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Sample records for alkoxides synthesis structure

  1. Synthesis, structure determination, and sol-gel processing of heterometallic heteroleptic alkoxide complexes of late transition metals

    OpenAIRE

    Werndrup, Pia

    2005-01-01

    The thesis describes synthesis of single-source precursors (SSP) for sol-gel preparation of thin films and nanocomposites. The structures of the SSPs were determined by single-crystal X-ray studies and a new group of heterometallic heteroleptic alkoxide complexes have been described, the MII2MV2(acac)2(OR)12 complex, MII= Co, Ni, Zn or Mg, and MV= Ta or Nb, R= Et or Me. Changing to molybdenum oxomethoxide, MoO(OMe)4, instead of tantalum or niobium alkoxide, in the reaction with cobalt acetyla...

  2. Electrochemical synthesis and characterization of tantalum alkoxides

    Institute of Scientific and Technical Information of China (English)

    YANG Sheng-hai; CAI Ya-nan; YANG Hai-ping; JIN Sheng-ming

    2009-01-01

    Tantalum(Ⅴ) propoxide (Ta(Opr~n)_5),isopropoxide (Ta(Opr~I)_5) and butoxide(Ta(Obu~n)_5) were synthesized by electro- chemical reactions of corresponding alcohol at sacrificial tantalum anode in the presence of tetraethylammonium chloride as a conductive additive.The pure products were isolated by reduced pressure distillation under 5 kPa.The crystal of Ta(Opr~l)_5 was obtained by recrystallization from hexane at -10 ℃.These samples were characterized by Fourier transform infrared spectra (FT-IR),Raman spectra,nuclear magnetic resonance spectra (NMR),TG/DTA and ICP-MS.The results show that direct electrochemical synthesis of metal alkoxides has a high current efficiency and electrolysis yield.These alkoxides have a high purity of 99.97% and can be directly used as the precursor of Ta_2O_5 films.

  3. Direct synthesis of some significant metal alkoxides

    International Nuclear Information System (INIS)

    Investigations were carried out with an attempt to study direct synthesis of metal alkoxides from elemental metals and appropriate alcohols. These were done by reacting representative metals of group I, II, III 7 IV (which are Na, Mg, Al and Sn respectively) directly with dry ethanol and dry isopropanol. The products were then analysed by infrared spectrophotometer to meter to identify metal alkoxides formed. Ethanol was found to have more acidic character in reactions with these metals than isopropanol, thus its reactions with the metals were faster. Reduction in the acidic character of isopropanol, a secondary alcohol, could be due to the existence off more alkyl groups in the molecule which displays +1 inductive effect. For the same alcohol the metals reactions were found to decrease with increase in electronegativity of the metals. Sodium being the least electronegative metal reacted fasted while tin the more electronegative metal reacted slowest. Mg, Al and Sn required a catalyst,, mercury (II) chloride and heat in order to initiate and drive the reactions completion. The alkoxides formed were found to be soluble to a certain extent in the tow alcohols and the order of solubility is such that Sn≥ Al ≥ Mg ≥ Na.(Author)

  4. Synthesis and characterization of sodium alkoxides

    Indian Academy of Sciences (India)

    K Chandran; R Nithya; K Sankaran; A Gopalan; V Ganesan

    2006-04-01

    Alcohol route is being adopted for cleaning sodium from sodium-wetted small components of coolant circuits of fast reactors. For better understanding of sodium–alcohol reactions and their energetics, the data on thermo-chemical properties such as heats of sodium–alcohol reactions, heats of dissolution, heat capacities, thermal decomposition behaviour, etc of their end products are essential. In order to generate such data, high purity sodium alkoxides, viz. sodium methoxide, sodium ethoxide and sodium -propoxide, were prepared by reacting sodium metal with respective alcohol. These compounds were characterized using X-ray diffraction technique and IR spectroscopy. The elemental analysis was carried out by CHNS analyser and atomic emission spectroscopy. Normal chain sodium alkoxides were found to exhibit tetragonal crystal structure. Crystal structures of sodium ethoxide and sodium -propoxide are reported for the first time. The IR spectrum of sodium -propoxide is also reported for the first time.

  5. Reactions of ketones with uranium tetraborohydride, mechanism and stereoselectivity, synthesis and structure of uranium (IV) tetrahydroborato alkoxide complexes

    International Nuclear Information System (INIS)

    The mono- and bisalkoxide uranium complexes U(BH4)3(OCHR1R2)(THF)2 1 and U(BH4)2(OCHR1R2)2(THF)2 2 were prepared successively in tetrahydrofuran (THF) by treatment of U(BH4)4 with the corresponding ketone R1R2C = O (acetone, benzophenone, cyclohexanone, 2-methylcyclohexanone, 4-tert-butylcyclohexanone, and norcamphor). The borane BH3.THF was liberated during the formation of 1 and 2, and reacted with the ketone to give the alkoxyborane species B(OCHR1R2)nH3-n. Formation of 1 also resulted from: a) reaction of U-BH4)4 with the alkoxyborane species; b) reaction of U(BH4)4 with 2; and c) reaction of 2 with BH3.THF. The alkoxide groups of 1 and 2 rapidly exchange with those of the alkoxyborane species. The uranium complexes 1 and alkoxyborane species resulting from the reaction of U(BH4)4 with the substituted cyclohexanones or norcamphor have been separated and their hydrolysis afforded the corresponding epimeric alcohols in different proportions. The monoalkoxide compounds 1 were alternatively prepared by reaction of the ketones R1R2C = O with UCl4 in the presence of LiBH4 or by treatment of U(BH4)4 with the alcohols R1R2CHOH. The octahedral crystal structures of U(BH4)3(OCHPh2)(THF)2 1b and U(BH4)2(OCHPh2)2(THF)2 2b show that in 1b, the two equatorial THF ligands (and the two equatorial BH4 groups) are in relative cis positions whereas they are trans in 2b

  6. Synthesis and structural properties of ultra-small oxide (TiO2, ZrO2, SnO2) nanoparticles prepared by decomposition of metal alkoxides

    International Nuclear Information System (INIS)

    The decomposition of metal (Ti, Zr, Sn) alkoxides at 250 deg. C in a solution of tetradecene and dodecylamine resulted in the formation of ultra-small (1-2 nm) oxide nanoparticles. The nanoparticles showed unusual structural properties. The high-pressure orthorhombic phase was found for SnO2. The as-synthesized ZrO2 nanoparticles were only partially crystallized. It was possible to observe their in situ crystallization under the TEM beam. The TiO2 nanoparticles appeared amorphous, with only a few nanocrystals dispersed in the sample. The temperature evolution of the samples was investigated in situ by Raman spectroscopy. All SnO2 was converted to stable cassiterite at 350 deg. C. TiO2 and ZrO2 samples displayed phase stability reversal over a broad range of temperatures.

  7. Synthesis and Characterization of Fluoro- and Chlorobimetallic Alkoxides as Precursors for Luminescent Metal Oxide Materials via Sol-Gel Technique

    Institute of Scientific and Technical Information of China (English)

    ATHAR, Taimur; SEOK, Sang II; KWON, Jeong Oh

    2007-01-01

    Heterobimetallic alkoxides are broadly recognized as versatile precursors for luminescence materials, and efforts are being made to develop novel routes by applying the concept of geometrical molecular design, for their synthesis and to design a single source precursor suited to photoluminescent materials. Novel and new series of bimetallic alkoxides has been prepared by metathesis route. They exhibit a lower sensitivity towards hydrolysis and so they are easier to handle as compared to other alkoxides. All the compounds were characterized by elemental analysis, FT-IR and multinuclear NMR spectroscopies. FT-IR revealed that the molecular structure of these metal spectroscopy provided useful information about chemical shifts for better understanding the likely structure based on interactions with their coordinate metals. The mass spectra show similar types of fragmentation pattern.SEM-EDS analyses showed consistency with the formulation. XRD patterns show an enhanced homogeneity at high temperature. TGA measurements show that thermal decomposition occured in steps that depended entirely on the chemical compositions and the synthesis routes. SEM observation reveals that the morphology and particle size strongly depend on synthesis routes for their precursors.

  8. Synthesis of Industrially Relevant Carbamates towards Isocyanates using Carbon Dioxide and Organotin(IV) Alkoxides.

    Science.gov (United States)

    Germain, Nicolas; Müller, Imke; Hanauer, Matthias; Paciello, Rocco A; Baumann, Robert; Trapp, Oliver; Schaub, Thomas

    2016-07-01

    A straightforward phosgene-free synthesis of aromatic isocyanates and diisocyanates is disclosed. Theoretical investigations suggested that the insertion of carbon dioxide (CO2 ) by dialkyltin(IV) dialkoxides could be used to convert aromatic amines into aromatic mono- and dicarbamates. Here we show, that methyl phenylcarbamate (MPC) from aniline using organotin(IV) dimethoxide and CO2 can be formed in high yield of up to 92 %, experimentally corroborating the predictions of density functional theory (DFT) calculations. MPC was then separated from the tin oxide residues and converted into phenyl isocyanate. Furthermore, organotin(IV) alkoxides could be regenerated from the tin oxide residues and reused, paving the way for a continuous industrial process. Extension of the scope to the synthesis of diurethanes from toluene 2,4-diamine and 4,4'-methylenedianiline could potentially allow the efficient production of industrially relevant diisocyanates. PMID:27319978

  9. Modification of zirconium and hafnium alkoxides : the effect of molecular structure on derived materials

    OpenAIRE

    Spijksma, Gerald Iwan

    2006-01-01

    This thesis deals with the influence of modifying ligands on the structure and stability of zirconium and hafnium precursors. The applicability of the obtained modified alkoxides has been evaluated for MOCVD and sol-gel. Furthermore, the influence of the introduction of heteroligands on the sol-gel process and their effect on the derived materials has been addressed. A specific focus has been on the preparation of microporous materials by sol-gel for the application in membranes.

  10. Syntheses, Structures and Thermal Studies of Fluorinated and Non-Fluorinated Homo and Heterometallic Alkoxides

    Science.gov (United States)

    Samuels, John Andrew

    The following studies probe the effects of ligand structure and modification on the conversion of metal species to solid-state products. 1. The synthesis, characterization, thermal decomposition, and full hydrolysis of rm Cu^{I }_2 Zr_2(O^{i}Pr) _{10} (1), Cu^ {rm I}_4Zr_4 O(O^{rm i}Pr) _{18} (2), and Cu ^{rm II}_4Zr _4O_3(O^ {rm i}Pr)_{18 } (3) are reported. The structure of 1 contains a Zr_2(O^{rm i}Pr)_9^- face -sharing bioctahedron bound to a Cu^{ rm I}_2(mu_2-OR) ^+ fragment via two mu _2 -alkoxides. The structure for 2 contains two (C_2(mu_2-OR) _2Zr_2(mu_2 -OR)_3(OR)_4] ^{1-} fragments connected via a pseudo-tetrahedral mu_4-O ^{2-} ligand. The structure of 3 contains a planar Cu_4O(O ^{rm i}Pr)_2 ^{4+} fragment capped by two Zr _2O(O^{rm i}Pr)_8^{2-} face-sharing bioctahedral units. The central oxo of the copper fragment is square-planar. TGA studies of ClCuZr_2(O^{ rm i}Pr)_9, 1, 2, and 3 show that internal redox occurs, producing copper metal, acetone, and isopropanol. The final products contain an increasing amount of zirconia with increasing number of oxo ligands in the precursor species. Full hydrolysis of 1 and 3, followed by thermolysis, produces Cu ^0, Cu_2O, and CuO with zirconia, depending on thermolysis conditions. 2. The compounds Na(HFIP) (HFIP = OCH(CF _3)_2), 1a, Na(TFTB) (TFTB = OC(CH _3)_2(CF_3 )), 1b, Na(HFTB) (HFTB = OC(CH_3 )(CF_3)_2), 1c, Na(PFTB) (PFTB = OC(CF_3)_3), 1d, Zr(HFIP)_4, 2a, Zr(TFTB) _4, 2b, Zr(HFTB)_4, 2c, Zr(PFTB)_4, 2d, Na_2 Zr(OR_{rm f})_6 (C_6H_6)_ {rm n} (3a when n = 1 and 3b when n = 2), and Tl_2Zr(OR_ {rm f})_6, 4, have been synthesized and characterized by mass spectrometry, multinuclear NMR and (for 1a, 2c, 3a, 3b and 4) X-ray diffraction structure determinations. Intramolecular bonding interactions between organofluorines and sodium or thallium are seen in all structures and are supported by Tl/F coupling in ^{205}Tl and ^{19 }F NMR spectra. Chemical vapor depositions of 1a-d, 2b-d and 3 produce metal fluoride

  11. New inorganic (an)ion exchangers based on Mg–Al hydrous oxides: (Alkoxide-free) sol–gel synthesis and characterisation

    NARCIS (Netherlands)

    Chubar, N.

    2011-01-01

    New inorganic ion exchangers based on double Mg–Al hydrous oxides were generated via the new non-traditional sol–gel synthesis method which avoids using metal alkoxides as raw materials. Surface chemical and adsorptive properties of the final products were controlled by several ways of hydrogels and

  12. Alcohol adducts of alkoxides: Intramolecular hydrogen bonding as a general structural feature

    International Nuclear Information System (INIS)

    Characterization of Zr2(OiPr)8(iPrOH)2 by 1H and 13C NMR spectroscopy, ir spectroscopy, and single-crystal x-ray diffraction (-100 degree C) is reported. The unit cell contains four half-dimers in the asymmetric unit, all of which differ only in the rotational conformation about Zr-O and O-C bonds. In each dimer, the edge-shared bioctahedron has two μ-OiPr groups. On opposite sides of this Zr2(μ-OR)2 plane, each dimer forms two hydrogen bonds, one each between a coordinated alcohol and a terminal alkoxide. The NMR spectra at 25 degree C are so simple as to be structurally uninformative, a result of rapid fluxionality which includes, as one component, proton migration among all OiPr units. At -80 degree C in toluene, the NMR spectra are now too complex to be accounted for by a single edge-shared bioctahedral structure. The hafnium analogue is isomorphous with the zirconium compound. Although Ce2(OiPr)8(iPrOH)2 is not isomorphous, it exhibits an analogous hydrogen-bonded structure in which the O hor-ellipsis O distance is as short as it is in the Zr analogue, in spite of a metal-metal separation which is longer by 0.28 angstrom. The generality of hydrogen bonding between M-OR and M-O(H)R groups when they are aligned parallel in a metal cluster is reviewed. 44 refs., 2 figs., 4 tabs

  13. New inorganic (an)ion exchangers based on Mg–Al hydrous oxides: (Alkoxide-free) sol–gel synthesis and characterisation

    KAUST Repository

    Chubar, Natalia

    2011-05-01

    New inorganic ion exchangers based on double Mg-Al hydrous oxides were generated via the new non-traditional sol-gel synthesis method which avoids using metal alkoxides as raw materials. Surface chemical and adsorptive properties of the final products were controlled by several ways of hydrogels and xerogels treatments which produced the materials of the layered structure, mixed hydrous oxides or amorphous adsorbents. The final adsorptive materials obtained via thermal treatment of xerogels were the layered mesoporous materials with carbonate in the interlayer space, surface abundance with hydroxylic groups and maximum adsorptive capacity to arsenate. Higher affinity of Mg-Al hydrous oxides towards H2AsO4- is confirmed by steep adsorption isotherms having plateau (removal capacity) at 220. mg[As]. gdw-1 for the best sample at pH = 7, fast adsorption kinetics and little pH effect. Adsorption of arsenite, fluoride, bromate, bromide, selenate, borate by Mg-Al hydrous oxides was few times high either competitive (depending on the anion) as compare with the conventional inorganic ion exchange adsorbents. © 2011 Elsevier Inc.

  14. Synthesis of Yttria-Stabilized Zirconia Aerogels by a Non-Alkoxide Sol-Gel Route

    Energy Technology Data Exchange (ETDEWEB)

    Chervin, C N; Clapsaddle, B J; Chiu, H W; Gash, A E; Satcher, Jr., J H; Kauzlarich, S M

    2005-02-11

    Homogeneous, nanocrystalline powders of yttria-stabilized zirconia were prepared using a nonalkoxide sol-gel method. Monolithic gels, free of precipitation, were prepared by addition of propylene oxide to aqueous solutions of Zr{sup 4+} and Y{sup 3+} chlorides at room temperature. The gels were dried with supercritical CO{sub 2}(l), resulting in amorphous aerogels that crystallized into cubic stabilized ZrO{sub 2} following calcination at 500 C. The aerogels and resulting crystalline products were characterized using in-situ temperature profile X-ray diffraction, thermal analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and nitrogen adsorption/desorption analysis. TEM and N{sub 2} adsorption/desorption analysis of an aerogel indicated a porous network structure with a high surface area (409 m{sup 2}/g). The crystallized yttria-stabilized zirconia maintained high surface area (159 m{sup 2}/g) upon formation of homogeneous, nanoparticles ({approx}10 nm). Ionic conductivity at 1000 C of sintered YSZ (1500 C, 3 hours) prepared by this method, was 0.13 {+-} 0.02 {Omega}{sup -1} cm{sup -1}. Activation energies for the conduction processes from 1000-550 C and 550-400 C, were 0.95 {+-} 0.09 and 1.12 {+-} 0.05 eV, respectively. This is the first reported synthesis and characterization of yttria-stabilized zirconia via an aerogel precursor.

  15. Synthesis of a mononuclear, non-square-planar chromium(ii) bis(alkoxide) complex and its reactivity toward organic carbonyls and CO2.

    Science.gov (United States)

    Yousif, Maryam; Cabelof, Alyssa C; Martin, Philip D; Lord, Richard L; Groysman, Stanislav

    2016-06-14

    In this paper, we report the synthesis and reactivity of a rare mononuclear chromium(ii) bis(alkoxide) complex, Cr(OR')2(THF)2, that is supported by a new bulky alkoxide ligand (OR' = di-t-butyl-(3,5-diphenylphenyl)methoxide). The complex is prepared by protonolysis of square-planar Cr(N(SiMe3)2)2(THF)2 with HOR'. X-ray structure determination disclosed that Cr(OR')2(THF)2 features a distorted seesaw geometry, in contrast to nearly all other tetra-coordinate Cr(ii) complexes, which are square-planar. The reactivity of Cr(OR')2(THF)2 with aldehydes, ketones, and carbon dioxide was investigated. Treatment of Cr(OR')2(THF)2 with two equivalents of aromatic aldehydes ArCHO (ArCHO = benzaldehyde, 4-anisaldehyde, 4-trifluorbenzaldehyde, and 2,4,6-trimethylbenzaldehyde) leads cleanly to the formation of Cr(iv) diolate complexes Cr(OR')2(O2C2H2Ar2) that were characterized by UV-vis and IR spectroscopies and elemental analysis; the representative complex Cr(OR')2(O2C2H2Ph2) was characterized by X-ray crystallography. In contrast, no reductive coupling was observed for ketones: treatment of Cr(OR')2(THF)2 with one or two equivalents of benzophenone forms invariably a single ketone adduct Cr(OR')2(OCPh2) which does not react further. QM/MM calculations suggest the steric demands prevent ketone coupling, and demonstrate that a mononuclear Cr(iii) bis-aldehyde complex with partially reduced aldehydes is sufficient for C-C bond formation. The reaction of Cr(OR')2(THF)2 with CO2 leads to the insertion of CO2 into a Cr-OR' bond, followed by complex rearrangement to form a diamagnetic dinuclear paddlewheel complex Cr2(O2COR')4(THF)2, that was characterized by NMR, UV-vis, and IR spectroscopy, and X-ray crystallography. PMID:27073074

  16. Synthesis of a mononuclear, non-square-planar chromium(ii) bis(alkoxide) complex and its reactivity toward organic carbonyls and CO2.

    Science.gov (United States)

    Yousif, Maryam; Cabelof, Alyssa C; Martin, Philip D; Lord, Richard L; Groysman, Stanislav

    2016-06-14

    In this paper, we report the synthesis and reactivity of a rare mononuclear chromium(ii) bis(alkoxide) complex, Cr(OR')2(THF)2, that is supported by a new bulky alkoxide ligand (OR' = di-t-butyl-(3,5-diphenylphenyl)methoxide). The complex is prepared by protonolysis of square-planar Cr(N(SiMe3)2)2(THF)2 with HOR'. X-ray structure determination disclosed that Cr(OR')2(THF)2 features a distorted seesaw geometry, in contrast to nearly all other tetra-coordinate Cr(ii) complexes, which are square-planar. The reactivity of Cr(OR')2(THF)2 with aldehydes, ketones, and carbon dioxide was investigated. Treatment of Cr(OR')2(THF)2 with two equivalents of aromatic aldehydes ArCHO (ArCHO = benzaldehyde, 4-anisaldehyde, 4-trifluorbenzaldehyde, and 2,4,6-trimethylbenzaldehyde) leads cleanly to the formation of Cr(iv) diolate complexes Cr(OR')2(O2C2H2Ar2) that were characterized by UV-vis and IR spectroscopies and elemental analysis; the representative complex Cr(OR')2(O2C2H2Ph2) was characterized by X-ray crystallography. In contrast, no reductive coupling was observed for ketones: treatment of Cr(OR')2(THF)2 with one or two equivalents of benzophenone forms invariably a single ketone adduct Cr(OR')2(OCPh2) which does not react further. QM/MM calculations suggest the steric demands prevent ketone coupling, and demonstrate that a mononuclear Cr(iii) bis-aldehyde complex with partially reduced aldehydes is sufficient for C-C bond formation. The reaction of Cr(OR')2(THF)2 with CO2 leads to the insertion of CO2 into a Cr-OR' bond, followed by complex rearrangement to form a diamagnetic dinuclear paddlewheel complex Cr2(O2COR')4(THF)2, that was characterized by NMR, UV-vis, and IR spectroscopy, and X-ray crystallography.

  17. Synthesis, Radical Reactivity, and Thermochemistry of Monomeric Cu(II) Alkoxide Complexes Relevant to Cu/Radical Alcohol Oxidation Catalysis.

    Science.gov (United States)

    Porter, Thomas R; Capitao, Dany; Kaminsky, Werner; Qian, Zhaoshen; Mayer, James M

    2016-06-01

    Two new monomeric Cu(II) alkoxide complexes were prepared and fully characterized as models for intermediates in copper/radical mediated alcohol oxidation catalysis: Tp(tBuR)Cu(II)OCH2CF3 with Tp(tBu) = hydro-tris(3-tert-butyl-pyrazol-1-yl)borate 1 or Tp(tBuMe) = hydro-tris(3-tert-butyl-5-methyl-pyrazol-1-yl)borate 2. These complexes were made as models for potential intermediates in enzymatic and synthetic catalytic cycles for alcohol oxidation. However, the alkoxide ligands are not readily oxidized by loss of H; instead, these complexes were found to be hydrogen atom acceptors. They oxidize the hydroxylamine TEMPOH, 2,4,6-tri-t-butylphenol, and 1,4-cyclohexadiene to the nitroxyl radical, phenoxyl radical, and benzene, with formation of HOCH2CF3 (TFE) and the Cu(I) complexes Tp(tBuR)Cu(I)-MeCN in dichloromethane/1% MeCN or 1/2 [Tp(tBuR)Cu(I)]2 in toluene. On the basis of thermodynamics and kinetics arguments, these reactions likely proceed through concerted proton-electron transfer mechanisms. Thermochemical analyses give lower limits for the "effective bond dissociation free energies (BDFE)" of the O-H bonds in 1/2[Tp(tBuR)Cu(I)]2 + TFE and upper limits for the free energies associated with alkoxide oxidations via hydrogen atom transfer (effective alkoxide α-C-H BDFEs). These values are summations of the free energies of multiple chemical steps, which include the energetically favorable formation of 1/2[Tp(tBuR)Cu(I)]2. The effective alkoxide α-C-H bonds are very weak, BDFE ≤ 38 ± 4 kcal mol(-1) for 1 and ≤44 ± 5 kcal mol(-1) for 2 (gas-phase estimates), because C-H homolysis is thermodynamically coupled to one electron transfer to Cu(II) as well as the favorable formation of the 1/2[Tp(tBuR)Cu(I)]2 dimer. Treating 1 with the H atom acceptor (t)Bu3ArO(•) did not result in the expected alkoxide oxidation to an aldehyde, but rather net 2,2,2-trifluoroethoxyl radical transfer occurred to generate an unusual 2-substituted dienone-ether product. Treating 2

  18. Electronic Structure of a Cu(II)-Alkoxide Complex Modeling Intermediates in Copper-Catalyzed Alcohol Oxidations.

    Science.gov (United States)

    Hayes, Ellen C; Porter, Thomas R; Barrows, Charles J; Kaminsky, Werner; Mayer, James M; Stoll, Stefan

    2016-03-30

    In the copper-catalyzed oxidation of alcohols to aldehydes, a Cu(II)-alkoxide (Cu(II)-OR) intermediate is believed to modulate the αC-H bond strength of the deprotonated substrate to facilitate the oxidation. As a structural model for these intermediates, we characterized the electronic structure of the stable compound Tp(tBu)Cu(II)(OCH2CF3) (Tp(tBu) = hydro-tris(3-tert-butyl-pyrazolyl)borate) and investigated the influence of the trifluoroethoxide ligand on the electronic structure of the complex. The compound exhibits an electron paramagnetic resonance (EPR) spectrum with an unusually large gzz value of 2.44 and a small copper hyperfine coupling Azz of 40 × 10(-4) cm(-1) (120 MHz). Single-crystal electron nuclear double resonance (ENDOR) spectra show that the unpaired spin population is highly localized on the copper ion (≈68%), with no more than 15% on the ethoxide oxygen. Electronic absorption and magnetic circular dichroism (MCD) spectra show weak ligand-field transitions between 5000 and 12,000 cm(-1) and an intense ethoxide-to-copper charge transfer (LMCT) transition at 24,000 cm(-1), resulting in the red color of this complex. Resonance Raman (rR) spectroscopy reveals a Cu-O stretch mode at 592 cm(-1). Quantum chemical calculations support the interpretation and assignment of the experimental data. Compared to known Cu(II)-thiolate and Cu(II)-alkylperoxo complexes from the literature, we found an increased σ interaction in the Cu(II)-OR bond that results in the spectroscopic features. These insights lay the basis for further elucidating the mechanism of copper-catalyzed alcohol oxidations. PMID:26907976

  19. Metal alkoxides as starting materials for hydrolysis processes

    International Nuclear Information System (INIS)

    In this thesis the preparation of some metal alkoxides and their hydrolysis products were studied. The characteristic of each prepared alkoxides and their hydrolyzates were determined. Tetra ethoxysilane was prepared by the elemental route (the reaction of silicon powder with liquid ethanol) in the presence of tin ethoxide as a catalyst. The use of tin alkoxide is considered one of the most developed ways used recently in chemistry, compared to the usage of acids and bases as catalyst previously. It had been confirmed by the usage of (infrared) IR spectroscopy, the structure of the prepared material. Also tin isopropoxide had been prepared and hydrolyzed. Ethoxides of aluminium, magnesium and tin had been prepared by the elemental route. The gelation product had been analyzed. tetraethoxysilane had been also prepared by the halosilane route. Isopropoxide of each aluminium, magnesium and tin had been synthesized, hydrolyzed, allowed to gel and analyzed by IR (infrared) spectroscopy and gas-liquid chromatography. However, results obtained indicated that tin ethoxide is an effective catalyst in the direct synthesis of tetraethoxysilane from silicon powder and liquid ethanol. Gas-liquid chromatography, infra-red (IR) analysis showed that the final reaction product was tetraethoxysilane. (Author)

  20. Titanium alkoxide compound

    Science.gov (United States)

    Boyle, Timothy J.

    2007-08-14

    A titanium alkoxide composition is provided, as represented by the chemical formula (OC.sub.6H.sub.5N).sub.2Ti(OC.sub.6H.sub.5NH.sub.2).sub.2. As prepared, the compound is a crystalline substance with a hexavalent titanium atom bonded to two OC.sub.6H.sub.5NH.sub.2 groups and two OC.sub.6H.sub.5N groups with a theoretical molecular weight of 480.38, comprising 60.01% C, 5.04% H and 11.66% N.

  1. Alkoxide routes to Inorganic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, George H [ORNL

    2007-12-01

    An all alkoxide solution chemistry utilizing metal 2-methoxyethoxide complexes in 2-methoxyethanol was used to deposit thin-films of metal oxides on single-crystal metal oxide substrates and on biaxially textured metal substrates. This same chemistry was used to synthesize complex metal oxide nanoparticles. Nuclear Magnetic Resonance spectroscopy was used to study precursor solutions of the alkaline niobates and tantalates. Film crystallization temperatures were determined from x-ray diffraction patterns of powders derived from the metal oxide precursor solutions. Film structure was determined via x-ray diffraction. Film morphology was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Epitaxial thin-films of strontium bismuth tantalate (SrBi{sub 2}Ta{sub 2}O{sub 9}, SBT) and strontium bismuth niobate (SrBi{sub 2}Nb{sub 2}O{sub 9}, SBN) were deposited on single crystal [1 0 0] magnesium oxide (MgO) buffered with lanthanum manganate (LaMnO{sub 3}, LMO). Epitaxial thin films of LMO were deposited on single crystal [100] MgO via Rf-magnetron sputtering and on single crysal [100] lanthanum aluminate (LaAlO{sub 3}) via the chemical solution deposition technique. Epitaxial thin-films of sodium potassium tantalate (na{sub 0.5}K{sub 0.5}TaO{sub 3}, NKT), sodium potassium niobate (Na{sub 0.5}K{sub 0.5}NbO{sub 3}, NKN) and sodium potassium tantalum niobate (Na{sub 0.5}K{sub 0.5}Ta{sub 0.5}O{sub 3}, NKTN) were deposited on single crystal [1 0 0] lanthanum aluminate and [1 0 0] MgO substrates (NKT and NKN) and biaxially textured metal substrates via the chemical solution deposition technique. Epitaxial growth of thin-films of NKT, NKN and NKTN was observed on LAO and Ni-5% W. Epitaxial growth of thin-films of NKN and the growth of c-axis aligned thin-films of NKT was observed on MgO. Nanoparticles of SBT, SBN, NKT and NKN were synthesized in reverse micelles from alkoxide precursor solutions. X-ray diffraction and transmission electron

  2. I. Synthesis and characterization of volatile uranium(V) and uranium(VI) alkoxides. II. Isotope selective infrared photochemistry of uranium(VI) hexamethoxide

    International Nuclear Information System (INIS)

    I. A number of uranium(V) and uranium(VI) alkoxides were prepared and characterized, with particular attention to volatility and vibrational spectroscopy. Volatility data and x-ray crystallography implied the uranium(V) complexes to be associated as dimers or higher polymers. The uranium(VI) alkoxides were determined to be monomeric through similar considerations. A detailed discussion of uranium hexamethoxide vibrational data is given, with regard to its suitability for infrared laser photolysis with a CO2-TEA laser. II. Infrared laser photolysis of uranium hexamethoxide was shown to selectively dissociate the 238U containing species, when irradiated with a CO2-TEA laser. Wavelength and fluence dependencies were measured, yielding an optimum 235U enrichment factor (for the unreacted material) of 1.0335 on the P(38)/10.6 μ laser transition at 3.2 J/cm2. A selectivity of 1.5 was calculated from dissociation yield experiments. The photolysis products were analyzed, and the initial reaction was determined to be methoxy radical elimination. Secondary reaction products, in the form of polymethoxy ethers, appear to be the result of intramolecuar reactions (on the uranium substrate) initiated by collisional processes. Several mechanisms are proposed

  3. A planar oxocuprate(II) array via heterometallic alkoxide chemistry

    International Nuclear Information System (INIS)

    Application of the molecular precursor method to the synthesis of copper-based high-temperature superconductors rests on the authors ability to produce copper containing heterometallic alkoxides. They have reported recently on the chemistry of the anion Zr2-(OiPr)9-, which is related to recent reports by the group of Mehrotra. They report here their investigation of the coupling of this and related anions to CuCl2 of relevance to hydrolytic routes to copper/oxo superconductors

  4. Applications versus properties of Mg–Al layered double hydroxides provided by their syntheses methods: Alkoxide and alkoxide-free sol–gel syntheses and hydrothermal precipitation

    KAUST Repository

    Chubar, Natalia

    2013-12-01

    A tremendous number of studies have examined layered double hydroxides (LDH) for their technological applications in the ion exchange removal of toxic ions, recovery of valuable substances, catalysis, CO2 capture, as a layered host for storage/delivery of biologically active molecules, additives to plastics and building materials, and other functions. Numerous publications always conclude that the materials (prepared, as a rule, using the oldest synthesis method) are very promising for each investigated application; however, the main chemical industries producing these materials advertise them mainly (or only) as plastic additives. The authors performed extensive research using many of the appropriate methods to compare the structure, surface and adsorptive properties of three Mg-Al LHDs produced by advanced synthesis methods. One industrial sample (by Sasol, Germany) prepared by the alkoxide sol-gel method and two novel Mg-Al LDHs synthesised in-house by alkoxide-free sol-gel and hydrothermal precipitation approaches were investigated. Reasons for the very different adsorptive selectivity of the three LDHs towards arsenate, selenate, phosphate, arsenite and selenite have been provided, highlighting the role of speciation of the interlayer carbonate, aluminium, magnesium, interlayer hydration and moisture content in the adsorptive selectivity towards each toxic anion. This work is the first report presenting the regularities of the LDHs structure, surface and anion exchange properties as a function of their syntheses method. It establishes the links to potential technological applications of each investigated LDH and explains the necessary properties required to make the technological application cost-effective and efficient. The paper might accelerate industrial applications of these advanced materials. © 2013 Elsevier B.V.

  5. A planar oxocuprate(II) array via heterometallic alkoxide chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Samuels, J.A.; Vaarttra, B.A.; Huffman, J.C.; Trojan, K.L.; Hatfield, W.E.; Caulton, K.G. (Indiana Univ., Bloomington (United States) Univ. of North Carolina, Chapel Hill (United States))

    1990-12-19

    Application of the molecular precursor method to the synthesis of copper-based high-temperature superconductors rests on the authors ability to produce copper containing heterometallic alkoxides. They have reported recently on the chemistry of the anion Zr{sub 2}-(O{sup i}Pr){sub 9}{sup {minus}}, which is related to recent reports by the group of Mehrotra. They report here their investigation of the coupling of this and related anions to CuCl{sub 2} of relevance to hydrolytic routes to copper/oxo superconductors.

  6. Control Augmented Structural Synthesis

    Science.gov (United States)

    Lust, Robert V.; Schmit, Lucien A.

    1988-01-01

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

  7. Water-soluble titanium alkoxide material

    Science.gov (United States)

    Boyle, Timothy J.

    2010-06-22

    A water soluble, water stable, titanium alkoxide composition represented by the chemical formula (OC.sub.6H.sub.6N).sub.2Ti(OC.sub.6H.sub.2(CH.sub.2N(CH.sub.3).sub.2).sub- .3-2,4,6).sub.2 with a theoretical molecular weight of 792.8 and an elemental composition of 63.6% C, 8.1% H, 14.1% N, 8.1% O and 6.0% Ti.

  8. Structural synthesis of parallel robots

    CERN Document Server

    Gogu, Grigore

    This book represents the fifth part of a larger work dedicated to the structural synthesis of parallel robots. The originality of this work resides in the fact that it combines new formulae for mobility, connectivity, redundancy and overconstraints with evolutionary morphology in a unified structural synthesis approach that yields interesting and innovative solutions for parallel robotic manipulators.  This is the first book on robotics that presents solutions for coupled, decoupled, uncoupled, fully-isotropic and maximally regular robotic manipulators with Schönflies motions systematically generated by using the structural synthesis approach proposed in Part 1.  Overconstrained non-redundant/overactuated/redundantly actuated solutions with simple/complex limbs are proposed. Many solutions are presented here for the first time in the literature. The author had to make a difficult and challenging choice between protecting these solutions through patents and releasing them directly into the public domain. T...

  9. Ti(IV) and Zr(IV) alkoxy complexes with O-donor ligands. Synthesis, structural characterization and applications

    International Nuclear Information System (INIS)

    alkoxy groups by β-diketonate ligands in the alkoxide/β-diketonate molar ratio of 1:1 makes possible the synthesis of monomeric complexes of the general formula [Ti(OR)2 (β-diketonate) 2]. The use of an excess of β-diketonate (1:2) leads to the formation of dimeric complexes ([Ti(OR)3(β-diketonate)] 2. Sensitivity of these compounds to moisture was significant lower than the parent Ti(IV) alkoxides. Suitable volatility of the mentioned complexes and thermal decomposition to TiO2 caused that their use as CVD precursors is possible. Deposition experiments proved that pure TiO2 layers of anatase form were obtained at temperatures higher than 573 K using [Ti(dpm)2 (OiPr)v] and [Ti(mpd)(mdop)(m-OMe)] 2 as precursors. >From Zr(IV) β-diketonate derivatives, only [Zr(OR2 (thd)2] (R = OiPr, tBu) and [Zr(OiPr)3(thd)] 2 were used for the deposition of ZrO2 by CVD methods [98]. According to the literature reports, above mentioned β-diketonates were less reactive and easier to handle than parent alkoxides, but their volatility was significantly lower. ZrO2 layers were also prepared using [Zr(acac)2 (hfip)2] but in deposited films, traces of fluorine contaminations were observed. Oxo-alkoxy carboxylate Ti(IV) derivatives were synthesized in reactions of Ti(IV) alkoxides with carboxylic acids. The structure of these complexes consists of oxo-metallic skeletons, which size and structure depends on (a) metal alkoxide/carboxylic acid molar ratio, (b) type of alkoxide and carboxylate ligand, and (c) reaction temperature. Results of these works suggest that Ti(IV) complexes, which structure consists of [Ti6O6(OR4)6(OOCR')6] (R OiPr, nBu, iBu, R' = H, Me, tBu, CH2tBu, C(CH3)2Et, C6H4Oph) clusters are the most stable. These types of Ti(IV) complexes were also prepared in the reaction of Ti(IV) trimethylsiloxide with 2 fold exces of organic acids. Thermolysis of [Ti6O6(OR4)6(OOCR')6] proceeds with their partially decomposition and formation of a volatile and stable Ti(IV) alkoxide and

  10. I. Synthesis and characterization of volatile uranium(VI) alkoxides for laser-induced uranium isotope separation. II. Synthesis and characterization of octaalkyl metallo and metal-free phthalocyanines, decaalkyl uranyl superphthalocyanines, and hemiporphyrazines

    International Nuclear Information System (INIS)

    Current efforts in laser-induced U isotope separation with emphasis on the synthesis of volatile U complexes suitable for selective multiphoton infrared excitation with a CO2 laser are discussed. Efficient one-step scalable syntheses of U hexamethoxide, U(OCH3)6, starting from the readily available UF6 and NaOCH3 or CH3Si(OCH3)3 are described. The solution phase electronic spectrum of U(OCH3)6 is interpreted in terms of both ligand- and solvent-to-metal charge transfer. The vibrational spectroscopy of U(OCH3)6 in solution and in the solid state is described, and the spectroscopic results for the complex in the 10 m region are presented and discussed in terms of the observed laser-induced photochemistry of U(OCH3)6. The vapor pressure of U(OCH3)6 was found to be 3 μ at 190C, increasing to 17 μ at 330C. The heat of sublimation, ΔH/sub '/, and entropy of sublimation, ΔS/sub '/, were meaured as 19 +- 4 kcal/mole and 58+-7 eu, respectively. A straightforward, efficient, and generalizable synthesis of symmetrically substituted 2,3,9,10,16,17,23,23-octaalkyl phthalocyanines and 2,3,9,10,16,17,23,24,30,31-decaalkyl uranyl superphthalocyanines from o-dialkyl benzenes is described. The synthesis is illustrated with methyl and n-butyl substituents, and the complexes are characterized by a variety of chemical and physiochemical methods. The preparation of other U complexes and of a macrocyclic compound that undergoes a metalation reaction with activated Ti, activated Mg, n-BuLi, and Li-di-tert-butylphenyl are described in 4 appendixes

  11. Thermal decomposition kinetics of sodium alkoxides - model independent method

    International Nuclear Information System (INIS)

    Sodium alkoxides namely sodium methoxide and sodium ethoxide were synthesized and characterized by various analytical techniques. Thermal decomposition of these compounds was studied under constant heating rate using thermogravimetric analyzer coupled with mass spectrometer (TGA-MS). On decomposition, these sodium alkoxides form gaseous products of saturated and unsaturated hydrocarbons and leave sodium carbonate, sodium hydroxide and free carbon as residue. Kinetic parameters namely activation energy and pre-exponential factor were deduced from the dynamic TGA data by physical model independent (iso-conversion) method. (author)

  12. Assessment of structural diversity in combinatorial synthesis.

    Science.gov (United States)

    Fergus, Suzanne; Bender, Andreas; Spring, David R

    2005-06-01

    This article covers the combinatorial synthesis of small molecules with maximal structural diversity to generate a collection of pure compounds that are attractive for lead generation in a phenotypic, high-throughput screening approach. Nature synthesises diverse small molecules, but there are disadvantages with using natural product sources. The efficient chemical synthesis of structural diversity (and complexity) is the aim of diversity-oriented synthesis, and recent progress is reviewed. Specific highlights include a discussion of strategies to obtain structural diversity and an analysis of molecular descriptors used to classify compounds. The assessment of how successful one synthesis is versus another is subjective, therefore we test-drive software to assess structural diversity in combinatorial synthesis, which is freely available via a web interface.

  13. Synthesis and Structural Revision of Cyslabdan.

    Science.gov (United States)

    Ohtawa, Masaki; Hishinuma, Yusuke; Takagi, Eiji; Yamada, Takafumi; Ito, Fumihiro; Arima, Shiho; Uchida, Ryuji; Kim, Yong-Pil; Ōmura, Satoshi; Tomoda, Hiroshi; Nagamitsu, Tohru

    2016-01-01

    Cyslabdan was isolated from the culture broth of Streptomyces sp. K04-0144 as a new potentiator of imipenem activity against methicillin-resistant Staphylococcus aureus. We accomplished the synthesis of cyslabdan according to a previously reported structure. However, we subsequently found that this structure was incorrect; our analysis of natural cyslabdan showed that it possessed R stereochemistry at the C8 position, not S, as had previously been reported. Thus, we completed the protecting-group-free synthesis of the correct structure of cyslabdan, which is described herein. PMID:27581641

  14. Mechanisms and kinetics of the hydrolysis and condensation of alkoxides

    OpenAIRE

    Schmidt, Helmut K.; Scholze, Horst

    1985-01-01

    Hydrolysis and condensation of alkoxides involve different reaction steps. Generally the first step is the dissolution of monomers in organic solvents like alcohols. The second step is hydrolysis, where in most cases condensation may not be separated. Dissolution may incorporate solvatation, coordination, complexation of polymerization. The addition of water leads to hydrolysis of Si-O-C bonds and subsequently condensation of silanoles takes place. Another possibility of reaction is the hydro...

  15. Heterolysis of Dihydrogen by Silver Alkoxides and Fluorides.

    Science.gov (United States)

    Tate, Brandon K; Nguyen, Jenna T; Bacsa, John; Sadighi, Joseph P

    2015-07-01

    Alkoxide-bridged disilver cations react with dihydrogen to form hydride-bridged cations, releasing free alcohol. Hydrogenolysis of neutral silver fluorides affords hydride-bridged disilver cations as their bifluoride salts. These reactions proceed most efficiently when the supporting ligands are expanded N-heterocyclic carbenes (NHCs) derived from 6- and 7-membered cyclic amidinium salts. Kinetics studies show that silver fluoride hydrogenolysis is first-order in both silver and dihydrogen.

  16. Structured synthesis of MEMS using evolutionary approaches

    DEFF Research Database (Denmark)

    Fan, Zhun; Wang, Jiachuan; Achiche, Sofiane;

    2008-01-01

    In this paper, we discuss the hierarchy that is involved in a typical MEMS design and how evolutionary approaches can be used to automate the hierarchical synthesis process for MEMS. The paper first introduces the flow of a structured MEMS design process and emphasizes that system-level lumped......-parameter model synthesis is the first step of the MEMS synthesis process. At the system level, an approach combining bond graphs and genetic programming can lead to satisfactory design candidates as system-level models that meet the predefined behavioral specifications for designers to trade off....... Then at the physical layout synthesis level, the selection of geometric parameters for component devices and other design variables is formulated as a constrained optimization problem and addressed using a constrained genetic algorithm approach. A multiple-resonator microsystem design is used to illustrate...

  17. Approximation concepts for efficient structural synthesis

    Science.gov (United States)

    Schmit, L. A., Jr.; Miura, H.

    1976-01-01

    It is shown that efficient structural synthesis capabilities can be created by using approximation concepts to mesh finite element structural analysis methods with nonlinear mathematical programming techniques. The history of the application of mathematical programming techniques to structural design optimization problems is reviewed. Several rather general approximation concepts are described along with the technical foundations of the ACCESS 1 computer program, which implements several approximation concepts. A substantial collection of structural design problems involving truss and idealized wing structures is presented. It is concluded that since the basic ideas employed in creating the ACCESS 1 program are rather general, its successful development supports the contention that the introduction of approximation concepts will lead to the emergence of a new generation of practical and efficient, large scale, structural synthesis capabilities in which finite element analysis methods and mathematical programming algorithms will play a central role.

  18. Synthesis, structure and luminescent properties of lanthanide fluoroalkoxides.

    Science.gov (United States)

    Kuzyaev, D M; Balashova, T V; Burin, M E; Fukin, G K; Rumyantcev, R V; Pushkarev, A P; Ilichev, V A; Grishin, I D; Vorozhtsov, D L; Bochkarev, M N

    2016-02-28

    Alkoxides [Ln(OR)3(DME)]2 (R = CH(CF3)2, Ln = Sm (1), Yb (2)), [Ce(OR)3(Phen)]2 (3) (Phen = 1,10-phenanthroline), [Ce(OR′)3(DME)2]2 (R′ = C(CF3)3) (4), {Gd(OR′)3(DME)2} (5), {Ln2[O(CF3)2C–C(CF3)2O]3} (Ln = Ce (6), Gd (7)), {Ce2[O(CF3)2C–C(CF3)2O]3(Phen)2} (8), and {Ce[O(CF3)2C–C(CF3)2O][O(CF3)2–C(CF3)2OH](Phen)2} (9) were synthesized by the reactions of silylamides Ln[N(SiMe3)2]3 with respective fluorinated alcohols. The heterovalent trinuclear complex {Sm2(μ2-OR)3(μ3-OR)2Sm(OR)2(THF)2.5(Et2O)0.5} (10) was obtained by treatment of SmI2(THF)2 with ROK. The reaction of europium(II) and yttrium(III) silylamides with ROH afforded the heterobimetallic alkoxide {Eu2(μ2-OR)3(μ3-OR)2Y(OR)2(DME)2} (11) containing divalent europium. The molecular structures of 1, 2, 3, 9, 10 and 11 were determined by X-ray analysis. All the prepared cerium derivatives as well as the europium–yttrium isopropoxide upon UV excitation exhibited photoluminescence in the regions of 370–425 (for Ce3+) and 485 nm (for Eu2+) which was assigned to 4d→5f transitions. PMID:26795570

  19. Xanthane sesquiterpenoids: structure, synthesis and biological activity.

    Science.gov (United States)

    Vasas, Andrea; Hohmann, Judit

    2011-04-01

    The aim of this review is to survey the naturally occurring xanthanes and xanthanolides, their structures, biological activities, structure–activity relationships and synthesis. There has been no comprehensive review of this topic previously. On the basis of 126 references, 112 compounds are summarized. PMID:21321751

  20. Synthesis and structures of metal chalcogenide precursors

    Science.gov (United States)

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

    1990-01-01

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

  1. Structures and Synthesis of Zwitterionic Polymers

    Directory of Open Access Journals (Sweden)

    André Laschewsky

    2014-05-01

    Full Text Available The structures and synthesis of polyzwitterions (“polybetaines” are reviewed, emphasizing the literature of the past decade. Particular attention is given to the general challenges faced, and to successful strategies to obtain polymers with a true balance of permanent cationic and anionic groups, thus resulting in an overall zero charge. Also, the progress due to applying new methodologies from general polymer synthesis, such as controlled polymerization methods or the use of “click” chemical reactions is presented. Furthermore, the emerging topic of responsive (“smart” polyzwitterions is addressed. The considerations and critical discussions are illustrated by typical examples.

  2. Superheavy nuclei – cold synthesis and structure

    Indian Academy of Sciences (India)

    Raj K Gupta

    2001-08-01

    The quantum mechanical fragmentation theory (QMFT), given for the cold synthesis of new and superheavy elements, is reviewed and the use of radioactive nuclear beams (RNB) and targets (RNT) is discussed. The QMFT is a complete theory of cold nuclear phenomena, namely, the cold fission, cold fusion and cluster radioactivity. Also, the structure calculations based on the axially deformed relativistic mean field (DRMF) approach are presented which predict new regions of spherical magicity, namely = 120 and = 172 or 184, for superheavy nuclei. This result is discussed in the light of recent experiments reporting the cold synthesis of = 118 element.

  3. Kinetics and Mechanism of Calcium Hydroxide Conversion into Calcium Alkoxides: Implications in Heritage Conservation Using Nanolimes.

    Science.gov (United States)

    Rodriguez-Navarro, Carlos; Vettori, Irene; Ruiz-Agudo, Encarnacion

    2016-05-24

    Nanolimes are alcohol dispersions of Ca(OH)2 nanoparticles used in the conservation of cultural heritage. Although it was believed that Ca(OH)2 particles were inert when dispersed in short-chain alcohols, it has been recently shown that they can undergo transformation into calcium alkoxides. Little is known, however, about the mechanism and kinetics of such a phase transformation as well as its effect on the performance of nanolimes. Here we show that Ca(OH)2 particles formed after lime slaking react with ethanol and isopropanol and partially transform (fractional conversion, α up to 0.08) into calcium ethoxide and isopropoxide, respectively. The transformation shows Arrhenius behavior, with apparent activation energy Ea of 29 ± 4 and 37 ± 6 kJ mol(-1) for Ca-ethoxide and Ca-isopropoxide conversion, respectively. High resolution transmission electron microscopy analyses of reactant and product phases show that the alkoxides replace the crystalline structure of Ca(OH)2 along specific [hkl] directions, preserving the external hexagonal (platelike) morphology of the parent phase. Textural and kinetic results reveal that this pseudomorphic replacement involves a 3D diffusion-controlled deceleratory advancement of the reaction front. The results are consistent with an interface-coupled dissolution-precipitation replacement mechanism. Analysis of the carbonation of Ca(OH)2 particles with different degree of conversion into Ca-ethoxide (α up to 0.08) and Ca-isopropoxide (α up to 0.04) exposed to air (20 °C, 80% relative humidity) reveals that Ca-alkoxides significantly reduce the rate of transformation into cementing CaCO3 and induce the formation of metastable vaterite, as opposed to stable calcite which forms in untransformed Ca(OH)2 samples. Similar effects are obtained when a commercial nanolime partially transformed into Ca-ethoxide is subjected to carbonation. Such effects may hamper/delay the strengthening or consolidation effects of nanolimes, thus having

  4. Kinetics and Mechanism of Calcium Hydroxide Conversion into Calcium Alkoxides: Implications in Heritage Conservation Using Nanolimes.

    Science.gov (United States)

    Rodriguez-Navarro, Carlos; Vettori, Irene; Ruiz-Agudo, Encarnacion

    2016-05-24

    Nanolimes are alcohol dispersions of Ca(OH)2 nanoparticles used in the conservation of cultural heritage. Although it was believed that Ca(OH)2 particles were inert when dispersed in short-chain alcohols, it has been recently shown that they can undergo transformation into calcium alkoxides. Little is known, however, about the mechanism and kinetics of such a phase transformation as well as its effect on the performance of nanolimes. Here we show that Ca(OH)2 particles formed after lime slaking react with ethanol and isopropanol and partially transform (fractional conversion, α up to 0.08) into calcium ethoxide and isopropoxide, respectively. The transformation shows Arrhenius behavior, with apparent activation energy Ea of 29 ± 4 and 37 ± 6 kJ mol(-1) for Ca-ethoxide and Ca-isopropoxide conversion, respectively. High resolution transmission electron microscopy analyses of reactant and product phases show that the alkoxides replace the crystalline structure of Ca(OH)2 along specific [hkl] directions, preserving the external hexagonal (platelike) morphology of the parent phase. Textural and kinetic results reveal that this pseudomorphic replacement involves a 3D diffusion-controlled deceleratory advancement of the reaction front. The results are consistent with an interface-coupled dissolution-precipitation replacement mechanism. Analysis of the carbonation of Ca(OH)2 particles with different degree of conversion into Ca-ethoxide (α up to 0.08) and Ca-isopropoxide (α up to 0.04) exposed to air (20 °C, 80% relative humidity) reveals that Ca-alkoxides significantly reduce the rate of transformation into cementing CaCO3 and induce the formation of metastable vaterite, as opposed to stable calcite which forms in untransformed Ca(OH)2 samples. Similar effects are obtained when a commercial nanolime partially transformed into Ca-ethoxide is subjected to carbonation. Such effects may hamper/delay the strengthening or consolidation effects of nanolimes, thus having

  5. Tetrabromidocuprates(II)-Synthesis, Structure and EPR.

    Science.gov (United States)

    Zabel, André; Winter, Alette; Kelling, Alexandra; Schilde, Uwe; Strauch, Peter

    2016-01-01

    Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several "onium" cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II) centres. For the majority of compounds, the principal g values (g‖ and g⊥) of the tensors could be determined and information on the structural changes in the [CuBr₄](2-) anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids. PMID:27104522

  6. Tetrabromidocuprates(II—Synthesis, Structure and EPR

    Directory of Open Access Journals (Sweden)

    André Zabel

    2016-04-01

    Full Text Available Metal-containing ionic liquids (ILs are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II with several “onium” cations in comparison to the results of electron paramagnetic resonance (EPR spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II centres. For the majority of compounds, the principal g values (g‖ and g⊥ of the tensors could be determined and information on the structural changes in the [CuBr4]2− anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids.

  7. Use of Modal Synthesis for Composite Structures

    Directory of Open Access Journals (Sweden)

    Musil Miloš

    2014-12-01

    Full Text Available A common occurrence in engineering practice is undesirable levels of vibration in the structures of machinery, which decrease their functionality, safety, reliability and service life. Current trends in the dynamic operation of machinery inherently generate such undesirable effects. That is to say, increasing the operational capacity of a machine (higher speeds, higher loads, more changes in operational regimes, etc... is financially counterproductive to any desired savings in the material/technological realization of such structures. One possible approach to modify the dynamic properties of the structure is through modal synthesis. This approach combines the modal properties of the real structure obtained through measurements with the modal properties of additional components obtained computationally. This approach is particularly effective if the computational model of the built structure is incorrect.

  8. Perspectives of applications of alkoxide sol-gel process in heterogeneous catalysis

    International Nuclear Information System (INIS)

    Basic principles, specific features, advantages and drawbacks of alkoxide technology application for the preparation of oxide heterogeneous catalysts and carriers (RuO, V2O5, ZrO2, B2O3) have been considered. Application of acetylacetonates E(acac)n is considered alongside with mixed alkoxyacetylacetonates E(OR)x(acac)n-1. The lack of extensive commercial production of Al and Zr alkoxides in Russia rather than their high cost, is a real obstacle for alkoxide technology introduction. 293 refs., 2 figs., 2 tabs

  9. Application of optimality criteria in structural synthesis

    Science.gov (United States)

    Terai, K.

    1974-01-01

    The rational use of optimality criteria was investigated for a class of structural synthesis problems where materials, configuration and applied load conditions are specified, and the minimum weight design is to be determined. The potential of hybrid methods of structural optimization for dealing with relatively large design problems involving practical complexity was explored. The reduced basis concept in design space was used to decrease the number of generalized design variables dealt with by the mathematical programming algorithm. Optimality criteria methods for obtaining design vectors associated with displacement, system buckling and natural frequency constraints are presented. A stress ratio method was used to generate a basis design vector representing the stress constraints. The finite element displacement method was used as the basic structural analysis tool. Results for several examples of truss systems subject to stress, displacement and minimum size constraints are presented. An assessment of these results indicates the effectiveness of the hybrid method developed.

  10. Negative Hyperconjugation versus Electronegativity: Vibrational Spectra of Free Fluorinated Alkoxide Ions in the Gas Phase

    NARCIS (Netherlands)

    J. Oomens; G. Berden; T.H. Morton

    2015-01-01

    CO stretching frequencies of free, gaseous, fluorinated alkoxide ions shift substantially to the blue, relative to those of corresponding alcohols complexed with ammonia. Free -fluorinated ions, pentafluoroethoxide and heptafluoroisopropoxide anions, display further blue shifts relative to cases wit

  11. Optical and electrical properties of vanadium oxide films deposited from alkoxides

    OpenAIRE

    Livaje, J.

    1998-01-01

    Vanadium oxide thi n films are formed via the hydrolysis and condensation of vanadium alkoxides. Sol-gel chemistry provides a chemical control over condensation reactions and different materials are actually obtained depending on experimental conditions. The hydrolysis of vanadium alkoxide in the presence of an excess of water leads to ribbon-like particles of hydrated oxide V205.nH20. Coatings with a preferred orientation are then deposited from these gels. They exhibit improved ele...

  12. The nature of the alkoxide group, solvent, catalyst, and concentration on the gelation and porosity of hexylene-bridged polysilsesquioxanes

    Energy Technology Data Exchange (ETDEWEB)

    Loy, D. A. (Douglas A.); Small, J. H. (James H.)

    2004-01-01

    Hexylene-bridged polysilsesquioxanes are hybrid organic-inorganic materials prepared by the sol-gel polymerization of 1,6-bis(trialkoxysilyl)hexane monomers: (1) R = Methyl; (2) R = Ethyl; and (3) R = n-Propyl. Previous studies showed that high surface area xerogels could be prepared from 2 with base catalyzed polymerizations while non-porous xerogels could be prepared with acidic catalysts. The object of this study was to ascertain the influences of monomer alkoxide group, solvent, catalyst, and monomer concentration on gelation time, and the properties of the resulting xerogels.This study has provided some insight into the chemical parameters that affect the ultimate structure in bridged polysilsesquioxanes. First, gelation times do not necessarily directly reflect the hydrolysis and condensation rates expected for different alkoxide groups. The collapse of porosity during the drying of hexylene-bridged polysilsesquioxanes occurs in nearly all acid-catalyzed samples, save those that form quickly due to concentration or from the methoxide monomer 1 in methanolic solution. This suggests that there may be a kinetic contribution to creating porosity in addition to the network compliance model. It would also appear that syneresis of gels during aging may be the symptom of changes resulting in increased porosity. Whatever these changes may be due to, they do not appear to significantly alter the structural composition. Experiments are underway to provide more information and test some of these hypotheses.

  13. Wall grid structure for interior scene synthesis

    KAUST Repository

    Xu, Wenzhuo

    2015-02-01

    We present a system for automatically synthesizing a diverse set of semantically valid, and well-arranged 3D interior scenes for a given empty room shape. Unlike existing work on layout synthesis, that typically knows potentially needed 3D models and optimizes their location through cost functions, our technique performs the retrieval and placement of 3D models by discovering the relationships between the room space and the models\\' categories. This is enabled by a new analytical structure, called Wall Grid Structure, which jointly considers the categories and locations of 3D models. Our technique greatly reduces the amount of user intervention and provides users with suggestions and inspirations. We demonstrate the applicability of our approach on three types of scenarios: conference rooms, living rooms and bedrooms.

  14. Some approximation concepts for structural synthesis

    Science.gov (United States)

    Schmit, L. A., Jr.; Farshi, B.

    1974-01-01

    An efficient automated minimum weight design procedure is presented which is applicable to sizing structural systems that can be idealized by truss, shear panel, and constant strain triangles. Static stress and displacement constraints under alternative loading conditions are considered. The optimization algorithm is an adaptation of the method of inscribed hyperspheres and high efficiency is achieved by using several approximation concepts including temporary deletion of noncritical constraints, design variable linking, and Taylor series expansions for response variables in terms of design variables. Optimum designs for several planar and space truss examples problems are presented. The results reported support the contention that the innovative use of approximation concepts in structural synthesis can produce significant improvements in efficiency.

  15. Synthesis and Crystal Structure of a Tetranuclear Cubane-like Nickel(Ⅱ) Complex with 2-Hydroxymethyl-N-salicylideneaniline

    Institute of Scientific and Technical Information of China (English)

    LIU, Hui-Yan; WANG, Hai-Ying; SHI, Da-Qing; TIAN, Jin-Lei

    2006-01-01

    The tetranuclear cubane-like complex, [NiL(EtOH)]4·0.5EtOH (1) with tridentate Schiff base ligand (H2L=2-Hydroxymethyl-N-salicylideneaniline) has been synthesized and its crystal structure and spectroscopic properties have been studied. The complex consists of a tetranuclear (NiO)4 cubane core, of which four nickel(Ⅱ) ions are bridged by μ3-alkoxide group and each nickel(Ⅱ) ion is coordinated to three ,u3-alkoxide oxygen atoms, one imino nitrogen atom and one phenoxide oxygen atom from Schiff base ligand, and further ligated by one EtOH molecule,completing a distorted octahedral geometry.

  16. Synthesis and structure characterization of diethyldiallylammonium chloride

    Institute of Scientific and Technical Information of China (English)

    刘立华; 龚竹青; 郑雅杰

    2003-01-01

    The unsaturated quaternary ammonium salt diethyldiallylammonium chloride(DEDAAC) was synthesized in a two-step synthetic method. The influences of the adding method of raw materials and temperature on the yields of diethylallylamine (DEAA), and drying and temperature on the synthesis of DEDAAC were investigated. The content of in-process product DEAA was determined by non-aqueous titration. The structure of product DEDAAC was identified with IR, 1 H NMR and elemental analysis. The results show that adding allyl chloride and sodium hydroxide alternately can increase the yield of DEAA and decrease by-products. In further synthesizing of DEDAAC from DEAA, the step of drying DEAA is very necessary. When DEAA is dried by solid sodium hydroxide, good columnar crystals with a high purity(mp 199.5-201.0 ℃) are obtained; when DEAA is undried or the content of water in DEAA is above 20%, only platelets with bad quality are obtained even without crystals. The suitable synthesis conditions for DEAA and DEDAAC are 35 ℃, 6 h and 40 ℃, 36 h, respectively, and their yields are 69.7% and 67.3%, respectively.

  17. Mullite Ceramics: Its Properties Structure and Synthesis

    Directory of Open Access Journals (Sweden)

    Juliana Anggono

    2005-01-01

    Full Text Available Besides its importance for conventional ceramics, mullite has become a choice of material for advanced structural and functional ceramics due to its favourable properties. Some outstanding properties of mullite are low thermal expansion, low thermal conductivity, excellent creep resistance, high-temperature strength, and good chemical stability. The mechanism of mullite formation depends upon the method of combining the alumina- and silica-containing reactants. It is also related to the temperature at which the reaction leads to the formation of mullite (mullitisation temperature. Mullitisation temperatures have been reported to differ by up to several hundred degrees Celsius depending on the synthesis method used. The three synthesis methods used to prepare mullite are discussed in this paper together with an overview of mullite, its properties and the current application of mullite. Abstract in Bahasa Indonesia : Keramik mullite tidak hanya penting dalam penggunaan konvensional, tetapi juga sudah menjadi bahan pilihan untuk aplikasi struktural dan fungsional karena sifat-sifatnya yang menguntungkan. Beberapa keunggulan sifat mullite adalah sifat muai dan konduktivitas panasnya rendah, ketahanan mulur yang tinggi, kekuatan yang terjaga pada temperatur tinggi, dan sifat korosinya yang baik. Mekanisme pembentukan mullite bergantung pada bagaimana proses menggabungkan reaktan yang mengandung alumina dan silika. Mekanisme tersebut juga bergantung pada temperatur reaksi awal yang akan mengarah pada pembentukan mullite (mullitisation. Beberapa penelitian melaporkan terjadinya temperatur mullitisation yang bervariasi hingga beberapa ratus derajat Celsius bergantung pada proses sintesa yang digunakan. Artikel ini menjelaskan tiga proses sintesa yang menghasilkan mullite yang dibahas bersama dengan sifat-sifat dan aplikasi mullite saat ini. Kata kunci: mullite, mullitisation, fasa glassy, sol-gel, spray pyrolysis, chemical vapour deposition.

  18. Synthesis and structures of cuprous triptycylthiolate complexes.

    Science.gov (United States)

    Ferrara, Skylar J; Mague, Joel T; Donahue, James P

    2012-06-18

    A synthesis of 1-(thioacetyl)triptycene (5), a convenient protected form of 1-(thiolato)triptycene [STrip](-), is described, a key transformation being the high yield conversion of tert-butyl 1-triptycenyl sulfide (8) to 5 by a protocol employing BBr(3)/AcCl. Syntheses of the two-coordinate copper(I) compounds [Bu(4)N][Cu(STrip)(2)], [Bu(4)N]10, and [(Cu(IMes)(STrip)] (13) proceed readily by chloride displacement from CuCl and [Cu(IMes)Cl], respectively. Reaction of 10 with Ph(3)SiSH or Me(3)SiI produces the heteroleptic species [Cu(STrip)(SSiPh(3))](-) (11) and [Cu(STrip)I](-) (12), detected by mass spectrometry, in mixture with the homoleptic bis(thiolate) anions. Structural identification by X-ray crystallography of the ligand precursor molecules 9-(thioacetyl)anthracene (4, triclinic and orthorhombic polymorphs), tert-butyl 9-anthracenyl sulfide (7), 5, and tert-butyl 1-triptycenyl sulfide (8) are presented. Crystallographic characterization of bis(9-anthracenyl)sulfide (3), which features a C-S-C angle of 104.0° and twist angle of 54.8° between anthracenyl planes, is also given. A crystal structure of [Bu(4)N][(STrip)], [Bu(4)N]9, provides an experimental measure of 144.6° for the ligand cone angle. The crystal structures of [Bu(4)N]10 and 13 are reported, the former of which reveals an unexpectedly small C-S···S-C torsion angle of ∼41° (average of two values), which confers a near "cis" disposition of the triptycenyl groups with respect the S-Cu-S axis. This conformation is governed by interligand π···π and CH···π interactions. A crystal structure of an adventitious product, [Bu(4)N][(Cu-STrip)(6)(μ(6)-Br)]·[Bu(4)N][PF(6)], [Bu(4)N]14·[Bu(4)N][PF(6)] is described, which reveals a cyclic hexameric structure previously unobserved in cuprous thiolate chemistry. The Cu(6)S(6) ring displays a centrosymmetric cyclohexane chair type conformation with a Br(-) ion residing at the inversion center and held in place by apparent soft

  19. Organoactinide chemistry: synthesis, structure, and solution dynamics

    International Nuclear Information System (INIS)

    This thesis considers three aspects of organoactinide chemistry. In chapter one, a bidentate phosphine ligand was used to kinetically stabilize complexes of the type Cp2MX2. Ligand redistribution processes are present throughout the synthetic work, as has often been observed in uranium cyclopentadienyl chemistry. The effects of covalent M-L bonding on the solution and solid state properties of U(III) coordination complexes are considered. In particular, the nature of the more subtle interaction between the metal and the neutral ligand are examined. Using relative basicity data obtained in solution, and solid state structural data (and supplemented by gas phase photoelectron measurements), it is demonstrated that the more electron rich U(III) centers engage in significant U → L π-donation. Trivalent uranium is shown to be capable of acting either as a one- or two-electron reducing agent toward a wide variety of unsaturated organic and inorganic molecules, generating molecular classes unobtainable via traditional synthetic approaches, as well as offering an alternative synthetic approach to molecules accessible via metathesis reactions. Ligand redistribution processes are again observed, but given the information concerning ligand lability, this reactivity pattern is applied to the synthesis of pure materials inaccessible from redox chemistry. 214 refs., 33 figs., 10 tabs

  20. Organoactinide chemistry: synthesis, structure, and solution dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Brennan, J.G.

    1985-12-01

    This thesis considers three aspects of organoactinide chemistry. In chapter one, a bidentate phosphine ligand was used to kinetically stabilize complexes of the type Cp/sub 2/MX/sub 2/. Ligand redistribution processes are present throughout the synthetic work, as has often been observed in uranium cyclopentadienyl chemistry. The effects of covalent M-L bonding on the solution and solid state properties of U(III) coordination complexes are considered. In particular, the nature of the more subtle interaction between the metal and the neutral ligand are examined. Using relative basicity data obtained in solution, and solid state structural data (and supplemented by gas phase photoelectron measurements), it is demonstrated that the more electron rich U(III) centers engage in significant U ..-->.. L ..pi..-donation. Trivalent uranium is shown to be capable of acting either as a one- or two-electron reducing agent toward a wide variety of unsaturated organic and inorganic molecules, generating molecular classes unobtainable via traditional synthetic approaches, as well as offering an alternative synthetic approach to molecules accessible via metathesis reactions. Ligand redistribution processes are again observed, but given the information concerning ligand lability, this reactivity pattern is applied to the synthesis of pure materials inaccessible from redox chemistry. 214 refs., 33 figs., 10 tabs.

  1. Decision support system for structure synthesis of monitoring systems

    Directory of Open Access Journals (Sweden)

    Skatkov A. V.

    2008-04-01

    Full Text Available The paper is concerned with a structure synthesis of monitoring systems. In the article a decision support system for such synthesis was proposed and described. In the first phase of the process, the proposed classification of monitoring systems is used. Then adaptive algorithms, simulation and analytic modeling are used. The results of studies carried out by means of the proposed program are represented. The topicality of proposed approach was demonstrated. It should be mentioned, that algorithms were thoroughly described, the computing experiments were carried out. The authors believe that the proposed decision support system has many advantages and, consequently, is very useful in structure synthesis of monitoring systems.

  2. Synthesis of aminopyrimidylindoles structurally related to meridianins

    OpenAIRE

    Rossignol, Emilie; Youssef, Ali; Moreau, Pascale; Prudhomme, Michelle; Anizon, Fabrice

    2007-01-01

    The synthesis of new meridianin derivatives substituted at the C-5′ position of the 2-aminopyrimidine ring by various aryl groups and substituted or not by a methyl group on the indole nitrogen is described. The 2-aminopyrimidine ring was obtained via a Bredereck synthesis. Aryl groups were introduced by Suzuki cross-coupling after bromination of the 2-aminopyrimidine ring at the C-5′ position

  3. Dynamic analysis of large structures by modal synthesis techniques.

    Science.gov (United States)

    Hurty, W. C.; Hart, G. C.; Collins, J. D.

