from a vacuum (pressureless sintering) to compression (hot pressing) to produce a desired densification of the intermetallic compound. In a preferred form of the invention, elemental powders of Fe and Al are combined to form aluminide compounds of Fe[sub 3] Al and FeAl. 25 figures.

  15. Comparisons of synthesized and individual reinforcement contingencies during functional analysis.

    PubMed

    Fisher, Wayne W; Greer, Brian D; Romani, Patrick W; Zangrillo, Amanda N; Owen, Todd M

    2016-09-01

    Researchers typically modify individual functional analysis (FA) conditions after results are inconclusive (Hanley, Iwata, & McCord, 2003). Hanley, Jin, Vanselow, and Hanratty (2014) introduced a marked departure from this practice, using an interview-informed synthesized contingency analysis (IISCA). In the test condition, they delivered multiple contingencies simultaneously (e.g., attention and escape) after each occurrence of problem behavior; in the control condition, they delivered those same reinforcers noncontingently and continuously. In the current investigation, we compared the results of the IISCA with a more traditional FA in which we evaluated each putative reinforcer individually. Four of 5 participants displayed destructive behavior that was sensitive to the individual contingencies evaluated in the traditional FA. By contrast, none of the participants showed a response pattern consistent with the assumption of the IISCA. We discuss the implications of these findings on the development of accurate and efficient functional analyses.

  16. Syncopation creates the sensation of groove in synthesized music examples

    PubMed Central

    Sioros, George; Miron, Marius; Davies, Matthew; Gouyon, Fabien; Madison, Guy

    2014-01-01

    In order to better understand the musical properties which elicit an increased sensation of wanting to move when listening to music—groove—we investigate the effect of adding syncopation to simple piano melodies, under the hypothesis that syncopation is correlated to groove. Across two experiments we examine listeners' experience of groove to synthesized musical stimuli covering a range of syncopation levels and densities of musical events, according to formal rules implemented by a computer algorithm that shifts musical events from strong to weak metrical positions. Results indicate that moderate levels of syncopation lead to significantly higher groove ratings than melodies without any syncopation or with maximum possible syncopation. A comparison between the various transformations and the way they were rated shows that there is no simple relation between syncopation magnitude and groove. PMID:25278923

  17. Polycationic nanoparticles synthesized using ARGET ATRP for drug delivery.

    PubMed

    Forbes, D C; Creixell, M; Frizzell, H; Peppas, N A

    2013-08-01

    This work provides a systemic comparison for ARGET ATRP and UV-initiated polycationic nanoparticles for drug delivery and a guide to deciding which type of polycationic nanoparticles have the best properties for specific applications. Polycationic nanoparticles were synthesized using a previously developed UV-initiated photoemulsion polymerization or a newly developed ARGET ATRP synthesis technique. The effect of the ratio of hydrophobic monomer in the feed was evaluated. Increasing the feed ratio of hydrophobic monomer was necessary to maintain biocompatibility and pH-responsive membrane disruptive characteristics when switching from the UV-initiated polymerization to ARGET ATRP. The resulting polycationic nanoparticles have utility as drug delivery carriers for hydrophobic drugs and/or nucleic acids. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Horizontal axis wind turbine post stall airfoil characteristics synthesization

    NASA Technical Reports Server (NTRS)

    Tangler, James L.; Ostowari, Cyrus

    1995-01-01

    Blade-element/momentum performance prediction codes are routinely used for wind turbine design and analysis. A weakness of these codes is their inability to consistently predict peak power upon which the machine structural design and cost are strongly dependent. The purpose of this study was to compare post-stall airfoil characteristics synthesization theory to a systematically acquired wind tunnel data set in which the effects of aspect ratio, airfoil thickness, and Reynolds number were investigated. The results of this comparison identified discrepancies between current theory and the wind tunnel data which could not be resolved. Other factors not previously investigated may account for these discrepancies and have a significant effect on peak power prediction.

  19. Enhanced photocatalytic activity of electrochemically synthesized aluminum oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    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.

  20. Synthesizing Existing CSMA and TDMA Based MAC Protocols for VANETs.

    PubMed

    Huang, Jiawei; Li, Qi; Zhong, Shaohua; Liu, Lianhai; Zhong, Ping; Wang, Jianxin; Ye, Jin

    2017-02-10

    Many Carrier Sense Multiple Access (CSMA) and Time Division Multiple Access (TDMA) based medium access control (MAC) protocols for vehicular ad hoc networks (VANETs) have been proposed recently. Contrary to the common perception that they are competitors, we argue that the underlying strategies used in these MAC protocols are complementary. Based on this insight, we design CTMAC, a MAC protocol that synthesizes existing strategies; namely, random accessing channel (used in CSMA-style protocols) and arbitral reserving channel (used in TDMA-based protocols). CTMAC swiftly changes its strategy according to the vehicle density, and its performance is better than the state-of-the-art protocols. We evaluate CTMAC using at-scale simulations. Our results show that CTMAC reduces the channel completion time and increases the network goodput by 45% for a wide range of application workloads and network settings.

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

    PubMed Central

    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

  2. Concrete embedded dye-synthesized photovoltaic solar cell.

    PubMed

    Hosseini, T; Flores-Vivian, I; Sobolev, K; Kouklin, N

    2013-09-25

    This work presents the concept of a monolithic concrete-integrated dye-synthesized photovoltaic solar cell for optical-to-electrical energy conversion and on-site power generation. The transport measurements carried out in the dark revealed the presence of VOC of ~190 mV and ISC of ~9 μA, induced by the electrochemical conversion of concrete-supplied ionic impurities at the electrodes. The current-voltage measurements performed under illumination at incident optical powers of ~46 mW confirmed the generation of electrical power of ~0.64 μW with almost half generated via battery effect. This work presents a first step towards realizing the additional pathways to low-cost electrical power production in urban environments based on a combined use of organic dyes, nanotitania and concrete technology.

  3. Nonicosahedral boron allotrope synthesized at high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Chuvashova, Irina; Bykova, Elena; Bykov, Maxim; Prakapenka, Vitali; Glazyrin, Konstantin; Mezouar, Mohamed; Dubrovinsky, Leonid; Dubrovinskaia, Natalia

    2017-05-01

    Theoretical predictions of pressure-induced phase transformations often become long-standing enigmas because of limitations of contemporary available experimental possibilities. Hitherto the existence of a nonicosahedral boron allotrope has been one of them. Here we report on a nonicosahedral boron allotrope, which we denoted as ζ -B, with the orthorhombic α -Ga-type structure (space group Cmce) synthesized in a diamond-anvil cell at extreme high-pressure high-temperature conditions (115 GPa and 2100 K). The structure of ζ -B was solved using single-crystal synchrotron x-ray diffraction and its compressional behavior was studied in the range of very high pressures (115-135 GPa). Experimental validation of theoretical predictions reveals the degree of our up-to-date comprehension of condensed matter and promotes further development of solid-state physics and chemistry.

  4. Horizontal axis wind turbine post stall airfoil characteristics synthesization

    SciTech Connect

    Tangler, J.L. . Wind Energy Research Center); Ostowari, C. )

    1991-06-01

    Blade-element/momentum performance prediction codes are routinely used for wind turbine design and analysis. A weakness of these codes is their inability to consistently predict peak power upon which the machine structural design and cost are strongly dependent. The purpose of this study was to compare post-stall airfoil characteristics synthesization theory to a systematically acquired wind tunnel data set in which the effects of aspect ratio, airfoil thickness, and Reynolds number were investigated. The results of this comparison identified discrepancies between current theory and the wind tunnel data which could not be resolved. Other factors not previously investigated may account for these discrepancies and have a significant effect on peak power prediction. 5 refs., 3 figs.

  5. Scalable syntheses of the BET bromodomain inhibitor JQ1

    PubMed Central

    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

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

    NASA Astrophysics Data System (ADS)

    Rostro-Kohanloo, Betty C.; Bickford, Lissett R.; Payne, Courtney M.; Day, Emily S.; Anderson, Lindsey J. E.; Zhong, Meng; Lee, Seunghyun; Mayer, Kathryn M.; Zal, Tomasz; Adam, Liana; Dinney, Colin P. N.; Drezek, Rebekah A.; West, Jennifer L.; Hafner, Jason H.

    2009-10-01

    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.

  7. Thermogravimetric study of vapor pressure of TATP synthesized without recrystallization.

    PubMed

    Mbah, Jonathan; Knott, Debra; Steward, Scott

    2014-11-01

    This study aims at characterizing the vapor pressure signatures generated by triacetone triperoxide (TATP) that was synthesized without recrystallization by thermogravimmetric analysis (TGA) for exploitation by standoff detection technologies of explosive devices. The thermal behavior of the nonrecrystallized sample was compared with reported values. Any phase change, melting point and decomposition identification were studied by differential scanning calorimeter. Vapor pressures were estimated by the Langmuir method of evaporation from an open surface in a vacuum. Vapor pressures of TATP at different temperatures were calculated using the linear logarithmic relationship obtained from benzoic acid reference standard. Sublimation of TATP was found to follow apparent zero-order kinetics and sublimes at steady rates at 298 K and above. While the enthalpy of sublimation found, 71.7 kJ mol(-1), is in agreement with reported values the vapor pressures deviated significantly. The differences in the vapor pressures behavior are attributable to the synthesis pathway chosen in this study.

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

    PubMed

    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.

  9. Effect of tactile vibration on annoyance to synthesized propfan noise

    NASA Technical Reports Server (NTRS)

    Clevenson, S. A.

    1981-01-01

    Design information that maximizes passenger comfort for propfan aircraft is presented. Predicted noise and vibration environments and the resultant passenger acceptability were studied. The effect of high frequency tactile vibration (i.e., greater than 30 Hz) on passenger reactions was analyzed. Passenger reactions to a wide range of noise with and without tactile vibration was studied. The passenger ride quality simulator was employed using subjects who evaluated either synthesized propeller noises only, or these noises combined with seat/arm vibration. The noises ranging from 80-100 dB consisted of a turbulent boundary layer noise with a factorial combination of five blade passage frequencies (50-200 Hz), two harmonic rolloffs, and three tone/noise ratios. It is indicated that passenger reaction (annoyance) to noise is not significantly changed in the presence of tactile vibration.

