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Sample records for complexes structural characterization

  1. Structure-based characterization of multiprotein complexes.

    Science.gov (United States)

    Wiederstein, Markus; Gruber, Markus; Frank, Karl; Melo, Francisco; Sippl, Manfred J

    2014-07-08

    Multiprotein complexes govern virtually all cellular processes. Their 3D structures provide important clues to their biological roles, especially through structural correlations among protein molecules and complexes. The detection of such correlations generally requires comprehensive searches in databases of known protein structures by means of appropriate structure-matching techniques. Here, we present a high-speed structure search engine capable of instantly matching large protein oligomers against the complete and up-to-date database of biologically functional assemblies of protein molecules. We use this tool to reveal unseen structural correlations on the level of protein quaternary structure and demonstrate its general usefulness for efficiently exploring complex structural relationships among known protein assemblies. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  2. A structurally characterized organometallic plutonium(IV) complex

    Energy Technology Data Exchange (ETDEWEB)

    Apostolidis, Christos; Walter, Olaf [European Commission, Joint Research Centre, Directorate G - Nuclear Safety and Security, Karlsruhe (Germany); Vogt, Jochen; Liebing, Phil; Edelmann, Frank T. [Chemisches Institut, Otto-von-Guericke-Universitaet Magdeburg (Germany); Maron, Laurent [Laboratoire de Physique et Chimie des Nanoobjets (LPCNO), Universite de Toulouse/INSA/CNRS (UMR5215), Toulouse (France)

    2017-04-24

    The blood-red plutonocene complex Pu(1,3-COT'')(1,4-COT'') (4; COT''=η{sup 8}-bis(trimethylsilyl)cyclooctatetraenyl) has been synthesized by oxidation of the anionic sandwich complex Li[Pu(1,4-COT''){sub 2}] (3) with anhydrous cobalt(II) chloride. The first crystal structure determination of an organoplutonium(IV) complex revealed an asymmetric sandwich structure for 4 where one COT'' ring is 1,3-substituted while the other retains the original 1,4-substitution pattern. The electronic structure of 4 has been elucidated by a computational study, revealing a probable cause for the unexpected silyl group migration. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Structural characterization of polymorphs and molecular complexes of finasteride

    Science.gov (United States)

    Wawrzycka, Irena; Stȩpniak, Krystyna; Matyjaszczyk, Sławomir; Kozioł, Anna E.; Lis, Tadeusz; Abboud, Khalil A.

    1999-01-01

    The molecular structure of finasteride, 17 β-( N-tert-butylcarbamoyl)-4-aza-5 α-androst-1-en-3-one, and structures of three related crystalline forms have been determined by X-ray analysis. The rigid steroid skeleton of the molecule adopts a half-chair/chair/chair/half-chair conformation. Two peptide groups, one cyclic (lactam) in the ring A and a second being a part of the substituent at C17, are the main factors influencing intermolecular contacts. Different hydrogen-bond interactions of these hydrophilic groups are observed in the crystal structures. An infinite ribbon of finasteride molecules is formed between lactam groups in the orthorhombic homomolecular crystal ( 1) obtained from an ethanol solution. The linear molecular complex finasteride-acetic acid ( 1a) is connected by hydrogen bonds between the lactam of finasteride and the carboxyl group of acetic acid. The crystallization from an ethyl acetate solution gives a complex structure of bis-finasteride monohydrate ethyl acetate clathrate ( 1b) with guest molecule disordered in channels. Crystals of a second (monoclinic) finasteride polymorph ( 2) were obtained during thermal decomposition of 1a, and sublimation of 1, 1a and 1b. Two polymorphic forms show different IR spectra.

  4. Cryo-Electron Tomography for Structural Characterization of Macromolecular Complexes

    Science.gov (United States)

    Cope, Julia; Heumann, John; Hoenger, Andreas

    2011-01-01

    Cryo-electron tomography (cryo-ET) is an emerging 3-D reconstruction technology that combines the principles of tomographic 3-D reconstruction with the unmatched structural preservation of biological material embedded in vitreous ice. Cryo-ET is particularly suited to investigating cell-biological samples and large macromolecular structures that are too polymorphic to be reconstructed by classical averaging-based 3-D reconstruction procedures. This unit aims to make cryo-ET accessible to newcomers and discusses the specialized equipment required, as well as the relevant advantages and hurdles associated with sample preparation by vitrification and cryo-ET. Protocols describe specimen preparation, data recording and 3-D data reconstruction for cryo-ET, with a special focus on macromolecular complexes. A step-by-step procedure for specimen vitrification by plunge freezing is provided, followed by the general practicalities of tilt-series acquisition for cryo-ET, including advice on how to select an area appropriate for acquiring a tilt series. A brief introduction to the underlying computational reconstruction principles applied in tomography is described, along with instructions for reconstructing a tomogram from cryo-tilt series data. Finally, a method is detailed for extracting small subvolumes containing identical macromolecular structures from tomograms for alignment and averaging as a means to increase the signal-to-noise ratio and eliminate missing wedge effects inherent in tomographic reconstructions. PMID:21842467

  5. Structural characterization of core-bradavidin in complex with biotin

    Science.gov (United States)

    Agrawal, Nitin; Määttä, Juha A. E.; Kulomaa, Markku S.; Hytönen, Vesa P.; Johnson, Mark S.; Airenne, Tomi T.

    2017-01-01

    Bradavidin is a tetrameric biotin-binding protein similar to chicken avidin and bacterial streptavidin, and was originally cloned from the nitrogen-fixing bacteria Bradyrhizobium diazoefficiens. We have previously reported the crystal structure of the full-length, wild-type (wt) bradavidin with 138 amino acids, where the C-terminal residues Gly129-Lys138 (“Brad-tag”) act as an intrinsic ligand (i.e. Gly129-Lys138 bind into the biotin-binding site of an adjacent subunit within the same tetramer) and has potential as an affinity tag for biotechnological purposes. Here, the X-ray structure of core-bradavidin lacking the C-terminal residues Gly114-Lys138, and hence missing the Brad-tag, was crystallized in complex with biotin at 1.60 Å resolution [PDB:4BBO]. We also report a homology model of rhodavidin, an avidin-like protein from Rhodopseudomonas palustris, and of an avidin-like protein from Bradyrhizobium sp. Ai1a-2, both of which have the Brad-tag sequence at their C-terminus. Moreover, core-bradavidin V1, an engineered variant of the original core-bradavidin, was also expressed at high levels in E. coli, as well as a double mutant (Cys39Ala and Cys69Ala) of core-bradavidin (CC mutant). Our data help us to further engineer the core-bradavidin–Brad-tag pair for biotechnological assays and chemical biology applications, and provide deeper insight into the biotin-binding mode of bradavidin. PMID:28426764

  6. Structural characterization of core-bradavidin in complex with biotin.

    Directory of Open Access Journals (Sweden)

    Nitin Agrawal

    Full Text Available Bradavidin is a tetrameric biotin-binding protein similar to chicken avidin and bacterial streptavidin, and was originally cloned from the nitrogen-fixing bacteria Bradyrhizobium diazoefficiens. We have previously reported the crystal structure of the full-length, wild-type (wt bradavidin with 138 amino acids, where the C-terminal residues Gly129-Lys138 ("Brad-tag" act as an intrinsic ligand (i.e. Gly129-Lys138 bind into the biotin-binding site of an adjacent subunit within the same tetramer and has potential as an affinity tag for biotechnological purposes. Here, the X-ray structure of core-bradavidin lacking the C-terminal residues Gly114-Lys138, and hence missing the Brad-tag, was crystallized in complex with biotin at 1.60 Å resolution [PDB:4BBO]. We also report a homology model of rhodavidin, an avidin-like protein from Rhodopseudomonas palustris, and of an avidin-like protein from Bradyrhizobium sp. Ai1a-2, both of which have the Brad-tag sequence at their C-terminus. Moreover, core-bradavidin V1, an engineered variant of the original core-bradavidin, was also expressed at high levels in E. coli, as well as a double mutant (Cys39Ala and Cys69Ala of core-bradavidin (CC mutant. Our data help us to further engineer the core-bradavidin-Brad-tag pair for biotechnological assays and chemical biology applications, and provide deeper insight into the biotin-binding mode of bradavidin.