    1971-01-01

    Several criteria that may be used to evaluate the merits of some of the existing techniques for the dynamic analysis of large structures which involve division into substructures or components are examined. These techniques make use of component displacement modes to synthetize global systems of generalized coordinates and, for that reason, they have come to be known as modal synthesis or component mode methods. Two techniques have been found to be particularly useful - i.e., the modal synthesis method with fixed attachment modes, and the modal synthesis method with free attachment modes. These two methods are treated in detail, and general flow charts are presented for guidance in computer programming.

  4. Decision support system for structure synthesis of monitoring systems

    OpenAIRE

    Skatkov A. V.; Voronin D. Y.; Danilchuk D. N.

    2008-01-01

    The paper is concerned with a structure synthesis of monitoring systems. In the article a decision support system for such synthesis was proposed and described. In the first phase of the process, the proposed classification of monitoring systems is used. Then adaptive algorithms, simulation and analytic modeling are used. The results of studies carried out by means of the proposed program are represented. The topicality of proposed approach was demonstrated. It should be mentioned, that algor...

  5. Green Process for Synthesis of Zeolite with MFI Structure

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A clean and environmentally friendly new process for synthesis of zeolite with MFI structure was presented. This process through recycling of vented gas and mother liquor can reduce or avoid discharge of nitrogen-containing offgas and waste liquid without affecting the physical and chemical properties of synthetic zeolite, leading to green synthesis of zeolite. This process can help to cut corners on production cost to achieve the sustainable development.

  6. Concise total synthesis and structural revision of (+)-pestalazine B.

    Science.gov (United States)

    Pérez-Balado, Carlos; de Lera, Angel R

    2010-11-21

    A convergent synthesis of the proposed structure of (+)-pestalazine B has been achieved in 4 steps using the N-alkylation of an unprotected tryptophan diketopiperazine with a 3a-bromopyrrolidinoindoline as the key step. Although its structure was confirmed by X-ray analysis, the spectroscopic data did not match those of the natural product. The versatility of the methodology allowed the preparation of several diastereomers, and the database generated led to the proposal of an isomeric structure for the natural alkaloid where the d-leucine and d-phenylalanine residues exchanged positions, which was corroborated by total synthesis. PMID:20848034

  7. Asymmetric catalytic synthesis of the proposed structure of trocheliophorolide B.

    Science.gov (United States)

    Trost, Barry M; Quintard, Adrien

    2012-09-01

    A concise catalytic asymmetric synthesis of the proposed structure of trocheliophorolide B is reported. The synthetic sequence notably features an asymmetric acetaldehyde alkynylation, a Ru-catalyzed alder-ene reaction, and a Zn-ProPhenol ynone aldol condensation. Comparison with the reported data suggests a misassignment of the natural product structure.

  8. Asymmetric catalytic synthesis of the proposed structure of trocheliophorolide B

    OpenAIRE

    Trost, Barry M.; Quintard, Adrien

    2012-01-01

    A concise catalytic asymmetric synthesis of the proposed structure of Trocheliophorolide B is reported. The synthetic sequence notably features an asymmetric acetaldehyde alkynylation, Ru-catalyzed alder-ene reaction and Zn-ProPhenol ynone aldol condensation. Comparison with the reported data suggests a miss-assignment of the natural product structure.

  9. Preparation of zirconia coatings by hydrolysis of zirconium alkoxide with hydrogen peroxide

    International Nuclear Information System (INIS)

    Zirconia has gained a great deal of attention because of its superior properties of mechanical strength, chemical resistance, and ionic conductivity. Zirconia coatings and thin films are receiving attention as tribological and thermal barrier coatings for engines, high-reflective coatings, solid electrolytes for fuel cells, oxygen sensors, etc. The sol-gel coating method has several advantages, such as low processing temperatures, homogeneity, control of micro-structure, and good productivity compared to chemical vapor deposition and physical vapor deposition. However, there are few reports concerning the preparation of zirconia coatings and thin films by the sol-gel method. Up to the present, zirconia coatings have been prepared from zirconium propoxide (not heated), zirconium tetrabutoxide modified by acetylacetone and ethyl acetoacetate, zirconium diethoxydichloride (ZrCl2(OC2H5)2), and a hydrosol prepared from a zirconium oxychloride solution. Coatings of 8.8-mol%-yttria-doped zirconia were fabricated using a transparent and spinnable sol prepared by hydrolysis of zirconium alkoxide with hydrogen peroxide and nitric acid. The sol gave a crack-free coating film consisting of fine grains. The crystalline phase was cubic after heating of 1,000 and 1,200 C and cubic and tetragonal at 1,350 C, with the coating being highly oriented in the (111) plane, especially at 1,000 C. Activation energy of the coating films was higher than that of the bulk. Transmittance through a film thickness of about 0.3 μm on each side was 75%

  10. Experimental component mode synthesis of structures with sloppy joints

    Science.gov (United States)

    Blackwood, Gary H.; Von Flotow, A. H.

    1988-01-01

    The accuracy of component mode synthesis is investigated experimentally for substructures coupled by nonideal joints. The work is based upon a segmented experimental beam for which free-interface frequency response matrices are measured for each segment. These measurements are used directly in component mode synthesis to predict the behavior of the assembled structure; the segments are then physically joined, and the resulting frequency response of the superstructure is compared to the prediction. Rotational freeplay is then introduced into the connecting joint, and the new superstructure frequency response is compared to the original linear component mode synthesis prediction. The level of accuracy to be expected in component mode synthesis is discussed in terms of the degree of nonlinearity in the joints, mode number, and mode shapes.

  11. An advanced structural analysis/synthesis capability - ACCESS 2

    Science.gov (United States)

    Schmit, L. A.; Miura, H.

    1978-01-01

    An advanced automated design procedure for minimum weight design of structures (ACCESS 2) is reported. Design variable linking, constraint deletion, and explicit constraint approximation are used to effectively combine finite element and nonlinear mathematical programming techniques. The approximation concepts approach to structural synthesis is extended to problems involving fiber composite structure, thermal effects and natural frequency constraints in addition to the usual static stress and displacement limitations. Sample results illustrating these new features are given.

  12. Structure-reactivity relationships in aluminium alkoxides-catalysed co-polymerisation reactions : aluminium 2,2' methylenebisphenoxide in the synthesis of poly(ether-carbonate)s from cyclohexene oxide and carbon dioxide

    OpenAIRE

    Sypien, Jakub Konrad

    2006-01-01

    Das Design und die Synthese von "Single-Site"-Katalysatoren für die Copolymerisierung von Kohlendioxids und Cyclohexenoxid (CHO), Untersuchungen zu ihrer Struktur-Reaktivitätsbeziehung sowie die Optimierung der Reaktionsparameter waren Hauptaugenmerk dieser Arbeit. Die Liganden für das Katalysator-Design beruhen auf 2,2'-Bisphenol-Derivaten, entweder Methylen- (1-6 basierte Systeme) oder Sulfid-verbrückt (7 basierte Systeme). Die meisten der verwendeten Liganden wurden bereits in der Literatu...

  13. POLYMETALLIC CHROMIUM ALKOXIDES - SYNTHESIS AND CRYSTAL-STRUCTURES OF (I-PRO)8CR2NA4(THF)4 AND (MU-3-OPH)10CR4(MU-3-O)3NA4(TMEDA)4

    NARCIS (Netherlands)

    EDEMA, JJH; GAMBAROTTA, S; SMEETS, WJJ; SPEK, AL

    1991-01-01

    The reaction of (RO)8Cr2Na4(THF)4[R = i-Pr (1a), Ph (1b)] with TMEDA (TMEDA = N,N,N',N'-tetramethylethylenediamine) has been studied. While the isopropyl derivative 1a yielded the polymeric [(i-PrO)2Cr]n, in the case of 1b, the Cr(III) aggregate (PhO)10Cr4(mu-3-O)3Na4(TMEDA)4 (2) was formed via an u

  14. Photoinduced Formation of Colloidal Silver in Nitrocellulose Solutions Containing Titanium Alkoxides

    Science.gov (United States)

    Kulak, A. I.; Branitsky, G. A.

    2016-07-01

    The study shows the possibility of photo-induced reduction of silver nitrate and formation of stable colloidal silver particles in an isopropanol-N,N-dimethylacetamide solution of titanium alkoxide (polybutyl titanate) stabilized by nitrocellulose. It is established that titanium alkoxide and the products of its partial hydrolysis in the liquid composition play the role of a photocatalyst for the reduction of silver ions; the introduction of nitric or acetic acid additives to the composition significantly increases its photosensitivity. The films deposited from the liquid composition, previously irradiated with visible or UV light, consist of hydrated titanium dioxide and nitrocellulose with incorporated colloidal silver. Thermal treatment of the films at 150-245°C leads to the decomposition of nitrocellulose and an increase in the absorption by silver particles.

  15. Hydrolytic activity of -alkoxide/acetato-bridged binuclear Cu(II) complexes towards carboxylic acid ester

    Indian Academy of Sciences (India)

    Weidong Jiang; Bin Xu; Zhen Xiang; Shengtian Huang; Fuan Liu; Ying Wang

    2013-09-01

    Two -alkoxide/acetate-bridged small molecule binuclear copper(II) complexes were synthesized, and used to promote the hydrolysis of a classic carboxylic acid ester, -nitrophenyl picolinate (PNPP). Both binuclear complexes exhibited good hydrolytic reactivity, giving rise to . 15547- and 17462-fold acceleration over background value for PNPP hydrolysis at neutral conditions, respectively. For comparing, activities of the other two mononuclear analogues were evaluated, revealing that binuclear complexes show approximately 150- and 171-fold kinetic advantage over their mononuclear analogues.

  16. Negative Hyperconjugation versus Electronegativity: Vibrational Spectra of Free Fluorinated Alkoxide Ions in the Gas Phase.

    Science.gov (United States)

    Oomens, Jos; Berden, Giel; Morton, Thomas Hellman

    2015-06-22

    CO stretching frequencies of free, gaseous, fluorinated alkoxide ions shift substantially to the blue, relative to those of corresponding alcohols complexed with ammonia. Free α-fluorinated ions, pentafluoroethoxide and heptafluoroisopropoxide anions, display further blue shifts relative to cases with only β-fluorination, providing experimental evidence for fluorine negative hyperconjugation. DFT analysis with the atoms in molecules (AIM) method confirms an increase in CO bond order for the α-fluorinated ions, demonstrating an increase in carbonyl character for the free ions.

  17. Synthesis and Crystal Structure of a New Salen Complex

    Institute of Scientific and Technical Information of China (English)

    LI Li-Jun; LI Ying; SUN Wen-Hua

    2003-01-01

    @@ Salen Schiff base complexes are some of the most important stereochemical models in transition metal coordina tion chemistry, with their ease of preparation and structural variation. [1] Salen complexes are extensively used as organic reaction catalysts, it was reported to be used in asymmetric cyclopropanation, epoxidation, aziridination, hydrolysis, alkylation, Diels-Alder reaction, reduction, oxidation etc. Here we report the synthesis and structure of a new salen nickel complex 4.

  18. Homochiral metal complexes for biodegradable polymer synthesis

    OpenAIRE

    Buffet, Jean-Charles

    2010-01-01

    Chapter One introduces the principle of alkoxide and phosphine oxide as ligands for lanthanides and electropositive metals, ligand self-recognition, stereoselective polymerisation of lactide, fixation of CO2 and finally copolymerisation of CO2 and epoxide. Chapter Two shows the synthesis of the proligands rac-HLR (a racemic phosphine oxide-alkoxide, A, where R = tBu, Ph or C6H3-Me-3,5) and explores the resolution into diastereomeric RRR- and SSS-M(LR)3 to afford C3–symmetric...

  19. Synthesis and Crystal Structure of a New Manganese Complex

    Institute of Scientific and Technical Information of China (English)

    WANG Jian; LIU Ping; CHEN Yun

    2003-01-01

    @@ In order to study the relationship between the manganese ion and the biological coordination agent, the role ofmanganese ion in the active sites and the structure of the active sites in the manganese enzymes, small molecule complexes are often applied to modeling the structure and the properties of reaction in the active centers. In this pa per, we will report the synthesis and crystal structure of a new manganese(Ⅱ) complex, catena[ aqua-(p-methoxybenzoato- O, O′ ) - (p-methoxybenzoato- O )- (2,2′-bipyridine)-manganese (Ⅱ) ] (p-methoxybenzoic acid). The crystal structure was confirmeded by X-ray crystallography analysis.

  20. SYNTHESIS OF PLASTIC PIGMENT WITH MULTIHOLLOW STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    LiqiangJin; QinghuaXu; ZonglinLiu

    2004-01-01

    The polymer particle possessing hollow structure are playing an increasingly important role in industry. The latex particle with hollow structure as plastic pigment has a low density, strong spreading capacity and good glossiness. So it has been utilized for the manufacture of LWC in paper-making. In this paper, we prepared a kind of novel plastic pigment by the soapless seeded emulsion polymerization, this product with polyacrylate as core and with polystyrene as shell (PA/PS) had hollow structure after dryness. The preparation, characterization and properties of the latex were studied in detail by chemistry analysis and apparatus analysis such as TEM,FTIR,DLS.

  1. SYNTHESIS OF PLASTIC PIGMENT WITH MULTIHOLLOW STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    Liqiang Jin; Qinghua Xu; Zonglin Liu

    2004-01-01

    The polymer particle possessing hollow structure are playing an increasingly important role in industry.The latex particle with hollow structure as plastic pigment has a low density, strong spreading capacity and good glossiness. So it has been utilized for the manufacture of LWC in paper-making. In this paper,we prepared a kind of novel plastic pigment by the soapless seeded emulsion polymerization, this product with polyacrylate as core and with polystyrene as shell (PA/PS) had hollow structure after dryness. The preparation, characterization and properties of the latex were studied in detail by chemistry analysis and apparatus analysis such as TEM,FTIR,DLS.

  2. Facile chemical synthesis and structure characterization of copper molybdate nanoparticles

    Science.gov (United States)

    Rahimi-Nasrabadi, Mehdi; Pourmortazavi, Seied Mahdi; Khalilian-Shalamzari, Morteza

    2015-03-01

    Experimental parameters of a synthesis route were optimized by Taguchi robust design for the facile and controllable synthesis of copper molybdate nanoparticles. CuMoO4 nanoparticles were synthesized by chemical precipitation followed by hydrothermal process. Effects of different parameters of synthesis procedure, i.e. concentrations of both reagents, copper feeding flow rate and temperature of reactor on the particle size of prepared copper molybdate nanoparticles were investigated. The results of statistical optimization revealed that the size of copper molybdate particles is dependent on the procedure variables involving copper concentrations, flow rate and temperature of the reactor; while, molybdate concentration has a no considerable role in determining the size of CuMoO4 particles. Based on the results obtained by statistical optimization process, the nanoparticles of copper molybdate were prepared and then their structure and chemical composition were characterized by various techniques, i.e. SEM, TEM, XRD, EDX, FT-IR, UV-Vis and photoluminescence spectroscopy.

  3. Characterization of amorphous yttria layers deposited by aqueous solutions of Y-chelate alkoxides complex

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young-Soon, E-mail: kyscjb@i-sunam.com; Lee, Yu-Ri; Kim, Byeong-Joo; Lee, Jae-Hun; Moon, Seung-Hyun; Lee, Hunju

    2015-01-15

    Highlights: • Economical method for crack-free amorphous yttria layer deposition by dip coating. • Simpler process for planar yttria film as a diffusion barrier and nucleation layer. • Easy control over the film properties with better characteristics. • Easy control over the thickness of the deposited films. • A feasible process that can be easily adopted by HTSCC industries. - Abstract: Crack-free amorphous yttria layers were deposited by dip coating in solutions of different Y-chelate alkoxides complex. Three Y-chelate solutions of different concentrations were prepared using yttrium acetate tetrahydrate, yttrium stearic acid as Y source materials. PEG, diethanolamine were used as chelating agents, while ethanol, methanol and tetradecane were used as solvent. Three different combinations of chelating and solvents were used to prepare solutions for Y{sub 2}O{sub 3} dip coating on SUS, electropolished and non-electropolished Hastelloy C-276 substrates. The thickness of the films was varied by changing the number of dipping cycles. At an optimized condition, the substrate surface roughness (rms) value was reduced from ∼50 nm to ∼1 nm over a 10 × 10 μm{sup 2} area. After Y{sub 2}O{sub 3} deposition, MgO was deposited using ion-beam assisted deposition (IBAD), then LaMnO{sub 3} (LMO) was deposited using sputtering and GdBCO was deposited using reactive co-evaporation by deposition and reaction (RCE-DR). Detailed X-ray study indicates that LMO/MgO/Y{sub 2}O{sub 3} and GdBCO/LMO/MgO/Y{sub 2}O{sub 3} stack films have good out-of-plane and in-plane textures with strong c-axis alignment. The critical current (Ic) of GdBCO/LMO/MgO/Y{sub 2}O{sub 3} multilayer structure varied from 190 to 420 A/cm with different solutions, when measured at 77 K. These results demonstrated that amorphous yttria can be easily deposited by dip coating using Y-chelates complex as a diffusion barrier and nucleation layer.

  4. Block-Krylov component synthesis method for structural model reduction

    Science.gov (United States)

    Craig, Roy R., Jr.; Hale, Arthur L.

    1988-01-01

    A new analytical method is presented for generating component shape vectors, or Ritz vectors, for use in component synthesis. Based on the concept of a block-Krylov subspace, easily derived recurrence relations generate blocks of Ritz vectors for each component. The subspace spanned by the Ritz vectors is called a block-Krylov subspace. The synthesis uses the new Ritz vectors rather than component normal modes to reduce the order of large, finite-element component models. An advantage of the Ritz vectors is that they involve significantly less computation than component normal modes. Both 'free-interface' and 'fixed-interface' component models are derived. They yield block-Krylov formulations paralleling the concepts of free-interface and fixed-interface component modal synthesis. Additionally, block-Krylov reduced-order component models are shown to have special disturbability/observability properties. Consequently, the method is attractive in active structural control applications, such as large space structures. The new fixed-interface methodology is demonstrated by a numerical example. The accuracy is found to be comparable to that of fixed-interface component modal synthesis.

  5. Use of Modal Synthesis for Composite Structures

    OpenAIRE

    Musil Miloš; Chlebo Ondrej

    2014-01-01

    A common occurrence in engineering practice is undesirable levels of vibration in the structures of machinery, which decrease their functionality, safety, reliability and service life. Current trends in the dynamic operation of machinery inherently generate such undesirable effects. That is to say, increasing the operational capacity of a machine (higher speeds, higher loads, more changes in operational regimes, etc...) is financially counterproductive to any desired savings in the material/t...

  6. Analysis of nonlinear structures via mode synthesis

    Science.gov (United States)

    Gieseke, R. K.

    1975-01-01

    An effective procedure for NASTRAN was developed that permits any number of substructures of any size to be synthesized for the purpose of developing normal modes of vibration of the complete structural system. The technique is extended to permit modal transient analysis of the subdivided system. This latter procedure permits the use of NASTRAN's ability to include nonlinear forces in the problem. The five-phase process is accomplished using standard NASTRAN rigid formats with problem-independent alter packages and DMAP sequences.

  7. Synthesis and structure of vanillin azomethines

    OpenAIRE

    Jasmina M. Jovanović; SANDRA S. KONSTANTINOVIĆ; Budimir V. Konstantinović

    2009-01-01

    Vanillin is most prominent as the principal flavor and aroma compound in vanilla. Vanillin has been used as a chemical intermediate in the production of pharmaceuticals and other fine chemicals.The two intermediates, assigned as intermediates I and II, were prepared by using vanillin and 1-butylbromide or 2-chloroacetic acid, respectively. The condensation of intermediates with 2,3- -diaminopyridine gave azomethines. Their structure was established by using elemental microanalysis, as well as...

  8. Sciduction: Combining Induction, Deduction, and Structure for Verification and Synthesis

    CERN Document Server

    Seshia, Sanjit A

    2012-01-01

    Even with impressive advances in automated formal methods, certain problems in system verification and synthesis remain challenging. Examples include the verification of quantitative properties of software involving constraints on timing and energy consumption, and the automatic synthesis of systems from specifications. The major challenges include environment modeling, incompleteness in specifications, and the complexity of underlying decision problems. This position paper proposes sciduction, an approach to tackle these challenges by integrating inductive inference, deductive reasoning, and structure hypotheses. Deductive reasoning, which leads from general rules or concepts to conclusions about specific problem instances, includes techniques such as logical inference and constraint solving. Inductive inference, which generalizes from specific instances to yield a concept, includes algorithmic learning from examples. Structure hypotheses are used to define the class of artifacts, such as invariants or progr...

  9. Polyureas from diamines and carbon dioxide: synthesis, structures and properties.

    Science.gov (United States)

    Wu, Chaoyong; Wang, Jinyao; Chang, Pingjing; Cheng, Haiyang; Yu, Yancun; Wu, Zhijian; Dong, Dewen; Zhao, Fengyu

    2012-01-14

    Polyureas were synthesized from diamines and carbon dioxide in the absence of any catalyst or solvent, analogous to the synthesis of urea from condensation of ammonia with carbon dioxide. The method used carbon dioxide as a carbonyl source to substitute highly toxic isocyanates for the synthesis of polyureas. FTIR and DFT calculations confirmed that strong bidentate hydrogen bonds were formed between urea motifs, and XRD patterns showed that the PUas were highly crystalline and formed a network structure through hydrogen bonds, which served as physical cross-links. The long chain PUas presented a microphase separated morphology as characterized by SAXS and showed a high melting temperature above 200 °C. The PUas showed high resistance to solvents and excellent thermal stability, which benefitted from their special network structures. The PUas synthesized by this method are a new kind of functional material and could serve some areas where their analogues with similar functional groups could not be applied. PMID:22120724

  10. Synthesis and structure of vanillin azomethines

    Directory of Open Access Journals (Sweden)

    Jasmina M. Jovanović

    2009-10-01

    Full Text Available Vanillin is most prominent as the principal flavor and aroma compound in vanilla. Vanillin has been used as a chemical intermediate in the production of pharmaceuticals and other fine chemicals.The two intermediates, assigned as intermediates I and II, were prepared by using vanillin and 1-butylbromide or 2-chloroacetic acid, respectively. The condensation of intermediates with 2,3- -diaminopyridine gave azomethines. Their structure was established by using elemental microanalysis, as well as UV/Vis, FTIR and 1H-NMR spectra. Synthesized compounds were tested for their antifungal activity against Candida albicans, Candida lipolytica and Sacharomyces cerevisiae.

  11. EXAFS and FTIR studies of selenite and selenate sorption by alkoxide-free sol–gel generated Mg–Al–CO 3 layered double hydroxide with very labile interlayer anions

    KAUST Repository

    Chubar, Natalia

    2014-08-08

    © the Partner Organisations 2014. Current research on Layered Double Hydroxides (LDHs, also known as hydrotalcites, HTs) is predominantly focused on their intercalations, but the industrial application of LDHs for anion exchange adsorption has not yet been achieved. It was recently recognized that, to develop LDH applications, these materials should be produced using methods other than direct co-precipitation. Mg-Al-CO3LDH produced using an alkoxide-free sol-gel synthesis showed exceptional removal properties for aqueous selenium species. Se K-edge EXAFS/XANES and FTIR studies (supporting the data by XRD patterns) were performed to explain the unusual adsorptive performance of Mg-Al LDH by revealing the molecular-level mechanism of HSeO3 -, SeO4 2-and {HSeO3 -+ SeO4 2-} uptake at pH 5, 7 and 8.5. The role of inner-sphere complexation (exhibited by inorganic adsorbents with good performance) in adsorption of both selenium aqueous species was not confirmed. However, Mg-Al LDH fully met the other expectations regarding the involvement of the interlayer anions. The interlayer carbonate (due to its favorable speciation and generous HT hydration) gave a "second breath" to selenite sorption and was the only mechanism that controlled the removal of Se(vi). Because inner sphere complexation was the leading mechanism for selenite removal, ion exchange via surface OH-and interlayer CO3 2-species was the only mechanism for selenate removal; both of these species were easily bound to Mg-Al LDH (on its surface and gently parked into the interlayer forming a multilayer without violation of the structure of Mg-Al-CO3LDH). This work provides the first theoretical explanation of why it is more difficult to sorb selenate than selenite and which material should be used for this purpose. This journal is

  12. Synthesis, structure and physicochemical properties of rutherfordite and tetrasodiumuranyltricarbonate

    International Nuclear Information System (INIS)

    Optimal methods of UO2CO3 and Na4[UO2(CO3)3] synthesis are developed. By the methods of x-ray diffraction, precision IR spectroscopy and thermography structure of these compounds and the process of their thermal decomposition are studied. Standard formation enthalpy at 298.15 K of crystalline Na4[UO2(CO3)3] (-4010±8.0 kJ/mol) are determined by the reaction calorimetry method

  13. A mixed inventory structure for German concatenative synthesis

    OpenAIRE

    Portele, Thomas; Höfer, Florian; Hess, Wolfgang

    1996-01-01

    In speech synthesis by unit concatenation a major point is the definition of the unit inventory. Diphone or demisyllable inventories are widely used but both unit types have their drawbacks. This paper describes a mixed inventory structure which is syllable oriented but does not demand a definite decision about the position of a syllable boundary. In the definition process of the inventory the results of a comprehensive investigation of coarticulatory phenomena at syllable boundaries were use...

  14. Tetrabromidocuprates(II)—Synthesis, Structure and EPR

    Science.gov (United States)

    Zabel, André; Winter, Alette; Kelling, Alexandra; Schilde, Uwe; Strauch, Peter

    2016-01-01

    Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several “onium” cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II) centres. For the majority of compounds, the principal g values (g‖ and g⊥) of the tensors could be determined and information on the structural changes in the [CuBr4]2− anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids. PMID:27104522

  15. Synthesis, structure, and properties of azatriangulenium salts

    DEFF Research Database (Denmark)

    Laursen, B.W.; Krebs, Frederik C

    2001-01-01

    A general synthetic route to novel nitrogen-bridged heterocyclic carbenium ions of the acridinium and triangulenium type has been developed and investigated. The synthetic method is based on nucleophilic aromatic substitution (SNAr) on the tris(2,6-dimethoxyphenyl)carbenium ion (1) with primary a...... amines and, by virtue of its stepwise and irreversible nature, provides a powerful tool for the preparation of a wide variety of new heterocyclic carbenium salts. Several derivatives of the three new oxygen- and/or nitrogen-bridged triangulenium salts, azadioxa- (6), diazaoxa- (7......), and triazatriangulenium (4), have been synthesized and their physicochemical properties have been investigated. Crystal structures for compounds 2 b-PF6: 2d-PF6, 4b-BF4, 4c-BF4, 6e-BF4, and 8 are reported. The different packing modes found for the triazatriagulenium salts are discussed in relation to the electrostatic...

  16. Quantifying the Sigma and Pi interactions between U(V) f orbitals and halide, alkyl, alkoxide, amide and ketimide ligands

    Energy Technology Data Exchange (ETDEWEB)

    University of California, Berkeley; Lukens, Wayne W.; Edelstein, Norman M.; Magnani, Nicola; Hayton, Trevor W.; Fortier, Skye; Seaman, Lani A.

    2013-06-20

    f Orbital bonding in actinide and lanthanide complexes is critical to their behavior in a variety of areas from separations to magnetic properties. Octahedral f1 hexahalide complexes have been extensively used to study f orbital bonding due to their simple electronic structure and extensive spectroscopic characterization. The recent expansion of this family to include alkyl, alkoxide, amide, and ketimide ligands presents the opportunity to extend this study to a wider variety of ligands. To better understand f orbital bonding in these complexes, the existing molecular orbital (MO) model was refined to include the effect of covalency on spin orbit coupling in addition to its effect on orbital angular momentum (orbital reduction). The new MO model as well as the existing MO model and the crystal field (CF) model were applied to the octahedral f1 complexes to determine the covalency and strengths of the ? and ? bonds formed by the f orbitals. When covalency is significant, MO models more precisely determined the strengths of the bonds derived from the f orbitals; however, when covalency was small, the CF model was better than either MO model. The covalency determined using the new MO model is in better agreement with both experiment and theory than that predicted by the existing MO model. The results emphasize the role played by the orbital energy in determining the strength and covalency of bonds formed by the f orbitals.

  17. Synthesis and Structure Elucidation of Celangulin Derivatives

    Institute of Scientific and Technical Information of China (English)

    ZHANG,Ji-Wen; WU,Wen-Jun; TIAN,Xuan

    2004-01-01

    @@ Celangulins are sesquiterpene polyol esters based on a core structure known as β-dihydroagarofuran from Celastrus angulatus Max. Some of them are environment acceptable-pesticides. In order to find new active compounds and study their SAR, sesquiterpene polyol esters libraries were synthesized based on the basic hydrolysis of the extract of the root bark of Celastrus angulatus which could offer the β-dihydroagarofuran polyol by combinatorial chemical method and the compounds with insecticidal activity were isolated by bioassay-guided fractionation. Two new compounds with insecticidal activity against Mythimna separata, were isolated and elucidated as 2β,6α,8β, 13-tetraisobutanoyloxy-1β,4,9α-trihydroxy-β-dihydroagarofuran (A) and 1β,2β,6α,8β, 13-pentaisobutanoyloxy-4α,9α-dihydroxy-β-dihydroagarofuran (B) mainly by 1H NMR, 13C NMRH-HCOSY, HMQC, HMBC and HRMS spectral data. A: [α]20D -7.3 (c 0.12, CHCl3), B: [α]20D -34.6 (c 0.8,CHCl3).

  18. Synthesis and Crystal Structure of Tetraimidzolium Dinicotinatooctamolybdate

    Institute of Scientific and Technical Information of China (English)

    KANGJie; ZHANGQuan-Zheng; 等

    2003-01-01

    The title compound,[C3H5N2]4(C6H5NO2)2(Mo8O26)]1,was synthesized by the reaction of H2MoO4,nicotinic acid and imidazole in aqueous solution,Single-crystal X-ray analysis has revealed that compound 1 (C24H30Mo8N10O30) crystallizes in the monoclinic system,space group P21/n,Mr=1706,10,a=12.529(1),b=12.796(1),c=14.038(1)°↑A,β=100.2(1)°,V=2215.3(2)°↑A3,Z=2,Dc=2.558 g/cm3,F(000)=1640,μ=2.299mm-1,the final R=0.0527 and wR=0.0964 for 3064 observed reflections with I>2σ(I),X-ray crystal structure analysis suggests that compound 1 consists of centrosymmetric dinicotinatooctamolybdate anion and four protonated imidazole cations ,which are linked into a three-dimensional frmawork through hydrogen bonding.

  19. Topology structure synthesis and analysis of spatial pyramid deployable truss structures for satellite SAR antenna

    Science.gov (United States)

    Wang, Yan; Deng, Zongquan; Liu, Rongqiang; Yang, Hui; Guo, Hongwei

    2014-07-01

    Many attentions for structural synthesis are paid to planar linkages and parallel mechanisms, while design novel pyramid deployable truss structure(PDTS) of satellite SAR mainly depends on experience of designer. To design novel configuration of PDTS, a two-step topology structure synthesis and analysis approach is proposed. Firstly, a conceptual configuration of PDTS is synthesized. Weighted graph and weighted adjacency matrix are established to realize topological description for PDTS. Graph properties are then summarized to distinguish differentia between PDTS and other type structures. According to graph properties, a procedure for synthesis conceptual configuration of PDTS is presented. Secondly, join relationship of components in a PDTS is analyzed. Kinematic chain and corresponding incidence/adjacency matrix are employed to analyze join relationship of PDTS. Properties and simplified rules of kinematic chain are extracted to construct kinematic chain. A procedure for construction kinematic chain of PDTS is then established. Finally, with this two-step approach all 11 rectangular pyramid deployable structures whose folded state is planar are discovered and their kinematic chains are constructed. Based on synthesis results, a novel deployable support structure for satellite SAR is designed. The proposed research can be applied to obtain some novel PDTSs, which is of great importance to design some novel deployable support structures for satellite SAR antenna.

  20. Structure prediction and targeted synthesis: a new Na(n)N2 diazenide crystalline structure.

    Science.gov (United States)

    Zhang, Xiuwen; Zunger, Alex; Trimarchi, Giancarlo

    2010-11-21

    Significant progress in theoretical and computational techniques for predicting stable crystal structures has recently begun to stimulate targeted synthesis of such predicted structures. Using a global space-group optimization (GSGO) approach that locates ground-state structures and stable stoichiometries from first-principles energy functionals by objectively starting from randomly selected lattice vectors and random atomic positions, we predict the first alkali diazenide compound Na(n)N(2), manifesting homopolar N-N bonds. The previously predicted Na(3)N structure manifests only heteropolar Na-N bonds and has positive formation enthalpy. It was calculated based on local Hartree-Fock relaxation of a fixed-structure type (Li(3)P-type) found by searching an electrostatic point-ion model. Synthesis attempts of this positive ΔH compound using activated nitrogen yielded another structure (anti-ReO(3)-type). The currently predicted (negative formation enthalpy) diazenide Na(2)N(2) completes the series of previously known BaN(2) and SrN(2) diazenides where the metal sublattice transfers charge into the empty N(2) Π(g) orbital. This points to a new class of alkali nitrides with fundamentally different bonding, i.e., homopolar rather than heteropolar bonds and, at the same time, illustrates some of the crucial subtleties and pitfalls involved in structure predictions versus planned synthesis. Attempts at synthesis of the stable Na(2)N(2) predicted here will be interesting.

  1. Synthesis of aircraft structures using integrated design and analysis methods

    Science.gov (United States)

    Sobieszczanski-Sobieski, J.; Goetz, R. C.

    1978-01-01

    A systematic research is reported to develop and validate methods for structural sizing of an airframe designed with the use of composite materials and active controls. This research program includes procedures for computing aeroelastic loads, static and dynamic aeroelasticity, analysis and synthesis of active controls, and optimization techniques. Development of the methods is concerned with the most effective ways of integrating and sequencing the procedures in order to generate structural sizing and the associated active control system, which is optimal with respect to a given merit function constrained by strength and aeroelasticity requirements.

  2. Application of component mode synthesis in structural dynamics

    Science.gov (United States)

    Craig, R. R.

    1986-01-01

    The principal analytical techniques used for component mode synthesis (CMS) of undamped systems and their application to structural dynamics are discussed. In the CMS, a system is divided into components or substructures, and for each of these components, the number of degrees of freedom is reduced by expressing the physical coordinates in terms of a reduced set of component modal coordinates. Among a number of component modes, a new form of component mode, called an applied force attachment mode, is described. Consideration is given to literature studies of damped structures and recent combined analytical/experimental studies.

  3. Optimal placement of active elements in control augmented structural synthesis

    Science.gov (United States)

    Sepulveda, A. E.; Jin, I. M.; Schmit, L. A., Jr.

    1992-01-01

    A methodology for structural/control synthesis is presented in which the optimal location of active members is treated in terms of (0,1) variables. Structural member sizes, control gains and (0,1) placement variables are treated simultaneously as design variables. Optimization is carried out by generating and solving a sequence of explicit approximate problems using a branch and bound strategy. Intermediate design variable and intermediate response quantity concepts are used to enhance the quality of the approximate design problems. Numerical results for example problems are presented to illustrate the efficacy of the design procedure set forth.

  4. Fast microwave treatments of single source alkoxides for nanostructured Li-ion battery electrodes.

    Science.gov (United States)

    Laveda, Josefa Vidal; Chandhok, Vibhuti; Murray, Claire A; Paterson, Gary W; Corr, Serena A

    2016-07-12

    Microwave or ultrasonic treatment of metal alkoxides presents a fast, low cost route to both anode and cathode nanomaterials for Li-ion battery applications. Here, we demonstrate the formation of LiMPO4 (M = Fe, Mn) and Mn3O4 nanostructures via this simple route which exhibit excellent electrochemical performances. This approach opens up a new avenue for the targeted design of nanostructured materials, where co-location of the desired metals in a single starting material shortens reaction times and temperatures since there is a decrease in diffusional energy requirements usually needed for these reactions to proceed. PMID:26486274

  5. Janus-Cube Octasilsesquioxane: Facile Synthesis and Structure Elucidation.

    Science.gov (United States)

    Oguri, Naoki; Egawa, Yasunobu; Takeda, Nobuhiro; Unno, Masafumi

    2016-08-01

    A perfect "Janus-cube" octasilsesquioxane, a nanometer-scale Janus particle with two different types of substituents, was synthesized through the cross-coupling of a "half-cube" cyclic sodium siloxanolate with another half-cube cyclic fluorosiloxane. The structure was confirmed by X-ray crystallography to be a Janus cube. The overall synthesis is simple and does not require drastic separation methods compared with previous methods. The synthesis of the Janus cube demonstrates a novel siloxane bond-forming reaction involving the coupling a silanol salt and fluorosilane. The reaction is mild, does not result in acid generation, and could be applied to the construction of other novel siloxane compounds. PMID:27225052

  6. Production of dispersed nanometer sized YAG powders from alkoxide, nitrate and chloride precursors and spark plasma sintering to transparency

    Energy Technology Data Exchange (ETDEWEB)

    Suarez, M., E-mail: m.suarez@cinn.e [Departamento de Materiales Nanoestructurados, Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Principado de Asturias - Consejo superior de Investigaciones Cientificas (CSIC) - Universidad de Oviedo - UO, Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain); Fernandez, A. [Fundacion ITMA, Parque Tecnologico de Asturias, 33428, Llanera (Spain); Menendez, J.L.; Torrecillas, R. [Departamento de Materiales Nanoestructurados, Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN), Principado de Asturias - Consejo superior de Investigaciones Cientificas (CSIC) - Universidad de Oviedo - UO, Parque Tecnologico de Asturias, 33428 Llanera, Asturias (Spain)

    2010-03-18

    Yttrium aluminum garnet (YAG) was synthesized from different starting materials, i.e., alkoxide, nitrate and chloride precursors. The conversion steps from the precursors to crystalline YAG were studied by Raman spectroscopy. Dispersed YAG powders were formed at a relatively low temperature, around 800 {sup o}C by the chlorides route, whereas alkoxide precursors needed firing over 900 {sup o}C and nitrates even over 1100 {sup o}C. Lyophilized YAG gel was sintered to transparency by the spark plasma sintering method at 1500 {sup o}C with in-line transmittances close to 60% at 680 nm and over 80% in the infrared range.

  7. Production of dispersed nanometer sized YAG powders from alkoxide, nitrate and chloride precursors and spark plasma sintering to transparency

    International Nuclear Information System (INIS)

    Yttrium aluminum garnet (YAG) was synthesized from different starting materials, i.e., alkoxide, nitrate and chloride precursors. The conversion steps from the precursors to crystalline YAG were studied by Raman spectroscopy. Dispersed YAG powders were formed at a relatively low temperature, around 800 oC by the chlorides route, whereas alkoxide precursors needed firing over 900 oC and nitrates even over 1100 oC. Lyophilized YAG gel was sintered to transparency by the spark plasma sintering method at 1500 oC with in-line transmittances close to 60% at 680 nm and over 80% in the infrared range.

  8. Synthesis of carbon nano structures by plasma discharge

    International Nuclear Information System (INIS)

    Due to the great quantity of applications of carbon neocarcinostatin (NEC) in diverse areas like: synthesis of super-resistant materials, hydrogen storage, nano sensors generation and nano catalysts, one has seen the necessity to generate new synthesis processes of these materials as well as to already improve those existent. The present work has as objective to optimize the NEC synthesis process by means of the electric arc method which uses alternating current to high frequencies (HF), obtaining relatively clean products; that is to say, it hardly presents amorphous material neither impurities. They stand out the obtaining of carbon nano fibers (NFC) by means of a luminescent-arc discharge, in a gas mixture He-CH4 with 34% at.Ni/10.32%at.Y like catalyst; to a frequency of 42 k Hz and low power (300 W). This method benefits the agglomeration of the particles in both electrodes due to the high frequencies. The time of duration of the process oscillates between 5 and 20 minutes. The obtained product was characterized by scanning electron microscopy (MEB), transmission electron microscopy (MET) to determine the type of obtained NEC and by X-ray diffraction analysis and Raman spectroscopy to determine the purity of the samples. The NFC are relatively free of amorphous coal. The surface and structural analysis indicates that the fibers have a half diameter of 80 nm. It is also made, a study by optical emission spectroscopy of the plasma using the Swan band to determine the temperature. (Author)

  9. Structure-based synthesis from natural products to drug prototypes

    International Nuclear Information System (INIS)

    X-Ray crystallographic data available from complexes of natural and synthetic molecules with the enzyme thrombin has aided to the design and synthesis of truncated and hybrid molecules exhibiting excellent inhibition in vitro. The vital importance of natural products for the well-being of man has been known lor millennia. Their therapeutic benefits to alleviate pain or cure diseases continue to rank natural products among the primary sources of potential drugs. Great advances have been made in the methods of isolation, identification, and structure elucidation of some of the most complex natural products in recent years. The advent of molecular biology and genetic mapping has also aided in our understanding of the intriguing biosynthetic pathways leading to various classes of therapeutically relevant antibiotic, anticancer, and related natural products. Elegant and practical methodology has been developed leading to the total synthesis of virtually every class of medicinally important natural product. In some cases, natural products or their chemically modified congeners have been manufactured by total synthesis on an industrial level which is a testament to the ingenuity of process chemists. In spite of their potent activities HI enzymatic ox receptor-mediated assays, not all natural products are amenable to being developed as marketable drags. In many instances unfavorable pharmacological effects cannot be overcome without drastic structural and functional modifications, which may also result in altered efficacy. Structure modification through truncation, functional group variations, isosteric replacements, and skeletal rigidifications aided by molecular modeling, X ray crystallography of protein targets, or NMR data are valid objectives in the context of small molecule drug discovery starting with bioactive natural products. A large proportion of these pertain to chemotherapeutic agents against cancer

  10. Global sensitivity analysis in control-augmented structural synthesis

    Science.gov (United States)

    Bloebaum, Christina L.

    1989-01-01

    In this paper, an integrated approach to structural/control design is proposed in which variables in both the passive (structural) and active (control) disciplines of an optimization process are changed simultaneously. The global sensitivity equation (GSE) method of Sobieszczanski-Sobieski (1988) is used to obtain the behavior sensitivity derivatives necessary for the linear approximations used in the parallel multidisciplinary synthesis problem. The GSE allows for the decoupling of large systems into smaller subsystems and thus makes it possible to determine the local sensitivities of each subsystem's outputs to its inputs and parameters. The advantages in using the GSE method are demonstrated using a finite-element representation of a truss structure equipped with active lateral displacement controllers, which is undergoing forced vibration.

  11. A General Chemistry Experiment Incorporating Synthesis and Structural Determination

    Science.gov (United States)

    van Ryswyk, Hal

    1997-07-01

    An experiment for the general chemistry laboratory is described wherein gas chromatography-mass spectroscopy (GC-MS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) are used to characterize the products of a series of microscale reactions on vanillin. A single sophisticated instrument can be incorporated into the laboratory given sufficient attention to the use of sampling accessories and software macros. Synthetic experiments coupled with modern instrumental techniques can be used in the general chemistry laboratory to illustrate the concepts of synthesis, structure, bonding, and spectroscopy.

  12. Synthesis of mesomeric betaine compounds with imidazolium-enolate structure

    Directory of Open Access Journals (Sweden)

    Nina Gonsior

    2012-03-01

    Full Text Available The synthesis of a heterocyclic mesomeric betaine by quaternization reaction of 1-butylimidazole and tetrabromo-1,4-benzoquinone is presented. The structure was verified by means of X-ray single-crystal analysis, NMR and IR spectroscopy. Inclusion complexes of the heterocyclic mesomeric betaine with randomly methylated (1.8 β-cyclodextrin were investigated by UV–vis spectroscopy. Furthermore, the reaction conditions were applied to poly(vinylimidazole and 1,4-bis(1H-imidazol-1-ylbutane to obtain functionalized polymer networks and condensate polymers, respectively.

  13. Synthesis and Structural Studies of 1-Deoxybaccatin VI Derivatives

    Institute of Scientific and Technical Information of China (English)

    LIN,Hai-Xia; WANG,Dian-Long; CHEN,Jian-Min; CHEN,Min-Qin

    2008-01-01

    Synthesis and crystal structures of 1-deoxybaccatin VI derivatives, and the influence of C(9), C(10), and C(13) substituents of the tetracyclic moiety on molecular conformations were investigated. Comparison of conformations of 1-deoxybaccatin VI derivatives reveals subtle conformational variations in the tetracyclic ring system due to deacetylation at C(10) and C(13), and 9,10-acetonide. Additionally, C(2)-benzoyl group exhibits an unexpected conformational flexibility in 1-deoxybaccatin VI derivatives, which may be relevant to the bioactivity of taxanes.

  14. Synthesis and Structural Study of Some Pyrimidinium Hexafluoridosilicates.

    Science.gov (United States)

    Pevec, Andrej

    2015-01-01

    The synthesis and spectroscopic characterization of some pyrimidinium hexafluoridosilicate salts with the formula (RH)2[SiF]6 (where R = 2-aminopyrimidine (1), cytosine (2) and 5-cyanocytosine (3)) is obtained in the reaction of SiO2 with hydrofluoric acid solution and subsequent addition of 2-aminopyrimidine, cytosine or 4-amino-2-chloropyrimidine-5-carbonitrile. The crystal structures of 1 and 3 have been determined by single-crystal X‒ray diffraction analysis. The combination of N‒H···F hydrogen bonds along with π‒π interactions between aromatic rings resulted in supramolecular architecture of cations and anions in the solid state. PMID:26085410

  15. Synthesis and Structural Analysis of Polyester Prodrugs of Norfloxacin

    Directory of Open Access Journals (Sweden)

    Waclaw Kolodziejski

    2008-01-01

    Full Text Available Two-, three- and four-arm, star-shaped poly(ε-caprolactone andpoly(D,L-lactide homopolymers, and copolymers of ε-caprolactone with D,L-lactide weresynthesized via ring-opening polymerization of cyclic esters in the presence of glycerol,penthaerythritol and poly(ethylene glycol as initiators and stannous octoate as a catalyst.Thus obtained oligomers were successfully used in the synthesis of novel macromolecularprodrugs of norfloxacin. The structures of the polymers and prodrugs were elucidated bymeans of MALDI-TOF MS, NMR and IR studies.

  16. Schiff base functionalized Organopropylsilatranes: Synthesis and structural characterization

    Indian Academy of Sciences (India)

    Gurjaspreet Singh; Promila; Amandeep Saroa; Jandeep Singh; Raj Pal Sharm; V Ferretti

    2016-02-01

    Synthesis of Schiff bases linked to organopropylsilatranes were performed by condensation reaction of post-functionalized silatranes such as aminopropylsilatrane (4), aminopropyl-3,7,10-trimethylsilatrane (5) and N-substituted aminopropylsilatrane (10) with two different aldehydes viz. pyrrole-2-carboxaldehyde and 2-hydroxy-1-napthaldehyde. The resulting Schiff base substituted silatranes were well characterized by elemental analysis, spectroscopic studies [IR, (1H, 13C) NMR, and MS]. The structures of two silatranes were confirmed by single crystal X-ray diffraction analysis.

  17. Substrate-Controlled Asymmetric Total Synthesis and Structure Revision of (-)-Bisezakyne A.

    Science.gov (United States)

    Shin, Iljin; Lee, Dongjoo; Kim, Hyoungsu

    2016-09-01

    The first asymmetric total synthesis and subsequent structure revision of (-)-bisezakyne A, a Laurencia C15 acetogenin from Alpysia oculifera, has been accomplished. Our substrate-controlled synthesis of this oxolane natural product features a highly stereoselective "protecting-group-dependent" intramolecular amide enolate alkylation strategy for the synthesis of the key 9,10-trans-9,12-cis-10-hydroxytetrahydrofuran intermediate through "nonchelate" control. In addition, our synthesis determined the absolute configuration of the halogenated marine natural product. PMID:27551943

  18. System for Structural Synthesis Combines Finite-Element Analysis and Optimization Programs

    Science.gov (United States)

    Rogers, J. L., Jr.

    1984-01-01

    Programming System for Structural Synthesis, EAL/PROSSS, provides structural-synthesis capability by combining EAL and CONMIN computer programs with set of interface procedures. EAL is general-purpose finiteelement structural-analysis program; CONMIN is general-purpose optimization program. User supplies two smaller problem-dependent programs to define design variables, constraints, and objective function.

  19. Synthesis of Carbon nano structures by plasma discharge

    International Nuclear Information System (INIS)

    Due to the great quantity of applications of the carbon nano structures (NEC) in diverse areas like: synthesis of super-resistant materials, hydrogen storage, nano sensors generation and nano catalysts, it has seen the necessity to generate new processes of synthesis of this materials as well as to already improve those existent. The present work has as objective to optimize the NEC synthesis process by means of the electric arc method which uses alternating current to high frequencies (HF), obtaining relatively clean products; that is to say, it hardly presents amorphous material neither sludges. They stand out the obtaining of carbon nano fibers (NFC) by means of a luminescent-arch discharge, in a gas mixture of He-CH4 with 34% at. Ni/10.32% at.Y like catalyst; at a frequency of 42 kHz and low power (300 W). This method benefits the amass of the particles in both electrodes due to the high frequencies. The time of duration of the process oscillates between 5 and 20 minutes. The obtained product was characterized by scanning electron microscopy (MEB), transmission electron microscopy (MET) to determine the NEC type obtained and by X-ray diffraction analysis and Raman spectroscopy for determining the purity of the samples. The NFC is relatively free of amorphous coal. The surface and structural analysis indicates that the fibers have a half diameter of 80 nm. It is also made, a study by optical emission spectroscopy of plasma using the Swan band for determining the temperature. (Author)

  20. Synthesis, structure characterization and catalytic activity of nickel tungstate nanoparticles

    International Nuclear Information System (INIS)

    Graphical abstract: NiWO4 nanoparticles were prepared via precipitation technique. Experimental parameters of procedure were optimized statistically. Highlights: ► NiWO4 spherical nanoparticles were synthesized via direct precipitation method. ► Taguchi robust design was used for optimization of synthesis reaction parameters. ► Composition and structural properties of NiWO4 nanoparticles were characterized. ► EDAX, XRD, SEM, FT-IR, UV–vis and photoluminescence techniques were employed. ► Catalytic activity of the product in a cyclo-addition reaction was investigated. - Abstract: Taguchi robust design was applied to optimize experimental parameters for controllable, simple and fast synthesis of nickel tungstate nanoparticles. NiWO4 nanoparticles were synthesized by precipitation reaction involving addition of nickel ion solution to the tungstate aqueous reagent and then formation of nickel tungstate nucleolus which are insoluble in aqueous media. Effects of various parameters such as nickel and tungstate concentrations, flow rate of reagent addition and reactor temperature on diameter of synthesized nickel tungstate nanoparticles were investigated experimentally by the aid of orthogonal array design. The results for analysis of variance (ANOVA) showed that particle size of nickel tungstate can be effectively tuned by controlling significant variables involving nickel and tungstate concentrations and flow rate; while, temperature of the reactor has a no considerable effect on the size of NiWO4 particles. The ANOVA results proposed the optimum conditions for synthesis of nickel tungstate nanoparticles via this technique. Also, under optimum condition nanoparticles of NiWO4 were prepared and their structure and chemical composition were characterized by means of EDAX, XRD, SEM, FT-IR spectroscopy, UV–vis spectroscopy, and photoluminescence. Finally, catalytic activity of the nanoparticles in a cycloaddition reaction was examined.

  1. Synthesis, structure characterization and catalytic activity of nickel tungstate nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Pourmortazavi, Seied Mahdi, E-mail: pourmortazavi@yahoo.com [Faculty of Material and Manufacturing Technologies, Malek Ashtar University of Technology, Tehran (Iran, Islamic Republic of); Rahimi-Nasrabadi, Mehdi, E-mail: rahiminasrabadi@gmail.com [Department of Chemistry, Imam Hossein University, Tehran (Iran, Islamic Republic of); Khalilian-Shalamzari, Morteza [Department of Chemistry, Imam Hossein University, Tehran (Iran, Islamic Republic of); Zahedi, Mir Mahdi; Hajimirsadeghi, Seiedeh Somayyeh [Islamic Azad University, Varamin Pishva Branch, Varamin (Iran, Islamic Republic of); Omrani, Ismail [Department of Chemistry, Imam Hossein University, Tehran (Iran, Islamic Republic of)

    2012-12-15

    Graphical abstract: NiWO{sub 4} nanoparticles were prepared via precipitation technique. Experimental parameters of procedure were optimized statistically. Highlights: Black-Right-Pointing-Pointer NiWO{sub 4} spherical nanoparticles were synthesized via direct precipitation method. Black-Right-Pointing-Pointer Taguchi robust design was used for optimization of synthesis reaction parameters. Black-Right-Pointing-Pointer Composition and structural properties of NiWO{sub 4} nanoparticles were characterized. Black-Right-Pointing-Pointer EDAX, XRD, SEM, FT-IR, UV-vis and photoluminescence techniques were employed. Black-Right-Pointing-Pointer Catalytic activity of the product in a cyclo-addition reaction was investigated. - Abstract: Taguchi robust design was applied to optimize experimental parameters for controllable, simple and fast synthesis of nickel tungstate nanoparticles. NiWO{sub 4} nanoparticles were synthesized by precipitation reaction involving addition of nickel ion solution to the tungstate aqueous reagent and then formation of nickel tungstate nucleolus which are insoluble in aqueous media. Effects of various parameters such as nickel and tungstate concentrations, flow rate of reagent addition and reactor temperature on diameter of synthesized nickel tungstate nanoparticles were investigated experimentally by the aid of orthogonal array design. The results for analysis of variance (ANOVA) showed that particle size of nickel tungstate can be effectively tuned by controlling significant variables involving nickel and tungstate concentrations and flow rate; while, temperature of the reactor has a no considerable effect on the size of NiWO{sub 4} particles. The ANOVA results proposed the optimum conditions for synthesis of nickel tungstate nanoparticles via this technique. Also, under optimum condition nanoparticles of NiWO{sub 4} were prepared and their structure and chemical composition were characterized by means of EDAX, XRD, SEM, FT-IR spectroscopy, UV

  2. Synthesis, structure and biological properties of active spirohydantoin derivatives

    Directory of Open Access Journals (Sweden)

    Lazić Anita M.

    2016-01-01

    Full Text Available Spirohidantoins represent an pharmacologically important class of heterocycles since many derivatives have been recognized that display interesting activities against a wide range of biological targets. First synthesis of cycloalkanespiro-5-hydantoins was performed by Bucherer and Lieb 1934 by the reaction of cycloalkanone, potassium cyanide and ammonium-carbonate at reflux in a mixture of ethanol and water. QSAR (Quantitative Structure-Activity Relationship studies showed that a wide range of biological activities of spirohydantoin derivatives strongly depend upon their structure. This paper describes different methods of synthesis of spirohydantoin derivatives, their physico-chemical properties and biological activity. It emphasizes the importance of cycloalkanespiro-5-hydantoins with anticonvulsant, antiproliferative, antipsychotic, antimicrobial and antiinflammatory properties as well as their importance in the treatment of diabetes. Numerous spirohydantoin compounds exhibit physiological activity such as serotonin and fibrinogen antagonist, inhibitors of the glycine binding site of the NMDA receptor also, antagonist of leukocyte cell adhesion, acting as allosteric inhibitors of the protein-protein interactions. Some spirohydantoin derivatives have been identified as antitumor agents. Their activity depends on the substituent presented at position N-3 of the hydantoin ring and increases in order alkene > ester > ether. Besides that, compounds that contain two electron withdrawing groups (e.g. fluorine or chlorine on the third and fourth position of the phenyl ring are better antitumor agents than compounds with a single electron withdrawing group. [Projekat Ministarstva nauke Republike Srbije, br. 172013

  3. Metathesis of carbon dioxide and phenyl isocyanate catalysed by group(IV) metal alkoxides: An experimental and computational study

    Indian Academy of Sciences (India)

    Akshai Kumar; Ashoka G Samuelson

    2011-01-01

    The insertion reactions of zirconium(IV) -butoxide and titanium(IV) -butoxide with a heterocumulene like carbodiimide, carbon dioxide or phenyl isocyanate are compared. Both give an intermediate which carries out metathesis at elevated temperatures by inserting a second heterocumulene in a head-to-head fashion. The intermediate metallacycle extrudes a new heterocumulene, different from the two that have inserted leading to metathesis. As the reaction is reversible, catalytic metathesis is feasible. In stoichiometric reactions heterocumulene insertion, metathesis and metathesis cum insertion products are observed. However, catalytic amounts of the metal alkoxide primarily led to metathesis products. It is shown that zirconium alkoxides promote catalytic metathesis (isocyanates, carbon dioxide) more efficiently than the corresponding titanium alkoxide. The difference in the metathetic activity of these alkoxides has been explained by a computational study using model complexes Ti(OMe)4 (1bTi) and Zr(OMe)4 (1bZr). The computation was carried out at the B3LYP/LANL2DZ level of theory.

  4. Structural synthesis of parallel programs (Methodology and Tools

    Directory of Open Access Journals (Sweden)

    G. Cejtlin

    1995-11-01

    Full Text Available Concepts of structured programming and propositional program logics were anticipated in the systems of algorithmic algebras (SAAs introduced by V.M.Glushkov in 1965. This paper correlates the SAA language with the known formalisms describing logic schemes of structured and unstructured programs. Complete axiomatics is constructed for modified SAAs (SAA-M oriented towards the formalization of parallel computations and abstract data types. An apparatus formalizing (top-down, bottom-up, or combined design of programs is suggested that incorporates SAA-M, grammar and automaton models oriented towards multiprocessing. A method and tools of parallel program design are developed. They feature orientation towards validation, transformations and synthesis of programs.

  5. Identification of structural interface characteristics using component mode synthesis

    Science.gov (United States)

    Huckelbridge, A. A.; Lawrence, C.

    1989-01-01

    The inability to adequately model connections has limited the ability to predict overall system dynamic response. Connections between structural components are often mechanically complex and difficult to accurately model analytically. Improved analytical models for connections are needed to improve system dynamic predictions. This study explores combining Component Mode synthesis methods for coupling structural components with Parameter Identification procedures for improving the analytical modeling of the connections. Improvements in the connection properties are computed in terms of physical parameters so the physical characteristics of the connections can be better understood, in addition to providing improved input for the system model. Two sample problems, one utilizing simulated data, the other using experimental data from a rotor dynamic test rig, are presented.

  6. Dual methods and approximation concepts in structural synthesis

    Science.gov (United States)

    Fleury, C.; Schmit, L. A., Jr.

    1980-01-01

    Approximation concepts and dual method algorithms are combined to create a method for minimum weight design of structural systems. Approximation concepts convert the basic mathematical programming statement of the structural synthesis problem into a sequence of explicit primal problems of separable form. These problems are solved by constructing explicit dual functions, which are maximized subject to nonnegativity constraints on the dual variables. It is shown that the joining together of approximation concepts and dual methods can be viewed as a generalized optimality criteria approach. The dual method is successfully extended to deal with pure discrete and mixed continuous-discrete design variable problems. The power of the method presented is illustrated with numerical results for example problems, including a metallic swept wing and a thin delta wing with fiber composite skins.

  7. Shock wave synthesis of aluminium nitride with rocksalt structure

    Science.gov (United States)

    Keller, K.; Schlothauer, T.; Schwarz, M.; Heide, G.; Kroke, E.

    2012-03-01

    The high pressure phase of aluminium nitride with rocksalt structure (rs) is a ceramic with high potential and a challenging material to investigate. The rs-AlN was synthesised and recovered by shock wave experiments using the flyer-plate method with multiple reflections at peak pressures between 15 and 43 GPa. Successful syntheses were carried out using AlN nanopowder with ambient pressure wurtzite structure (w-AlN) as starting material. The high pressure modification could, however, not be obtained when starting from submicron w-AlN. The recovery of rs-AlN is sensitive to the synthesis conditions as these influence the reconversion of rs-AlN to w-AlN.

  8. Hydrothermal synthesis as a route to mineralogically-inspired structures.

    Science.gov (United States)

    McMillen, Colin D; Kolis, Joseph W

    2016-02-21

    The use of high temperature hydrothermal reactions to prepare crystals having mineralogically-related structures is described. Complex naturally occurring minerals can have fascinating structures and exhibit important features like low dimensionality, noncentrosymmetry, or ion channels that can provide excellent guideposts for the designed synthesis of new materials. Actual minerals, even though they may have intriguing physical properties, are often unsuitable for study because of the persistent impurities inevitably present in natural samples. Hydrothermal fluids at relatively high temperatures provide access to large, high quality single crystals of structures with mineral-like structures. This enables the study of physical properties like ionic conduction, magnetic spin frustration and non-linear optical behavior. Some fundamental considerations of the hydrothermal technique are discussed in the context of synthesizing mineralogically-inspired materials. The metal vanadates provide a surprisingly rich and diversified range of compounds and are selected to illustrate many of the concepts described here. A series of low dimensional mineral analogs featuring isolated units, chains, and layers have been prepared in the laboratory as large single crystals using a high temperature hydrothermal synthetic methods, and their physical properties are under investigation. The metal silicates are also highlighted as another promising field of exploration, since their hydrothermal synthesis surprisingly lags behind the enormous literature of the natural silicate minerals. The introduction of heteroelements, such as boron to make borosilicates, appears to also open the door to additional new materials. Many of these new materials have direct equivalents in the mineral kingdom, while others have no known analogs but are reminiscent of minerals and can be classified in the same ways. From these initial results there appears to be a very rich vein of synthetic minerals waiting

  9. Synthesis of Au nanowires with controlled morphological and structural characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Gurvinder, E-mail: gurvinder.singh@ntnu.no [Ugelstad Laboratory, Department of Chemical Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim (Norway); Helvoort, Antonius T.J. van [Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim (Norway); Bandyopadhyay, Sulalit; Volden, Sondre; Andreassen, Jens-Petter [Ugelstad Laboratory, Department of Chemical Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim (Norway); Glomm, Wilhelm R., E-mail: Wilhelm.Glomm@sintef.no [Ugelstad Laboratory, Department of Chemical Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim (Norway); SINTEF Materials and Chemistry, Biotechnology and Nanomedicine Sector, NO-7491 Trondheim (Norway)

    2014-08-30

    Graphical abstract: - Highlights: • Synthesis of metal nanowires. • Control over structural and morphological characteristics via seed type nanoparticle. • Growth via surfactant or surface diffusion process. • Structural and surface characterization. - Abstract: A growth of one-dimensional noble metal nanostructure with controlled structural characteristic has been under intense investigation as the physical properties, for example, mechanical and electrical properties highly depend on the crystallinity of the nanostructure. Herein, we report a seed-mediated growth of gold nanowires with controlled structural and morphological characteristics, which can easily be varied by selecting appropriate seed nanoparticles, either spherical or rod type in aqueous solution at room temperature. The growth of nanowires was monitored by characterizing the samples at different time period during the reaction, and our observations suggest that growth occurs from seeds rapidly growing along one-dimension followed by surfactant induced fusion or welding and surface diffusion. The aspect ratio and morphology of these NWs can be tuned by CTAB concentration, pH and temperature of the growth solution. We show that the aspect ratio and morphology of these NWs can be tuned by the surfactant concentration, pH and temperature of the growth solution. Electron microscopy and X-ray Photoelectron spectroscopic techniques were employed for investigating structural and surface characteristics of nanowires. This approach can possibly help to synthesize nanowires of other metals with controlled crystalline behaviour which is highly essential for understanding their properties and practical applications in nanoelectronics, optical devices, catalysis, and sensors.

  10. Single-step synthesis of well-crystallized and pure barium titanate nanoparticles in supercritical fluids

    Science.gov (United States)

    Reverón, Helen; Aymonier, Cyril; Loppinet-Serani, Anne; Elissalde, Catherine; Maglione, Mario; Cansell, François

    2005-08-01

    Single-step synthesis of ultra-fine barium titanate powder with a crystallinity as high as 90% and without barium carbonate contamination has been successfully performed under supercritical conditions using a continuous-flow reactor in the temperature range 150-380 °C at 16 MPa. To synthesize this bimetallic oxide, alkoxides, ethanol and water were used. The influence of the synthesis parameters on the BaTiO3 powder characteristics was investigated. The results show that the water to alkoxide precursor ratio, the reactor temperature and the Ba:Ti molar ratio of alkoxide precursor play a major role in the crystallization of pure and well-crystallized BaTiO3 nanoparticles. The continuous mode of operation without post-treatments for powder washing, drying or crystallization increase the industrial interest.

  11. Synthesis, structure characterization and catalytic activity of nickel tungstate nanoparticles

    Science.gov (United States)

    Pourmortazavi, Seied Mahdi; Rahimi-Nasrabadi, Mehdi; Khalilian-Shalamzari, Morteza; Zahedi, Mir Mahdi; Hajimirsadeghi, Seiedeh Somayyeh; Omrani, Ismail

    2012-12-01

    Taguchi robust design was applied to optimize experimental parameters for controllable, simple and fast synthesis of nickel tungstate nanoparticles. NiWO4 nanoparticles were synthesized by precipitation reaction involving addition of nickel ion solution to the tungstate aqueous reagent and then formation of nickel tungstate nucleolus which are insoluble in aqueous media. Effects of various parameters such as nickel and tungstate concentrations, flow rate of reagent addition and reactor temperature on diameter of synthesized nickel tungstate nanoparticles were investigated experimentally by the aid of orthogonal array design. The results for analysis of variance (ANOVA) showed that particle size of nickel tungstate can be effectively tuned by controlling significant variables involving nickel and tungstate concentrations and flow rate; while, temperature of the reactor has a no considerable effect on the size of NiWO4 particles. The ANOVA results proposed the optimum conditions for synthesis of nickel tungstate nanoparticles via this technique. Also, under optimum condition nanoparticles of NiWO4 were prepared and their structure and chemical composition were characterized by means of EDAX, XRD, SEM, FT-IR spectroscopy, UV-vis spectroscopy, and photoluminescence. Finally, catalytic activity of the nanoparticles in a cycloaddition reaction was examined.

  12. Fast and reversible insertion of carbon dioxide into zirconocene-alkoxide bonds. A mechanistic study.

    Science.gov (United States)

    Brink, Alice; Truedsson, Ida; Fleckhaus, André; Johnson, Magnus T; Norrby, Per Ola; Roodt, Andreas; Wendt, Ola F

    2014-06-21

    In two consecutive equilibria the compound (Cp*)2Zr(OMe)2 undergoes insertion of CO2 to form the mono- and bis-hemicarbonates. Both equilibria are exothermic but entropically disfavoured. Magnetisation transfer experiments gave kinetic data for the first equilibrium showing that the rate of insertion is overall second order with a rate constant of 3.20 ± 0.12 M(-1) s(-1), which is substantially higher than those reported for other early transition metal alkoxides, which are currently the best homogeneous catalysts for dimethyl carbonate formation from methanol and CO2. Activation parameters for the insertion reaction point to a highly ordered transition state and we interpret that as there being a substantial interaction between the CO2 and the metal during the C-O bond formation. This is supported by DFT calculations showing the lateral attack by CO2 to have the lowest energy transition state. PMID:24796283

  13. Graphene Oxide: Synthesis, Characterization, Electronic Structure, and Applications

    Science.gov (United States)

    Stewart, Derek A.; Mkhoyan, K. Andre

    While graphite oxide was first identified in 1855 [1, 2], the recent discovery of stable graphene sheets has led to renewed interest in the chemical structure and potential applications of graphene oxide sheets. These structures have several physical properties that could aid in the large scale development of a graphene electronics industry. Depending on the degree of oxidization, graphene oxide layers can be either semiconducting or insulating and provide an important complement to metallic graphene layers. In addition, the electronic and optical properties of these films can be controlled by the selective removal or addition of oxygen. For example, selective oxidationof graphene sheets could lead to electronic circuit fabrication on the scale of a single atomic layer. Graphene oxide is also dispersible in water and other solvents and this provides a facile route for graphene deposition on a wide range of substrates for macroelectronics applications. Although graphite oxide has been known for roughly 150 years, key questions remain in regards to its chemical structure, electronic properties, and fabrication. Answering these issues has taken on special urgency with the development of graphene electronics. In this chapter, we will provide an overview of the field with special focus on synthesis, characterization, and first principles analysis of bonding and electronic structures. Finally, we will also address some of the most promising applications for graphene oxide in electronics and other industries.

  14. Total synthesis and structural revision of vannusals A and B: synthesis of the originally assigned structure of vannusal B.

    Science.gov (United States)

    Nicolaou, K C; Ortiz, Adrian; Zhang, Hongjun; Dagneau, Philippe; Lanver, Andreas; Jennings, Michael P; Arseniyadis, Stellios; Faraoni, Raffaella; Lizos, Dimitrios E

    2010-05-26

    The total synthesis of the originally assigned structure of vannusal B (2) and its diastereomer (d-2) are described. Initial forays into these structures with model systems revealed the viability of a metathesis-based approach and a SmI(2)-mediated strategy for the key cyclization to forge the central region of the molecule, ring C. The former approach was abandoned in favor of the latter when more functionalized substrates failed to enter the cyclization process. The successful, devised convergent strategy based on the SmI(2)-mediated ring closure utilized vinyl iodide (-)-26 and aldehyde fragment (+/-)-86 as key building blocks, whose lithium-mediated coupling led to isomeric coupling products (+)-87 and (-)-88 (as shown in Scheme 17 in the article). Intermediate (-)-88 was converted, via (-)-89 and (-)-90/(+)-91, to vannusal B structure 2 (as shown in Scheme 18 in the article), whose spectroscopic data did not match those reported for the natural product. Similarly, intermediate (+)-25, obtained through coupling of vinyl iodide (-)-26 and aldehyde (+/-)-27 (as shown in Scheme 13 in the article) was transformed via intermediates (-)-97 and (+)-98 (as shown in Scheme 19 in the article) to diastereomeric vannusal B structure (+)-d-2 (as shown in Scheme 19 in the article) which was also proven spectroscopically to be non-identical to the naturally occurring substance. These investigations led to the discovery and development of a number of new synthetic technologies that set the stage for the solution of the vannusal structural conundrum. PMID:20443561

  15. Structural analogues of diosgenyl saponins: synthesis and anticancer activity.

    Science.gov (United States)

    Kaskiw, Matthew J; Tassotto, Mary Lynn; Mok, Mac; Tokar, Stacey L; Pycko, Roxanne; Th'ng, John; Jiang, Zi-Hua

    2009-11-15

    Saponins display various biological activities including anti-tumor activity. Recently intensive research has been focused on developing saponins for tumor therapies. The diosgenyl saponin dioscin is one of the most common steroidal saponins and exhibits potent anticancer activity in several human cancer cells through apoptosis-inducing pathways. In this paper, we describe the synthesis of several diosgenyl saponin analogues containing either a 2-amino-2-deoxy-beta-d-glucopyranosyl residue or an alpha-l-rhamnopyranosyl-(1-->4)-2-amino-2-deoxy-beta-d-glucopyranosyl residue with different acyl substituents on the amino group. The cytotoxic activity of these compounds was evaluated in MCF-7 breast cancer cells and HeLa cervical cancer cells. Structure-activity relationship studies show that the disaccharide saponin analogues are in general less active than their corresponding monosaccharide analogues. The incorporation of an aromatic nitro functionality into these saponin analogues does not exhibit significant effect on their cytotoxic activity. PMID:19819703

  16. A new structural analysis/synthesis capability - ACCESS. [Approximation Concepts Code for Efficient Structural Synthesis

    Science.gov (United States)

    Schmit, L. A.; Miura, H.