  10. Benzoin Radicals as Reducing Agent for Synthesizing Ultrathin Copper Nanowires.

    PubMed

    Cui, Fan; Dou, Letian; Yang, Qin; Yu, Yi; Niu, Zhiqiang; Sun, Yuchun; Liu, Hao; Dehestani, Ahmad; Schierle-Arndt, Kerstin; Yang, Peidong

    2017-03-01

    In this work, we report a new, general synthetic approach that uses heat driven benzoin radicals to grow ultrathin copper nanowires with tunable diameters. This is the first time carbon organic radicals have been used as a reducing agent in metal nanowire synthesis. In-situ temperature dependent electron paramagnetic resonance (EPR) spectroscopic studies show that the active reducing agent is the free radicals produced by benzoins under elevated temperature. Furthermore, the reducing power of benzoin can be readily tuned by symmetrically decorating functional groups on the two benzene rings. When the aromatic rings are modified with electron donating (withdrawing) groups, the reducing power is promoted (suppressed). The controllable reactivity gives the carbon organic radical great potential as a versatile reducing agent that can be generalized in other metallic nanowire syntheses.

  11. Electrochemical behavior of chemically synthesized selenium thin film.

    PubMed

    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 475 nm. A specific surface area of 30.5 m(2) g(-1) is observed for selenium nanoparticles. The selenium nanoparticles hold mesopores in the range of 1.39 nm, 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 21.98 F g(-1) with 91% electrochemical stability.

  12. Cytotoxicity and antimicrobial activities of green synthesized silver nanoparticles.

    PubMed

    Lokina, S; Stephen, A; Kaviyarasan, V; Arulvasu, C; Narayanan, V

    2014-04-09

    Bio-inspired silver nanoparticles are synthesized using Malus domestica (apple) extract. Polyphenols present in the apple extract act as a reducing and capping agent to produce the silver nanoparticles. UV-Visible analysis shows the surface plasmon resonance (SPR) absorption at 420 nm. The FTIR analysis was used to identify the functional groups responsible for the bio-reduction of silver ion. The XRD and HRTEM images confirm the formation of silver nanoparticles. The minimal inhibitory concentration (MIC) of silver nanoparticles was recorded against most of the bacteria and fungus. Further, MCF-7 human breast adenocarcinoma cancer cell line was employed to observe the efficacy of cancer cell killing. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  13. Guanidines: from classical approaches to efficient catalytic syntheses.

    PubMed

    Alonso-Moreno, Carlos; Antiñolo, Antonio; Carrillo-Hermosilla, Fernando; Otero, Antonio

    2014-05-21

    From organosuperbases capable of base-catalyzing organic reactions, through versatile 'ligand-sets' for use in coordination chemistry, to fundamental entities in medicinal chemistry, guanidines are amongst the most interesting, attractive, valuable, and versatile organic molecules. Since the discovery of these compounds, synthetic chemists have developed new methodologies that are mainly based on multi-step and stoichiometric reactions. Despite the fact that these methodologies are still being used by the interested scientific and industrial communities, drawbacks such as the poor availability of precursors, low yields, and use and production of undesirable substances highlight the need for safe, simple and efficient syntheses of these entities. This review focuses on the metal-mediated catalytic addition of amines to carbodiimides as an atom-economical alternative to the classical synthesis.

  14. Reduction of postsurgical adhesion formation with hydrogels synthesized by radiation

    NASA Astrophysics Data System (ADS)

    Nho, Young-Chang; Lee, Joon-Ho

    2005-07-01

    Biocompatible and biodegradable hydrogels based on carboxymethyl cellulose (CMC) and polyethyleneglycol (PEG) were prepared as physical barriers for preventing surgical adhesions. These interpolymeric hydrogels were synthesized by gamma irradiation crosslinking technique. A 1.5 cm × 1.5 cm of cecal serosa and an adjacent abdominal wall were abraded with bone burr until the serosal surface was disrupted and hemorrhagic but not perforated. The denuded cecum was covered with either CMC/PEG hydrogels or a solution from a CMC/PEG hydrogel. Control rat serosa was not covered. Two weeks later, the rats were sacrificed and the adhesion was scored on a 0-5 scale. Control rat showed a significantly higher incidence of adhesions than either the CMC/PEG hydrogels or a solution from the CMC/PEG hydrogel. In conclusion, these studies demonstrate that CMC/PEG hydrogels have a function of the prevention for an intra abdominal adhesion in a rat model.

  15. Profiling base excision repair glycosylases with synthesized transition state analogs.

    PubMed

    Chu, Aurea M; Fettinger, James C; David, Sheila S

    2011-09-01

    Two base excision repair glycosylase (BER) transition state (TS) mimics, (3R,4R)-1-benzyl (hydroxymethyl) pyrrolidin-3-ol (1NBn) and (3R,4R)-(hydroxymethyl) pyrrolidin-3-ol (1N), were synthesized using an improved method. Several BER glycosylases that repair oxidized DNA bases, bacterial formamidopyrimdine glycosylase (Fpg), human OG glycosylase (hOGG1) and human Nei-like glycosylase 1 (hNEIL1) exhibit exceptionally high affinity (K(d)∼pM) with DNA duplexes containing the 1NBn and 1N nucleotide. Notably, comparison of the K(d) values of both TS mimics relative to an abasic analog (THF) in duplex contexts paired opposite C or A suggest that these DNA repair enzymes use distinctly different mechanisms for damaged base recognition and catalysis despite having overlapping substrate specificities.

  16. Electroosmotic Pumps with Frits Synthesized from Potassium Silicate

    PubMed Central

    Robinson, Nathaniel D.

    2015-01-01

    Electroosmotic pumps employing silica frits synthesized from potassium silicate as a stationary phase show strong electroosmotic flow velocity and resistance to pressure-driven flow. We characterize these pumps and measure an electroosmotic mobility of 2.5×10-8 m2/V s and hydrodynamic resistance per unit length of 70 ×1017 Pa s/m4 with a standard deviation of less than 2% even when varying the amount of water used in the potassium silicate mixture. Furthermore, we demonstrate the simple integration of these pumps into a proof-of-concept PDMS lab-on-a-chip device fabricated from a 3D-printed template. PMID:26629907

  17. Ubiquitination of newly synthesized proteins at the ribosome.

    PubMed

    Wang, Feng; Canadeo, Larissa A; Huibregtse, Jon M

    2015-07-01

    Newly synthesized proteins can be misfolded or damaged because of errors during synthesis or environmental insults (e.g., heat shock), placing a significant burden on protein quality control systems. In addition, numerous human diseases are associated with a deficiency in eliminating aberrant proteins or accumulation of aggregated proteins. Understanding the mechanisms of protein quality control and disposal pathways for misfolded proteins is therefore crucial for therapeutic intervention in these diseases. Quality control processes function at many points in the life cycle of proteins, and a subset act at the actual site of protein synthesis, the ribosome. Here we summarize recent advances in the role of the ubiquitin proteasome system in protein quality control during the process of translation.

  18. Ubiquitination of Newly Synthesized Proteins at the Ribosome

    PubMed Central

    Wang, Feng; Canadeo, Larissa A.; Huibregtse, Jon M.

    2015-01-01

    Newly synthesized proteins can be misfolded or damaged because of errors during synthesis or environmental insults (e.g., heat shock), placing a significant burden on protein quality control systems. In addition, numerous human diseases are associated with a deficiency in eliminating aberrant proteins or accumulation of aggregated proteins. Understanding the mechanisms of protein quality control and disposal pathways for misfolded proteins is therefore crucial for therapeutic intervention in these diseases. Quality control processes function at many points in the life cycle of proteins, and a subset act at the actual site of protein synthesis, the ribosome. Here we summarize recent advances in the role of the ubiquitin proteasome system in protein quality control during the process of translation. PMID:25701549

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

    PubMed

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

    2016-08-24

    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.

  20. Nanosized hydroxyapatite powder synthesized from eggshell and phosphoric acid.

    PubMed

    Lee, Sang-Jin; Yoon, Young-Soo; Lee, Myung-Hyun; Oh, Nam-Sik

    2007-11-01

    The present research describes synthesis of highly sinterable, nano-sized hydroxyapatite (HAp) powders using a wet chemical route with recycled eggshell and phosphoric acid as calcium and phosphorous sources. The raw eggshell was easily turned to CaO by the calcining process, and phosphoric acid was mixed with the calcined eggshell by the wet, ball-milling method. The crystalline development and microstructures of the synthesized powders and sintered samples were examined by X-ray diffractometry and scanning electron microscopy, respectively. The observed phases on the powder synthesis process were dependent on the mixing ratio (wt%) of the calcined eggshell to phosphoric acid and the heating temperature. The ball-milled, nano-sized HAp powder, which has an average particle size of 70 nm, was fully densified at 1300 degrees C for 1h. The Ca/P ratio for stoichiometric composition of HAp was controlled by adjustment of the mixing ratio.

  1. Progress towards realization of a Quantum Matter Synthesizer

    NASA Astrophysics Data System (ADS)

    Downs, Gustaf; Trisnadi, Jonathan; Chin, Cheng

    2016-05-01

    We present our recent progress towards building a new type of optical lattice experiment. Once completed, the Quantum Matter Synthesizer (QMS) will be able to load atoms into a far-detuned lattice projected through a high numerical aperture objective lens, image the atomic distribution and cool the atoms to the vibrational ground state, and then dynamically turn off and rearrange lattice sites to achieve the desired filling fraction and spin order. We will achieve this dynamically re-arrangeable lattice by forming our 2D optical potential with Digital Micromirror Devices (DMD). Here we report the performance of our MOT and initial dRSC, our scheme for transporting atoms from our chamber into our high-resolution imaging glass cell, and our structural design for stabilizing and isolating critical optical components near the glass cell as well as science goals.