  7. Structural characterization of core-bradavidin in complex with biotin.

    Science.gov (United States)

    Agrawal, Nitin; Määttä, Juha A E; Kulomaa, Markku S; Hytönen, Vesa P; Johnson, Mark S; Airenne, Tomi T

    2017-01-01

    Bradavidin is a tetrameric biotin-binding protein similar to chicken avidin and bacterial streptavidin, and was originally cloned from the nitrogen-fixing bacteria Bradyrhizobium diazoefficiens. We have previously reported the crystal structure of the full-length, wild-type (wt) bradavidin with 138 amino acids, where the C-terminal residues Gly129-Lys138 ("Brad-tag") act as an intrinsic ligand (i.e. Gly129-Lys138 bind into the biotin-binding site of an adjacent subunit within the same tetramer) and has potential as an affinity tag for biotechnological purposes. Here, the X-ray structure of core-bradavidin lacking the C-terminal residues Gly114-Lys138, and hence missing the Brad-tag, was crystallized in complex with biotin at 1.60 Å resolution [PDB:4BBO]. We also report a homology model of rhodavidin, an avidin-like protein from Rhodopseudomonas palustris, and of an avidin-like protein from Bradyrhizobium sp. Ai1a-2, both of which have the Brad-tag sequence at their C-terminus. Moreover, core-bradavidin V1, an engineered variant of the original core-bradavidin, was also expressed at high levels in E. coli, as well as a double mutant (Cys39Ala and Cys69Ala) of core-bradavidin (CC mutant). Our data help us to further engineer the core-bradavidin-Brad-tag pair for biotechnological assays and chemical biology applications, and provide deeper insight into the biotin-binding mode of bradavidin.

  8. Synthesis and structural characterization of scandium SALEN complexes.

    Science.gov (United States)

    Meermann, Christian; Sirsch, Peter; Törnroos, Karl W; Anwander, Reiner

    2006-02-28

    A series of heteroleptic scandium SALEN complexes, [(SALEN)Sc(mu-Cl)]2 and (SALEN)Sc[N(SiHMe2)2] is obtained via amine elimination reactions using [Sc(N(i)Pr2)2(mu-Cl)(THF)]2 and Sc[N(SiHMe2)2]3(THF) as metal precursors, respectively. H(2)SALEN ligand precursors comprising H2Salen [(1,2-ethandiyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol], H2Salpren [(2,2-dimethylpropanediyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol], H2Salcyc [(1R,2R)-(-)-1,2-cyclohexanediyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol] and H2Salphen [((1S,2S)-(-)-1,2-diphenylethandiyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol] are selected according to solubility and ligand backbone variation ("=N-(R)-N=" bite angle) criteria. Consideration is given to the feasibility of [Cl --> NR2] and [N(SiHMe2)2--> OSiR3] secondary ligand exchange reactions. X-ray crystal structure analyses of donor-free (Salpren)Sc(N(i)Pr2), (R,R)-(Salcyc)Sc[N(SiHMe2)2], (Salen)Sc(OSi(t)BuPh2) and (Salphen)Sc(OSiH(t)Bu2) reveal (i) a very short Sc-N bond distance of 2.000(3) A, (ii) weak beta(Si-H)(amido)-Sc agostic interactions and (iii) an exclusive intramolecularly tetradentate and intrinsically bent coordination mode of the SALEN ligands with angle(Ph,Ph) dihedral angles and Sc-[N(2)O(2)] distances in the 124.27(9)-127.7(3) degrees and 0.638(1)-0.688(1) A range, respectively.

  9. Structural characterization of inclusion complex of arbutin and ...

    African Journals Online (AJOL)

    cyclodextrin. Yun Li, Fang Li, Hongyan Cai, Xuan Chen, Wei Sun, Wangyang Shen. Abstract. Purpose: To improve the solubility and stability of arbutin and to expand its application by preparing its inclusion complex with hydroxypropyl-β- ...

  10. Structural characterization of inclusion complex of arbutin and ...

    African Journals Online (AJOL)

    and browning reactions [19,20]. The most common CDs used as formulation vehicles are α-, β- and γ-CDs containing six, seven and eight glucopyranose units .... them, such as hydrogen bonds or van der Waals force [24]. The decomposition temperature of the complex was about 300 °C, indicating that the heat stability of ...

  11. Synthesis, characterization, and structure of reduced tungsten chalcogenide cluster complexes

    Energy Technology Data Exchange (ETDEWEB)

    Xiaobing, Xie [Iowa State Univ., Ames, IA (United States)

    1997-10-17

    Over the previous twenty years, ternary molybdenum chalcogenides of the general formula MxMo6Y8 (M = ternary metal cation; Y = chalcogenide), known as Chevrel phases, have been extensively studied. Many of these compounds have been found to have superconductivity, catalytic activity and ionic conductivity. The rich chemistry of the Chevrel phases raises considerable interest in finding the tungsten analogues of these phases. However, no such analogue has ever been synthesized, although the Chevrel phases are usually prepared directly from elements at high temperatures above 1000{degrees}C. The absence of the tungsten analogues may be caused by their thermodynamic instability at such high temperatures. Thus it might be necessary to avoid high-temperature synthetic procedures in order to establish the ternary and binary tungsten chalcogenides. A major focus of the McCarley research group has been on the preparation of M6Y8L6 (M = Mo, W; Y = S, Se, Te) cluster complexes as low temperature pathways to the Chevrel phases.

  12. First structurally characterized mixed-halogen nickel(III) NCN-pincer complex.

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    Kozhanov, Konstantin A; Bubnov, Michael P; Cherkasov, Vladimir K; Fukin, Georgy K; Vavilina, Nina N; Efremova, Larisa Yu; Abakumov, Gleb A

    2009-03-01

    A square-pyramidal mixed-halogen nickel(III) NCN-pincer complex (PipeNCN)NiClBr (where PipeNCN=2,6-bis(piperidinomethyl)phenyl) was structurally characterized. Bromine occupies apical position; pincer ligand and chlorine atom are in the basal plane. EPR detects that complex in solution exists as a mixture of two structural isomers with bromine or chlorine atoms in the top of pyramid.

  13. Characterization of the membrane-coating Nup84 complex: paradigm for the nuclear pore complex structure.

    Science.gov (United States)

    Debler, Erik W; Hsia, Kuo-Chiang; Nagy, Vivien; Seo, Hyuk-Soo; Hoelz, André

    2010-01-01

    Nuclear pore complexes (NPCs) function as selective gates for nucleocytoplasmic transport. Although the NPC was discovered more than half a century ago, our knowledge of NPC components in atomic detail has exploded only over the past few years. Recent structural, biochemical, and in vivo studies of NPC components, in particular the membrane-coating heptameric Nup84 complex, have shed light onto the NPC architecture as well as onto its dynamic nature. Striking similarities were revealed between the components of the NPC and of coat protein complexes in the endocytic and secretory pathways, supporting their common evolutionary origin in a progenitor protocoatomer. Here, we summarize these findings and discuss emerging concepts that underlie the molecular architecture and the dynamics of the NPC. We conclude that the uncovered principles are not limited to the NPC, but are likely to extend to other macromolecular assemblies.