    1975-01-01

    The creation of an efficient automated capability for minimum weight design of structures is reported. The ACCESS 1 computer program combines finite element analysis techniques and mathematical programming algorithms using an innovative collection of approximation concepts. Design variable linking, constraint deletion techniques and approximate analysis methods are used to generate a sequence of small explicit mathematical programming problems which retain the essential features of the design problem. Organization of the finite element analysis is carefully matched to the design optimization task. The efficiency of the ACCESS 1 program is demonstrated by giving results for several example problems.

  17. Epitaxial growth of BaZrO{sub 3} films on single crystal oxide substrates using sol-gel alkoxide precursors

    Energy Technology Data Exchange (ETDEWEB)

    Paranthaman, M.; Shoup, S.S.; Beach, D.B.; Williams, R.K.; Specht, E.D. [Oak Ridge National Lab., TN (United States)

    1997-12-01

    Epitaxial BaZrO{sub 3} (barium zirconium oxide) films were grown on single crystal substrates. A BaZrO{sub 3} precursor solution was prepared by sol-gel synthesis using an all-alkoxide route. The barium precursors were prepared by reacting barium metal with 2-methoxyethanol, and zirconium precursors were prepared by exchanging ligands between zirconium n-propoxide and 2-methoxyethanol. The resulting BaZrO{sub 3} precursor solution was partially hydrolyzed and spin-coated on sapphire (100), SrTiO{sub 3} (strontium titanium oxide) (100), and LaAlO{sub 3} (lanthanum aluminum oxide) (100) substrates. The films were post-annealed in oxygen at 800 C for 2 min in a rapid thermal annealer. The coating and the annealing procedures were repeated three times to obtain the desired thickness, 300 nm. X-ray diffraction studies showed the presence of a single (100) cube texture for BaZrO{sub 3} films on SrTiO{sub 3} and LaAlO{sub 3} substrates. The BaZrO{sub 3} films grown on sapphire had a random texture. The BaZrO{sub 3} films grown on SrTiO{sub 3} substrates had a sharp texture compared to that on LaAlO{sub 3} substrates. This may be due to the relatively smaller lattice mismatch between SrTiO{sub 3} and BaZrO{sub 3}.

  18. Synthesis, structure and ESR studies of Mg doped ZnAlO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Cakiroglu, O. [Istanbul University, Hasan Ali Yucel Education Faculty, Beyazit, 34452 Istanbul (Turkey); Acikgoz, M. [Bahcesehir University, Faculty of Arts and Sciences, Department of Mathematics and Computer Sciences, Besiktas, 34349 Istanbul (Turkey); Arda, L., E-mail: lutfi.arda@bahcesehir.edu.tr [Bahcesehir University, Faculty of Arts and Sciences, Department of Mathematics and Computer Sciences, Besiktas, 34349 Istanbul (Turkey); Akcan, D. [Bahcesehir University, Faculty of Arts and Sciences, Department of Mathematics and Computer Sciences, Besiktas, 34349 Istanbul (Turkey); Dogan, N. [Gebze Institute of Technology, Department of Physics, 41400 Gebze/Kocaeli (Turkey)

    2015-01-01

    Zn{sub 0.98−x}Mg{sub x}Al{sub 0.02}O solutions with different (x=0.05, 0.10, 0.15, and 0.20) compositions were synthesized by the sol–gel technique using Zn, Mg and Al based alkoxide. The effects of highly Mg doping ratio on structure and magnetic properties were investigated systematically. The phase and the crystal structure of the Zn{sub 0.98−x}Mg{sub x}Al{sub 0.02}O nanoparticles were characterized using X-ray diffraction. Scanning Electron Microscope and X-ray diffraction were utilized to understand the size and microstructure of samples. We observed the particle sizes of nanoparticles between 80 nm and 100 nm range. Furthermore, ESR spectra of Zn{sub 0.98−x}Mg{sub x}Al{sub 0.02}O nanoparticles were collected at room temperature on a Bruker EMX model X-band spectrometer operating at a frequency of 9.50 GHz. It is observed that the critical concentration of Mg, x=0.1, has minimum g-factor and maximum line-width (W). - Highlights: • Zn{sub 0.98−x}Mg{sub x}Al{sub 0.02}O{sub ,} (0.05≤x≤0.20) nanoparticles were prepared by sol–gel technique. • The Mg concentration is increased, the agglomeration and malting of nanoparticles increase. • Rietveld analysis of ZnMgAlO shows single phase (ZnO) for x<0.2 concentration. • The critical concentration of Mg is x=0.1 to have minimum g-factor and maximum line-width W.

  19. "Common synthetic scaffolds" in the synthesis of structurally diverse natural products.

    Science.gov (United States)

    Anagnostaki, Elissavet E; Zografos, Alexandros L

    2012-09-01

    Selected natural products have long been considered as desirable targets for total synthesis due to their unique biological properties and their challenging structural complexity. Laboratory synthesis of natural compounds usually relies on target-oriented synthesis, involving the production, isolation and purification of successive intermediates, requiring multiple steps to arrive to the final product. A far more economical approach using common synthetic scaffolds that can be readily transformed through biomimetic-like pathways to a range of structurally diverse natural products has been evolved in the last decade, leading synthesis to new directions. This tutorial review critically presents the hallmarks in this field.

  20. Synthesis, Characterization, and Electronic Structure Studies of Cubic Bi1.5ZnTa1.5O7 for Photocatalytic Applications

    Directory of Open Access Journals (Sweden)

    Ganchimeg Perenlei

    2015-01-01

    Full Text Available Bi1.5ZnTa1.5O7 (BZT has been synthesized using an alkoxide based sol-gel reaction route. The evolution of the phases produced from the alkoxide precursors and their properties have been characterized as function of temperature using a combination of thermogravimetric analysis (TGA coupled with mass spectrometry (MS, infrared emission spectrometry (IES, X-ray diffraction (XRD, ultraviolet and visible (UV-Vis spectroscopy, Raman spectroscopy, and N2 adsorption/desorption isotherms. The lowest sintering temperature (600°C to obtain phase pure BZT powders with high surface area (14.5 m2/g has been determined from the thermal decomposition and phase analyses. The photocatalytic activity of the BZT powders has been tested for the decolorization of organic azo-dye and found to be photoactive under UV irradiation. The electronic band structure of the BZT has been investigated using density functional theory (DFT calculations to determine the band gap energy (3.12 eV and to compare it with experimental band gap (3.02 eV at 800°C from optical absorption measurements. An excellent match is obtained for an assumption of Zn cation substitutions at specifically ordered sites in the BZT structure.

  1. 合成钛硅分子筛TS-1的一种新方法%A NOVEL METHOD FOR SYNTHESIS OF TS-1

    Institute of Scientific and Technical Information of China (English)

    周继承; 王祥生

    1999-01-01

    @@ In both conventional method[1] and modified method[2] ,organic Si and Ti alkoxides were used as Si source and Ti source respectively, and only strong organic base was used. So this system may be called as organic synthesis one (see Fig 1 )Thangaraj et al[3] reported that in the organic synthesis system only organic strong base TPAOH can be used.

  2. Lepadiformine: a case study of the value of total synthesis in natural product structure elucidation.

    Science.gov (United States)

    Weinreb, Steven M

    2003-01-01

    Since the emergence of routine X-ray crystallography and high-field FT NMR in the mid-twentieth century, the importance of total synthesis in structure elucidation has become underappreciated by most organic chemists. However, the limitations and fallibility of spectral methodology has recently been highlighted by the mischaracterization of a number of complex natural products, the correct structures of which were all ultimately assigned by total synthesis. This account describes how total synthesis was not only instrumental in disproving the erroneously assigned structure of the marine alkaloid, lepadiformine, but also was also pivotal in establishing the correct structure and absolute configuration.

  3. Synthesis enables a structural revision of the Mycobacterium tuberculosis-produced diterpene, edaxadiene†

    Science.gov (United States)

    Spangler, Jillian E.; Carson, Cheryl A.; Sorensen, Erik J.

    2011-01-01

    A stereodivergent synthesis of the [3.3.1] bicyclic core of edaxadiene was completed utilizing a key intramolecular oxidative ketone allylation. Significant discrepancies between the spectroscopic data obtained for the synthetic construct and the natural isolate raised questions about the structural assignment of edaxadiene. A subsequent structural reassignment was validated by completion of a total synthesis of the correct structure of the natural product. PMID:22114734

  4. LiOOt-Bu as a terminal oxidant in a titanium alkoxide-mediated [2+2+2] reaction cascade☆

    Science.gov (United States)

    Kim, Wan Shin; Aquino, Claudio; Mizoguchi, Haruki; Micalizio, Glenn C.

    2015-01-01

    LiOOt-Bu is an effective oxidant for converting the penultimate organometallic intermediate generated in a titanium alkoxide-mediated [2+2+2] reaction cascade to an allylic alcohol. Oxidation of the presumed allylic titanium species is highly regioselective, providing direct access to substituted hydroindanes containing a primary allylic alcohol. In addition to demonstrating the feasibility of this oxidation process, we document the ability to convert the primary allylic alcohol products to angularly substituted cis-fused hydroindanes. PMID:26097265

  5. Sciduction: Combining Induction, Deduction, and Structure for Verification and Synthesis

    OpenAIRE

    Seshia, Sanjit A.

    2012-01-01

    Even with impressive advances in automated formal methods, certain problems in system verification and synthesis remain challenging. Examples include the verification of quantitative properties of software involving constraints on timing and energy consumption, and the automatic synthesis of systems from specifications. The major challenges include environment modeling, incompleteness in specifications, and the complexity of underlying decision problems. This position paper proposes sciductio...

  6. Uncertainty Modeling for Structural Control Analysis and Synthesis

    Science.gov (United States)

    Campbell, Mark E.; Crawley, Edward F.

    1996-01-01

    The development of an accurate model of uncertainties for the control of structures that undergo a change in operational environment, based solely on modeling and experimentation in the original environment is studied. The application used throughout this work is the development of an on-orbit uncertainty model based on ground modeling and experimentation. A ground based uncertainty model consisting of mean errors and bounds on critical structural parameters is developed. The uncertainty model is created using multiple data sets to observe all relevant uncertainties in the system. The Discrete Extended Kalman Filter is used as an identification/parameter estimation method for each data set, in addition to providing a covariance matrix which aids in the development of the uncertainty model. Once ground based modal uncertainties have been developed, they are localized to specific degrees of freedom in the form of mass and stiffness uncertainties. Two techniques are presented: a matrix method which develops the mass and stiffness uncertainties in a mathematical manner; and a sensitivity method which assumes a form for the mass and stiffness uncertainties in macroelements and scaling factors. This form allows the derivation of mass and stiffness uncertainties in a more physical manner. The mass and stiffness uncertainties of the ground based system are then mapped onto the on-orbit system, and projected to create an analogous on-orbit uncertainty model in the form of mean errors and bounds on critical parameters. The Middeck Active Control Experiment is introduced as experimental verification for the localization and projection methods developed. In addition, closed loop results from on-orbit operations of the experiment verify the use of the uncertainty model for control analysis and synthesis in space.

  7. Structure, Mechanics and Synthesis of Nanoscale Carbon and Boron Nitride

    Science.gov (United States)

    Rinaldo, Steven G.

    This thesis is divided into two parts. In Part I, we examine the properties of thin sheets of carbon and boron nitride. We begin with an introduction to the theory of elastic sheets, where the stretching and bending modes are considered in detail. The coupling between stretching and bending modes is thought to play a crucial role in the thermodynamic stability of atomically-thin 2D sheets such as graphene. In Chapter 2, we begin by looking at the fabrication of suspended, atomically thin sheets of graphene. We then study their mechanical resonances which are read via an optical transduction technique. The frequency of the resonators was found to depend on their temperature, as was their quality factor. We conclude by offering some interpretations of the data in terms of the stretching and bending modes of graphene. In Chapter 3, we look briefly at the fabrication of thin sheets of carbon and boron nitride nanotubes. We examine the structure of the sheets using transmission and scanning electron microscopy (TEM and SEM, respectively). We then show a technique by which one can make sheets suspended over a trench with adjustable supports. Finally, DC measurements of the resistivity of the sheets in the temperature range 600 -- 1400 C are presented. In Chapter 4, we study the folding of few-layer graphene oxide, graphene and boron nitride into 3D aerogel monoliths. The properties of graphene oxide are first considered, after which the structure of graphene and boron nitride aerogels is examined using TEM and SEM. Some models for their structure are proposed. In Part II, we look at synthesis techniques for boron nitride (BN). In Chapter 5, we study the conversion of carbon structures of boron nitride via the application of carbothermal reduction of boron oxide followed by nitridation. We apply the conversion to a wide variety of morphologies, including aerogels, carbon fibers and nanotubes, and highly oriented pyrolytic graphite. In the latter chapters, we look at the

  8. Thermomechanical properties of aluminum alkoxide (alucone) films created using molecular layer deposition

    International Nuclear Information System (INIS)

    Nanometer-scale-thick, polymer-like coatings deposited using the molecular layer deposition (MLD) technique constitute a new class of materials. The modulus and hardness of aluminum alkoxide ('alucone') films grown using either homobifunctional or heterobifunctional reactants were measured using nanoindentation. Because the coatings are brittle and possess a significant tensile film stress immediately after deposition, the influence of film stress on the indentation measurements was quantified using a numerical analysis protocol. The film stress and coefficient of thermal expansion for alucone were determined using the wafer curvature method. Film stress was found to stabilize within the first thermal cycle, demonstrating a repeatable hysteresis thereafter. Curvature/time measurements on coated microcantilever beams indicated that the most significant evolution in film stress for alucone occurred during the initial 2 weeks of storage in the ambient environment. The temporal behavior is attributed to the change in thickness and/or modulus of alucone, and is consistent with the film stress becoming more compressive over time. An encapsulating alumina film, coated using the atomic layer deposition technique, was found to suppress the evolution of stress within alucone. The studies here suggest that the alucones have a greater elastic modulus than traditional polymers, are at present quite brittle and are prone to environmental influence. The MLD technique, however, possesses a rich wealth of options that enable the modulus, adhesion and chemical stability of the coatings to be tailored.

  9. Alkoxide-based precursors for direct drawing of metal oxide micro- and nanofibres

    Directory of Open Access Journals (Sweden)

    Tanel Tätte, Medhat Hussainov, Madis Paalo, Marko Part, Rasmus Talviste, Valter Kiisk, Hugo Mändar, Kaija Põhako, Tõnis Pehk, Kaido Reivelt, Marco Natali, Jonas Gurauskis, Ants Lõhmus and Uno Mäeorg

    2011-01-01

    Full Text Available The invention of electrospinning has solved the problem of producing micro- and nanoscaled metal oxide fibres in bulk quantities. However, until now no methods have been available for preparing a single nanofibre of a metal oxide. In this work, the direct drawing method was successfully applied to produce metal oxide (SnO2, TiO2, ZrO2, HfO2 and CeO2 fibres with a high aspect ratio (up to 10 000 and a diameter as small as 200 nm. The sol–gel processing includes consumption of precursors obtained from alkoxides by aqueous or non-aqueous polymerization. Shear thinning of the precursors enables pulling a material into a fibre. This rheological behaviour can be explained by sliding of particles owing to external forces. Transmission (propagation of light along microscaled fibres and their excellent surface morphology suggest that metal oxide nanofibres can be directly drawn from sol precursors for use in integrated photonic systems.

  10. Alkoxide-based precursors for direct drawing of metal oxide micro- and nanofibres

    Energy Technology Data Exchange (ETDEWEB)

    Taette, Tanel; Hussainov, Medhat; Paalo, Madis; Part, Marko; Talviste, Rasmus; Kiisk, Valter; Maendar, Hugo; Pohako, Kaija; Reivelt, Kaido; Lohmus, Ants [Institute of Physics, University of Tartu, Riia 142, Tartu 51014 (Estonia); Pehk, Tonis [National Institute of Chemical and Biological Physics, Akadeemia tee 23, Tallinn 12618 (Estonia); Natali, Marco [ICIS-CNR, Corso Stati Uniti 4, Padova 35127 (Italy); Gurauskis, Jonas [Instituto de Ciencia de Materiales de Aragon C.S.I.C., University of Zaragoza Fac. De Ciencias, c/Pedro Cerbuna 12, Zaragoza 50009 (Spain); Maeeorg, Uno, E-mail: tanelt@fi.tartu.ee [Institute of Chemistry, University of Tartu, Ravila 14a, Tartu 50411 (Estonia)

    2011-06-15

    The invention of electrospinning has solved the problem of producing micro- and nanoscaled metal oxide fibres in bulk quantities. However, until now no methods have been available for preparing a single nanofibre of a metal oxide. In this work, the direct drawing method was successfully applied to produce metal oxide (SnO{sub 2}, TiO{sub 2}, ZrO{sub 2}, HfO{sub 2} and CeO{sub 2}) fibres with a high aspect ratio (up to 10 000) and a diameter as small as 200 nm. The sol-gel processing includes consumption of precursors obtained from alkoxides by aqueous or non-aqueous polymerization. Shear thinning of the precursors enables pulling a material into a fibre. This rheological behaviour can be explained by sliding of particles owing to external forces. Transmission (propagation) of light along microscaled fibres and their excellent surface morphology suggest that metal oxide nanofibres can be directly drawn from sol precursors for use in integrated photonic systems.

  11. Experimental component Mode Synthesis Applied to the Solar Array Type Structure

    OpenAIRE

    Komatsu, Keiji; Sano, Masaaki; SANBONGI, Shigeo; Takashi Kai; TODA, Susumu; 小松, 敬治; 佐野, 政明; 三本木, 茂夫; 甲斐, 高志; 戸田, 勧

    1988-01-01

    A component mode synthesis technique based on experimentally determined modal parameters is presented in this paper. The test structure is a solar array type plate, which is divided into three parts, and four flexible connective parts. In the synthesis, the measured modes are approximated in polynomials to produce rotational degrees of freedom. The results sythesized are in good agreement with the test results obtained from a combined structure.

  12. A Multidimensional Diversity-Oriented Synthesis Strategy for Structurally Diverse and Complex Macrocycles.

    Science.gov (United States)

    Nie, Feilin; Kunciw, Dominique L; Wilcke, David; Stokes, Jamie E; Galloway, Warren R J D; Bartlett, Sean; Sore, Hannah F; Spring, David R

    2016-09-01

    Synthetic macrocycles are an attractive area in drug discovery. However, their use has been hindered by a lack of versatile platforms for the generation of structurally (and thus shape) diverse macrocycle libraries. Herein, we describe a new concept in library synthesis, termed multidimensional diversity-oriented synthesis, and its application towards macrocycles. This enabled the step-efficient generation of a library of 45 novel, structurally diverse, and highly-functionalized macrocycles based around a broad range of scaffolds and incorporating a wide variety of biologically relevant structural motifs. The synthesis strategy exploited the diverse reactivity of aza-ylides and imines, and featured eight different macrocyclization methods, two of which were novel. Computational analyses reveal a broad coverage of molecular shape space by the library and provides insight into how the various diversity-generating steps of the synthesis strategy impact on molecular shape. PMID:27484830

  13. Hafnium oxide gate dielectrics grown from an alkoxide precursor: structure and defects

    International Nuclear Information System (INIS)

    We present an infrared spectroscopy and X-ray diffraction study of hafnium oxide gate dielectric films deposited from hafnium tetra-tert-butoxide, Hf(OC(CH3)3)4. We characterize the crystal phase as a function of thickness and detect the chemical state of impurities in this high-permittivity (high-κ) material. The HfO2 films are composed of monoclinic crystallites in an amorphous matrix. The crystalline fraction increases with increasing film thickness. Infrared spectroscopy is used to obtain information about impurities, which may help to uncover the nature of electrical defects. We detect and quantify for instance the presence of incorporated hydroxyl groups or water that may be responsible for the deviation from ideal HfO2 stoichiometry. The concentration of residual C-H bonds is low. However, carbon is incorporated in an oxidized form, possibly as carbonate

  14. Design and synthesis of paramagnetic probes for structural biology

    NARCIS (Netherlands)

    Liu, Wei-Min

    2013-01-01

    The majority of the work presented in this thesis involves the design and synthesis of paramagnetic NMR probes, including lanthanoids caged probes and spin labels. An overview of the development of different types of lanthanoids caged probes is given. Among all of the reported lanthanoid probes, the

  15. Iron(oxide) ferrofluids: synthesis, structure and catalysis

    NARCIS (Netherlands)

    Butter, Karen

    2003-01-01

    This thesis describes a study on two connecting research subjects concerning ferrofluids, i.e. the synthesis and use of catalytic magnetic colloids and the microstructural behaviour of ferrofluids in general. An interesting application of ferrofluids (dispersions of magnetic colloids) would be their

  16. Component mode synthesis and large deflection vibrations of complex structures. [beams and trusses

    Science.gov (United States)

    Mei, C.

    1984-01-01

    The accuracy of the NASTRAN modal synthesis analysis was assessed by comparing it with full structure NASTRAN and nine other modal synthesis results using a nine-bay truss. A NASTRAN component mode transient response analysis was also performed on the free-free truss structure. A finite element method was developed for nonlinear vibration of beam structures subjected to harmonic excitation. Longitudinal deformation and inertia are both included in the formula. Tables show the finite element free vibration results with and without considering the effects of longitudinal deformation and inertia as well as the frequency ratios for a simply supported and a clamped beam subjected to a uniform harmonic force.

  17. MWW-type titanosilicate synthesis, structural modification and catalytic applications to green oxidations

    CERN Document Server

    Wu, Peng; Xu, Le; Liu, Yueming; He, Mingyuan

    2013-01-01

    This book provides a comprehensive review of a new generation of selective oxidation titanosilicate catalysts with the MWW topology (Ti-MWW) based on the research achievements of the past 12 years. It gives an overview of the synthesis, structure modification and catalytic properties of Ti-MWW. Ti-MWW can readily be prepared by means of direct hydrothermal synthesis with crystallization-supporting agents, using dual-structure-directing agents and a dry-gel conversion technique. It also can be post-synthesized through unique reversible structure transformation and liquid-phase isomorphous subst

  18. Structural study of the controlled hydrothermal synthesis of LiMn2O4 and LixMnyO2

    DEFF Research Database (Denmark)

    Christiansen, Troels Lindahl; Jensen, Kirsten Marie Ørnsbjerg; Shen, Yanbin;

    , a layered structure, which can also be described as a defective spinel structure. Here, we show that both LiMn2O4 and LixMnyO2 nanoparticles can be synthesized from a simple, low-temperature hydrothermal synthesis. By tuning a single synthesis parameter (Li-concentration) each of the 2 structures...

  19. Isolation, structure, and synthesis of viridic acid, a new tetrapeptide mycotoxin of Penicillium viridicatum Westling

    International Nuclear Information System (INIS)

    The isolation of a new toxic metabolite, viridic acid, from Penicillium viridicatum Westling is described. The chemical and spectroscopic properties of the compound are interpreted in terms of the tetrapeptide structure (N,N-dimethyl-o-aminobenzoyl)-glycyl-(N'-methyl-L-valyl)-o-aminobenzoic acid. The structure and chirality of viridic acid were confirmed by total synthesis

  20. ACCESS-2: Approximation Concepts Code for Efficient Structural Synthesis, user's guide

    Science.gov (United States)

    Miura, H.; Schmit, L. A., Jr.

    1978-01-01

    A user's guide is presented for the ACCESS-2 computer program. ACCESS-2 is a research oriented program which implements a collection of approximation concepts to achieve excellent efficiency in structural synthesis. The finite element method is used for structural analysis and general mathematical programming algorithms are applied in the design optimization procedure.

  1. Synthesis of Nano-Particles in Flames

    DEFF Research Database (Denmark)

    Johannessen, Tue

    The scope of this work is to investigate the synthesis of aluminum oxide particles in flames from the combustion of an aluminum alkoxide precursor.A general introduction to particles formation in the gas phase is presented with emphasis on the mechanisms that control the particle morphology after...... energy expression.Furthermore, the model is validated by comparison with experimental data of the flame synthesis of titania by combustion of TiCl4 previously presented by Pratsinis et al. (1996).The combination of particle dynamics and CFD simulations has proved to be an efficient method...

  2. Novel Synthesis of Ferrocenyl Schiff Bases and Crystal Structure

    Institute of Scientific and Technical Information of China (English)

    ZHANG,Hui-Qing; ZHOU,Zhi-Ming; YU,Cong-Xuan

    2004-01-01

    @@ Ferrocenylimines have attracted additional interest due to their versatile utilities. They have been widely used as plant growth regulator, bactericide, fuel dope and new anticarcinogen.[1] And a large amount of ferrocenyl shiff bases were prepared in the past. However, study on ferrocenylimines as directing ortho metalation group (DMG) in the (-)-sparteine meditated synthesis of planar chiral ferrocene has not been reported. Herein, we synthesized a series of ferrocenyl schiff bases for this study.

  3. Synthesis, structure and physicochemical properties of lithium uranovanadate

    International Nuclear Information System (INIS)

    A new chemical compound, i.e. lithium uranovanadate, was synthesized and studied by the methods of X-ray diffraction, IR spectroscopy and thermography. The standard enthalpies of formation of lithium uranovanadate and its dihydrate at 298.15 K were ascertained using reaction and adiabatic vacuum calorimetry. Temperature dependence of heat capacity in the range of 80 - 300 K of crystal LiVUO6 · 2H2O was studied, thermodynamic characteristics of its synthesis being calculated

  4. Controlled synthesis of fluorescent silica nanoparticles inside microfluidic droplets

    OpenAIRE

    Wacker, Josias Basil; Lignos, Ioannis; Parashar, Virendra Kumar; Gijs, Martinus

    2012-01-01

    We study the droplet-based synthesis of fluorescent silica nanoparticles (50–350 nm size) in a microfluidic chip. Fluorescein-isothiocyanate (FITC) dye is first chemically linked to aminopropyl triethoxysilane (APTES) in ethanol and this reaction product is subsequently mixed with tetraethyl orthosilicate (TEOS) to yield a fluorescent silicon alkoxide precursor solution. The latter reacts with an aqueous ethanol–ammonia hydrolysing mixture inside droplets, forming fluorescent silica nanoparti...

  5. Microwave activated combustion synthesis of porous Al-Ti structures for composite reinforcing

    Energy Technology Data Exchange (ETDEWEB)

    Naplocha, Krzysztof, E-mail: krzysztof.naplocha@pwr.wroc.p [Institute of Production Engineering and Automation, Technical University of Wroclaw, ul. Lukasiewicza 5, 50-371 Wroclaw (Poland); Granat, Kazimierz [Institute of Production Engineering and Automation, Technical University of Wroclaw, ul. Lukasiewicza 5, 50-371 Wroclaw (Poland)

    2009-11-03

    A research on porous Al-Ti materials produced by combustion synthesis is presented. Some of the manufactured preforms could be infiltrated with liquid aluminium alloy to obtain locally reinforced castings. The synthesis progress was analysed, as well as a structure formation, its phase composition, homogeneity degree and type of porosity. Cylindrical green compacts were prepared of Al and Ti powders with various stoichiometric ratios. Synthesis was performed in a specially designed microwave reactor, by placing a compact in a waveguide, in intensely focused field. Temperatures recorded by a pyrometer showed that the synthesis propagation accelerated at the moment of Al{sub 3}Ti creation. The highest synthesis temperature was reached by the specimens containing 45-67% Al (all percentages atomic). Microscopic examinations revealed rounded grains, sometimes with cores of solid solution Ti(Al). The grains were basically composed of AlTi{sub 3} that changed to AlTi at the edge. The grain structure was similar in almost all kinds of the specimens, especially in those with higher Al content. Around those grains, envelopes of AlTi and Al{sub 2}Ti were formed. Chemical composition of the matrix was approximately equivalent to stoichiometric ratio of the initial powder mixture. XRD investigations confirmed multiphase structure of the obtained compacts and a slight effect of the Ti powder granularity. Some of the specimens revealed regular structure with interconnected porosity. Those materials containing 75, 67 and 55% Al were used for producing the aluminium alloy-based composites.

  6. Bloch mode synthesis: Ultrafast methodology for elastic band-structure calculations

    Science.gov (United States)

    Krattiger, Dimitri; Hussein, Mahmoud I.

    2014-12-01

    We present a methodology for fast band-structure calculations that is generally applicable to problems of elastic wave propagation in periodic media. The methodology, called Bloch mode synthesis, represents an extension of component mode synthesis, a set of substructuring techniques originally developed for structural dynamics analysis. In Bloch mode synthesis, the unit cell is divided into interior and boundary degrees-of-freedom, which are described, respectively, by a set of normal modes and a set of constraint modes. A combination of these mode sets then forms a reduced basis for the band structure eigenvalue problem. The reduction is demonstrated on a phononic-crystal model and a locally resonant elastic-metamaterial model and is shown to accurately predict the frequencies and Bloch mode shapes with a dramatic decrease in computation time in excess of two orders of magnitude.

  7. Synthesis and structure of two-dimensional transition-metal dichalcogenides

    KAUST Repository

    Shi, Yumeng

    2015-07-13

    Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) exhibit unique electrical, optical, thermal, and mechanical properties, which enable them to be used as building blocks in compact and lightweight integrated electronic systems. The controllable and reliable synthesis of atomically thin TMDCs is essential for their practical application. Recent progress in large-area synthesis of monolayer TMDCs paves the way for practical production of various 2D TMDC layers. The intrinsic optical and electrical properties of monolayer TMDCs can be defined by stoichiometry during synthesis. By manipulating the lattice structure or layer stacking manner, it is possible to create atomically thin van der Waals materials with unique and unexplored physical properties. In this article, we review recent developments in the synthesis of TMDC monolayers, alloys, and heterostructures, which shine light on the design of novel TMDCs with desired functional properties.

  8. Synthesis of reported and revised structures of amathamide D and synthesis of convolutamine F, H and lutamide A, C.

    Science.gov (United States)

    Khan, Faiz Ahmed; Ahmad, Saeed

    2012-03-01

    Total synthesis of the published structure of amathamide D is described. Methyl 2,3,4-tribromo-5-hydroxybenzoate was selected as starting compound because it is readily accessible via acid-mediated Grob fragmentation-aromatization reaction of 1,4,5,6-tetrabromo-7,7-dimethoxybicyclo[2.2.1]hept-5-en-2-one. The aforementioned ester was transformed into the reported structure of amathamide D through methylation of a hydroxyl group and conversion of the ester moiety to a β-aminoethyl side chain. The NMR data of the synthetic compound did not conform to the reported natural product structure possessing contiguously positioned β-aminoethyl side chain, a set of three adjacent bromines, and a methyl ether linkage on the phenyl ring. This prompted us to redefine the natural product structure by synthesizing a product whose spectral data exactly matched with the reported data of amathamide D. The convolutamine H, with completely substituted phenyl ring adorned with an extra methyl ether functional group, has also been synthesized by application of Grob fragmentation-aromatization strategy to 3-(benzyloxy)-1,4,5,6-tetrabromo-7,7-dimethoxybicyclo[2.2.1]hept-5-en-2-one. This approach furnished directly methyl 2,3,4-tribromo-5,6-dimethoxybenzoate, which was converted straightforwardly into convolutamine H. Further, synthesis of convolutamine F and lutamide A and C is also described.

  9. Structural archetypes in nickel(II) hybrid vanadates. Towards a directed hydrothermal synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Luis, R. Fernandez de; Urtiaga, M.K. [Dpto. Mineralogia y Petrologia, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/UPV/EHU, Apdo. 644, 48080 Bilbao (Spain); Mesa, J.L.; Rojo, T. [Dpto. Quimica Inorganica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco UPV/EHU, Apdo. 644, 48080 Bilbao (Spain); Arriortua, M.I. [Dpto. Mineralogia y Petrologia, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/UPV/EHU, Apdo. 644, 48080 Bilbao (Spain)], E-mail: maribel.arriortua@ehu.es

    2009-07-01

    In the present work, we relate the modifications of the initial synthesis parameters (pH value, stoichiometry and concentration) with the different structural archetypes obtained in the {l_brace}Ni/Bpy/VO{r_brace} and {l_brace}Ni/Bpe/VO{r_brace} systems (4,4'-bipyridine (Bpy), 1,2-di(4-pyridyl) ethylene (Bpe)). The vanadium coordination is partially controlled by the hydrothermal synthesis conditions, and the final crystal structures depend on the synergetic interaction between the metal-organic subnets and the vanadium oxide subunits.

  10. Recent developments in quasi-Newton methods for structural analysis and synthesis

    Science.gov (United States)

    Kamat, M. P.; Hayduk, R. J.

    1981-01-01

    Unlike the Newton-Raphson method, quasi-Newton methods by virture of the updates and step length control procedures are globally convergent and hence better suited for the solution of nonlinear problems of structural analysis and synthesis. Extension of quasi-Newton algorithms to large scale problems has led to the development of sparse update algorithms and to economical strategies for evaluating sparse Hessians. Ill-conditioning problems have led to the development of self-scaled variable metric and conjugate gradient algorithms, as well as the use of the singular perturbation theory. This paper emphasizes the effectiveness of such quasi-Newton algorithms for nonlinear structural analysis and synthesis.

  11. Model Updating of Complex Structures Using the Combination of Component Mode Synthesis and Kriging Predictor

    OpenAIRE

    Yang Liu; Yan Li; Dejun Wang; Shaoyi Zhang

    2014-01-01

    Updating the structural model of complex structures is time-consuming due to the large size of the finite element model (FEM). Using conventional methods for these cases is computationally expensive or even impossible. A two-level method, which combined the Kriging predictor and the component mode synthesis (CMS) technique, was proposed to ensure the successful implementing of FEM updating of large-scale structures. In the first level, the CMS was applied to build a reasonable condensed FEM o...

  12. ACCESS 1: Approximation Concepts Code for Efficient Structural Synthesis program documentation and user's guide

    Science.gov (United States)

    Miura, H.; Schmit, L. A., Jr.

    1976-01-01

    The program documentation and user's guide for the ACCESS-1 computer program is presented. ACCESS-1 is a research oriented program which implements a collection of approximation concepts to achieve excellent efficiency in structural synthesis. The finite element method is used for structural analysis and general mathematical programming algorithms are applied in the design optimization procedure. Implementation of the computer program, preparation of input data and basic program structure are described, and three illustrative examples are given.

  13. Synthesis of arborescent model polymer structures by living carbocationic polymerization for structure-property studies

    Science.gov (United States)

    Dos Santos Freire, Lucas

    Polyisobutylene is fully saturated, therefore exhibits outstanding chemical, oxidative and thermal stability,1 which makes it ideally suitable as a model to study mechanical and viscoelastic properties of elastomers, and to correlate properties with structure. The main objective of this dissertation was to develop a fundamental understanding of the mechanism of the synthesis of arborescent (hyperbranched) polyisobutylene (arbPIB) by inimer-type (initiator-monomer) living carbocationic polymerization. The strategy for the effective synthesis of arbPIBs consists of copolymerizing the 4-(2-methoxyisopropyl)styrene (IUPAC name: p-vinylcumyl methyl ether) (IB) via controlled/living carbocationic polymerization using TiCl4 coinitiator. In situ FTIR monitoring showed that the self-condensing vinyl polymerization (SCVP) of MeOIM is possible, and that when copolymerizing MeOIM and IB, a nearly alternating structure and multiple end groups are obtained. arbPIB was synthesized and the repeatability of the polymerization was demonstrated. It was found that higher branching was obtained with increasing [MeOIM] and that branching did not further increase if additional IB was added after the MeOIM had reacted completely. No evident changes were observed when switching solvents from Hx/MeCl to a MeCHx/MeCl mixture. Branching parameters showed that arbPIBs have a behavior between polydisperse stars and polycondensates with the number of branches increasing linearly with molecular weight. Novel arbPIB-based block copolymers (TPEs) were synthesized and it was found that copolymers with low Tg short end blocks and less than 5 mol% of a second monomer exhibit thermoplastic elastomeric properties. The materials were strongly reinforced when compounded with carbon black. arbPIB-b-PS are prospective biomaterials and the establishment of reliable methods for evaluating their short and long term properties is a subject of great importance. A dynamic fatigue testing methodology was developed

  14. Synthesis of computational structures for analog signal processing

    CERN Document Server

    Popa, Cosmin Radu

    2011-01-01

    Presents the most important classes of computational structures for analog signal processing, including differential or multiplier structures, squaring or square-rooting circuits, exponential or Euclidean distance structures and active resistor circuitsIntroduces the original concept of the multifunctional circuit, an active structure that is able to implement, starting from the same circuit core, a multitude of continuous mathematical functionsCovers mathematical analysis, design and implementation of a multitude of function generator structures

  15. Synthesis and Image Matching On Structural Patterns Using Affine Transformation

    Directory of Open Access Journals (Sweden)

    S.Vandana

    2012-06-01

    Full Text Available This paper focuses in explaining a Fourier based affine estimator which is applied to the task of Image Synthesis. An affine transformation is an important class of linear 2-D geometric transformations which maps variables into new by applying a linear combination of translation, rotation, scaling and/or shearing operations. Conventional retrieval systems are very effective when knowledge information and query information are in a uniform orientation but fails in recognition when effects such as scaling, orientation exist. But as this technique is based on texture analysis, which is termed the affine estimator, it will even match the images with non-uniform orientation.

  16. Synthesis of Ge-imogolite: influence of the hydrolysis ratio on the structure of the nanotubes.

    Science.gov (United States)

    Levard, C; Masion, A; Rose, J; Doelsch, E; Borschneck, D; Olivi, L; Chaurand, P; Dominici, C; Ziarelli, F; Thill, A; Maillet, P; Bottero, J Y

    2011-08-28

    The synthesis protocol for Ge-imogolite (aluminogermanate nanotubes) consists of 3 main steps: base hydrolysis of a solution of aluminum and germanium monomers, stabilization of the suspension and heating at 95 °C. The successful synthesis of these nanotubes was found to be sensitive to the hydrolysis step. The impact of the hydrolysis ratio (from n(OH)/n(Al) = 0.5 to 3) on the final product structure was examined using a combination of characterization tools. Thus, key hydrolysis ratios were identified: n(OH)/n(Al) = 1.5 for the formation of nanotubes with structural defects, n(OH)/n(Al) = 2 for the synthesis of a well crystallized Ge imogolite and n(OH)/n(Al) > 2.5 where nanotube formation is hindered. The capability of controlling the degree of the nanotube's crystallinity opens up interesting opportunities in regard to new potential applications.

  17. Minute-made and low carbon fingerprint microwave synthesis of high quality templated mesoporous silica

    KAUST Repository

    Chaignon, J.

    2015-01-01

    © The Royal Society of Chemistry 2015. Hexagonal mesostructured templated silicas were produced in less than 10 minutes using an ultra-fast microwave assisted hydrothermal synthesis. Typically, 10 g can be prepared at once in a commercial microwave device usually devoted to analytical digestion. Undesired alcohol side-products were avoided using inexpensive water colloidal silica instead of silicon alkoxides as the silicon source. In comparison with classical heating activation, the absence of pore expansion and pore wall thickening even for synthesis temperatures as high as 190 °C evidenced that heat transfer and diffusion of matter had no time to take place. Comparison between the chemically extracted and calcined samples shows that the structure was better stabilized for autoclaving above 150 °C. However, a fast temperature ramping and final temperatures above 180 °C were required to sear structures of the highest quality comparable to that of the best conventional methods. This is rationalized by assuming a sequential flake-by-flake assembly of the pore-wall at the micelle palisade. Notably, tosylate counterions yielded better structural characteristics than bromide counterions and allowed better opportunities for surfactant recycling.

  18. Total Synthesis and Structure-Activity Relationship of Glycoglycerolipids from Marine Organisms

    Directory of Open Access Journals (Sweden)

    Jun Zhang

    2014-06-01

    Full Text Available Glycoglycerolipids occur widely in natural products, especially in the marine species. Glycoglycerolipids have been shown to possess a variety of bioactivities. This paper will review the different methodologies and strategies for the synthesis of biological glycoglycerolipids and their analogs for bioactivity assay. In addition, the bioactivities and structure-activity relationship of the glycoglycerolipids are also briefly outlined.

  19. Synthesis and crystal structure of a cyano-substituted oligo(p-phenylenevinylene)

    NARCIS (Netherlands)

    Gill, RE; vanHutten, PF; Meetsma, A; Hadziioannou, G

    1996-01-01

    Described is the synthesis and the single-crystal structure of an all-trans dicyano-substituted five-ring PPV oligomer having two 12-octyloxy side chains attached onto the central phenyl ring. The crystal density (D-calc = 1.210 g cm(-3)) appears to be almost 10% higher than that of the crystalline

  20. 2-(hydroxymethyl)aspartic acid: synthesis, crystal structure, and reaction with a transaminase

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, J.J.; Metzler, D.E.; Powell, D.; Jacobson, R.A.

    1980-11-05

    The synthesis and x-ray crystal structure of 2-(hydroxymethyl) aspartic acid and the preliminary evaluation of its interaction with cytosolic aspartate aminotransferase of pig heart are described. A dissociation constant 1.4 mM for the L-2-(hydroxymethyl) aspartate complex with the enzyme was obtained. 2 figures. (DP)

  1. Effect on nerve structures of functionalized gold-chitosan nanoparticles obtained by one pot synthesis

    Directory of Open Access Journals (Sweden)

    Marius Dobromir

    2011-02-01

    Full Text Available Gold nanoparticles have potential applications in drug delivery, cancer diagnosis and therapy, food industry and environment remediation. However, little is known about their potential toxicity or fate in the environment. In this study we observed significant effects of functionalized gold-chitosan nanoparticles obtained by one pot synthesis on nerve structures of Wistar rats.

  2. Aircraft interior noise prediction using a structural-acoustic analogy in NASTRAN modal synthesis

    Science.gov (United States)

    Grosveld, Ferdinand W.; Sullivan, Brenda M.; Marulo, Francesco

    1988-01-01

    The noise induced inside a cylindrical fuselage model by shaker excitation is investigated theoretically and experimentally. The NASTRAN modal-synthesis program is used in the theoretical analysis, and the predictions are compared with experimental measurements in extensive graphs. Good general agreement is obtained, but the need for further refinements to account for acoustic-cavity damping and structural-acoustic interaction is indicated.

  3. Synthesis and structural characterization of manganese olivine lithium phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Herrera Robles, Joel O. [Basic Science Department, IIT, Universidad Autónoma de Ciudad Juárez, Av. del Charro 460 norte Cd. Juárez, Chih. C.P. 32310 (Mexico); Fuentes Cobas, Luis E. [Centro de Investigación en Materiales Avanzados CIMAV, Complejo Industrial, M. Cervantes 120, Chihuahua C.P. 31109 (Mexico); Díaz de la Torre, Sebastián [Instituto Politécnico Nacional, Centro de Investigación e Innovación Tecnológica CIITEC, Azcapotzalco, México, D.F. C.P. 02250 (Mexico); Camacho Montes, Héctor, E-mail: hcamacho@uacj.mx [Basic Science Department, IIT, Universidad Autónoma de Ciudad Juárez, Av. del Charro 460 norte Cd. Juárez, Chih. C.P. 32310 (Mexico); Elizalde Galindo, José T.; García Casillas, Perla E.; Rodríguez González, Claudia A. [Basic Science Department, IIT, Universidad Autónoma de Ciudad Juárez, Av. del Charro 460 norte Cd. Juárez, Chih. C.P. 32310 (Mexico); Álvarez Contreras, Lorena [Centro de Investigación en Materiales Avanzados CIMAV, Complejo Industrial, M. Cervantes 120, Chihuahua C.P. 31109 (Mexico)

    2015-09-15

    Highlights: • LiMnPO{sub 4} was obtained by sol gel method and crystallization in reducing atmosphere. • Magnetic and electric properties are reported for LiMnPO{sub 4}. • Electrochemical properties are also found and enhanced by adding carbon. • SEM and HRTEM show the submicron powder nature. • The multifunctional behavior of LiMnPO{sub 4} is experimentally demonstrated. - Abstract: The manganese olivine lithium phosphate is a multifunctional material. If carbon is added to form a composite LiMnPO{sub 4}–C, electrochemical properties can be enhanced, making this material a good candidate for battery cathode. High magnetic susceptibility is reported for this compound at room temperature. In this work, the magnetic response was measured through a Field Cooling/Zero Field Cooling technique at temperature below 100 K. Weak ferroelectric properties at room temperature were measured. Even though, the promising applications and the interesting properties of this system, the attention received in the literature is relatively low. The synthesis of this material is difficult because of the rapid manganese oxidation and the need of a reducing atmosphere. In fact, only few authors report the synthesis of the pure phase. In the present work, nanostructured LiMnPO{sub 4} is obtained by sol gel chemical method and according to X-ray diffraction patterns, pure LiMnPO{sub 4} is obtained after calcination in a reducing atmosphere (10% H{sub 2} – 90% Ar). Nanostructured LiMnPO{sub 4} is a material with very interesting properties that deserves attentions.

  4. Synthesis and structural characterization of manganese olivine lithium phosphate

    International Nuclear Information System (INIS)

    Highlights: • LiMnPO4 was obtained by sol gel method and crystallization in reducing atmosphere. • Magnetic and electric properties are reported for LiMnPO4. • Electrochemical properties are also found and enhanced by adding carbon. • SEM and HRTEM show the submicron powder nature. • The multifunctional behavior of LiMnPO4 is experimentally demonstrated. - Abstract: The manganese olivine lithium phosphate is a multifunctional material. If carbon is added to form a composite LiMnPO4–C, electrochemical properties can be enhanced, making this material a good candidate for battery cathode. High magnetic susceptibility is reported for this compound at room temperature. In this work, the magnetic response was measured through a Field Cooling/Zero Field Cooling technique at temperature below 100 K. Weak ferroelectric properties at room temperature were measured. Even though, the promising applications and the interesting properties of this system, the attention received in the literature is relatively low. The synthesis of this material is difficult because of the rapid manganese oxidation and the need of a reducing atmosphere. In fact, only few authors report the synthesis of the pure phase. In the present work, nanostructured LiMnPO4 is obtained by sol gel chemical method and according to X-ray diffraction patterns, pure LiMnPO4 is obtained after calcination in a reducing atmosphere (10% H2 – 90% Ar). Nanostructured LiMnPO4 is a material with very interesting properties that deserves attentions

  5. Stop Flow Lithography Synthesis and Characterization of Structured Microparticles

    Directory of Open Access Journals (Sweden)

    David Baah

    2014-01-01

    Full Text Available In this study, the synthesis of nonspherical composite particles of poly(ethylene glycol diacrylate (PEG-DA/SiO2 and PEG-DA/Al2O3 with single or multiple vias and the corresponding inorganic particles of SiO2 and Al2O3 synthesized using the Stop Flow Lithography (SFL method is reported. Precursor suspensions of PEG-DA, 2-hydroxy-2-methylpropiophenone, and SiO2 or Al2O3 nanoparticles were prepared. The precursor suspension flows through a microfluidic device mounted on an upright microscope and is polymerized in an automated process. A patterned photomask with transparent geometric features masks UV light to synthesize the particles. Composite particles with vias were synthesized and corresponding inorganic SiO2 and Al2O3 particles were obtained through polymer burn-off and sintering of the composites. The synthesis of porous inorganic particles of SiO2 and Al2O3 with vias and overall dimensions in the range of ~35–90 µm was achieved. BET specific surface area measurements for single via inorganic particles were 56–69 m2/g for SiO2 particles and 73–81 m2/g for Al2O3 particles. Surface areas as high as 114 m2/g were measured for multivia cubic SiO2 particles. The findings suggest that, with optimization, the particles should have applications in areas where high surface area is important such as catalysis and sieving.

  6. Synthesis, structure, and frequency-doubling effect of calcium cyanurate.

    Science.gov (United States)

    Kalmutzki, Markus; Ströbele, Markus; Wackenhut, Frank; Meixner, Alfred J; Meyer, H-Jürgen

    2014-12-15

    Calcium cyanurate is synthesized by reacting calcium chloride with potassium cyanate following a solid-state reaction. The formation of the new compound Ca3(O3C3N3)2 (CCY), which occurs by the cyclotrimerization of cyanate ions, was examined thermoanalytically and the crystal structure was determined by single-crystal structure analysis. The structure of CCY is closely related to the structure of the well-known oxoborate β-BaB2O4 (BBO). Second harmonic generation (SHG) measurements on crystal powders show a higher SHG efficiency for CCY than for BBO by about one order of magnitude.

  7. Synthesis, structure, and frequency-doubling effect of calcium cyanurate.

    Science.gov (United States)

    Kalmutzki, Markus; Ströbele, Markus; Wackenhut, Frank; Meixner, Alfred J; Meyer, H-Jürgen

    2014-12-15

    Calcium cyanurate is synthesized by reacting calcium chloride with potassium cyanate following a solid-state reaction. The formation of the new compound Ca3(O3C3N3)2 (CCY), which occurs by the cyclotrimerization of cyanate ions, was examined thermoanalytically and the crystal structure was determined by single-crystal structure analysis. The structure of CCY is closely related to the structure of the well-known oxoborate β-BaB2O4 (BBO). Second harmonic generation (SHG) measurements on crystal powders show a higher SHG efficiency for CCY than for BBO by about one order of magnitude. PMID:25345390

  8. Origami-inspired active structures: a synthesis and review

    Science.gov (United States)

    Peraza-Hernandez, Edwin A.; Hartl, Darren J.; Malak, Richard J., Jr.; Lagoudas, Dimitris C.

    2014-09-01

    Origami, the ancient art of paper folding, has inspired the design of engineering devices and structures for decades. The underlying principles of origami are very general, which has led to applications ranging from cardboard containers to deployable space structures. More recently, researchers have become interested in the use of active materials (i.e., those that convert various forms of energy into mechanical work) to effect the desired folding behavior. When used in a suitable geometry, active materials allow engineers to create self-folding structures. Such structures are capable of performing folding and/or unfolding operations without being kinematically manipulated by external forces or moments. This is advantageous for many applications including space systems, underwater robotics, small scale devices, and self-assembling systems. This article is a survey and analysis of prior work on active self-folding structures as well as methods and tools available for the design of folding structures in general and self-folding structures in particular. The goal is to provide researchers and practitioners with a systematic view of the state-of-the-art in this important and evolving area. Unifying structural principles for active self-folding structures are identified and used as a basis for a quantitative and qualitative comparison of numerous classes of active materials. Design considerations specific to folded structures are examined, including the issues of crease pattern identification and fold kinematics. Although few tools have been created with active materials in mind, many of them are useful in the overall design process for active self-folding structures. Finally, the article concludes with a discussion of open questions for the field of origami-inspired engineering.

  9. Synthesis and Crystal Structure of a Novel Calix [8] arene Ester Derivative

    Institute of Scientific and Technical Information of China (English)

    DaQiangYUAN; RuJiWANG; 等

    2002-01-01

    The synthesis and crystal structure of a novel calix[8] arene ester are reported herein. The calix [8] arene ester derivative has been characterized by IR,NMR and X-ray crystal analysis. The X-ray structure analysis revealed that the 8 phenolic hydroxy groups of the calix [8] arene have been substituted by 4 diethyl dibromomalonate molecules with each two adjacent hydroxy oxygen atoms attached to a bridge diethyl malonate.

  10. Polyrhythmic Tapping: Examining the Effectiveness of the Strategy of Organizing Rhythmic Structures through Synthesis

    Science.gov (United States)

    Yokus, Hamit; Yokus, Tuba

    2015-01-01

    In this study the strategy of organizing rhythmic structures through synthesis is named, and defined, and its procedures are described. Its effectiveness for teaching the execution of 3:2, 4:3, 8:3, 5:4, and 3:5 polyrhythmic structures is examined and described. Pre-test and Post-test Control Group Design was employed to test the effectiveness of…

  11. Synthesis and Structure of Dimeric β-Diketiminato Co(Ⅱ) Chloride Complex

    Institute of Scientific and Technical Information of China (English)

    GAO Wei; MU Ying; LI Guang-hua; LIU Xiao-ming; SU Qing; YAO Wei

    2005-01-01

    @@ Introduction Recently, late-transition-metal complexes have been extensively used as both inorganic and organometallic catalysts[1]. Some complexes have been developed as the novel olefin polymerization catalysts[2-4] and copolymerization catalysts for ethylene and polar comonomers[5] due to their lower oxophilicity and presumed greater functional tolerance. Moreover, compounds with imine ligands have received more attention and have been reported for the synthesis method, structure, mechanism and application[6-9]. In this contribution, we report the synthesis of the dimericβ-diketiminato Co(Ⅱ)chloride complex:

  12. Various double component mode synthesis and sub-structuring methods for dynamic mixed FEM

    OpenAIRE

    Garambois, Pierre; Besset, Sébastien; Jézéquel, Louis

    2015-01-01

    International audience Mixed Finite Element Model Component Mode Synthesis (CMS) a b s t r a c t This paper presents various sub-structuring and component mode synthesis (CMS) reduction methods for dynamic mixed displacement-stress FEM. The idea is to imagine a new way of reducing a mixed FEM, by splitting the reduction of the displacement and the stress parameters and adapting primal existing modal reduction methods to each field of the mixed model. In this way, we can choose, for each su...

  13. The Use of Original Structure-Directing Agents for the Synthesis of EMC-1 Zeolite

    Directory of Open Access Journals (Sweden)

    Daou T.J.

    2015-03-01

    Full Text Available By using a steric approach, it is possible to design templates matching closely with an inorganic framework. Herein, the design, synthesis and successful application of several di(azacrown ether templates to direct the formation of EMC-1 zeolite (FAU-type are reported. Following a high throughput experiment design, the synthesis gel composition was optimized to obtain well-crystallized materials. Taking into account their respective crystallization rates, their textural and morphological properties were comparable to their counterparts, typically structured by 15-crown-5 ether.

  14. STRUCTURE SYNTHESIS OF 4-DOF PARALLEL ROBOT MECHANISMS BASED ON SCREW THEORY

    Institute of Scientific and Technical Information of China (English)

    Fang Hairong; Fang Yuefa; Guo Sheng

    2004-01-01

    Structural synthesis for 4-DOF parallel manipulators using screw theory is systematically studied. Motion properties and constraint conditions of 4-DOF parallel manipulators according to the relationship between screw and reciprocal screw are analyzed. Mathematical expressions for constraint screws and twist screws of moving platform are constructed, and all possible limbs, which provide one or more force constraints, are enumerated. Finally, a parallel manipulator with 3-rotation-DOF and 1-translation-DOF is used as an example to describe the synthesis procedure for symmetrical and non-symmetrical 4-DOF parallel manipulators.

  15. Electrochemical synthesis and crystal structure of ordered arrays of Со – nanotubes

    Directory of Open Access Journals (Sweden)

    Artem Kozlovskiy

    2015-09-01

    Full Text Available In this paper, using the method of electrochemical template synthesis, ordered arrays of metallic nanostructures on the basis of cobalt with various dimensions (180-380 nm were obtained. The diameter of Co-nanotubes was controlled by original polymer matrix, which provided to prepare arrays consisting of individually standing cobalt nanotubes. The crystal structure of the synthesized samples was studied by X-ray diffraction to determine cell parameters and crystallite size. Decrease of the conductive properties of Co - nanotubes can be explained by inhomogeneity of the crystallites formed during synthesis, because the growth rate of nanostructures directly affects the size of the crystallites.

  16. Reduced models of multi-stage cyclic structures using cyclic symmetry reduction and component mode synthesis

    Science.gov (United States)

    Tran, Duc-Minh

    2014-10-01

    Reduced models of multi-stage cyclic structures such as bladed-disk assemblies are developed by using the multi-stage cyclic symmetry reduction and/or component mode synthesis methods. The multi-stage cyclic symmetry reduction consists in writing the equations of the bladed disks, the inter-disk structures, the inter-disk constraints and the whole multi-stage coupled system in terms of the traveling wave coordinates for all the phase indexes of the reference sectors and for all the bladed disks. Several reduced coupled systems are then solved by selecting at each time only one or a few phase indexes for each bladed disk and by applying the cyclic symmetry boundary conditions. On the other hand, component mode synthesis methods are used either independently or in combination with the multi-stage cyclic symmetry reduction to obtain reduced models of the multi-stage structure. Two of them are particularly efficient, that are firstly component mode synthesis methods with interface modes applied on the bladed disks and secondly component mode synthesis methods with traveling wave coordinates applied on the reference sectors.

  17. Optical and electrochemical properties of CeO{sub 2} thin film prepared by an alkoxide route

    Energy Technology Data Exchange (ETDEWEB)

    Avellaneda, Cesar O. [Departamento de Quimica - LIEC, Universidade Federal de Sao Carlos, C.P. 676, CEP 13565-905, Sao Carlos, SP (Brazil); Berton, Marcos A.C. [Departamento de Tecnologia de Materiais, Instituto de Tecnologia para o Desenvolvimento - LACTEC, C.P. 19067, CEP 81531-990, Curitiba, PR (Brazil); Bulhoes, Luis O.S. [Departamento de Quimica - LIEC, Universidade Federal de Sao Carlos, C.P. 676, CEP 13565-905, Sao Carlos, SP (Brazil); CENIP, Centro Universitario Central Paulista - UNICEP, Rua Miguel Petroni 5111, CEP 13563-470, Sao Carlos, SP (Brazil)

    2008-02-15

    Transparent CeO{sub 2} thin solid films, used as ion storage layer in electrochromic devices were prepared by the sol-gel method using an alkoxide route combined with the dip-coating technique. The precursor sol was prepared from a mixture of cerium (IV) methoxyethoxide in anhydrous 2-butanol. Electrochemical Li{sup +} intercalation/deintercalation was performed by cyclic voltammetry and the results indicate that the CeO{sub 2}/LiClO{sub 4} system is electrochemically reversible. The total inserted/extracted charge of the CeO{sub 2} film was determined by chronoamperometric measurements, which showed an ion storage capacity of {proportional_to}14 mC/cm{sup 2}. The solid-state diffusion of lithium ion into the CeO{sub 2} thin films was investigated by electrochemical impedance spectroscopy. (author)

  18. Fabrication and performances of MWCNT/TiO2 composites derived from MWCNTs and titanium (IV) alkoxide precursors

    Indian Academy of Sciences (India)

    Mingliang Chen; Fengjun Zhang; Wonchun Oh

    2011-07-01

    Multi-walled carbon nanotubes (MWCNTs)/TiO2 composites were synthesized by sol–gel technique using titanium (IV) -butoxide (TNB), titanium (IV) isopropoxide (TIP) and titanium (IV) propoxide (TPP) as different titanium alkoxide precursors. The as-prepared composites were comprehensively characterized by BET surface area, SEM, XRD, EDX and UV-Vis absorption spectroscopy. The samples were evaluated for their photocatalytic activity towards the degradation of methylene blue (MB) under UV irradiation. The results indicated that the sample MPB had best excellent photocatalytic activity among the three kinds of samples. Furthermore, we also used piggery waste to determine the photocatalytic activity for the MWCNT/TiO2 composites by using a chemical oxygen demand (COD) method. It seemed all of the samples have an excellent removal effect of COD. From the results of the bactericidal test, MWCNT/TiO2 composites with sunlight had a greater effect on E. coli than any other experimental conditions.

  19. Synthesis and peculiarities of the cesium zeolite crystal structure (cesite)

    International Nuclear Information System (INIS)

    An attempt is made to synthesize cesium zeolite by introduction of amorphous seed crystals which correspond by composition with cesium-containing zeolite into the aluminosilicate gel, since this method can produce zeolite with a crystal structure it would not adopt under the usual conditions. It is seen that during crystablization upon introduction of a seed crystal the cesium content in zeolite decreases. A more complete structural elucidation of zeolite obtained by the suggested method was carried out by x0ray and IR spectral analyses. The data of x-ray analysis showed that the structures of synthesized zeolite and binary octagonal pores are similar

  20. Structural diversity and chemical synthesis of peroxide and peroxide-derived polyketide metabolites from marine sponges.

    Science.gov (United States)

    Norris, Matthew D; Perkins, Michael V

    2016-07-28

    Covering: up to early 2016Marine sponges are widely known as a rich source of natural products, especially of polyketide origin, with a wealth of chemical diversity. Within this vast collection, peroxide and peroxide-derived secondary metabolites have attracted significant interest in the fields of natural product isolation and chemical synthesis for their structural distinction and promising in vitro antimicrobial and anticancer properties. In this review, peroxide and peroxide-derived polyketide metabolites isolated from marine sponges in the past 35 years are summarised. Efforts toward their synthesis are detailed with a focus on methods that utilise or attempt to elucidate the complex biosynthetic interrelationships of these compounds beyond enzymatic polyketide synthesis. Recent isolations, advances in synthetic methodology and theories of biogenesis are highlighted and critically evaluated. PMID:27163115

  1. Preparation of epoxy/zirconia hybrid materials via in situ polymerization using zirconium alkoxide coordinated with acid anhydride

    International Nuclear Information System (INIS)

    Highlights: → Novel epoxy/zirconia hybrid materials were synthesized via in situ polymerization using zirconium alkoxide coordinated with acid anhydride. → The half-ester compound of acid anhydride desorbed from zirconium played as curing agent of epoxy resin. → The zirconia was uniformly dispersed in the epoxy matrix on the nanometer or sub-nanometer scale by synchronizing the epoxy curing and sol-gel reactions. → The refractive indices of the hybrid materials significantly improved with an increase in the zirconia content. - Abstract: Novel epoxy/zirconia hybrid materials were synthesized using a bisphenol A epoxy resin (diglycidyl ether of bisphenol A; DGEBA), zirconium(IV)-n-propoxide (ZTNP), and hexahydrophthalic anhydride (HHPA) via in situ polymerization. HHPA played two roles in this system: it acted as a modifier to control the hydrolysis and condensation reactions of zirconium alkoxide and also as a curing agent - the half-ester compound of HHPA desorbed from zirconium reacted with the epoxy resin to form the epoxy network. As a result, both the sol-gel reaction and epoxy curing occurred simultaneously in a homogeneous solution, and organic-inorganic hybrid materials were readily obtained. Further, the zirconia produced by the in situ polymerization was uniformly dispersed in the epoxy matrix on the nanometer or sub-nanometer scale; thus, hybrid materials that exhibited excellent optical transparency were obtained. Furthermore, the heat resistance of the hybrid materials could be improved by hybridization with zirconia. And, the refractive indices of the hybrid materials significantly improved with an increase in the zirconia content.

  2. Preparation of epoxy/zirconia hybrid materials via in situ polymerization using zirconium alkoxide coordinated with acid anhydride

    Energy Technology Data Exchange (ETDEWEB)

    Ochi, Mitsukazu, E-mail: mochi@ipcku.kansai-u.ac.jp [Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Suita-shi, Osaka 564-8680 (Japan); Nii, Daisuke; Harada, Miyuki [Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Suita-shi, Osaka 564-8680 (Japan)

    2011-09-15

    Highlights: {yields} Novel epoxy/zirconia hybrid materials were synthesized via in situ polymerization using zirconium alkoxide coordinated with acid anhydride. {yields} The half-ester compound of acid anhydride desorbed from zirconium played as curing agent of epoxy resin. {yields} The zirconia was uniformly dispersed in the epoxy matrix on the nanometer or sub-nanometer scale by synchronizing the epoxy curing and sol-gel reactions. {yields} The refractive indices of the hybrid materials significantly improved with an increase in the zirconia content. - Abstract: Novel epoxy/zirconia hybrid materials were synthesized using a bisphenol A epoxy resin (diglycidyl ether of bisphenol A; DGEBA), zirconium(IV)-n-propoxide (ZTNP), and hexahydrophthalic anhydride (HHPA) via in situ polymerization. HHPA played two roles in this system: it acted as a modifier to control the hydrolysis and condensation reactions of zirconium alkoxide and also as a curing agent - the half-ester compound of HHPA desorbed from zirconium reacted with the epoxy resin to form the epoxy network. As a result, both the sol-gel reaction and epoxy curing occurred simultaneously in a homogeneous solution, and organic-inorganic hybrid materials were readily obtained. Further, the zirconia produced by the in situ polymerization was uniformly dispersed in the epoxy matrix on the nanometer or sub-nanometer scale; thus, hybrid materials that exhibited excellent optical transparency were obtained. Furthermore, the heat resistance of the hybrid materials could be improved by hybridization with zirconia. And, the refractive indices of the hybrid materials significantly improved with an increase in the zirconia content.

  3. Synthesis and Antifungal Activity of Musa Phytoalexins and Structural Analogs

    OpenAIRE

    Adriana Gallego; Gloria Cardona; Victor Arango; Yoni Rosero; Fernando Torres; Fernando Echeverri; Gustavo Escobar; Winston Quiñones

    2000-01-01

    Several perinaphthenone/phenylphenalenone compounds were synthesized to establish a relationship between structure and antifungal activity against Mycosphaerella fijiensis. Substitutions on the unsaturated carbonyl system or addition of a phenyl group reduced antibiotic activity.

  4. Synthesis and Antifungal Activity of Musa Phytoalexins and Structural Analogs

    Directory of Open Access Journals (Sweden)

    Adriana Gallego

    2000-07-01

    Full Text Available Several perinaphthenone/phenylphenalenone compounds were synthesized to establish a relationship between structure and antifungal activity against Mycosphaerella fijiensis. Substitutions on the unsaturated carbonyl system or addition of a phenyl group reduced antibiotic activity.

  5. Synthesis, Characterization and Pore Structure Analysis of Mesoporous Materials

    OpenAIRE

    Saldarriaga Lopez, Laura Carolina

    2014-01-01

    Self-assembly provides a route to make mesoporous structures that have accessible internal surface area. These types of materials show promise for use in opto-electronic devices as well as for energy storage devices. In this work we synthesize a range of mesoporous thin films from molecular and nanocrystal precursors. We characterize these films' porous structure and surface area using ellipsometric-porosimetry. This work is divided into three parts; the first section focuses on synthesizing ...

  6. Survey of marine natural product structure revisions: a synergy of spectroscopy and chemical synthesis.

    Science.gov (United States)

    Suyama, Takashi L; Gerwick, William H; McPhail, Kerry L

    2011-11-15

    The structural assignment of new natural product molecules supports research in a multitude of disciplines that may lead to new therapeutic agents and or new understanding of disease biology. However, reports of numerous structural revisions, even of recently elucidated natural products, inspired the present survey of techniques used in structural misassignments and subsequent revisions in the context of constitutional or configurational errors. Given the comparatively recent development of marine natural products chemistry, coincident with modern spectroscopy, it is of interest to consider the relative roles of spectroscopy and chemical synthesis in the structure elucidation and revision of those marine natural products that were initially misassigned. Thus, a tabulated review of all marine natural product structural revisions from 2005 to 2010 is organized according to structural motif revised. Misassignments of constitution are more frequent than perhaps anticipated by reliance on HMBC and other advanced NMR experiments, especially when considering the full complement of all natural products. However, these techniques also feature prominently in structural revisions, specifically of marine natural products. Nevertheless, as is the case for revision of relative and absolute configuration, total synthesis is a proven partner for marine, as well as terrestrial, natural products structure elucidation. It also becomes apparent that considerable 'detective work' remains in structure elucidation, in spite of the spectacular advances in spectroscopic techniques.

  7. Stereoselectively synthesis and structural confirmation of dehydrodipeptides with dehydrobutyrine.

    Science.gov (United States)

    Tian, Xia; Li, Linna; Han, Jianrong; Zhen, Xiaoli; Liu, Shouxin

    2016-01-01

    Most of polypeptides containing α,β-dehydroamino acids have important biological activity, so exploration of synthetic method has practical significance. In this paper, dipeptides were prepared from l-threonine by protecting of c-terminal allyl acetate, and condensing reaction with a series of N-Boc amino acid. Then, treatment of dipeptides obtained with DMAP, (Boc)2O and tetramethylguanidine in the acetonitrile occured β-elimination reaction to yield stereoselectively dehydrodipeptides. Structures of dehydrodipeptides were confirmed by (1)H NMR, (13)C NMR and MS. Analysis of (1)H NMR, 2D NMR and crystal structure showed that the dehydrodipeptides were Z-configuration.Graphical abstractDehydrodipeptides were prepared from l-threonine. Their structures were confirmed by (1)H NMR, (13)C NMR and MS. PMID:27047726

  8. Total Synthesis and Structural Revision of the Cytotoxin Aruncin B.

    Science.gov (United States)

    Ribaucourt, Aubert; Hodgson, David M

    2016-09-01

    The sodium salts E-15 and Z-15 of the originally proposed dihydropyran acid structure of aruncin B (1) were prepared through ring-closing alkene metathesis (RCM) and ethoxyselenation-selenoxide elimination, but acid sensitivity of these salts, together with inconsistencies in the spectral data, suggested a significant structural misassignment. A β-iodo Morita-Baylis-Hillman reaction to give Z-iodo ester 24, followed by Sonogashira cross-coupling-5-exo-dig lactonization, provided concise access to a Z-γ-alkylidenebutenolide 18, which possessed data corresponding to those originally reported for aruncin B. PMID:27529438

  9. Synthesis and Crystal Structure of Metronidazole-derived Compound

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A MET-OH derivative, MET-OTs 1, was designed, prepared and structurally charac- terized by single-crystal X-ray diffraction. X-ray structure analysis reveals that 1 crystallizes in the monoclinic system, space group P21/c, with a = 16.1178(14), b = 7.5473(6), c = 13.4161(11) (A), V = 1520.3(2) (A)3, β = 111.3210(10)o, Z = 4, Dc = 1.421 g/cm3 and F(000) = 680.