  2. Synthesizing Existing CSMA and TDMA Based MAC Protocols for VANETs

    PubMed Central

    Huang, Jiawei; Li, Qi; Zhong, Shaohua; Liu, Lianhai; Zhong, Ping; Wang, Jianxin; Ye, Jin

    2017-01-01

    Many Carrier Sense Multiple Access (CSMA) and Time Division Multiple Access (TDMA) based medium access control (MAC) protocols for vehicular ad hoc networks (VANETs) have been proposed recently. Contrary to the common perception that they are competitors, we argue that the underlying strategies used in these MAC protocols are complementary. Based on this insight, we design CTMAC, a MAC protocol that synthesizes existing strategies; namely, random accessing channel (used in CSMA-style protocols) and arbitral reserving channel (used in TDMA-based protocols). CTMAC swiftly changes its strategy according to the vehicle density, and its performance is better than the state-of-the-art protocols. We evaluate CTMAC using at-scale simulations. Our results show that CTMAC reduces the channel completion time and increases the network goodput by 45% for a wide range of application workloads and network settings. PMID:28208590

  3. Heteroatom-doped graphene materials: syntheses, properties and applications.

    PubMed

    Wang, Xuewan; Sun, Gengzhi; Routh, Parimal; Kim, Dong-Hwan; Huang, Wei; Chen, Peng

    2014-01-01

    Heteroatom doping can endow graphene with various new or improved electromagnetic, physicochemical, optical, and structural properties. This greatly extends the arsenal of graphene materials and their potential for a spectrum of applications. Considering the latest developments, we comprehensively and critically discuss the syntheses, properties and emerging applications of the growing family of heteroatom-doped graphene materials. The advantages, disadvantages, and preferential doping features of current synthesis approaches are compared, aiming to provide clues for developing new and controllable synthetic routes. We emphasize the distinct properties resulting from various dopants, different doping levels and configurations, and synergistic effects from co-dopants, hoping to assist a better understanding of doped graphene materials. The mechanisms underlying their advantageous uses for energy storage, energy conversion, sensing, and gas storage are highlighted, aiming to stimulate more competent applications.

  4. Hydrophilic polymer composites synthesized by electrospinning under dense carbon dioxide

    NASA Astrophysics Data System (ADS)

    Wahyudiono, Okamoto, Koichi; Machmudah, Siti; Kanda, Hideki; Goto, Motonobu

    2015-12-01

    Electrospinning technique is feasible in some applications, it has attracted more attention in recent years. Various polymers have been successfully electrospun into ultrafine fibers in solvent solution and some in melt form. In this work, polyvinylpyrrolidone (PVP) as a hydrophilic polymer would be synthesized by electrospinning under dense carbon dioxide (CO2). The experiments were performed at 40 °C and ˜ 5 MPa. During the electrospinning process, the applied voltage was 10-17 kV and the distance of nozzle and collector was 8 cm. The concentration of PVP solution as a major component was 4 wt%. The results showed that the fibers surface morphology from PVP which blended with poly L-lactide acid (PLLA) were smooth with hollow core fibers at 5 MPa. At the same conditions, PVP-carbon nanotube was also successfully generated into electrospun fiber products with diameter ˜ 2 μm.

  5. Method for synthesizing pollucite from chabazite and cesium chloride

    DOEpatents

    Pereira, Candido

    1999-01-01

    A method for immobilizing waste chlorides salts containing radionuclides and hazardous nuclear material for permanent disposal, and in particular, a method for immobilizing waste chloride salts containing cesium, in a synthetic form of pollucite. The method for synthesizing pollucite from chabazite and cesium chloride includes mixing dry, non-aqueous cesium chloride with chabazite and heating the mixture to a temperature greater than the melting temperature of the cesium chloride, or above about 700.degree. C. The method further comprises significantly improving the rate of retention of cesium in ceramic products comprised of a salt-loaded zeolite by adding about 10% chabazite by weight to the salt-loaded zeolite prior to conversion at elevated temperatures and pressures to the ceramic composite.

  6. Method for synthesizing pollucite from chabazite and cesium chloride

    DOEpatents

    Pereira, C.

    1999-02-23

    A method is described for immobilizing waste chlorides salts containing radionuclides and hazardous nuclear material for permanent disposal, and in particular, a method is described for immobilizing waste chloride salts containing cesium, in a synthetic form of pollucite. The method for synthesizing pollucite from chabazite and cesium chloride includes mixing dry, non-aqueous cesium chloride with chabazite and heating the mixture to a temperature greater than the melting temperature of the cesium chloride, or above about 700 C. The method further comprises significantly improving the rate of retention of cesium in ceramic products comprised of a salt-loaded zeolite by adding about 10% chabazite by weight to the salt-loaded zeolite prior to conversion at elevated temperatures and pressures to the ceramic composite. 3 figs.

  7. Novel route to synthesize CuO nanoplatelets

    SciTech Connect

    Zarate, R.A. Hevia, F.; Fuentes, S.; Fuenzalida, V.M.; Zuniga, A.

    2007-04-15

    A new synthesis route to obtain high-purity cupric oxide, CuO, using the hydrothermal reaction of copper sulfide and a NaOH solution in an oxygen atmosphere has been developed. The synthesized products showed nanoplatelet-like morphologies with rectangular cross-sections and dimensions at the nanometric scale. Variations in the oxygen partial pressure and synthesis temperature produced changes in size and shape, being found that the proliferation of nanoplatelet structures occurred at 200 deg. C and 30 bar. - Graphical abstract: Transmission electron microscopy image of a CuO nanoplatelet. The inset is an electron diffraction pattern of this twined CuO nanoplatelet exhibiting a monoclinic crystal structure.

  8. Using Qualitative Metasummary to Synthesize Qualitative and Quantitative Descriptive Findings

    PubMed Central

    Sandelowski, Margarete; Barroso, Julie; Voils, Corrine I.

    2008-01-01

    The new imperative in the health disciplines to be more methodologically inclusive has generated a growing interest in mixed research synthesis, or the integration of qualitative and quantitative research findings. Qualitative metasummary is a quantitatively oriented aggregation of qualitative findings originally developed to accommodate the distinctive features of qualitative surveys. Yet these findings are similar in form and mode of production to the descriptive findings researchers often present in addition to the results of bivariate and multivariable analyses. Qualitative metasummary, which includes the extraction, grouping, and formatting of findings, and the calculation of frequency and intensity effect sizes, can be used to produce mixed research syntheses and to conduct a posteriori analyses of the relationship between reports and findings. PMID:17243111

  9. High-yielding syntheses of hydrophilic, conjugatable chlorins and bacteriochlorins†

    PubMed Central

    McCarthy, Jason R.; Bhaumik, Jayeeta; Merbouh, Nabyl; Weissleder, Ralph

    2009-01-01

    SUMMARY Next-generation photodynamic therapy agents based upon the conjugation of multiple photosensitizers to a targeting backbone will allow for more efficacious light-based therapies. To this end, we have developed glucose-modified chlorins and bacteriochlorins featuring a reactive carboxylic acid linker for conjugation to targeting moities. The photosensitizers were synthesized in relatively high yields from meso-tetra(p-aminophenyl)porphyrin, and resulted in neutral, hydrophilic chromophores with superb absorption profiles in the far-red and near-infrared portions of the electromagnetic spectrum. In addition, conjugation of these photosensitizers to a model nanoscaffold (crosslinked dextran-coated nanoparticles) demonstrated that the inclusion of hydrophilic sugar moieties increased the number of dyes that can be loaded while maintaining suspension stability. The described compounds are expected to be particularly useful in the synthesis of a number of targeted nanotherapeutic systems. PMID:19675897

  10. Extreme halophiles synthesize betaine from glycine by methylation.

    PubMed

    Nyyssola, A; Kerovuo, J; Kaukinen, P; von Weymarn, N; Reinikainen, T

    2000-07-21

    Glycine betaine is a compatible solute, which is able to restore and maintain osmotic balance of living cells. It is synthesized and accumulated in response to abiotic stress. Betaine acts also as a methyl group donor and has a number of important applications including its use as a feed additive. The known biosynthetic pathways of betaine are universal and very well characterized. A number of enzymes catalyzing the two-step oxidation of choline to betaine have been isolated. In this work we have studied a novel betaine biosynthetic pathway in two phylogenically distant extreme halophiles, Actinopolyspora halophila and Ectothiorhodospira halochloris. We have identified a three-step series of methylation reactions from glycine to betaine, which is catalyzed by two methyltransferases, glycine sarcosine methyltransferase and sarcosine dimethylglycine methyltransferase, with partially overlapping substrate specificity. The methyltransferases from the two organisms show high sequence homology. E. halochloris methyltransferase genes were successfully expressed in Escherichia coli, and betaine accumulation and improved salt tolerance were demonstrated.

  11. Syntheses of C-peptides and human proinsulin.

    PubMed

    Yanaihara, N; Yanaihara, C; Sakagami, M; Sakura, N; Hashimoto, T; Nishida, T

    1978-01-01

    Syntheses of human, dog, rat, and duck C-peptides and their analogues and preliminary results on the total synthesis of human proinsulin are described. In the syntheses of the C-peptides, chain elongation was performed exclusively by the azide-fragment condensation method in solution. The synthetic human, dog, rat, and duck C-peptides and their analogues were proved to be homogeneous by several analytic means. With these synthetic peptides, radioimmunoassay systems for dog, rat, and duck C-peptides were developed. For the total synthesis of human proinsulin, 10 protected peptide hydrazides were prepared, and the linearly protected hexaoctacontapeptide having the proposed sequence of human proinsulin was constructed by the azide-fragment condensation method in solution starting from the C-terminal undecapeptide (HP 75-86). After deblocking of the alpha-amino protection, the partially protected hexaoctacontapeptide was treated with sodium in liquid ammonia. The ensuing sulfhydryl form was converted to the S-sulfonate form, which was reduced and then air-oxidized. The oxidized material was purified by gel filtration on Sephadex G-50 (fine) followed by ion-exchange chromatography on DEAE-cellulose. The cross-reactivity in the insulin radioimmunoassay of the ensuing product was 62.5 per cent of porcine proinsulin on a weight basis at B/Bo = 60 per cent. Acid hydrolysis and amino acid analysis of this product gave the theoretically expected ratios. In addition, this peptide, as well as the S-sulfonate form of the hexaoctacontapeptide, showed displacement curves superimposable on that of synthetic human C-peptide on an equimolar basis in the human C-peptide radioimmunoassay (antiserum 527). These results confirm the synthesis of human proinsulin.

  12. Shock-synthesized hexagonal diamonds in Younger Dryas boundary sediments

    PubMed Central

    Kennett, Douglas J.; Kennett, James P.; West, Allen; West, G. James; Bunch, Ted E.; Culleton, Brendan J.; Erlandson, Jon M.; Que Hee, Shane S.; Johnson, John R.; Mercer, Chris; Shen, Feng; Sellers, Marilee; Stafford, Thomas W.; Stich, Adrienne; Weaver, James C.; Wittke, James H.; Wolbach, Wendy S.