  14. Novel polymeric potassium complex: Its synthesis, structural characterization, photoluminescence and electrochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Ceyhan, Goekhan [Chemistry Department, K.Maras Suetcue Imam University, 46100 K.Maras (Turkey); Tuemer, Mehmet, E-mail: mtumer@ksu.edu.tr [Chemistry Department, K.Maras Suetcue Imam University, 46100 K.Maras (Turkey); Koese, Muhammet; McKee, Vickie [Chemistry Department, Loughborough University, LE11 3TU Leicestershire (United Kingdom)

    2012-03-15

    In this paper, we obtained a novel poly(vanillinato potassium) complex (PVP) as a single crystal and characterized by analytical and spectroscopic methods. A single crystal of the PVP was obtained from the acetone solution. X-ray structural data show that crystals contain polymeric K{sup +} complex of vanillin. Each potassium ion in the polymeric structure is identical and seven-coordinate, bonded to two methoxy, two phenoxy and three aldehyde oxygen atoms from four vaniline molecules. Two aldehyde oxygen atoms are bridging between potassium ions. It crystallizes in the monoclinic system, space group P2{sub 1}/c, with lattice parameters a=9.6215(10) A, b=17.4139(19) A, c=9.6119(10) A, {beta}=100.457(2) Degree-Sign and Z=4. Thermal properties of the PVP were investigated by TGA, DTA and DSC methods. The electrochemical properties of the complex were studied in different solvents and at various scan rates. The luminescence properties of the complex in different solvents and at different pH values have been investigated. The results show that the complex exhibits more efficient luminescence property in CH{sub 3}CN and n-butanol. - Highlights: Black-Right-Pointing-Pointer Novel polymeric potassium complex was prepared and fully characterized. Black-Right-Pointing-Pointer X-ray crystal structure of complex was reported. Black-Right-Pointing-Pointer Electrochemical properties of compound were investigated. Black-Right-Pointing-Pointer Thermal and DSC measurements of complex were examined.

  15. Synthesis, characterization and crystal structures of oxovanadium(V complexes derived from similar aroylhydrazone ligands

    Directory of Open Access Journals (Sweden)

    X-Z Zhang

    2015-10-01

    Full Text Available Reaction of [VO(acac2] (acac = acetylacetonate with N’-(5-chloro-2-hydroxybenzylidene-3-methoxybenzohydrazide (H2L1 and N’-(2-hydroxy-4-methoxybenzylidene-4-nitrobenzohydrazide (H2L2 in methanol affords methanol-coordinated mononuclear oxovanadium(V complexes, [VOL1(OMe(MeOH] (1 and [VOL2(OMe(MeOH] (2, respectively. The complexes were characterized by elemental analysis, FT-IR, 1H NMR and 13C NMR spectra. Crystal and molecular structures of the complexes were determined by single crystal X-ray diffraction method. Single crystal X-ray structural studies indicate that the hydrazone ligands coordinate to the VO core through enolate oxygen, phenolate oxygen and azomethine nitrogen. The V atoms in the complexes are in octahedral coordination. Thermal stabilities of the complexes have also been studied. DOI: http://dx.doi.org/10.4314/bcse.v29i3.10

  16. Preparation and structural characterization of corn starch-aroma compound inclusion complexes.

    Science.gov (United States)

    Zhang, Shu; Zhou, Yibin; Jin, Shanshan; Meng, Xin; Yang, Liping; Wang, Haisong

    2017-01-01

    Six corn starch inclusion complexes were synthesized using small nonpolar or weak polar aroma compounds (heptanolide, carvone and menthone) and small polar aroma compounds (linalool, heptanol and menthol). The objectives of this study were to (a) investigate the ability of corn starch to form inclusion complexes with these aroma compounds and (b) characterize the structure of the corn starch inclusion complexes. The resulting inclusion ratios were 75.6, 36.9, 43.8, 91.9, 67.2 and 54.7% for heptanolide, carvone, menthone, linalool, heptanol and menthol respectively. The inclusion complexes had laminated structures with a certain amount of holes or blocky constructions. Compared with gelatinized corn starch, the transition temperatures, peak temperatures and enthalpies of the inclusion complexes were significantly different. The major peak of CO at 1771 cm-1 and significant peak shifts revealed the formation of inclusion complexes. X-ray diffractometry (XRD) analyses revealed that the crystallinity of corn starch-polar aroma compound inclusion complexes increased. Based on cross-polarization magic angle spinning 13 C nuclear magnetic resonance (CP-MAS 13 C NMR) results, novel peaks and chemical shifts were attributed to the presence of small aroma compounds, thereby confirming the formation of corn starch inclusion complexes. Small nonpolar and polar aroma compounds can be complexed to corn starch. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  17. Flexible and Asymmetric Ligand in Constructing Coordinated Complexes: Synthesis, Crystal Structures and Fluorescent Characterization

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    Jianhua Lin

    2010-12-01

    Full Text Available Flexible and asymmetric ligand L [L = 1-((pyridin-3-ylmethyl-1H-benzotriazole], is used as a basic backbone to construct complicated metal-organic frameworks. Two new polymers, namely, [Ag2(L2(NO32]n (1 and [Ag(L(ClO4]n (2, were synthesized and characterized by X-ray structure analysis and fluorescent spectroscopy. The complex 1 gives an “S” type double helical conformation, whereas complex 2 exhibits a 1D zigzag configuration. Different anions affect the silver coordination geometry and crystal packing topology.

  18. A model based bayesian solution for characterization of complex damage scenarios in aerospace composite structures.

    Science.gov (United States)

    Reed, H; Leckey, Cara A C; Dick, A; Harvey, G; Dobson, J

    2018-01-01

    Ultrasonic damage detection and characterization is commonly used in nondestructive evaluation (NDE) of aerospace composite components. In recent years there has been an increased development of guided wave based methods. In real materials and structures, these dispersive waves result in complicated behavior in the presence of complex damage scenarios. Model-based characterization methods utilize accurate three dimensional finite element models (FEMs) of guided wave interaction with realistic damage scenarios to aid in defect identification and classification. This work describes an inverse solution for realistic composite damage characterization by comparing the wavenumber-frequency spectra of experimental and simulated ultrasonic inspections. The composite laminate material properties are first verified through a Bayesian solution (Markov chain Monte Carlo), enabling uncertainty quantification surrounding the characterization. A study is undertaken to assess the efficacy of the proposed damage model and comparative metrics between the experimental and simulated output. The FEM is then parameterized with a damage model capable of describing the typical complex damage created by impact events in composites. The damage is characterized through a transdimensional Markov chain Monte Carlo solution, enabling a flexible damage model capable of adapting to the complex damage geometry investigated here. The posterior probability distributions of the individual delamination petals as well as the overall envelope of the damage site are determined. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Facile synthesis and structural characterization of amylose-Fatty Acid inclusion complexes.

    Science.gov (United States)

    Cao, Zheng; Woortman, Albert J J; Rudolf, Petra; Loos, Katja

    2015-05-01

    Amylose-fatty acid inclusion complexes can be easily prepared by simple mixing in hot aqueous solutions. Above a critical chain length (C6) of the fatty acid insoluble complexes between amylose and each fatty acid (C8, C10, C12, C14, C16) were precipitated from the solution, and characterized by FT-IR, XRD, DSC, and SEC. The presence of the characteristic (CO) FT-IR absorption peak at 1 710 cm(-1) confirmed the inclusion of the fatty acids inside the amylose helix. XRD showed the same characteristic features of the V amylose single helical structure. Both SEC and DSC revealed that longer fatty acids can form inclusion complexes with amylose fractions having higher degree of polymerization, leading to greater yields, and higher thermal stability (higher melting temperature and enthalpy) of the amylose-complexes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Using LiDAR Metrics to Characterize Forest Structural Complexity at Multiple Scales

    Science.gov (United States)

    Kane, V. R.; McGaughey, R. J.; Gersonde, R.; Franklin, J. F.