  10. Synthesis, crystal structure and biological activity of novel diester cyclophanes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Pengfei; Yang, Bingqin; Fang, Xianwen; Cheng, Zhao; Yang, Meipan, E-mail: yangbq@nwu.edu.cn [Department of Chemistry, Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Northwest University, Shaanxi (China)

    2012-10-15

    A series of novel diester cyclophanes was synthesized by esterification of 1,2-benzenedicarbonyl chloride with eight different diols under high dilution conditions. The structures of the compounds were verified by elemental analysis, {sup 1}H nuclear magnetic resonance (NMR), IR spectroscopy and high resolution mass spectrometry (HRMS). The crystal structures of two compounds were characterized by single crystal X-ray diffractometry (XRD). All the new cyclophanes were evaluated for biological activities and the results showed that some of these compounds have low antibacterial or antifungal activities (author)

  11. Apatite-structured compounds: Synthesis and high-temperature investigation

    Energy Technology Data Exchange (ETDEWEB)

    Knyazev, Alexander V.; Chernorukov, Nikolai G. [Nizhny Novgorod State University, Gagarin Prospekt 23/2, 603950 Nizhny Novgorod (Russian Federation); Bulanov, Evgeny N., E-mail: bulanoven@yandex.ru [Nizhny Novgorod State University, Gagarin Prospekt 23/2, 603950 Nizhny Novgorod (Russian Federation)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer 25 Apatite-structured compounds of different composition were synthesized. Black-Right-Pointing-Pointer Phase transformations of them in wide temperature interval were investigated. Black-Right-Pointing-Pointer For the first time polymorphic transitions were observed on 6 apatites. Black-Right-Pointing-Pointer Thermal expansion coefficients of all studied phases were calculated. Black-Right-Pointing-Pointer The direct communication between thermal stability and expansion anisotropy was observed. - Abstract: The phase transitions and thermal expansion of apatite-structured compounds with the general formula M{sup II}{sub 5}(A{sup V}O{sub 4}){sub 3}L (M{sup II} = Ca, Sr, Cd, Ba, Pb; A{sup V} = P, V, Cr, Mn; L = OH, F, Cl, Br, I) have been studied by high-temperature X-ray diffraction and differential thermal analysis. Polymorphic transition nature was explained on the basis of the structure data. Connection between thermal stability and peculiarities of thermal expansion, which were explained in assumption of composition and structure of apatites was ascertained.

  12. Synthesis, spectral and structural properties of bis-imidazoline selones

    Indian Academy of Sciences (India)

    Arruri Sathyanarayana; Katam Srinivas; Anindita Mandal; Saswati Gharami; Ganesan Prabusankar

    2014-09-01

    New biphenyl derivatives of bis-imidazoline selones were synthesized in good yield and characterized by multinuclear (1D and 2D) NMR and UV-vis studies. The solid state structures of bis-imidazoline selones were further confirmed by single crystal X ray diffraction technique.

  13. Low-authority control synthesis for large space structures

    Science.gov (United States)

    Aubrun, J. N.; Margulies, G.

    1982-01-01

    The control of vibrations of large space structures by distributed sensors and actuators is studied. A procedure is developed for calculating the feedback loop gains required to achieve specified amounts of damping. For moderate damping (Low Authority Control) the procedure is purely algebraic, but it can be applied iteratively when larger amounts of damping are required and is generalized for arbitrary time invariant systems.

  14. Synthesis and Crystal Structures of Schiff Bases Bearing Ferrocenylphenyl Groups

    Institute of Scientific and Technical Information of China (English)

    Yan XU; Yong FU; Mao Ping SONG; Yang Jie WU

    2005-01-01

    The Schiff bases bearing ferrocenylphenyl and diferrocenylphenyl groups were synthesized by the reactions of m-ferrocenylaniline with salicylaldehyde or 1, 4-bis (2'-formylphenyl)-1, 4-dioxabutane. The title compounds were characterized by elemental analysis, IR, 1H NMR and X-ray structural determination.

  15. Synthesis and structure determination of novel hexasubstituted cyclohexadienes

    Institute of Scientific and Technical Information of China (English)

    Hong Mei Qu; Xin Hui Niu; Juan Li; Jun Liu; Li Li Jiang; Jian Ke Tang; Li Shan Zhou

    2012-01-01

    The linear trienes were obtained in high yields by copper-mediated cycloaddition of 2,5-bis(trimethylsilyl)zirconacyclopentadienes with dimethyl acetylenedicarboxylate (DMAD) which can be quantitatively converted to novel asymmetric hexasubstituted cyclohexadienes with high (E)-stereoselectivity.The structure of cyclohexadienes was determined via X-ray analysis.

  16. Self-assembled SnO2 micro- and nanosphere-based gas sensor thick films from an alkoxide-derived high purity aqueous colloid precursor.

    Science.gov (United States)

    Kelp, G; Tätte, T; Pikker, S; Mändar, H; Rozhin, A G; Rauwel, P; Vanetsev, A S; Gerst, A; Merisalu, M; Mäeorg, U; Natali, M; Persson, I; Kessler, V G

    2016-04-01

    Tin oxide is considered to be one of the most promising semiconductor oxide materials for use as a gas sensor. However, a simple route for the controllable build-up of nanostructured, sufficiently pure and hierarchical SnO2 structures for gas sensor applications is still a challenge. In the current work, an aqueous SnO2 nanoparticulate precursor sol, which is free of organic contaminants and sorbed ions and is fully stable over time, was prepared in a highly reproducible manner from an alkoxide Sn(OR)4 just by mixing it with a large excess of pure neutral water. The precursor is formed as a separate liquid phase. The structure and purity of the precursor is revealed using XRD, SAXS, EXAFS, HRTEM imaging, FTIR, and XRF analysis. An unconventional approach for the estimation of the particle size based on the quantification of the Sn-Sn contacts in the structure was developed using EXAFS spectroscopy and verified using HRTEM. To construct sensors with a hierarchical 3D structure, we employed an unusual emulsification technique not involving any additives or surfactants, using simply the extraction of the liquid phase, water, with the help of dry butanol under ambient conditions. The originally generated crystalline but yet highly reactive nanoparticles form relatively uniform spheres through self-assembly and solidify instantly. The spheres floating in butanol were left to deposit on the surface of quartz plates bearing sputtered gold electrodes, producing ready-for-use gas sensors in the form of ca. 50 μm thick sphere-based-films. The films were dried for 24 h and calcined at 300 °C in air before use. The gas sensitivity of the structures was tested in the temperature range of 150-400 °C. The materials showed a very quickly emerging and reversible (20-30 times) increase in electrical conductivity as a response to exposure to air containing 100 ppm of H2 or CO and short (10 s) recovery times when the gas flow was stopped. PMID:26960813

  17. Synthesis Strategies to Design Structures for Catalytic Applications%硅基催化结构合成的策略

    Institute of Scientific and Technical Information of China (English)

    Harold H. KUNG; Mayfair C. KUNG

    2008-01-01

    Two approaches to synthesize silicon-based catalytic structures that aim at capturing the properties and functionalities of natural enzymes are described in this brief review: unit-by-unit synthesis of macromolecular units and templating/imprinting synthesis of nanocages. The unit-by-unit approach mimics the peptide synthesis method, offers atomic control of the structure, but is inefficient in synthesizing large structures such as nanocages. The templating/imprinting method is more suitable for nanocages at the sacrifice of atomic control, and the nanocages obtained are shown to possess properties exhibited by enzyme cavities.

  18. Synthesis and structure of mercury (II) chloride complex with 4-methyl-1,2,4-triazole thione

    International Nuclear Information System (INIS)

    Present article is devoted to synthesis and structure of mercury (II) chloride complex with 4-methyl-1,2,4-triazole thione. Thus the optimal conditions for synthesis of mercury complex with 4-methyl-1,2,4-triazole thione were defined. The parameters of unit cell were found. The intermolecular connections were defined as well.

  19. Computer-aided methods for analysis and synthesis of supersonic cruise aircraft structures

    Science.gov (United States)

    Giles, G. L.

    1976-01-01

    Computer-aided methods are reviewed which are being developed by Langley Research Center in-house work and by related grants and contracts. Synthesis methods to size structural members to meet strength and stiffness (flutter) requirements are emphasized and described. Because of the strong interaction among the aerodynamic loads, structural stiffness, and member sizes of supersonic cruise aircraft structures, these methods are combined into systems of computer programs to perform design studies. The approaches used in organizing these systems to provide efficiency, flexibility of use in an iterative process, and ease of system modification are discussed.

  20. Electrochemical Synthesis of Lead Alkoxide Complexes%铅醇盐配合物的电化学合成

    Institute of Scientific and Technical Information of China (English)

    朱传高; 王凤武; 朱琼霞

    2006-01-01

    在无隔膜电解槽中,电化学溶解铅金属制备铅醇盐配合物Pb(OEt)4、Pb(OBu)4、Pb(OCH2CH2-OCH3)4、Pb(OEt)2(acac)2、Pb(OBu)2(acac)2、Pb(OCH2CH2OCH3)2(acac)2[acac-为乙酰丙酮基]. 产物通过红外光谱(FT-IR)、拉曼光谱和核磁共振测试技术进行表征. 实验表明,采用有机胺溴化物为导电盐,可以防止阳极钝化,提高电合成效率;电解合成Pb(OCH2CH2OCH3)4、Pb(OEt)2(acac)2、Pb(OBu)2(acac)2、Pb(OCH2CH2OCH3)2(acac)2有较高的电流效率和产率.

  1. Total Synthesis, Structure Revision, and Absolute Configuration of (−)-Brevenal

    Science.gov (United States)

    Fuwa, Haruhiko; Ebine, Makoto; Bourdelais, Andrea J.; Baden, Daniel G.; Sasaki, Makoto

    2008-01-01

    Total synthesis of structure 1 originally proposed for brevenal, a nontoxic polycyclic ether natural product isolated from the Florida red tide dinoflagellate, Karenia brevis, was accomplished. The key features of the synthesis involved (i) convergent assembly of the pentacyclic polyether skeleton based on our developed Suzuki–Miyaura coupling chemistry and (ii) stereoselective construction of the multi-substituted (E,E)-dienal side chain by using copper(I) thiophen-2-carboxylate (CuTC)-promoted modified Stille coupling. The disparity of NMR spectra between the synthetic material and the natural product required a revision of the proposed structure. Detailed spectroscopic comparison of synthetic 1 with natural brevenal, coupled with the postulated biosynthetic pathway for marine polyether natural products, suggested that the natural product was most likely represented by 2, the C26 epimer of the proposed structure 1. The revised structure was finally validated by completing the first total synthesis of (−)-2, which also unambiguously established the absolute configuration of the natural product. PMID:17177450

  2. Synthesis and crystal structure of PdSnTe

    Energy Technology Data Exchange (ETDEWEB)

    Laufek, F. [Czech Geological Survey, Geologicka 6, 152 00 Praha 5 (Czech Republic)], E-mail: frantisek.laufek@geology.cz; Vymazalova, A. [Czech Geological Survey, Geologicka 6, 152 00 Praha 5 (Czech Republic); Navratil, J. [Joint Laboratory of Solid State Chemistry of IMC AS CR and University of Pardubice, Studentska 84, 532 10 Pardubice (Czech Republic); Drabek, M. [Czech Geological Survey, Geologicka 6, 152 00 Praha 5 (Czech Republic); Plasil, J. [Faculty of Science, Charles University, Albertov 6, 128 43 Praha 2 (Czech Republic); Plechacek, T. [Joint Laboratory of Solid State Chemistry of IMC AS CR and University of Pardubice, Studentska 84, 532 10 Pardubice (Czech Republic)

    2009-01-22

    The compound with composition PdSnTe was prepared by heating of stoichiometric amount of Pd, Sn and Te in silica glass tube at 400 deg. C. Its crystal structure was refined by Rietveld method using conventional X-ray powder diffraction data. PdSnTe shows orthorhombic symmetry, space group Pbca with unit cell parameters a = 6.5687(2), b = 6.6028(2), c = 12.8849(4) A, V = 558.8(1) A{sup 3} and Z = 8. The title compound can be viewed as a ternary-ordered variant of {alpha}-NiAs{sub 2}-type structure, it is isostructural with PtSiTe. Temperature dependence of electrical conductivity and Hall coefficient are presented, it suggests semimetallic or strongly degenerated semiconductor behaviour of the prepared compound.

  3. Electrochemical Synthesis and Structural Characterization of Titania Nanotubes

    OpenAIRE

    Nguyen, Que Anh

    2010-01-01

    Titania nanotubes have emerged as an exciting new material with a wide array of applications such as sensors, dye sensitized solar cells, and batteries due to their semi-conducting nature, high surface area, and distinct morphology. The nanotubes, synthesized electrochemically in a fluoride-containing electrolyte, are vertically aligned, close-packed, organized structures, with similar diameter and length. The formation mechanism responsible for the organized nanopore/nanotube arrays were exa...

  4. Synthesis and structural analysis of 13C-fatty acids

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The 13C-labeled fatty acids octanoic-1-13C acid and palmitic-l-13C acid were synthetically prepared from Ba 13CO3. The yield of the former was more than 90% and that of the latter was above 85%. MS, IR, 1H-NMR and 13NMR were performed to analyze the structures of the two 13C-fatty acids, compared with their unlabeled fatty acids.

  5. Synthesis and Structural Determination of Temocapril Sulfoxide Hydrochlorides

    Energy Technology Data Exchange (ETDEWEB)

    Seong, Seok Bong; Moon, Jong Taik; Kim, Jung Ahn; Choo, Dong Joon; Lee, Jae Yeol [Kyung Hee Univ., Seoul (Korea, Republic of)

    2012-10-15

    Impurity (or related substance) control in pharmaceutical products is a primary goal of drug development. Stringent international regulatory requirements have been in place for several years as outlined in the International Conference on Harmonization (ICH) Guidelines Q3A (R), Q3B (R) and Q3C. According to ICH guidelines, impurities associated with the manufacture of a drug substance, also known as an active pharmaceutical ingredient (API), are classified into the following categories: (1) organic impurities (process and drug-related); (2) inorganic impurities (3) residual solvents. Many potential impurities result from the API manufacturing process including starting materials, isomers, intermediates, reagents, solvents, catalysts and reaction by-products. These potential impurities should be investigated to determine process control mechanisms for their removal and the need for specification controls at appropriate points in the process. The suggested structures of the impurities can be synthesized and will provide the final evidence for their structures, previously determined by spectroscopic methods. Therefore it is essential to know the structure of these impurities in the bulk drug in order to alter the reaction condition and to reduce the quantity of impurity to an acceptable level. Isolation, identification and quantification of impurities help the pharmaceutical company to obtain a pure substance with less toxicity and safety in drug therapy.

  6. Synthesis and structure of linear hexanuclear manganese (Ⅱ) benzoate cluster

    Institute of Scientific and Technical Information of China (English)

    陈昌能; 陈久桐; 朱红平; 黄子祥; 刘秋田

    2001-01-01

    From a reaction system including benzoic acid and Mn(NO3)2 in alkali medium, two hexanuclear manganese benzoate cluster compounds have been synthesized. A compound [Et4N]2[Mn6(PhCOO)14] has been structurally characterized, which contains hexanuclear Mn11 moieties extending unlimitedly to form one-dimensional linear structure. Carboxyl oxygen atoms are bridged in variety of modes to the Mn atoms, forming an arrangement like a sinusoid for the Mn atoms. The structural parameters of these compounds were compared with the data obtained from EXAFS determination for the Mn cluster in the OEC of PS11, supporting that the coordination sphere of the Mn site in the OEC may contain carboxyl bridges. The possible combination modes between the carboxyl group and the Mn atoms have been suggested. The NMR signals exhibit widening and shift produced by the influence of the paramagnetic Mn" sites. The red-shift of the absorption in IR spectrum was observed to be attributed to the coordination of the carboxyl group to the Mn

  7. Synthesis, structure, and magnetic characterization of Cr4US8

    Science.gov (United States)

    Ward, Matthew D.; Chan, Ian Y.; Malliakas, Christos D.; Lee, Minseong; Choi, Eun Sang; Ibers, James A.

    2016-01-01

    The compound Cr4US8 has been synthesized at 1073 K and its crystal structure has been determined at 100 K. The structure is modulated with a two-fold commensurate supercell. The subcell may be indexed in an orthorhombic cell but weak supercell reflections lead to the monoclinic superspace group P21/c(α0γ)0s with two Cr sites, one U site, and four S sites. The structure comprises a three-dimensional framework of CrS6 octahedra with channels that are partially occupied by U atoms. Each U atom in these channels is coordinated by eight S atoms in a bicapped trigonal-prismatic arrangement. The magnetic behavior of Cr4US8 is complex. At temperatures above ~120 K at all measured fields, there is little difference between field-cooled and zero field-cooled data and χ(T) decreases monotonously with temperature, which is reminiscent of the Curie-Weiss law. At lower temperatures, the temperature dependence of χ(T) is complex and strongly dependent on the magnetic field strength.

  8. Synthesis and Crystal Structure of 3-(Trichloroacetyl) Indole

    Institute of Scientific and Technical Information of China (English)

    ZENG Xiang-Chao; XU Shi-Hai; LIU Po-Run; DENG Qin-Ying

    2005-01-01

    3-(Trichloroacetyl) indole has been synthesized by the reaction of indole with trichloroacetyl chloride in 73% yield, and its crystal structure was determined by X-ray diffraction method. The crystal is of orthorhombic, space group Pnma with a = 20.781(7), b = 6.857(2), c = 7.431(3) (A), V = 1058.8(6) (A)3, Z = 4, Mr = 262.51, Dc = 1.647 g/cm3, λ = 0.71073(A), μ(MoKα) = 0.833 mm(A) 1 and F(000) = 528. The structure was refined to R = 0.0286 and wR = 0.0749 for 1073 observed reflections with I > 2σ(I). It exhibits a characteristic plane structure consisting of all atoms except Cl(2) and Cl(2)A. Two kinds of intermolecular hydrogen bonds are formed: N(1)- H(8A)…O(1) and N(1)H(8A)…Cl(1). There also exist three kinds of π-π stacking in the crystal.

  9. Synthesis and Crystal Structure of Tetra(o-cyanobenzyl)tin

    Institute of Scientific and Technical Information of China (English)

    KUANG Dai-Zhi; JIANG Jiang-Ping; FENG Yong-Lan; ZHANG Fu-Xing; WANG Jian-Qiu; LUO Yi-Ming

    2008-01-01

    The tetra(o-eyanobenzyl)tin compound has been synthesized by the reaction of eyanobenzyl chloride with tin, and its molecular structure was characterized by elemental analysis,IR spectra, 1H NMR and X-ray diffraction. Crystal data for this compound: monoclinie, space group C2/c, M, = 583.24, a = 1.9629(2), b = 1.05967(13), c = 1.41249(18) nm, β = 118.180(2)°, V =2.5898(5) nm3, Z = 4, Dc =1.496 g/cm3, μ(MoKa) = 1.015 cm-1, F(000) = 1176, R = 0.0189, wR =0.0497 (observed reflections with Ⅰ 2σ(Ⅰ)) and R = 0.0218, wR = 0.0513 (all reflections).The molecular structure adopts a distorted tetrahedral geometry around the tin atom. The Sn…N weak interaction between the Sn and N atoms of cyano forms an intermolecular H-bonding, and the bond length is 0.3570 nm; the interaction between hydrogen of methylene and benzene ring of benzyl forms C-H…C with its bond length of 0.2817 nm; and the interaction among hydrogen of benzene ring and carbon of cyano forms Ph-H…C bond (0.2897 nm) of the σ…π interaction. A 3D chain structure is formed by the above weak intermolecular interactions.

  10. Uranium complexes with macrosyclic polyethers. Synthesis and structural chemical analysis

    International Nuclear Information System (INIS)

    This dissertation reports about studies on the chemical coordination behaviour of uranium of oxidation stages IV and VI with regard to twelve different macrocyclic ligands. For the preparation of the complexes, for every system a different method has been developed. The elementary analysis of the various complexes including the uranium had been done by X-ray fluorescence analysis, and the structural characterization proceeded via vibrational, uv-vis and emission spectroscopy as well as 1H-NMR and 13C-spin-lattice relaxation time studies. Conformational analysis of the polyethers used allowed the structural changes in the complexes to be observed. The structural analysis of the hydrous uranium VI crown ether complexes yielded information of characteristic features of these types of complexes. The first coordination sphere of the uranyl ion with covalently bonded anion remains unchanged. As to the water content, there is a certain range. Depending upon the solvent used, the complexes have two or four H2O molecules per formula unit. (orig./EF)

  11. The synthesis and structural characterization of novel transition metal fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Casteel, W.J. Jr.

    1992-09-01

    High purity KMF[sub 6] and K[sub 2]MF[sub 6] salts (M = Mo,Re, Ru, Os, Ir, Pt) are obtained from reduction hexafluorides. A rhombohedral unit cell is observed for KReF[sub 6]. Fluoride ion capture by Lewis acids from the hexafluorometallate (IV) salts affords high purity tetrafluorides for M = Mo, Re, Ru, Os, and Pd. The structure of RuF[sub 4] is determined from X-ray synchrotron and neutron powder data. Unit cells based on theorthorhombic PdF[sub 4] type cell are derived from X-ray powder data for ReF[sub 4] and OsF[sub 4]. Fluoride ion capture from KAgF[sub 4] provides the thermally unstable trifluoride as a bright, red, diamagnetic solid. The structure solution of AgF[sub 3] and redetermination of the AuF[sub 3] structure from X-ray synchrotron and neutron powder data demonstrate that the two are isostnictural. Thermal decomposition product of AgF[sub 3] is the mixed valence compound Ag[sup II]Ag[sub 2][sup III]F[sub 8]. Several new salts containing the (Ag - F)[sub n][sup n+] chain cation are prepared. The first linear (Ag - F)[sub n][sup n+] chain is observed in AgF[sup +]BF[sub 4 [sup [minus

  12. 8-(Dimethylamino)naphthylcopper(I), a novel stable organocopper compound with unusual structural features. A study concerning its synthesis, structure (X-ray) and reactivity. Its synthesis, crystal structure (X-ray) and reactivity

    NARCIS (Netherlands)

    Koten, G. van; Wehman, E.; Knotter, M.; Spelten, H.; Heijdenrijk, D.; Mak, A.N.S.; Stam, C.H.

    1987-01-01

    The synthesis and isolation of a hydrocarbon- and ether-insoluble organocopper compound containing the rigid 8-(dimethylamino)naphthyl group is described. An X-ray determination of its structure revealed a tetranuclear copper aggregate, in which the Cu atoms are arranged in a parallelogram (Cu...Cu

  13. Synthesis, Structure, Properties, and Bioimaging of a Fluorescent Nitrogen-Linked Bisbenzothiadiazole.

    Science.gov (United States)

    Mota, Alberto A R; Corrêa, José R; Carvalho, Pedro H P R; de Sousa, Núbia M P; de Oliveira, Heibbe C B; Gatto, Claudia C; da Silva Filho, Demétrio A; de Oliveira, Aline L; Neto, Brenno A D

    2016-04-01

    This paper describes the synthesis, structure, photophysical properties, and bioimaging application of a novel 2,1,3-benzothiadiazole (BTD)-based rationally designed fluorophore. The capability of undergoing efficient stabilizing processes from the excited state allowed the novel BTD derivative to be used as a stable probe for bioimaging applications. No notable photobleaching effect or degradation could be observed during the experimental time period. Before the synthesis, the molecular architecture of the novel BTD derivative was evaluated by means of DFT calculations to validate the chosen design. Single-crystal X-ray analysis revealed the nearly flat characteristics of the structure in a syn conformation. The fluorophore was successfully tested as a live-cell-imaging probe and efficiently stained MCF-7 breast cancer cell lineages. PMID:26930300

  14. Synthesis, Structural Characterization, and Bioactivity of the Stable Peptide RCB-1 from Ricinus communis.

    Science.gov (United States)

    Boldbaatar, Delgerbat; Gunasekera, Sunithi; El-Seedi, Hesham R; Göransson, Ulf

    2015-11-25

    The Ricinus communis biomarker peptides RCB-1 to -3 comprise homologous sequences of 19 (RCB-1) or 18 (RCB-2 and -3) amino acid residues. They all include four cysteine moieties, which form two disulfide bonds. However, neither the 3D structure nor the biological activity of any of these peptides is known. The synthesis of RCB-1, using microwave-assisted, Fmoc-based solid-phase peptide synthesis, and a method for its oxidative folding are reported. The tertiary structure of RCB-1, subsequently established using solution-state NMR, reveals a twisted loop fold with antiparallel β-sheets reinforced by the two disulfide bonds. Moreover, RCB-1 was tested for antibacterial, antifungal, and cytotoxic activity, as well as in a serum stability assay, in which it proved to be remarkably stable.

  15. Synthesis and Structure of a New Dinuclear Uranyl Complex

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    With a heptadentate compartmental Schiff-base ligand H3L (1, 3-di[o-(salicylimino) ph-enoxyl]-2-propanol), a new binuclear diuranyl complex [(UO2)2L(OH)]?3DMF, C38H45N5O13U2, was synthesized and the crystal structure was determined by X-ray diffraction techniques. The coordination geometry are two pentagonal bipyramids. In each pentagon four kinds of U-O (phenoxido, hydroxo, alkoxo and ether oxo) bonds are discussed.

  16. Synthesis and Structure of a Novel Disulfide-Containing Aniline

    Institute of Scientific and Technical Information of China (English)

    DENG,Shi-Ren; WU,Lei; WANG,Hao; ZHOU,Bin; LI,Zao-Ying

    2004-01-01

    @@ A novel disulfide-containing aniline, 8-dihydro-1H,4H-2,3,6,7-tetrathia-anthracen-9-ylamine (5) was synthesized.The single-crystal X-ray analysis of 4 indicates that the molecular has a non-planar structure, with its four sulfur atoms out of the plane of benzene ting. The designed molecular has the advantage of high theoretic specific capacity and reversibility,[1,2] when it is to be polymerized and used as the cathode material of the secondary lithium batteries.

  17. A uranium (VI) complex: Synthesis, structural and thermal kinetic analysis

    Science.gov (United States)

    Goel, Nidhi

    2016-08-01

    A new complex [UO2(2,6-DNP)2phen] (1) (2,6-DNP = 2,6-dinitrophenol, phen = 1,10-phenanthroline) was synthesized, and identified by elemental analysis, IR, Powder XRD and single crystal X-ray crystallography. Crystal structure provides the abundant information's about the bonding and geometry around the U(VI) metal center. The thermal decomposition was studied by TG-DSC, and the kinetics of thermolysis was investigated by applying model fitting as well as isoconversional methods. Explosion delay measurement (De) was also evaluated to determine the response of this complex under the condition of rapid heating.

  18. Preparation of titanium diboride powders from titanium alkoxide and boron carbide powder

    Indian Academy of Sciences (India)

    Hamed Sinaei Pour Fard; Hamidreza Baharvandi

    2011-07-01

    Titanium diboride powders were prepared through a sol–gel and boron carbide reduction route by using TTIP and B4C as titanium and boron sources. The influence of TTIP concentration, reaction temperature and molar ratio of precursors on the synthesis of titanium diboride was investigated. Three different concentrations of TTIP solution, 0.033/0.05/0.1, were prepared and the molar ratio of B4C to TTIP varied from 1.3 to 2.5. The results indicated that as the TTIP concentration had an important role in gel formation, the reaction temperature and B4C to TTIP molar ratio showed obvious effects on the formation of TiB2. Pure TiB2 was prepared using molar composition of Ti : B4C = 1 : 2.3 and the optimum synthesis temperature was 1200°C.

  19. Functionalized 4-Hydroxy Coumarins: Novel Synthesis, Crystal Structure and DFT Calculations

    Directory of Open Access Journals (Sweden)

    Olga Igglessi-Markopoulou

    2011-01-01

    Full Text Available A novel short-step methodology for the synthesis in good yields of functionalized coumarins has been developed starting from an activated precursor, the N-hydroxysuccinimide ester of O-acetylsalicylic acid. The procedure is based on a tandem C-acylation-cyclization process under mild reaction conditions. The structure of 3-methoxycarbonyl-4-hydroxy coumarin has been established by X-ray diffraction analysis and its geometry was compared with optimized parameters by means of DFT calculations.

  20. 9-Aryl Substituted Hydroxylated Xanthen-3-ones: Synthesis, Structure and Antioxidant Potency Evaluation

    OpenAIRE

    Veljović, Elma; Špirtović-Halilović, Selma; Muratović, Samija; Valek Žulj, Lidija; Roca, Sunčica; Trifunović, Snežana; Osmanović, Amar; Završnik, Davorka

    2015-01-01

    Oxidative stress is directly related to several diseases and symptoms, where antioxidant compounds, such as xanthenes, may become important in prevention and/or treatmant. Ten biologically active 9-aryl substituted 2,6,7-trihydroxyxanthen-3-one derivatives were synthesized using reliable one-pot synthesis and their structures were confirmed by IR, 1H and 13C NMR spectroscopy and mass spectrometry. Some of the synthesized compounds were scanned for their antioxidant potency using electrochemic...

  1. A novel series of thiosemicarbazone drugs: From synthesis to structure

    Science.gov (United States)

    Ebrahimi, Hossein Pasha; Hadi, Jabbar S.; Alsalim, Tahseen A.; Ghali, Thaer S.; Bolandnazar, Zeinab

    2015-02-01

    A new series of thiosemicarbazones (TSCs) and their 1,3,4-thiadiazolines (TDZs) containing acetamide group have been synthesized from thiosemicarbazide compounds by the reaction of TSCs with cyclic ketones as well as aromatic aldehydes. The structures of newly synthesized 1,3,4-thiadiazole derivatives obtained by heterocyclization of the TSCs with acetic anhydride were experimentally characterized by spectral methods using IR, 1H NMR, 13C NMR and mass spectroscopic methods. Furthermore, the structural, thermodynamic, and electronic properties of the studied compounds were also studied theoretically by performing Density Functional Theory (DFT) to access reliable results to the experimental values. The molecular geometry, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) and Mulliken atomic charges of the studied compounds have been calculated at the B3LYP method and standard 6-31+G(d,p) basis set starting from optimized geometry. The theoretical 13C chemical shift results were also calculated using the gauge independent atomic orbital (GIAO) approach and their respective linear correlations were obtained.

  2. One dimensional coordination polymers: Synthesis, crystal structures and spectroscopic properties

    Science.gov (United States)

    Karaağaç, Dursun; Kürkçüoğlu, Güneş Süheyla; Şenyel, Mustafa; Şahin, Onur

    2016-11-01

    Two new one dimensional (1D) cyanide complexes, namely [M(4-aepy)2(H2O)2][Pt(CN)4], (4-aepy = 4-(2-aminoethyl)pyridine M = Cu(II) (1) or Zn(II) (2)), have been synthesized and characterized by vibrational (FT-IR and Raman) spectroscopy, single crystal X-ray diffraction, thermal and elemental analyses techniques. The crystallographic analyses reveal that 1 and 2 are isomorphous and isostructural, and crystallize in the monoclinic system and C2 space group. The Pt(II) ions are coordinated by four cyanide-carbon atoms in the square-planar geometry and the [Pt(CN)4]2- ions act as a counter ion. The M(II) ions display an N4O2 coordination sphere with a distorted octahedral geometry, the nitrogen donors belonging to four molecules of the organic 4-aepy that act as unidentate ligands and two oxygen atoms from aqua ligands. The crystal structures of 1 and 2 are similar each other and linked via intermolecular hydrogen bonding, Pt⋯π interactions to form 3D supramolecular network. Vibration assignments of all the observed bands are given and the spectral features also supported to the crystal structures of the complexes.

  3. Synthesis and structural characterization of actinide oxalate compounds

    International Nuclear Information System (INIS)

    Oxalic acid is a well-known reagent to recover actinides thanks to the very low solubility of An(IV) and An(III) oxalate compounds in acidic solution. Therefore, considering mixed-oxide fuel or considering minor actinides incorporation in ceramic fuel materials for transmutation, oxalic co-conversion is convenient to synthesize mixed oxalate compounds, precursors of oxide solid solutions. As the existing oxalate single crystal syntheses are not adaptable to the actinide-oxalate chemistry or to their manipulation constrains in gloves box, several original crystal growth methods were developed. They were first validate and optimized on lanthanides and uranium before the application to transuranium elements. The advanced investigations allow to better understand the syntheses and to define optimized chemical conditions to promote crystal growth. These new crystal growth methods were then applied to a large number of mixed An1(IV)-An2(III) or An1(IV)-An2(IV) systems and lead to the formation of the first original mixed An1(IV)-An2(III) and An1(IV)-An2(IV) oxalate single crystals. Finally thanks to the first thorough structural characterizations of these compounds, single crystal X-ray diffraction, EXAFS or micro-RAMAN, the particularly weak oxalate-actinide compounds structural database is enriched, which is essential for future studied nuclear fuel cycles. (author)

  4. Synthesis and Crystal Structure of a Degraded Dehydroabietylamine Thiophene Imine

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A degraded dehydroabietylamine thiophene imine (C24H30NS, Mr-364.55)has been synthesized from dehydroabietic acid, and its structure was characterized by IR, 1HNMR spectroscopy and single-crystal X-ray diffraction.White crystals of the title compound crystallize in the monoclinic system, space group P21 with a = 5.9490(12), b = 16.337(3), c = 10.780(2)(A), β= 92.21(3)°, V = 1046.9(3)(A)3, Z = 2, Dc = 1.156g/cm3, λ= 0.71073(A),μ= 0.162 mm-1, F(000) = 394, the final R = 0.0443 and wR = 0.0805 for 1325 observed reflections with(I>2σ(I).The imine group was directly attached to the chiral carbon atom of tricyclo hydrophenthenrane structure with a trans configuration.The dihedral angle between two aromatic rings is 88.3°.

  5. Topology Synthesis of Structures Using Parameter Relaxation and Geometric Refinement

    Science.gov (United States)

    Hull, P. V.; Tinker, M. L.

    2007-01-01

    Typically, structural topology optimization problems undergo relaxation of certain design parameters to allow the existence of intermediate variable optimum topologies. Relaxation permits the use of a variety of gradient-based search techniques and has been shown to guarantee the existence of optimal solutions and eliminate mesh dependencies. This Technical Publication (TP) will demonstrate the application of relaxation to a control point discretization of the design workspace for the structural topology optimization process. The control point parameterization with subdivision has been offered as an alternative to the traditional method of discretized finite element design domain. The principle of relaxation demonstrates the increased utility of the control point parameterization. One of the significant results of the relaxation process offered in this TP is that direct manufacturability of the optimized design will be maintained without the need for designer intervention or translation. In addition, it will be shown that relaxation of certain parameters may extend the range of problems that can be addressed; e.g., in permitting limited out-of-plane motion to be included in a path generation problem.

  6. Bridged bis-BODIPYs: their synthesis, structures and properties.

    Science.gov (United States)

    Kesavan, Praseetha E; Das, Sudipta; Lone, Mohsin Y; Jha, Prakash C; Mori, Shigeki; Gupta, Iti

    2015-10-21

    A series of bis-BODIPYs 1-6 bridged via thiophene, furan, N-alkylcarbazole, triphenyl-amine, para- and meta-phenylene groups have been synthesized and characterized by various spectroscopic techniques. The change in the spectroscopic properties of bis-BODIPYs upon varying the size of spacers was studied. X-ray crystal structures of three bis-BODIPYs containing triphenylamine, para- and meta-phenylene bridges were solved. Intermolecular C(H)π and ππ stacking interactions were observed in solid state structures of three bis-BODIPYs. The dihedral angles between the spacer unit and two boron-dipyrrin units were lower in all three compounds as compared to their corresponding monomers. This suggests increased interactions between the two boron-dipyrrin units in molecules which are in turn reflected in the anodic shifts in their reduction potentials. DFT studies indicated effective electronic interactions between spacers and two boron dipyrrin units in all the bis-BODIPYs. The calculated HOMO-LUMO gap was found to be lower for bis-BODIPY having bulky carbazole spacers and higher for bis-BODIPY having smaller furan spacers. Changing the spacer size clearly affected the spectroscopic properties of the bis-BODIPYs and red shifted absorption and emission maxima were observed for bis-BODIPYs with furan and thiophene spacers as compared to bis-BODIPYs with phenylene or bulky aromatic spacers. PMID:26373792

  7. Synthesis, properties and supramolecular structure of piperazinediium thiosulfate monohydrate

    Indian Academy of Sciences (India)

    Bikshandarkoil R Srinivasan; Ashish R Naik; Sunder N Dhuri; Christian Näther; Wolfgang Bensch

    2011-01-01

    Aqueous reaction of ammonium thiosulfate with piperazine (pip) results in the formation of the title compound (pipH2)[S2O3]$\\cdot$H2O 1 (pipH2 = piperazinediium) in good yield. 1 was characterized by elemental analysis, IR, Raman andNMRspectra, X-ray powder pattern and its structure was determined. On heating at 100°C, 1 transforms to anhydrous piperazinediium thiosulfate 2, which can be rehydrated to the monohydrate on exposure tomoisture. The structure of 1 consists of two crystallographically independent piperazinediium (pipH2)2+ cations located on inversion centers, a thiosulfate anion and a lattice water. The organic cations, thiosulfate anion and lattice water are linked by six varieties of hydrogen bond namely O-H$\\cdots$O, O-H$\\cdots$S, N-H$\\cdots$O, N-H$\\cdots$S, C-H$\\cdots$O and C-H$\\cdots$S, leading to the formation of alternating layers of (pipH2)2+ cations and water linked thiosulfate chains. A comparative study of several compounds charge balanced by the piperazinediium cation is described.

  8. Synthesis, structure, and mechanical properties of silica nanocomposite polyrotaxane gels

    Science.gov (United States)

    Matsui, Daisuke; Mayumi, Koichi

    2015-01-01

    Summary A significantly soft and tough nanocomposite gel was realized by a novel network formed using cyclodextrin-based polyrotaxanes. Covalent bond formation between the cyclic components of polyrotaxanes and the surface of silica nanoparticles (15 nm diameter) resulted in an infinite network structure without direct bonds between the main chain polymer and the silica. Small-angle X-ray scattering revealed that the homogeneous distribution of silica nanoparticles in solution was maintained in the gel state. Such homogeneous nanocomposite gels were obtained with at least 30 wt % silica content, and the Young’s modulus increased with silica content. Gelation did not occur without silica. This suggests that the silica nanoparticles behave as cross-linkers. Viscoelastic measurements of the nanocomposite gels showed no stress relaxation regardless of the silica content for rubber theory. In addition, the composite gels were tough enough to completely maintain the network structure under 80% compression strain. These toughness and softness properties are attributable to both the characteristic sliding of polymer chains through the immobilized cyclodextrins on the silica nanoparticle and the entropic contribution of the cyclic components to the elasticity of the gels. PMID:26664642

  9. Hydrotherrnal synthesis, structure and property of nano-BaTiO3-based dielectric materials

    Institute of Scientific and Technical Information of China (English)

    DING; ShiIiang

    2001-01-01

    [1]Su, W., The proposition of technical progress and development for barium solts, Inorganic Salt Industry (in Chinese), 1992,3: 5.[2]West, A. R., Solid State Chemistry and Its Applications, New Delhi: John Wiley, 1984, 367,534-548.[3]Heistand, R. H., Duquette, L. G., Skeele, E P. et al., Coprecipitated barium titanate(BaTiO3)-based powder formulated from catechol coordination compounds, Ceram. Trans., 1988, 2: 94.[4]Ding, S. W., Ma, G. C., Wang, Z. Q. et al., Synthesis, structure and properties of BaZrxTi1-xO3 · yLa203 solid solutions, Chemical Journal of Chinese Universities (in Chinese), 1998, 19: 1542.[5]Ding, S. W., Zhai, Y. Q., Li, X. M. et al., Synthesis, structure and properties of Ba1-xCaxSnyTi1-y03 solid solutions, Acta Chim. Sinica (in Chinese), 2000, 58:1139.[6]Ding, S. W., Zhal, Y. Q., Li, Y. et al., Synthesis, structure and properties of Bal-xSrxMyTil-yO3 nano-materials, Science in China, Ser. B, 2000, 43(3): 283.[7]

  10. Frequency Domain Structural Synthesis Applied to Quasi-Static Crack Growth Modeling

    Directory of Open Access Journals (Sweden)

    Young W. Kwon

    2009-01-01

    Full Text Available Quasi-static crack growth in a composite beam was modeled using the structural synthesis technique along with a finite element model. The considered crack was an interface crack in the shear mode (i.e. mode II, which occurs frequently in the scarf joint of composite structures. The analysis model was a composite beam with an edge crack at the midplane of the beam subjected to a three-point bending load. In the finite element model, beam finite elements with translational degrees of freedom only were used to model the crack conveniently. Then, frequency domain structural synthesis (substructure coupling was applied to reduce the computational time associated with a repeated finite element calculation with crack growth. The quasi-static interface crack growth in a composite beam was predicted using the developed computational technique, and its result was compared to experimental data. The computational and experimental results agree well. In addition, the substructure-based synthesis technique showed the significantly improved computational efficiency when compared to the conventional full analysis.

  11. Synthesis and applications of novel silver nanoparticle structures

    Science.gov (United States)

    Dukes, Kyle

    The field of nanotechnology is rapidly expanding across disciplines as each new development is realized. New exciting technologies are being driven by advances in the application of nanotechnology; including biochemical, optical, and semiconductors research. This thesis will focus on the use of silver nanoparticles as optical labels on cells, methods of forming different small structures of silver nanoparticles, as well as the use of silver nanoparticles in the development of a photovoltaic cell. Silver nanoparticles have been modified with self-assembled monolayers of hydroxyl-terminated long chain thiols and encapsulated with a silica shell. The resulting core-shell nanoparticles were used as optical labels for cell analysis using flow cytometry and microscopy. The excitation of plasmon resonances in nanoparticles results in strong depolarized scattering of visible light permitting detection at the single nanoparticle level. The nanoparticles were modified with neutravidin via epoxide-azide coupling chemistry and biotinylated antibodies targeting cell surface receptors were bound to the nanoparticle surface. The nanoparticle labels exhibited long-term stability under physiological conditions without aggregation or silver ion leaching. Labeled cells exhibited two orders of magnitude enhancement of the scattering intensity compared to unlabeled cells. Dimers of silver nanoparticles have been fabricated by first immobilizing a monolayer of single silver nanoparticles onto poly(4-vinylpyridine) covered glass slides. The monolayer was then exposed to adenine, which has two amines which will bind to silver. The nanoparticle monolayer, now modified with adenine, is exposed to a second suspension of nanoparticles which will bind with the amine modified monolayer. Finally, a thin silica shell is formed about the structure via solgel chemistry to prevent dissolution or aggregation upon sonication/striping. Circular arrays of silver nanoparticels are developed using a

  12. The synthesis and structural characterization of novel transition metal fluorides

    Energy Technology Data Exchange (ETDEWEB)

    Casteel, W.J. Jr.

    1992-09-01

    High purity KMF{sub 6} and K{sub 2}MF{sub 6} salts (M = Mo,Re, Ru, Os, Ir, Pt) are obtained from reduction hexafluorides. A rhombohedral unit cell is observed for KReF{sub 6}. Fluoride ion capture by Lewis acids from the hexafluorometallate (IV) salts affords high purity tetrafluorides for M = Mo, Re, Ru, Os, and Pd. The structure of RuF{sub 4} is determined from X-ray synchrotron and neutron powder data. Unit cells based on theorthorhombic PdF{sub 4} type cell are derived from X-ray powder data for ReF{sub 4} and OsF{sub 4}. Fluoride ion capture from KAgF{sub 4} provides the thermally unstable trifluoride as a bright, red, diamagnetic solid. The structure solution of AgF{sub 3} and redetermination of the AuF{sub 3} structure from X-ray synchrotron and neutron powder data demonstrate that the two are isostnictural. Thermal decomposition product of AgF{sub 3} is the mixed valence compound Ag{sup II}Ag{sub 2}{sup III}F{sub 8}. Several new salts containing the (Ag - F){sub n}{sup n+} chain cation are prepared. The first linear (Ag - F){sub n}{sup n+} chain is observed in AgF{sup +}BF{sub 4 {sup {minus}}} which crystallizes in a tetragonal unit. AgFAuF{sub 4} has a triclinic unit cell and is isostructural with CuFAuF{sub 4}. AgFAuF{sub 6} has an orthorhombic unit cell and appears to be isostructural with AgFAsF{sub 6}. A second mixed valence silver fluoride, Ag{sup II}Ag{sup III}F{sub 5}, is prepared, which magnetic measurements indicate is probably an AgF{sup +} salt. Magnetic data for all of the AgF{sup +} salts exhibit low magnitude, temperature independent paramagnetism characteristic of metallic systems. Cationic AG(II) in acidic AHF solutions is a powerful oxidizer, capable of oxidizing Xe to Xe(II) and O{sub 2} to O{sub 2}{sup +}. Reactions with C{sub 6}F{sub 6} and C{sub 3}F{sub 6} suggest an electron capture mechanism for cationic AG(II) oxidations.

  13. Synthesis and Characterization of Titanosilicate with the Structure of Umbite

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A zeolitic titanosilicate with the composition of K2TiSi3O9*H2O, a structural analogue of natural mineral umbite K2ZrSi3O9*H2O, was hydrothermally synthesized in the SiO2-TiO2-K2O-H2O system and characterized by means of powder X-ray diffraction, SEM, IR and thermal analysis. The effects of TiO2/SiO2 and OH-/SiO2 ratios on the crystallization of the umbite were discussed. The influence of the organic additives on the morphology of the crystal was also investigated and the crystals with different shapes were obtained.

  14. Synthesis and Structure of Bis(4-nitrobenzaldehyde thiosemicarbazone) Cadmium Iodide

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The title complex, bis(4-nitrobenzaldehyde thiosemicarbazone) cadmium iodide (C16H16CdI2N8O4S2) crystallizes in the triclinic system, space group P1 with a=9.632(2), b=11.227(2), c=14.031(3), α= 67.50(3), β= 86.99(3), γ= 66.64(3)°, V=1278.13, Z = 2, Dc = 2.117gcm-3, F(000) = 772, μ =3.472mm-1 MoKα radiation (λ=0.71073), R = 0.0443, wR= 0.1425 for 4529 observed reflections [I>2σ(I)] of 4731 independent reflections. The result shows that the structure contains CdL2I2 (where L = 4-nitrobenzaldehyde thiosemicarbazone) distorted tetrahedral units in which the two ligands are S-bonded as monodentate to cadmium ion; the two iodide ions are also coordinated to Cd(II).

  15. Synthesis and Crystal Structure of Tetranuclear Zinc Benzoate

    Institute of Scientific and Technical Information of China (English)

    YIN Ming-cai; WANG Chi-wei; AI Chang-chun; YUAN Liang-jie; SUN Ju-tang

    2004-01-01

    A tetranuclear zinc benzoate Zn4O(C6H5CO2)6 was synthesized and characterized by X-ray single crystal determination. It crystallizes in cubic, space group Ia-3d. Its crystal cell is very large, a=4.100 63(18) nm, V=68.953(5) nm3 and Z = 48. The structure is composed of discrete Zn4O(C6H5CO2)6 molecules. In each molecule, four zinc atoms are held together by a central oxygen atom, which results in the formation of a regular tetrahedron. All benzoate ligands coordinate to zinc atoms in a bidentate bridging mode. Each zinc atom is in a slightly distorted tetrahedral geometry, coordinated by three benzoate oxygen atoms and the central oxygen atom. The intermolecular interactions result in the formation of a three-dimensional supramolecular framework, with non-intersecting parallel channels.

  16. Amidinate Ligands in Zinc coordination sphere: Synthesis and structural diversity

    Indian Academy of Sciences (India)

    SRINIVAS ANGA; INDRANI BANERJEE; TARUN K PANDA

    2016-06-01

    A one-pot reaction involving neosilyllithium and three different carbodiimides (RN=C=NR, R =cyclohexyl, isopropyl and tert-butyl) in diethyl ether, followed by the addition of anhydrous $ZnCl_{2}$, afforded,in high yield, corresponding homoleptic zinc amidinate complexes having the molecular formulae$[Zn{CyN=C(CH_{2}SiMe_{3})NCy}_{2}]$ (1),$[Zn^{{i}PrN=C(CH_{2}SiMe_{3})N^{i}Pr}_{2}]$ (2) and [Zn$^{{t}BuN=C(CH_{2}SiMe_{3})N^{t}Bu}_{2}]$ (3), respectively, and amidinato moieties in the zinc coordination sphere. Solid state structures of complexes1-3 are reported thereafter - all the three complexes are isostructural, and each of them consists of twofour-membered metallacycles.

  17. SYNTHESIS, CHARACTERIZATION AND CRYSTAL STRUCTURE OF BIS-(2-HYDROXYBENZALDEHYDEDIAMINOGUANIZONE

    Directory of Open Access Journals (Sweden)

    Diana Dragancea, Vladimir B. Arion, Sergiu Shova

    2008-12-01

    Full Text Available The new ligand, bis(2-hydroxybenzaldehydediaminoguanizone (1 has been synthesized and characterized by elemental analysis, IR and 1H NMR spectroscopies. The crystal structure of the compound was determined by X-ray diffraction. The ligand C15H15N5O2·C2H5OH crystallizes in the monoclinic space group P21/c with unit cell parameters a = 8.9102(3, b = 10.0357(3, c = 19.7618(6 Å, β = 98.385(2°, Z = 4, V = 1748.21(9 Å3, R1 = 0.040. The amino form of the ligand adopts a planar conformation stabilized by two intramolecular hydrogen bonds of the type O–H···N, in which the H atoms of the central amino group are directed to the lone-pair regions of the azomethine nitrogen atoms.

  18. Synthesis and crystal structure of ethyl benzimidazole-2-yl phosphonate

    Institute of Scientific and Technical Information of China (English)

    HU, Fang-Zhong; WENG, Lin-Hong; YANG, Hua-Zheng; ZOU, Xiao-Mao

    2000-01-01

    When N-cyanoimido- ( O, O-diethyl ) phosphonyl/ S-methyl thiocarbonate (1) was treated with o-phenylenediamine in the presence of Et3N in ethanol, diethyl benzimidazole-2-yl recrys phonate(2) was obtained and hydrolyzed during the recrys tallization in MeOH/H2O, generating ethyl benzimidazole-2-yl phosphonate(3). The crystal structure of compound 3 was determined by X-ray diffraction method. The crystals belong to monoclinic, space rgoup C2/c, a=1.78408(18), b=O. 83725(9), c=1.67401(18) nm, β= 118.997(2)°, v=2. 1870(4) nm3, z=8, Dc=1.374g/cm3, F(000)=944.The final R and wR are 0.0499 and 0.1436, respectively. The mechanism of the above reaction is also discussed.

  19. Peloruside B, a Potent Antitumor Macrolide from the New Zealand Marine Sponge Mycale hentscheli: Isolation, Structure, Total Synthesis and Bioactivity

    OpenAIRE

    Singh, A. Jonathan; Xu, Chun-Xiao; Xu, Xiaoming; West, Lyndon M.; Wilmes, Anja; Chan, Ariane; Hamel, Ernest; John H Miller; Peter T. Northcote; Ghosh, Arun K.

    2010-01-01

    Peloruside B (2), a natural congener of peloruside A (1), was isolated in sub-milligram quantities from the New Zealand marine sponge Mycale hentscheli. Peloruside B promotes microtubule polymerization and arrests cells in the G2M phase of mitosis similar to paclitaxel, and its bioactivity was comparable to that of peloruside A. NMR-directed isolation, structure elucidation, structure confirmation by total synthesis and bioactivity of peloruside B are described in this article. The synthesis ...

  20. Uranium hetero-bimetallic complexes: synthesis, structure and magnetic properties

    International Nuclear Information System (INIS)

    The aim of this thesis is to synthesize molecular complexes with uranium and transition metal ions in close proximity, to determine the nature of the magnetic interaction between them. We decided to use Schiff bases as assembling ligands, which are unusual for uranium (IV). Although the simplest Schiff bases, such as H2Salen, lead to ligand exchange reactions, the bi-compartmental Schiff base H4L6 (bis(3-hydroxy-salicylidene) - 2,2-dimethyl-propylene) allows the crystal structure determination of the complex [L6Cu(pyr)]U[L6Cu].2pyr, obtained by reaction of the metallo-ligand H2L6Cu with U(acac)4. In this manner, the complexes [L6Co(pyr)]2U and [L6Ni(pyr)]2U.pyr were also isolated, as well as the compounds in which the paramagnetic ions have been exchanged by the diamagnetic ions ZnII, ZrIV and ThIV': [L6Zn(pyr)]2U, [L6Cu]2Zr and [L6Cu(pyr)]Th[L6Cu].2pyr. These complexes are the first which involve three metallic centres assembling by the means of a hexa-dentate Schiff base. The crystalline structures show, for all these complexes, the outstanding orthogonal arrangement of the two fragments L6M around the central atom which is in a dodecahedral environment of eight oxygen atoms of two Schiff bases. The syntheses of the isostructural complexes Cu2II and Zn2U in which the uranium (IV) ion is close, in the first one, to the paramagnetic ion CuII and, in the second one, to the diamagnetic ion ZnII, has allowed the use of the empiric method to determine the nature of the magnetic interaction between an f element and a transition metal. The comparison of the magnetic behaviour of two complexes Cu2U and Zn2U, expressed by the variation of χT vs T, reveals the ferromagnetic interaction in the heart of the triad Cu-U-Cu. The magnetic behaviour of the complexes Cu2Th et Cu2Zr which does not show any coupling between the two copper (II) ions and the weak antiferromagnetic interaction in the Ni2U compound, favour the hypothesis of ferromagnetic coupling between UIV and Cu

  1. Organometallic chemistry of chiral diphosphazane ligands: Synthesis and structural characterisation

    Indian Academy of Sciences (India)

    Kannan Raghuraman; Swadhin K Mandal; T S Venkatakrishnan; Setharampattu S Krishnamurthy; Munirathinam Nethaji

    2002-08-01

    The diphosphazane ligands of the type, (C20H12O2)PN(R)P(E)Y2 (R = CHMe2 or ()-∗CHMePh; E = lone pair or S; Y2 = O2C20H12 or Y = OC6H5 or OC6H4Me-4 or OC6H4OMe-4 or OC6H4Bu-4 or C6H5) bearing axially chiral 1,1'-binaphthyl-2,2'-dioxy moiety have been synthesised. The structure and absolute configuration of a diastereomeric palladium complex, [PdCl2{2-((O2C20H12)PN(()-∗CHMePh)PPh2}] has been determined by X-ray crystallography. The reactions of [CpRu(PPh3)2Cl] with various symmetrical and unsymmetrical diphosphazanes of the type, X2PN(R)PYY' (R = CHMe2 or ()-∗CHMePh; X = C6H5 or X2 = O2C20H12; Y = Y' = C6H5 or Y = C6H5, Y' = OC6H4Me-4 or OC6H3Me2-3,5 or N2C3HMe2-3,5) yield several diastereomeric neutral or cationic half-sandwich ruthenium complexes which contain a stereogenic metal center. In one case, the absolute configuration of a trichiral ruthenium complex, viz. [Cp∗Ru{2-Ph2PN(()-∗CHMePh)∗PPh (N2C3HMe2-3,5)}Cl] is established by X-ray diffraction. The reactions of Ru3(CO)12 with the diphosphazanes (C20H12O2)PN(R)PY2 (R = CHMe2 or Me; Y2=O2C20H12 or Y = OC6H5 or OC6H4Me-4 or OC6H4OMe-4 or OC6H4Bu-4 or C6H5) yield the triruthenium clusters [Ru3(CO)10{-(O2C20H12)PN(R)PY2}], in which the diphosphazane ligand bridges two metal centres. Palladium allyl chemistry of some of these chiral ligands has been investigated. The structures of isomeric 3-allyl palladium complexes, [Pd(3-1,3-R'2-C3H3){2-(rac)-(O2C20H12)PN(CHMe2)PY2}](PF6) (R' = Me or Ph; Y = C6H5 or OC6H5) have been elucidated by high field twodimensional NMR spectroscopic and X-ray crystallographic studies.

  2. Synthesis and study of nano-structured cellulose acetate based materials for energy applications

    International Nuclear Information System (INIS)

    Nano-structured materials have unique properties (high exchange areas, containment effect) because of their very low characteristic dimensions. The elaboration way set up in this PhD work consists in applying the classical processes for the preparation of aerogel-like materials (combining sol-gel synthesis and CO2 supercritical extraction) to cellulosic polymers. This work is divided in four parts: a literature review, the presentation and the study of the chemical synthesis that leads to cellulose acetate-based aerogel, the characterizations (chemical, structural and thermal) of the elaborated nano-materials, and finally the study of the first carbons that were obtained after pyrolysis of the organic matrix. The formulations and the sol-gel protocol lead to chemical gels by crosslinking cellulose acetate using a poly-functional iso-cyanate. The dry materials obtained after solvent extraction with supercritical CO2 are nano-structured and mainly meso-porous. Correlations between chemical synthesis parameters (reagent concentrations, crosslinking rate and degree of polymerisation) and porous properties (density, porosity, pore size distribution) were highlighted thanks to structural characterizations. An ultra-porous reference aerogel, with a density equals to 0,245 g.cm-3 together with a meso-porous volume of 3,40 cm3.g-1 was elaborated. Once in granular shape, this material has a thermal conductivity of 0,029 W.m-1.K-1. In addition, carbon materials produced after pyrolysis of the organic matrix and after grinding are nano-structured and nano-porous, even if important structural modifications have occurred during the carbonization process. The elaborated materials are evaluated for applications in relation with energy such as thermal insulation (organic aerogels) but also for energy conversion and storage through electrochemical way (carbon aerogels). (author)

  3. Synthesis and structure of iridium complex with thiocarbamide

    International Nuclear Information System (INIS)

    A single crystal of the [Ir(Thio)2Cl4][Ir(Thio)4Cl2] compound synthesized by the reaction of K3[IrCl6] with thiocarbamide (Thio, SC(NH2)2) in a microwave field is investigated using X-ray diffraction. The compound crystallizes in the monoclinic crystal system with space group Cc(Cs4). The unit cell parameters are as follows: a = 13.554(1) A, b = 8.251(1) A, c = 24.992(2) A, β = 92.58(1)o, V = 2791.87(10) A3, and Z = 4. The compound has an island structure with two crystallographically independent iridium atoms. Thiocarbamide is coordinated to the central atom through the sulfur atom. The coordination sphere of the Ir(1) atom involves two Cl atoms and four S atoms, whereas the coordination sphere of the Ir(2) atom consists of four Cl atoms and two S atoms. The assignment of the bands in the IR absorption spectrum of the synthesized compound is presented. The thermal behavior of the compound in air is investigated.

  4. Synthesis, structural and fungicidal studies of hydrazone based coordination compounds.

    Science.gov (United States)

    Sharma, Amit Kumar; Chandra, Sulekh

    2013-02-15

    The coordination compounds of the Co(II), Ni(II) and Cu(II) metal ions derived from imine based ligand, benzil bis(carbohydarzone) were structurally and pharmaceutically studied. The compounds have the general stoichiometry [M(L)]X(2) and [Co(L)X(2)], where M=Ni(II) and Cu(II), and X=NO(3)(-) and Cl(-) ions. The analytical techniques like elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, UV/Visible, NMR, ESI mass and EPR were used to study the compounds. The key IR bands, i.e., amide I, amide II and amide III stretching vibrations accounts for the tetradentate metal binding nature of the ligand. The electronic and EPR spectral results suggest the square planar Ni(II) and Cu(II) complexes (g(iso)=2.11-2.22) and tetragonal geometry Co(II) complexes (g(iso)=2.10-2.17). To explore the compounds in the biological field, they were examined against the opportunistic pathogens, i.e., Alternaria brassicae, Aspergillus niger and Fusarium oxysporum. The partial covalent character of metal-ligand bond is supported by the orbital reduction factor k (0.62-0.92) and nephalauxetic parameter β (0.55-0.57).

  5. Polymer supported nickel complex: Synthesis, structure and catalytic application

    Indian Academy of Sciences (India)

    Alekha Kumar Sutar; Tungabidya Maharana; Yasobanta Das; Prasanta Rath

    2014-11-01

    In the present investigation, a new synthetic route for a novel recyclable free [3-MOBdMBn-Ni] and polystyrene-anchored [P-3-MOBdMBn-Ni] nickel complexes is presented. The free and polymer-anchored metal complexes were synthesized by the reaction of nickel (II) with one molar equivalent of unsupported N N′-bis (2-Hydroxy-3-methoxybenzaldehyde) 4-Methylbenzene-1,2-diamine (3-MOBdMBn) or polymersupported (P-3-MOBdMBn) Schiff-base ligand in methanol under nitrogen atmosphere. The advantages of these polymer-supported catalysts are the low cost of catalyst and recyclability up to six times, due to easy availability of materials and simple synthetic route. The higher efficiency of complexation of nickel on the polymer-anchored 3-MOBdMBn Schiff base than the unsupported analogue is another advantage of this catalyst system. The structural study reveals that nickel(II) complex of 3-MOBdMBn is square planar in geometry. The catalytic activity of nickel complex towards the oxidation of phenol was investigated in the presence of hydrogen peroxide. Experimental results indicate that the reactivity of P-3-MOBdMBn-Ni was dramatically affected by the polymer support compared to free 3-MOBdMBn-Ni. The rates of oxidation (R) for unsupported and supported catalysts are 1.37 × 10-6 mole dm-3 s-1 and 2.33 × 10-6 mole dm-3 s-1 respectively.

  6. Phosphine derivatives of sparfloxacin - Synthesis, structures and in vitro activity

    Science.gov (United States)

    Komarnicka, Urszula K.; Starosta, Radosław; Guz-Regner, Katarzyna; Bugla-Płoskońska, Gabriela; Kyzioł, Agnieszka; Jeżowska-Bojczuk, Małgorzata

    2015-09-01

    We synthesized two derivatives of sparfloxacin (HSf): aminomethyl(diphenyl)phosphine (PSf) and its oxide (OPSf). The compounds were characterized by NMR spectroscopy, MS and elemental analysis. In addition, the molecular structures of the compounds were determined using DFT and X-ray (OPSf) analysis. The antibacterial activity of HSf and both derivatives was tested against four reference and fifteen clinical Gram-positive and Gram-negative strains of bacteria (sensitive or resistant to fluoroquinolones). The results showed that the activity of PSf was similar to or higher than the activity of HSf, while OPSf was found significantly less active. The compounds were also tested in vitro toward the following cancer cell lines: mouse colon carcinoma (CT26) and human lung adenocarcinoma (A549). Regardless of the cancer cell line, derivatization of HSf resulted in the gradual increase of cytotoxicity. OPSf exhibited the highest one (4 h - incubation time: IC50(CT26) = 51.0 ± 1.2; IC50(A549) = 74.9 ± 1.4 and 24 h: IC50(CT26) = 109.2 ± 8.8; IC50(A549) = 52.7 ± 9.2).

  7. Benzofuranyl Esters: Synthesis, Crystal Structure Determination, Antimicrobial and Antioxidant Activities

    Directory of Open Access Journals (Sweden)

    C. S. Chidan Kumar

    2015-09-01

    Full Text Available A series of five new 2‐(1‐benzofuran‐2‐yl‐2‐oxoethyl 4-(un/substitutedbenzoates 4(a–e, with the general formula of C8H5O(C=OCH2O(C=OC6H4X, X = H, Cl, CH3, OCH3 or NO2, was synthesized in high purity and good yield under mild conditions. The synthesized products 4(a–e were characterized by FTIR, 1H-, 13C- and 1H-13C HMQC NMR spectroscopic analysis and their 3D structures were confirmed by single-crystal X-ray diffraction studies. These compounds were screened for their antimicrobial and antioxidant activities. The tested compounds showed antimicrobial ability in the order of 4b < 4a < 4c < 4d < 4e and the highest potency with minimum inhibition concentration (MIC value of 125 µg/mL was observed for 4e. The results of antioxidant activities revealed the highest activity for compound 4e (32.62% ± 1.34% in diphenyl-2-picrylhydrazyl (DPPH radical scavenging, 4d (31.01% ± 4.35% in ferric reducing antioxidant power (FRAP assay and 4a (27.11% ± 1.06% in metal chelating (MC activity.

  8. Synthesis, single crystal structure and characterization of pentanitromonoformylhexaazaisowurtzitane.

    Science.gov (United States)

    Chen, Huaxiong; Chen, Shusen; Li, Lijie; Jiao, Qingze; Wei, Tianyu; Jin, Shaohua

    2010-03-15

    Pentanitromonoformylhexaazaisowurtzitane (PNMFIW) was synthesized by the nitrolysis of tetraacetyldiformylhexaazaisowurtzitane (TADFIW) in mixed nitric and sulfuric acids and structurally characterized by element analysis, FT-IR, MS and (1)H NMR. Single crystals of PNMFIW were grown from aqueous solution employing the technique of controlled evaporation. PNMFIW belongs to the orthorhombic system having four molecules in the unit cell, with space group P2(1)2(1)2(1) and the lattice parameters a=8.8000(18)A, b=12.534(2)A, and c=12.829(3)A. The calculated density reaches 1.977 g/cm(3) at 93 K, while the experimental density is 1.946 g/cm(3) at 20 degrees C. The calculated detonation velocity and pressure of PNMFIW according to the experimental density are 9195.76 m/s and 39.68G Pa, respectively. PNMFIW is insensitive compared with epsilon-HNIW through drop hammer impact sensitivity test. PMID:19913358

  9. Model Updating of Complex Structures Using the Combination of Component Mode Synthesis and Kriging Predictor

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2014-01-01

    Full Text Available Updating the structural model of complex structures is time-consuming due to the large size of the finite element model (FEM. Using conventional methods for these cases is computationally expensive or even impossible. A two-level method, which combined the Kriging predictor and the component mode synthesis (CMS technique, was proposed to ensure the successful implementing of FEM updating of large-scale structures. In the first level, the CMS was applied to build a reasonable condensed FEM of complex structures. In the second level, the Kriging predictor that was deemed as a surrogate FEM in structural dynamics was generated based on the condensed FEM. Some key issues of the application of the metamodel (surrogate FEM to FEM updating were also discussed. Finally, the effectiveness of the proposed method was demonstrated by updating the FEM of a real arch bridge with the measured modal parameters.

  10. Model updating of complex structures using the combination of component mode synthesis and Kriging predictor.

    Science.gov (United States)

    Liu, Yang; Li, Yan; Wang, Dejun; Zhang, Shaoyi

    2014-01-01

    Updating the structural model of complex structures is time-consuming due to the large size of the finite element model (FEM). Using conventional methods for these cases is computationally expensive or even impossible. A two-level method, which combined the Kriging predictor and the component mode synthesis (CMS) technique, was proposed to ensure the successful implementing of FEM updating of large-scale structures. In the first level, the CMS was applied to build a reasonable condensed FEM of complex structures. In the second level, the Kriging predictor that was deemed as a surrogate FEM in structural dynamics was generated based on the condensed FEM. Some key issues of the application of the metamodel (surrogate FEM) to FEM updating were also discussed. Finally, the effectiveness of the proposed method was demonstrated by updating the FEM of a real arch bridge with the measured modal parameters. PMID:24634612

  11. Self-assembled SnO2 micro- and nanosphere-based gas sensor thick films from an alkoxide-derived high purity aqueous colloid precursor

    Science.gov (United States)

    Kelp, G.; Tätte, T.; Pikker, S.; Mändar, H.; Rozhin, A. G.; Rauwel, P.; Vanetsev, A. S.; Gerst, A.; Merisalu, M.; Mäeorg, U.; Natali, M.; Persson, I.; Kessler, V. G.

    2016-03-01

    Tin oxide is considered to be one of the most promising semiconductor oxide materials for use as a gas sensor. However, a simple route for the controllable build-up of nanostructured, sufficiently pure and hierarchical SnO2 structures for gas sensor applications is still a challenge. In the current work, an aqueous SnO2 nanoparticulate precursor sol, which is free of organic contaminants and sorbed ions and is fully stable over time, was prepared in a highly reproducible manner from an alkoxide Sn(OR)4 just by mixing it with a large excess of pure neutral water. The precursor is formed as a separate liquid phase. The structure and purity of the precursor is revealed using XRD, SAXS, EXAFS, HRTEM imaging, FTIR, and XRF analysis. An unconventional approach for the estimation of the particle size based on the quantification of the Sn-Sn contacts in the structure was developed using EXAFS spectroscopy and verified using HRTEM. To construct sensors with a hierarchical 3D structure, we employed an unusual emulsification technique not involving any additives or surfactants, using simply the extraction of the liquid phase, water, with the help of dry butanol under ambient conditions. The originally generated crystalline but yet highly reactive nanoparticles form relatively uniform spheres through self-assembly and solidify instantly. The spheres floating in butanol were left to deposit on the surface of quartz plates bearing sputtered gold electrodes, producing ready-for-use gas sensors in the form of ca. 50 μm thick sphere-based-films. The films were dried for 24 h and calcined at 300 °C in air before use. The gas sensitivity of the structures was tested in the temperature range of 150-400 °C. The materials showed a very quickly emerging and reversible (20-30 times) increase in electrical conductivity as a response to exposure to air containing 100 ppm of H2 or CO and short (10 s) recovery times when the gas flow was stopped.Tin oxide is considered to be one of the

  12. Synthesis and structure of NaNbO3 ceramic powders in ultrahigh pressure field

    Institute of Scientific and Technical Information of China (English)

    CAO; MingHe; TIAN; Wei; LI; MingFa; SUN; WenHua; HU; MingJi; LIU; HanXing

    2007-01-01

    The NaNbO3 powders were synthesized and their crystal structure changes were analyzed by ultrahigh pressure up to 6 GPa. The results indicate that the pure NaNbO3 powders can be synthesized at 300℃ under a pressure of 4 GPa, to significantly restrain the Na element volatilization compared with the traditional synthesis method. It is found that the crystal structure of synthesized NaNbO3 changes from low symmetry to high symmetry with the increase of the pressure.

  13. Synthesis, phase stability, structural and physical properties of 11-type iron chalcogenides

    OpenAIRE

    Rößler, Sahana; Koz, Cevriye; Wirth, Steffen; Schwarz, Ulrich

    2016-01-01

    This article reviews recent experimental investigations on two binary Fe-chalcogenides: FeSe and Fe$_{1+y}$Te. The main focus is on synthesis, single crystal growth, chemical composition, as well as on the effect of excess iron on structural, magnetic, and transport properties of these materials. The structurally simplest Fe-based superconductor Fe$_{1+x}$Se with a critical temperature $T_c \\approx$ 8.5 K undergoes a tetragonal to orthorhombic phase transition at a temperature $T_s \\approx$ 8...