    2009-01-01

    The long-standing controversy regarding the late Pleistocene megafaunal extinctions in North America has been invigorated by a hypothesis implicating a cosmic impact at the Ållerød-Younger Dryas boundary or YDB (≈12,900 ± 100 cal BP or 10,900 ± 100 14C years). Abrupt ecosystem disruption caused by this event may have triggered the megafaunal extinctions, along with reductions in other animal populations, including humans. The hypothesis remains controversial due to absence of shocked minerals, tektites, and impact craters. Here, we report the presence of shock-synthesized hexagonal nanodiamonds (lonsdaleite) in YDB sediments dating to ≈12,950 ± 50 cal BP at Arlington Canyon, Santa Rosa Island, California. Lonsdaleite is known on Earth only in meteorites and impact craters, and its presence strongly supports a cosmic impact event, further strengthened by its co-occurrence with other nanometer-sized diamond polymorphs (n-diamonds and cubics). These shock-synthesized diamonds are also associated with proxies indicating major biomass burning (charcoal, carbon spherules, and soot). This biomass burning at the Younger Dryas (YD) onset is regional in extent, based on evidence from adjacent Santa Barbara Basin and coeval with broader continent-wide biomass burning. Biomass burning also coincides with abrupt sediment mass wasting and ecological disruption and the last known occurrence of pygmy mammoths (Mammuthus exilis) on the Channel Islands, correlating with broader animal extinctions throughout North America. The only previously known co-occurrence of nanodiamonds, soot, and extinction is the Cretaceous-Tertiary (K/T) impact layer. These data are consistent with abrupt ecosystem change and megafaunal extinction possibly triggered by a cosmic impact over North America at ≈12,900 ± 100 cal BP. PMID:19620728

  13. Concanavalin A is synthesized as a glycoprotein precursor.

    PubMed

    Herman, E M; Shannon, L M; Chrispeels, M J

    1985-07-01

    Concanavalin A (Con A) is a tetrameric lectin which is synthesized in the cotyledons of developing jack-bean (Canavalia ensiformis (L.) D.C.) seeds and accumulates in the protein bodies of storage-parenchyma cells. The polypeptides of Con A have a molecular weight of 27000 and a relative molecular mass (Mr) of 30000 when analyzed by gel electrophoresis on denaturing polyacrylamide gels. In-vitro translation of RNA isolated from immature jack-bean cotyledons shows that Con A is synthesized as a polypeptide with Mr 34000. In-vivo pulse labeling of cotyledons with radioactive amino acids or glucosamine also resulted in the formation of a 34000-Mr polypeptide. In-vivo labeling with radioactive amino acids in the presence of tunicamycin yielded an additional polypeptide of 32000 Mr. Together these results indicate that Con A is cotranslationally processed by the removal of a signal sequence and the addition of an oligosaccharide side chain of corresponding size. Analysis of the structure of the oligogosaccharide side chain was accomplished through glycosidase digestion of glycopeptides isolated from [(3)H]glucosamine-labeled Con A. Incubation of the labeled glycopeptides with endoglycosidase H, α-mannosidase or β-N-acetylglucosaminidase, followed by gel filtration, allowed us to deduce that the oligosaccharide side chain of pro-Con A is a high-mannose oligosaccharide. Pulse-chase experiments with labeled amino acids are consistent with the interpretation that the glycosylated precursor of Con A is processed to mature Con A (Mr=30000). The 4000 decrease in Mr is interpreted to result from the removal of a small glycopeptide. The implications of the conversion of a glycoprotein pro-Con A to mature Con A are discussed in the context of the unique circular permutation of the primary structure of Con A.

  14. Androgenic-anabolic activities of some new synthesized steroidal pyrane, pyridine and thiopyrimidine derivatives.

    PubMed

    Abdalla, Mohamed M; Amr, Abd El-Galil E; Al-Omar, Mohamed A; Hussain, Azza A; Amer, Mohamed S

    2014-01-01

    In continuation of our previous work, fused steroidal derivatives with pyrane, pyridine, pyrimidine moieties were synthesized and evaluated as androgenic-anabolic agents. Some of the newly synthesized compounds are exhibited pronounced androgenic-anabolic activities.

  15. ADVANCES IN GREEN CHEMISTRY: CHEMICAL SYNTHESES USING MICROWAVE IRRADIATION, ISBN 81-901238-5-8

    EPA Science Inventory

    16. Abstract Advances in Green Chemistry: Chemical Syntheses Using Microwave Irradiation
    Microwave-accelerated chemical syntheses in solvents as well as under solvent-free conditions have witnessed an explosive growth. The technique has found widespread application predomi...

  16. ADVANCES IN GREEN CHEMISTRY: CHEMICAL SYNTHESES USING MICROWAVE IRRADIATION, ISBN 81-901238-5-8

    EPA Science Inventory

    16. Abstract Advances in Green Chemistry: Chemical Syntheses Using Microwave Irradiation
    Microwave-accelerated chemical syntheses in solvents as well as under solvent-free conditions have witnessed an explosive growth. The technique has found widespread application predomi...

  17. Genome mining of mycosporine-like amino acid (MAA) synthesizing and non-synthesizing cyanobacteria: A bioinformatics study.

    PubMed

    Singh, Shailendra P; Klisch, Manfred; Sinha, Rajeshwar P; Häder, Donat-P

    2010-02-01

    Mycosporine-like amino acids (MAAs) are a family of more than 20 compounds having absorption maxima between 310 and 362 nm. These compounds are well known for their UV-absorbing/screening role in various organisms and seem to have evolutionary significance. In the present investigation we tested four cyanobacteria, e.g., Anabaena variabilis PCC 7937, Anabaena sp. PCC 7120, Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 6301, for their ability to synthesize MAA and conducted genomic and phylogenetic analysis to identify the possible set of genes that might be involved in the biosynthesis of these compounds. Out of the four investigated species, only A. variabilis PCC 7937 was able to synthesize MAA. Genome mining identified a combination of genes, YP_324358 (predicted DHQ synthase) and YP_324357 (O-methyltransferase), which were present only in A. variabilis PCC 7937 and missing in the other studied cyanobacteria. Phylogenetic analysis revealed that these two genes are transferred from a cyanobacterial donor to dinoflagellates and finally to metazoa by a lateral gene transfer event. All other cyanobacteria, which have these two genes, also had another copy of the DHQ synthase gene. The predicted protein structure for YP_324358 also suggested that this product is different from the chemically characterized DHQ synthase of Aspergillus nidulans contrary to the YP_324879, which was predicted to be similar to the DHQ synthase. The present study provides a first insight into the genes of cyanobacteria involved in MAA biosynthesis and thus widens the field of research for molecular, bioinformatics and phylogenetic analysis of these evolutionary and industrially important compounds. Based on the results we propose that YP_324358 and YP_324357 gene products are involved in the biosynthesis of the common core (deoxygadusol) of all MAAs.

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

    NASA Astrophysics Data System (ADS)

    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

  19. Syntheses and Chemosensory of Anthracene and Phenanthrene Bisimide Derivatives

    NASA Technical Reports Server (NTRS)

    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

  20. Syntheses and Chemosensory of Anthracene and Phenanthrene Bisimide Derivatives

    NASA Technical Reports Server (NTRS)

    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. A Feasibility Study of Synthesizing Subsurfaces Modeled with Computational Neural Networks

    NASA Technical Reports Server (NTRS)

    Wang, John T.; Housner, Jerrold M.; Szewczyk, Z. Peter

    1998-01-01

    This paper investigates the feasibility of synthesizing substructures modeled with computational neural networks. Substructures are modeled individually with computational neural networks and the response of the assembled structure is predicted by synthesizing the neural networks. A superposition approach is applied to synthesize models for statically determinate substructures while an interface displacement collocation approach is used to synthesize statically indeterminate substructure models. Beam and plate substructures along with components of a complicated Next Generation Space Telescope (NGST) model are used in this feasibility study. In this paper, the limitations and difficulties of synthesizing substructures modeled with neural networks are also discussed.

  2. Nonlinear spin wave magnetization of solution synthesized Ni nanoparticles

    NASA Astrophysics Data System (ADS)

    Vitta, Satish

    2007-03-01

    The magnetic properties of Ni nanoparticles synthesized using a soft chemical method followed by heat treatment in H2 atmosphere have been studied in detail. The powder consists of pure Ni with no additional phase and the average crystallite size is 30±5nm, determined using the modified Scherer relation. The crystallites tend to agglomerate into large particles of sizes 50-100nm, as observed by transmission electron microscopy. The saturation magnetization is found to be 46.42emug-1 at 5K, about 80% of the bulk magnetization value. The temperature dependence of saturation magnetization for T <0.5TC is found to deviate from the linear Bloch's T3/2 law indicating that spin wave interactions needs to be considered to understand the behavior. The spin wave stiffness constant obtained by fitting the saturation magnetization decay to a nonlinear spin wave model is lower by an order of magnitude compared to that of bulk Ni. The coercivity on the other hand decreases from 67Oe at 5Kto36Oe at 300K with a temperature dependence slower than the T1/2 behavior predicted for noninteracting superparamagnetic particles.

  3. Water linked 3D coordination polymers: Syntheses, structures and applications

    NASA Astrophysics Data System (ADS)

    Singh, Suryabhan; Bhim, Anupam

    2016-12-01

    Three new coordination polymers (CPs) based on Cd and Pb, [Cd(OBA)(μ-H2O)(H2O)]n1, [Pb(OBA)(μ-H2O)]n2 [where OBA=4,4'-Oxybis(benzoate)] and [Pb(SDBA)(H2O)]n.1/4DMF 3 (SDBA=4,4'-Sulfonyldibenzoate), have been synthesized and characterized. The single crystal structural studies reveal that CPs 1 and 2 have three dimensional structure. A water molecule bridges two metal centres which appears to the responsible for the dimensionality increase from 2D to 3D. Compound 3 has a supramolecular 3D structure involving water molecule and hydrogen bonds. A structural transformation is observed when 3 was heated at 100 °C or kept in methanol, forming [Pb(SDBA)]n4. Compound 4 is used as supporting matrix for palladium nanoparticles, PdNPs@4. The PdNPs@4 exhibits good catalytic activity toward the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH4 at room temperature. Luminescence studies revealed that all CPs could be an effective sensor for nitroaromatic explosives.

  4. [Studies on the efficient syntheses of the drug metabolites].