    2007-12-01

    Forest structure - the size and arrangement of trees and foliage - reflects a stand's history of initiation, growth, disturbance, and mortality. Because of this, studying the structure of forests can provide key insights into ecological processes, guides to silvicultural prescriptions to improve habitat, and assessments of forested landscapes. This study tested LiDAR metrics to characterize stands based on canopy structure. The study site was the 34,591 ha of forests in the Cedar River Watershed in western Washington State, USA. Stands ranged in age from 350 years old (including old-growth). Study sites spanned the western hemlock- Douglas fir (Tsuga heterophylla-Pseudotsuga menziesii), Pacific silver fir (Abies amabilis), and mountain hemlock (Tsuga mertansiana) forest zones. Eighty sample plots were used to ground truth the LiDAR data. A variety of structural indices were used to study canopy structural variations at the plot, stand, and landscape scales. The two most successful indices used the exposed geometry of the canopy surface: (1) the ratio of the canopy surface area to ground surface area (rumple index), and (2) the ratio of the volume beneath the canopy surface to maximum volume beneath the 95th percentile height (modified canopy volume method). These two indices integrated the spatial effects of tree heights, foliage distribution, and tree arrangement within 15m pixels. Variation between pixels revealed structural complexity at larger scales. Results: At the plot scale (~4 pixels), correlations with standard plot metrics (e.g., diameter at breast height) were similar to those reported by other studies. Comparison of structural complexity with age and height revealed a diversity of development pathways. The relationship between height and complexity allowed stands to be classified by the degree to which they have achieved their potential structural complexity, a new way to examine forest development. At the stand scale, the indices allowed spatial

  1. Synthesis, structural characterization and crystal structure of some dimethyltin complexes containing substituted 1,10-phenanthroline

    Science.gov (United States)

    Momeni, Badri Z.; Haghshenas, Fahimeh; Hadi, Saba

    2017-08-01

    The reaction of dimethyltin dichloride with four substituted 1, 10- phenanthroline has been studied. The reactions of dimethyltin dichloride with 5-methyl-1,10-phenanthroline (Mephen); 5,6-dimethyl-1,10-phenanthroline (Me2phen); 5-nitro-1,10-phenanthroline (NO2phen); 5-chloro-1,10-phenanthroline (Clphen) resulted in the formation of the hexa-coordinated complexes of [SnMe2Cl2(NN)] {Mephen (1), Me2phen (2), NO2phen (3), Clphen (4)}. The resulting products have been fully characterized by elemental analysis, multinuclear (1H, 13C, 119Sn) NMR, DEPT-135, HHCOSY and HSQC NMR spectroscopy. The solid state X-ray determination of complexes [SnMe2Cl2(Mephen)] (1) and [SnMe2Cl2(Me2phen)] (2) revealed that the complexes 1 and 2 contain the hexa-coordinated tin(IV) atom in an octahedral geometry with the trans-[SnMe2] configuration. The Snsbnd N bond distances in 1-2 are 2.47-2.48 Å which are almost among the largest values.

  2. Unexpected structural complexity of supernumerary marker chromosomes characterized by microarray comparative genomic hybridization

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    Hing Anne V

    2008-04-01

    Full Text Available Abstract Background Supernumerary marker chromosomes (SMCs are structurally abnormal extra chromosomes that cannot be unambiguously identified by conventional banding techniques. In the past, SMCs have been characterized using a variety of different molecular cytogenetic techniques. Although these techniques can sometimes identify the chromosome of origin of SMCs, they are cumbersome to perform and are not available in many clinical cytogenetic laboratories. Furthermore, they cannot precisely determine the region or breakpoints of the chromosome(s involved. In this study, we describe four patients who possess one or more SMCs (a total of eight SMCs in all four patients that were characterized by microarray comparative genomic hybridization (array CGH. Results In at least one SMC from all four patients, array CGH uncovered unexpected complexity, in the form of complex rearrangements, that could have gone undetected using other molecular cytogenetic techniques. Although array CGH accurately defined the chromosome content of all but two minute SMCs, fluorescence in situ hybridization was necessary to determine the structure of the markers. Conclusion The increasing use of array CGH in clinical cytogenetic laboratories will provide an efficient method for more comprehensive characterization of SMCs. Improved SMC characterization, facilitated by array CGH, will allow for more accurate SMC/phenotype correlation.

  3. Structural characterization of the NAP; the major adhesion complex of the human pathogen Mycoplasma genitalium.

    Science.gov (United States)

    Scheffer, Margot P; Gonzalez-Gonzalez, Luis; Seybert, Anja; Ratera, Mercè; Kunz, Michael; Valpuesta, José M; Fita, Ignacio; Querol, Enrique; Piñol, Jaume; Martín-Benito, Jaime; Frangakis, Achilleas S

    2017-09-01

    Mycoplasma genitalium, the causative agent of non-gonococcal urethritis and pelvic inflammatory disease in humans, is a small eubacterium that lacks a peptidoglycan cell wall. On the surface of its plasma membrane is the major surface adhesion complex, known as NAP that is essential for adhesion and gliding motility of the organism. Here, we have performed cryo-electron tomography of intact cells and detergent permeabilized M. genitalium cell aggregates, providing sub-tomogram averages of free and cell-attached NAPs respectively, revealing a tetrameric complex with two-fold rotational (C2) symmetry. Each NAP has two pairs of globular lobes (named α and β lobes), arranged as a dimer of heterodimers with each lobe connected by a stalk to the cell membrane. The β lobes are larger than the α lobes by 20%. Classification of NAPs showed that the complex can tilt with respect to the cell membrane. A protein complex containing exclusively the proteins P140 and P110, was purified from M. genitalium and was structurally characterized by negative-stain single particle EM reconstruction. The close structural similarity found between intact NAPs and the isolated P140/P110 complexes, shows that dimers of P140/P110 heterodimers are the only components of the extracellular region of intact NAPs in M. genitalium. © 2017 John Wiley & Sons Ltd.

  4. Distorted tetrahedral nickel-nitrosyl complexes: spectroscopic characterization and electronic structure.

    Science.gov (United States)

    Soma, Shoko; Van Stappen, Casey; Kiss, Mercedesz; Szilagyi, Robert K; Lehnert, Nicolai; Fujisawa, Kiyoshi

    2016-09-01

    The linear nickel-nitrosyl complex [Ni(NO)(L3)] supported by a highly hindered tridentate nitrogen-based ligand, hydrotris(3-tertiary butyl-5-isopropyl-1-pyrazolyl)borate (denoted as L3), was prepared by the reaction of the potassium salt of the ligand with the nickel-nitrosyl precursor [Ni(NO)(Br)(PPh 3 ) 2 ]. The obtained nitrosyl complexes as well as the corresponding chlorido complexes [Ni(NO)(Cl)(PPh 3 ) 2 ] and [Ni(Cl)(L3)] were characterized by X-ray crystallography and different spectroscopic methods including IR/far-IR, UV-Vis, NMR, and multi-edge X-ray absorption spectroscopy at the Ni K-, Ni L-, Cl K-, and P K-edges. For comparative electronic structure analysis we also performed DFT calculations to further elucidate the electronic structure of [Ni(NO)(L3)]. These results provide the nickel oxidation state and the character of the Ni-NO bond. The complex [Ni(NO)(L3)] is best described as [Ni (II) (NO (-) )(L3)], and the spectroscopic results indicate that the phosphane complexes have a similar [Ni (II) (NO (-) )(X)(PPh 3 ) 2 ] ground state.