  14. Synthesis and Molecular Structure of Bis-Ferrocene-Containing Acyl Thiourea Derivatives

    Institute of Scientific and Technical Information of China (English)

    XU Yan; FU Yong; RAN Chun-Ling; SONG Mao-Ping

    2003-01-01

    @@ Ferrocene is a compound with excellent stability. In addition, it has very favourable electrochemical properties. So the synthesis, structure, electrochemistry and coordination behaviors of ferrocene-derivatives have attracted considerable attention in recent years.[1,2] Electrondonating atoms such as N, S, O in the derivatives are known for their coordination particularly with transition metals. [3] Two new bis-ferrocene-containing acyl thiourea derivatives are synthesized. The derivatives are confirmed by IR spectrum, 1H NMR and elemental analysis. These compoundshave many electrondonating atoms and two ferrocenes. The structure of one compound is shown below. The study onelectrochemistry and coordination behaviors is in the progress.

  15. Synthesis and structure analysis of aluminum doped zinc oxide powders

    Institute of Scientific and Technical Information of China (English)

    NIE DengPan; XUE Tao; ZHANG Yu; LI XiangJun

    2008-01-01

    Hexagonal Al-doped zinc oxide (ZnO) powders with a nominal composition of Zn1-xAlxO (0≤x≤0.028) were synthesized by the co-precipitation method. The contents of the Al element in the samples were measured by the inductively coupled plasma-optical emission spectroscopy (ICP-OES) technique. The structures of the Zn1-xAlxO (0≤x≤0.028) compounds calcined at 1000 and 1200℃ have been deter-mined using the Rietveld full-profile analysis method. Rietveld refinements of the diffraction data indi-cated that the addition of Al initially has a considerably positive effect on the decreasing of the lattice parameters a and c of Zn1-xAlxO, but the effect becomes very slight and even negative with the further increase of the Al content. The solid solubility limit of Al in ZnO (mole fraction y) is 2.21%, resulting in Zn0.978Al0.22O. It seems that when the Al content is excessive, Al prefers to form a ZnAl2O4 compound with ZnO, but not to incorporate into the ZnO lattice to occupy the Zn2+ cites. Two phases, [ZnO] (or Al-doped ZnO) and [ZnAl2O4], are obviously segregated in Zn1-xAlxO while the value of x is larger than 0.024. The UV-Vis absorption spectra show that the Al-doped ZnO exhibits a red-shift in the absorption edge without reduced transmission compared with pure ZnO, which also confirms that Al ions enter the ZnO lattice and form a Zn1-xAlxO solid solution.

  16. Synthesis and structure analysis of aluminum doped zinc oxide powders

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Hexagonal Al-doped zinc oxide (ZnO) powders with a nominal composition of Zn1-xAlxO (0≤x≤0.028) were synthesized by the co-precipitation method. The contents of the Al element in the samples were measured by the inductively coupled plasma-optical emission spectroscopy (ICP-OES) technique. The structures of the Zn1-xAlxO (0≤x≤0.028) compounds calcined at 1000 and 1200℃ have been deter- mined using the Rietveld full-profile analysis method. Rietveld refinements of the diffraction data indi- cated that the addition of Al initially has a considerably positive effect on the decreasing of the lattice parameters a and c of Zn1-xAlxO, but the effect becomes very slight and even negative with the further increase of the Al content. The solid solubility limit of Al in ZnO (mole fraction y) is 2.2l%, resulting in Zn0.978Al0.22O. It seems that when the Al content is excessive, Al prefers to form a ZnAl2O4 compound with ZnO, but not to incorporate into the ZnO lattice to occupy the Zn2+ cites. Two phases, [ZnO] (or Al-doped ZnO) and [ZnAl2O4], are obviously segregated in Zn1-xAlxO while the value of x is larger than 0.024. The UV-Vis absorption spectra show that the Al-doped ZnO exhibits a red-shift in the absorption edge without reduced transmission compared with pure ZnO, which also confirms that Al ions enter the ZnO lattice and form a Zn1-xAlxO solid solution.

  17. [Cloning of structural genes involved in riboflavin synthesis of the yeast Candida famata].

    Science.gov (United States)

    Dmytruk, K V; Abbas, C A; Voronovsky, A Y; Kshanovska, B V; Sybirna, K A; Sybirny, A A

    2004-01-01

    The riboflavin overproducing mutants of the flavinogenic yeast Candida famata isolated by conventional selection methods are used for the industrial production of vitamin B2. Recently, a transformation system was developed for C. famata using the leu2 mutant as a recipient strain and Saccharomyces cerevislae LEU2 gene as a selective marker. In this paper the cloning of C. famata genes for riboflavin synthesis on the basis of developed transformation system for this yeast species is described. Riboflavin autotrophic mutants were isolated from a previously selected C. famata leu2 strain. C. famata genomic DNA library was constructed and used for cloning of the corresponding structural genes for riboflavin synthesis by complementation of the growth defects on a medium without leucine and riboflavin. As a result, the DNA fragments harboring genes RIB1, RIB2, RIB5, RIB6 and RIB7 encoding GTP cyclohydrolase, reductase, dimethylribityllumazine synthase, dihydroxybutanone phosphate synthase and riboflavin synthase, were isolated and subsequently subcloned to the smallest possible fragments. The plasmids with these genes successfully complemented riboflavin auxotrophies of the corresponding mutants of another flavinogenic yeast Pichia guilliermondii. This suggested that C. famata structural genes for riboflavin synthesis and not some of the supressor genes were cloned. PMID:15909421

  18. Precursor Mediated Synthesis of Nanostructured Silicas: From Precursor-Surfactant Ion Pairs to Structured Materials

    Directory of Open Access Journals (Sweden)

    Peter Hesemann

    2014-04-01

    Full Text Available The synthesis of nanostructured anionic-surfactant-templated mesoporous silica (AMS recently appeared as a new strategy for the formation of nanostructured silica based materials. This method is based on the use of anionic surfactants together with a co-structure-directing agent (CSDA, mostly a silylated ammonium precursor. The presence of this CSDA is necessary in order to create ionic interactions between template and silica forming phases and to ensure sufficient affinity between the two phases. This synthetic strategy was for the first time applied in view of the synthesis of surface functionalized silica bearing ammonium groups and was then extended on the formation of materials functionalized with anionic carboxylate and bifunctional amine-carboxylate groups. In the field of silica hybrid materials, the “anionic templating” strategy has recently been applied for the synthesis of silica hybrid materials from cationic precursors. Starting from di- or oligosilylated imidazolium and ammonium precursors, only template directed hydrolysis-polycondensation reactions involving complementary anionic surfactants allowed accessing structured ionosilica hybrid materials. The mechanistic particularity of this approach resides in the formation of precursor-surfactant ion pairs in the hydrolysis-polycondensation mixture. This review gives a systematic overview over the various types of materials accessed from this cooperative ionic templating approach and highlights the high potential of this original strategy for the formation of nanostructured silica based materials which appears as a complementary strategy to conventional soft templating approaches.

  19. Synthesis of structural/control systems robust with respect to design variable tolerances

    Science.gov (United States)

    Thomas, H. L.; Schmit, L. A.

    1991-01-01

    A methodology is presented for the synthesis of control augmented structures which can be modeled as an assemblage of beam, truss, and nonstructural mass elements augmented by a robust noncollocated direct output feedback control system. The control system is robust in the sense that it can tolerate manufacturing and realization errors. The robust control system is synthesized using a constraint buffering technique in conjunction with the approximation concepts approach to system synthesis. All of the design constraints on the system, including the dynamic stability, are buffered by a nonlinear quantity that is a function of acceptable tolerances on the design variables and the sensitivity of the constraints to changes in these design variables. Numerical results which illustrate the effectiveness of the method presented are given.

  20. The Effects of Gravity on Combustion and Structure Formation During Combustion Synthesis in Gasless Systems

    Science.gov (United States)

    Varma, Arvind; Mukasyan, Alexander; Pelekh, Aleksey

    1997-01-01

    There have been relatively few publications examining the role of gravity during combustion synthesis (CS), mostly involving thermite systems. The main goal of this research was to study the influence of gravity on the combustion characteristics of heterogeneous gasless systems. In addition, some aspects of microstructure formation processes which occur during gasless CS were also studied. Four directions for experimental investigation have been explored: (1) the influence of gravity force on the characteristic features of heterogeneous combustion wave propagation (average velocity, instantaneous velocities, shape of combustion front); (2) the combustion of highly porous mixtures (with porosity greater than that for loose powders), which cannot be obtained in normal gravity; (3) the effect of gravity on sample expansion during combustion, in order to produce highly porous materials under microgravity conditions; and (4) the effect of gravity on the structure formation mechanism during the combustion synthesis of poreless composite materials.

  1. Green synthesis of ZnO nanoparticles by Aspalathus linearis: Structural & optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Diallo, A.; Ngom, B.D. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, PO Box 722, Somerset West, Western Cape (South Africa); Park, E. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, PO Box 722, Somerset West, Western Cape (South Africa); Nelson Mandela African Institute for Science & Technology, Arusha (Tanzania, United Republic of); Maaza, M., E-mail: Maaza@tlabs.ac.za [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, PO Box 722, Somerset West, Western Cape (South Africa)

    2015-10-15

    This contribution reports for the 1st time on the synthesis and the main physical properties of ZnO nanoparticles synthesized by an entirely green physical-chemistral process using Aspalathus linearis's natural extract as an efficient reduction/oxidizing agent. Their structural and optical properties by electron microscopy, X-rays diffraction, Raman and X-rays photoemission spectroscopies as well as room temperature photoluminescence are reported. - Highlights: • 1st time report on synthesis of ZnO nanoparticles by a green process via Aspalathus linearis extract. • A. linearis's natural extract was used as an effective reduction/oxidizing agent. • Wurtzite nature of ZnO nanoparticles was confirmed via XRD, Raman, XPS and PL.

  2. Green synthesis of ZnO nanoparticles by Aspalathus linearis: Structural & optical properties

    International Nuclear Information System (INIS)

    This contribution reports for the 1st time on the synthesis and the main physical properties of ZnO nanoparticles synthesized by an entirely green physical-chemistral process using Aspalathus linearis's natural extract as an efficient reduction/oxidizing agent. Their structural and optical properties by electron microscopy, X-rays diffraction, Raman and X-rays photoemission spectroscopies as well as room temperature photoluminescence are reported. - Highlights: • 1st time report on synthesis of ZnO nanoparticles by a green process via Aspalathus linearis extract. • A. linearis's natural extract was used as an effective reduction/oxidizing agent. • Wurtzite nature of ZnO nanoparticles was confirmed via XRD, Raman, XPS and PL

  3. Mu-Synthesis robust control of 3D bar structure vibration using piezo-stack actuators

    Science.gov (United States)

    Mystkowski, Arkadiusz; Koszewnik, Andrzej Piotr

    2016-10-01

    This paper presents an idea for the Mu-Synthesis robust control of 3D bar structure vibration with using a piezo-stack actuators. A model of the 3D bar structure with uncertain parameters is presented as multi-input multi-output (MIMO) dynamics. Nominal stability and nominal performances of the open-loop 3D bar structure dynamic model is developed. The uncertain model-based robust controller is derived due to voltage control signal saturation and selected parameter perturbations. The robust control performances and robustness of the system due to uncertainties influence is evaluated by using singular values and a small gain theorem. Finally, simulation investigations and experimental results shown that system response of the 3D bar structure dynamic model with taken into account perturbed parameters met desired robust stability and system limits. The proposed robust controller ensures a good dynamics of the closed-loop system, robustness, and vibration attenuation.

  4. Synthesis of regional crust and upper-mantle structure from seismic and gravity data

    Science.gov (United States)

    Alexander, S. S.; Lavin, P. M.

    1979-01-01

    Available seismic and ground based gravity data are combined to infer the three dimensional crust and upper mantle structure in selected regions. This synthesis and interpretation proceeds from large-scale average models suitable for early comparison with high-altitude satellite potential field data to more detailed delineation of structural boundaries and other variations that may be significant in natural resource assessment. Seismic and ground based gravity data are the primary focal point, but other relevant information (e.g. magnetic field, heat flow, Landsat imagery, geodetic leveling, and natural resources maps) is used to constrain the structure inferred and to assist in defining structural domains and boundaries. The seismic data consists of regional refraction lines, limited reflection coverage, surface wave dispersion, teleseismic P and S wave delay times, anelastic absorption, and regional seismicity patterns. The gravity data base consists of available point gravity determinations for the areas considered.

  5. Carborane-containing urea-based inhibitors of glutamate carboxypeptidase II: Synthesis and structural characterization.

    Science.gov (United States)

    Youn, Sihyun; Kim, Kyung Im; Ptacek, Jakub; Ok, Kiwon; Novakova, Zora; Kim, YunHye; Koo, JaeHyung; Barinka, Cyril; Byun, Youngjoo

    2015-11-15

    Glutamate carboxypeptidase II (GCPII) is a zinc metalloprotease on the surface of astrocytes which cleaves N-acetylaspartylglutamate to release N-acetylaspartate and glutamate. GCPII inhibitors can decrease glutamate concentration and play a protective role against apoptosis or degradation of brain neurons. Herein, we report the synthesis and structural analysis of novel carborane-based GCPII inhibitors. We determined the X-ray crystal structure of GCPII in complex with a carborane-containing inhibitor at 1.79Å resolution. The X-ray analysis revealed that the bulky closo-carborane cluster is located in the spacious entrance funnel region of GCPII, indicating that the carborane cluster can be further structurally modified to identify promising lead structures of novel GCPII inhibitors.

  6. Synthesis and X-ray Crystal Structure of a New Molecular Clip

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The synthesis and X-ray crystal structure of a new molecular clip 2 was reported.It (C24H24N4O2, Mr = 400.47) crystallizes in the space group C2/c with a = 15.587(2), b =8.5805(12), c = 15.259(2)(A),β= 102.448(3)°, V = 1992.9 (5)(A)3, Z= 4, Dc = 1.335 g/cm3,μ= 0.087mm-1 and F(000) = 848.It remains monomeric in the crystal and a tape-like structure is formed in the crystal structure of molecular clip.The most unusual structural feature of 2 is the boat conformation of its cyclohexyl ring imposed by the ring fusion at C(9)-C(9a).

  7. Carborane-containing urea-based inhibitors of glutamate carboxypeptidase II: Synthesis and structural characterization.

    Science.gov (United States)

    Youn, Sihyun; Kim, Kyung Im; Ptacek, Jakub; Ok, Kiwon; Novakova, Zora; Kim, YunHye; Koo, JaeHyung; Barinka, Cyril; Byun, Youngjoo

    2015-11-15

    Glutamate carboxypeptidase II (GCPII) is a zinc metalloprotease on the surface of astrocytes which cleaves N-acetylaspartylglutamate to release N-acetylaspartate and glutamate. GCPII inhibitors can decrease glutamate concentration and play a protective role against apoptosis or degradation of brain neurons. Herein, we report the synthesis and structural analysis of novel carborane-based GCPII inhibitors. We determined the X-ray crystal structure of GCPII in complex with a carborane-containing inhibitor at 1.79Å resolution. The X-ray analysis revealed that the bulky closo-carborane cluster is located in the spacious entrance funnel region of GCPII, indicating that the carborane cluster can be further structurally modified to identify promising lead structures of novel GCPII inhibitors. PMID:26459214

  8. Effect of Alcohol Structure on the Optimum Condition for Novozym 435-Catalyzed Synthesis of Adipate Esters

    Directory of Open Access Journals (Sweden)

    Mohd Basyaruddin Abdul Rahman

    2011-01-01

    Full Text Available Immobilized Candida antarctica lipase B, Novozym 435, was used as the biocatalyst in the esterification of adipic acid with four different isomers of butanol (n-butanol, sec-butanol, iso-butanol, and tert-butanol. Optimum conditions for the synthesis of adipate esters were obtained using response surface methodology approach with a four-factor-five-level central composite design concerning important reaction parameters which include time, temperature, substrate molar ratio, and amount of enzyme. Reactions under optimized conditions has yielded a high percentage of esterification (>96% for n-butanol, iso-butanol, and sec-butanol, indicating that extent of esterification is independent of the alcohol structure for primary and secondary alcohols at the optimum conditions. Minimum reaction time (135 min for achieving maximum ester yield was obtained for iso-butanol. The required time for attaining maximum yield and also the initial rates in the synthesis of di-n-butyl and di-sec-butyl adipate were nearly the same. Immobilized Candida antarctica lipase B was also capable of esterifying tert-butanol with a maximum yield of 39.1%. The enzyme is highly efficient biocatalyst for the synthesis of adipate esters by offering a simple production process and a high esterification yield.

  9. Synthesis of Porous and Mechanically Compliant Carbon Aerogels Using Conductive and Structural Additives

    Directory of Open Access Journals (Sweden)

    Carlos Macias

    2016-01-01

    Full Text Available We report the synthesis of conductive and mechanically compliant monolithic carbon aerogels prepared by sol-gel polycondensation of melamine-resorcinol-formaldehyde (MRF mixtures by incorporating diatomite and carbon black additives. The resulting aerogels composites displayed a well-developed porous structure, confirming that the polymerization of the precursors is not impeded in the presence of either additive. The aerogels retained the porous structure after etching off the siliceous additive, indicating adequate cross-linking of the MRF reactants. However, the presence of diatomite caused a significant fall in the pore volumes, accompanied by coarsening of the average pore size (predominance of large mesopores and macropores. The diatomite also prevented structural shrinkage and deformation of the as-prepared monoliths upon densification by carbonization, even after removal of the siliceous framework. The rigid pristine aerogels became more flexible upon incorporation of the diatomite, favoring implementation of binderless monolithic aerogel electrodes.

  10. Synthesis and Crystal Structure of 2’-Se-modified guanosine Containing DNA

    Energy Technology Data Exchange (ETDEWEB)

    Salon, J.; Sheng, J; Gan, J; Huang, Z

    2010-01-01

    Selenium modification of nucleic acids is of great importance in X-ray crystal structure determination and functional study of nucleic acids. Herein, we describe a convenient synthesis of a new building block, the 2{prime}-SeMe-modified guanosine (G{sub Se}) phosphoramidite, and report the first incorporation of the 2{prime}-Se-G moiety into DNA. The X-ray crystal structure of the 2{prime}-Se-modified octamer DNA (5{prime}-GTG{sub Se}TACAC-3{prime}) was determined at a resolution of 1.20 {angstrom}. We also found that the 2{prime}-Se modification points to the minor groove and that the modified and native structures are virtually identical. Furthermore, we observed that the 2{prime}-Se-G modification can significantly facilitate the crystal growth with respect to the corresponding native DNA.

  11. Metal-organic frameworks: structure, properties, methods of synthesis and characterization

    Science.gov (United States)

    Butova, V. V.; Soldatov, M. A.; Guda, A. A.; Lomachenko, K. A.; Lamberti, C.

    2016-03-01

    This review deals with key methods of synthesis and characterization of metal-organic frameworks (MOFs). The modular structure affords a wide variety of MOFs with different active metal sites and organic linkers. These compounds represent a new stage of development of porous materials in which the pore size and the active site structure can be modified within wide limits. The set of experimental methods considered in this review is sufficient for studying the short-range and long-range order of the MOF crystal structure, determining the morphology of samples and elucidating the processes that occur at the active metal site in the course of chemical reactions. The interest in metal-organic frameworks results, first of all, from their numerous possible applications, ranging from gas separation and storage to chemical reactions within the pores. The bibliography includes 362 references.

  12. Carbonyl Diisocyanate CO(NCO)2: Synthesis and Structures in Solid State and Gas Phase.

    Science.gov (United States)

    Klapötke, Thomas M; Krumm, Burkhard; Rest, Sebastian; Scharf, Regina; Schwabedissen, Jan; Stammler, Hans-Georg; Mitzel, Norbert W

    2016-07-01

    A modified synthesis for carbonyl diisocyanate, CO(NCO)2, starting from trichloroisocyanuric acid and diphosgene is described. In addition to the previously reported (13)C NMR resonances, the (15)N NMR shift is determined for the first time. The structure in the solid state was determined by X-ray diffraction (XRD) on in situ grown crystals, that in the gas phase was experimentally determined by electron diffraction (GED) and for single molecules theoretically by quantum-chemical calculations. The structures are compared and discussed with related systems. Quantum-chemical calculations as well as GED and XRD prove syn-syn to be the conformation of lowest energy. In quantum-chemical calculations and GED the presence of a syn-anti conformer was confirmed and the structure of this conformer was determined.

  13. Design, synthesis and structure of new potential electrochemically active boronic acid-based glucose sensors

    DEFF Research Database (Denmark)

    Norrild, Jens Chr.; Søtofte, Inger

    2002-01-01

    In the course of our investigations on new boronic acid based carbohydrate sensors three new boronic acids 3, 7 and 11 containing a ferrocene moiety were synthesised. Their design includes an intramolecular B-N bonding motif in order to facilitate binding at physiological pH. We report...... the synthesis of the compounds and our investigations on glucose complexation as studied by C-13 NMR spectroscopy. The crystal structure of 2,4,6-tris[2-(N-ferrocenylmethyl-N-methylaminomethyl) phenyl] boroxin (13) (boroxin of boronic acid 3) (boroxin = cyclotriboroxane) was obtained and compared...... with structures obtained of 2,4,6-tris[2-(N,N-dimethylaminomethyl)phenyl]boroxin (14) and 2,2-dimethyl-1,3-diyl[2-(N,N-dimethylaminomethyl)phenyl]boronate (15). The structure of 13 shows the existence of intramolecular B-N bonds in the solid phase....

  14. Synthesis and Quantitative Structure-Property Relationships of Side Chain-Modified Hyodeoxycholic Acid Derivatives

    Directory of Open Access Journals (Sweden)

    Antimo Gioiello

    2013-08-01

    Full Text Available Bile acids have emerged as versatile signalling compounds of a complex network of nuclear and membrane receptors regulating various endocrine and paracrine functions. The elucidation of the interconnection between the biological pathways under the bile acid control and manifestations of hepatic and metabolic diseases have extended the scope of this class of steroids for in vivo investigations. In this framework, the design and synthesis of novel biliary derivatives able to modulate a specific receptor requires a deep understanding of both structure-activity and structure-property relationships of bile acids. In this paper, we report the preparation and the critical micellization concentration evaluation of a series of hyodeoxycholic acid derivatives characterized by a diverse side chain length and by the presence of a methyl group at the alpha position with respect to the terminal carboxylic acid moiety. The data collected are instrumental to extend on a quantitative basis, the knowledge of the current structure-property relationships of bile acids and will be fruitful, in combination with models of receptor activity, to design and prioritize the synthesis of novel pharmacokinetically suitable ligands useful in the validation of bile acid-responsive receptors as therapeutic targets.

  15. Synthesis, spectroscopic characterizations, crystal structures and DFT studies of nalidixic acid carbonyl hydrazones derivatives

    Science.gov (United States)

    Bergamini, F. R. G.; Ribeiro, M. A.; Lancellotti, M.; Machado, D.; Miranda, P. C. M. L.; Cuin, A.; Formiga, A. L. B.; Corbi, P. P.

    2016-09-01

    This article describes the synthesis and characterization of the 1-ethyl-7-methyl-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carbohydrazide (hzd) and six carbonyl hydrazones derivatives of the nalidixic with 1H-pyrrol-2-ylmethylidene (hpyrr), 1H-imidazol-2-ylmethylidene (h2imi), pyridin-2-ylmethylidene (h2py), pyridin-3-ylmethylidene (h3py), pyridin-4-ylmethylidene(h4py) and (2-hydroxyphenyl)methylidene (hsali). The carbonyl hydrazones were characterized by elemental and ESI-QTOF-MS analyses, IR and detailed NMR spectroscopic measurements. The 2D NMR experiments allowed the unambiguous assignment of the hydrogen, carbon and nitrogen atoms, which have not been reported for nalidixic acid carbonyl hydrazone derivatives so far. Crystal structures of hzd and the new carbonyl hydrazones h2imi, hpyrr and h3py were determined by X-ray diffraction studies. Although the synthesis of hzd was reported decades ago, the hzd crystal structure have not been reported yet. Geometric optimizations of all the characterized structures were performed with the aid of DFT studies. Despite the fact that the hydrazones with 2-pyridine carboxylic acid (h2py) and salicyl aldehyde (hsali) were already reported by literature, a detailed spectroscopic study followed by DFT studies are also reported for such compounds in this manuscript. Antimicrobial studies of the compounds are also presented.

  16. Zr-based metal-organic frameworks: design, synthesis, structure, and applications.

    Science.gov (United States)

    Bai, Yan; Dou, Yibo; Xie, Lin-Hua; Rutledge, William; Li, Jian-Rong; Zhou, Hong-Cai

    2016-04-21

    Among the large family of metal-organic frameworks (MOFs), Zr-based MOFs, which exhibit rich structure types, outstanding stability, intriguing properties and functions, are foreseen as one of the most promising MOF materials for practical applications. Although this specific type of MOF is still in its early stage of development, significant progress has been made in recent years. Herein, advances in Zr-MOFs since 2008 are summarized and reviewed from three aspects: design and synthesis, structure, and applications. Four synthesis strategies implemented in building and/or modifying Zr-MOFs as well as their scale-up preparation under green and industrially feasible conditions are illustrated first. Zr-MOFs with various structural types are then classified and discussed in terms of different Zr-based secondary building units and organic ligands. Finally, applications of Zr-MOFs in catalysis, molecule adsorption and separation, drug delivery, and fluorescence sensing, and as porous carriers are highlighted. Such a review based on a specific type of MOF is expected to provide guidance for the in-depth investigation of MOFs towards practical applications.

  17. Regulation of genes involved in cell wall synthesis and structure during Ustilago maydis dimorphism.

    Science.gov (United States)

    Robledo-Briones, Mariana; Ruiz-Herrera, José

    2013-02-01

    The cell wall is the structure that provides the shape to fungal cells and protects them from the difference in osmotic pressure existing between the cytosol and the external medium. Accordingly, changes in structure and composition of the fungal wall must occur during cell differentiation, including the dimorphic transition of fungi. We analyzed, by use of microarrays, the transcriptional regulation of the 639 genes identified to be involved in cell wall synthesis and structure plus the secretome of the Basidiomycota species Ustilago maydis during its dimorphic transition induced by a change in pH. Of these, 189 were differentially expressed during the process, and using as control two monomorphic mutants, one yeast like and the other mycelium constitutive, 66 genes specific of dimorphism were identified. Most of these genes were up-regulated in the mycelial phase. These included CHS genes, genes involved in β-1,6-glucan synthesis, N-glycosylation, and proteins containing a residue of glycosylphosphatidylinositol, and a number of genes from the secretome. The possible significance of these data on cell wall plasticity is discussed.

  18. The synthesis: Structure relationship in the ZnO-Cr2O3 system

    Directory of Open Access Journals (Sweden)

    Mančić Lidija T.

    2004-01-01

    Full Text Available In this work the development of the spinel phase in the ZnO-Cr2O3 system was discussed from the viewpoint of the synthesis-structure relationship. The nanostructure evolution in particles obtained either via solution-based (spray pyrolysis or solid-state (mechanical activation synthesis procedures were investigated by XRD analysis. A detailed structural analysis of the spinel phase lattice parameters, average primary crystallite sizes and micro strains were performed in accordance with a procedure based on the Koalariet-Xfit program. Due to the importance of spinel-phase cat ion distribution for chemical and physical properties, a study of the site occupation factors, i.e. changes in the stoichiometric, of ZnCr2O4 spinals was undertaken. The calculation based on atomistic methods for the description of both perfect and defect spinel ZnCr2O4 crystal lattices has been applied and the presence of individual structural defects was determined.

  19. Carbon Nanotubes Advanced Topics in the Synthesis, Structure, Properties and Applications

    CERN Document Server

    Jorio, Ado; Dresselhaus, Mildred S

    2008-01-01

    The carbon nanotubes field has evolved substantially since the publication of the bestseller "Carbon Nanotubes: Synthesis, Structure, Properties and Applications". The present volume builds on the generic aspects of the aforementioned book, which emphasizes the fundamentals, with the new volume emphasizing areas that have grown rapidly since the first volume, guiding future directions where research is needed and highlighting applications. The volume also includes an emphasis on areas like graphene, other carbon-like and other tube-like materials because these fields are likely to affect and influence developments in nanotubes in the next 5 years.

  20. Synthesis and crystal structure determination of Pb2[UO2][TeO3]3

    International Nuclear Information System (INIS)

    Single crystals of Pb2[UO2][TeO3]3 were obtained by hydrothermal synthesis. The crystal data are reported. The structure was determined from X-ray intensities measured on a two-circle diffractometer and was refined for 2566 independent observed reflections to R = 0.059. It can be described as built up by [[UO2][TeO3]3]4sup(n)-sub(n) sheets parallel to (010) which are connected by lead atoms in irregular coordination. (orig./GSCH)

  1. Simple synthesis and biological evaluation of flocoumafen and its structural isomers

    Indian Academy of Sciences (India)

    Jae-Chul Jung; Soyong Jang; Seikwan Oh; Oee-Sook Park

    2010-11-01

    Simple synthesis and biological properties of flocoumafen 1 and its structural isomers are described. The key synthetic strategies involve Knoevenagel condensation, Grignard reaction, intramolecular ring cyclization and coupling reaction. Flocoumafen 1 was easily separated into cis and trans forms using flash column chromatography. They were then evaluated for suppression of LPS-induced NO generation and anti-excitotoxicity in vitro. It was found that the trans-flocoumafen was potent suppressor of NO generation with the concentration of 10 M in vitro, while no significant effect for neurotoxicity in cultured cortical neurons.

  2. SYNTHESIS OF PARALLEL MECHANISM BASED ROBOT MANIPULATORS FROM STRUCTURAL POINT OF VIEW

    Directory of Open Access Journals (Sweden)

    DR. JAGDISH M. PRAJAPATI

    2011-02-01

    Full Text Available Because of their potential merits, the parallel mechanisms are more popular than serial mechanisms based robot manipulators in specific applications. One of the ways of classifying the parallel manipulatorsis according to their platform types and connection between them. Methods for designing different types of parallel manipulators with one or more platforms are presented. The classification of parallel mechanism based manipulators and synthesis of them from structural point of view are presented in this paper. The step by step procedure is presented with help of examples.

  3. High-Pressure Synthesis, Crystal Structure and Physical Properties of Gallium Oxonitride

    OpenAIRE

    Zvoriste, Carmen

    2011-01-01

    This thesis is concerned with the synthesis and properties of the high-pressure, high-temperature (HP/HT) phase of gallium oxonitride, which has a spinel-type structure. Since this material is an analogue of γ-alon (spinel-aluminium oxonitride), which is known to be an important material with a wide range of applications, the spinelstructured gallium oxonitride is an attractive material with the potential for tailoring its composition and tuning its electronic properties, i.e. for optoelectro...

  4. Structured singular value synthesis based steam generator water level controller design

    International Nuclear Information System (INIS)

    An uncertainty kinetic model for valve position of feed water to steam generator water level plant was built which can express parameter perturbation and unmodeled dynamic due to operation condition change of steam generator and feed water pump. Robust controller was designed based on structured singular value synthesis method. Robust stability of the water control system can be guaranteed under parameter perturbation and unmodeled dynamic, and robust performance can be acquired via suitable performance weight function. Simulation results show that good control performances are obtained under all combinations of steam generator operation condition and feed water pump operation condition. (authors)

  5. Synthesis, characterization, and crystal structure of 2-iodo-3,4,5-trimethoxybenzoic acid

    Science.gov (United States)

    Kolev, Iliyan N.; Petrova, Svetlana P.; Nikolova, Rositsa P.; Dimowa, Louiza T.; Shivachev, Boris L.

    2013-02-01

    This work describes the synthesis of 2-iodo-3,4,5-trimethoxybenzoic acid. The combination of iodine and silver trifluoroacetate (AgTFA) reagents was used successfully for the iodination of 3,4,5-trimetoxybenzoic acid. To improve the efficiency of the synthetic process a significant modification on the experimental design was also performed. The main structural features of the obtained aryl iodide were investigated by a single crystal X-ray diffraction analysis, FTIR, 1H and 13C NMR spectroscopy.

  6. Structural organization of films based on polyaniline/polysulfonic acid complexes depending on the synthesis method

    International Nuclear Information System (INIS)

    The optical properties and morphology of complexes based on polyaniline (PANI) and poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS), depending on their synthesis conditions, have been characterized by UV-visible spectroscopy and atomic force microscopy. The dependence of the electron absorption spectra of PANI/PAMPS complexes and the surface topography of their films on the initiation way of PANI formation (chemical and enzymatic) and the use of promoters of aniline polymerization has been investigated. The aniline polymerization kinetics with and without polymerization promoters has been studied. All PANI/PAMPS complexes are found to have a nanocomposite time-stable structure.

  7. Synthesis of Pt Nanoparticles in Water-in-Oil Microemulsion: Effect of HCl on Their Surface Structure

    OpenAIRE

    Martínez-Rodríguez, Roberto A.; Vidal-Iglesias, Francisco J.; Solla-Gullón, José; Cabrera, Carlos R.; Juan M Feliu

    2014-01-01

    The synthesis of shape-controlled nanoparticles is currently a hot research topic. However, from an applied point of view, there is still a lack of easy, cheap, and scalable methodologies. In this communication we report, for the first time, the synthesis of cubic platinum nanoparticles with a very high yield using a water-in-oil microemulsion method, which unlike others, such as the colloidal method, fulfills the previous requirements. This shape/surface structure control is determined by th...

  8. Synthesis and characterization of nitroaromatic peptoids: fine tuning peptoid secondary structure through monomer position and functionality.

    Science.gov (United States)

    Fowler, Sarah A; Luechapanichkul, Rinrada; Blackwell, Helen E

    2009-02-20

    N-substituted glycine oligomers, or peptoids, have emerged as an important class of foldamers for the study of biomolecular interactions and for potential use as therapeutic agents. However, the design of peptoids with well-defined conformations a priori remains a formidable challenge. New approaches are required to address this problem, and the systematic study of the role of individual monomer units in the global peptoid folding process represents one strategy. Here, we report our efforts toward this approach through the design, synthesis, and characterization of peptoids containing nitroaromatic monomer units. This work required the synthesis of a new chiral amine building block, (S)-1-(2-nitrophenyl)ethanamine (s2ne), which could be readily installed into peptoids using standard solid-phase peptoid synthesis techniques. We designed a series of peptoid nonamers that allowed us to probe the effects of this relatively electron-deficient and sterically encumbered alpha-chiral side chain on peptoid structure, namely, the peptoid threaded loop and helix. Circular dichroism spectroscopy of the peptoids revealed that the nitroaromatic monomer has a significant effect on peptoid secondary structure. Specifically, the threaded loop structure was disrupted in a nonamer containing alternating N-(S)-1-phenylethylglycine (Nspe) and Ns2ne monomers, and the major conformation was helical instead. Indeed, placement of a single Ns2ne at the N-terminal position of (Nspe)(9) resulted in a destabilized form of the threaded loop structure relative to the homononamer (Nspe)(9). Conversely, we observed that incorporation of N-(S)-1-(4-nitrophenyl)ethylglycine (Nsnp, a p-nitro monomer) at the N-terminal position stabilized the threaded loop structure relative to (Nspe)(9). Additional experiments revealed that nitroaromatic side chains can influence peptoid nonamer folding by modulating the strength of key intramolecular hydrogen bonds in the peptoid threaded loop structure. Steric

  9. Synthesis and Characterization of Upconversion Fluorescent Yb3+, Er3+ Doped CsY2F7 Nano- and Microcrystals

    Directory of Open Access Journals (Sweden)

    Helmut Schäfer

    2009-01-01

    Full Text Available Cs Y2F7: 78%   Y3+, 20%   Yb3+, 2%   Er3+ nanocrystals with a mean diameter of approximately 8 nm were synthesized at   185°C in the high boiling organic solvent N-(2-hydroxyethyl-ethylenediamine (HEEDA using ammonium fluoride, the rare earth chlorides and a solution of caesium alkoxide of N-(2-hydroxyethyl-ethylenediamine in HEEDA. In parallel with this approach, a microwave assisted synthesis was carried out which forms nanocrystals of the same material, about 50 nm in size, in aqueous solution at 200∘C/8 bar starting from ammonium fluoride, the rare earth chlorides, and caesium fluoride. In case of the nanocrystals, derived from the HEEDA synthesis, TEM images reveal that the particles are separated but have a broad size distribution. Also an occurred heat-treatment of these nanocrystals (600∘C for 45 minutes led to bulk material which shows highly efficient light emission upon continuous wave (CW excitation at 978 nm. Besides the optical properties, the structure and the morphology of the three products were investigated by means of powder XRD and Rietveld method.

  10. Synthesis and Crystal Structures of Three Ladder Distannoxane Dimers [(PhCH2)2(Cl)SnOSn(X)(CH2Ph)2]2(X=Cl,OMe,OEt)

    Institute of Scientific and Technical Information of China (English)

    马春林; 李凤

    2003-01-01

    Three distannoxane dimers[(PhCH2)2(Cl)SnOSn(X)(CH2Ph)2]2(X=Cl,OMe,OEt)were prepared by the hydrolytic reaction of (PhCH2)2SnCl2 with sodium alkoxides.The compounds are assigned tetranuclear distannoxane structures in solid state.which contain the so-called ladder arrangement with a central planar Sn2O2 four-membered ring.The endo-and exo-cyclic Sn atoms are both five-coordinate,and have distorted trigonal bipyramidal geometries.A variety of hydrolyses of(PhCH2)2SnCl2 were performed and these dimers were characterized by IR,1H NMR spectroscopy and X-ray diffraction analysis.

  11. Polymer-virus core-shell structures prepared via co-assembly and template synthesis methods

    Institute of Scientific and Technical Information of China (English)

    SUTHIWANGCHAROEN; Nisaraporn; PREVELIGE; Peter; E.Jr

    2010-01-01

    Bionanoparticles(BNPs),consisting of virus and virus-like assemblies,have attracted much attention in the biomedical field for their applications such as imaging and targeted drug delivery,owing to their well-defined structures and well-controlled chemistries.BNPs-based core-shell structures provide a unique system for the investigation of biological interactions such as protein-protein and protein-carbohydrate interactions.However,it is still a challenge to prepare the BNPs-based core-shell structures.Herein,we describe(i) co-assembly method and(ii) template synthesis method in the development of polymer-BNPs core-shell structures.These two methods can be divided into three different systems.In system A,different polymers including poly(2-vinylpyridine)(P2VP),poly(4-vinylpyridine)(P4VP) and poly(ε-caprolactone)-block-poly(2-vinylpyridine)(PCL-b-P2VP) can form a raspberry-like structure with BNPs.In system B,polystyrene(PS) spheres end capped with free amine and BNPs can form a core-shell structure.In System C,layer-by-layer(LBL) method is used to prepare positive charged PS particles,which can be used as a template to form the core-shell structures with BNPs.These two methods may open a new way for preparing novel protein-based functional materials for potential applications in the biomedical field.

  12. Synthesis of a mixed-valent tin nitride and considerations of its possible crystal structures

    Science.gov (United States)

    Caskey, Christopher M.; Holder, Aaron; Shulda, Sarah; Christensen, Steven T.; Diercks, David; Schwartz, Craig P.; Biagioni, David; Nordlund, Dennis; Kukliansky, Alon; Natan, Amir; Prendergast, David; Orvananos, Bernardo; Sun, Wenhao; Zhang, Xiuwen; Ceder, Gerbrand; Ginley, David S.; Tumas, William; Perkins, John D.; Stevanovic, Vladan; Pylypenko, Svitlana; Lany, Stephan; Richards, Ryan M.; Zakutayev, Andriy

    2016-04-01

    Recent advances in theoretical structure prediction methods and high-throughput computational techniques are revolutionizing experimental discovery of the thermodynamically stable inorganic materials. Metastable materials represent a new frontier for these studies, since even simple binary non-ground state compounds of common elements may be awaiting discovery. However, there are significant research challenges related to non-equilibrium thin film synthesis and crystal structure predictions, such as small strained crystals in the experimental samples and energy minimization based theoretical algorithms. Here, we report on experimental synthesis and characterization, as well as theoretical first-principles calculations of a previously unreported mixed-valent binary tin nitride. Thin film experiments indicate that this novel material is N-deficient SnN with tin in the mixed ii/iv valence state and a small low-symmetry unit cell. Theoretical calculations suggest that the most likely crystal structure has the space group 2 (SG2) related to the distorted delafossite (SG166), which is nearly 0.1 eV/atom above the ground state SnN polymorph. This observation is rationalized by the structural similarity of the SnN distorted delafossite to the chemically related Sn3N4 spinel compound, which provides a fresh scientific insight into the reasons for growth of polymorphs of metastable materials. In addition to reporting on the discovery of the simple binary SnN compound, this paper illustrates a possible way of combining a wide range of advanced characterization techniques with the first-principle property calculation methods, to elucidate the most likely crystal structure of the previously unreported metastable materials.

  13. Synthesis of a mixed-valent tin nitride and considerations of its possible crystal structures.

    Science.gov (United States)

    Caskey, Christopher M; Holder, Aaron; Shulda, Sarah; Christensen, Steven T; Diercks, David; Schwartz, Craig P; Biagioni, David; Nordlund, Dennis; Kukliansky, Alon; Natan, Amir; Prendergast, David; Orvananos, Bernardo; Sun, Wenhao; Zhang, Xiuwen; Ceder, Gerbrand; Ginley, David S; Tumas, William; Perkins, John D; Stevanovic, Vladan; Pylypenko, Svitlana; Lany, Stephan; Richards, Ryan M; Zakutayev, Andriy

    2016-04-14

    Recent advances in theoretical structure prediction methods and high-throughput computational techniques are revolutionizing experimental discovery of the thermodynamically stable inorganic materials. Metastable materials represent a new frontier for these studies, since even simple binary non-ground state compounds of common elements may be awaiting discovery. However, there are significant research challenges related to non-equilibrium thin film synthesis and crystal structure predictions, such as small strained crystals in the experimental samples and energy minimization based theoretical algorithms. Here, we report on experimental synthesis and characterization, as well as theoretical first-principles calculations of a previously unreported mixed-valent binary tin nitride. Thin film experiments indicate that this novel material is N-deficient SnN with tin in the mixed ii/iv valence state and a small low-symmetry unit cell. Theoretical calculations suggest that the most likely crystal structure has the space group 2 (SG2) related to the distorted delafossite (SG166), which is nearly 0.1 eV/atom above the ground state SnN polymorph. This observation is rationalized by the structural similarity of the SnN distorted delafossite to the chemically related Sn3N4 spinel compound, which provides a fresh scientific insight into the reasons for growth of polymorphs of metastable materials. In addition to reporting on the discovery of the simple binary SnN compound, this paper illustrates a possible way of combining a wide range of advanced characterization techniques with the first-principle property calculation methods, to elucidate the most likely crystal structure of the previously unreported metastable materials. PMID:27083713

  14. Synthesis and crystal structure study of 2′-Se-adenosine-derivatized DNA

    Institute of Scientific and Technical Information of China (English)

    SALON; Jozef

    2010-01-01

    The selenium derivatization of nucleic acids is a novel and promising strategy for 3D structure determination of nucleic acids.Selenium can serve as an excellent anomalous scattering center to solve the phase problem,which is one of the two major bottlenecks in macromolecule X-ray crystallography.The other major bottleneck is crystallization.It has been demonstrated that the incorporated selenium functionality at the 2′-positions of the nucleosides and nucleotides is stable and does not cause significant structure perturbation.Furthermore,it was observed that the 2′-Se-derivatization could facilitate crystallization of oligonucleotides with fast crystal growth and high diffraction quality.Herein,we describe a convenient synthesis of the 2′-Se-adenosine phosphoramidite,and report the first synthesis and X-ray crystal structure determination of the DNA containing the 2′-Se-A derivatization.The 3D structure of 2′-Se-A-DNA decamer 5′-GTACGCGT(2′-Se-A)C-3′2 was determined at 1.75 ? resolution,the 2′-Se-functionality points to the minor groove,and the Se-modified and native structures are virtually identical.Moreover,we have observed that the 2′-Se-A modification can greatly facilitate the crystal growth with high diffraction quality.In conjunction with the crystallization facilitation by the 2′-Se-U and 2′-Se-T,this novel observation on the 2′-Se-A functionality suggests that the 2′-Se moiety is sole responsible for the crystallization facilitation and the identity of nucleobases does not influence the crystal growth significantly.

  15. A synthesis of predictions and correlation studies of the Lotung soil- structure interaction experiment

    International Nuclear Information System (INIS)

    Unnecessary conservatism is seismic design and licensing acceptance criteria is largely due to the lack of field data to validate the analytical methods used. EPRI and the Taiwan Power Company (TPC) constructed the Lotung large-scale seismic test (LSST) facility in Taiwan to collect forced-vibration and seismic response data for soil-structure interaction (SSI) methods evaluation. To date, more than 30 earthquakes have been recorded. EPRI, TPC, and NRC cosponsored a round-robin evaluation program to test the response prediction capability of the existing SSI models and analysis practices. The results were reported at a workshop in December 1987. Since then, EPRI has conducted additional post-earthquake studies to further evaluate, understand, and correlate SSI responses. The LSST results synthesis has yielded significant insights and findings with respect to the validity of SSI analysis methodologies for earthquake responses. The differences in response predictions among the commonly used SSI methodologies are due more to the modeling of the soil-structure systems than the calculation techniques. The more advanced methodologies, such as SASSI and CLASSI, generally yield better correlation results. The simple soil-spring approach and the two-dimensional FLUSH method should be used with care, considering their limitations. The synthesis of results also confirms the adequacy of the vertical wave-propagation assumption and the significance of strain-dependent soil property variations for the SSI analysis. 19 refs., 26 figs., 12 tabs

  16. A synthesis of predictions and correlation studies of the Lotung soil- structure interaction experiment

    Energy Technology Data Exchange (ETDEWEB)

    Hadjian, A.H. (Bechtel Power Corp., Norwalk, CA (United States))

    1991-10-01

    Unnecessary conservatism is seismic design and licensing acceptance criteria is largely due to the lack of field data to validate the analytical methods used. EPRI and the Taiwan Power Company (TPC) constructed the Lotung large-scale seismic test (LSST) facility in Taiwan to collect forced-vibration and seismic response data for soil-structure interaction (SSI) methods evaluation. To date, more than 30 earthquakes have been recorded. EPRI, TPC, and NRC cosponsored a round-robin evaluation program to test the response prediction capability of the existing SSI models and analysis practices. The results were reported at a workshop in December 1987. Since then, EPRI has conducted additional post-earthquake studies to further evaluate, understand, and correlate SSI responses. The LSST results synthesis has yielded significant insights and findings with respect to the validity of SSI analysis methodologies for earthquake responses. The differences in response predictions among the commonly used SSI methodologies are due more to the modeling of the soil-structure systems than the calculation techniques. The more advanced methodologies, such as SASSI and CLASSI, generally yield better correlation results. The simple soil-spring approach and the two-dimensional FLUSH method should be used with care, considering their limitations. The synthesis of results also confirms the adequacy of the vertical wave-propagation assumption and the significance of strain-dependent soil property variations for the SSI analysis. 19 refs., 26 figs., 12 tabs.

  17. Controlled synthesis of organic nanophotonic materials with specific structures and compositions.

    Science.gov (United States)

    Cui, Qiu Hong; Zhao, Yong Sheng; Yao, Jiannian

    2014-10-29

    Organic nanomaterials have drawn great interest for their potential applications in high-speed miniaturized photonic integration due to their high photoluminescence quantum efficiency, structural processability, ultrafast photoresponse, and excellent property engineering. Based on the rational design on morphological and componential levels, a series of organic nanomaterials have been controllably synthesized in recent years, and their excitonic/photonic behaviors has been fine-tuned to steer the light flow for specific optical applications. This review presents a comprehensive summary of recent breakthroughs in the controlled synthesis of organic nanomaterials with specific structures and compositions, whose tunable photonic properties would provide a novel platform for multifunctional applications. First, we give a general overview of the tailored construction of novel nanostructures with various photonic properties. Then, we summarize the design and controllable synthesis of composite materials for the modulation of their functionalities. Subsequently, special emphasis is put on the fabrication of complex nanostructures towards wide applications in isolated photonic devices. We conclude with our personal viewpoints on the development directions in the novel design and controllable construction of organic nanomaterials for future applications in highly integrated photonic devices and chips.

  18. Synthesis of magnesium- and manganese-doped hydroxyapatite structures assisted by the simultaneous incorporation of strontium.

    Science.gov (United States)

    Moreira, Mirna Pereira; de Almeida Soares, Gloria Dulce; Dentzer, Joseph; Anselme, Karine; de Sena, Lídia Ágata; Kuznetsov, Alexei; dos Santos, Euler Araujo

    2016-04-01

    Samples of crystalline hydroxyapatite (HA) with and without the addition of individual Mg(2+), Mn(2+) and Sr(2+) ions and samples with the addition of all three ions simultaneously were prepared using the precipitation method in an aqueous medium. Chemical, structural, spectroscopic and thermophysical analyses of the synthesized samples were conducted. The obtained results indicate that Sr(2+) ions were easily incorporated into the HA crystal structure, whereas it was difficult to incorporate Mg(2+) and Mn(2+) ions into the HA lattice when these ions were individually introduced into the samples. The synthesis of HA with Mg(2+) or Mn(2+) ions is characterized by the formation of HA with a low concentration of doping elements that is outweighed by the amount of these atoms present in less biocompatible phases that formed simultaneously. However, the incorporation of Sr(2+) along with Mg(2+) and Mn(2+) ions into the samples allowed for the synthesis of HA with considerably higher concentrations of Mg(2+) and Mn(2+) in the crystal lattice. PMID:26838904

  19. Termocromismo em soluções de alcóxidos de Vanádio(IV: uma abordagem pela modelagem molecular Thermochromic behavior of vanadium(IV alkoxides in solution: a molecular modeling aproach

    Directory of Open Access Journals (Sweden)

    Alexandre C. de Freitas

    2010-01-01

    Full Text Available The thermochromic behavior exhibited by vanadium(IV alkoxides, [V2(μ-OPr i2(OPr i 6] and [V2(μ-ONep2(ONep6 ], OPr i = isopropoxide and ONep = neopentoxide, was studied by molecular modeling using DFT, TDDFT and INDO/S methods. The vibrational and electronic spectra calculated for [V2(μ-OPr i2(OPr i 6] were very similar to the experimental data registered for crystalline samples of the complex and for its solutions at low temperature ( 315 K were compatible with those calculated for the monomeric form, [V(OPr i4]. These results consistently point to a monomer/dimer equilibrium as an explanation for the solution thermochromism of {V(OPr i4}n. In spite of the structural similarity between [V2(μ-ONep2(ONep6 ] and [V2(μ-OPr i2(OPr i 6] in the solid state, the thermochromic behavior of the former could not be explained by the same model, and the possibility of tetranuclear aggregation at low temperatures was also investigated.

  20. Effect of preparation conditions on fractal structure and phase transformations in the synthesis of nanoscale M-type barium hexaferrite

    International Nuclear Information System (INIS)

    The conditions of the synthesis of carbonate-hydroxide precursors (pH of FeOOH precipitation and heat treatment regimes) were studied in terms of their effect on the fractal structure and physical-chemical properties of precursors. Phase transformations which occur during the synthesis of nanosize M-type barium hexaferrite (BHF) were studied as well. The first structural level of precursors' aggregation for mass fractals, the correlation between fractal dimension and precursors' activity during the synthesis of BHF were determined. Synthesis parameters for the precursors with the optimal fractal structure were determined. These data permit an enhancement of the filtration coefficient of the precipitates by a factor of 4-5, obtaining substantial decrease in the temperature required for synthesis of a single-phase BHF, and monodispersed plate-like nanoparticles (60 nm diameter) with the shape anisotropy and good magnetic characteristics (saturation magnetization (Ms)=68,7 emu/g and coercitivity (Hc)=5440 Oe). - Highlights: → The nanosize M-type BHF obtained by precipitation of hydroxicarbonates technique. → Optimal fractal structure of a precursor for nanosize M-type BHF has been determined. → The precursor precipitated at pH 4.3 allows getting monodisperse particles of BHF.

  1. Controllable synthesis of CuS-P(AM-co-MAA) composite microspheres with patterned surface structures.

    Science.gov (United States)

    Zhang, Ying; Liu, Huijin; Zhao, Ya; Fang, Yu

    2008-09-15

    Copper sulfide-poly(acrylamide-co-methacrylic acid) (CuS-P(AM-co-MAA)) composite microspheres with patterned surface structures have been synthesized in a controllable manner by means of the polymer microgel template method. The formation of CuS particles can be regulated by controlling the decomposition of thioacetamide (TAA) in acidic solution. Compared with the microgel template, the surface morphologies of the composite microspheres are characterized by compact and creased textures. The surface morphology of the composite microspheres has been found to be mainly influenced by the amount of copper sulfide precipitated and hence by the rate of H(2)S gas generation. This study might provide a potential route for controlling the synthesis of various metal sulfide-polymer composites with patterned surface structures. PMID:18649893

  2. Synthesis and structure design of new bio-based elastomers via Thiol-ene-Click Reactions.

    Science.gov (United States)

    Khan, Shafiullah; Wang, Zhao; Wang, Runguo; Zhang, Liqun

    2016-10-01

    The additions of 2-mercaptoethanol to (S)-(-)-limonene via click reaction is described as an adaptable and efficient way to obtain alcohol functionalized renewable monomer for the synthesis of new cross-linkable bio-based elastomers. Thiol first reacted with the limonene endocyclic double bond and then reacted with the exocyclics double bond to form the difunctional monomer. The structure of the monomer was determined by using FTIR, (1)H NMR and mass spectrometry. Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetrys (DSC) characterization exposed that this monomer could be used to synthesize elastomers with excellent and adaptable thermal properties. The molecular weight of the synthesized elastomer could reach 186kDaa via melting polycondensation route and the structure-properties relationship was deliberated. Finally, these elastomers were mixed with dicumyl peroxide (DCP) to form cross-linked elastomers with certain mechanical property, and the gel contents of the elastomers were confirmed by using Soxhlet extraction method. PMID:27287154

  3. Synthesis and double-hierarchical structure of MoS{sub 2}/C nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Shyyko, Lyudmyla; Kotsyubynsky, Volodymyr; Budzulyak, Ivan [Department of Materials Science and New Technology, Vasyl Stefanyk Precarpathian National University, Shevchenko Street 57, 76018, Ivano-Frankivsk (Ukraine); Rawski, Michal [Analytical Laboratory of the Faculty of Chemistry, Maria Curie-Sklodowska University, M. Curie-Sklodowska Square 3, 20031, Lublin (Poland); Kulyk, Yurij [Department of Physics of Metals, Ivan Franko Lviv National University, Kyrylo and Mefodiy Street 8, 79005, Lviv (Ukraine); Lisovski, Roman [G.V. Kurdyumov Institute for Metal Physics of the N.A.S. of Ukraine, 36 Acad. Vernadsky Boulevard, 03680, Kyiv (Ukraine)

    2015-10-15

    The results of MoS{sub 2}/carbon nanocomposite hydrothermal synthesis is presented. The synthesized material was studied by XRD, TEM, EDS, SAXS, and porosimetry. The multilayer nanospheres with the average size 40-70 nm were obtained. The investigations confirm the formation of particles with double-hierarchical structure where 2H-MoS{sub 2} layers alternate with carbon layers. Atomic ratio of MoS{sub 2}:C is about 1:1 (at.%) and does not depend on the heat treatment. The proposed formation mechanism of MoS{sub 2}/C double-hierarchical structure. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    Directory of Open Access Journals (Sweden)

    Isabel Bento

    2006-11-01

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

  5. Structural Synthesis of 3-DoF Spatial Fully Parallel Manipulators

    Directory of Open Access Journals (Sweden)

    Alfonso Hernandez

    2014-07-01

    Full Text Available In this paper, the architectures of three degrees of freedom (3-DoF spatial, fully parallel manipulators (PMs, whose limbs are structurally identical, are obtained systematically. To do this, the methodology followed makes use of the concepts of the displacement group theory of rigid body motion. This theory works with so-called ‘motion generators’. That is, every limb is a kinematic chain that produces a certain type of displacement in the mobile platform or end-effector. The laws of group algebra will determine the actual motion pattern of the end-effector. The structural synthesis is a combinatorial process of different kinematic chains’ topologies employed in order to get all of the 3-DoF motion pattern possibilities in the end-effector of the fully parallel manipulator.

  6. ACCESS 3. Approximation concepts code for efficient structural synthesis: User's guide

    Science.gov (United States)

    Fleury, C.; Schmit, L. A., Jr.

    1980-01-01

    A user's guide is presented for ACCESS-3, a research oriented program which combines dual methods and a collection of approximation concepts to achieve excellent efficiency in structural synthesis. The finite element method is used for structural analysis and dual algorithms of mathematical programming are applied in the design optimization procedure. This program retains all of the ACCESS-2 capabilities and the data preparation formats are fully compatible. Four distinct optimizer options were added: interior point penalty function method (NEWSUMT); second order primal projection method (PRIMAL2); second order Newton-type dual method (DUAL2); and first order gradient projection-type dual method (DUAL1). A pure discrete and mixed continuous-discrete design variable capability, and zero order approximation of the stress constraints are also included.

  7. Synthesis, crystal structures and spectroscopic properties of cobalt(II) complexes with chelating sulfonylamidophosphate ligands

    Science.gov (United States)

    Znovjyak, Kateryna O.; Seredyuk, Maksym; Kusz, Joachim; Nowak, Maria; Moroz, Olesia V.; Sliva, Tetiana Yu; Amirkhanov, Vladimir M.

    2015-11-01

    Two new cobalt(II) complexes with general formula Co(L1)2Phen (1) and Co(L2)2Phen (2), in which HL1 = dimethyl phenylsulfonylphosphoramidate and HL2 = dimethyl tosylphosphoramidate, were prepared in one-step synthesis and characterized by IR, UV-VIS spectroscopy, TGA-DTA and elemental analysis. Moreover, the single crystal structures of 1 and 2 were determined by single crystal X-ray diffractometry. Complexes consist of mononuclear units comprising two L1-(or L2-) and phenanthroline ligands bidentatly linked to metal ion. The UV-VIS spectra of complexes in the solid state show broad asymmetric band at 530 nm attributed to the d-d transition of the metal ion. Comparing of these spectra with the absorption spectra in acetone, octahedral environment of the cobalt(II) ion in solution were considered. The structural similarity of 1 and 2 leads to a similar thermal decomposition profile.

  8. Heteroaryl Chalcones: Design, Synthesis, X-ray Crystal Structures and Biological Evaluation

    Directory of Open Access Journals (Sweden)

    Hoong-Kun Fun

    2013-10-01

    Full Text Available Chalcone derivatives have attracted increasing attention due to their numerous pharmacological activities. Changes in their structures have displayed high degree of diversity that has proven to result in a broad spectrum of biological activities. The present study highlights the synthesis of some halogen substituted chalcones 3(a–i containing the 5-chlorothiophene moiety, their X-ray crystal structures and the evaluation of possible biological activities such as antibacterial, antifungal and reducing power abilities. The results indicate the tested compounds show a varied range of inhibition values against all the tested microbial strains. Compound 3c with a p-fluoro substituent on the phenyl ring exhibits elevated antimicrobial activity, whereas the compounds 3e and 3f displayed the least antimicrobial activities. The compounds 3d, 3e, 3f and 3i showed good ferric and cupric reducing abilities, and the compounds 3b and 3c showed the weakest reducing power in the series.

  9. Translational pauses during the synthesis of proteins and mRNA structure.

    Science.gov (United States)

    Zama, M

    1997-01-01

    Translational pauses are observed during a spider fibroin synthesis (1,2). The spider major ampullate (dragline) silk of the spider Nephila clavipes is composed of multiple proteins. The amino acid sequences of the partial cDNA clones for the two major dragline silk fibroin components (Spidroin 1 and 2) exhibit repetitive motifs (3,4). Our detailed inspection of the nucleotide sequences of the repetitive motifs revealed highly selective site-specific codon usage patterns within a motif, suggesting that the secondary structure of the spider fibroin mRNA is optimized by the nucleotide sequence of the fibroin gene. The results, combined with our preceding results on silk fibroin from Bombyx mori (5) suggest that translational pauses of spider silk are interpreted in terms of the mRNA secondary structure.

  10. Medicinal properties of mangiferin, structural features, derivative synthesis, pharmacokinetics and biological activities.

    Science.gov (United States)

    Benard, Outhiriaradjou; Chi, Yuling

    2015-01-01

    The identification of biologically active and potentially therapeutically useful pharmacophores from natural products has been a long-term focus in the pharmaceutical industry. The recent emergence of a worldwide obesity and Type II diabetes epidemic has increased focus upon small molecules that can modulate energy metabolism, insulin sensitivity and fat biology. Interesting preliminary work done on mangiferin (MGF), the predominant constituent of extracts of the mango plant Mangifera indica L., portends potential for this pharmacophore as a novel parent compound for treating metabolic disorders. MGF is comprised of a C-glucosylated xanthone. Owing to the xanthone chemical structure, MGF has a redox active aromatic system and has antioxidant properties. MGF exerts varied and impressive metabolic effects in animals, improving metabolic disorders. For example we have discovered that MGF is a novel activator of the mammalian pyruvate dehydrogenase complex, leading to enhancement of carbohydrate utilization in oxidative metabolism, and leading to increased insulin sensitivity in animal models of obesity and insulin resistance. In addition, recent unbiased proteomics studies revealed that MGF upregulates proteins pivotal for mitochondrial bioenergetics and downregulates proteins controlling de novo lipogenesis in liver, helping to explain protective effects of MGF in prevention of liver steatosis. Several chemical studies have achieved synthesis of MGF, suggesting possible synthetic strategies to alter its chemical structure for development of structure-activity relationship (SAR) information. Ultimately, chemical derivatization studies could lead to the eventual development of novel therapeutics based upon the parent pharmacophore structure. Here we provide comprehensive review on chemical features of MGF, synthesis of its derivatives, its pharmacokinetics and biological activities. PMID:25827900

  11. Synthesis and structural characterization of coaxial nano tubes intercalated of molybdenum disulfide with carbon

    International Nuclear Information System (INIS)

    In this work the study of some fundamental aspects in the growth of unidimensional systems of coaxial nano tubes from the mold method is approached. This method is an inclusion technique of a precursor reagent into oxide nano porous alumina film (mold), and later applying some processes of synthesis it is gotten to obtain the wished material. The synthesized structures are identified later because they take place by means of the initial formation of nano tubes of MoS2, enclosing to carbon nano tubes by the same method, with propylene flow which generates a graphitization process that 'copy' the mold through as it flows. Binary phase MoS2 + C nano tubes were synthesized by propylene pyrolysis inside MoS2 nano tubes prepared by template assisted technique. The large coaxial nano tubes constituted of graphite sheets inserted between the MoS2 layers forming the outer part, and coaxial multi wall carbon nano tubes (MWCNT) intercalated with MoS2 inside. High resolution electron microscopy (HRTEM), electron energy loss spectroscopy (EELS), high angle annular dark field (HAADF), gatan image filter (GIF), nano beam electron diffraction patterns (NBEDP), along with molecular dynamics simulation and quantum mechanical calculations were used to characterize the samples. The one-dimensional structures exhibit diverse morphologies such as long straight and twisted nano tubes with several structural irregularities. The inter-planar spacing between MoS2 layers was found to increase from 6.3 to 7.4 A due to intercalation with carbon. Simulated HREM images revealed the presence of these twisted nano structures, with mechanical stretch into intercalate carbon between MoS2 layers. Our results open up the possibility of using MoS2 nano tubes as templates for the synthesis of new one- dimensional binary phase systems. (Author)

  12. Chemical synthesis of porous web-structured CdS thin films for photosensor applications

    International Nuclear Information System (INIS)

    The photo-activity of chemically deposited cadmium sulphide (CdS) thin film has been studied. The simple chemical route nucleates the CdS films with size up to the mean free path of the electron. Growth Kinematics of crystalline hexagonal CdS phase in the thin film form was monitored using X-ray diffraction. The time limitation set for the formation of the amorphous/nano-crystalline material is 40 and 60 min. Thereafter enhancement of the crystalline orientation along the desired plane was identified. Web-like porous structured surface morphology of CdS thin film over the entire area is observed. With decrease in synthesis time, increase of band gap energy i.e., a blue spectral shift was seen. The activation energy of CdS thin film at low and high temperature region was examined. It is considered that this activation energy corresponds to the donor levels associated with shallow traps or surface states of CdS thin film. The photo-electrochemical performance of CdS thin films in polysulphide electrolyte showed diode-like characteristics. Exposure of light on the CdS electrode increases the photocurrent. This suggests the possibility of production of free carriers via excited ions and also the light harvesting mechanism due to porous web-structured morphology. These studies hint that the obtained CdS films can work as a photosensor. - Highlights: • Photoactivity of chemically synthesized cadmium sulphide (CdS) thin films was studied. • Web-like porous structured surface morphology of CdS thin film over the entire area was observed. • Blue spectral shift with lowering of the synthesis time suggests films can act as a window layer over the absorber layer. • Porous web-structured CdS thin films can be useful in light harvesting

  13. Pure magnetic hard fct FePt nanoparticles: Chemical synthesis, structural and magnetic properties correlations

    Energy Technology Data Exchange (ETDEWEB)

    Suber, L., E-mail: lorenza.suber@ism.cnr.it [ISM-CNR, Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo Scalo, RM (Italy); Marchegiani, G. [ISM-CNR, Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo Scalo, RM (Italy); Olivetti, E.S.; Celegato, F.; Coïsson, M.; Tiberto, P. [INRIM, Electromagnetism Division, Strada delle Cacce 91, 10135 Torino (Italy); Allia, P. [DISAT Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Barrera, G. [Dipartimento di Chimica, Università di Torino, Via Pietro Giuria 7, 10125 Torino (Italy); Pilloni, L. [UTTMAT-CHI, Via Anguillarese 10, 00123 S. Maria di Galeria, Roma (Italy); Barba, L. [IC-CNR, Area Science Park, SS 14 Km 163.5 Basovizza, 34149 Trieste (Italy); Padella, F. [UTTMAT-CHI, Via Anguillarese 10, 00123 S. Maria di Galeria, Roma (Italy); Cossari, P. [IGAG-CNR, Area della Ricerca di Roma 1, Via Salaria km 29.300, 00015 Monterotondo Scalo, RM (Italy); Chiolerio, A. [Istituto Italiano di Tecnologia, Center for Space Human Robotics, Corso Trento 21, 10129 Torino (Italy)

    2014-03-01

    FePt nanoparticles, containing a near-equal atomic percentage of Fe and Pt, with a face centered tetragonal structure (fct), are challenging for potential applications in high performance permanent magnets and high density data storage. In this study, we report on the chemical synthesis, carried out both solvothermally and hydrothermally in autoclave reacting iron (III) acetylacetonate and platinum (II) acetylacetonate with tri- or tetra-ethylene glycol, these employed as solvents, reducers and particle surface protecting agents as well. In both methods, a subsequent thermal treatment at high temperatures is necessary to transform the magnetic soft face centered cubic (fcc) phase to the hard fct one. Organic low-weight molecules, generally used to protect the nanoparticle surface and avoid particle aggregation, are decomposed by the thermal treatment resulting in particle aggregation and coalescence phenomena; on the contrary, in this case, a polymer matrix is formed as particle protecting agent and, by thermally treating the hydrothermally prepared nanoparticles up to 750 °C for 1 h, the pure magnetic hard fct phase is obtained while preserving the nanostructure. A detailed study is carried out on FePt nanoparticle structure (fcc and fct phases) and correlated to the magnetic properties of the system. - Highlights: • fct FePt nanoparticles for hard magnetic nanotechnology applications. • Influence of synthesis parameters on the precursor fcc FePt nanoparticle structure. • Easy hydrothermal method for preparing pure fct FePt nanoparticles. • Monitoring the role of temperature and time on the FePt fcc–fct phase transformation. • Correlation between FePt nanoparticle structural and magnetic properties.

  14. Mechanistic Studies of Combustion and Structure Formation During Synthesis of Advanced Materials

    Science.gov (United States)

    Varma, A.; Lau, C.; Mukasyan, A. S.

    2001-01-01

    Combustion in a variety of heterogeneous systems, leading to the synthesis of advanced materials, is characterized by high temperatures (2000-3500 K) and heating rates (up to 10(exp 6) K/s) at and ahead of the reaction front. These high temperatures generate liquids and gases which are subject to gravity-driven flow. The removal of such gravitational effects is likely to provide increased control of the reaction front, with a consequent improvement in control of the microstructure of the synthesized products. Thus, microgravity (mu-g) experiments lead to major advances in the understanding of fundamental aspects of combustion and structure formation under the extreme conditions of the combustion synthesis (CS) wave. In addition, the specific features of microgravity environment allow one to produce unique materials, which cannot be obtained under terrestrial conditions. The current research is a logic continuation of our previous work on investigations of the fundamental phenomena of combustion and structure formation that occur at the high temperatures achieved in a CS wave. Our research is being conducted in three main directions: 1) Microstructural Transformations during Combustion Synthesis of Metal-Ceramic Composites. The studies are devoted to the investigation of particle growth during CS of intermetallic-ceramic composites, synthesized from nickel, aluminum, titanium, and boron metal reactants. To determine the mechanisms of particle growth, the investigation varies the relative amount of components in the initial mixture to yield combustion wave products with different ratios of solid and liquid phases, under 1g and mu-g conditions; 2) Mechanisms of Heat Transfer during Reactions in Heterogeneous Media. Specifically, new phenomena of gasless combustion wave propagation in heterogeneous media with porosity higher than that achievable in normal gravity conditions, are being studied. Two types of mixtures are investigated: clad powders, where contact between

  15. sp(2)-sp(3) diboranes: astounding structural variability and mild sources of nucleophilic boron for organic synthesis.

    Science.gov (United States)

    Dewhurst, Rian D; Neeve, Emily C; Braunschweig, Holger; Marder, Todd B

    2015-06-14

    Despite the widespread use of organoborane reagents in organic synthesis and catalysis, a major challenge still remains: very few boron-centered nucleophiles exist for the direct construction of B-C bonds. Perhaps the most promising emerging solution to this problem is the use of sp(2)-sp(3) diboranes, in which one boron atom of a conventional diborane(4) is quaternised by either a neutral or anionic nucleophile. These compounds, either isolated or generated in situ, serve as relatively mild and convenient sources of the boryl anion [BR2](-) for use in organic synthesis and have already proven their efficacy in metal-free as well as metal-catalysed borylation reactions. This Feature article documents the history of sp(2)-sp(3) diborane synthesis, their properties and surprising structural variability, and their burgeoning utility in organic synthesis.