    PubMed

    Otsubo, K

    2000-11-01

    This review summarizes our recent findings in the syntheses of drug metabolites. The metabolites of Grepafloxacin (1) and OPC-14117 (10) were prepared from the common intermediates (5) and (21), respectively. Moreover, treatment of 10 with a model P450 system led to a benzyl alcohol derivative (11) in one step. OPC-31260 (22) was efficiently N-dealkylated using several metalloporphyrins with oxidants to afford three metabolites (23-25). In addition, I succeeded in obtaining the metabolite (23) in high yield from N-oxide (26) not only as an oxygen donor but also as a substrate, there after, in the model P450 system. Optically active metabolites of OPC-29030 (27) were prepared by enzyme-catalyzed enantioselective transesterification of racemic sulfinyl metabolites. On the other hand, a chiral 1,1'-bi-2-naphthol derivative (38a) was found to be an efficient asymmetric acylating agent for a secondary alcohol (36) which is a valuable intermediate for preparing optically active metabolites of 22. Furthermore, metabolites (45) and (47) of OPC-21268 (44) were prepared using SmI2-induced cyclization and oxidative decarboxylation with Pb(OAc)4 as key steps, respectively.

  5. A subjective evaluation of synthesized STOL airplane noises

    NASA Technical Reports Server (NTRS)

    Powell, C. A., Jr.

    1973-01-01

    A magnitude-estimation experiment was conducted to evaluate the subjective annoyance of the noise generated by possible future turbofan STOL aircraft as compared to that of several current CTOL aircraft. In addition, some of the units used to scale the magnitude of aircraft noise were evaluated with respect to their applicability to STOL noise. Twenty test subjects rated their annoyance to a total of 119 noises over a range of 75 PNdb to 105 PNdb. Their subjective ratings were compared with acoustical analysis of the noises in terms of 28 rating scale units. The synthesized STOL noises of this experiment were found to be slightly more annoying than the conventional CTOL noises at equal levels of PNL and EPNL. Over the range of levels investigated the scaling units, with a few exceptions, were capable of predicting the points of equal annoyance for all of the noises with plus or minus 3 dB. The inclusion of duration corrections, in general, improved the predictive capabilities of the various scaling units; however, tone corrections reduced their predictive capabilities.

  6. Two-Volt Josephson Arbitrary Waveform Synthesizer Using Wilkinson Dividers.

    PubMed

    Flowers-Jacobs, Nathan E; Fox, Anna E; Dresselhaus, Paul D; Schwall, Robert E; Benz, Samuel P

    2016-09-01

    The root-mean-square (rms) output voltage of the NIST Josephson arbitrary waveform synthesizer (JAWS) has been doubled from 1 V to a record 2 V by combining two new 1 V chips on a cryocooler. This higher voltage will improve calibrations of ac thermal voltage converters and precision voltage measurements that require state-of-the-art quantum accuracy, stability, and signal-to-noise ratio. We achieved this increase in output voltage by using four on-chip Wilkinson dividers and eight inner-outer dc blocks, which enable biasing of eight Josephson junction (JJ) arrays with high-speed inputs from only four high-speed pulse generator channels. This approach halves the number of pulse generator channels required in future JAWS systems. We also implemented on-chip superconducting interconnects between JJ arrays, which reduces systematic errors and enables a new modular chip package. Finally, we demonstrate a new technique for measuring and visualizing the operating current range that reduces the measurement time by almost two orders of magnitude and reveals the relationship between distortion in the output spectrum and output pulse sequence errors.

  7. IRBAS: An online database to collate, analyze, and synthesize ...

    EPA Pesticide Factsheets

    Key questions dominating contemporary ecological research and management concern interactions between biodiversity, ecosystem processes, and ecosystem services provision in the face of global change. This is particularly salient for freshwater biodiversity and in the context of river drying and flow‐regime change. Rivers that stop flowing and dry, herein intermittent rivers, are globally prevalent and dynamic ecosystems on which the body of research is expanding rapidly, consistent with the era of big data. However, the data encapsulated by this work remain largely fragmented, limiting our ability to answer the key questions beyond a case‐by‐case basis. To this end, the Intermittent River Biodiversity Analysis and Synthesis (IRBAS; http://irbas.cesab.org) project has collated, analyzed, and synthesized data from across the world on the biodiversity and environmental characteristics of intermittent rivers. The IRBAS database integrates and provides free access to these data, contributing to the growing, and global, knowledge base on these ubiquitous and important river systems, for both theoretical and applied advancement. The IRBAS database currently houses over 2000 data samples collected from six countries across three continents, primarily describing aquatic invertebrate taxa inhabiting intermittent rivers during flowing hydrological phases. As such, there is room to expand the biogeographic and taxonomic coverage, for example, through addition of data

  8. Properties of Poly- and Oligopentacenes Synthesized from Modular Building Blocks

    DOE PAGES

    Kumarasamy, Elango; Sanders, Samuel N.; Pun, Andrew B.; ...

    2016-02-09

    Here, we describe a facile route to well-defined, solution-processable pentacene oligomers (2 to 7) and homopolymer using Suzuki–Miyaura cross-coupling reactions. This synthetic strategy leads to regioisomers, regiopure syn- and anti-trimers were also synthesized, revealing minimal changes in solution properties but significant changes in the solid state arising from differing levels of crystallinity. The materials were characterized by steady state absorption spectroscopy and cyclic voltammetry to study their electronic structure. The steady state absorption spectra exhibit a new high-energy transition in the oligomers, which intensifies as a function of oligomer length, thus increasing the range of absorption to include the entiremore » visible spectrum. Density functional theory calculations indicate that the new peak results directly from the oligomerization. Solid state UV–vis suggests that while the monomer is amorphous, bricklayer packing in the higher oligomers significantly alters the solid state absorption relative to solution. The effect of oligomerization on packing was corroborated by GIWAXS analysis, which revealed crystalline domains in the oligomers. These domains, which are most evident in anti-trimer, become more pronounced upon thermal annealing. Photodegradation studies revealed considerable stability enhancement of oligomers toward oxygen and cycloaddition reactions relative to monomer. The synthesis and characterization of the first higher oligomers and homopolymer of pentacene should pave the way to applications in singlet fission, organic field-effect transistors, and organic photovoltaics.« less

  9. Analysis of chemically synthesized oleoylethanolamide by gas-liquid chromatography.

    PubMed

    Thabuis, Clémentine; Tissot-Favre, Delphine; Bezelgues, Jean-Baptiste; Martin, Jean-Charles; Cruz-Hernandez, Cristina; Dionisi, Fabiola; Destaillats, Frédéric

    2008-08-22

    Oleoylethanolamide (OEA) is known to potentially have beneficial biological effects on weight management by controlling food intake and activating lipid catabolism. In biological fluids, OEA and other endogenously biosynthesized fatty acid ethanolamides are usually analyzed by liquid chromatography-mass spectrometry (LC-MS). The present study provides analytical method to routinely assess the quality of OEA prepared for biological studies by gas-liquid chromatography (GLC). The preparation of OEA for biomedical studies can be performed by N-acylation of oleic acid/esters or using oleoyl chloride. In the present study, OEA was prepared by transamidation of triolein. The analysis of the synthesized OEA has been performed by gas-liquid chromatography of its trimethylsilyl ether (TMS) derivatives. Free OEA cannot be analyzed as such because dehydration of the ethanolamide moiety promptly happens in the GLC injection. This thermal degradation reaction gives rise to the formation of an oxazoline derivative. The TMS moiety prevents the reaction, and the structure of the formed derivative was assessed by mass spectrometry. We show here that OEA prepared for biological studies can be routinely analyzed by GLC after TMS derivative preparation.

  10. Physically synthesized Ni-Cu nanoparticles for magnetic hyperthermia

    PubMed Central

    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

  11. Microrheology of single microtubule filaments and synthesized cytoskeletal networks

    NASA Astrophysics Data System (ADS)

    Koch, Matthias; Rohrbach, Alexander

    2015-03-01

    The ability to sense and respond to external mechanical forces is crucial for cells in many processes such as cell growth and division. Common models on mechanotransduction rely on the conversion of mechanical stimuli to chemical signals in the cell periphery and their translocation by diffusion (passive) or molecular motors (active). These processes are rather slow (~ seconds) and it has been argued that the cytoskeleton itself might be able to transport a mechanical signal within microseconds via stress waves. Microtubules are the stiffest component of the cytoskeleton and thus ideal candidates for this purpose. We study the frequency dependent response of single microtubule filaments and small networks thereof in a bottom-up approach using several (N =2-10) time-multiplexed optical tweezers together with back focal plane interferometry. Small synthesized networks with a defined geometry are constructed using trapped Neutravidin beads as anchor points for biotinylated filaments. The network is then probed by a defined oscillation of one anchor (actor). The frequency dependent response of the remaining beads (sensors) is analyzed experimentally and modeled theoretically over a wide frequency range.

  12. Promotion of hair growth by newly synthesized ceramide mimetic compound.

    PubMed

    Park, Bu-Mahn; Bak, Soon-Sun; Shin, Kyung-Oh; Kim, Minhee; Kim, Daehwan; Jung, Sang-Hun; Jeong, Sekyoo; Sung, Young Kwan; Kim, Hyun Jung

    2017-09-09

    Based on the crucial roles of ceramides in skin barrier function, use of ceramides or their structural mimetic compounds, pseudoceramides, as cosmetic ingredients are getting more popular. While currently used pseudoceramides are intended to substitute the structural roles of ceramides in stratum corneum, development of bioactive pseudoceramides has been repeatedly reported. In this study, based on the potential involvement of sphingolipids in hair cycle regulation, we investigated the effects of newly synthesized pseudoceramide, bis-oleamido isopropyl alcohol (BOI), on hair growth using cultured human hair follicles and animal models. BOI treatment promoted hair growth in cultured human hair follicles ex vivo and induced earlier conversion of telogen into anagen. Although we did not find a significant enhancement of growth factor expression and follicular cell proliferation, BOI treatment resulted in an increased sphinganine and sphingosine contents as well as increased ceramides contents in cultured dermal papilla (DP) cells. Taken together, our data strongly suggest that biologically active pseudoceramide promotes hair growth by stimulating do novo synthesis of sphingolipids in DP cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Supported transition metal nanomaterials: Nanocomposites synthesized by ionizing radiation

    NASA Astrophysics Data System (ADS)

    Clifford, D. M.; Castano, C. E.; Rojas, J. V.