  5. Synthesis, structural characterization and photoluminescence properties of a novel La(III) complex

    Science.gov (United States)

    Köse, Muhammet; Ceyhan, Gökhan; Atcı, Emine; McKee, Vickie; Tümer, Mehmet

    2015-05-01

    In this study, a novel La(III) complex [La(H2L)2(NO3)3(MeOH)] of a Schiff base ligand was synthesized and characterized by spectroscopic and analytical methods. Single crystals of the complex suitable for X-ray diffraction study were obtained by slow diffusion of diethyl ether into a MeOH solution of the complex which was found to crystallise as [La(H2L)2(NO3)3(MeOH)]ṡ2MeOHṡH2O. The structure was solved in monoclinic crystal system, P21/n space group with unit cell parameters a = 10.5641(11), b = 12.6661(16), c = 16.0022(17) Å, α = 67.364(2), β = 83.794(2)°, γ = 70.541(2)°, V = 1862.9(4) Å3 and Z = 2 with R final value of 0.526. In the complex, the La(III) ion is ten-coordinated by O atoms, five of which come from three nitrate ions, four from the two Schiff base ligands and one from MeOH oxygen atom. The Schiff base ligands in the structure are in a zwitter ion form with the phenolic H transferred to the imine N atom. Thermal properties of the La(III) complex were examined by thermogravimetric analysis and the complex was found to be thermally stable up to 310 °C. The Schiff base ligand and its La(II) complex were screened for their in vitro antimicrobial activity against Bacillus megaterium, Staphylococcus aureus, Bacillus subtilis, Micrococcus luteus (Gram positive bacteria), Klebsiella pneumonia, Escherichia coli, Enterobacter aerogenes, Pseudomonas aeruginosa (Gram negative bacteria), Candida albicans,Yarrowia lipolytica (fungus) and Saccharomyces cerevisiae (yeast). The complex shows more antimicrobial activity than the free ligand.

  6. Spectral characterization, crystal structures and biological activities of iminodiacetate ternary complexes

    Science.gov (United States)

    Shahid, M.; Anjuli; Tasneem, Sana; Mantasha, I.; Ahamad, M. Naqi; Sama, Farasha; Fatma, Kehkeshan; Siddiqi, Zafar A.

    2017-10-01

    The ternary complexes with stoichiometry [M(imda)(bipy)]·6H2O (M = Cu) and [M(imda)(bipy)(H2O)]·4H2O (M = Ni, Co and Mn) where H2imda = iminodiacetic acid and bipy = 2,2‧-bipyridine, are prepared and characterized to exploit as novel antimicrobial agents and SOD mimics. The chemical structures were elucidated by IR, FAB-Mass, 1H, 13C NMR, EPR and spectral techniques. Single crystal X-ray and spectral studies of the complexes (1) and (2) have confirmed a square pyramidal geometry around Cu(II) ion while a saturated six coordinate (distorted octahedral) geometry around the Ni(II), Co(II) and Mn(II) ions due to the additional coordination from water. A supramolecular network is formed by extensive H-bonding in complex (1). The supramolecular assembly in complex (1) is additionally consolidated via the existence of unusual cyclic hexameric water clusters. The antimicrobial activities for the present complexes have been examined against Escherichia coli (K-12), Bacillus subtilis (MTC-121), Staphylococcus aureus (IOASA-22), Salmonella typhymurium (MTCC-98), Candida albicans, Aspergillus fumigatus and Penicillium marneffei. The superoxide dismutase (SOD) activity of the Cu(II) complex (1) is also assessed employing nitrobluetetrazolium (NBT) assay.

  7. Uranyl Sequestration: Synthesis and Structural Characterization of Uranyl Complexes with a Tetradentate Methylterephthalamide Ligand

    Energy Technology Data Exchange (ETDEWEB)

    Ni, Chengbao; Shuh, David; Raymond, Kenneth

    2011-03-07

    Uranyl complexes of a bis(methylterephthalamide) ligand (LH{sub 4}) have been synthesized and characterized by X-ray crystallography. The structure is an unexpected [Me{sub 4}N]{sub 8}[L(UO{sub 2})]{sub 4} tetramer, formed via coordination of the two MeTAM units of L to two uranyl moieties. Addition of KOH to the tetramer gave the corresponding monomeric uranyl methoxide species [Me{sub 4}N]K{sub 2}[LUO{sub 2}(OMe)].

  8. Crystal structure, spectroscopic characterization and antibacterial activities of a silver complex with sulfameter

    Science.gov (United States)

    Nakahata, Douglas H.; Lustri, Wilton R.; Cuin, Alexandre; Corbi, Pedro P.

    2016-12-01

    A silver complex with the sulfonamide sulfameter, also known as sulfamethoxydiazine (SMTR), was prepared and characterized. Chemical analyses were consistent with the [Ag(C11H11N4O3S)] composition (AgSMTR), while conductivity measurements in DMSO indicated a non-electrolyte behavior of the complex in this solvent. High-resolution ESI(+)-QTOF mass spectrometric experiments revealed the presence of the [Ag(C11H11N4O3S)+H]+ and [Ag2(C11H11N4O3S)2+H]+ species in solution. Infrared and NMR spectroscopies indicated coordination of the ligand to the metal by the nitrogen atoms of the sulfonamide group and of the pyrimidine ring. The structure of AgSMTR was solved by powder X-ray diffraction technique using the Rietveld method. The solved structure confirms the formation of a dimer, where each silver ion is coordinated by one of the nitrogen atoms of the pyrimidine ring, the nitrogen of the sulfonamide group and by an oxygen atom from the sulfonyl group. An argentophilic interaction of 2.901(1) Å is present in this dimeric structure. The AgSMTR complex was assayed over Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa and Escherichia coli) bacterial strains, and it was found that the compound is 8 times more active over the Gram-negative bacteria in DMSO solution, with MIC values in the micromolar range.

  9. Copper(I Complexes of Mesoionic Carbene: Structural Characterization and Catalytic Hydrosilylation Reactions

    Directory of Open Access Journals (Sweden)

    Stephan Hohloch

    2015-04-01

    Full Text Available Two series of different Cu(I-complexes of “click” derived mesoionic carbenes are reported. Halide complexes of the type (MICCuI (with MIC = 1,4-(2,6-diisopropyl-phenyl-3-methyl-1,2,3-triazol-5-ylidene (for 1b, 1-benzyl-3-methyl-4-phenyl-1,2,3-triazol-5-ylidene (for 1c and cationic complexes of the general formula [Cu(MIC2]X (with MIC =1,4-dimesityl-3-methyl-1,2,3-triazol-5-ylidene, X = CuI2− (for 2á, 1,4-dimesityl-3-methyl-1,2,3-triazol-5-ylidene, X = BF4− (for 2a, 1,4-(2,6-diisopropylphenyl-3-methyl-1,2,3-triazol-5-ylidene, X = BF4− (for 2b, 1-benzyl-3-methyl-4-phenyl-1,2,3-triazol-5-ylidene, X = BF4− (for 2c have been prepared from CuI or [Cu(CH3CN4](BF4 and the corresponding ligands, respectively. All complexes were characterized by elemental analysis and standard spectroscopic methods. Complexes 2á and 1b were studied by single-crystal X-ray diffraction analysis. Structural analysis revealed 2á to adopt a cationic form as [Cu(MIC2](CuI2 and comparison of the NMR spectra of 2á and 2a confirmed this conformation in solution. In contrast, after crystallization complex 1b was found to adopt the desired neutral form. All complexes were tested for the reduction of cyclohexanone under hydrosilylation condition at elevated temperatures. These complexes were found to be efficient catalysts for this reaction. 2c was also found to catalyze this reaction at room temperature. Mechanistic studies have been carried out as well.