  16. Synthesis, crystal structure of diferrous complex and its reactivity with dioxygen

    Institute of Scientific and Technical Information of China (English)

    阎世平; 程鹏; 王庆伦; 廖代正; 姜宗慧; 王耕霖

    2000-01-01

    The dinuclear complex of [Fe2L{O2P(OPh)2}](CIO4)2 ·Et2O(1) (where L represents the dinucleating ligand N-Et-HPTB, anion of N, N, N’, N’-tetrakis (N-ethyl-2-benzimidazolyemethyl)-2-hydroxy-1, 3-diamino-propane) has been synthesized and crystallizes in the triclinic space group P T with cell constants α = 1.526(3) nm, b = 1.259 8(3) nm, c = 1.563 0(3) nm , α = 94.41 (3)°, P = 115.31(3)°, β=99.90(3)°, V= 3.267(1) nm3, z=2, R = 0.084 7 and Rw = 0.177 8. The Fe(Ⅱ) sites are bridged by an alkoxide of the dinucleating ligand and a phosphate, affording a diiron core with an Fe-μ-O-Fe angle of 131.20(3)° and an Fe-Fe distance of 0.364 9 nm. Both Fe(II) centers have trigonal bipyramidal geometry. Dioxygen adduct (1/O2) forms upon exposure of the diferrous complex to O2 at low temperature (-60℃). The 1/O2 adduct is stable at -60℃ but decomposes upon warming. The adduct exhibits visible absorption maximum near 606 nm and resonance Raman features at 478 cm-1 (γFe-o) and 897 cm-1 (γo-o), and the latter

  17. Investigating the Synthesis, Structure, and Catalytic Properties of Versatile Gold-Based Nanocatalvsts

    Science.gov (United States)

    Pretzer, Lori A.

    Transition metal nanomaterials are used to catalyze many chemical reactions, including those key to environmental, medicinal, and petrochemical fields. Improving their catalytic properties and lifetime would have significant economic and environmental rewards. Potentially expedient options to make such advancements are to alter the shape, size, or composition of transition metal nanocatalysts. This work investigates the relationships between structure and catalytic properties of synthesized Au, Pd-on-Au, and Au-enzyme model transition metal nanocatalysts. Au and Pd-on-Au nanomaterials were studied due to their wide-spread application and structure-dependent electronic and geometric properties. The goal of this thesis is to contribute design procedures and synthesis methods that enable the preparation of more efficient transition metal nanocatalysts. The influence of the size and composition of Pd-on-Au nanoparticles (NPs) was systematically investigated and each was found to affect the catalyst's surface structure and catalytic properties. The catalytic hydrodechlorination of trichloroethene and reduction of 4-nitrophenol by Pd-on-Au nanoparticles were investigated as these reactions are useful for environmental and pharmaceutical synthesis applications, respectively. Structural characterization revealed that the dispersion and oxidation state of surface Pd atoms are controlled by the Au particle size and concentration of Pd. These structural changes are correlated with observed Pd-on-Au NP activities for both probe reactions, providing new insight into the structure-activity relationships of bimetallic nanocatalysts. Using the structure-dependent electronic properties of Au NPs, a new type of light-triggered biocatalyst was prepared and used to remotely control a model biochemical reaction. This biocatalyst consists of a model thermophilic glucokinase enzyme covalently attached to the surface of Au nanorods. The rod-like shape of the Au nanoparticles made the

  18. Synthesis, structure, and spectroscopic characterization of three uranyl phosphates with unique structural units

    International Nuclear Information System (INIS)

    Single crystals of Zn4(OH)2[(UO2)(PO4)2(OH)2(H2O)] (UZnP), Cs[(UO2)(HPO4)NO3] (UCsP), and In3[(UO2)2(PO4)4OH(H2O)6].2H2O (UInP) were obtained from hydrothermal reactions and have been structurally and chemically characterized. UZnP crystallizes in space group Pbcn, a=8.8817(7), b=6.6109(5), c=19.569(1) Å; UCsP crystallizes in P−1, a=7.015(2), b=7.441(1), c=9.393(2) Å, α=72.974(2), β=74.261(2), γ=79.498(2); and UInP crystallizes in P−1, a=7.9856(5), b=9.159(1), c=9.2398(6) Å α=101.289(1), β=114.642(1), γ=99.203(2). The U6+ cations are present as (UO2)2+ uranyl ions coordinated by five O atoms to give pentagonal bipyramids. The structural unit in UZnP is a finite cluster containing a uranyl pentagonal bipyramid that shares corners with two phosphate tetrahedra. The structural unit in UCsP is composed of uranyl pentagonal bipyramids with one chelating nitrate group that are linked into chains by three bridging hydrogen phosphate tetrahedra. In UInP, the structural unit contains pairs of edge-sharing uranyl pentagonal bipyramids with two chelating phosphate tetrahedra that are linked into chains through two bridging phosphate tetrahedra. Indium octahedra link these uranyl phosphate chains into a 3-dimensional framework. All three compounds exhibit unique structural units that deviate from the typical layered structures observed in uranyl phosphate solid-state chemistry. - Graphical abstract: Three new uranyl phosphates with unique structural units are reported. ▪ Highlights: ► Three new uranyl phosphates have been synthesized hydrothermally. ► Single crystal analyses reveal unique structural units. ► The dimensionality of these compounds deviate from typical U6+ layered structures

  19. Preparation and Basic Properties of BaTiO3-BaPbO3 Multilayer Thin Films by Metal-Alkoxides Method

    Science.gov (United States)

    Azuma, Takahiro; Takahashi, Sheiji; Kuwabara, Makoto

    1993-09-01

    Preferentially oriented barium titanate (BTO)-barium metaplumbate (BPO) multilayer thin films were prepared by the metal-alkoxides method on MgO single crystals. The BPO layer is an electrode for the BTO layer. Thin films were deposited on cleaved MgO (100) substrates by spin coating. A BTO film of 0.4 μm thickness on the BPO layer shows a dielectric constant of about 400 at room temperature. No formation of reaction phases between BTO and BPO, fired at 800°C to yield a well-crystallized BTO film, was detected in X-ray diffraction analysis.

  20. Influence of synthesis conditions and mesoporous structures on the gold nanoparticles supported on mesoporous silica hosts

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byunghwan [Korea Institute of Industrial Technology, ChonAn, Korea; Ma, Zhen [ORNL; Zhang, Zongtao [ORNL; Park, Chulhwan [Kwangwoon University; Dai, Sheng [ORNL

    2009-01-01

    Loading gold on mesoporous materials via different methods has been actively attempted in the literature, but the knowledge about the influences of synthesis details and different mesoporous structures on the size and thermal stability of gold nanoparticles supported on mesoporous hosts is still limited. In this study, Au/HMS, Au/MCM-41, Au/MCM-48, Au/SBA-15, and Au/SBA-16 samples were prepared by modifying a variety of mesoporous silicas by amine ligands followed by loading HAuCl4 and calcination. The influences of different amine ligands ((3-aminopropyl)triethoxysilane versus N-[3-(trimethoxysilyl)propyl]ethylenediamine), solvents (water versus ethanol), calcination temperatures (200 or 550 C), and mesoporous structures on the size of supported gold nanoparticles were systematically investigated employing nitrogen adsorption-desorption measurement, X-ray diffraction (XRD), diffuse reflectance UV-vis spectroscopy, and transmission electron microscopy (TEM). Interestingly, while big and irregular gold particles situate on MCM-48 with bicontinuous three-dimensional pore structure and relatively small pore size (2.4 nm) upon calcination at 550 C, homogeneous and small gold nanoparticles maintain inside SBA-15 with one-dimensional pore structure and relatively big pore size (6.8 nm). Apparently, the pore structure and pore size of mesoporous silica hosts play a key role in determining the size and thermal stability of the supported gold nanoparticles. Our results may provide some useful clues for the rational design of supported metal catalysts by choosing suitable mesoporous hosts.

  1. Crystal Engineering: Synthesis and Structural Analysis of Coordination Polymers with Wavelike Properties

    Directory of Open Access Journals (Sweden)

    Matasebia T. Munie

    2011-10-01

    Full Text Available Supramolecular coordination polymers with wavelike structures have been synthesized by self-assembly and their structures analyzed using the sine trigonometric function. Slow evaporation of a methylene chloride-methanol solution of a 1:1 molar mixture of [M(tmhd2], where M = Co or Ni, and quinoxaline; a 1:2:1 molar mixture of [M(acac2], where M = Co or Ni, 2,2,6,6-tetramethyl-3,5-heptadione and quinoxaline; or a 1:2:1 molar mixture of [Co(acac2], dibenzoylmethane, and quinoxaline, yielded the crystalline coordination polymers. In the presence of the nitrogenous base, ligand scrambling occurs yielding the most insoluble product. The synthesis and structures of the following wavelike polymers are reported: trans-[Co(DBM2(qox]n·nH2O (2, trans-[Co(tmhd2(qox]n (3, trans-[Ni(tmhd2(qox]n (4, where DBM− = dibenzoylmethanate, tmhd− = 2,2,6,6-tetramethyl-3,5-heptadionate, and qox = quinoxaline. The wavelike structures are generated by intramolecular steric interactions and crystal packing forces between the chains. Some of the tert-butyl groups show a two-fold disorder. The sine function, φ = A sin 2πx/λ, where φ = distance (Ǻ along the polymer backbone, λ = wavelength (Ǻ, A = amplitude (Ǻ, x = distance (Ǻ along the polymer axis, provides a method to approximate and visualize the polymer structures.

  2. Synthesis

    Directory of Open Access Journals (Sweden)

    Ivonne Alonso-Lemus

    2010-01-01

    Full Text Available MCM-41 have been used to custom synthesize catalysts in because of the controllable properties, such as pore size, active phase incorporation, crystal size, and morphology, among others. In this paper, a simple and versatile method for the incorporation of platinum, ruthenium, and palladium onto Al-MCM-41 mesoporous silica by direct inclusion of various precursors was studied. M/Al-MCM-41 structure, textural properties, morphology, and elemental composition were analyzed. The results obtained indicate that the Al-MCM-41 mesoporous-ordered structure was not affected by metallic particle incorporation. High-surface areas were obtained (1131 m2/g. Metallic nanoparticles dispersion on Al-MCM-41 was homogeneous for all samples and its particles sizes were between 6 nm to 20 nm. Microscopy results show round shape particles in platinum and palladium samples; however, ruthenium catalysts exhibit a spherical and rod shapes. Electrochemical testing for Pt/Al-MCM-41 showed electrocatalytic activity for H2 oxidation which indicates that these materials can be used as a catalyst in electrochemical devices.

  3. Synthesis and the Structural Transformation of fcc to hcp in Ni-Graphene Nanocomposite by Simple Chemical Route via Sonication

    OpenAIRE

    N. K. Mahale; R. D. Ladhe; Attarde, S. B.; S. T. Ingle

    2014-01-01

    We report the synthesis and structural transformation of fcc to hcp in Ni-graphene (Ni-Gr) composite by simple chemical route via sonication. The syntheses of Ni-Gr composite by simultaneous reduction method, and the effect of different composition ratio on morphology and crystal structure were examined in our present study. The results indicated that the graphene ratio played an important role in crystal structure and d-spacing in nickel crystals. Different compositions have shown different ...

  4. Synthesis and structural characterization of hexacoordinate silicon, germanium, and titanium complexes of the E. coli siderophore enterobactin.

    Science.gov (United States)

    Baramov, Todor; Keijzer, Karlijn; Irran, Elisabeth; Mösker, Eva; Baik, Mu-Hyun; Süssmuth, Roderich

    2013-08-01

    The E. coli siderophore enterobactin, one of the strongest Fe(III) chelators known to date, is also capable of binding Si(IV) under physiological conditions. We report on the synthesis and structural characterization of the tris(catecholate) Si(IV) -enterobactin complex and its Ge(IV) and Ti(IV) analogues. Comparative structural analysis, supported by quantum-chemical calculations, reveals the correlation between the ionic radius and the structural changes in enterobactin upon complexation.

  5. Antimicrobial profile of some novel keto esters: Synthesis, crystal structures and structure-activity relationship studies.

    Science.gov (United States)

    Khan, Imtiaz; Saeed, Aamer; Arshad, Mohammad Ifzan; White, Jonathan Michael

    2016-01-01

    Rapid increase in bacterial resistance has become a major public concern by escalating alongside a lack of development of new anti-infective drugs. Novel remedies in the battle against multidrug-resistant bacterial strains are urgently needed. So, in this context, the present work is towards the investigation of antimicrobial efficacy of some novel keto ester derivatives, which are prepared by the condensation of substituted benzoic acids with various substituted phenacyl bromides in dimethylformamide at room temperature using triethylamine as a catalyst. The structural build-up of the target compounds was accomplished by spectroscopic techniques including FTIR, (1)H and (13)C NMR spectroscopy and mass spectrometry. The purity of the synthesized compounds was ascertained by elemental analysis. The molecular structures of compounds (4b) and (4l) were established by X-ray crystallographic analysis. The prepared analogues were evaluated for their antimicrobial activity against Gram-positive (Staphylococcus aureus, Micrococcus leuteus) and Gram-negative (Pseudomonas picketti, Salmonella setuball) bacteria and two fungal pathogenic strains (Aspergillus niger, Aspergillus flavus), respectively. Among the screened derivatives, several compounds were found to possess significant activity but (4b) and (4l) turned out to be lead molecules with remarkable antimicrobial efficacy. The structure-activity relationship analysis of this study also revealed that structural modifications on the basic skeleton affected the antimicrobial activity of the synthesized compounds. PMID:26826838

  6. Synthesis and structural characterization of raffinosyl-oligofructosides upon transfructosylation by Lactobacillus gasseri DSM 20604 inulosucrase.

    Science.gov (United States)

    Díez-Municio, Marina; Herrero, Miguel; de Las Rivas, Blanca; Muñoz, Rosario; Jimeno, M Luisa; Moreno, F Javier

    2016-07-01

    A new process based on enzymatic synthesis of a series of raffinose-derived oligosaccharides or raffinosyl-oligofructosides (RFOS) with degree of polymerization (DP) from 4 to 8 was developed in the presence of raffinose. This process involves a transfructosylation reaction catalyzed by an inulosucrase from Lactobacillus gasseri DSM 20604 (IS). The main synthesized RFOS were structurally characterized by nuclear magnetic resonance (NMR). According to the elucidated structures, RFOS consist of β-2,1-linked fructose unit(s) to raffinose: α-D-galactopyranosyl-(1 → 6)-α-D-glucopyranosyl-(1↔2)-β-D-fructofuranosyl-((1 ← 2)-β-D-fructofuranoside)n (where n refers to the number of transferred fructose moieties). The maximum yield of RFOS was 33.4 % (in weight respect to the initial amount of raffinose) and was obtained at the time interval of 8-24 h of transfructosylation reaction initiated with 50 % (w/v) of raffinose. Results revealed the high acceptor and donor affinity of IS towards raffinose, being fairly comparable with that of sucrose for the production of fructooligosaccharides (FOS), including when both carbohydrates coexisted (sucrose/raffinose mixture, 250 g L(-1) each). The production of RFOS was also attempted in the presence of sucrose/melibiose mixtures; in this case, the predominant acceptor-product formed was raffinose followed by a minor production of a series of oligosaccharides with varying DP. The easiness of RFOS synthesis and the structural similarities with both raffinose and fructan series of oligosaccharides warrant the further study of the potential bioactive properties of these unexplored oligosaccharides. PMID:26940051

  7. Non-oxo vanadium(IV) alkoxide chemistry: solid state structures, aggregation equilibria and thermochromic behaviour in solution.

    Science.gov (United States)

    Westrup, Kátia C M; Gregório, Thaiane; Stinghen, Danilo; Reis, Dayane M; Hitchcock, Peter B; Ribeiro, Ronny R; Barison, Andersson; Back, Davi F; de Sá, Eduardo L; Nunes, Giovana G; Soares, Jaísa F

    2011-04-01

    The reversible thermochromic behaviour of homoleptic [{V(OR)(4)}(n)] complexes in solution [R = Pr(i) (product I), Bu(s) (B(s)), Nep (N) and Cy (C)] is accounted for the existence of an aggregation equilibrium involving dimeric and monomeric species in which vanadium(iv) is respectively five- and four-coordinate. Bulky R groups such as Bu(t) and Pe(t) (tert-pentoxide) prevent aggregation and therefore give rise to exclusively mononuclear compounds (B(t) and P(t), respectively) that are not thermochromic. The complexes and their temperature-dependent interconversion were characterised by single crystal X-ray diffractometry, magnetic susceptibility measurements and electronic, FTIR and EPR spectroscopies in a wide temperature range. Equilibrium constants and enthalpy and entropy changes for the dimerization reactions have been determined and compared with literature data. PMID:21347465

  8. Structural Synthesis of a Class of 2R2T Hybrid Mechanisms

    Institute of Scientific and Technical Information of China (English)

    TIAN Chunxu; FANG Yuefa; GUO Sheng

    2016-01-01

    Conventional overconstrained parallel manipulators have been widely studied both in industry and academia, however the structural synthesis of hybrid mechanisms with additional constraints is seldom studied, especially for the four degrees of freedom(DOF) hybrid mechanisms. In order to develop a manipulator with additional constraints, a class of important spatial mechanisms with coupling chains(CCs) whose motion type is two rotations and two translations(2R2T) is presented. Based on screw theory, the combination of different types of limbs which are used to construct parallel mechanisms and coupling chains is proposed. The basic types of the general parallel mechanisms and geometric conditions of the kinematic chains are given using constraint synthesis method. Moreover, the 2R2T motion pattern hybrid mechanisms which are derived by adding coupling chains between different serial kinematic chains(SKCs) of the corresponding parallel mechanisms are presented. According to the constraint analysis of the mechanisms, the movement relationship of the moving platform and the kinematic chains is derived by disassembling the coupling chains. At last, fourteen novel hybrid mechanisms with two or three serial kinematic chains are presented. The proposed novel hybrid mechanisms and construction method enrich the family of the spatial mechanisms and provide an instruction to design more complex hybrid mechanisms.

  9. Synthesis, molecular structure, and properties of a neutral Schiff base phenolic complex of magnesium

    Energy Technology Data Exchange (ETDEWEB)

    Polyakov, V.R.; Sharma, V.; Crankshaw, C.L.; Piwnica-Worms, D. [Washington University Medical School, St. Louis, MO (United States)

    1998-09-07

    Multidrug resistance (MDR) in cancer mediated by the MDR1 P-glycoprotein (Pgp), a 140--180 kDa plasma membrane protein, renders chemotherapeutic treatment ineffective by pumping a variety of natural product cytotoxic agents and xenobiotic compounds out of cancer cells. Pgp has been a major target for synthesis and development of both therapeutic antagonists that block its transport function and diagnostic radiopharmaceuticals that are transported by the protein for use in functional imaging of Pgp transport activity in tumors in vivo. Most, but not all, compounds that interact with Pgp are hydrophobic and cationic at physiological pH. To further understand the Pgp targeting properties, the authors sought to directly evaluate the effect of charge of the complex on Pgp interactions. This could be done by comparing the cytotoxicity profile of a neutral complex to that of an identical, but positively charged, complex in both drug-sensitive and multidrug-resistant cancer cells. Thus, a neutral analogue of the Ga(III) and Fe(III) complexes was desired. Herein the authors describe the synthesis and structure of a novel neutral Schiff base Mg complex and evaluate its cytotoxic potency in human drug-sensitive KB-3-1 and multi-drug-resistant KB-8-5 tumor cells.

  10. Structural synthesis of a class of 2R2T hybrid mechanisms

    Science.gov (United States)

    Tian, Chunxu; Fang, Yuefa; Guo, Sheng

    2016-01-01

    Conventional overconstrained parallel manipulators have been widely studied both in industry and academia, however the structural synthesis of hybrid mechanisms with additional constraints is seldom studied, especially for the four degrees of freedom(DOF) hybrid mechanisms. In order to develop a manipulator with additional constraints, a class of important spatial mechanisms with coupling chains(CCs) whose motion type is two rotations and two translations(2R2T) is presented. Based on screw theory, the combination of different types of limbs which are used to construct parallel mechanisms and coupling chains is proposed. The basic types of the general parallel mechanisms and geometric conditions of the kinematic chains are given using constraint synthesis method. Moreover, the 2R2T motion pattern hybrid mechanisms which are derived by adding coupling chains between different serial kinematic chains(SKCs) of the corresponding parallel mechanisms are presented. According to the constraint analysis of the mechanisms, the movement relationship of the moving platform and the kinematic chains is derived by disassembling the coupling chains. At last, fourteen novel hybrid mechanisms with two or three serial kinematic chains are presented. The proposed novel hybrid mechanisms and construction method enrich the family of the spatial mechanisms and provide an instruction to design more complex hybrid mechanisms.

  11. Topotactic synthesis of strontium cobalt oxyhydride thin film with perovskite structure

    Energy Technology Data Exchange (ETDEWEB)

    Katayama, Tsukasa [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan); Chikamatsu, Akira, E-mail: chikamatsu@chem.s.u-tokyo.ac.jp; Kamisaka, Hideyuki [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan); CREST, Japan Science and Technology Agency (JST), Tokyo 113-0033 (Japan); Yokoyama, Yuichi; Hirata, Yasuyuki; Wadati, Hiroki [Institute for Solid State Physics, The University of Tokyo, Chiba 277-8581 (Japan); Fukumura, Tomoteru [CREST, Japan Science and Technology Agency (JST), Tokyo 113-0033 (Japan); Department of Chemistry, Tohoku University, Miyagi 980-8578 (Japan); Hasegawa, Tetsuya [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan); CREST, Japan Science and Technology Agency (JST), Tokyo 113-0033 (Japan); Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan)

    2015-10-15

    The substitution of hydride anions (H{sup −}) into transition metal oxides has recently become possible through topotactic reactions or high-pressure synthesis methods. However, the fabrication of oxyhydrides is still difficult because of their inherently less-stable frameworks. In this study, we successfully fabricated perovskite SrCoO{sub x}H{sub y} thin films via the topotactic hydride doping of brownmillerite SrCoO{sub 2.5} epitaxial thin films with CaH{sub 2}. The perovskite-type cation framework was maintained during the topotactic treatment owing to epitaxial stabilization. Structural and chemical analyses accompanied by X-ray absorption spectroscopy measurements revealed that the doped hydride ions form a two-dimensional network of Co-H{sup −}-Co bonds, in contrast to other reported perovskite oxyhydrides, SrMO{sub 3−x}H{sub x} (M = Cr, Ti, V). The SrCoO{sub x}H{sub y} thin film exhibited insulating behavior and had a direct band gap of 2.1 eV. Thus, topotactic hydride doping of transition-metal-oxide thin films on suitable substrates is a promising method for the synthesis of new transition metal oxyhydrides.

  12. Topotactic synthesis of strontium cobalt oxyhydride thin film with perovskite structure

    Directory of Open Access Journals (Sweden)

    Tsukasa Katayama

    2015-10-01

    Full Text Available The substitution of hydride anions (H− into transition metal oxides has recently become possible through topotactic reactions or high-pressure synthesis methods. However, the fabrication of oxyhydrides is still difficult because of their inherently less-stable frameworks. In this study, we successfully fabricated perovskite SrCoOxHy thin films via the topotactic hydride doping of brownmillerite SrCoO2.5 epitaxial thin films with CaH2. The perovskite-type cation framework was maintained during the topotactic treatment owing to epitaxial stabilization. Structural and chemical analyses accompanied by X-ray absorption spectroscopy measurements revealed that the doped hydride ions form a two-dimensional network of Co-H−-Co bonds, in contrast to other reported perovskite oxyhydrides, SrMO3−xHx (M = Cr, Ti, V. The SrCoOxHy thin film exhibited insulating behavior and had a direct band gap of 2.1 eV. Thus, topotactic hydride doping of transition-metal-oxide thin films on suitable substrates is a promising method for the synthesis of new transition metal oxyhydrides.

  13. Recognizing magnetic structures by present and future radio telescopes with RM Synthesis

    CERN Document Server

    Beck, R; Stepanov, R; Sokoloff, D

    2012-01-01

    We investigate the possibilities of wavelet-based RM Synthesis for the recognition of structures of regular and turbulent magnetic fields in extended magnetized objects, like galaxies and galaxy clusters. Wavelets allow to reformulate the RM Synthesis method in a scale-dependent way and to visualize the data as a function of Faraday depth and scale. We present observational tests to recognize regular magnetic fields without and with one or two reversals along the line of sight and imprints of turbulent magnetic fields. A region with a regular magnetic field generates a broad "disk" in Faraday space ("Faraday spectrum"), with two "horns" if the distribution of cosmic-ray electrons is broader than that of the thermal electrons. Each field reversal generates one asymmetric "horn" on top of the "disk". A region with a turbulent field can be recognized by a "Faraday forest" of many components. We argue that the ratio of maximum to minimum wavelengths is an important parameter because it determines the range of sca...

  14. Synthesis, structure, and biological applications of α-fluorinated β-amino acids and derivatives.

    Science.gov (United States)

    March, Taryn L; Johnston, Martin R; Duggan, Peter J; Gardiner, James

    2012-11-01

    This review gives a broad overview of the state of play with respect to the synthesis, conformational properties, and biological activity of α-fluorinated β-amino acids and derivatives. General methods are described for the preparation of monosubstituted α-fluoro-β-amino acids (Scheme 1). Nucleophilic methods for the introduction of fluorine predominantly involve the reaction of DAST with alcohols derived from α-amino acids, whereas electrophilic sources of fluorine such as NFSI have been used in conjunction with Arndt-Eistert homologation, conjugate addition or organocatalyzed Mannich reactions. α,α-Difluoro-β-amino acids have also been prepared using DAST; however, this area of synthesis is largely dominated by the use of difluorinated Reformatsky reagents to introduce the difluoro ester functionality (Scheme 9). α-Fluoro-β-amino acids and derivatives analyzed by X-ray crystal and NMR solution techniques are found to adopt preferred conformations which are thought to result from stereoelectronic effects associated with F located close to amines, amides, and esters (Figs. 2-6). α-Fluoro amide and β-fluoro ethylamide/amine effects can influence the secondary structure of α-fluoro-β-amino acid-containing derivatives including peptides and peptidomimetics (Figs. 7-9). α-Fluoro-β-amino acids are also components of a diverse range of bioactive anticancer (e.g., 5-fluorouracil), antifungal, and antiinsomnia agents as well as protease inhibitors where such fluorinated analogs have shown increased potency and spectrum of activity.

  15. Design, synthesis, and characterization of novel nanowire structures for photovoltaics and intracellular probes.

    Science.gov (United States)

    Tian, Bozhi; Lieber, Charles M

    2011-01-01

    Semiconductor nanowires (NWs) represent a unique system for exploring phenomena at the nanoscale and are expected to play a critical role in future electronic, optoelectronic, and miniaturized biomedical devices. Modulation of the composition and geometry of nanostructures during growth could encode information or function, and realize novel applications beyond the conventional lithographical limits. This review focuses on the fundamental science aspects of the bottom-up paradigm, which are synthesis and physical property characterization of semiconductor NWs and NW heterostructures, as well as proof-of-concept device concept demonstrations, including solar energy conversion and intracellular probes. A new NW materials synthesis is discussed and, in particular, a new "nanotectonic" approach is introduced that provides iterative control over the NW nucleation and growth for constructing 2D kinked NW superstructures. The use of radial and axial p-type/intrinsic/n-type (p-i-n) silicon NW (Si-NW) building blocks for solar cells and nanoscale power source applications is then discussed. The critical benefits of such structures and recent results are described and critically analyzed, together with some of the diverse challenges and opportunities in the near future. Finally, results are presented on several new directions, which have recently been exploited in interfacing biological systems with NW devices.

  16. New bismuth borophosphate Bi4BPO10: Synthesis, crystal structure, optical and band structure analysis

    International Nuclear Information System (INIS)

    New bismuth borophosphate Bi4BPO10 was obtained by spontaneous crystallization from the melt of correspondent composition at 804 °C. Crystal structure with orthorhombic lattice parameters: a = 22.5731(3) Å, b = 14.0523(2) Å, c = 5.5149(1) Å, V = 1749.34(4), Z = 8, SG Pcab was determined by X-ray powder diffraction technique. The [Bi2O2]2+ -layers, which are typical for bismuth oxide compounds, transform into cationic endless strips of 4 bismuth atoms width directed along the c-axis in Bi4BPO10. The strips combining stacks are separated by flat triangle [BO3]3− -anions within stacks. Neighboring stacks are separated by tetrahedral [PO4]3−-anions and shifted relatively to each other. Bismuth atoms are placed in 5–7 vertex oxygen irregular polyhedra. Bi4BPO10 is stable up to 812 °C, then melts according to the peritectic law. The absorption spectrum in the range 350–700 nm was obtained and the width of the forbidden band was estimated as 3.46 eV. The band electronic structure of Bi4BPO10 was modeled using DFT approach. The calculated band gap (3.56 eV) is in good agreement with the experimentally obtained data. - Graphical abstract: Display Omitted - Highlights: • New bismuth borophosphate with composition Bi4BPO10 was synthesized. • The crystal structure was determined by X-ray powder diffraction technique. • Bismuth-oxygen part [Bi4O3]6+ forms endless strips of 4 bismuth atoms width. • Electronic structure was modeled by DFT method. • The calculated band gap (3.56 eV) is very close to the experimental one (3.46 eV)

  17. A structural-stochastic model for the analysis and synthesis of cloud images

    Science.gov (United States)

    Garand, L.; Weinman, J. A.

    1986-01-01

    A structural-stochastic image model is developed for the analysis and synthesis of cloud images. The ability of the model to characterize the visual appearance of cloud fields observed by satellite with a limited number of parameters is demonstrated. The model merges structural and stochastic information, the stochastic model acting as a local statistical operator applied to the output of the structural model. The structural or large-scale organization of the scene is retrieved from the two-dimensional Fourier representation of the digital image. The pattern generated by the major Fourier components provides a first guess of the scene. The stochastic aspect is described by a Markov model of texture that assumes a binomial probability distribution for the local grey-level variability. This Markov model provides four parameters that represent the clustering strength in the horizontal, vertical and diagonal directions. These parameters are estimated by a standard maximum-likelihood technique. The image can be reproduced with a fair degree of verisimilitude from these parameters. The data compression factor is of the order of one hundred to several hundreds.

  18. Structural Studies of Silver Nanoparticles Obtained Through Single-Step Green Synthesis

    Science.gov (United States)

    Prasad Peddi, Siva; Abdallah Sadeh, Bilal

    2015-10-01

    Green synthesis of silver Nanoparticles (AGNP's) has been the most prominent among the metallic nanoparticles for research for over a decade and half now due to both the simplicity of preparation and the applicability of biological species with extensive applications in medicine and biotechnology to reduce and trap the particles. The current article uses Eclipta Prostrata leaf extract as the biological species to cap the AGNP's through a single step process. The characterization data obtained was used for the analysis of the sample structure. The article emphasizes the disquisition of their shape and size of the lattice parameters and proposes a general scheme and a mathematical model for the analysis of their dependence. The data of the synthesized AGNP's has been used to advantage through the introduction of a structural shape factor for the crystalline nanoparticles. The properties of the structure of the AGNP's proposed and evaluated through a theoretical model was undeviating with the experimental consequences. This modus operandi gives scope for the structural studies of ultrafine particles prepared using biological methods.

  19. Synthesis, structural elucidation and carbon dioxide adsorption on Zn (II) hexacyanoferrate (II) Prussian blue analogue

    Science.gov (United States)

    Roque-Malherbe, R.; Lugo, F.; Polanco, R.

    2016-11-01

    In the course of the last years hexacyanoferrates have been widely studied; even though, the adsorption properties of Zn (II) hexacyanoferrate(II) (labelled here Zn-HII) have not been thoroughly considered. In addition, soft porous crystals, i.e., adsorbents that display structural flexibility have been, as well, extensively studied, however this property has not been reported for Zn (II) hexacyanoferrate(II). In this regard, the key questions addressed here were the synthesis and structural characterization of Zn-HII together with the investigation of their low (up to 1 bar) and high pressure (up to 30 bar) adsorption properties, to found if these materials show structural flexibility. Then, to attain the anticipated goals, structural characterizations were made with: X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) and thermo-gravimetric analysis (TGA), simultaneously, with the investigation of the adsorption of carbon dioxide. As a result of the research process we concluded that the Zn-HII displayed Fm barm space group framework. Besides, the carbon dioxide adsorption investigation demonstrated the presence of the framework expansion effect together with an extremely high adsorption heat, properties that could be useful for the use of Zn(II) hexacyanoferrate(II) as an excellent adsorbent.

  20. Synthesis of part structures of Cryptococcus neoformans serotype C capsular polysaccharide.

    Science.gov (United States)

    Guazzelli, Lorenzo; McCabe, Orla; Oscarson, Stefan

    2016-10-01

    Cryptococcus neoformans is a fungal pathogen that can cause life-threatening infections in immunocompromised patients. The development of a vaccine based on the capsular polysaccharide of C. neoformans is still an open challenge due to the heterogeneity of the capsular polysaccharide and the difficulty of identifying protective epitopes. Therefore, construction of structurally defined part structures of the C. neoformans GXM capsule is in great demand. Herein is presented the synthesis of a 3-O-naphthalenylmethyl protected trisaccharide thioglycoside building block which is present in C. neoformans serotype C polysaccharide. Its property as a donor in a glycosylation reaction with a model acceptor has been evaluated together with its behaviour as an acceptor following removal of the temporary protecting group. The heavily branched hexasaccharide was obtained in good yields and excellent α-selectivity. The frame shifted octasaccharide structural triad motif for serotype C was also prepared following the same building block strategy. For the first time this structural motif, which is the most substituted amongst the four C. neoformans serotypes, was prepared. Three synthesized C. neoformans serotype C fragments of varying size, from penta-up to octasaccharide, were deprotected and will be included in unique glycoarrays to further investigate the possibility to develop a synthetic vaccine against this pathogen. PMID:27423877

  1. Synthesis, structural characterization and quantum chemical studies of silicon-containing benzoic acid derivatives

    Science.gov (United States)

    Zaltariov, Mirela-Fernanda; Cojocaru, Corneliu; Shova, Sergiu; Sacarescu, Liviu; Cazacu, Maria

    2016-09-01

    The present paper is concerned with the synthesis and molecular structure investigation of two new benzoic acid derivatives having trimethylsilyl tails, 4-((trimethylsilyl)methoxy) and 4-(3-(trimethylsilyl)propoxy)benzoic acids. The structures of the novel compounds have been confirmed by X-ray crystallography, Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H and 13C NMR). The theoretical studies of molecules were conducted by using the quantum chemical methods, such as Density Functional Theory (DFT B3LYP/6-31 + G**), Hartree-Fock (HF/6-31 + G**) and semiempirical computations (PM3, PM6 and PM7). The optimized molecular geometries have been found to be in good agreement with experimental structures resulted from the X-ray diffraction. The maximum electronic absorption bands observed at 272-287 nm (UV-vis spectra) have been assigned to π → π* transitions, which were in reasonable agreement with the time dependent density functional theory (TD-DFT) calculations. The computed vibrational frequencies by DFT method were assigned and compared with the experimental FTIR spectra. The mapped electrostatic potentials revealed the reactive sites, which corroborated the observation of the dimer supramolecular structures formed in the crystals by hydrogen-bonding. The energies of frontier molecular orbitals (HOMO and LUMO), energy gap, dipole moment and molecular descriptors for the new compounds were calculated and discussed.

  2. Facile Synthesis of Yolk-Shell-Structured Triple-Hybridized Periodic Mesoporous Organosilica Nanoparticles for Biomedicine.

    Science.gov (United States)

    Teng, Zhaogang; Zhang, Junjie; Li, Wei; Zheng, Yuanyi; Su, Xiaodan; Tang, Yuxia; Dang, Meng; Tian, Ying; Yuwen, Lihui; Weng, Lixing; Lu, Guangming; Wang, Lianhui

    2016-07-01

    The synthesis of mesoporous nanoparticles with controllable structure and organic groups is important for their applications. In this work, yolk-shell-structured periodic mesoporous organosilica (PMO) nanoparticles simultaneously incorporated with ethane-, thioether-, and benzene-bridged moieties are successfully synthesized. The preparation of the triple-hybridized PMOs is via a cetyltrimethylammonium bromide-directed sol-gel process using mixed bridged silsesquioxanes as precursors and a following hydrothermal treatment. The yolk-shell-structured triple-hybridized PMO nanoparticles have large surface area (320 m(2) g(-1) ), ordered mesochannels (2.5 nm), large pore volume (0.59 cm(3) g(-1) ), uniform and controllable diameter (88-380 nm), core size (22-110 nm), and shell thickness (13-45 nm). In vitro cytotoxicity, hemolysis assay, and histological studies demonstrate that the yolk-shell-structured triple-hybridized PMO nanoparticles have excellent biocompatibility. Moreover, the organic groups in the triple-hybridized PMOs endow them with an ability for covalent connection of near-infrared fluorescence dyes, a high hydrophobic drug loading capacity, and a glutathione-responsive drug release property, which make them promising candidates for applications in bioimaging and drug delivery. PMID:27183872

  3. Synthesis, characterization, and structure determination of the orthorhombic U2(PO4)(P3O10)

    International Nuclear Information System (INIS)

    β-UP2O7 has been synthesized under hydrothermal conditions (θ=500 deg. C, P=200 MPa), using UO2 and H3PO4. β-UP2O7 crystallizes in the orthorhombic space group Pn21a, with a=11.526 (2) A, b=7.048 (2) A, c=12.807 (2) A and Z=4. Its structure has been determined through direct methods and difference Fourier synthesis and has been refined to R=0.0396. The structure is built on UO8 polyhedral chains along the b-axis. PO43- and P3O105- groups coexist in the structure and the latter groups form non-linear chains. Cohesion of the structure is made through the linkage of UO8 chains by PO4 and P3O10 groups leading to the formula U2(PO4)(P3O10) instead of β-UP2O7. Vibrational and optical spectra confirm the results obtained by X-ray diffraction. DTA-TGA measurements show that the transformation of U2(PO4)(P3O10) to the cubic α-UP2O7 occurs at θ=870 deg. C

  4. Characteristics of tetrahydrofuran-based electrolytes with magnesium alkoxide additives for rechargeable magnesium batteries

    Science.gov (United States)

    Kim, In-Tae; Yamabuki, Kazuhiro; Sumimoto, Michinori; Tsutsumi, Hiromori; Morita, Masayuki; Yoshimoto, Nobuko

    2016-08-01

    The electrochemical behavior of magnesium (Mg) metal was investigated in tetrahydrofuran (THF)-based solutions containing magnesium bromide (MgBr2) and/or magnesium ethoxide (Mg(OEt)2). THF solutions containing a single solute, MgBr2 or Mg(OEt)2, show no visible faradaic current based on Mg deposition and/or dissolution. However, the electrolyte system containing both solutes, MgBr2 + Mg(OEt)2/THF, gives a reversible current response of Mg deposition and dissolution. The ionic structure of the electrolyte system containing the binary solute was examined by infrared (IR) spectroscopy and density functional theory (DFT) calculations. It was confirmed that MgBr2 and Mg(OEt)2 are coordinated (solvated) with THF molecules to form an EtOsbnd Mgsbnd Br·4THF complex. The DFT calculations also suggest the possible formation of μ-complexes for the MgBr2/Mg(OEt)2 binary system in THF. The voltammetric responses at the Pt electrode indicate low overpotential and high coulombic efficiency for Mg deposition and dissolution in THF-based solutions containing suitable molar ratios of MgBr2 and Mg(OEt)2. The constant-current charge-discharge cycling of Mg in MgBr2 + Mg(OEt)2/THF electrolyte also shows low overpotential and good cyclability over 300 cycles.

  5. Nanoparticle synthesis of zinc peroxide: structural and morphological characterization for bactericidal applications

    International Nuclear Information System (INIS)

    Zinc peroxide (ZnO2) nanoparticles were synthesized by sol-gel technique. The chemicals used for the synthesis were zinc acetate di-hydrate (Zn(CH3COO)2.2H2O) and hydrogen peroxide (H2O2) at 30 % in an aqueous solution with sonication. The structure of the ZnO2 nanoparticles was characterized by X-ray diffraction. While the morphology and the cluster size were determined using scanning and transmission electron microscopy. For a preliminary evaluation of the bactericidal properties of the ZnO2, the material was exposed to Staphylococcus aureus, Escherichia coli y Bacillus subtili, and the nanoparticles presented good bactericidal properties. (author)

  6. Synthesis and structural characterization of piperazino-modified DNA that favours hybridization towards DNA over RNA

    DEFF Research Database (Denmark)

    Skov, Joan; Bryld, Torsten; Lindegaard, Dorthe;

    2011-01-01

    We report the synthesis of two C4'-modified DNA analogues and characterize their structural impact on dsDNA duplexes. The 4'-C-piperazinomethyl modification stabilizes dsDNA by up to 5°C per incorporation. Extension of the modification with a butanoyl-linked pyrene increases the dsDNA stabilization...... multiple sites in intermediate exchange on the NMR timescale, resulting in broad lines in NMR spectra. We identified two intercalation sites with NOE data showing that the pyrene prefers to intercalate one base pair away from the modified nucleotide with its linker curled up in the minor groove. Both...... modifications are tolerated in DNA:RNA hybrids but leave their melting temperatures virtually unaffected. Fluorescence data indicate that the pyrene moiety is residing outside the helix. The available data suggest that the DNA discrimination is due to (i) the positive charge of the piperazino ring having a...

  7. Mesoporous Structure Control of Silica in Room-Temperature Synthesis under Basic Conditions

    Directory of Open Access Journals (Sweden)

    Jeong Wook Seo

    2015-01-01

    Full Text Available Various types of mesoporous silica, such as continuous cubic-phase MCM-48, hexagonal-phase MCM-41, and layer-phase spherical silica particles, have been synthesized at room temperature using cetyltrimethylammonium bromide as a surfactant, ethanol as a cosurfactant, tetraethyl orthosilicate as a silica precursor, and ammonia as a condensation agent. Special care must be taken both in the filtering of the resultant solid products and in the drying process. In the drying process, further condensation of the silica after filtering was induced. As the surfactant and cosurfactant concentrations in the reaction mixture increased and the NH3 concentration decreased, under given conditions, continuous cubic MCM-48 and layered silica became the dominant phases. A cooperative synthesis mechanism, in which both the surfactant and silica were involved in the formation of mesoporous structures, provided a good explanation of the experimental results.

  8. In silico structure-based design and synthesis of novel anti-RSV compounds.

    Science.gov (United States)

    Cancellieri, Michela; Bassetto, Marcella; Widjaja, Ivy; van Kuppeveld, Frank; de Haan, Cornelis A M; Brancale, Andrea

    2015-10-01

    Respiratory syncytial virus (RSV) is the major cause for respiratory tract disease in infants and young children. Currently, no licensed vaccine or a selective antiviral drug against RSV infections are available. Here, we describe a structure-based drug design approach that led to the synthesis of a novel series of zinc-ejecting compounds active against RSV replication. 30 compounds, sharing a common dithiocarbamate moiety, were designed and prepared to target the zinc finger motif of the M2-1 protein. A library of ∼ 12,000 small fragments was docked to explore the area surrounding the zinc ion. Among these, seven ligands were selected and used for the preparation of the new derivatives. The results reported here may help the development of a lead compound for the treatment of RSV infections. PMID:26259810

  9. Synthesis, characterisation and crystal structures of two bi-oxadiazole derivatives featuring the trifluoromethyl group.

    Science.gov (United States)

    Kettner, Marcos A; Klapötke, Thomas M; Witkowski, Tomasz G; von Hundling, Felix

    2015-03-01

    The synthesis, characterisation, and crystal structure determination of the closely related compounds 3,3'-bi-(5-trifluoromethyl-1,2,4-oxadiazole) and 5,5'-bi-(2-trifluoromethyl-1,3,4-oxadiazole) are reported. These two compounds are known for their bioactivity; however, in this study they serve as model compounds to evaluate the suitability of the heterocyclic oxadiazole ring system for energetic materials when the fluorine atoms in the exocyclic CF3 groups are substituted successively by nitro groups. Quantum chemical calculations for the bi-1,3,4-oxadiazole derivatives with difluoronitromethyl, fluorodinitromethyl, and trinitromethyl groups have been carried out and predict promising energetic performances for both explosive and propulsive applications.

  10. Synthesis, X-ray crystal structure and theoretical calculations of antileishmanial neolignan analogues

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Josenaide P. do; Santos, Lourivaldo S.; Carmo, Maria Carolina L. do; Brasil, Davi S.B.; Alves, Claudio N., E-mail: nahum@ufpa.b [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Inst. de Ciencias Exatas e Naturais; Santos, Regina Helena A.; Tozzo, Erica; Ferreira, Janaina G. [Universidade de Sao Paulo (IQSC/USP), Sao Carlos, SP (Brazil). Inst. de Quimica

    2010-07-01

    The synthesis and X-ray crystal diffraction structure of two analogues of neolignans, 2-(4-chlorophenyl)-1-phenylethanone (20) and 2-[(4-chlorophenyl)thio]-1-(3,4-dimethoxyphenyl) propan-1-one (12) is described. The compound 12 presents activity against intracellular Leishmania donovani and Leishmania amazonensis amastigotes that cause cutaneous and visceral leishmaniasis. In addition, the density functional theory (DFT) with the B3LYP hybrid functional was employed to calculate a set of molecular descriptors for nineteen synthetic analogues of neolignans with antileishmanial activities. Afterwards, the stepwise discriminant analysis was performed to investigate possible relationship between the molecular descriptors and biological activities. Through this analysis the compounds were classified into two groups active and inactive according to their degree of biological activities, and the more important properties were charges on some key atoms, electronic affinity and ClogP. (author)

  11. Functionalized O6-Corona[6]arenes: Synthesis, Structure, and Fullerene Complexation Property.

    Science.gov (United States)

    Ren, Wen-Sheng; Zhao, Liang; Wang, Mei-Xiang

    2016-07-01

    The synthesis, structure, and fullerene complexation property of novel and functionalized On-corona[n]arenes were reported. Based on the fragment coupling strategy, ester-containing On-corona[n]arenes (n = 6, 8) were obtained readily starting from 1,4-hydroquinone and diethyl 2,5-difluoroterephthalate. Reduction of esters with LiAlH4 produced almost quantitatively hydroxymethylated On-corona[n]arenes, which underwent etherification with MeI to afford methoxymethyl-substituted On-corona[n]arenes (n = 6, 8) in good yields. The macrocycles adopt unique corona-type conformation with a large cylindroid cavity. They are strong macrocyclic host molecules to form 1:1 complexes with fullerenes C60 and C70 in toluene with an associate constant up to (1.59 ± 0.04) × 10(5) M(-1). PMID:27324274

  12. Functionalized O6-Corona[6]arenes: Synthesis, Structure, and Fullerene Complexation Property.

    Science.gov (United States)

    Ren, Wen-Sheng; Zhao, Liang; Wang, Mei-Xiang

    2016-07-01

    The synthesis, structure, and fullerene complexation property of novel and functionalized On-corona[n]arenes were reported. Based on the fragment coupling strategy, ester-containing On-corona[n]arenes (n = 6, 8) were obtained readily starting from 1,4-hydroquinone and diethyl 2,5-difluoroterephthalate. Reduction of esters with LiAlH4 produced almost quantitatively hydroxymethylated On-corona[n]arenes, which underwent etherification with MeI to afford methoxymethyl-substituted On-corona[n]arenes (n = 6, 8) in good yields. The macrocycles adopt unique corona-type conformation with a large cylindroid cavity. They are strong macrocyclic host molecules to form 1:1 complexes with fullerenes C60 and C70 in toluene with an associate constant up to (1.59 ± 0.04) × 10(5) M(-1).

  13. Synthesis and structural characterization of three unique Helicobacter pylori α-cholesteryl phosphatidyl glucosides.

    Science.gov (United States)

    Nguyen, Huy Q; Davis, Ryan A; Gervay-Hague, Jacquelyn

    2014-12-01

    Steryl glycosides produced by bacteria play important biological roles in the evasion and modulation of host immunity. Step-economical syntheses of three cholesteryl-6-O-phosphatidyl-α-D-glucopyranosides (αCPG) unique to Helicobacter pylori have been achieved. The approach relies upon regioselective deprotection of per-O-trimethylsilyl-α-D-cholesterylglucoside at C6 followed by phosphoramidite coupling. Global TMS ether deprotection in the presence of oxygen and subsequent deprotection of the cyano ethyl phosphoester afforded the target compounds in 16-21 % overall yield starting from D-glucose. The structures of these natural products were determined using a combination of 2D NMR methods and mass spectrometry. These robust synthesis and characterization protocols provide analogues to facilitate glycolipidomic profiling and biological studies. PMID:25195783

  14. Synthesis, growth, structure determination and optical properties of chalcone derivative single crystal

    Science.gov (United States)

    Karthi, S.; Girija, E. K.

    2014-04-01

    Acquiring large nonlinear optical (NLO) efficient organic material is essential for the development of optoelectronics and photonic devices. Chalcone is the donor - Π - acceptor - Π - donor (D-Π-A-Π-D) type conjugated molecule with appreciable hyperpolarizability of potential interest in NLO applications. The addition of vinyl and electron donor groups in the chalcone molecule may enhance the second harmonic generation (SHG) efficiency. Here we report the synthesis, crystal growth and characterization of a chalcone derivative 1-(4-methylphenyl)-5-(4-methoxyphenyl)-penta-2,4-dien-1-one (MPMPP). The MPMPP crystal was grown by slow evaporation solution growth technique from acetone. The grown crystal structure was studied by single crystal X-ray diffraction. The SHG efficiency of the grown crystal was determined by Kurtz and Perry method.

  15. Synthesis, growth, structure determination and optical properties of chalcone derivative single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Karthi, S., E-mail: girijaeaswaradas@gmail.com; Girija, E. K., E-mail: girijaeaswaradas@gmail.com [Department of Physics, Periyar University, Salem - 636011 (India)

    2014-04-24

    Acquiring large nonlinear optical (NLO) efficient organic material is essential for the development of optoelectronics and photonic devices. Chalcone is the donor - Π - acceptor - Π - donor (D-Π-A-Π-D) type conjugated molecule with appreciable hyperpolarizability of potential interest in NLO applications. The addition of vinyl and electron donor groups in the chalcone molecule may enhance the second harmonic generation (SHG) efficiency. Here we report the synthesis, crystal growth and characterization of a chalcone derivative 1-(4-methylphenyl)-5-(4-methoxyphenyl)-penta-2,4-dien-1-one (MPMPP). The MPMPP crystal was grown by slow evaporation solution growth technique from acetone. The grown crystal structure was studied by single crystal X-ray diffraction. The SHG efficiency of the grown crystal was determined by Kurtz and Perry method.

  16. Fused 1,2,3-Dithiazoles: Convenient Synthesis, Structural Characterization, and Electrochemical Properties

    Directory of Open Access Journals (Sweden)

    Lidia S. Konstantinova

    2016-05-01

    Full Text Available A new general protocol for synthesis of fused 1,2,3-dithiazoles by the reaction of cyclic oximes with S2Cl2 and pyridine in acetonitrile has been developed. The target 1,2,3-dithiazoles fused with various carbocycles, such as indene, naphthalenone, cyclohexadienone, cyclopentadiene, and benzoannulene, were selectively obtained in low to high yields. In most cases, the hetero ring-closure was accompanied by chlorination of the carbocyclic moieties. With naphthalenone derivatives, a novel dithiazole rearrangement (15→13 featuring unexpected movement of the dithiazole ring from α- to β-position, with respect to keto group, was discovered. Molecular structure of 4-chloro-5H-naphtho[1,2-d][1,2,3]dithiazol-5-one 13 was confirmed by single-crystal X-ray diffraction. Electrochemical properties of 13 were studied by cyclic voltammetry and a complex behavior was observed, most likely including hydrodechlorination at a low potential.

  17. [Synthesis of acyclic 1,3-polyols and its application to structural study of natural products].

    Science.gov (United States)

    Mori, Y

    1993-06-01

    A 1,3-polyhydroxylated chain is often found on the backbone of biologically important natural products. The acyclic nature and the regular array of many hydroxyl groups are main obstacles to structural and synthetic studies, and many efforts have been made to this end. We have developed a new general synthetic method of 1,3-polyols based on the coupling of a chiral dithiane, a four-carbon unit, and an epoxide, followed by 1,3-diastereoselective reduction. We applied the method to the synthesis of polymethoxy-1-alkenes isolated from blue-green algae to establish their absolute stereochemistry. Moreover, a general procedure for assigning the absolute stereochemistry of acyclic 1,3-polyols by the difference circular dichroism (CD) method have been established. Combination of the method and a reiterative degradation enables one to determine the absolute configuration of 1,3-polyols, even if the relative stereochemistry is unknown. PMID:8355146

  18. Trends in computerized structural analysis and synthesis; Proceedings of the Symposium, Washington, D.C., October 30-November 1, 1978

    Science.gov (United States)

    Noor, A. K. (Editor); Mccomb, H. G., Jr.

    1978-01-01

    The subjects considered are related to future directions of structural applications and potential of new computing systems, advances and trends in data management and engineering software development, advances in applied mathematics and symbolic computing, computer-aided instruction and interactive computer graphics, nonlinear analysis, dynamic analysis and transient response, structural synthesis, structural analysis and design systems, advanced structural applications, supercomputers, numerical analysis, and trends in software systems. Attention is given to the reliability and optimality of the finite element method, computerized symbolic manipulation in structural mechanics, a standard computer graphics subroutine package, and a drag method as a finite element mesh generation scheme.

  19. Synthesis and crystal structure of 5-(4'-carboxyphenyl)-10,15,20-tri(4¢-t-butylphenyl)porphinato zinc(II) complex

    Indian Academy of Sciences (India)

    P Bhyrappa; C Arunkumar; J J Vittal

    2005-03-01

    Synthesis and crystal structure of 5-(4'-carboxyphenyl)-10,15,20-tri(4'--butylphenyl)porphinato zinc(II) have been presented. The title complex shows interesting hydrogen-bonded dimeric structure in the solid state.

  20. Structural considerations on acridine/acridinium derivatives: Synthesis, crystal structure, Hirshfeld surface analysis and computational studies

    Science.gov (United States)

    Wera, Michał; Storoniak, Piotr; Serdiuk, Illia E.; Zadykowicz, Beata

    2016-02-01

    This article describes a detailed study of the molecular packing and intermolecular interactions in crystals of four derivatives of acridine, i.e. 9-methyl-, 9-ethyl, 9-bromomethyl- and 9-piperidineacridine (1, 2, 3 and 4, respectively) and three 10-methylacridinium salts containing the trifluoromethanesulphonate anion and 9-vinyl-, 9-bromomethyl, and 9-phenyl-10-methylacridinium cations (5, 6 and 7, respectively). The crystal structures of all of the compounds are stabilized by long-range electrostatic interactions, as well as by a network of short-range C-HṡṡṡO (in hydrates and salts 3 and 5-7, respectively), C-Hṡṡṡπ, π-π, C-Fṡṡṡπ and S-Oṡṡṡπ (in salts 5-7) interactions. Hirshfeld surface analysis shows that various intermolecular contacts play an important role in the crystal packing, graphically exhibiting the differences in spatial arrangements of the acridine/acridinium derivatives under scrutiny here. Additionally, computational methods have been used to compare the intermolecular interactions in the crystal structures of the investigated compounds. Computations have confirmed the great contribution of dispersive interactions for crystal lattice stability in the case of 9-substituted acridine and electrostatic interactions for the crystal lattice stability in the case of 9-substituted 10-methylacridinium trifluoromethanesulphonates. The value of crystal lattice energy and the electrostatic contribution in the crystal lattice energy of monohydrated acridine derivatives have confirmed that these compounds have behave as acridinium derivatives.

  1. Synthesis and structural characterization of nano-hydroxyapatite biomaterials prepared by microwave processing

    Science.gov (United States)

    Ramli, Rosmamuhamadani; Arawi, Ainaa Zafirah Omar; Talari, Mahesh Kumar; Mahat, Mohd Muzamir; Jais, Umi Sarah

    2012-07-01

    Synthetic hydroxyapatite, (HA, Ca10(PO4)6(OH)2), is an attractive and widely utilized bio-ceramic material for orthopedic and dental implants because of its close resemblance of native tooth and bone crystal structure. Synthetic HA exhibits excellent osteoconductive properties. Osteoconductivity means the ability to provide the appropriate scaffold or template for bone formation. Calcium phosphate biomaterials [(HA), tri-calcium phosphate (TCP) and biphasic calcium phosphate (HA/TCP)] with appropriate three-dimensional geometry are able to bind and concentrate endogenous bone morphogenetic proteins in circulation, and may become osteoinductive and can be effective carriers of bone cell seeds. This HA can be used in bio-implants as well as drug delivery application due to the unique properties of HA. Biomaterials synthesized from the natural species like mussel shells have additional benefits such as high purity, less expensive and high bio compatibility. In this project, HA-nanoparticles of different crystallite size were prepared by microwave synthesis of precursors. High purity CaO was extracted from the natural mussel shells for the synthesis of nano HA. Dried nano HA powders were analyzed using X-Ray Diffraction (XRD) technique for the determination of crystal structure and impurity content. Scanning Electron Microscopic (SEM) investigation was employed for the morphological investigation of nano HA powders. From the results obtained, it was concluded that by altering the irradiation time, nano HA powders of different crystallite sizes and morphologies could be produced. Crystallite sizes calculated from the XRD patterns are found to be in the range of 10-55 nm depending on the irradiation time.

  2. Synthesis of 2-monoacylglycerols and structured triacylglycerols rich in polyunsaturated fatty acids by enzyme catalyzed reactions.

    Science.gov (United States)

    Rodríguez, Alicia; Esteban, Luis; Martín, Lorena; Jiménez, María José; Hita, Estrella; Castillo, Beatriz; González, Pedro A; Robles, Alfonso

    2012-08-10

    This paper studies the synthesis of structured triacylglycerols (STAGs) by a four-step process: (i) obtaining 2-monoacylglycerols (2-MAGs) by alcoholysis of cod liver oil with several alcohols, catalyzed by lipases Novozym 435, from Candida antartica and DF, from Rhizopus oryzae, (ii) purification of 2-MAGs, (iii) formation of STAGs by esterification of 2-MAGs with caprylic acid catalyzed by lipase DF, from R. oryzae, and (iv) purification of these STAGs. For the alcoholysis of cod liver oil, absolute ethanol, ethanol 96% (v/v) and 1-butanol were compared; the conditions with ethanol 96% were then optimized and 2-MAG yields of around 54-57% were attained using Novozym 435. In these 2-MAGs, DHA accounted for 24-31% of total fatty acids. In the operational conditions this lipase maintained a stable level of activity over at least 11 uses. These results were compared with those obtained with lipase DF, which deactivated after only three uses. The alcoholysis of cod liver oil and ethanol 96% catalyzed by Novozym 435 was scaled up by multiplying the reactant amounts 100-fold and maintaining the intensity of treatment constant (IOT=3g lipase h/g oil). In these conditions, the 2-MAG yield attained was about 67%; these 2-MAGs contained 36.6% DHA. The synthesized 2-MAGs were separated and purified from the alcoholysis reaction products by solvent extraction using solvents of low toxicity (ethanol and hexane); 2-MAG recovery yield and purity of the target product were approximately 96.4% and 83.9%, respectively. These 2-MAGs were transformed to STAGs using the optimal conditions obtained in a previous work. After synthesis and purification, 93% pure STAGs were obtained, containing 38% DHA at sn-2 position and 60% caprylic acid (CA) at sn-1,3 positions (of total fatty acids at these positions), i.e. the major TAG is the STAG with the structure CA-DHA-CA.

  3. To Evaluate the Application of Alkoxide Sol-Gel Method in Fabrication of 3YSZ-MWCNTs Nanocomposites, in an Attempt to Improve Its Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Ali Ahmadi

    2014-01-01

    Full Text Available In the present research work, fabrication of YSZ-CNTs composite system through alkoxide sol-gel processing was evaluated, in an attempt to improve its mechanical properties. Nanocomposites containing 0.5–2 wt% MWCNTs were then fabricated through the hydrolysis and condensation processing of the solution mixtures containing alkoxide and inorganic precursors along with the functionalized CNTs under basic condition and its final sintering by the SPS technique at 1400°C. Results showed the formation of a nanocomposite powder based on pure 3YSZ matrix, with well dispersion of CNTs and its good adhesion to the matrix particles in composite containing 0.5 wt% CNTs. The fracture toughness of sintered samples showed around 24% increase for the composite containing 0.5 wt% CNTs. The fracture toughness, hardness, and density decreased due to the agglomeration of CNTs over 0.5 wt%. Toughening mechanisms including pullout and crack bridging were observed on the polished and fractured surfaces.

  4. Total synthesis and structural confirmation of the marine natural product Dysinosin A: a novel inhibitor of thrombin and Factor VIIa.

    Science.gov (United States)

    Hanessian, Stephen; Margarita, Roberto; Hall, Adrian; Johnstone, Shawn; Tremblay, Martin; Parlanti, Luca

    2002-11-13

    The structure and absolute configuration of the marine antithrombotic product dysinosin A was confirmed by total synthesis. The strategy involved disconnections to three subunits, of which two were synthesized from the readily available l-glutamic acid, d-leucine, and d-mannitol. The Grubbs olefin metathesis carbocyclization reaction was utilized to prepare two intermediates. PMID:12418860

  5. Synthesis, Biological Evaluation and Structure-Activity Relationships of New Quinoxaline Derivatives as Anti-Plasmodium falciparum Agents

    Directory of Open Access Journals (Sweden)

    Ana Gil

    2014-02-01

    Full Text Available We report the synthesis and antimalarial activities of eighteen quinoxaline and quinoxaline 1,4-di-N-oxide derivatives, eight of which are completely novel. Compounds 1a and 2a were the most active against Plasmodium falciparum strains. Structure-activity relationships demonstrated the importance of an enone moiety linked to the quinoxaline ring.

  6. Synthesis, biological evaluation and structure-activity relationships of new quinoxaline derivatives as anti-Plasmodium falciparum agents.

    Science.gov (United States)

    Gil, Ana; Pabón, Adriana; Galiano, Silvia; Burguete, Asunción; Pérez-Silanes, Silvia; Deharo, Eric; Monge, Antonio; Aldana, Ignacio

    2014-02-18

    We report the synthesis and antimalarial activities of eighteen quinoxaline and quinoxaline 1,4-di-N-oxide derivatives, eight of which are completely novel. Compounds 1a and 2a were the most active against Plasmodium falciparum strains. Structure-activity relationships demonstrated the importance of an enone moiety linked to the quinoxaline ring.

  7. Immobilized Cu (II)—Amino Acid Complexes as Prospective Highly Efficient Catalytic Materials: Synthesis, Structural Characterization and Catalytic Activities

    Science.gov (United States)

    Pálinkó, István; Ordasi, Adrien; Kiss, János T.; Labádi, Imre

    2008-11-01

    In this work the covalent anchoring of N-or C-protected Cu(II)—L-tyrosine complexes onto a swellable resin or surface-modified silica gel is described. Experimental conditions (solvents, the availability of ligands) of the synthesis were varied; the structures (by IR spectroscopy) and the superoxide dismutase activities of the anchored complexes were studied.

  8. [New biological active derivatives of indomethacin and acetylsalicylic acid. Synthesis, physico-chemical characterisation and structure validation].

    Science.gov (United States)

    Stan, Catalina; Stefanache, Alina; Dumitrache, M

    2006-01-01

    It is well known that niflumic acid glycinamide has a good antiinflammatory action useful in gum inflammatory diseases. The objective of this study was to obtain new glycinamides of acetylsalicylic acid and indomethacin, which could have a better antiinflammatory action than niflumic acid glycinamide. The study presents the synthesis, physico-chemical characterisation and structure validation of these glycinamides.

  9. Synthesis, Biological Evaluation and Structure-Activity Relationships of New Quinoxaline Derivatives as Anti-Plasmodium falciparum Agents

    OpenAIRE

    Ana Gil; Adriana Pabón; Silvia Galiano; Asunción Burguete; Silvia Pérez-Silanes; Eric Deharo; Antonio Monge; Ignacio Aldana

    2014-01-01

    We report the synthesis and antimalarial activities of eighteen quinoxaline and quinoxaline 1,4-di-N-oxide derivatives, eight of which are completely novel. Compounds 1a and 2a were the most active against Plasmodium falciparum strains. Structure-activity relationships demonstrated the importance of an enone moiety linked to the quinoxaline ring.

  10. Synthesis of silver nanoparticles by sophorolipids: Effect of temperature and sophorolipid structure on the size of particles

    Indian Academy of Sciences (India)

    M B Kasture; P Patel; A A Prabhune; C V Ramana; A A Kulkarni; B L V Prasad

    2008-11-01

    We report in situ synthesis of silver nanoparticles using biosurfactants called sophorolipids as reducing and capping agents. We further study the effect of temperature and the structure of sophorolipid on the size of silver nanoparticles obtained. The silver nanoparticles were characterized by UVvisible, transmission electron microscope (TEM) and light scattering (DLS) analysis techniques.

  11. Dispersed metal cluster catalysts by design. Synthesis, characterization, structure, and performance

    Energy Technology Data Exchange (ETDEWEB)

    Arslan, Ilke [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Dixon, David A. [Univ. of Alabama, Tuscaloosa, AL (United States); Gates, Bruce C. [Univ. of California, Davis, CA (United States); Katz, Alexander [Univ. of California, Berkeley, CA (United States)

    2015-09-30

    To understand the class of metal cluster catalysts better and to lay a foundation for the prediction of properties leading to improved catalysts, we have synthesized metal catalysts with well-defined structures and varied the cluster structures and compositions systematically—including the ligands bonded to the metals. These ligands include supports and bulky organics that are being tuned to control both the electron transfer to or from the metal and the accessibility of reactants to influence catalytic properties. We have developed novel syntheses to prepare these well-defined catalysts with atomic-scale control the environment by choice and placement of ligands and applied state-of-the art spectroscopic, microscopic, and computational methods to determine their structures, reactivities, and catalytic properties. The ligands range from nearly flat MgO surfaces to enveloping zeolites to bulky calixarenes to provide controlled coverages of the metal clusters, while also enforcing unprecedented degrees of coordinative unsaturation at the metal site—thereby facilitating bonding and catalysis events at exposed metal atoms. With this wide range of ligand properties and our arsenal of characterization tools, we worked to achieve a deep, fundamental understanding of how to synthesize robust supported and ligand-modified metal clusters with controlled catalytic properties, thereby bridging the gap between active site structure and function in unsupported and supported metal catalysts. We used methods of organometallic and inorganic chemistry combined with surface chemistry for the precise synthesis of metal clusters and nanoparticles, characterizing them at various stages of preparation and under various conditions (including catalytic reaction conditions) and determining their structures and reactivities and how their catalytic properties depend on their compositions and structures. Key characterization methods included IR, NMR, and EXAFS spectroscopies to identify

  12. Synthesis by irradiation and mechanism and structural characterization study of high melt strength polypropylene

    International Nuclear Information System (INIS)

    Polypropylene molecular structure is made only by linear molecules interacting by weak forces. The resulting PP has very low melt strength (MS). MS is important to make feasible to process PP by all the transformation technologies based on the free expansion of the melt. The aim of this work was to develop a new process to synthesize PP with crosslinks and/or long chain branches, known as High Melt Strength Polypropylene (HMSPP) and to characterize its structure and synthesis mechanism. HMSPP was obtained by the irradiation of PP under a crosslinking (acetylene) atmosphere or inert or oxidative one, followed by thermal treatment for radical recombination and thermal treatment for annihilation of the remaining radicals under reactive or inert atmosphere. The results from rheological characterization showed that the highest levels of MS were obtained by conducting irradiation and thermal treatments under crosslinking atmospheres. The results for the elucidation of reaction mechanism by electron spin resonance (ESR) showed that acetylene irradiation is effective in promoting the creation of double bonds, based on the formation of polyenil radicals. The results of structural unraveling showed that radiation promotes predominantly the degradation of atactic molecules or molecules with atactic defects. These results support the hypothesis of formation of branched PP molecules based on the reaction of those fragments with the double bonds created in the PP molecules. (author)

  13. Synthesis, structural and optical properties of nanoparticles (Al, V) co-doped zinc oxide

    Indian Academy of Sciences (India)

    J El Ghoul

    2016-02-01

    The synthesis by the sol–gel method, structural and optical properties of ZnO, Zn0.99Al0.01O (AlZ), Zn0.9V0.1O (VZ) and Zn0.89Al0.01V0.1O (AlVZ) nanoparticles was reported. The approach was slow release of water for hydrolysis by esterification reaction followed by a supercritical drying in ethyl alcohol. After thermal treatment at 500°C in air, the obtained nanopowders were characterized by various techniques such as transmission electron microscopy, X-ray diffraction and photoluminescence (PL) spectroscopy. The structural properties showed that the ZnO nanoparticles with an average particle size of 25 nm exhibit hexagonal wurtzite structure. From the optical studies, it was found that the optical band gap was located between 2.97 and 3.17 eV. The obtained electrical properties showed the potential application of the samples in optoelectronic devices. The powder of AlVZ presented a strong luminescence band in the visible range. The PL band energy position presented a small blue shift with the increase of measurement temperature. Different possible attributions of this emission band will be discussed.

  14. Synthesis and structure of new microporous Nd(III) silicates of the rhodesite group

    Energy Technology Data Exchange (ETDEWEB)

    Munha, Rui F.; Ananias, Duarte; Almeida Paz, Filipe A.; Rocha, Joao [Aveiro Univ. (Portugal). CICECO - Aveiro Institute of Materials

    2015-07-01

    The synthesis and structural characterization of two novel trivalent neodymium microporous silicates whose structures are reminiscent of the structure of mineral montregianite of the rhodesite group, and their infrared light-emission properties are reported. The compound KNa{sub 2}Nd[Si{sub 8}O{sub 19}] . 5H{sub 2}O (1) crystallizes in the orthorhombic Pmma space group: a = 23.9016(17) Aa, b = 6.9980(5) Aa, c = 6.5474(5) Aa. Heating 1 at 200 C for 40 min affords a new partially dehydrated phase, KNa{sub 2}Nd[Si{sub 8}O{sub 19}] . 2.8H{sub 2}O (2), also crystallizing in the orthorhombic Pmma space group: a = 23.923(4) Aa, b = 6.9950(11) Aa, c = 6.5474(10) Aa. Compound 2 is the hydrated phase with the lowest content of water molecule reported to date in the rhodesite mineral series.