    2017-03-01

    Nanostructures decorated with transition metal nanoparticles using ionizing radiation as a synthesis method in aqueous solutions represents a clean alternative to existing physical, chemical and physicochemical methods. Gamma irradiation of aqueous solutions generates free radicals, both oxidizing and reducing species, all distributed homogeneously. The presence of oxidant scavengers in situ during irradiation generates a highly reductive environment favoring the reduction of the metal precursors promoting seed formation and nanoparticle growth. Particle growth is controlled by addition of surfactants, polymers or various substrates, otherwise referred to as supports, which enhance the formation of well dispersed nanoparticles. Furthermore, the combination of nanoparticles with supports can offer desirable synergisms not solely presented by the substrate or nanoparticles. Thus, supported nanoparticles offer a huge diversity of applications. Among the ionizing radiation methods to synthesize nanomaterials and modify their characteristics, gamma irradiation is of growing interest and it has shown tremendous potential in morphological control and distribution of particle size by judiciously varying parameters including absorbed dose, dose rate, concentration of metal precursor, and stabilizing agents. In this work, major advances on the synthesis of supported nanoparticles through gamma irradiation are reviewed as well as the opportunities to develop and exploit new composites using gamma-rays and other accessible ionizing radiation sources such as X-rays.

  14. s-Block amidoboranes: syntheses, structures, reactivity and applications.

    PubMed

    Stennett, Tom E; Harder, Sjoerd

    2016-02-21

    Metal amidoborane compounds of the alkali- and alkaline earth metals have in recent years found applications in diverse disciplines, notably as hydrogen storage materials, as reagents for the reduction of organic functional groups and as catalysts and intermediates in dehydrocoupling reactions. These functions are connected by the organometallic chemistry of the MNR2BH3 group. This review focusses on central aspects of the s-block amidoborane compounds - their syntheses, structures and reactivity. Well-defined amidoborane complexes of group 2 metals are now available by a variety of solution-phase routes, which has allowed a more detailed analysis of this functional group, which was previously largely confined to solid-state materials chemistry. Structures obtained from X-ray crystallography have begun to provide increased understanding of the fundamental steps of key processes, including amine-borane dehydrocoupling and hydrogen release from primary and secondary amidoboranes. We review structural parameters and reactivity to rationalise the effects of the metal, nitrogen substituents and supporting ligands on catalytic performance and dehydrogenative decomposition routes. Mechanistic features of key processes involving amidoborane compounds as starting materials or intermediates are discussed, alongside emerging applications such as the use of group 1 metal amidoboranes in synthesis. Finally, the future prospects of this vibrant branch of main group chemistry are evaluated.

  15. Barium thiolates and selenolates: syntheses and structural principles.

    PubMed

    Ruhlandt-Senge, K; Englich, U

    2000-11-17

    The synthesis and structural characterization of a family of barium thiolates and selenolates is described. The thiolates were synthesized by metallation of thiols, the selenolates by reductive insertion of the metal into the selenium-selenium bond of diorganodiselenides. Both reaction sequences were carried out by using barium metal dissolved in ammonia; this afforded barium thiolates and selenolates in good yield and purity. The structural principles displayed in the target compounds span a wide range of solid-state formulations, including monomeric and dimeric species, and separated ion triples, namely [Ba(thf)4(SMes*)2] (1; Mes* = 2,4,6-tBU3C6H2), [Ba(thf)4(SeMes*)2] (2), [Ba([18]crown-6)(hmpa)2][(SeMes*)2] (3), the dimeric [(Ba(py)3(thf)(SeTrip)2)2] (4; py = pyridine, Trip = 2,4.6-iPr3C6H2), and [Ba([18]crown-6)(SeTrip)2] (5). The full range of association modes is completed by [Ba([18]crown-6)(hmpa)SMes*][SMes*] (6) communicated earlier by this group. In the solid state, this compound displays an intermediate ion coordination mode: one anion is bound to the metal, while the second one is unassociated. Together these compounds provide structural information about all three different association modes for alkaline earth metal derivatives. This collection of structural data allows important conclusions about the influence of solvation and ligation on structural trends.

  16. Syntheses and analytical characterizations of N-alkyl-arylcyclohexylamines.

    PubMed

    Wallach, Jason; Colestock, Tristan; Cicali, Brian; Elliott, Simon P; Kavanagh, Pierce V; Adejare, Adeboye; Dempster, Nicola M; Brandt, Simon D

    2016-08-01

    The rise in new psychoactive substances that are available as 'research chemicals' (RCs) remains a significant forensic and legislative challenge. A number of arylcyclohexylamines have attracted attention as RCs and continue to be encountered, including 3-MeO-PCP, 3-MeO-PCE and 3-MeO-PCPr. These compounds are commonly perceived as ketamine-like dissociative substances and are believed to act predominantly via antagonism of the N-methyl-D-aspartate (NMDA) receptor. To aid in the identification of newly emerging substances of abuse, the current studies were performed. The syntheses of fifteen N-alkyl-arylcyclohexylamines are described. Analytical characterizations were performed via gas chromatography and high performance liquid chromatography coupled to multiple forms of mass spectrometry as well as nuclear magnetic resonance spectroscopy, ultraviolet diode array detection and infrared spectroscopy. The series consisted of the N-alkyl derivatives (N-methyl, N-ethyl, N-propyl) of phenyl-substituted and isomeric 2-, 3- and 4-methoxy phenylcyclohexylamines, as well as the N-alkyl derivatives obtained from 3-methylphenyl and 2-thienyl moieties. In addition to the presentation of a range of previously unreported data, it was also found that positional isomers of aryl methoxyl-substituted arylcyclohexylamines were readily distinguishable under a variety of analytical conditions. Copyright © 2015 John Wiley & Sons, Ltd.

  17. Two Arabidopsis Proteins Synthesize Acetylated Xylan in Vitro

    PubMed Central

    Urbanowicz, Breeanna R.; Peña, Maria J.; Moniz, Heather A.; Moremen, Kelley W.; York, William S.

    2014-01-01

    SUMMARY Xylan is the third most abundant glycopolymer on earth after cellulose and chitin. As a major component of wood, grain and forage, this natural biopolymer has far-reaching impacts on human life. This highly acetylated cell wall polysaccharide is a vital component of the plant cell wall, which functions as a molecular scaffold, providing plants with mechanical strength and flexibility. Mutations that impair synthesis of the xylan backbone give rise to plants that fail to grow normally due to collapsed xylem cells in the vascular system. Phenotypic analysis of these mutants has implicated many proteins in xylan biosynthesis. However, the enzymes directly responsible for elongation and acetylation of the xylan backbone have not been unambiguously identified. Here we provide direct biochemical evidence that two Arabidopsis thaliana proteins, IRREGULAR XYLEM 10-L (IRX10-L) and ESKIMO1/ TRICOME BIREFRINGENCE 29 (ESK1/TBL29), catalyze these respective processes in vitro. By identifying the elusive xylan synthase and establishing ESK1/TBL29 as the archetypal plant polysaccharide O-acetyltransferase, we have resolved two long-standing questions in plant cell wall biochemistry. These findings shed light on integral steps in the molecular pathways utilized by plants to synthesize a major component of the world's biomass and expand our toolkit for producing glycopolymers with valuable properties. PMID:25141999

  18. Digitally synthesized beat frequency-multiplexed fluorescence lifetime spectroscopy

    PubMed Central

    Chan, Jacky C. K.; Diebold, Eric D.; Buckley, Brandon W.; Mao, Sien; Akbari, Najva; Jalali, Bahram

    2014-01-01

    Frequency domain fluorescence lifetime imaging is a powerful technique that enables the observation of subtle changes in the molecular environment of a fluorescent probe. This technique works by measuring the phase delay between the optical emission and excitation of fluorophores as a function of modulation frequency. However, high-resolution measurements are time consuming, as the excitation modulation frequency must be swept, and faster low-resolution measurements at a single frequency are prone to large errors. Here, we present a low cost optical system for applications in real-time confocal lifetime imaging, which measures the phase vs. frequency spectrum without sweeping. Deemed Lifetime Imaging using Frequency-multiplexed Excitation (LIFE), this technique uses a digitally-synthesized radio frequency comb to drive an acousto-optic deflector, operated in a cat’s-eye configuration, to produce a single laser excitation beam modulated at multiple beat frequencies. We demonstrate simultaneous fluorescence lifetime measurements at 10 frequencies over a bandwidth of 48 MHz, enabling high speed frequency domain lifetime analysis of single- and multi-component sample mixtures. PMID:25574449

  19. A Numerical Method for Synthesizing Atmospheric Temperature and Humidity Profiles.

    NASA Astrophysics Data System (ADS)

    Tatarskaia, Maia S.; Lataitis, Richard J.; Boba Stankov, B.; Tatarskii, Viatcheslav V.

    1998-07-01

    A numerical technique is described for synthesizing realistic atmospheric temperature and humidity profiles. The method uses an ensemble of radiosonde measurements collected at a site of interest. Erroneous profiles are removed by comparing their likelihood with prevailing meteorological conditions. The remaining profiles are decomposed using the method of empirical orthogonal functions. The corresponding eigenprofiles and the statistics of the expansion coefficients are used to numerically generate synthetic profiles that obey the same statistics (i.e., have the same mean, variability, and vertical correlation) as the initial dataset. The technique was applied to a set of approximately 1000 temperature and humidity soundings made in Denver, Colorado, during the winter months of 1991-95. This dataset was divided into four cloud classification categories and daytime and nighttime launches to better characterize typical profiles for the eight cases considered. It was found that 97% of the variance in the soundings could be accounted for by using only five eigenprofiles in the reconstructions. Ensembles of numerically generated profiles can be used to test the accuracy of various retrieval algorithms under controlled conditions not usually available in practice.

  20. Tribological properties of boron nitride synthesized by ion beam deposition

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.; Spalvins, T.

    1985-01-01

    The adhesion and friction behavior of boron nitride films on 440 C bearing stainless steel substrates was examined. The thin films containing the boron nitride were synthesized using an ion beam extracted from a borazine plasma. Sliding friction experiments were conducted with BN in sliding contact with itself and various transition metals. It is indicated that the surfaces of atomically cleaned BN coating film contain a small amount of oxides and carbides, in addition to boron nitride. The coefficients of friction for the BN in contact with metals are related to the relative chemical activity of the metals. The more active the metal, the higher is the coefficient of friction. The adsorption of oxygen on clean metal and BN increases the shear strength of the metal - BN contact and increases the friction. The friction for BN-BN contact is a function of the shear strength of the elastic contacts. Clean BN surfaces exhibit relatively strong interfacial adhesion and high friction. The presence of adsorbates such as adventitious carbon contaminants on the BN surfaces reduces the shear strength of the contact area. In contrast, chemically adsorbed oxygen enhances the shear strength of the BN-BN contact and increases the friction.