  10. Complex of hexamethylenetetramine with magnesium-tetraphenylporphyrin: Synthesis, structure, spectroscopic characterizations and electrochemical properties

    Science.gov (United States)

    Ezzayani, Khaireddine; Ben Khelifa, Arbia; Saint-Aman, Eric; Loiseau, Frederique; Nasri, Habib

    2017-06-01

    A new crystalline material of a magnesium (II)-porphyrin complex was prepared and characterized by single crystal X-ray diffraction. The molecular structure is made by (5,10,15,20-tetraphenylporphyrinato-κ4N)bis(hexamethylenetetramine) magnesium dichloromethane disolvate. The title compound crystallizes in the orthorhombic system, space group Pbcn, with a = 19.2932 (6) Å, b = 10.4878 (4) Å, c = 26.0025 (14) Å, V = 5261.4 (4) Å3 and Z = 4. The supramolecular architecture includes weak C__H⋯N hydrogen bond. This magnesium-porphyrin species was also characterized by UV-visible, IR and fluorescence spectroscopy and a cyclic voltammetry investigation was also carried out on this species.

  11. Bimetallic octahedral ruthenium-nickel carbido cluster complexes. Synthesis and structural characterization.

    Science.gov (United States)

    Saha, Sumit; Zhu, Lei; Captain, Burjor

    2013-03-04

    The reaction of Ru5(CO)15(μ5-C) with Ni(COD)2 in acetonitrile at 80 °C affords the bimetallic octahedral ruthenium-nickel cluster complex Ru5Ni(NCMe)(CO)15(μ6-C), 3. The acetonitrile ligand in 3 can be replaced by CO and NH3 to yield Ru5Ni(CO)16(μ6-C), 4, and Ru5Ni(NH3)(CO)15(μ6-C), 5, respectively. Photolysis of compound 3 in benzene and toluene solvent yielded the η(6)-coordinated benzene and toluene Ru5Ni carbido cluster complexes Ru5Ni(CO)13(η(6)-C6H6)(μ6-C), 6, and Ru5Ni(CO)13(η(6)-C7H8)(μ6-C), 7, respectively. All five new compounds were structurally characterized by single-crystal X-ray diffraction analyses.

  12. Synthesis, characterization, crystal structure and electrochemical studies of ionic iron(III) dipicolinato complex

    Science.gov (United States)

    Ghasemi, Fatemeh; Ghasemi, Khaled; Rezvani, Ali Reza; Rosli, Mohd Mustaqim; Razak, Ibrahim Abdul

    2017-09-01

    The new complex (NH4)[Fe(dipic)2] (1) (dipicH2 = 2,6-pyridinedicarboxylic acid), was synthesized and characterized by elemental analysis, FTIR and UV-Vis spectroscopy and single crystal X-ray method. The crystal system is tetragonal with space group I41/a. The FeIII ion and the N atom of the ammonium cation are located on a crystallographic fourfold rotoinversion axis (4 bar). The Nsbnd H⋯O and Csbnd H⋯O intermolecular hydrogen bonding and π⋯π stacking interactions play an important role in the formation of a 3-dimensional anion-cation network and stabilization of the crystal structure. The redox behavior of the complex was also investigated by cyclic voltammetry.

  13. Facile Synthesis and Structural Characterization of Amylose-Fatty Acid Inclusion Complexes

    NARCIS (Netherlands)

    Cao, Zheng; Woortman, Albert; Rudolf, Petra; Loos, Katja

    2015-01-01

    Amylose-fatty acid inclusion complexes can be easily prepared by simple mixing in hot aqueous solutions. Above a critical chain length (C6) of the fatty acid insoluble complexes between amylose and each fatty acid (C8, C10, C12, C14, C16) were precipitated from the solution, and characterized by

  14. Structural Characterization of Emeraldine-Salt Polyaniline/Gold Nanoparticles Complexes

    Directory of Open Access Journals (Sweden)

    E. A. Sanches

    2011-01-01

    Full Text Available Gold nanoparticles (Au NPs stabilized with polyamidoamine dendrimers (Au-PAMAM or sodium citrate (Au-CITRATE were synthesized and complexed with polyaniline emeraldine-salt form (ES-PANI. The complexes were characterized using structural and morphological techniques, including X-Ray Diffraction (XRD, Scanning Electron Microscopy (SEM, Zeta Potential analyses, and Fourier-Transformed Infrared spectroscopy (FTIR. When the Au-CITRATE NPs are added to the polymeric solution, the formation of a precipitate is clearly observed. The precipitate exhibited a different morphology from that found for ES-PANI and Au-CITRATE NPs, suggesting the formation of ES-PANI coating over the surface of Au-CITRATE NPs. On the other hand, when the Au-PAMAM NPs are incorporated into the ES-PANI solution, none interaction was observed, probably due to the repulsive electrostatic interactions, being the organization of the ES-PANI chains unaffected by the presence of the Au-PAMAM NPs.

  15. Synthesis, characterization, and crystal structure of mercury(II) complex containing new phosphine oxide salt

    Science.gov (United States)

    Samiee, Sepideh; Kooti, Nadieh; Gable, Robert W.

    2017-02-01

    The reaction of new phosphonium-phosphine oxide salt [P(O)Ph2(CH2)2PPh2CH2C(O)C6H4NO2]Br (1) with mercury(II) iodide in a methanolic solution yielded [P(O)Ph2(CH2)2PPh2CH2C(O)C6H4NO2]2[Hg2I5Br](2). These two compounds were fully characterized by elemental analysis, IR, 1H, 31P, and 13C NMR spectra. Crystal and molecular structure of 2 has been determined by means of X-ray diffraction. In mercury compound, the phosphine oxide salt is found as a counter ion letting the mercury(II) ion to bound halides to all four coordination sites and to give dimermercurate(II) ions as the structure-constructing species. The neighboring [P(O)Ph2(CH2)2PPh2CH2C(O)C6H4NO2]2+cations are joined together by intramolecular Csbnd H⋯O hydrogen bonds to give a 1-D chain structure along the crystallographic b-axis. The [Hg2I5Br]2-anions act as cross-linkers between neighbouring strands extending the supramolecular structure into 2D layers in (110) planes as well as balances the charge of the complex. The significant effects of Csbnd H⋯X (Xdbnd O, Br and I) and π⋯π aromatic interactions play a major role in the crystal packing of compound 2.

  16. Structural Characterization of Tip20p and Dsl1p, Subunits of the Dsl1p Vesicle Tethering Complex

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, A.; Ren, Y; Jeffrey, P; Hughson, F

    2009-01-01

    Multisubunit tethering complexes are essential for intracellular trafficking and have been proposed to mediate the initial interaction between vesicles and the membranes with which they fuse. Here we report initial structural characterization of the Dsl1p complex, whose three subunits are essential for trafficking from the Golgi apparatus to the endoplasmic reticulum (ER). Crystal structures reveal that two of the three subunits, Tip20p and Dsl1p, resemble known subunits of the exocyst complex, establishing a structural connection among several multisubunit tethering complexes and implying that many of their subunits are derived from a common progenitor. We show, moreover, that Tip20p and Dsl1p interact directly via N-terminal alpha-helices. Finally, we establish that different Dsl1p complex subunits bind independently to different ER SNARE proteins. Our results map out two alternative protein-interaction networks capable of tethering COPI-coated vesicles, via the Dsl1p complex, to ER membranes.