  15. Synthesis and structure of high-quality films of copper polyphthalocyanine – 2D conductive polymer

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • 2D polymers show a big promise for science and technology. • We develop a new procedure for the direct synthesis of copper polyphthalocyanine. • We obtain reliable experimental data on the CuPPC structure. • With the support of quantum chemical calculations we describe electronic structure of CuPPC. - Abstract: Copper polyphthalocyanine (CuPPC), a 2D conjugated polymer, is a promising material for electronics and photovoltaics, but its applications were hindered by a poor processability. We propose an experimental approach, by which thin films of CuPPC, can be directly synthesized in a chemical vapor deposition (CVD) set-up at mild temperature (420 °C). High polymerization degree and high crystallinity of the films were confirmed by TEM, FTIR and UV–vis studies. From XRD and TEM electron diffraction, we conclude that the polymer has AA layer stacking with the inter-layer distance of 0.32 nm. The assignment of X-ray and TEM diffraction patterns was based on quantum-chemical calculations. Based on the latter, we also discuss electronic structure and conclude that CuPPC is rather a semi-metal than semi-conductor

  16. Radio Frequency Plasma Synthesis of Boron Nitride Nanotubes (BNNTs) for Structural Applications: Part I

    Science.gov (United States)

    Hales, Stephen J.; Alexa, Joel A.; Jensen, Brian J.; Thomsen, Donald L.

    2016-01-01

    It is evident that nanotubes, such as carbon, boron nitride and even silicon, offer great potential for many aerospace applications. The opportunity exists to harness the extremely high strength and stiffness exhibited by high-purity, low-defect nanotubes in structural materials. Even though the technology associated with carbon nanotube (CNT) development is mature, the mechanical property benefits have yet to be fully realized. Boron nitride nanotubes (BNNTs) offer similar structural benefits, but exhibit superior chemical and thermal stability. A broader range of potential structural applications results, particularly as reinforcing agents for metal- and ceramic- based composites. However, synthesis of BNNTs is more challenging than CNTs mainly because of the higher processing temperatures required, and mass production techniques have yet to emerge. A promising technique is radio frequency plasma spray (RFPS), which is an inductively coupled, very high temperature process. The lack of electrodes and the self- contained, inert gas environment lend themselves to an ultraclean product. It is the aim of this White Paper to survey the state of the art with regard to nano-material production by analyzing the pros and cons of existing methods. The intention is to combine the best concepts and apply the NASA Langley Research Center (LaRC) RFPS facility to reliably synthesize large quantities of consistent, high-purity BNNTs.

  17. Synthesis, structure, and fullerene-complexing property of azacalix[6]aromatics.

    Science.gov (United States)

    Fa, Shi-Xin; Wang, Li-Xia; Wang, De-Xian; Zhao, Liang; Wang, Mei-Xiang

    2014-04-18

    Synthesis, structure, and fullerene-binding property of azacalix[6]aromatics were systematically studied. By means of [3 + 3] and [2 + 2 + 2] fragment coupling protocols, a number of azacalix[6]aromatics containing different combinations of benzene, pyridine, and pyrimidine rings and various substituents on the bridging nitrogen atoms were synthesized conveniently in moderate to good yields. The resulting macrocycles adopt in the solid state symmetric and heavily distorted 1,3,5-alternate conformations depending on the aromatic building units, whereas, in solution, they exist as a mixture of conformers that undergo rapid interchanges relative to the NMR time scale. All macrocycles were able to form 1:1 complexes with C60 and C70 in toluene with the association constants up to 7.28 × 10(4) M(-1). In the crystalline state, azacalix[6]aromatics form complexes with C60 and C70 with 2:1, 1:1, and 1:2 stoichiometric ratios between host and guest. Azacalix[6]aromatics interact with fullerene by forming mainly the sandwich structure in which C60 or C70 is sandwiched by two macrocycles. X-ray molecular structures revealed that multiple π-π and CH-π interactions between concave azacalix[6]aromatics and convex fullerenes C60 and C70 contribute a joint driving force to the formation of host-guest complexes.

  18. Using a precursor in lamellar structure for the synthesis of uniform ZnS nanocrystals

    KAUST Repository

    Xu, Xinjiang

    2011-11-12

    Uniform ZnS nanocrystals of about 15 nm were prepared through a low temperature hydrothermal approach by treating Zn-PhPO nanosheets with Na 2S aqueous solution. Both the precursor and the final product were studied by the means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The photo-luminescent spectrum of the synthesized ZnS nanocrystals showed their good crystalline nature. Based on this study, the precursor structure-controlling effect was discussed, and in addition, the relevant factors possibly affecting the particle formation and the growth possessed were applied in the discussion to interpret the transformation mechanism. Further research showed that both the structure characters of the precursors and the mass transportation which occurred during the synthesis greatly affected the morphology and organization state of the final products. This research may provide some facts on the structure-controlling approaches along with a general method for the preparation of uniform sulfide nanocrystals. © Springer Science+Business Media B.V. 2011.

  19. Synthesis, crystal structure, electronic structure, and photoelectric response properties of KCu2SbS3.

    Science.gov (United States)

    Wang, Ruiqi; Zhang, Xian; He, Jianqiao; Zheng, Chong; Lin, Jianhua; Huang, Fuqiang

    2016-02-28

    Copper thioantimonates have received enormous attention due to their potential for applications in photovoltaic devices. In this work, a new layered compound KCu2SbS3 was synthesized via a reactive flux method using thiourea as a reactive flux. The compound crystallizes in the triclinic space group P1[combining macron]. The structure features two-dimensional [Cu2SbS3](-) layers stacking along the c axis with K(+) ions intercalated between the layers. Each [Cu2SbS3](-) layer is composed of two single graphene-like layers connected via interlayer Cu-S bonds and CuSb contacts. The optical measurements indicate that the compound has a band gap of 1.7 eV. The Hall effect measurement shows that KCu2SbS3 is a p-type semiconductor with a carrier concentration of 7 × 10(16) cm(-3). First-principles calculations reveal that the direct transition occurs between Cu-3d-S-3p orbitals (VBM) to Sb-5p-S-3p orbitals (CBM). The photoelectric response properties of KCu2SbS3 under visible light irradiation were analyzed. The photocurrent is 3.7 μA cm(-2) at 10 V bias, demonstrating its potential for applications in photoelectric devices.

  20. Component mode synthesis and large deflection vibration of complex structures. Volume 1: Examples of NASTRAN modal synthesis capability

    Science.gov (United States)

    Mei, Chuh; Shen, Mo-How

    1987-01-01

    The use of NASTRAN model synthesis capability is illustrated. A classical truss problem is examined and the results are compared to results from other methods to test for accuracy. The problem is examined using both fixed interface modes and free interface modes. The solution is carried out for an applied dynamic load as far as recovery of forces in individual members as a function of time. Another small beam problem is used to compare different means of combining substructures.

  1. Development of a Probabilistic Dynamic Synthesis Method for the Analysis of Nondeterministic Structures

    Science.gov (United States)

    Brown, A. M.

    1998-01-01

    Accounting for the statistical geometric and material variability of structures in analysis has been a topic of considerable research for the last 30 years. The determination of quantifiable measures of statistical probability of a desired response variable, such as natural frequency, maximum displacement, or stress, to replace experience-based "safety factors" has been a primary goal of these studies. There are, however, several problems associated with their satisfactory application to realistic structures, such as bladed disks in turbomachinery. These include the accurate definition of the input random variables (rv's), the large size of the finite element models frequently used to simulate these structures, which makes even a single deterministic analysis expensive, and accurate generation of the cumulative distribution function (CDF) necessary to obtain the probability of the desired response variables. The research presented here applies a methodology called probabilistic dynamic synthesis (PDS) to solve these problems. The PDS method uses dynamic characteristics of substructures measured from modal test as the input rv's, rather than "primitive" rv's such as material or geometric uncertainties. These dynamic characteristics, which are the free-free eigenvalues, eigenvectors, and residual flexibility (RF), are readily measured and for many substructures, a reasonable sample set of these measurements can be obtained. The statistics for these rv's accurately account for the entire random character of the substructure. Using the RF method of component mode synthesis, these dynamic characteristics are used to generate reduced-size sample models of the substructures, which are then coupled to form system models. These sample models are used to obtain the CDF of the response variable by either applying Monte Carlo simulation or by generating data points for use in the response surface reliability method, which can perform the probabilistic analysis with an order of

  2. Aluminum Complexes Stabilized by Piperazidine-Bridged Bis(phenolate) Ligands: Syntheses, Structures, and Applica- tion in the Ring-Opening Polymerization of ε-Caprolactone

    Institute of Scientific and Technical Information of China (English)

    李文艺; 姚英明; 张勇; 沈琪

    2012-01-01

    The synthesis and characterization of aluminum alkoxide and alkyl complexes stabilized by piperazidine- bridged bis(phenolate) ligands are described. Treatment of ligand precursors Hz[ONNO]^1 {Hz[ONNO]^1= 1,4-bis(2-hydroxy-3-tert-butyl-5-methylbenzyl)piperazidine} and Hz[ONNO]2 {H2[ONNO]2=1,4-bis(2-hydroxy3,5-di-tert-butylbenzyl)piperazidine} with A1Et2(OCH2Ph) and A1Etz(OPr-i), which were generated in situ by the reactions of AIEt3 with equivalent of the corresponding alcohols, in a 1: 1 molar ratio in THF gave the corresponding aluminum alkoxide complexes [ONNO]IAI(OCH2Ph) (1) and [ONNO]2Al(OPr-i) (2), respectively. The reaction of H2[ONNO]^1 with A1Etz(OCHzPh) in a 1 : 2 molar ratio in THF afforded a mixture of monometallic aluminum ethyl complex [ONNO] 1A1Et (3) and complex 1, which can be isolated by stepwise crystallization. Similarly, Hz[ONNO]2 reacted with A1Etz(OPr-0 in a 1: 2 molar ratio in THF to give a mixture of aluminum ethyl complex [ONNO]2AlEt (4) and complex 2. Complexes 1 and 2 were also available via treatment of complexes 3 and 4 with 1 equiv, of benzyl alcohol and isopropyl alcohol, respectively. All of these complexes were fully characterized including X-ray structural determination. It was found that complexes 1 to 4 can initiate the ring-opening polymerization of e-caprolactone, and complexes 1 and 2 showed higher catalytic activity in comparison with com- plexes 3 and 4.

  3. Poly(ADP-ribose)--a unique natural polymer structural features, biological role and approaches to the chemical synthesis.

    Science.gov (United States)

    Drenichev, Mikhail S; Mikhailov, Sergey N

    2015-01-01

    Poly(ADP-ribose) (PAR) is a natural polymer, taking part in numerous important cellular processes. Several enzymes are involved in biosynthesis and degradation of PAR. One of them, poly(ADP-ribose)polymerase-1 (PARP-1) is considered to be a perspective target for the design of new drugs, affecting PAR metabolism. The structure of PAR was established by enzymatic hydrolysis and further analysis of the products, but total chemical synthesis of PAR hasn't been described yet. Several approaches have been developed on the way to chemical synthesis of this unique biopolymer.

  4. Synthesis of Titania-Silica Materials by Sol-Gel

    Directory of Open Access Journals (Sweden)

    Rubia F. S. Lenza

    2002-10-01

    Full Text Available In this work TiO2-SiO2 glasses containing as much as 20 mol % of TiO2 were prepared via sol-gel process using titanium and silicon alkoxides, in the presence of chlorine, in the form of titanium tetrachloride or HCl. The gels were heat-treated until 800 °C. X-ray diffraction and Fourier transform infrared spectroscopy were used to understand the structural properties of TiO2-SiO2 oxides calcined at different temperatures and to evaluate the homogeneity of these materials. The degree of the compactness of the silica network is inferred from the frequency of the asymmetric stretching vibrations of Si-O-Si bonds. Formation of Si-O-Ti bridges, as monitored by the intensity of characteristic 945 cm-1 ¾ 960 cm-1 vibration, is particularly prominent if the method of basic two-step prehydrolysis of silicon alkoxide, addition of titanium alkoxide and completion of hydrolysis was used.

  5. Design, synthesis, and characterization of new phosphazene related materials, and study the structure property correlations

    Science.gov (United States)

    Tian, Zhicheng

    The work described in this thesis is divided into three major parts, and all of which involve the exploration of the chemistry of polyphosphazenes. The first part (chapters 2 and 3) of my research is synthesis and study polyphoshazenes for biomedical applications, including polymer drug conjugates and injectable hydrogels for drug or biomolecule delivery. The second part (chapters 4 and 5) focuses on the synthesis of several organic/inorganic hybrid polymeric structures, such as diblock, star, brush and palm tree copolymers using living cationic polymerization and atom transfer radical polymerization techniques. The last part (chapters 6 and 7) is about exploratory synthesis of new polymeric structures with fluorinated side groups or cycloaliphatic side groups, and the study of new structure property relationships. Chapter 1 is an outline of the fundamental concepts for polymeric materials, as such the history, important definitions, and some introductory material for to polymer chemistry and physics. The chemistry and applications of phopshazenes is also briefly described. Chapter 2 is a description of the design, synthesis, and characterization of development of a new class of polymer drug conjugate materials based on biodegradable polyphosphazenes and antibiotics. Poly(dichlorophosphazene), synthesized by a thermal ring opening polymerization, was reacted with up to 25 mol% of ciprofloxacin or norfloxacin and three different amino acid esters (glycine, alanine, or phenylalanine) as cosubstituents via macromolecular substitutions. Nano/microfibers of several selected polymers were prepared by an electrospinning technique. Chapter 3 is concerned with the development of a class of injectable and biodegradable hydrogels based on water-soluble poly(organophosphazenes) containing oligo(ethylene glycol) methyl ethers and glycine ethyl esters. The hydrogels can be obtained by mixing alpha-cyclodextrin aqueous solution and poly(organophosphazenes) aqueous solution in

  6. Total synthesis, structural, and biological evaluation of stylissatin A and related analogs.

    Science.gov (United States)

    Shaheen, Farzana; Jabeen, Almas; Ashraf, Samreen; Nadeem-Ul-Haque, Muhammad; Shah, Zafar Ali; Ziaee, Muhammad Asad; Dastagir, Nida; Ganesan, A

    2016-09-01

    The natural product cyclic peptide stylissatin A (1a) was reported to inhibit nitric oxide production in LPS-stimulated murine macrophage RAW 264.7 cells. In the current study, solid-phase total synthesis of stylissatin A was performed by using a safety-catch linker and yielded the peptide with a trans-Phe(7) -Pro(6) linkage, whereas the natural product is the cis rotamer at this position as evidenced by a marked difference in NMR chemical shifts. In order to preclude the possibility of 1b being an epimer of the natural product, we repeated the synthesis using d-allo-Ile in place of l-Ile and a different site for macrocyclization. The resulting product (d-allo-Ile(2) )-stylissatin A (1c) was also found to have the trans-Phe(7) -Pro(6) peptide conformations like rotamer 1b. Applying the second route to the synthesis of stylissatin A itself, we obtained stylissatin A natural rotamer 1a accompanied by rotamer 1b as the major product. Rotamers 1a, 1b, and the epimer 1c were separable by HPLC, and 1a was found to match the natural product in structure and biological activity. Six related analogs 2-7 of stylissatin A were synthesized on Wang resin and characterized by spectral analysis. The natural product (1a), the rotamer (1b), and (d-allo-Ile(2) )-stylissatin A (1c) exhibited significant inhibition of NO(.) . Further investigations were focused on 1b, which also inhibited proliferation of T-cells and inflammatory cytokine IL-2 production. The analogs 2-7 weakly inhibited NO(.) production, but strongly inhibited IL-2 cytokine production compared with synthetic peptide 1b. All analogs inhibited the proliferation of T-cells, with analog 7 having the strongest effect. In the analogs, the Pro(6) residue was replaced by Glu/Ala, and the SAR indicates that the nature of this residue plays a role in the biological function of these peptides. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. PMID:27526945

  7. Synthesis and structure-activity relationships of potent antitumor active quinoline and naphthyridine derivatives.

    Science.gov (United States)

    Srivastava, Sanjay K; Jha, Amrita; Agarwal, Shiv K; Mukherjee, Rama; Burman, Anand C

    2007-11-01

    The disease of cancer has been ranked second after cardiovascular diseases and plant-derived molecules have played an important role for the treatment of cancer. Nine cytotoxic plant-derived molecules such as vinblastine, vincristine, navelbine, etoposide, teniposide, taxol, taxotere, topotecan and irinotecan have been approved as anticancer drugs. Recently, epothilones are being emerging as future potential anti-tumor agents. However, targeted cancer therapy has now been rapidly expanding and small organic molecules are being exploited for this purpose. Amongst target specific small organic molecules, quinazoline was found as one of the most successful chemical class in cancer chemotherapy as three drugs namely Gefitinib, Erlotinib and Canertinib belong to this series. Now, quinazoline related chemical classes such as quinolines and naphthyridines are being exploited in cancer chemotherapy and a number of molecules such as compounds EKB-569 (52), HKI-272 (78) and SNS-595 (127a) are in different phases of clinical trials. This review presents the synthesis of quinolines and naphthyridines derivatives, screened for anticancer activity since year 2000. The synthesis of most potent derivatives in each prototype has been delineated. A brief structure activity relationship for each prototype has also been discussed. It has been observed that aniline group at C-4, aminoacrylamide substituents at C-6, cyano group at C-3 and alkoxy groups at C-7 in the quinoline ring play an important role for optimal activity. While aminopyrrolidine functionality at C-7, 2'-thiazolyl at N-1 and carboxy group at C-3 in 1,8-naphthyridine ring are essential for eliciting the cytotoxicity. This review would help the medicinal chemist to design and synthesize molecules for targeted cancer chemotherapy. PMID:18045063

  8. Synthesis and Characterization of Ru Cubic Nanocages with a Face-Centered Cubic Structure by Templating with Pd Nanocubes.

    Science.gov (United States)

    Zhao, Ming; Figueroa-Cosme, Legna; Elnabawy, Ahmed O; Vara, Madeline; Yang, Xuan; Roling, Luke T; Chi, Miaofang; Mavrikakis, Manos; Xia, Younan

    2016-08-10

    Nanocages have received considerable attention in recent years for catalytic applications owing to their high utilization efficiency of atoms and well-defined facets. Here we report, for the first time, the synthesis of Ru cubic nanocages with ultrathin walls, in which the atoms are crystallized in a face-centered cubic (fcc) rather than hexagonal close-packed (hcp) structure. The key to the success of this synthesis is to ensure layer-by-layer deposition of Ru atoms on the surface of Pd cubic seeds by controlling the reaction temperature and the injection rate of a Ru(III) precursor. By selectively etching away the Pd from the Pd@Ru core-shell nanocubes, we obtain Ru nanocages with an average wall thickness of 1.1 nm or about six atomic layers. Most importantly, the Ru nanocages adopt an fcc crystal structure rather than the hcp structure observed in bulk Ru. The synthesis has been successfully applied to Pd cubic seeds with different edge lengths in the range of 6-18 nm, with smaller seeds being more favorable for the formation of Ru shells with a flat, smooth surface due to shorter distance for the surface diffusion of the Ru adatoms. Self-consistent density functional theory calculations indicate that these unique fcc-structured Ru nanocages might possess promising catalytic properties for ammonia synthesis compared to hcp Ru(0001), on the basis of strengthened binding of atomic N and substantially reduced activation energies for N2 dissociation, which is the rate-determining step for ammonia synthesis on hcp Ru catalysts. PMID:27458871

  9. Synthesis, crystal structure and properties of double neptunium(4) cesium sulfates

    International Nuclear Information System (INIS)

    Paper presents data on synthesis, structure and spectral properties of Cs2Np(SO4)3 · 2H2O. The absorption electron spectra (500-1050 nm) and the IR spectra (400-4000 cm-1) were measured in NaCl pellets. One managed to grow Cs2Nh(SO4)3 · 2H2O monocrystals (monoclinic syngony, a = 6.434(1), b = 9.522(1), c = 11.111(1) A, β = 92.56(1) deg, V = 680.0(2) A3, Z = 2, dcom = 4.039 g/cm3, space group-P21). The crystalline structure of Cs2Np(SO4)3 · 2H2O was lamellar one. The anion layers parallel to (001) plane consisted of Np4+ cations, of SO42- anions and of molecules of neptunium bond coordination water. Alkaline cations and water molecules included in Cs+ coordination sphere located within the interlayer space. Np4+ coordination polyhedron was formed by nine atoms of oxygen, one of which belonged to water molecule the rest ones belonged to sulfate-ions. The lengths of Np-O bonds varied from 2.328 up to 2.505 A (average one constituted 2.405 A), O-Np-O valent angles varied from 56.7 up to 95.6 deg. Within Cs2Np(SO4)3 · 2H2O structure there were three crystallographically independent sulfate-ions that were not equivalent as to the structure (one was bidentate, two were tridentate-bridging ligands)

  10. A microporous potassium vanadyl phosphate analogue of mahnertite. Hydrothermal synthesis and crystal structure

    Energy Technology Data Exchange (ETDEWEB)

    Yakubovich, Olga V. [M.V. Lomonosov Moscow State Univ. (Russian Federation). Dept. of Crystallography; Russian Academy of Science, Moscow (Russian Federation). Inst. of Geology of Deposits, Petrography, Mineralogy and Geochemistry; Steele, Ian M. [Notre Dame Univ., IN (United States). Notre Dame Integrated Imaging Facility; Kiriukhina, Galina V.; Dimitrova, Olga V. [M.V. Lomonosov Moscow State Univ. (Russian Federation). Dept. of Crystallography

    2015-09-01

    The novel phase K{sub 2.5}Cu{sub 5}Cl(PO{sub 4}){sub 4}(OH){sub 0.5}(VO{sub 2}).H{sub 2}O was prepared by hydrothermal synthesis at 553 K. Its crystal structure was determined using low-temperature (100 K) single-crystal synchrotron diffraction data and refined against F{sup 2} to R = 0.035. The compound crystallizes in the tetragonal space group I4/mmm, with unit-cell parameters a =9.8120(8), c = 19.954(1) Aa, V = 1921.1(2) Aa{sup 3}, and Z = 4. Both symmetrically independent Cu{sup 2+} sites show elongated square-pyramidal coordination. The V{sup 5+} ions reside in strongly distorted five-vertex VO{sub 5} polyhedra with 50% occupancy. The structure is based on a 3D anionic framework built from Cu- and V-centered five-vertex polyhedra and PO{sub 4} tetrahedra. Channels in the [100] and [010] directions accommodate large K atoms and H{sub 2}O molecules. The compound is a new structural representative of the topology shown by the lavendulan group of copper arsenate and phosphate minerals. Their tetragonal or pseudotetragonal crystal structures are characterized by two types of 2D slabs alternating along one axis of their unit cells. One slab, described by the formula [Cu{sub 4}X(TO{sub 4}){sub 4}]{sub 8} (where X = Cl, O and T = As, P), is common to all phases, whereas the slab content of the other set differs among the group members. We suggest interpreting this family of compounds in terms of the modular concept and also consider the synthetic phase Ba(VO)Cu{sub 4}(PO{sub 4}){sub 4} as a simplest member of this polysomatic series.

  11. Discrete polynuclear manganese(ii) complexes with thiacalixarene ligands: synthesis, structures and photophysical properties.

    Science.gov (United States)

    Suffren, Yan; O'Toole, Niall; Hauser, Andreas; Jeanneau, Erwann; Brioude, Arnaud; Desroches, Cédric

    2015-05-01

    The synthesis, crystal structure and photophysical properties of the new compound [Mn4(ThiaSO2)2F][K(18-crown-6)], ThiaSO2 = p-tert-butylsulphonylcalix[4]arene, are presented and compared to the ones of [Mn4(ThiaSO2)2F]K. The strong orange luminescence is attributed to the Mn(2+) centred (4)T1→(6)A1 transition. Its temperature and pressure dependence and quenching by molecular dioxygen are reported. The latter is attributed to energy transfer from the (4)T1 state exciting dioxygen to its (1)∑(+)g state. In the solid state, the quenching is much more efficient in [Mn4(ThiaSO2)2F][K(18-crown-6)] than in [Mn4(ThiaSO2)2F]K. This is attributed to the open pore structure of the former allowing fast diffusion of dioxygen into the crystal lattice. PMID:25825820

  12. Synthesis and structure of some nano-sized rare-earth metal ions doped potassium hexacyanoferrates

    Science.gov (United States)

    Narayan, Himanshu; Alemu, Hailemichael; Nketsa, Pusetso F.; Manatha, Toka J.; Madhavi Thakurdesai, And

    2015-05-01

    Rare-earth ions doped potassium hexacyanoferrates (KR-HCF); with the general formula KRFe(CN)6 · 3H2 O [with, R≡Y, Gd and Yb] nanoparticles were synthesized through precipitation. Characterization was done through particle-size analyzer, scanning electron microscopy (SEM), Fourier Transform infra-red (FTIR) and Raman spectroscopy, and powder X-ray diffraction (XRD). The XRD data was analyzed on FullProf Software Suite program and the unit-cell structure and lattice parameters of KR-HCF samples were determined from scratch and refined further. All the three KR-HCF nanoparticles seem to crystallize in the orthorhombic primitive PMMM space-group. Reasonably good agreement was found with the previously reported lattice constants of KGd-HCF and KYb-HCF orthorhombic single-crystals, except that they assume different space-groups. The observed dissimilarity of space-groups may be attributed to the different time scales involved in the synthesis process. Moreover, the crystal structure of KYFe(CN)6 · 3H2 O nanoparticles is being reported for the very first time.

  13. Facile synthesis of diverse graphene nanomeshes based on simultaneous regulation of pore size and surface structure

    Science.gov (United States)

    Zhang, Jia; Song, Huaibing; Zeng, Dawen; Wang, Hao; Qin, Ziyu; Xu, Keng; Pang, Aimin; Xie, Changsheng

    2016-01-01

    Recently, graphene nanomesh (GNM) has attracted great attentions due to its unique porous structure, abundant active sites, finite band gap and possesses potential applications in the fields of electronics, gas sensor/storage, catalysis, etc. Therefore, diverse GNMs with different physical and chemical properties are required urgently to meet different applications. Herein we demonstrate a facile synthetic method based on the famous Fenton reaction to prepare GNM, by using economically fabricated graphene oxide (GO) as a starting material. By precisely controlling the reaction time, simultaneous regulation of pore size from 2.9 to 11.1 nm and surface structure can be realized. Ultimately, diverse GNMs with tunable band gap and work function can be obtained. Specially, the band gap decreases from 4.5–2.3 eV for GO, which is an insulator, to 3.9–1.24 eV for GNM-5 h, which approaches to a semiconductor. The dual nature of electrophilic addition and oxidizability of HO• is responsible for this controllable synthesis. This efficient, low-cost, inherently scalable synthetic method is suitable for provide diverse and optional GNMs, and may be generalized to a universal technique. PMID:27561350

  14. Facile synthesis of diverse graphene nanomeshes based on simultaneous regulation of pore size and surface structure

    Science.gov (United States)

    Zhang, Jia; Song, Huaibing; Zeng, Dawen; Wang, Hao; Qin, Ziyu; Xu, Keng; Pang, Aimin; Xie, Changsheng

    2016-08-01

    Recently, graphene nanomesh (GNM) has attracted great attentions due to its unique porous structure, abundant active sites, finite band gap and possesses potential applications in the fields of electronics, gas sensor/storage, catalysis, etc. Therefore, diverse GNMs with different physical and chemical properties are required urgently to meet different applications. Herein we demonstrate a facile synthetic method based on the famous Fenton reaction to prepare GNM, by using economically fabricated graphene oxide (GO) as a starting material. By precisely controlling the reaction time, simultaneous regulation of pore size from 2.9 to 11.1 nm and surface structure can be realized. Ultimately, diverse GNMs with tunable band gap and work function can be obtained. Specially, the band gap decreases from 4.5–2.3 eV for GO, which is an insulator, to 3.9–1.24 eV for GNM-5 h, which approaches to a semiconductor. The dual nature of electrophilic addition and oxidizability of HO• is responsible for this controllable synthesis. This efficient, low-cost, inherently scalable synthetic method is suitable for provide diverse and optional GNMs, and may be generalized to a universal technique.

  15. Synthesis and Structural Characterization of Schiff Base Ligand and their Metal Complexes

    Directory of Open Access Journals (Sweden)

    Amit Kumar Gautam

    2016-05-01

    Full Text Available In the present work, the synthesis and structural characterization of a 2-phenyl- 3(benzamido propyl quinazoline (3H -4- one semicarbazone/ thiosemicarbazone hydrochloride and its metal complexes have been reported. All the synthesized compounds were characterized by using various physico-chemical techniques such as Infrared spectra, electronic spectra, molar conductivity and magnetic susceptibility measurements. The ligand and metal ions reacted to form in the 2:1 ratio as found from the elemental analyses and general stiochiometry was determined, [M(PBPQS2X2] and [M(PBPQT2X2]; where M = Co(II, Ni(II and Cu(II; PBPQS = 2-phenyl- 3 (benzamido propyl quinazoline (3H -4- one semicarbazone and PBPQT = 2- phenyl- 3 (benzamido propyl quinazoline (3H -4- one thiosemicarbazone. On the basis of analytical data, a proposed structure for the Cu(II complexes are distorted octahedral and those for Co(II and Ni(II complexes are octahedral. Ligands PBPQS/ PBPQT have been proposed to act in a bidentate manner co-ordinating to the metal ions though azomethine nitrogen and oxygen/ sulphur atom of either semicarbazone/ thiosemicarbazone moiety. The remaining co-ordination sites are occupied by negative ions such as Cl-, Br-, I- or NO3-. The ligands and its metal complexes were tested for their possible antimicrobial potentials.

  16. Facile synthesis of diverse graphene nanomeshes based on simultaneous regulation of pore size and surface structure.

    Science.gov (United States)

    Zhang, Jia; Song, Huaibing; Zeng, Dawen; Wang, Hao; Qin, Ziyu; Xu, Keng; Pang, Aimin; Xie, Changsheng

    2016-01-01

    Recently, graphene nanomesh (GNM) has attracted great attentions due to its unique porous structure, abundant active sites, finite band gap and possesses potential applications in the fields of electronics, gas sensor/storage, catalysis, etc. Therefore, diverse GNMs with different physical and chemical properties are required urgently to meet different applications. Herein we demonstrate a facile synthetic method based on the famous Fenton reaction to prepare GNM, by using economically fabricated graphene oxide (GO) as a starting material. By precisely controlling the reaction time, simultaneous regulation of pore size from 2.9 to 11.1 nm and surface structure can be realized. Ultimately, diverse GNMs with tunable band gap and work function can be obtained. Specially, the band gap decreases from 4.5-2.3 eV for GO, which is an insulator, to 3.9-1.24 eV for GNM-5 h, which approaches to a semiconductor. The dual nature of electrophilic addition and oxidizability of HO(•) is responsible for this controllable synthesis. This efficient, low-cost, inherently scalable synthetic method is suitable for provide diverse and optional GNMs, and may be generalized to a universal technique. PMID:27561350

  17. Strontium substituted hydroxyapatites: Synthesis and determination of their structural properties, in vitro and in vivo performance

    International Nuclear Information System (INIS)

    The objective of this study is to present a detailed report related to the synthesis and characterization of strontium substituted hydroxyapatites. Based on this purpose, hydroxyapatite (HAp) bioceramics with different amounts of strontium (e.g., 0, 0.45, 0.90, 1.35, 1.80 and 2.25 at.%) were prepared using a sol–gel method. The effects of Sr substitution on the structural properties and biocompatibility of the samples were studied by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques, in vitro and in vivo tests. All the samples composed of the nanoparticles ranging from 21 to 27 nm. The presence of Sr at low levels influenced the crystal size, crystallinity degree, lattice parameters and volume of the unit cell of the HAp. Both in vitro conditions and soaking period in simulated body fluid (SBF) significantly affected these properties. Especially, the (Ca + Sr)/P molar ratio gradually decreases with increasing soaking period in SBF. Animal experiments revealed the bone formation and osseointegration for all samples, and as compared with other groups, more reasonable, were observed for the sample with the lowest Sr content. - Highlights: • Sr content affects the structural properties of hydroxyapatite. • Bone formation and osseointegration are observed for all the samples. • In vitro conditions cause a significant change in the (Ca + Sr)/P ratio

  18. Synthesis, crystal structure and photochemistry of Hexakis(butan-1-aminium) heptamolybdate(VI) tetrahydrate

    Indian Academy of Sciences (India)

    SAVITA S KHANDOLKAR; ASHISH R NAIK; CHRISTIAN NÄTHER; WOLFGANG BENSCH; BIKSHANDARKOILR SRINIVASAN

    2016-11-01

    The synthesis, crystal structure, spectral characterization, photochemistry, electrochemical and thermal studies of the hexakis(butan-1-aminium) heptamolybdate(VI) tetrahydrate (1) are reported. Dissolution of a mixed mono-hepta compound (BuNH₃)₈[(Mo₇O₂₄)(MoO₄)]·3H₂O in water results in its transformation to the title compound viz., (BuNH₃)₆ [Mo₇O₂₄]·4H₂O 1 (BuNH₃ = butan-1-aminium). The structure of the title compound consists of two crystallographically unique [Mo₇O₂₄]⁶⁻ anions, twelve independent (BuNH₃)⁺ cations and eight unique lattice water molecules, all of which are interlinked with the aid of three varieties of Hbonding interactions. Solar irradiation of 1 results in the formation of a bis(μ2-oxo) bridged diheptamolybdateproduct. Electrochemical studies reveal the role of 1 in the photodimerization process. Thermal decomposition of 1 results in the formation of crystalline α-MoO₃.

  19. Synthesis of Superhydrophobic Films with Hierarchical Structures by Electron Irradiation of Inorganic Polymers

    International Nuclear Information System (INIS)

    Lotus-leaf-like superhydrophobic surfaces that have hierarchical mico/nano structures were synthesized by an electron irradiation of silicon-based inorganic polymer films and subsequent chemical treatment of the surface with a low surface-energy material. The polymer was spin-coated on silicon substrates and thin films of around 1 μm thickness were prepared. The polymer films were then irradiated with a 50 keV electron beam at the electron fluences ranging from 1.6 x 1017 cm-2 to 4.8 x 1017 cm-2. Interestingly, after the electron irradiation, irregular rough surfaces consisting of micropores and nanoparticles were created: nanoparticles comprise the remained walls of the micropores. X-ray photoelectron spectra revealed that the nanoparticles were silicon dioxide covered with carbon. The surfaces of the hierarchical structures were chemically treated with fluorosilane, a kind of low surface-energy material. After surface treatment, the water contact angle of the surfaces measured to be ca. 170 degree and the sliding angle becomes lower than 3 degree, showing superhydrophobic property and self-cleaning effect. The present techniques can be used for the synthesis of large-area superhydrophobic films or patterned superhydrophobic films for the applications to water-proof windows, microfluid devices, and biosensors

  20. Controlled synthesis of hyper-branched inorganic nanocrystals withrich three-dimensional structures

    Energy Technology Data Exchange (ETDEWEB)

    Kanaras, Antonios G.; Sonnichsen, Carsten; Liu, Haitao; Alivisatos, A. Paul

    2005-07-27

    Studies of crystal growth kinetics are tightly integrated with advances in the creation of new nanoscale inorganic building blocks and their functional assemblies 1-11. Recent examples include the development of semiconductor nanorods which have potential uses in solar cells 12-17, and the discovery of a light driven process to create noble metal particles with sharp corners that can be used in plasmonics 18,19. In the course of studying basic crystal growth kinetics we developed a process for preparing branched semiconductor nanocrystals such as tetrapods and inorganic dendrimers of precisely controlled generation 20,21. Here we report the discovery of a crystal growth kinetics regime in which a new class of hyper-branched nanocrystals are formed. The shapes range from 'thorny balls', to tree-like ramified structures, to delicate 'spider net'-like particles. These intricate shapes depend crucially on a delicate balance of branching and extension. The multitudes of resulting shapes recall the diverse shapes of snowflakes 22.The three dimensional nature of the branch points here, however, lead to even more complex arrangements than the two dimensionally branched structures observed in ice. These hyper-branched particles not only extend the available three-dimensional shapes in nanoparticle synthesis ,but also provide a tool to study growth kinetics by carefully observing and modeling particle morphology.

  1. Facile synthesis of diverse graphene nanomeshes based on simultaneous regulation of pore size and surface structure

    Science.gov (United States)

    Zhang, Jia; Song, Huaibing; Zeng, Dawen; Wang, Hao; Qin, Ziyu; Xu, Keng; Pang, Aimin; Xie, Changsheng

    2016-08-01

    Recently, graphene nanomesh (GNM) has attracted great attentions due to its unique porous structure, abundant active sites, finite band gap and possesses potential applications in the fields of electronics, gas sensor/storage, catalysis, etc. Therefore, diverse GNMs with different physical and chemical properties are required urgently to meet different applications. Herein we demonstrate a facile synthetic method based on the famous Fenton reaction to prepare GNM, by using economically fabricated graphene oxide (GO) as a starting material. By precisely controlling the reaction time, simultaneous regulation of pore size from 2.9 to 11.1 nm and surface structure can be realized. Ultimately, diverse GNMs with tunable band gap and work function can be obtained. Specially, the band gap decreases from 4.5-2.3 eV for GO, which is an insulator, to 3.9-1.24 eV for GNM-5 h, which approaches to a semiconductor. The dual nature of electrophilic addition and oxidizability of HO• is responsible for this controllable synthesis. This efficient, low-cost, inherently scalable synthetic method is suitable for provide diverse and optional GNMs, and may be generalized to a universal technique.

  2. Controllable synthesis of a novel hedgehog-like core/shell structure

    Science.gov (United States)

    Wang, Shumin; Tian, Hongwei; Pei, Yanhui; Meng, Qingnan; Chen, Jianli; Wang, Huan; Zeng, Yi; Zheng, Weitao; Liu, Yichun

    2012-02-01

    A novel hedgehog-like core/shell structure, consisting of a high density of vertically aligned graphene sheets and a thin graphene shell/a copper core (VGs-GS/CC), has been synthesized via a simple one-step synthesis route using radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD). Scanning and transmission electron microscopy investigations show that the morphology of this core/shell material could be controlled by deposition time. For a short deposition time, only multilayer graphene shell tightly surrounds the copper particle, while as the deposition time is relative long, graphene sheets extend from the surface of GS/CC. The GS can protect CC particles from oxidation. The growth mechanism for the obtained GS/CC and VGs-GS/CC has been revealed. Compared to VGs, VGs-GS/CC material exhibits a better electron field emission property. This investigation opens a possibility for designing a core/shell structure of different carbon-metal hybrid materials for a wide variety of practical applications.

  3. Strontium substituted hydroxyapatites: Synthesis and determination of their structural properties, in vitro and in vivo performance

    Energy Technology Data Exchange (ETDEWEB)

    Kaygili, Omer, E-mail: okaygili@firat.edu.tr [Department of Physics, Faculty of Science, Firat University, 23119 Elazig (Turkey); Keser, Serhat [Department of Chemistry, Faculty of Science, Firat University, 23119 Elazig (Turkey); Kom, Mustafa [Department of Surgery, Faculty of Veterinary Medicine, Firat University, 23119 Elazig (Turkey); Eroksuz, Yesari [Department of Pathology, Faculty of Veterinary Medicine, Firat University, 23119 Elazig (Turkey); Dorozhkin, Sergey V. [Kudrinskaja square 1-155, Moscow 123242 (Russian Federation); Ates, Tankut [Department of Physics, Faculty of Science, Firat University, 23119 Elazig (Turkey); Ozercan, Ibrahim H. [Department of Pathology, School of Medicine, Firat University, 23119 Elazig (Turkey); Tatar, Cengiz; Yakuphanoglu, Fahrettin [Department of Physics, Faculty of Science, Firat University, 23119 Elazig (Turkey)

    2015-10-01

    The objective of this study is to present a detailed report related to the synthesis and characterization of strontium substituted hydroxyapatites. Based on this purpose, hydroxyapatite (HAp) bioceramics with different amounts of strontium (e.g., 0, 0.45, 0.90, 1.35, 1.80 and 2.25 at.%) were prepared using a sol–gel method. The effects of Sr substitution on the structural properties and biocompatibility of the samples were studied by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques, in vitro and in vivo tests. All the samples composed of the nanoparticles ranging from 21 to 27 nm. The presence of Sr at low levels influenced the crystal size, crystallinity degree, lattice parameters and volume of the unit cell of the HAp. Both in vitro conditions and soaking period in simulated body fluid (SBF) significantly affected these properties. Especially, the (Ca + Sr)/P molar ratio gradually decreases with increasing soaking period in SBF. Animal experiments revealed the bone formation and osseointegration for all samples, and as compared with other groups, more reasonable, were observed for the sample with the lowest Sr content. - Highlights: • Sr content affects the structural properties of hydroxyapatite. • Bone formation and osseointegration are observed for all the samples. • In vitro conditions cause a significant change in the (Ca + Sr)/P ratio.

  4. Synthesis of -aryl--lactones and relationship: Structure – antifeedant and antifungal activity

    Indian Academy of Sciences (India)

    Andrzej Skrobiszewski; Witold Gładkowski; Paulina Walczak; Anna Gliszczyńska; Gabriela Maciejewska; Tomasz Klejdysz; Jan Nawrot; Czesław Wawrzeńczyk

    2015-04-01

    Eighteen racemic -aryl--lactones derived from simple aromatic aldehydes have been obtained in the chemical synthesis. Iodolactones (5c and 6c) were synthesized from ()-4-(benzo[][1′,3′]-dioxol-5′-yl)- but-3-en-2-one (1). Reductive dehalogenation of iodolactones 5a–c and 6a–c afforded -ethyl--lactones (7a–c, 8a–c) whereas the unsaturated lactones (9a–c, 10a–c) were obtained by dehydrohalogenation of iodolactones. All synthesized lactones were fully characterized by spectroscopic data (NMR, IR, HRMS) and subjected to the tests on the antifeedant activity towards Tribolium confusum, Trogoderma granarium and Sitophilus granaries as well to the tests on the antifungal activity towards four Fusarium species. The biological tests allowed to find some relationships between the structure and biological activity of the compounds studied. -Ethyl--lactones 7a–c, 8a–c and unsaturated lactones 9a–c, 10a-c were usually stronger antifeedants than their parent iodolactones 5a–c and 6a–c. trans-Iodolactones 6a–c were more active than cis isomers 5a-c both in antifeedant and antifungal assays. The structure of aromatic substituent was the key factor in antifungal activity. The lactones with benzo [][1,3]dioxole ring (5c, 6c, 7c, 8c, 9c) were the most active whereas those with unsubstituted benzene ring exhibited almost no activity.

  5. Influence of synthesis parameters on the electrical and structural properties of nanostructured BPO 4-Li 2O

    Science.gov (United States)

    Jak, M. J. G.; Kelder, E. M.; Everstein, S. J.; Schoonman, J.

    Li-doped BPO 4 is a promising ceramic Li +-ion conducting electrolyte for all-solid-state Li-ion batteries. The influence of the synthesis conditions on the structural and electrical properties of nanostructured Li-doped BPO 4 was investigated. The particle size of the material can be changed by varying the synthesis parameters. In order to investigate the relation between the particle size and the Li +-ion conductivity a series of samples was synthesized for temperatures between 150 and 600°C for 1.3 to 10 h. Two different synthesis routes were used and the composition, phase(s), Li +-ion conductivity, particle size, and particle morphology have been determined. As a result, single-phase Li-doped BPO 4 with a particle size of 30 nm was obtained at a synthesis temperature as low as 150°C and synthesis time of only 5 h. Furthermore, a smaller particle size results in a higher Li +-ion conductivity.

  6. A review on the synthesis, crystal growth, structure and physical properties of rare earth based quaternary intermetallic compounds

    Science.gov (United States)

    Mumbaraddi, Dundappa; Sarkar, Sumanta; Peter, Sebastian C.

    2016-04-01

    This review highlights the synthesis and crystal growth of quaternary intermetallic compounds based on rare earth metals. In the first part of this review, we highlight briefly about intermetallics and their versatile properties in comparison to the constituent elements. In the next part, we have discussed about various synthesis techniques with more focus on the metal flux technique towards the well shaped crystal growth of novel compounds. In the subsequent parts, several disordered quaternary compounds have been reviewed and then outlined most known ordered quaternary compounds with their complex structure. A special attention has been given to the ordered compounds with structural description and relation to the parent binary and ternary compounds. The importance of electronic and structural feature is highlighted as the key roles in designing these materials for emerging applications.

  7. Synthesis of gold structures by gold-binding peptide governed by concentration of gold ion and peptide.

    Science.gov (United States)

    Kim, Jungok; Kim, Dong-Hun; Lee, Sylvia J; Rheem, Youngwoo; Myung, Nosang V; Hur, Hor-Gil

    2016-08-01

    Although biological synthesis methods for the production of gold structures by microorganisms, plant extracts, proteins, and peptide have recently been introduced, there have been few reports pertaining to controlling their size and morphology. The gold ion and peptide concentrations affected on the size and uniformity of gold plates by a gold-binding peptide Midas-11. The higher concentration of gold ions produced a larger size of gold structures reached 125.5 μm, but an increased amount of Midas-11 produced a smaller size of gold platelets and increased the yield percentage of polygonal gold particles rather than platelets. The mechanisms governing factors controlling the production of gold structures were primarily related to nucleation and growth. These results indicate that the synthesis of gold architectures can be controlled by newly isolated and substituted peptides under different reaction conditions. PMID:27108675

  8. Synthesis and processing of intelligent cost-effective structures: a final review of the ARPA SPICES program

    Science.gov (United States)

    Jacobs, Jack H.

    1996-05-01

    The Synthesis and Processing of Intelligent Cost Effective Structures (SPICES) program is comprised of a consortium of industrial, academic and government labs working to develop cost effective material processing and synthesis technologies to enable new products using active vibration suppression and control devices to be brought to market. Since smart structures involve the integration of multiple engineering disciplines, it has been the objective of the consortium to establish cost effective design processes between this multi-organizational team for future incorporating of this new technology into each members respective product lines. Over the twenty-four month program many new improvements in sensors, actuators, modeling, manufacturing/integration and controls have been realized. The paper outlines the four phases of development in the program and the impact some of the key technologies will have on the smart structure development process in the future.

  9. Synthesis of Titanium Dioxide Nanocrystals with Controlled Crystal- and Micro-structures from Titanium Complexes

    OpenAIRE

    Makoto Kobayashi; Hideki Kato; Masato Kakihana

    2013-01-01

    Selective synthesis of titanium dioxide (TiO2) polymorphs including anatase, rutile, brookite and TiO2(B) by solvothermal treatment of water-soluble titanium complexes is described with a special focus on their morphological control. The utilization of water-soluble titanium complexes as a raw material allowed us to employ various additives in the synthesis of TiO2. As a result, the selective synthesis of the polymorphs, as well as diverse morphological control, was achieved.

  10. A Better Understanding of Protein Structure and Function by the Synthesis and Incorporation of Selenium- and Tellurium Containing Tryptophan Analogs

    Energy Technology Data Exchange (ETDEWEB)

    Helmey, Sherif Samir [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Bioscience Division; Belmont Univ., Nashville, TN (United States). Dept. of Chemistry and Physics; Rice, Ambrose Eugene [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Bioscience Division; Belmont Univ., Nashville, TN (United States). Dept. of Chemistry and Physics; Hatch, Duane Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Bioscience Division; Belmont Univ., Nashville, TN (United States). Dept. of Chemistry and Physics; Silks, Louis A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Bioscience Division; Marti-Arbona, Ricardo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Bioscience Division

    2016-08-17

    Unnatural heavy metal-containing amino acid analogs have shown to be very important in the analysis of protein structure, using methods such as X-ray crystallography, mass spectroscopy, and NMR spectroscopy. Synthesis and incorporation of selenium-containing methionine analogs has already been shown in the literature however with some drawbacks due to toxicity to host organisms. Thus synthesis of heavy metal tryptophan analogs should prove to be more effective since the amino acid tryptophan is naturally less abundant in many proteins. For example, bioincorporation of β-seleno[3,2-b]pyrrolyl-L-alanine ([4,5]SeTrp) and β-selenolo[2,3-b]pyrrolyl-L-alanine ([6,7]SeTrp) has been shown in the following proteins without structural or catalytic perturbations: human annexin V, barstar, and dihydrofolate reductase. The reported synthesis of these Se-containing analogs is currently not efficient for commercial purposes. Thus a more efficient, concise, high-yield synthesis of selenotryptophan, as well as the corresponding, tellurotryptophan, will be necessary for wide spread use of these unnatural amino acid analogs. This research will highlight our progress towards a synthetic route of both [6,7]SeTrp and [6,7]TeTrp, which ultimately will be used to study the effect on the catalytic activity of Lignin Peroxidase (LiP).

  11. Microwave-assisted hydrothermal synthesis of CePO{sub 4} nanostructures: Correlation between the structural and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Palma-Ramírez, D. [Instituto Politécnico Nacional, CICATA-Unidad Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico); Domínguez-Crespo, M.A., E-mail: mdominguezc@ipn.mx [Instituto Politécnico Nacional, CICATA-Unidad Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico); Torres-Huerta, A.M. [Instituto Politécnico Nacional, CICATA-Unidad Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico); Dorantes-Rosales, H. [Instituto Politécnico Nacional, ESIQIE, Departamento de Metalurgia, C.P. 07300 México D.F. (Mexico); Ramírez-Meneses, E. [Universidad Iberoamericana, Departamento de Ingeniería y Ciencias Químicas, Prolongación Paseo de la Reforma 880, Lomas de Santa Fe, C.P. 01219 México D.F. (Mexico); Rodríguez, E. [Instituto Politécnico Nacional, CICATA-Unidad Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico)

    2015-09-15

    Highlights: • An enhancement in the hydrothermal synthesis for obtaining of CePO{sub 4} is presented. • Microwave energy can replace the energy by convection for obtaining CePO{sub 4}. • CePO{sub 4} demonstrates to be an option to increase the optical properties of polymers. • Adjusting the pH, the sintering process is not necessary to obtain the desire phase. • CePO{sub 4} morphologies undergo evolution from nanorods to semispherical nanoparticles. - Abstract: In this work, the microwave-assisted hydrothermal method is proposed as an alternative to the synthesis of cerium phosphate (CePO{sub 4}) nanostructures to evaluate the influence of different synthesis parameters on both the structural and optical properties. In order to reach this goal, two different sets of experiments were designed, varying the reaction temperature (130 and 180 °C), synthesis time (15 and 30 min) and sintering temperature (400 and 600 °C), maintaining a constant pH = 3. Thereafter, two experimental conditions were selected to assess changes in the properties of CePO{sub 4} nanopowders with pH (1, 5, 9 and 11). The crystal structure and morphology of the nanostructures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. Diffuse reflectance properties of CePO{sub 4} with different microstructures were studied. The results demonstrated that by using the microwave-assisted hydrothermal method, the shape, size and structural phase of CePO{sub 4} can be modulated by using relatively low synthesis temperatures and short reaction times, and depending on pH, a sintering process is not needed to obtain either a desired phase or size. Under the selected experimental conditions, the materials underwent an evolution from nanorods to semispherical nanoparticles, accompanied by a phase transition from hexagonal to monoclinic.

  12. Microwave-assisted hydrothermal synthesis of CePO4 nanostructures: Correlation between the structural and optical properties

    International Nuclear Information System (INIS)

    Highlights: • An enhancement in the hydrothermal synthesis for obtaining of CePO4 is presented. • Microwave energy can replace the energy by convection for obtaining CePO4. • CePO4 demonstrates to be an option to increase the optical properties of polymers. • Adjusting the pH, the sintering process is not necessary to obtain the desire phase. • CePO4 morphologies undergo evolution from nanorods to semispherical nanoparticles. - Abstract: In this work, the microwave-assisted hydrothermal method is proposed as an alternative to the synthesis of cerium phosphate (CePO4) nanostructures to evaluate the influence of different synthesis parameters on both the structural and optical properties. In order to reach this goal, two different sets of experiments were designed, varying the reaction temperature (130 and 180 °C), synthesis time (15 and 30 min) and sintering temperature (400 and 600 °C), maintaining a constant pH = 3. Thereafter, two experimental conditions were selected to assess changes in the properties of CePO4 nanopowders with pH (1, 5, 9 and 11). The crystal structure and morphology of the nanostructures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. Diffuse reflectance properties of CePO4 with different microstructures were studied. The results demonstrated that by using the microwave-assisted hydrothermal method, the shape, size and structural phase of CePO4 can be modulated by using relatively low synthesis temperatures and short reaction times, and depending on pH, a sintering process is not needed to obtain either a desired phase or size. Under the selected experimental conditions, the materials underwent an evolution from nanorods to semispherical nanoparticles, accompanied by a phase transition from hexagonal to monoclinic

  13. Synthesis and structural evaluation of five coordination complexes of benzenepentacarboxylic acid with aza-donor ligands

    Science.gov (United States)

    Shimpi, Manishkumar R.; Biswas, Sharmita Nandy; Sarkar, Sohini; Pedireddi, V. R.

    2016-06-01

    Synthesis and structural features of five new coordination assemblies, [Co(bpyH)(H2O)5](BPCH)·(bpyH2)0.5·(H2O) (1a), [{Cu(H2O)3}·{Cu0.5(bpy)0.5(H2O)0.5}2(μ-BPCH)] (1b), [{Cd0.5(BPCH)}2·{Cd0.5(bpy)(H2O)2}2]·6(H2O) (1c), [Cu(BPCH2)(bpyeaH)]·2(H2O) (1d) and [Cd2 (bpyea)0.5(oxalate)0.5(μ-BPC) (H2O)]·(bpyeaH2)·2(H2O) (1e), have been reported. All the assemblies were prepared by co-crystallization of benzenepentacarboxylic acid (BPCH5) either with 4,4‧-bipyridine (bpy) or 1,2-bis(4-pyridyl)ethane (bpyea) in the presence of a transition metal ion (either Co(II), Cu(II) or Cd(II)) as the case may be. All the five compounds were synthesized by hydrothermal method and structures were determined by single crystal X-ray diffraction. All the obtained compounds, 1a-1e, exhibit distinct 3-D polymeric architectures either in the form of stacked layers or host-guest networks in which water molecules play a pivotal role providing additional stabilization by coordinate bonds as well as hydrogen bonds. Other non-covalent interactions such as C-H … π and π … π stacking also participate in the formation of exotic 3-D structures of these complexes.

  14. Synthesis and properties MFe2O4 (M = Fe, Co) nanoparticles and core-shell structures

    Science.gov (United States)

    Yelenich, O. V.; Solopan, S. O.; Greneche, J. M.; Belous, A. G.

    2015-08-01

    Individual Fe3-xO4 and CoFe2O4 nanoparticles, as well as Fe3-xO4/CoFe2O4 core/shell structures were synthesized by the method of co-precipitation from diethylene glycol solutions. Core/shell structure were synthesized with CoFe2O4-shell thickness of 1.0, 2.5 and 3.5 nm. X-ray diffraction patterns of individual nanoparticles and core/shell are similar and indicate that all synthesized samples have a cubic spinel structure. Compares Mössbauer studies of CoFe2O4, Fe3-xO4 nanoparticles indicate superparamagnetic properties at 300 K. It was shown that individual magnetite nanoparticles are transformed into maghemite through oxidation during the synthesis procedure, wherein the smallest nanoparticles are completely oxidized while a magnetite core does occur in the case of the largest nanoparticles. The Mössbauer spectra of core/shell nanoparticles with increasing CoFe2O4-shell thickness show a gradual decrease in the relative intensity of the quadrupole doublet and significant decrease of the mean isomer shift value at both RT and 77 K indicating a decrease of the superparamagnetic relaxation phenomena. Specific loss power for the prepared ferrofluids was experimentally calculated and it was determined that under influence of ac-magnetic field magnetic fluid based on individual CoFe2O4 and Fe3-xO4 particles are characterized by very low heating temperature, when magnetic fluids based on core/shell nanoparticles demonstrate higher heating effect.

  15. Nonlinear dynamic response analysis of localized damaged laminated composite structures in the context of component mode synthesis

    Science.gov (United States)

    Mahmoudi, S.; Trivaudey, F.; Bouhaddi, N.

    2015-07-01

    The aim of this study is the prediction of the dynamic response of damaged laminated composite structures in the context of component mode synthesis. Hence, a method of damage localization of complex structures is proposed. The dynamic behavior of transversely isotropic layers is expressed through elasticity coupled with damage based on an existing macro model for cracked structures. The damage is located only in some regions of the whole structure, which is decomposed on substructures. The incremental linear dynamic governing equations are obtained by using the classical linear Kirchhoff-Love theory of plates. Then, considering the damage-induced nonlinearity, the obtained nonlinear dynamic equations are solved in time domain. However, a detailed finite element modelling of such structure on the scale of localized damage would generate very high computational costs. To reduce this cost, Component Mode Synthesis method (CMS) is used for modelling a nonlinear fine-scale substructure damaged, connected to linear dynamic models of the remaining substructures, which can be condensed and not updated at each iteration. Numerical results show that the mechanical properties of the structure highly change when damage is taken into account. Under an impact load, damage increases and reaches its highest value with the maximum of the applied load and then remains unchanged. Besides, the eigenfrequencies of the damaged structure decrease comparing with those of an undamaged one. This methodology can be used for monitoring strategies and lifetime estimations of hybrid complex structures due to the damage state is known in space and time.

  16. Kinetic Studies of the Ring-Opening Bulk Polymerization of ɛ-Caprolactone Using a Novel Tin(II) Alkoxide Initiator

    Science.gov (United States)

    Kleawkla, Achara; Suksomran, Wallika; Charuchinda, Anodar; Molloy, Robert; Naksata, Wimol; Punyodom, Winita

    A novel initiator, tin(II) hexoxide, has been synthesized for use in the bulk ring-opening polymerization of ɛ-caprolactone at 140 °C and the kinetics studied using dilatometry. The effectiveness of the new initiator was compared alongside that of the corresponding conventional system, tin(II) octoate / 1-hexanol. The results showed that tin(II) hexoxide, although effective, took time to dissolve in the monomer due to its molecular aggregation, leading to a prolonged induction period. Despite this, first-order kinetics, a high conversion (>90%) and a polycaprolactone (PCL) molecular weight sufficiently high for melt processing were obtained. The small-scale melt spinning of PCL monofilament fibers and the effect of off-line drawing on their tensile properties is also briefly described. This work highlights the potential for the further development of more soluble tin(II) alkoxides for use as initiators which can offer greater reaction control in cyclic ester polymerization.

  17. Fluorinated Alkoxide-Based Magnesium-Ion Battery Electrolytes that Demonstrate Li-Ion-Battery-Like High Anodic Stability and Solution Conductivity.

    Science.gov (United States)

    Crowe, Adam J; Stringham, Kyle K; Bartlett, Bart M

    2016-09-01

    Based on DFT predictions, a series of highly soluble fluorinated alkoxide-based electrolytes were prepared, examined electrochemically, and reversibly cycled. The alcohols react with ethylmagnesium chloride to generate a fluoroalkoxy-magnesium chloride intermediate, which subsequently reacts with aluminum chloride to generate the electrolyte. Solutions starting from a 1,1,1,3,3,3-hexafluoro-2-methylpropan-2-ol precursor exhibit high anodic stability, 3.2 V vs Mg(2+/0), and a record 3.5 mS/cm solution conductivity. Excellent galvanostatic cycling and capacity retention (94%) is observed with more than 300 h of cycle time while employing the standard Chevrel phase-Mo6S8 cathode material.

  18. Inclusion of trans-resveratrol in methylated cyclodextrins: synthesis and solid-state structures

    Directory of Open Access Journals (Sweden)

    Lee Trollope

    2014-12-01

    Full Text Available The phytoalexin trans-resveratrol, 5-[(1E-2-(4-hydroxyphenylethenyl]-1,3-benzenediol, is a well-known, potent antioxidant having a variety of possible biomedical applications. However, its adverse physicochemical properties (low stability, poor aqueous solubility limit such applications and its inclusion in cyclodextrins (CDs has potential for addressing these shortcomings. Here, various methods of the attempted synthesis of inclusion complexes between trans-resveratrol and three methylated cyclodextrins (permethylated α-CD, permethylated β-CD and 2,6-dimethylated β-CD are described. Isolation of the corresponding crystalline 1:1 inclusion compounds enabled their full structure determination by X-ray analysis for the first time, revealing a variety of guest inclusion modes and unique supramolecular crystal packing motifs. The three crystalline inclusion complexes were also fully characterized by thermal analysis (hot stage microscopy, thermogravimetric analysis and differential scanning calorimetry. To complement the solid-state data, phase-solubility studies were conducted using a series of CDs (native and variously derivatised to establish their effect on the aqueous solubility of trans-resveratrol and to estimate association constants for complex formation.

  19. Synthesis, crystal structure and properties of magnesium and calcium salts of p-anisic acid

    Indian Academy of Sciences (India)

    Kiran T Dhavskar; Pooja H Bhargao; Bikshandarkoil R Srinivasan

    2016-03-01

    The synthesis, crystal structure and properties of the magnesium and calcium salts of p-anisic acid viz. [Mg(H2O)6](C8H7O3)2·2H2O (C8H7O3=p-anisate or 4-methoxybenzoate) (1) and [Ca(H2O)(C8H7O3)2] (2) are reported. The p-anisate ion is not coordinated to Mg(II) and functions as a charge balancing counter anion for the centrosymmetric octahedral [Mg(H2O)6]2+ unit in 1. The unique lattice water molecule links pairs of [Mg(H2O)6] 2+ cations and p-anisate anions with the aid of O-H···O interactions. The μ2-bridging bidentate and the μ3-bridging tetradentate binding modes of the crystallographically unique p-anisate ligands in (2) result in a two-dimensional (2-D) coordination polymer.

  20. Synthesis, structure and applications of [cis-dioxomolybdenum(VI)-(ONO)] type complexes

    Indian Academy of Sciences (India)

    Rajan Deepan Chakravarthy; Dillip Kumar Chand

    2011-03-01

    Oxo-molybdenum chemistry is of great interest since such units are found in the active sites of a majority of molybdo-enzymes. In order to mimic the biological systems, a number of oxo-molybdenum complexes have been synthesised and studied. This review describes synthesis, structure and applications of oxomolybdenum complexes particularly cis-MoO2(L)(D) where L stands for a dianionic tridentate ONO ligand and D for a donor solvent molecule/monodentate ligand. The ligand moieties are derived from Schiff base, hydrazide Schiff base and other related tridentate ligands L(H)2. The coordination geometry around the Mo center in these complexes can be best described as a distorted octahedron in which the ONO-tridentate ligand occupies meridional position with two anionic oxygen donors mutually trans and are cis to the oxygen centers of the cis-dioxo group. Mostly the applications of cis-MoO2-(ONO) type complexes seen in literature are oxo transfer reactions like epoxidation, sulfoxidation and phosphine oxidation reactions.

  1. Collagen-chitosan scaffold modified with Au and Ag nanoparticles: Synthesis and structure

    Science.gov (United States)

    Rubina, M. S.; Kamitov, E. E.; Zubavichus, Ya. V.; Peters, G. S.; Naumkin, A. V.; Suzer, S.; Vasil'kov, A. Yu.

    2016-03-01

    Nowadays, the dermal biomimetic scaffolds are widely used in regenerative medicine. Collagen-chitosan scaffold one of these materials possesses antibacterial activity, good compatibility with living tissues and has been already used as a wound-healing material. In this article, collagen-chitosan scaffolds modified with Ag and Au nanoparticles have been synthesized using novel method - the metal-vapor synthesis. The nanocomposite materials are characterized by XPS, TEM, SEM and synchrotron radiation-based X-ray techniques. According to XRD data, the mean size of the nanoparticles (NPs) is 10.5 nm and 20.2 nm in Au-Collagen-Chitosan (Au-CollCh) and Ag-Collagen-Chitosan (Ag-CollCh) scaffolds, respectively in fair agreement with the TEM data. SAXS analysis of the composites reveals an asymmetric size distribution peaked at 10 nm for Au-CollCh and 25 nm for Ag-CollCh indicative of particle's aggregation. According to SEM data, the metal-carrying scaffolds have layered structure and the nanoparticles are rather uniformly distributed on the surface material. XPS data indicate that the metallic nanoparticles are in their unoxidized/neutral states and dominantly stabilized within the chitosan-rich domains.

  2. Iron complexes of a bidentate picolyl-NHC ligand: synthesis, structure and reactivity.

    Science.gov (United States)

    Liang, Qiuming; Janes, Trevor; Gjergji, Xhoana; Song, Datong

    2016-09-21

    The synthesis, structure and reactivity of bidentate picolyl N-heterocyclic carbene (NHC) iron compounds were studied. Compounds [FeBr(HL)2]Br (1), [FeBr(HL)(HMDS)] (2) and [FeBr2(HL)] (3) (HL = 1-mesityl-3-(pyridin-2-ylmethyl)imidazol-1-ylidene, HMDS = hexamethyldisilazide) were prepared from H2LBr with suitable amounts of Fe(HMDS)2 or in situ prepared [Fe(HMDS)Br]. The deprotonation of 1 with 2 eq. of LiHMDS gave [FeL2] (4), featuring dearomatized pyridine moieties with exocyclic C-C double bonds. The protonation of 4 with 2 eq. of PPh3·HBr results in the formation of 1. Attempted deprotonation of 3 using benzyl Grignard as the base resulted in transmetalation products [FeBnBr(HL)] (5) and [FeBn2(HL)] (6). Exposure of 6 to CO resulted in the formation of diamagnetic compound [Fe(CO)3(HL)] (7) and dibenzyl ketone. Prolonged exposure of 7 to CO with heating induces pyridine dissociation, affording [Fe(CO)4(HL-κC)] (8). Treatment of compound 6 with an equimolar amount of p-methoxybenzyl bromide yielded homo- and cross-coupling products. PMID:27513216

  3. Lithography-free synthesis of nanostructured cobalt on Si (111 surfaces: structural and magnetic properties

    Directory of Open Access Journals (Sweden)

    Bounour-Bouzamouche W.

    2014-07-01

    Full Text Available We illustrate the concept of lithography-free synthesis and patterning of magnetic cobalt in the nanometric scale. Our elaboration method allows fabricating 2D architectures of cobalt and cobalt silicide onto silicon (111 surfaces. A continuous cobalt layer of 1, 3 and 10 nm thickness was first deposited by using thermoionic vacuum arc (TVA technology and then, thermally annealed on vacuum at temperatures from 450° C to 800° C. Surface structure was analyzed by atomic force and field emission-scanning electron microscopies. Above 750° C, regular triangular shape cobalt nanostructures are formed with pattern dimensions varying between 10 and 200 nm. Good control of shape and packing density could be achieved by adjusting the initial thickness and the substrate temperature. Magnetic properties were investigated by means of vibrating sample magnetometer (VSM technique. The evolution of the coercive field versus packing density and dimensions of the nanostructures was studied and compared to micromagnetic calculations. The observed nanostructures have been modelled by a series of shapes tending to a fractal curve.

  4. Synthesis and Structure-Activity Relationships of Substituted Urea Derivatives on Mouse Melanocortin Receptors.

    Science.gov (United States)

    Singh, Anamika; Kast, Johannes; Dirain, Marvin L S; Huang, Huisuo; Haskell-Luevano, Carrie

    2016-02-17

    The melanocortin system is involved in the regulation of several complex physiological functions. In particular, the melanocortin-3 and -4 receptors (MC3R/MC4R) have been demonstrated to regulate body weight, energy homeostasis, and feeding behavior. Synthetic and endogenous melanocortin agonists have been shown to be anorexigenic in rodent models. Herein, we report synthesis and structure-activity relationship (SAR) studies of 27 nonpeptide small molecule ligands based on an unsymmetrical substituted urea core. Three templates containing key residues from the lead compounds, showing diversity at three positions (R(1), R(2), R(3)), were designed and synthesized. The syntheses were optimized for efficient microwave-assisted chemistry that significantly reduced total syntheses time compared to a previously reported room temperature method. The pharmacological characterization of the compounds on the mouse melanocortin receptors identified compounds 1 and 12 with full agonist activity at the mMC4R, but no activity was observed at the mMC3R when tested up to 100 μM concentrations. The SAR identified compounds possessing aliphatic or saturated cyclic amines at the R(1) position, bulky aromatic groups at the R(2) position, and benzyl group at the R(3) position resulted in mMC4R selectivity over the mMC3R. The small molecule template and SAR knowledge from this series may be helpful in further design of MC3R/MC4R selective small molecule ligands. PMID:26645732

  5. A new family of metal borohydride guanidinate complexes: Synthesis, structures and hydrogen-storage properties

    Science.gov (United States)

    Wu, Hui; Zhou, Xiuquan; Rodriguez, Efrain E.; Zhou, Wei; Udovic, Terrence J.; Yildirim, Taner; Rush, John J.

    2016-10-01

    We report on a new class of complex hydrides: borohydride guanidinate complexes (MBH4·nCN3H5, M=Li, Mg, and Ca). They can be prepared via facile solid-state synthesis routes. Their crystal structures were successfully determined using a combination of X-ray diffraction, first-principles calculations and neutron vibrational spectroscopy. Among these compounds, Mg(BH4)2·6CN3H5 is composed of large complex Mg[CN3H5]62+ cations and surrounding BH4- ions, while Ca(BH4)2·2CN3H5 possesses layers of corner-sharing Ca[BH4]4(CN3H5)2 octahedra. Our dehydrogenation results show that ≈10 wt% hydrogen can be released from MBH4·nCN3H5 (M=Li, Mg, and Ca) at moderate temperatures with minimal ammonia and diborane contamination thanks to the synergistic effect of C-N bonds from guanidine and hydridic H from borohydrides leading to a weakening of the N-H bonds, thus impeding ammonia gas liberation. Further tuning the dehydrogenation with different cation species indicates that Mg(BH4)2·nCN3H5 can exhibit the optimum properties with nearly thermally neutral dehydrogenation and very high purity hydrogen release.