  1. Characterization and Biocompatibility of ``Green'' Synthesized Silver Nanoparticles

    NASA Astrophysics Data System (ADS)

    Moulton, Michael; Kunzelman, Samantha; Braydich-Stolle, Laura; Nadagouda, M.; Varma, R.; Hussain, Saber

    2008-10-01

    With ever increasing emphasis on nanotechnology, silver nanoparticle are being considered for many antimicrobial needs ranging from catheter coatings, to burn wound bandages. Current synthesis methods for creating silver nanoparticles typically call for potentially hazardous chemicals, extreme heat, and produce environmentally dangerous byproducts. As a culture intent on reducing our carbon footprint on the earth, societies' focus has turned to ``green'' production capabilities. Therefore, if nanotechnology is to continue to grow at its current rate it is essential that novel ``green'' synthesis of nanoparticles becomes a reality. Furthermore, with the current and near-future applications of silver nanoparticles in biological systems it is imperative to fully analyze the potential toxic effects of these nanoparticles. In this study we have shown that by reducing silver nitrate in solutions of tea extract or epinephrine of varying concentrations spherical silver nanoparticle are formed. Furthermore, evaluation of mitochondrial function (MTS) and membrane integrity (LDH) in alveolar rat macrophages and human keratinocytes showed that these ``green'' synthesized silver nanoparticles were nontoxic.

  2. Two-Volt Josephson Arbitrary Waveform Synthesizer Using Wilkinson Dividers

    PubMed Central

    Flowers-Jacobs, Nathan E.; Fox, Anna E.; Dresselhaus, Paul D.; Schwall, Robert E.; Benz, Samuel P.

    2016-01-01

    The root-mean-square (rms) output voltage of the NIST Josephson arbitrary waveform synthesizer (JAWS) has been doubled from 1 V to a record 2 V by combining two new 1 V chips on a cryocooler. This higher voltage will improve calibrations of ac thermal voltage converters and precision voltage measurements that require state-of-the-art quantum accuracy, stability, and signal-to-noise ratio. We achieved this increase in output voltage by using four on-chip Wilkinson dividers and eight inner-outer dc blocks, which enable biasing of eight Josephson junction (JJ) arrays with high-speed inputs from only four high-speed pulse generator channels. This approach halves the number of pulse generator channels required in future JAWS systems. We also implemented on-chip superconducting interconnects between JJ arrays, which reduces systematic errors and enables a new modular chip package. Finally, we demonstrate a new technique for measuring and visualizing the operating current range that reduces the measurement time by almost two orders of magnitude and reveals the relationship between distortion in the output spectrum and output pulse sequence errors. PMID:27453676

  3. Catecholamine-synthesizing enzymes in adrenals of seasonally acclimatized voles.

    PubMed

    Feist, D D; Feist, C F

    1978-01-01

    Tyrosine hydroxylase (TH) and phenylethanolamine-N-methyltransferase (PNMT) activities were assayed in adrenal glands of the following groups of the Alaskan red-backed vole (Clethrionomys rutilus dawsoni): 1) laboratory reared at 20 degrees C and 2) exposed to 5 degrees C for 1, 3, 7, and 28 days; 3) wild, summer acclimatized; 4) wild, fall acclimatized; and 5) wild, winter acclimatized. TH activity in laboratory-acclimated voles exposed to 5 degrees C was increased by 2 times after 3 days and remained elevated after 28 days. PNMT activity in these same voles was increased after 7 days and also remained elevated after 28 days of cold exposure. In wild-acclimatized voles TH activity and PNMT activity in summer were equivalent to levels in 28-day cold-acclimated laboratory voles. In fall, TH activity was increased to 2.5 times the summer value. It decreased by midwinter, but remained elevated above the summer level. In contrast, PNMT activity appeared unchanged from summer through fall and winter. Pregnant summer voles had markedly increased TH activity. Adrenal norepinephrine and epinephrine did not change significantly with cold acclimation or seasonal acclimatization. Thus, acclimatization of wild voles to fall and winter conditions involved aquisition of a greater capacity to synthesize adrenal catecholamines than that produced by exposing laboratory-reared voles to an extended period of cold.

  4. Kombucha-synthesized bacterial cellulose: preparation, characterization, and biocompatibility evaluation.

    PubMed

    Zhu, Changlai; Li, Feng; Zhou, Xinyang; Lin, Lin; Zhang, Tianyi

    2014-05-01

    Bacterial cellulose (BC) is a natural biomaterial with unique properties suitable for tissue engineering applications, but it has not yet been used for preparing nerve conduits to repair peripheral nerve injuries. The objectives of this study were to prepare and characterize the Kampuchea-synthesized bacterial cellulose (KBC) and further evaluate the biocompatibility of KBC with peripheral nerve cells and tissues in vitro and in vivo. KBC membranes were composed of interwoven ribbons of about 20-100 nm in width, and had a high purity and the same crystallinity as that of cellulose Iα. The results from light and scanning electron microscopy, MTT assay, flow cytometry, and RT-PCR indicated that no significant differences in the morphology and cell function were observed between Schwann cells (SCs) cultured on KBC membranes and glass slips. We also fabricated a nerve conduit using KBC, which was implanted into the spatium intermusculare of rats. At 1, 3, and 6 weeks post-implantation, clinical chemistry and histochemistry showed that there were no significant differences in blood counts, serum biochemical parameters, and tissue reactions between implanted rats and sham-operated rats. Collectively, our data indicated that KBC possessed good biocompatibility with primary cultured SCs and KBC did not exert hematological and histological toxic effects on nerve tissues in vivo. Copyright © 2013 Wiley Periodicals, Inc.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Liquid-phase syntheses of cobalt ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Sinkó, Katalin; Manek, Enikő; Meiszterics, Anikó; Havancsák, Károly; Vainio, Ulla; Peterlik, Herwig

    2012-06-01

    The aim of the present study was to synthesize cobalt-ferrite (CoFe2O4) nanoparticles using various liquid phase methods; sol-gel route, co-precipitation process, and microemulsion technique. The effects of experimental parameters on the particle size, size distribution, morphology, and chemical composition have been studied. The anions of precursors (chloride and nitrate), the solvents (water, n-propanol, ethanol, and benzyl alcohol), the precipitating agent (ammonia, sodium carbonate, and oxalic acid), the surfactants (polydimethylsiloxane, ethyl acetate, citric acid, cethyltrimethylammonium bromide, and sodium dodecil sulfate), their concentrations, and heat treatments were varied in the experiments. The smallest particles (around 40 nm) with narrow polydispersity and spherical shape could be achieved by a simple, fast sol-gel technique in the medium of propanol and ethyl acetate. The size characterization methods have also been investigated. Small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and scanning electron microscopy (SEM) provide the comparison of methods. The SAXS data correspond with the sizes detected by SEM and differ from DLS data. The crystalline phases, morphology, and chemical composition of the particles with different shapes have been analyzed by X-ray diffraction, SEM, and energy dispersive X-ray spectrometer.

  7. Optical studies of ion-beam synthesized metal alloy nanoparticles

    SciTech Connect

    Magudapathy, P. Srivatsava, S. K.; Gangopadhyay, P.; Amirthapandian, S.; Sairam, T. N.; Panigrahi, B. K.

    2015-06-24

    Au{sub x}Ag{sub 1-x} alloy nanoparticles with tunable surface plasmon resonance (SPR) have been synthesized on a silica glass substrate. A small Au foil on an Ag foil is irradiated as target substrates such that ion beam falls on both Ag foil and Au foils. Silica slides are kept at an angle ∼45° with respect to the metallic foils. While irradiating the metallic foils with 100 keV Ar{sup +} ions, sputtered Au and Ag atoms get deposited on the silica-glass. In this configuration the foils have been irradiated by Ar{sup +} ions to various fluences at room temperature and the sputtered species are collected on silica slides. Formation of Au{sub x}Ag{sub 1-x} nanoparticles has been confirmed from the optical absorption measurements. With respect to the exposure area of Au and Ag foils to the ion beam, the SPR peak position varies from 450 to 500 nm. Green photoluminescence has been observed from these alloy metal nanoparticles.

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

    SciTech Connect

    Chen, Shutang; Lee, Soonil

    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.

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

    PubMed Central

    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

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

    NASA Astrophysics Data System (ADS)

    Flores-Castañeda, Mariela; Vega-Jiménez, Alejandro L.; Almaguer-Flores, Argelia; Camps, Enrique; Pérez, Mario; Silva-Bermudez, Phaedra; Berea, Edgardo; Rodil, Sandra E.

    2015-11-01

    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.

  11. Evidence of superdense aluminium synthesized by ultrafast microexplosion

    PubMed Central

    Vailionis, Arturas; Gamaly, Eugene G.; Mizeikis, Vygantas; Yang, Wenge; Rode, Andrei V.; Juodkazis, Saulius

    2011-01-01

    At extreme pressures and temperatures, such as those inside planets and stars, common materials form new dense phases with compacted atomic arrangements and unusual physical properties. The synthesis and study of new phases of matter at pressures above 100 GPa and temperatures above 104 K—warm dense matter—may reveal the functional details of planet and star interiors, and may lead to materials with extraordinary properties. Many phases have been predicted theoretically that may be realized once appropriate formation conditions are found. Here we report the synthesis of a superdense stable phase of body-centred-cubic aluminium, predicted by first-principles theories to exist at pressures above 380 GPa. The superdense Al phase was synthesized in the non-equilibrium conditions of an ultrafast laser-induced microexplosion confined inside sapphire (α-Al2O3). Confined microexplosions offer a strategy to create and recover high-density polymorphs, and a simple method for tabletop study of warm dense matter. PMID:21863012

  12. Evidence of superdense aluminium synthesized by ultrafast microexplosion.

    PubMed

    Vailionis, Arturas; Gamaly, Eugene G; Mizeikis, Vygantas; Yang, Wenge; Rode, Andrei V; Juodkazis, Saulius

    2011-08-23

    At extreme pressures and temperatures, such as those inside planets and stars, common materials form new dense phases with compacted atomic arrangements and unusual physical properties. The synthesis and study of new phases of matter at pressures above 100 GPa and temperatures above 10(4) K--warm dense matter--may reveal the functional details of planet and star interiors, and may lead to materials with extraordinary properties. Many phases have been predicted theoretically that may be realized once appropriate formation conditions are found. Here we report the synthesis of a superdense stable phase of body-centred-cubic aluminium, predicted by first-principles theories to exist at pressures above 380 GPa. The superdense Al phase was synthesized in the non-equilibrium conditions of an ultrafast laser-induced microexplosion confined inside sapphire (α-Al(2)O(3)). Confined microexplosions offer a strategy to create and recover high-density polymorphs, and a simple method for tabletop study of warm dense matter.