  17. Syntheses, crystal structures and characterization of divalent transition metal sulfonate complexes with o-phenanthroline

    Science.gov (United States)

    Yang, Jin; Ma, Jian-Fang; Wu, Dong-Mei; Guo, Li-Ping; Liu, Jing-Fu

    2003-09-01

    Three new complexes, namely [Cu(phen)(L)(H 2O) 2]L·H 2O 1, [M(phen) 2(H 2O) 2]2L·6H 2O [M=Co( 2), Ni( 3)], where, HL=4-methylbenzenesulfonic acid and phen= o-phenanthroline, have been synthesized. The crystal structures were determined by X-ray diffraction method and refined by full-matrix least-squares methods to R=0.0535 and wR=0.1492 using 3567 reflections with I>2 σ( I) for 1; R=0.0388 and wR=0.1223 using 3844 reflections with I>2 σ( I) for 2; and R=0.0401 and wR=0.1222 using 3425 reflections with I>2 σ( I) for 3. 1 Consists of cationic species [Cu(phen)(L)(H 2O) 2] +, in which Cu(II) ion is five-coordinated by two nitrogen atoms of o-phenanthroline, two water molecules and one sulfonate oxygen atom. The cations and the non-coordinating sulfonate anions are linked by hydrogen bonds to form infinite chains. Complexes 2 and 3 are isostructral compounds. Each of them consists of cationic species [M(phen) 2(H 2O) 2] 2+, in which metal ion is six-coordinated by four nitrogen atoms from two o-phenanthroline molecules and two water oxygen atoms. The sulfonate ions do not coordinate to metal ion. The cations, non-coordinating sulfonate ions and lattice water molecules are linked by hydrogen bonds to form infinite zigzag chains. CV, FT-IR, UV-Vis and TGA were also used to characterize these compounds.

  18. Synthesis and preliminary structural characterization of some lanthanide(III semicarbazone complex

    Directory of Open Access Journals (Sweden)

    Ram K. Agarwal

    2006-06-01

    Full Text Available Some six and nine coordinated complexes of trivalent lanthanide metal ions with 4[N-(2'-hydroxy-1'-naphthalideneamino]antipyrinesemicarbazone (HNAAPS with the general composition LnX3.n(HNAAPS [X = NO3, n = 1; X = NCS or ClO4, n = 2; Ln = La, Pr, Nd, Sm, Gd, Tb, Dy or Ho] have been isolated. All the complexes have been characterized on the basis of analytical data, molar conductance, magnetic susceptibility, electronic and infrared spectral measurements. The ligand HNAAPS behaves as neutral tridentate (N, N, O ligand. The coordination number of the central metal ion is either six or nine in these complexes. Thermal properties of these complexes were also investigated.

  19. Structural Characterization of a Thrombin-Aptamer Complex by High Resolution Native Top-Down Mass Spectrometry

    Science.gov (United States)

    Zhang, Jiang; Loo, Rachel R. Ogorzalek; Loo, Joseph A.

    2017-09-01

    Native mass spectrometry (MS) with electrospray ionization (ESI) has evolved as an invaluable tool for the characterization of intact native proteins and non-covalently bound protein complexes. Here we report the structural characterization by high resolution native top-down MS of human thrombin and its complex with the Bock thrombin binding aptamer (TBA), a 15-nucleotide DNA with high specificity and affinity for thrombin. Accurate mass measurements revealed that the predominant form of native human α-thrombin contains a glycosylation mass of 2205 Da, corresponding to a sialylated symmetric biantennary oligosaccharide structure without fucosylation. Native MS showed that thrombin and TBA predominantly form a 1:1 complex under near physiological conditions (pH 6.8, 200 mM NH4OAc), but the binding stoichiometry is influenced by the solution ionic strength. In 20 mM ammonium acetate solution, up to two TBAs were bound to thrombin, whereas increasing the solution ionic strength destabilized the thrombin-TBA complex and 1 M NH4OAc nearly completely dissociated the complex. This observation is consistent with the mediation of thrombin-aptamer binding through electrostatic interactions and it is further consistent with the human thrombin structure that contains two anion binding sites on the surface. Electron capture dissociation (ECD) top-down MS of the thrombin-TBA complex performed with a high resolution 15 Tesla Fourier transform ion cyclotron resonance (FTICR) mass spectrometer showed the primary binding site to be at exosite I located near the N-terminal sequence of the heavy chain, consistent with crystallographic data. High resolution native top-down MS is complementary to traditional structural biology methods for structurally characterizing native proteins and protein-DNA complexes. [Figure not available: see fulltext.

  20. Structural and functional characterization of protein complexes in the blood coagulation cascade

    DEFF Research Database (Denmark)

    Madsen, Jesper Jonasson

    are explained. Furthermore, the inter-domain linker connecting the two epidermal growth factor-like domains of FVIIa will be discussed with respect to consequences for its ability to form a productive complex with tissue factor. Finally, membrane binding of FVIIIa as mediated by the tandem C2-like domains...... processes, complex formation, and platelet membrane association. Both the intrinsic and the extrinsic tenase complex consists of a trypsin-like serine protease and auxiliary domains complexed with the appropriate cofactor; FIXa with FVIIIa and FVIIa with tissue factor (TF), respectively. Topics covered...... will include the structural and dynamical changes upon proteolytic activation and TF-induced allosteric activation of FVIIa. In addition, FVIIa variants with the 170-loop grafted from trypsin will be looked into and, in particular, the mechanisms that enable these variants to have increased activity without TF...

  1. Characterization of measurement errors using structure-from-motion and photogrammetry to measure marine habitat structural complexity.

    Science.gov (United States)

    Bryson, Mitch; Ferrari, Renata; Figueira, Will; Pizarro, Oscar; Madin, Josh; Williams, Stefan; Byrne, Maria

    2017-08-01

    Habitat structural complexity is one of the most important factors in determining the makeup of biological communities. Recent advances in structure-from-motion and photogrammetry have resulted in a proliferation of 3D digital representations of habitats from which structural complexity can be measured. Little attention has been paid to quantifying the measurement errors associated with these techniques, including the variability of results under different surveying and environmental conditions. Such errors have the potential to confound studies that compare habitat complexity over space and time. This study evaluated the accuracy, precision, and bias in measurements of marine habitat structural complexity derived from structure-from-motion and photogrammetric measurements using repeated surveys of artificial reefs (with known structure) as well as natural coral reefs. We quantified measurement errors as a function of survey image coverage, actual surface rugosity, and the morphological community composition of the habitat-forming organisms (reef corals). Our results indicated that measurements could be biased by up to 7.5% of the total observed ranges of structural complexity based on the environmental conditions present during any particular survey. Positive relationships were found between measurement errors and actual complexity, and the strength of these relationships was increased when coral morphology and abundance were also used as predictors. The numerous advantages of structure-from-motion and photogrammetry techniques for quantifying and investigating marine habitats will mean that they are likely to replace traditional measurement techniques (e.g., chain-and-tape). To this end, our results have important implications for data collection and the interpretation of measurements when examining changes in habitat complexity using structure-from-motion and photogrammetry.