  6. The chemical synthesis of α-conotoxins and structurally modified analogs with enhanced biological stability.

    Science.gov (United States)

    Banerjee, Jayati; Gyanda, Reena; Chang, Yi-Pin; Armishaw, Christopher J

    2013-01-01

    α-Conotoxins are peptide neurotoxins isolated from the venom ducts of carnivorous marine cone snails that exhibit exquisite pharmacological potency and selectivity for various nicotinic acetylcholine receptor subtypes. As such, they are important research tools and drug leads for treating various diseases of the central nervous system, including pain and tobacco addiction. Despite their therapeutic potential, the chemical synthesis of α-conotoxins for use in structure-activity relationship studies is complicated by the possibility of three disulfide bond isomers, where inefficient folding methods can lead to a poor recovery of the pharmacologically active isomer. In order to achieve higher yields of the native isomer, especially in high-throughput syntheses it is necessary to select appropriate oxidative folding conditions. Moreover, the poor biochemical stability exhibited by α-conotoxins limits their general therapeutic applicability in vivo. Numerous strategies to enhance their stability including the substitution of disulfide bond with diselenide bond and N-to-C cyclization via an oligopeptide spacer have successfully overcome these limitations. This chapter describes methods for performing both selective and nonselective disulfide bond oxidation strategies for controlling the yields and formation of α-conotoxin disulfide bond isomers, as well as methods for the production of highly stable diselenide-containing and N-to-C cyclized conotoxin analogs. PMID:24014431

  7. Synthesis and Structure of a Novel Three-dimensional Organo-zincophosphite with Three Intersecting Channels

    Institute of Scientific and Technical Information of China (English)

    陈文斌; 李牛; 项寿鹤

    2005-01-01

    The hydrothermal synthesis and X-my single crystal diffraction analysis of a novel three-dimensional organo-zincophosphite, [HO(CH2)2NH3]2·[Zn3(HPO3)4], are described. The framework is built up from strictly alternating vertex-linked ZnO4 tetrahedron and HPO3 pseudo pyramid incorporating ethanolamine (EOA) cations into its channels. The structure is formed through 2nO4 tetrahedron connecting with two kinds of four-membered ring chains along different directions. There are three intersecting channels with eight-membered ring windows along [0 1 0], [0 4 15] and [0 -4 15], which have not been found in organo-zincophosphites before. Crystal data:[HO(CH2)2NH3]2·[Zn3(HPO3)4], Mr=640.21, Orthorhombic, Fdd2, a=2.8528nm, b=0.8426nm, c=1.6159nm,Z=8,V=3.884nm3, R1=0.0219,wR2=0.0544.

  8. Synthesis, structural characterisation and antibacterial activity of Ag+-doped fluorapatite nanomaterials prepared by neutralization method

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • The neutralization method has been used for synthesis of silver-doped fluorapatite powders. • Particles of silver-doped fluorapatite samples are of nano size and homogenous in composition. • The Ag+-doped fluorapatite samples showed antibacterial effect against Kllebsiela pneumoniae, Staphylococcus aureus and Micrococcus luteus. • AFM studies showed that silver-doped sample causes considerable morphological changes of tested bacterial cells. - Abstract: Silver doped fluorapatite nanopowders were synthesised by neutralization method, which consists of dissolving Ag2O in solution of HF and H3PO4 and addition to suspension of Ca(OH)2. The powder XRD, SEM and FTIR studies indicated the formation of a fluorapatite nanomaterials with average length of the particles is about 80 nm and a width of about 15 nm. The FTIR studies show that carbonate content in samples is very small and carbonte ions substitute both phosphate and hydroxyl groups in the crystal structure of samples, forming AB-type fluorapatite. Antibacterial studies have demonstrated that all Ag+-doped fluorapatite samples exhibit bactericidal effect against pathogens: Staphylococcus aureus, Micrococcus luteus and Kllebsiela pneumoniae. Antibacterial activity increased with the increase of Ag+ in the samples. The atomic force microscopy studies revealed extensive damage to the bacterial cell envelops in the presence of Ag+-doped fluorapatite particles which may lead to their death. The synthesized Ag+-doped fluorapatite nanomaterials are promising as antibacterial biomaterials in orthopedics and dentistry

  9. Allenylphosphonates with a 1,3,2-dioxaphosphorinane ring: Synthesis, structures, stability and utility

    Indian Academy of Sciences (India)

    N N Bhuvan Kumar; Manab Chakravarty; N Satish Kumar; K V Sajna; K C Kumara Swamy

    2009-01-01

    Synthesis, structures and stability (thermal and air) of allenylphosphonates of the type (OCH2CMe2CH2O)P(O)C(R)=C=CR'R" and [R"R'C=C=C(R)P(O)(OCH2)2]2C are discussed. Thermally activated dimerization (cycloaddition) of (OCH2CMe2CH2O)P(O)C(H)=C=CMe2 leads to the phosphonocyclobutane [(OCH2CMe2CH2O)P(O)C(H)=]2[C-CMe2]2 (18). Many of these allenes undergo addition of diethylamine to lead to enaminophosphonates that are readily hydrolysed by water to lead to -ketophosphonates. The latter compounds are useful as Horner-Wadsworth-Emmons (HWE) reagents. Molecular structures of (OCH2CMe2CH2O)P(O)C(CH2OH)=C=CH2 (6), [H2C=C=C(H)P(O)(OCH2)2]2C (9), (OCH2CMe2CH2O)P(O)CH=C=CH2 (12), [(OCH2CMe2CH2O)P(O)C(H)=]2[C-CMe2]2 (18), and the -ketophosphonate (OCH2CMe2CH2O)P(O)CH2)-C(O)CHMe2 (24) have been determined. In compound 6, intermolecular hydrogen bonding between the phosphoryl oxygen and the hydroxyl group leading to an infinite chain is observed. In 6, there is a significant deviation (ca 7°) from the orthogonality expected between the planes containing 4 atoms of (a) H2C=C and (b) C=C(H)P in the allene part. In 9, weak C-H…O interaction between the phosphoryl oxygen atom and a CH2 proton of the six-membered ring is present.

  10. Synthesis, characterization and nano-structuration of poly-thiophene derivatives for organic photovoltaic solar cells

    International Nuclear Information System (INIS)

    This work is devoted to the synthesis of poly-thiophene derivatives with low bandgap and preserving high oxidation potential. Di-substituted thiophenes and 'Donor-Acceptor' bi-thiophenes were synthesized and then polymerized. The side chains of these polymers, donor or acceptor, were modified in order to tune the properties of material as well from the optical point of view as electrochemical. These polymers were also tested in blend with PCBM in bulk-heterojunction photovoltaic cells. Voc delivered by the devices showed a linear dependence according to the potential of oxidation of the polymers. Copolymers containing cyano-thiophene and alkyl- or alkoxy-thiophene showed values of 0.8 V. However, in spite of power conversion efficiency of 1 %, these performances remain lower than the one obtained with the P3HT. Optimizations in terms of morphology are certainly necessary. Indeed, the morphology of the active layer plays a key role in obtaining high power conversion efficiency. An original technique of nano-structuration of the polymer on a nano-metric scale was developed during this work, leading to the development of fibrillary P3HT. These nano-structures, presenting an important degree of order, are formed spontaneously in solution. Their rate compared to amorphous material is perfectly controllable and adjustable in solution and in solid state. Measurements of mobilities show a strong improvement of the transport of load within these fibrillary layers compared to a traditional film of P3HT obtained without annealing. Power conversion efficiencies of 3.6 % on glass and 3.3 % on plastic were reached without annealing. (author)

  11. Alstoscholarisines H-J, Indole Alkaloids from Alstonia scholaris: Structural Evaluation and Bioinspired Synthesis of Alstoscholarisine H.

    Science.gov (United States)

    Pan, Zhiqiang; Qin, Xu-Jie; Liu, Ya-Ping; Wu, Ting; Luo, Xiao-Dong; Xia, Chengfeng

    2016-02-19

    Alstoscholarisines H-J (1-3), new monoterpenoid indole alkaloids with an unprecedented skeleton created via the formation of a C-3/N-1 bond, were isolated from Alstonia scholaris. Their structures were established by extensive spectroscopic analyses and the assessment of single-crystal X-ray diffraction data. The total synthesis of alstoscholarisine H was achieved via the regioselective nucleophilic addition of pyridinium through a bioinspired iminium ion intermediate followed by Pictet-Spengler-like cyclization. PMID:26800290

  12. Synthesis, structure and solvatochromic properties of some novel 5-arylazo-6-hydroxy-4-phenyl-3-cyano-2-pyridone dyes

    OpenAIRE

    Alimmari Adel; Mijin Dušan; Vukićević Radovan; Božić Bojan; Valentić Nataša; Vitnik Vesna; Vitnik Željko; Ušćumlić Gordana

    2012-01-01

    Abstract Background A series of some novel arylazo pyridone dyes was synthesized from the corresponding diazonium salt and 6-hydroxy-4-phenyl-3-cyano-2-pyridone using a classical reaction for the synthesis of the azo compounds. Results The structure of the dyes was confirmed by UV-vis, FT-IR, 1H NMR and 13C NMR spectroscopic techniques and elemental analysis. The solvatochromic behavior of the dyes was evaluated with respect to their visible absorption properties in various solvents. Conclusi...

  13. Synthesis, biological evaluation and structure-activity relationships of new quinoxaline derivatives as anti-Plasmodium falciparum agents

    OpenAIRE

    Gil, Ana Gloria; Pabón, Adriana; Galiano, Silvia; Burguete, M. Isabel; Pérez-Silanes, Silvia; Deharo, Eric; Monge, Antonio; Aldana Ignacio

    2014-01-01

    We report the synthesis and antimalarial activities of eighteen quinoxaline and quinoxaline 1,4-di-N-oxide derivatives, eight of which are completely novel. Compounds 1a and 2a were the most active against Plasmodium falciparum strains. Structure-activity relationships demonstrated the importance of an enone moiety linked to the quinoxaline ring. © 2014 by the authors; licensee MDPI, Basel, Switzerland.

  14. How the method of synthesis governs the local and global structure of zinc aluminum layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Pushparaj, Suraj Shiv Charan; Forano, Claude; Prevot, Vanessa; Lipton, Andrew S.; Rees, Gregory; Hanna, John V.; Nielsen, Ulla Gro

    2015-11-10

    A series of zinc aluminum layered double hydroxides (ZnAl LDHs), [Zn1-xAlx (OH)2Ax,nH2O with A = NO3-, Cl- or CO3] were prepared by the urea and co-precipitation synthesis methods, which allowed for a detailed investigation on how synthesis parameters such as pH, metal ion concentration and post synthesis treatment influence the local and global structure of the LDH product. Information about sample composition, purity, defects and other structural aspects of the LDH products were obtained from powder X-ray diffraction, transmission electron microscopy, micro-Raman, and elemental analysis, as well as solid state 1H, 27Al and 67Zn NMR spectroscopy. Our results show that the urea method results in LDHs, which on the global scale are highly crystalline LDHs, whereas solid state NMR shows the different local environments indicating local disorder most likely linked to the presence of Al-rich phases. However, these Alrich phases are not detected by global range techniques, as they either defects within the LDH particles or separate phase(s) associated with LDHs. In contrast, samples prepared by coprecipitation especially synthesized under careful pH control and subsequently hydrothermal treated have high local order and good crystallinity (particle size). Our results show that both molecular level and macroscopic techniques are needed to assess the composition of LDHs, as the conventional PXRD and TEM analysis of LDHs failed to identify the many structural defects and/or amorphous phases.

  15. DNA Synthesis in the Giant Nuclei of Insects - Control Machinery and Structures Observed in the Silk-Producing Gland of Bombyx Mori

    International Nuclear Information System (INIS)

    The existence in many insect organs of giant nuclei without visible chromosomes raises the question of possible homologies between the chromatin structures of these nuclei and those of polytene nuclei or common euploid cells. Studies have been made of the nuclei in the silk-producing gland of Bombyx mori. The DNA synthesis is cyclic. During the third stage there are three successive synthesis cycles, which appear to be relatively autonomous in the individual nuclei. For more than 24 hours after moulting, however, synthesis is greatly reduced; moulting factors thus cause synchronization of all the nuclei. This leads to the conclusion that the triggering of a synthesis cycle is controlled by general factors external to the cell. At the end of larval development, DNA synthesis is suspended at the moment when large-scale secretion of silk begins. Evaluation of the pool of endogenic precursors of DNA shows that it is considerably reduced at the end of the DNA synthesis period. The hypothesis proposed is that large-scale synthesis of fibroin requires polarization of the metabolism, hence the depletion of the nucleotide pool and the end of DNA synthesis. DNA synthesis within a single nucleus is to some extent asynchronic. In particular, a well-defined, delayed-synthesis structure visible only in the female seems to be a possible homologue of a sex chromosome. Other asynchronisms are also apparent, though less clearly. Functional studies thus allow the supposition that in the giant nucleus replication units retain an individuality comparable to that of a polytene chromosome. These observations together lead to the conclusion that a nucleus in the silk-producing gland has physiological and structural characteristics similar to those of a polytene nucleus, differing from it essentially in the lesser degree of condensation of its structures. (author)

  16. Silver nanoplates with ground or metastable structures obtained from template-free two-phase aqueous/organic synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Zhelev, Doncho V., E-mail: dontcho.jelev@nih.gov; Zheleva, Tsvetanka S. [Army Research Laboratory, 2800 Adelphi, Maryland 20783 (United States)

    2014-01-28

    Silver has unique electrical, catalytic, and plasmonic characteristics and has been widely sought for fabrication of nanostructures. The properties of silver nanostructures are intimately coupled to the structure of silver crystals. Two crystal structures are known for silver: the stable (ground) state cubic face centered 3C-Ag structure and the metastable hexagonal 4H-Ag structure. Recently, Chackraborty et al. [J. Phys.: Condens. Matter 23, 325401 (2011)] discovered a low density, highly reactive metastable hexagonal 2H-Ag structure accessible during electrodeposition of silver nanowires in porous anodic alumina templates. This 2H-Ag structure has enhanced electrical and catalytic characteristics. In the present work we report template-free synthesis of silver nanoplates with the metastable 2H-Ag crystal structure, which appears together with the ground 3C-Ag and the metastable 4H-Ag structures in a two-phase solution synthesis with citric acid as the capping agent. The capacity of citric acid to stabilize both the stable and the metastable structures is explained by its preferential binding to the close packed facets of Ag crystals, which are the (111) planes for 3C-Ag and the (0001) planes for 4H-Ag and 2H-Ag. Nanoplate morphology and structure are characterized using scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. The synthesized nanoplates have thickness from 15 to 17 nm and edge length from 1 to 10 μm. Transmission electron microscopy selected area electron diffraction is used to uniquely identify and distinguish between nanoplates with 2H-Ag or 4H-Ag or 3C-Ag structures.

  17. Synthesis, structure, and electronic structure calculation of a new centrosymmetric borate Pb2O[BO2(OH)] based on anion-centered OPb4 tetrahedra

    Science.gov (United States)

    Sun, Feng; Wang, Li; Stoumpos, Constantinos C.

    2016-08-01

    The synthesis, structure, and characterization of a new centrosymmetric borate Pb2O[BO2(OH)] based on anion-centered OPb4 tetrahedra are reported. Pb2O[BO2(OH)] crystallizes in monoclinic space group C2/m with a=12.725(7) Å, b=5.698(3) Å, c=7.344(4) Å, β=116.277(6)°. The electronic band structure and density of states of Pb2O[BO2(OH)] have been calculated via the density functional theory (DFT). Electron density difference calculation indicates that lone-pair electrons of Pb2+ cation should be stereoactive.

  18. An improved analysis/synthesis capability based on dual methods - ACCESS 3. [for minimum weight design of structures

    Science.gov (United States)

    Schmit, L. A.; Fleury, C.

    1979-01-01

    Approximation concepts and dual method algorithms are combined to create a new method for minimum weight design of structural systems. Approximation concepts convert the basic mathematical programming statement of the structural synthesis problem into a sequence of explicit primal problems of separable form. These problems are solved by constructing explicit dual functions, which are maximized subject to nonnegativity constraints. The dual method is successfully extended to deal with pure discrete and mixed continuous-discrete design variable problems. The power of the method presented is illustrated with numerical results for example problems, including a thin delta wing with fiber composite skins.

  19. Synthesis, X-ray structure and N–H…O interactions in 1,3-diphenyl-urea

    Indian Academy of Sciences (India)

    Rajnikant; Dinesh; M B Deshmukh; Kamni

    2006-06-01

    The synthesis, X-ray structure and role of intermolecular interactions have been studied in case of 1,3-diphenyl-urea, owing to its medicinal importance. The compound crystallizes in orthorhombic crystal system (space group, 21) with unit cell parameters, = 9.118(3), = 10.558(2), = 11.780(3) Å and = 4. The structure has been solved by direct methods and refined to a final -value of 0.0316. The oxygen atom of the carbonyl group is responsible for the existence of two N–H…O intermolecular interactions.

  20. Structures and performance of Rh—Mo—K/Al2O3 catalysts used for mixed alcohol synthesis from synthesis gas

    Institute of Scientific and Technical Information of China (English)

    Zhong-ruiLi; Yi-luFu; 等

    1999-01-01

    A series of rhodium-modified Mo-K/Al2O3 catalyst samples was prepared by varying the rhodium loading between 0 and 1.0 wt% and maintaining molybdenum and potassium contents as constants.The structures of the samples were charaterized by techniques of XRD.LRS.TPR,XPS and EXAFS and correlated to the catalytic properties of the samples for alcohol synthesis from synthesis gas,It was found that.in the oxidic rhodium-modified samples.a strong interaction of the rhodium modifier with the supported K-Mo-O species occurs.This interaction facilitates the sulfidation and reduction of the supported oxo-molybdenum and leads to a decrease in the size of the molybdenum species and stabilization of the cationic rhodium species on the samples during sulfidation.Upon sulfidation.The sulfided molybdenum species in the rhodium-free sample is manly present as large pateches of MoS2-like slabs with their basal sulfur planes interacting with the support surface.With the modirication of rhodium to the samples.The supported MoS2-like species becomes highly dispersed.as revealed by the decrease in the average size of the sulfided molybdenum species.The interaction of the rhodium species with the molybdenum somponent may cause the basal planes of the MoS2-like species to become oriented perpendicular to the support surface due to favorable bonding of the MoS2edge planes to the support through Mo-O-Al bonds.In comparison with the sulfided sample free of rhodium.the properties of the rhodium-modified samples for alcohol synthesis from synthesis gas are much improved.It most probably results from the synergic interaction of the rhodium with the molybdenum species that gives rise to the appearance of the catalytically active surfaces of sites.The co-existence of cationic and metallic rhodium stabilized by this interaction may be responsible for the increased selectivity for the formation of C2+ alcohols.

  1. Constitutional Isomers of Dendrimer-like Star Polymers: Design, Synthesis and Conformational and Structural Properties; TOPICAL

    International Nuclear Information System (INIS)

    The design, synthesis and solution properties of six constitutional isomers of dendrimer-like star polymers is described. Each of the polymers have comparable molecular weights ((approx) 80,000 g/mol), narrow polydispersities ( and lt; 1.19) and an identical number of branching junctures (45) and surface hydroxyl functionalities (48). The only difference in the six isomers is the placement of the branching junctures. The polymers are constructed from high molecular weight poly(e-caprolactone) with branching junctures derived from 2,2'-bis(hydroxylmethyl) propionic acid (bis-MPA) emanating from a central core. The use of various generations of dendritic initiators and dendrons coupled with the ring opening polymerization of e-caprolactones allowed a modular approach to the dendrimer-like star polymer isomers. The most pronounced effects on the physical properties/morphology and hydrodynamic volume was for those polymers in which the branching was distributed throughout the sample in a dendrimer-like fashion. The versatility of this approach has provided the possibility of understanding the relationship between architecture and physical properties. Dynamic light scattering and small angle X-ray scattering techniques were used to determine the hydrodynamic radius Rh and radius of gyration Rg respectively. The relationship between Rg and molecular weight was indicative of a compact star-like structure, and did not show advanced bias towards either the dense core or dense shell models. The radial density distribution of the isomers was therefore modeled according to a many arm star polymer, and good agreement was found with experimental measures of Rh/Rg

  2. Controlled synthesis and structure tunability of photocatalytically active mesoporous metal-based stannate nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Caihong [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136 (United States); Chen, Haiyan [Mineral Physics Institute, Stony Brook University, Stony Brook, NY 11794 (United States); Ren, Zheng [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136 (United States); Dardona, Sameh; Piech, Martin [Department of Physical Sciences, United Technologies Research Center, East Hartford, CT 06108 (United States); Gao, Haiyong [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136 (United States); Gao, Pu-Xian, E-mail: puxian.gao@ims.uconn.edu [Department of Materials Science and Engineering and Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136 (United States)

    2014-03-01

    Highlights: • A generic process has been developed for fabricating metal stannate nanostructures by simple substitution solution reactions followed by post-thermal treatments. • Band energy alignment, high carrier mobility and large specific surface area are found to play key roles for the enabled high efficiency in stannate nanostructured photocatalysts. • The developed process can be easily extended to the fabrication of other complex metal oxide nanostructures. - Abstract: A variety of stannate nanostructures have been fabricated for UV photocatalysis, including zinc- and cadmium-based stannates. As the template nanostructures, high surface-area mesoporous metal hydroxystannate [ZnSn(OH){sub 6} and CdSn(OH){sub 6}] nanoparticles (>100 m{sup 2}/g) have been synthesized using a simple, low-temperature substitution chemical process with controlled porosity, morphology and crystallinity. Post-synthetic thermal treatments were employed to obtain amorphous ZnSnO{sub 3}, CdSnO{sub 3}, ilmenite CdSnO{sub 3}, and crystalline Zn{sub 2}SnO{sub 4}–SnO{sub 2} nanoparticles. As a result, the band gaps can be tuned from 5.4 eV to 3.3 eV and from 4.9 eV to 2.1 eV for Zn-based and Cd-based stannates, respectively. Amorphous ZnSnO{sub 3} porous nanoparticles showed highest activity toward dye degradation under UV illumination followed by the Zn{sub 2}SnO{sub 4}-SnO{sub 2} and ilmenite CdSnO{sub 3} nanostructures due to their beneficial band structure alignment, high conductivities, and high specific surface areas. This study may provide an important strategy for high throughput synthesis and screening of functional complex metal oxide nanomaterials, while the enabled stannate nanomaterials could be utilized in various applications.

  3. Synthesis under Micromave Irradition and Crystal Structure of 4'-Acetylbenzo-15 -crown-5thiosemicarbazone

    Institute of Scientific and Technical Information of China (English)

    ZHANG You-ming; ZONG Guo-qiang; WEI Tai-bao

    2004-01-01

    The title compound is a bifunctional receptors including a thiourea group and a crown ether ring. Due to many possible potentials as a new class of reagents for membrane transports,ion-selective electrodes as well as reaction catalysts, the design and synthesis of bifunctional receptors for simultaneous binding of cations and anions is of ongoning interest in srprarnolecular chemistry1-5. In bifunctional receptors, the binding sites for anions and cations are covalently linked so as to exhibit allosteric or cooperative complexation where the binding affinity for anions(cations)is modified as a result of the cation(anion) complexation.Literature[6] reported that the ability of the thiourea group to bind anions is significantly enhanced when Na+ is bound to the crown moiety. To date, however only a few receptors of this class have been reported.6-8In this paper, we report an improved procedure under microwave irradiation that gives higher yields of title compound and needs fewer reaction times than traditional method.The structure of this compound was determined by IR ,element analysis and X-ray analysis.Scheme 1 The reaction equationThe crystal belongs to triclinic crystal system, P-1 space group, a=0.9547(0)nm, b=1.3637(3)nm,c=1.6029(3)nm, α =75.33(3) , β =83.62(3) , γ =70.99(3) ,Z=4,Dc=1.335g/cm3,F(000)=816,R1= 0.0557 ,wR2=0.1281. It is assembled into a three-dimensionalsupramolecule by intermolecular hydrogen bonds.

  4. Electrochemical and structural analysis of the RE3+:CeO2 nanopowders from combustion synthesis

    International Nuclear Information System (INIS)

    Highlights: • Rare earth elements doped ceria were synthesized by citrate nitrate auto-combustion method. • XRD revealed that they crystallize as single-phase cubic fluorite structure. • PL, FTIR and RAMAN studies were carried to analyze the existence of functional groups. • The morphology of the nanoparticles and compacts were analyzed by SEM and HRTEM. • Cyclic voltammetry (CV) for RE3+:CeO2 were measured and compared. - Abstract: The reported article deals with the synthesis and characterization of rare earth ions doped ceria (RE3+:CeO2) nanopowders from citrate nitrate auto-combustion route. The crystalline nature and lattice planes of the nanocrystalline RE3+:CeO2 powders were analyzed by X-ray diffraction (XRD) and Selected Area Electron Diffraction (SAED) profile fit. The excited state absorption (ESA) and energy transfer up-conversion (ETU) were studied by photoluminescence (PL) measurement. The spectroscopic properties of the powders were studied using Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The surface morphology, average size, distribution and orientation of the lattice planes of the nanoparticles were studied by using scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The size of RE3+:CeO2 nanoparticles were found to be in the range from 15 to 30 nm which has good agreement with the HRTEM results. The changes in current density with increasing sweep scan potential of the doped ceria powders were studied by cyclic voltammetry (CV) analysis. The specific capacitance range of the rare earths doped ceria of Er:CeO2, Pr:CeO2, Yr:CeO2 and Nd:CeO2 were calculated as (12.9–86.5), (20–72.4), (80–375) and (0.92–4.22) respectively

  5. Combustion synthesis of molybdenum silicides and borosilicides for ultrahigh-temperature structural applications

    Science.gov (United States)

    Alam, Mohammad Shafiul

    Molybdenum silicides and borosilicides are promising structural materials for gas-turbine power plants. A major challenge, however, is to simultaneously achieve high oxidation resistance and acceptable mechanical properties at high temperatures. For example, molybdenum disilicide (MoSi2) has excellent oxidation resistance and poor mechanical properties, while Mo-rich silicides such as Mo5Si3 (called T 1) have much better mechanical properties but poor oxidation resistance. One approach is based on the fabrication of MoSi2-T 1 composites that combine high oxidation resistance of MoSi2 and good mechanical properties of T1. Another approach involves the addition of boron to Mo-rich silicides for improving their oxidation resistance through the formation of a borosilicate surface layer. In particular, Mo 5SiB2 (called T2) phase is considered as an attractive material. In the thesis, MoSi2-T1 composites and materials based on T2 phase are obtained by mechanically activated SHS. Use of SHS compaction (quasi-isostatic pressing) significantly improves oxidation resistance of the obtained MoSi2-T1 composites. Combustion of Mo-Si-B mixtures for the formation of T2 phase becomes possible if the composition is designed for the addition of more exothermic reactions leading to the formation of molybdenum boride. These mixtures exhibit spin combustion, the characteristics of which are in good agreement with the spin combustion theory. Oxidation resistance of the obtained Mo-Si-B materials is independent on the concentration of Mo phase in the products so that the materials with a higher Mo content are preferable because of better mechanical properties. Also, T2 phase has been obtained by the chemical oven combustion synthesis technique.

  6. Synthesis and Structure Characterization of Phenol-Urea-Formaldehyde Resins in the Presence of Magnesium Oxide as Catalyst

    Directory of Open Access Journals (Sweden)

    Dong-Bin Fan

    2014-08-01

    Full Text Available The objective of this research was to provide a useful approach of polymer synthesis for accelerating the fast cure of phenol-urea-formaldehyde (PUF resin as wood adhesive by optimizing its structure and composition. The PUF resins containing high contents of very reactive groups such as para-methylol groups were synthesized by reacting methylolurea, phenol, and formaldehyde in the presence of magnesium oxide (MgO as catalyst. The effects of synthesis parameters including F/(P + U, OH/P, and MgO/P mole ratios on the structure, composition, curing characteristics, and their relationships of PUF resins were investigated. The results indicated that MgO seemed to be an efficacious catalyst for PUF resin synthesis and promote its faster cure. The increase in the F/(P + U mole ratio or/and OH/P mole ratio appeared to be beneficial for the formation of para-methylol groups and cocondensed methylene linkages between phenolic methylol groups and urea units, and for the removal of unreacted urea. In case of Catalyst/P mole ratio, an appropriate dosage of added metal-ion was very important for synthesizing the high-content reactive groups of PUF resins, otherwise leading to the reverse effects.

  7. Structural characterization of birnessite: influence of the way of synthesis; Caracterisation structurale de la birnessite: influence du protocole de synthese

    Energy Technology Data Exchange (ETDEWEB)

    Gaillot, A.C.

    2002-01-15

    Birnessite is a lamellar manganese oxide whose layers are built up of edge sharing MnO{sub 6} octahedra. The presence of hetero-valent Mn cations and/or of vacant sites in these layers leads to a charge deficit compensated for by the presence of hydrated cations in the interlayer space. Because of their high specific area and of their strong oxidative character, these ubiquitous manganese oxides play a fundamental role in the fate of organic and metallic pollutants in the environment, but our imperfect knowledge of their structure limits the understanding and the modeling of this impact. This study aimed at classifying all different kinds of birnessite obtained using existing synthesis protocols according to two relevant criteria: layer symmetry and layer stacking mode, and at determining the structure of several essential varieties using X-ray and electron diffraction. Layers of hydrothermal birnessite contain vacant sites and, as a result, possess an hexagonal symmetry. Their stacking mode is 3R. In high-temperature birnessites, adjacent layers have an opposite orientation, which results in a two-layer polytype. The symmetry of these layers, linked to the origin of the layer charge deficit, depends on the temperature of synthesis. At 800 C the presence of vacant sites results in an hexagonal symmetry (2H polytype). At 1000 C, the layer charge deficit originates from the presence of Mn{sup 3+} cations in the layer lowering the layer symmetry (2O polytype). A variety of chemical and structural heterogeneities was also described in these samples, along with the occurrence of a new type of structural disorder. Finally we proved both the fundamental link between the origin of the layer charge and the layer symmetry, and the influence of physico-chemical parameters during synthesis (temperature, average manganese oxidation degree, nature of the interlayer cation) on the structure of the obtained compound. The chemical and thermal stabilities of these birnessites are

  8. Synthesis, structural and electrochemical properties of sodium nickel phosphate for energy storage devices

    Science.gov (United States)

    Minakshi, Manickam; Mitchell, David; Jones, Rob; Alenazey, Feraih; Watcharatharapong, Teeraphat; Chakraborty, Sudip; Ahuja, Rajeev

    2016-05-01

    Electrochemical energy production and storage at large scale and low cost, is a critical bottleneck in renewable energy systems. Oxides and lithium transition metal phosphates have been researched for over two decades and many technologies based on them exist. Much less work has been done investigating the use of sodium phosphates for energy storage. In this work, the synthesis of sodium nickel phosphate at different temperatures is performed and its performance evaluated for supercapacitor applications. The electronic properties of polycrystalline NaNiPO4 polymorphs, triphylite and maricite, t- and m-NaNiPO4 are calculated by means of first-principle calculations based on spin-polarized Density Functional Theory (DFT). The structure and morphology of the polymorphs were characterized and validated experimentally and it is shown that the sodium nickel phosphate (NaNiPO4) exists in two different forms (triphylite and maricite), depending on the synthetic temperature (300-550 °C). The as-prepared and triphylite forms of NaNiPO4vs. activated carbon in 2 M NaOH exhibit the maximum specific capacitance of 125 F g-1 and 85 F g-1 respectively, at 1 A g-1 both having excellent cycling stability with retention of 99% capacity up to 2000 cycles. The maricite form showed 70 F g-1 with a significant drop in capacity after just 50 cycles. These results reveal that the synthesized triphylite showed a high performance energy density of 44 Wh kg-1 which is attributed to the hierarchical structure of the porous NaNiPO4 nanosheets. At a higher temperature (>400 °C) the maricite form of NaNiPO4 possesses a nanoplate-like (coarse and blocky) structure with a large skewing at the intermediate frequency that is not tolerant of cycling. Computed results for the sodium nickel phosphate polymorphs and the electrochemical experimental results are in good agreement.Electrochemical energy production and storage at large scale and low cost, is a critical bottleneck in renewable energy

  9. Morphology-controlled two-step synthesis and electrochemical studies on hierarchically structured LiCoPO4

    Science.gov (United States)

    Neef, Christoph; Meyer, Hans-Peter; Klingeler, Rüdiger

    2015-10-01

    Olivine structured LiCoPO4 was synthesized by a novel two-step process involving the hydrothermal synthesis of recently discovered metastable tetragonal LiCoPO4tetra and its transformation to the olivine-like phase. The transformation process does not change the size and shape of the particles so that they can be tailored by appropriate choice of the synthesis parameters and addition of organic compounds in the first production step. Our results demonstrate a clear effect of the particle shape on the electrochemical performance. The material shows discharge capacities up to 107 mAh/g for flower-like secondary particles synthesized under the mediation of citric acid. Electrochemical impedance spectroscopy reveals a strong surface reaction during the delithiation process which is key for the capacity fade of LiCoPO4 battery materials and a difference of three orders of magnitude in the diffusion coefficient of lithiated and delithiated species is observed.

  10. Design, synthesis, and structure-property relationships of isoindigo-based conjugated polymers.

    Science.gov (United States)

    Lei, Ting; Wang, Jie-Yu; Pei, Jian

    2014-04-15

    Conjugated polymers have developed rapidly due to their promising applications in low-cost, lightweight, and flexible electronics. The development of the third-generation donor-acceptor (D-A) polymers greatly improved the device performance in organic solar cells (OSCs) and field-effect transistors (FETs). However, for further improvement of device performance, scientists need to develop new building blocks, in particular electron-deficient aromatics, and gain an in-depth understanding of the structure-property relationships. Recently, isoindigo has been used as a new acceptor of D-A conjugated polymers. An isomer of indigo, isoindigo is a less well-known dye and can be isolated as a by-product from certain biological processes. It has two lactam rings and exhibits strong electron-withdrawing character. This electron deficiency gives isoindigo-based polymers intriguing properties, such as broad absorption and high open circuit voltage in OSCs, as well as high mobility and good ambient stability in FETs. In this Account, we review our recent progress on the design, synthesis, and structure-property relationship study of isoindigo-based polymers for FETs. Starting with some discussion on carrier transport in polymer films, we provide some basic strategies towards high-performance polymer FETs. We discuss the stability issue of devices, the impediment of the alkyl side chains, and the choice of the donor part of conjugated polymers. We demonstrate that introducing the isoindigo core effectively lowers the HOMO levels of polymers and provides FETs with long-time stability. In addition, we have found that when we use inappropriate alkyl side chains or non-centrosymmetric donors, the device performance of isoindigo polymers suffers. To further improve device performance and ambient stability, we propose several design strategies, such as using farther branched alkyl chains, modulating polymer energy levels, and extending π-conjugated backbones. We have found that using

  11. Synthesis and structure of nanomaterials in the system K2O-Nb2O5-SiO2

    Directory of Open Access Journals (Sweden)

    Georgi Chernev

    2009-06-01

    Full Text Available The aim of the present work is synthesis of ferroelectric nanomaterials, in the K2O-Nb2O5-SiO2 system via solgel method and studying the processes of formation and structure of the synthesized ferroelectric nanomaterials. The structure of synthesized materials has been studied by means of the following methods: EDS, XRD, FT-IR, SEM and AFM. The results obtained showed that the structure of the investigated compositions does not depend on the niobium content and all the samples keep their amorphous nature at room temperature. The surface structure shows random distribution of different kinds of aggregates with dimensions about 200–500 nm. The presence of a hybrid nanostructure with well-defi ned nanounits having special geometry is clearly observed.

  12. Study on the effects of complex ligands in the synthesis of TiO{sub 2} nanorod arrays using the sol-gel template method

    Energy Technology Data Exchange (ETDEWEB)

    Attar, A Sadeghzadeh; Mirdamadi, Sh [Department of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Ghamsari, M Sasani; Hajiesmaeilbaigi, F [Solid State Lasers Research Group, Laser and Optics Research School, Tehran 11365-8486 (Iran, Islamic Republic of); Katagiri, K; Koumoto, K [Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan)], E-mail: mirdamadi@iust.ac.ir

    2008-08-07

    This work reports the effects of complex ligands on the synthesis of TiO{sub 2} nanorod arrays prepared by the improved sol-gel template method. In this method, the obtained TiO{sub 2} sols from the sol-gel process were injected by a syringe into the templates and then the samples were immediately immersed into boiling TiO{sub 2}-sol solutions. Densely and directionally aligned anatase nanorods of about 80-130 nm diameter and a length of several micrometres were successfully fabricated using an optimal molar ratio of the TiO{sub 2} sol. The results show that the molar ratio of the TiO{sub 2} sol plays an important role in the morphology and structure of TiO{sub 2} nanorods. The reaction between titanium alkoxide and acetylacetone leads to the formation of complex compounds, which can prevent the precipitation of undesired phases from the highly reactive precursors. These complex ligands can be removed after annealing at various temperatures, which depend on the molar ratio of the TiO{sub 2} sol.

  13. Highly mismatched GaN1‑x Sb x alloys: synthesis, structure and electronic properties

    Science.gov (United States)

    Yu, K. M.; Sarney, W. L.; Novikov, S. V.; Segercrantz, N.; Ting, M.; Shaw, M.; Svensson, S. P.; Martin, R. W.; Walukiewicz, W.; Foxon, C. T.

    2016-08-01

    Highly mismatched alloys (HMAs) is a class of semiconductor alloys whose constituents are distinctly different in terms of size, ionicity and/or electronegativity. Electronic properties of the alloys deviate significantly from an interpolation scheme based on small deviations from the virtual crystal approximation. Most of the HMAs were only studied in a dilute composition limit. Recent advances in understanding of the semiconductor synthesis processes allowed growth of thin films of HMAs under non-equilibrium conditions. Thus reducing the growth temperature allowed synthesis of group III-N–V HMAs over almost the entire composition range. This paper focuses on the GaN x Sb1‑x HMA which has been suggested as a potential material for solar water dissociation devices. Here we review our recent work on the synthesis, structural and optical characterization of GaN1‑x Sb x HMA. Theoretical modeling studies on its electronic structure based on the band anticrossing (BAC) model are also reviewed. In particular we discuss the effects of growth temperature, Ga flux and Sb flux on the incorporation of Sb, film microstructure and optical properties of the alloys. Results obtained from two separate MBE growths are directly compared. Our work demonstrates that a large range of direct bandgap energies from 3.4 eV to below 1.0 eV can be achieved for this alloy grown at low temperature. We show that the electronic band structure of GaN1‑x Sb x HMA over the entire composition range is well described by a modified BAC model which includes the dependence of the host matrix band edges as well as the BAC model coupling parameters on composition. We emphasize that the modified BAC model of the electronic band structure developed for the full composition of GaN x Sb1‑x is general and is applicable to any HMA.

  14. Organosilane with gemini-type structure as the mesoporogen for synthesis of hierarchical porous ZSM-5 zeolite

    KAUST Repository

    Zhu, Haibo

    2016-02-08

    A new kind of organosilane (1,6-bis (diethyl(3-trimethoxysilylpropyl)ammonium) hexane bromide) with a gemini-type structure was prepared and used as a mesoporogen for the synthesis of hierarchical porous ZSM-5 zeolite. There are two quaternary ammonium centers along with double hydrolysable -RSi(OMe)3 fragments in the organosilane, which results in a strong interaction between this mesoporogen and silica-alumina gel. The organosilane can be easily incorporated into ZSM-5 zeolite structure during the crystallization process, and it was finally removed by calcination leading to secondary pores in ZSM-5. The synthesized ZSM-5 has been systematically studied by XRD, nitrogen adsorption, SEM, TEM, TG and solid-state one-dimensional (1D) and two-dimensional (2D) NMR, which reveals information on its detailed structure. It has a hierarchical porosity system, which combines the intrinsic micropores coming from the crystalline structure and irregular mesopores created by the organosilane template. Moreover, the mesoposity including pore size and volume within ZSM-5 can be systematically tuned by changing the organosilane/TEOS ratios, which confirms this organosilane has high flexibility of using as template for the synthesis of hierarchical porous zeolite.

  15. Nanometric solid solutions of the fluorite and perovskite type crystal structures: Synthesis and properties

    Directory of Open Access Journals (Sweden)

    Snežana Bošković

    2012-09-01

    Full Text Available In this paper a short review of our results on the synthesis of nanosized CeO2, CaMnO3 and BaCeO3 solid solutions are presented. The nanopowders were prepared by two innovative methods: self propagating room temperature synthesis (SPRT and modified glycine/nitrate procedure (MGNP. Different types of solid solutions with rare earth dopants in concentrations ranging from 0–0.25 mol% were synthesized. The reactions forming solid solutions were studied. In addition, the characteristics of prepared nanopowders, phenomena during sintering and the properties of sintered samples are discussed.

  16. Sterically demanding hetero-substituted [2]borametallocenophanes of group IV metals: synthesis, structure and reactivity.

    Science.gov (United States)

    Braunschweig, Holger; Dörfler, Rainer; Mies, Jan; Oechsner, Andreas

    2011-10-17

    We report the synthesis and characterisation of unprecedented unstrained [2]diborametallocenophanes of zirconium and hafnium that bear the bulky octamethylfluorenyl (η(5)-C(29)H(36)) system, the proligands of which were pre-constructed by a two-step synthesis. The compounds were fully characterised by NMR spectroscopy, MALDI-TOF mass spectrometry and X-ray diffraction analysis. Typical reactivities relevant to olefin polymerisation such as methylation and chloride abstraction were also investigated. Finally, a sterically demanding bis(octamethylfluorenyl) metallocene was prepared.

  17. One dimensional CuO nanocrystals synthesis by electrical explosion: A study on structural, optical and electronic properties

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan, Shutesh, E-mail: shutesh.k@onsemi.com [Department of Mechanical Engineering University of Malaya, 50603 Kuala Lumpur (Malaysia); ON Semiconductor Package Innovation and Development Center, 70450 Seremban (Malaysia); Haseeb, A.S.M.A.; Johan, Mohd Rafie [Department of Mechanical Engineering University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2014-02-15

    Highlights: • One-dimensional CuO nanoflakes were synthesized by novel wire explosion technique. • A physical synthesis method capable of producing high aspect ratio (1:16) nanocrystals. • Most energy efficient and eco-friendly synthesis of low-dimensional transition metal oxide nanocrystals. -- Abstract: One-dimensional (1D) copper oxide (CuO) nanocrystals were synthesized using a novel wire explosion in de-ionized (DI) water without any chemical additives. Highly crystalline 1D CuO nanocrystals with 1:16 aspect ratio were successfully synthesized using this technique. The chemical nature and physical structure of the nanocrystals were controlled by simply modulating the exploding medium temperature. The results showed that nanocrystals produced at explosion temperatures 65 °C and 95 °C are pure CuO with optical band-gap energy of 2.38 eV. High Resolution Transmission Electron Microscope analysis (HRTEM) indicates that the CuO nanocrystals are with growth in [1{sup ¯}11] and [1 1 1] directions. The epitaxial crystal growth kinetics of the 1D nanostructure by aggregation was discussed. The incorporation of microstructural features like edge dislocations and porosity in the growth mechanism was examined. X-ray photoelectron spectroscopy (XPS) characterization indicates the formation of high purity CuO nanocrystals with valence state +2. This study provides an energy efficient and eco-friendly synthesis method of 1D transition metal oxide nanocrystals for electronic applications.

  18. Synthesis of structurally diverse benzosuberene analogues and their biological evaluation as anti-cancer agents.

    Science.gov (United States)

    Tanpure, Rajendra P; George, Clinton S; Strecker, Tracy E; Devkota, Laxman; Tidmore, Justin K; Lin, Chen-Ming; Herdman, Christine A; Macdonough, Matthew T; Sriram, Madhavi; Chaplin, David J; Trawick, Mary Lynn; Pinney, Kevin G

    2013-12-15

    Diversely functionalized, fused aryl-alkyl ring systems hold a prominent position as well-established molecular frameworks for a variety of anti-cancer agents. The benzosuberene (6,7 fused, also referred to as dihydro-5H-benzo[7]annulene and benzocycloheptene) ring system has emerged as a valuable molecular core component for the development of inhibitors of tubulin assembly, which function as antiproliferative anti-cancer agents and, in certain cases, as vascular disrupting agents (VDAs). Both a phenolic-based analogue (known as KGP18, compound 39) and its corresponding amine-based congener (referred to as KGP156, compound 45), which demonstrate strong inhibition of tubulin assembly (low micromolar range) and potent cytotoxicity (picomolar range for KGP18 and nanomolar range for KGP156) are noteworthy examples of such benzosuberene-based compounds. In order to extend the structure-activity relationship (SAR) knowledge base related to benzosuberene anti-cancer agents, a series of eleven analogues (including KGP18) were prepared in which the methoxylation pattern on the pendant aryl ring as well as functional group incorporation on the fused aryl ring were varied. The synthetic approach to these compounds featured a sequential Wittig olefination, reduction, Eaton's reagent-mediated cyclization strategy to achieve the core benzosuberone intermediate, and represented a higher-yielding synthesis of KGP18 (which we prepared previously through a ring-expansion strategy). Incorporation of a fluorine or chlorine atom at the 1-position of the fused aryl ring or replacement of one of the methoxy groups with hydrogen (on the pendant aryl ring of KGP18) led to benzosuberene analogues that were both strongly inhibitory against tubulin assembly (IC50 approximately 1.0 μM) and strongly cytotoxic against selected human cancer cell lines (for example, GI50=5.47 nM against NCI-H460 cells with fluoro-benzosuberene analogue 37). A water-soluble phosphate prodrug salt of KGP18

  19. Integration of molecular-layer-deposited aluminum alkoxide interlayers into inorganic nanolaminate barriers for encapsulation of organic electronics with improved stress resistance

    Energy Technology Data Exchange (ETDEWEB)

    Hossbach, Christoph, E-mail: christoph.hossbach@tu-dresden.de; Fischer, Dustin; Albert, Matthias; Bartha, Johann W. [Institute of Semiconductor and Microsystems Technology, Technische Universität Dresden, 01187 Dresden (Germany); Nehm, Frederik, E-mail: frederik.nehm@iapp.de; Klumbies, Hannes; Müller-Meskamp, Lars; Leo, Karl [Institut für Angewandte Photophysik, Technische Universität Dresden, 01062 Dresden (Germany); Singh, Aarti; Richter, Claudia; Schroeder, Uwe; Mikolajick, Thomas [Nanoelectronics Materials Laboratory NaMLab gGmbH, Nöthnitzer Str. 64, 01187 Dresden (Germany)

    2015-01-15

    Diffusion barrier stacks for the encapsulation of organic electronics made from inorganic nanolaminates of Al{sub 2}O{sub 3} and TiO{sub 2} with aluminum alkoxide interlayers have been deposited by atomic layer deposition (ALD) and molecular layer deposition (MLD). As a part of the MLD process development, the deposition of aluminum alkoxide with low a density of about 1.7 g/cm{sup 3} was verified. The ALD/MLD diffusion barrier stack is meant to be deposited either on a polymer film, creating a flexible barrier substrate, or on top of a device on glass, creating a thin-film encapsulation. In order to measure the water vapor transmission rate (WVTR) through the barrier, the device is replaced by a calcium layer acting as a water sensor in an electrical calcium test. For the barrier stack applied as thin-film encapsulation on glass substrates, high resolution scanning electron microscopy investigations indicate that the inorganic nanolaminates without MLD interlayers are brittle as they crack easily upon the stress induced by the corroding calcium below. The introduction of up to three MLD interlayers of 12 nm each into the 48 nm barrier film laminate successfully mitigates stress issues and prevents the barrier from cracking. Using the three MLD interlayer configurations on glass, WVTRs of as low as 10{sup −5} g/m{sup 2}/d are measured at 38 °C and 32% relative humidity. On polymer barrier substrates, the calcium is evaporated onto the barrier stack and encapsulated with a cavity glass. In this configuration, the corroding calcium has space for expansion and gas release without affecting the underlying barrier film. In consequence, a WVTR of about 3 × 10{sup −3} g/m{sup 2}/d is measured for all samples independently of the number of MLD interlayers. In conclusion, a stabilization and preservation of the ALD barrier film against mechanical stress is achieved by the introduction of MLD interlayers into the inorganic nanolaminate.

  20. Synthesis of a new group of aliphatic hydrazide derivatives and the correlations between their molecular structure and biological activity.

    Science.gov (United States)

    Kostecka, Małgorzata

    2012-01-01

    In view of the growing demand for new compounds showing biological activity against pathogenic microorganisms, such as pathogenic and phytopathogenic fungi, the objective of this study was to synthesize a new group of aliphatic and aromatic derivatives of hydrazide. In consequence of the reactions observed during synthesis, the resulting compounds retained their linear structure. Their structure and lipophilicity, measured by high-performance liquid chromatography (HPLC), were analyzed. Correlations were determined between the compounds' molecular parameters and biological activity against Fusarium solani and Fusarium oxysporum fungi. The investigated compounds were also examined for their antifungal activity against Aspergillus fumigatus. The obtained results indicate that compounds with fluorine-containing substituents penetrate the cell structure more effectively and are characterized by higher antifungal potential than analogues with different substituents. PMID:22441334

  1. Synthesis of a New Group of Aliphatic Hydrazide Derivatives and the Correlations between Their Molecular Structure and Biological Activity

    Directory of Open Access Journals (Sweden)

    Małgorzata Kostecka

    2012-03-01

    Full Text Available In view of the growing demand for new compounds showing biological activity against pathogenic microorganisms, such as pathogenic and phytopathogenic fungi, the objective of this study was to synthesize a new group of aliphatic and aromatic derivatives of hydrazide. In consequence of the reactions observed during synthesis, the resulting compounds retained their linear structure. Their structure and lipophilicity, measured by high-performance liquid chromatography (HPLC, were analyzed. Correlations were determined between the compounds’ molecular parameters and biological activity against Fusarium solani and Fusarium oxysporum fungi. The investigated compounds were also examined for their antifungal activity against Aspergillus fumigatus. The obtained results indicate that compounds with fluorine-containing substituents penetrate the cell structure more effectively and are characterized by higher antifungal potential than analogues with different substituents.

  2. Dimer formation upon deprotonation: synthesis and structure of a m-terphenyl substituted (R,S)-dilithium disiloxanolate disilanol.

    Science.gov (United States)

    Čas, Daniel; Hurkes, Natascha; Spirk, Stefan; Belaj, Ferdinand; Bruhn, Clemens; Rechberger, Gerald N; Pietschnig, Rudolf

    2015-07-28

    The synthesis and structural characterization of the first dilithium salt of a tetrahydroxydisiloxane, [DmpSi(OH)OLi]2O (6), is described (Dmp = 2,6-dimesitylphenyl). The solid state structure reveals the presence of a dimeric motif where two disiloxane units are linked by coordinating lithium atoms which differs from those found for the sodium and potassium analogs. The arrangement imposed by the cluster formation leads to diastereomeric silicon atoms exhibiting (R,S) configuration in the solid state. In addition, the intermediates of the reaction, monolithiated and dilithiated silanetriol could be identified by means of high-resolution mass spectrometry and the formation of 6 is discussed. Moreover, the fully protonated tetrahydroxydisiloxane, [DmpSi(OH)2]2O has been obtained as well and its solid state structures with varying hydrogen bond acceptors have been surveyed. PMID:26098855

  3. Synthesis and crystal structure of the quaternary compound AgFe{sub 2}GaTe{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, Gerzon E., E-mail: gerzon@ula.ve [Laboratorio de Cristalografía, Departamento de Química, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101 (Venezuela, Bolivarian Republic of); Quintero, Eugenio; Tovar, Rafael; Grima-Gallardo, Pedro; Quintero, Miguel [Centro de Estudio de Semiconductores, Departamento de Física, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101 (Venezuela, Bolivarian Republic of)

    2014-11-15

    Highlights: • New quaternary compound. • Synthesis from solid state reaction. • Crystal structure. • Rietveld refinement. - Abstract: The crystal structure of the quaternary compound AgFe{sub 2}GaTe{sub 4}, belonging to the system I–II{sub 2}–III–VI{sub 4}, was characterized by Rietveld refinement using X-ray powder diffraction data. The powder pattern was composed by 84.5% of the principal phase AgFe{sub 2}GaTe{sub 4} and 15.5% of the secondary phase FeTe. This material crystallizes with stannite structure in the tetragonal space group I-42m (N° 121), Z = 2, unit cell parameters a = 6.3409(2) Å, c = 12.0233(4) Å, V = 483.42(3) Å{sup 3}, and is isostructural with CuFe{sub 2}InSe{sub 4}.

  4. Controlled synthesis of multi-shelled transition metal oxide hollow structures through one-pot solution route

    Institute of Scientific and Technical Information of China (English)

    Xi Wang; Yi-Jun Yang; Ying Ma; Jian-Nian Yao

    2013-01-01

    As one type of promising candidates fot environmental and energy-related systems,multi-shelled transition metal oxide hollow structures (MS-TMOHSs) have drawn great scientific and technical interest in the past few years.This article highlights recent advances in one-pot solution synthesis of MS-TMOHSs.We begin it with an overview of synthetic strategies that have been exploited to achieve these peculiar structures.We then focus on one-pot solution approaches in the following four sections:i) soft templates directed growth; ii) Ostwald ripening; iii) controlled etching; and iv) gas bubble assisted growth.After giving a brief discussion on the unique properties and applications of these multi-shelled hollow structures,we conclude this review with the general challenges and the potential future directions of this exciting area of research.

  5. Synthesis of Framework Isomer MOFs Containing Zinc and 4-Tetrazolyl Benzenecarboxylic Acid via a Structure Directing Solvothermal Approach

    Directory of Open Access Journals (Sweden)

    Carlos Ordonez

    2015-04-01

    Full Text Available The solvothermal synthesis of framework isomers was carried out using the hybrid carboxylate and tetrazolate functional ligand, 4-tetrazolyl benzenecarboxylic acid (H2TBC, TBC = 4-tetrazolyl benzenecarboxylate and zinc. H2TBC was also synthesized with the solvothermal approach, and is referred herein as structure 1. Using single-crystal X-ray diffraction, we found that the tetrazolate groups of TBC show an unusual “opposite-on” coordination mode with zinc. Three previously characterized metal-organic frameworks (MOFs were obtained by systematically changing the solvents of the H2TBC-Zn reaction, (1 ZnTBC, 2, which has a non-porous structure; (2 Zn2(TBC2(H2O, 3, which has an amphiphilic pore structure and (3 Zn2(TBC2{guest}, 4, which is porous and has channels containing uncoordinated N heteroatoms. Fluorescence spectra of 4 reveal a strong blue emission mainly from the TBC ligands.

  6. Autonomy-subnet based structural synthesis and liveness guarantying policy of Petri net model of flexible manufacturing system

    Institute of Scientific and Technical Information of China (English)

    XUE Lei; HAO Yue

    2004-01-01

    In this paper, an autonomous subnet based structural methodology for bottom-up synthesis of Petri Nets for Flexible Manufacturing Systems is proposed. Furthermore, the theoretical analysis of the model constructed by the method is carried by intensively using model's structural information, such as invariants, siphons, etc.. As a result, the analysis leads us to draw the general conclusion that the model obtained is conservativeness and thus bound, and characterize its liveness in terms of zero-marking minimal siphons. It is based on model's structural information that distinguishes our method from others. In line of this thought, a liveness guarantying policy for the obtained model is proposed. Some control subnets are merged into the original model according to the proposed synthesis rules in this paper to ensure that no minimal siphons are emptied in any state, therefore the liveness is guaranteed. As a result, a live, conservative and revertible Petri Nets is obtained. A practical example is also presented to demonstrate the effectiveness of this method.

  7. The effect of CNTs on structures and catalytic properties of AuPd clusters for H2O2 synthesis.

    Science.gov (United States)

    Yang, Hua-feng; Xie, Peng-yang; Yu, Hui-you; Li, Xiao-nian; Wang, Jian-guo

    2012-12-28

    The structures and catalytic properties of AuPd clusters supported on carbon nanotubes (CNTs) for H(2)O(2) synthesis have been investigated by means of density functional theory calculations. Firstly, the structures of AuPd clusters are strongly influenced by CNTs, in which the bottom layers are mainly composed of Pd and the top layers are a mix of Au and Pd due to the stronger binding of Pd than Au on CNTs. Especially, it is found that O(2) adsorption on the Pd/CNTs interfacial sites is much weaker than that on the only Pd sites, which is in contrast to transition metal oxide (for example TiO(2), Al(2)O(3), CeO(2)) supported metal clusters. Furthermore, Pd ensembles on the interfacial sites have far superior catalytic properties for H(2)O(2) formation than those away from CNT supports due to the changes in electronic structures caused by the CNTs. Therefore, our study provides a physical insight into the enhanced role of carbon supports in H(2)O(2) synthesis over supported AuPd catalysts. PMID:23032860

  8. Synthesis, characterization, crystal structures, and antibacterial activity of some new 1-(3,4,5-trimethoxybenzoyl)-3-aryl thioureasreas

    OpenAIRE

    Saeed, Aamer; Khera, Rasheed Ahmad; Abbas, Naeem; Latif, Muhammad

    2010-01-01

    Synthesis of some novel 1-(3,4,5-trimethoxy)benzoyl-3- arylthiourea derivatives (1a-o) was accomplished in 2 steps. The synthetic route involves the reaction of 1-(3,4,5-trimethoxy)benzoyl chloride with potassium thiocyanate in 1:1 molar ratio in acetone to afford the corresponding isothiocyante followed by treatment with suitably substituted anilines. The structures of the products were established by elemental analyses, IR, 1H- and 13C-NMR, and mass spectroscopy and for 1b and 1m f...

  9. Synthesis of reactive nucleic acid analogues and their application for the study of structure and functions of biopolymers

    Energy Technology Data Exchange (ETDEWEB)

    Kanevskii, Igor' E; Kuznetsova, Svetlana A [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    1998-07-31

    Data on the synthesis of reactive derivatives of nucleic acid analogues and their application for the study of structure and functions of biopolymers are generalised. The main types of such analogues including photoactivated reagents containing azidoaryl, halogeno, and thiol groups, psoralen and its derivatives, platinum-based reagents, and nucleic acid analogues containing substituted pyrophosphate or acyl phosphate internucleotide groups are presented. The mechanisms of interaction of these compounds with proteins and nucleic acids are considered. The prospects for the in vivo application of reactive nucleic acids in various systems are discussed. The bibliography includes 76 references.

  10. Structure and models of artifactual routine design problems for computational synthesis

    NARCIS (Netherlands)

    Jauregui Becker, J.M.; Tragter, H.; Houten, van F.J.A.M.

    2009-01-01

    Computational synthesis (CS) researches the automatic generation of solutions to design problems. The aim is to shorten design times and present the user with multiple design solutions. However, initializing a new CS process has not received much attention in literature. With this motivation, this p

  11. Inhibition of RNA synthesis in vitro by acridines--relation between structure and activity.

    Science.gov (United States)

    Piestrzeniewicz, M K; Wilmańska, D; Studzian, K; Szemraj, J; Czyz, M; Denny, W A; Gniazdowski, M

    1998-01-01

    The effects of acridine derivatives (proflavine and 2,7-dialkyl derivatives, diacridines and triacridines, 9-aminoacridine carboxamides, and 9-anilinoacridine, amsacrine and its congeners) on overall RNA synthesis in vitro, on synthesis of initiating oligonucleotides and the binding of the enzyme to DNA were studied. The primary mechanism of action is related to inhibition of the enzyme binding to DNA. The acridines (intercalating or non-intercalating and bis-intercalating ligands) assayed here differ in the properties of their complexes with DNA. Correlation is generally observed between inhibition of RNA synthesis in vitro and cytotoxicity in cell cultures for di- and triacridines and 9-aminoacridine carboxamide derivatives. No relationship was found between the effect on RNA polymerase system and biological effects for amsacrine and its derivatives in contrast to the other series of acridines studied here. The aniline ring seems to decrease the inhibitory potency of a ligand. The discrepancy between the biological effect and RNA synthesis inhibition may be due to a different mechanism of cytotoxicity action of amsacrine which is a potent topoisomerase II poison. PMID:9679327

  12. Amitorines A and B, Nitrogenous Diterpene Metabolites of Theonella swinhoei: Isolation, Structure Elucidation, and Asymmetric Synthesis.

    Science.gov (United States)

    Ota, Koichiro; Hamamoto, Yukiko; Eda, Wakiko; Tamura, Kenta; Sawada, Akiyoshi; Hoshino, Ayako; Mitome, Hidemichi; Kamaike, Kazuo; Miyaoka, Hiroaki

    2016-04-22

    Two new nitrogenous prenylbisabolanes never before found in Lithistid sponges have been isolated from Theonella swinhoei. These new diterpenes, named amitorine A (1) and amitorine B (2), containing a prenylbisabolane skeleton have been characterized by spectroscopic analyses, and the relative and absolute configurations of 1 and 2 were determined by asymmetric synthesis of both diastereomers via the common bicyclic lactone 6 intermediate.

  13. Synthesis, Structure, and Reactivity ofbis(1,2,4-tri-t-butylcyclopentadienyl) Complexes of Cerium

    Energy Technology Data Exchange (ETDEWEB)

    Werkema, Evan L.

    2005-05-19

    The sterically demanding 1,2,4-tri-t-butylcyclopentadienylligand (1,2,4-(Me3C)3C5H2, hereafter Cp') has been used to preparemonomeric cerium metallocenes, Cp 2CeX (X = Cl, I, OSO2CF3), which areused to synthesize the benzyl, Cp'2CeCH2C6H5. The benzyl is a usefulstarting material for preparing other complexes in the Cp'2CeZ system (Z= BF4, F, NH2, C6H5, H). X-ray crystal structures of Cp'2CeOSO2CF3,Cp'2CeF, Cp'2CeCH2C6H5, and Cp'2CeH are presented. The benzyl slowlydecomposes in solution to toluene and a metallacycle,[Cp'][(Me3C)2C5H2(CMe2CH2)]Ce. The ring CMe3 groups of both themetallacycle and the hydride, Cp'2CeH, can be fully deuterated byprolonged exposure to C6D6, providing a useful labeling tool inmechanistic studies.The hydride activates C-F and/or C-H bonds influorobenzenes, C6HxF6-x , x = 0-5. The reactions are selective, with theselectivity depending on the presence of two fluorines ortho to thereaction site more than on the type of bond activated. Complexes of thetype Cp'2CeC6HxF5-x , x = 0-4, are formed as intermediates, which slowlydecompose in solution to Cp'2CeF and fluorobenzynes, C6HxF4-x, x = 0-4,which are trapped. The rate at which Cp'2CeC6HxF5-x complexes decomposeincreases as the number of fluorines decreases. Complexes with oneortho-fluorine decompose much faster than those with two ortho-fluorines.The metallacycle activates only C-H bonds in fluorobenzenes, permittingthe synthesis of specific Cp'2CeC6HxF5-x complexes. The crystal structureof Cp'2CeC6F5 is presented. The hydride and the metallacycle react withfluoromethanes, CH4-xFx, x = 1-3, through postulated Cp'2CeCH3-xFxintermediates to generate Cp'2CeF and other products. The other products,CH4, tri-t-butylbenzenes, tri-t-butylfluorobenzenes, and a presumedmetallocene cerium fluoride with one Cp' and one (Me2EtC)(Me3C)2C5H2ligand, suggest a decomposition pathway for Cp'2CeCH3-xFx , x = 1

  14. Thermal Stability of Neodymium Aluminates High-κ Dielectric Deposited by Liquid Injection MOCVD Using Single-Source Heterometallic Alkoxide Precursors

    Directory of Open Access Journals (Sweden)

    P. Taechakumput

    2012-01-01

    Full Text Available Thin films of neodymium aluminate (NdAlOx have been deposited by liquid injection metalorganic chemical vapor deposition (MOCVD using the bimetallic alkoxide precursor [NdAl(OPri6(PriOH]2. The effects of high-temperature postdeposition annealing on NdAlOx thin films are reported. The as-deposited thin films are amorphous in nature. X-ray diffraction (XRD and medium energy ion scattering (MEIS show, respectively, no crystallization or interdiffusion of metal ions into the substrate after annealing at 950°C. The capacitance-voltage (C-V and current-voltage (I-V characteristics of the thin films exhibited good electrical integrity following annealing. The dielectric permittivity (κ of the annealed NdAlOx was 12, and a density of interface states at flatband (Dit of 4.01×1011  cm−2 eV−1 was measured. The deposited NdAlOx thin films are shown to be able to endure high-temperature stress and capable of maintaining excellent dielectric properties.

  15. Synthesis of Carbon nano structures by plasma discharge; Sintesis de nanoestructuras de carbono por descarga de plasmaa

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez L, M.L

    2007-07-01

    Due to the great quantity of applications of the carbon nano structures (NEC) in diverse areas like: synthesis of super-resistant materials, hydrogen storage, nano sensors generation and nano catalysts, it has seen the necessity to generate new processes of synthesis of this materials as well as to already improve those existent. The present work has as objective to optimize the NEC synthesis process by means of the electric arc method which uses alternating current to high frequencies (HF), obtaining relatively clean products; that is to say, it hardly presents amorphous material neither sludges. They stand out the obtaining of carbon nano fibers (NFC) by means of a luminescent-arch discharge, in a gas mixture of He-CH{sub 4} with 34% at. Ni/10.32% at.Y like catalyst; at a frequency of 42 kHz and low power (300 W). This method benefits the amass of the particles in both electrodes due to the high frequencies. The time of duration of the process oscillates between 5 and 20 minutes. The obtained product was characterized by scanning electron microscopy (MEB), transmission electron microscopy (MET) to determine the NEC type obtained and by X-ray diffraction analysis and Raman spectroscopy for determining the purity of the samples. The NFC is relatively free of amorphous coal. The surface and structural analysis indicates that the fibers have a half diameter of 80 nm. It is also made, a study by optical emission spectroscopy of plasma using the Swan band for determining the temperature. (Author)

  16. Quick synthesis of highly aligned or randomly oriented nanofibrous structures composed of C60 molecules via self-assembly

    Science.gov (United States)

    Kurosu, Shunji; Fukuda, Takahiro; Maekawa, Toru

    2013-06-01

    Assemblies, which are composed of nanoparticles such as nanofibres, have been intensively studied in recent years. This has particularly been the case in the field of biomedicine, where the aim is to develop efficient methodologies for capturing and separating target biomolecules and cells and/or encouraging bio-chemical reactions, utilizing the extremely high surface area to volume ratio of assemblies. There is an urgent need for the development of a quick synthesis method of forming nanofibrous structures on the surface of biomedical microchips and devices for the investigation of the interactions between biomolecules/cells and the nanostructures. Here, we produce nanofibrous structures composed of C60 molecules, which are aligned in one direction or randomly oriented, by dissolving C60 molecules and sulphur in benzene and evaporating a droplet of the solution on a glass substrate under appropriate conditions. The synthesis time is as short as 30 s. Sulphur is extracted and nanofibres are crystallized by leaving them in supercritical carbon dioxide.

  17. Structured superparamagnetic nanoparticles for high performance mediator of magnetic fluid hyperthermia: synthesis, colloidal stability and biocompatibility evaluation.

    Science.gov (United States)

    Thorat, N D; Otari, S V; Bohara, R A; Yadav, H M; Khot, V M; Salunkhe, A B; Phadatare, M R; Prasad, A I; Ningthoujam, R S; Pawar, S H

    2014-09-01

    Core-shell structures with magnetic core and metal/polymer shell provide a new opportunity for constructing highly efficient mediator for magnetic fluid hyperthermia. Herein, a facile method is described for the synthesis of superparamagnetic LSMO@Pluronic F127 core-shell nanoparticles. Initially, the surface of the LSMO nanoparticles is functionalized with oleic acid and the polymeric shell formation is achieved through hydrophobic interactions with oleic acid. Each step is optimized to get good dispersion and less aggregation. This methodology results into core-shell formation, of average diameter less than 40 nm, which was stable under physiological conditions. After making a core-shell formulation, a significant increase of specific absorption rate (up to 300%) has been achieved with variation of the magnetization (Fe3O4. MTT assay is used to evaluate the toxicity of bare and core-shell MNPs. The mechanism of cell death by necrosis and apoptosis is studied with sequential staining of acridine orange and ethidium bromide using fluorescence and confocal microscopy. The present work reports a facile method for the synthesis of core-shell structure which significantly improves SAR and biocompatibility of bare LSMO MNPs, indicating potential application for hyperthermia. PMID:25063164

  18. Synthesis of Nanoscale TiO2 and Study of the Effect of Their Crystal Structure on Single Cell Response

    Directory of Open Access Journals (Sweden)

    Z. R. Ismagilov

    2012-01-01

    Full Text Available To study the effect of nanoscale titanium dioxide (TiO2 on cell responses, we synthesized four modifications of the TiO2 (amorphous, anatase, brookite, and rutile capable of keeping their physicochemical characteristics in a cell culture medium. The modifications of nanoscale TiO2 were obtained by hydrolysis of TiCl4 and Ti(i-OC3H74 (TIP upon variation of the synthesis conditions; their textural, morphological, structural, and dispersion characteristics were examined by a set of physicochemical methods: XRD, BET, SAXS, DLS, AFM, SEM, and HR-TEM. The effect of synthesis conditions (nature of precursor, pH, temperature, and addition of a complexing agent on the structural-dispersion properties of TiO2 nanoparticles was studied. The hydrolysis methods providing the preparation of amorphous, anatase, brookite, and rutile modifications of TiO2 nanoparticles 3–5 nm in size were selected. Examination of different forms of TiO2 nanoparticles interaction with MDCK cells by transmission electron microscopy of ultrathin sections revealed different cell responses after treatment with different crystalline modifications and amorphous form of TiO2. The obtained results allowed us to conclude that direct contact of the nanoparticles with cell plasma membrane is the primary and critical step of their interaction and defines a subsequent response of the cell.

  19. The synthesis and structure of gemini QASs of 1,4:3,6-dianhydro-L-iditol

    Science.gov (United States)

    Sikora, Karol; Nowacki, Andrzej; Sikorski, Artur; Dmochowska, Barbara

    2015-12-01

    New, efficient, straightforward method of synthesizing quaternary diammonium salts of 1,4:3,6-dianhydro-L-iditol have been developed. This paper presents the synthesis and structural analysis of diammonium (gemini) salts, including their X-ray diffraction analysis, wherein the linking structure of nitrogen atoms consists of two fused furanoid rings. 1,4:3,6-dianhydro-2,5-di-O-triflyl-D-mannitol and four tertiary amines, i.e., 4-(N,N-dimethylamino)pyridine (DMAP), pyridine, trimethylamine and N,N-dimethyloctylamine, were used for the synthesis. All the syntheses were carried out under mild conditions by the direct nucleophilic displacement of the O-triflil group by the amine. Walden inversion of configuration at C2 and C5 atoms has occurred during the reaction, giving products with L-ido configuration. Furthermore, NMR and X-ray conformational analysis of 1,4:3,6-dianhydrohexitol residue was done. In most cases furanoid rings adopt the twisted conformation both in the crystal and in solution.

  20. Combustion synthesis and structural analysis of nanocrystalline nickel ferrite at low temperature regime

    International Nuclear Information System (INIS)

    Combustion synthesis of single phase Nickel ferrite was successfully achieved at low temperature regime. The obtained powders were calcinated to increase the crystallinity and their characterization change due to calcinations is investigated in detail. Citric acid used as a chelating agent for the synthesis of nickel ferrite. Pure single phase nickel ferrites were found at this low temperature. The average crystalline sizes were measured by using powder XRD measurements. Surface morphology was investigated through Transmission Electron Microscope (TEM). Particle size calculated in XRD is compared with TEM results. Magnetic behaviour of the samples is analyzed by using Vibrating Sample Magnetometer (VSM). Saturation magnetization, coercivity and retentivity are measured and their results are discussed in detail