  13. Enhanced osteogenic differentiation of stem cells via microfluidics synthesized nanoparticles.

    PubMed

    Hasani-Sadrabadi, Mohammad Mahdi; Hajrezaei, Sana Pour; Emami, Shahriar Hojjati; Bahlakeh, Ghasem; Daneshmandi, Leila; Dashtimoghadam, Erfan; Seyedjafari, Ehsan; Jacob, Karl I; Tayebi, Lobat

    2015-10-01

    Advancement of bone tissue engineering as an alternative for bone regeneration has attracted significant interest due to its potential in reducing the costs and surgical trauma affiliated with the effective treatment of bone defects. We have improved the conventional approach of producing polymeric nanoparticles, as one of the most promising choices for drug delivery systems, using a microfluidics platform, thus further improving our control over osteogenic differentiation of mesenchymal stem cells. Molecular dynamics simulations were carried out for theoretical understanding of our experiments in order to get a more detailed molecular-scale insight into the drug-carrier interactions. In this work, with the sustained intracellular delivery of dexamethasone from microfluidics-synthesized nanoparticles, we explored the effects of particle design on controlling stem cell fates. We believe that the insights learned from this work will lead to the discovery of new strategies to tune differentiation for in situ differentiation or stem cell therapeutics. The use of mesenchymal stem cells has been described by many researchers as a novel therapy for bone regeneration. One major hurdle in this approach is the control of osteogenic differentiation. In this article, the authors described elegantly their microfluidic system in which dexamethasone loaded nanoparticles were produced. This system would allow precise fabrication of nanoparticles and consequently higher efficiency in cellular differentiation. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Plasma-mediated release of morphine from synthesized prodrugs.

    PubMed

    Thomas, Thommey P; Huang, Baohua; Desai, Ankur; Zong, Hong; Cheng, Xue-Min; Kotlyar, Alina; Leroueil, Pascale R; Dunham, Thomas; van der Spek, Abraham; Ward, Brent B; Baker, James R

    2010-11-01

    Two morphine prodrugs ('PDA' and 'PDB') were synthesized and the kinetics of esterase-mediated morphine release from these prodrugs were determined when incubated with plasma from different animal species. Morphine was rapidly released from PDA by all species plasma with the maximum reached within 5-10min; the released morphine was biologically active as determined by an in vitro cAMP assay. The morphine was released from PDB at a slower and species-dependent rate (mouse>rat>guinea pig>human). Morphine's release from PDB appeared to be mediated by carboxyl esterases as the release was inhibited by the carboxyl esterase inhibitor benzil. PDA nor PDB induce cytotoxicity in the neuronal cell lines SK-NSH and SH-SY5Y. The carboxyl and amino functional moieties present on the linker portions of PDA and PDB, respectively, may facilitate their conjugation to nanoparticles to tailor morphine pharmacokinetics and specific targeting. These studies suggest the potential clinical utility of these prodrugs for morphine release at desired rates by administration of their mixture at selected ratios.

  15. Radio-synthesized polyacrylamide hydrogels for proteins release

    NASA Astrophysics Data System (ADS)

    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.

  16. Bacillus subtilis antibiotics: structures, syntheses and specific functions.

    PubMed

    Stein, Torsten

    2005-05-01

    The endospore-forming rhizobacterium Bacillus subtilis- the model system for Gram-positive organisms, is able to produce more than two dozen antibiotics with an amazing variety of structures. The produced anti-microbial active compounds include predominantly peptides that are either ribosomally synthesized and post-translationally modified (lantibiotics and lantibiotic-like peptides) or non-ribosomally generated, as well as a couple of non-peptidic compounds such as polyketides, an aminosugar, and a phospholipid. Here I summarize the structures of all known B. subtilis antibiotics, their biochemistry and genetic analysis of their biosyntheses. An updated summary of well-studied antibiotic regulation pathways is given. Furthermore, current findings are resumed that show roles for distinct B. subtilis antibiotics beyond the "pure" anti-microbial action: Non-ribosomally produced lipopeptides are involved in biofilm and swarming development, lantibiotics function as pheromones in quorum-sensing, and a "killing factor" effectuates programmed cell death in sister cells. A discussion of how these antibiotics may contribute to the survival of B. subtilis in its natural environment is given.

  17. Oriented attachment explains cobalt ferrite nanoparticle growth in bioinspired syntheses.

    PubMed

    Wolff, Annalena; Hetaba, Walid; Wißbrock, Marco; Löffler, Stefan; Mill, Nadine; Eckstädt, Katrin; Dreyer, Axel; Ennen, Inga; Sewald, Norbert; Schattschneider, Peter; Hütten, Andreas

    2014-01-01

    Oriented attachment has created a great debate about the description of crystal growth throughout the last decade. This aggregation-based model has successfully described biomineralization processes as well as forms of inorganic crystal growth, which could not be explained by classical crystal growth theory. Understanding the nanoparticle growth is essential since physical properties, such as the magnetic behavior, are highly dependent on the microstructure, morphology and composition of the inorganic crystals. In this work, the underlying nanoparticle growth of cobalt ferrite nanoparticles in a bioinspired synthesis was studied. Bioinspired syntheses have sparked great interest in recent years due to their ability to influence and alter inorganic crystal growth and therefore tailor properties of nanoparticles. In this synthesis, a short synthetic version of the protein MMS6, involved in nanoparticle formation within magnetotactic bacteria, was used to alter the growth of cobalt ferrite. We demonstrate that the bioinspired nanoparticle growth can be described by the oriented attachment model. The intermediate stages proposed in the theoretical model, including primary-building-block-like substructures as well as mesocrystal-like structures, were observed in HRTEM measurements. These structures display regions of substantial orientation and possess the same shape and size as the resulting discs. An increase in orientation with time was observed in electron diffraction measurements. The change of particle diameter with time agrees with the recently proposed kinetic model for oriented attachment.

  18. Oriented attachment explains cobalt ferrite nanoparticle growth in bioinspired syntheses

    PubMed Central

    Hetaba, Walid; Wißbrock, Marco; Löffler, Stefan; Mill, Nadine; Eckstädt, Katrin; Dreyer, Axel; Ennen, Inga; Sewald, Norbert; Schattschneider, Peter; Hütten, Andreas

    2014-01-01

    Summary Oriented attachment has created a great debate about the description of crystal growth throughout the last decade. This aggregation-based model has successfully described biomineralization processes as well as forms of inorganic crystal growth, which could not be explained by classical crystal growth theory. Understanding the nanoparticle growth is essential since physical properties, such as the magnetic behavior, are highly dependent on the microstructure, morphology and composition of the inorganic crystals. In this work, the underlying nanoparticle growth of cobalt ferrite nanoparticles in a bioinspired synthesis was studied. Bioinspired syntheses have sparked great interest in recent years due to their ability to influence and alter inorganic crystal growth and therefore tailor properties of nanoparticles. In this synthesis, a short synthetic version of the protein MMS6, involved in nanoparticle formation within magnetotactic bacteria, was used to alter the growth of cobalt ferrite. We demonstrate that the bioinspired nanoparticle growth can be described by the oriented attachment model. The intermediate stages proposed in the theoretical model, including primary-building-block-like substructures as well as mesocrystal-like structures, were observed in HRTEM measurements. These structures display regions of substantial orientation and possess the same shape and size as the resulting discs. An increase in orientation with time was observed in electron diffraction measurements. The change of particle diameter with time agrees with the recently proposed kinetic model for oriented attachment. PMID:24605288

  19. Structure and solution properties of enzymatically synthesized glycogen.

    PubMed

    Kajiura, Hideki; Takata, Hiroki; Kuriki, Takashi; Kitamura, Shinichi

    2010-04-19

    Recently, a new enzymatic process for glycogen production was developed. In this process, short-chain amylose is used as a substrate for branching enzymes (BE, EC 2.4.1.18). The molecular weight of the enzymatically synthesized glycogen (ESG) depends on the size and concentration of the substrate. Structural and physicochemical properties of ESG were compared to those of natural source glycogen (NSG). The average chain length, interior chain length, and exterior chain length of ESG were 8.2-11.6, 2.0-3.3, and 4.2-7.6, respectively. These values were within the range of variation of NSG. The appearances of both ESG and NSG in solution were opalescent (milky white and slightly bluish). Furthermore, transmission electron microscopy and atomic force microscopy showed that ESG molecules formed spherical particles, and that there were no differences between ESG and NSG. Viscometric analyses also showed the spherical nature of both glycogens. When ESG and NSG were treated with pullulanase, a glucan-hydrolyzing enzyme known to degrade glycogen only on its surface portion, both glycogens were similarly degraded. These analyses revealed that ESG shares similar molecular shapes and surface properties with NSG.

  20. Efficient syntheses of 17-β-amino steroids.

    PubMed

    Taylor, Scott D; Harris, Jesse

    2011-01-01

    17β-Amino steroids such as 17β-amino-1,3,5(10)-estratrien-3-ol (1), 17β-amino-5α-androstan-3β-ol (2) and, 17β-amino-3β-hydroxyandrost-5-ene (3) have been widely used as a key intermediates in the synthesis of a variety of biologically active steroid derivatives though concise, high yielding syntheses of these compounds has yet to be reported. 17β-Amino-1,3,5(10)-estratrien-3-ol (1) and 17β-amino-5α-androstan-3β-ol (2) were prepared in high yield by reductive amination of estrone and epiandrosterone using benzylamine and sodium triacetoxyborohydride followed by catalytic hydrogenolysis of the resulting 17β-benzylamino derivatives. Attempts to prepare 17β-amino-3β-hydroxyandrost-5-ene (3) from dehydroepiandosterone using a similar approach resulted in partial reduction of the double bond. 17β-Amino-3β-hydroxyandrost-5-ene (3) was ultimately obtained in high yield by reductive amination of dehydroepiandosterone using allylamine and sodium triacetoxyborohydride followed by removal of the allyl group from the resulting 17β-allylamino derivative with dimethylbarbituric acid and Pd(PPh(3))(4) as catalyst.