  2. Coordination diversity of new mononucleating hydrazone in 3d metal complexes: Synthesis, characterization and structural studies

    Directory of Open Access Journals (Sweden)

    RAJESH S. BALIGAR

    2006-12-01

    Full Text Available The mononucleating hydrazone ligand LH3, a condensation product of salicyloylhydrazine and (2-formylphenoxyacetic acid, was synthesized and its coordination behavior with first row transition metal(II ions was investigated by isolating and elucidating the structure of the complexes using elemental analysis, conductivity and magnetic susceptibility measurements, as well as IR, 1H-NMR, electronic and EPR spectral techniques. The ligand forms mononuclear metal(II complexes of the type [CoLH(H2O2], [NiLH(H2O2, [CuLH] and [ZnLH]. The ligand field parameters, Dq, B and b values, in the case of the cobalt and nickel complexes support not only the octahedral geometry around the metal ion, but also imply the covalent nature of the bonding in the complexes. The EPR study revealed the presence of a spin exchange interaction in the solid copper complex and the covalent nature of the bonding. The 1H-NMR study of the zinc(II complex indicated the non-involvement of the COOH group in the coordination. The physico-chemical study supports for the presence of octahedral geometry around cobalt(II, nickel(II and tetrahedral geometry around copper(II and zinc(II ions.

  3. Dioxidovanadium(V complexes with pyridoxalaminoguanidine: Synthesis, spectral and structural characterization

    Directory of Open Access Journals (Sweden)

    Lalović Mirjana M.

    2013-01-01

    Full Text Available Three square-pyramidal complexes of dioxidovanadium(V with pyridoxalaminoguanidine (PLAG, of the formulas NH4[VO2(PLAG−2H]∙H2O (1, VO2(PLAG−H (2 and K[VO2(PLAG−2H]∙H2O (3 have been synthesized and characterized by IR and UV-Vis spectral analysis and in case of 1 and 3 by X-ray crystallography as well. The reaction of aqueous ammoniacal solution of NH4VO3 and PLAG resulted in formation of 1, which in MeOH undergoes spontaneous transformation into 2, which, in turn, in the reaction with KOH transforms into 3. In these complexes PLAG is coordinated in a common tridentate ONN mode, via phenoxide oxygen atom and nitrogen atoms of azomethine and imino groups of the aminoguanidine fragment. In all previously characterized complexes PLAG was coordinated in neutral form. However, here we have proven that this ligand can be coordinated in both mono- (2 and doubly deprotonated form (1 and 3 as well. [Projekat Ministarstva nauke Republike Srbije, br. 172014].

  4. Synthesis, Characterization, and Crystal Structure of a Triazine Anion Pentafluoroosmium(VI Complex

    Directory of Open Access Journals (Sweden)

    Monther A. Khanfar

    2018-01-01

    Full Text Available The synthesis and characterization of a novel triazine anion pentafluoroosmium(VI complex are presented. The single crystal determination of the title compound (hereafter denoted 1 was carried out at −140 °C. Compound 1, C3F4N3OsF5, crystallizes in the monoclinic space group, P21/n, with unit cell dimensions: a = 8.6809(17 Å, b = 7.6848(15 Å, c = 12.415(3 Å, β = 102.633(4°, V = 808.2(3 Å3, and Z = 4. Synthesis, characterization, X-ray diffraction study along with the crystal supramolecular analysis of the title complex were carried out. The complex contains the anionic triazine unit C3N3F4− acting as a mono dentate ligand to osmium(VI with five fluoro ligands in a slightly distorted octahedral geometry around osmium(VI ion (osmium is denoted as Os. The C3N3F4−, triazine anion ring deviates from planarity, only with the C1 being tetrahedral. The crystal lattice of the title compound displays significant intermolecular X···X interactions, namly F···F, F···N and F···C. All types of X···X bonding consolidate to form a three-dimensional network.

  5. Structural and thermodynamic characterization of cadherin·β-catenin·α-catenin complex formation.

    Science.gov (United States)

    Pokutta, Sabine; Choi, Hee-Jung; Ahlsen, Goran; Hansen, Scott D; Weis, William I

    2014-05-09

    The classical cadherin·β-catenin·α-catenin complex mediates homophilic cell-cell adhesion and mechanically couples the actin cytoskeletons of adjacent cells. Although α-catenin binds to β-catenin and to F-actin, β-catenin significantly weakens the affinity of α-catenin for F-actin. Moreover, α-catenin self-associates into homodimers that block β-catenin binding. We investigated quantitatively and structurally αE- and αN-catenin dimer formation, their interaction with β-catenin and the cadherin·β-catenin complex, and the effect of the α-catenin actin-binding domain on β-catenin association. The two α-catenin variants differ in their self-association properties: at physiological temperatures, αE-catenin homodimerizes 10× more weakly than does αN-catenin but is kinetically trapped in its oligomeric state. Both αE- and αN-catenin bind to β-catenin with a Kd of 20 nM, and this affinity is increased by an order of magnitude when cadherin is bound to β-catenin. We describe the crystal structure of a complex representing the full β-catenin·αN-catenin interface. A three-dimensional model of the cadherin·β-catenin·α-catenin complex based on these new structural data suggests mechanisms for the enhanced stability of the ternary complex. The C-terminal actin-binding domain of α-catenin has no influence on the interactions with β-catenin, arguing against models in which β-catenin weakens actin binding by stabilizing inhibitory intramolecular interactions between the actin-binding domain and the rest of α-catenin.

  6. Structural and Thermodynamic Characterization of Cadherin·β-Catenin·α-Catenin Complex Formation*

    Science.gov (United States)

    Pokutta, Sabine; Choi, Hee-Jung; Ahlsen, Goran; Hansen, Scott D.; Weis, William I.

    2014-01-01

    The classical cadherin·β-catenin·α-catenin complex mediates homophilic cell-cell adhesion and mechanically couples the actin cytoskeletons of adjacent cells. Although α-catenin binds to β-catenin and to F-actin, β-catenin significantly weakens the affinity of α-catenin for F-actin. Moreover, α-catenin self-associates into homodimers that block β-catenin binding. We investigated quantitatively and structurally αE- and αN-catenin dimer formation, their interaction with β-catenin and the cadherin·β-catenin complex, and the effect of the α-catenin actin-binding domain on β-catenin association. The two α-catenin variants differ in their self-association properties: at physiological temperatures, αE-catenin homodimerizes 10× more weakly than does αN-catenin but is kinetically trapped in its oligomeric state. Both αE- and αN-catenin bind to β-catenin with a Kd of 20 nm, and this affinity is increased by an order of magnitude when cadherin is bound to β-catenin. We describe the crystal structure of a complex representing the full β-catenin·αN-catenin interface. A three-dimensional model of the cadherin·β-catenin·α-catenin complex based on these new structural data suggests mechanisms for the enhanced stability of the ternary complex. The C-terminal actin-binding domain of α-catenin has no influence on the interactions with β-catenin, arguing against models in which β-catenin weakens actin binding by stabilizing inhibitory intramolecular interactions between the actin-binding domain and the rest of α-catenin. PMID:24692547

  7. Structural characterization of human heme oxygenase-1 in complex with azole-based inhibitors.

    Science.gov (United States)

    Rahman, Mona N; Vlahakis, Jason Z; Roman, Gheorghe; Vukomanovic, Dragic; Szarek, Walter A; Nakatsu, Kanji; Jia, Zongchao

    2010-03-01

    The development of inhibitors specific for heme oxygenases (HO) aims to provide powerful tools in understanding the HO system. Based on the lead structure (2S, 4S)-2-[2-(4-chlorophenyl)ethyl]-2-[(1H-imidazol-1-yl)methyl]-4-[((4-aminophenyl)thio)methyl]-1,3-dioxolane (azalanstat, QC-1) we have synthesized structural modifications to develop novel and selective HO inhibitors. The structural study of human HO-1 (hHO-1) in complex with a select group of the inhibitors was initiated using X-ray crystallographic techniques. Comparison of the structures of four such compounds each in complex with hHO-1 revealed a common binding mode, despite having different structural fragments. The compounds bind to the distal side of heme through an azole "anchor" which coordinates with the heme iron. An expansion of the distal pocket, mainly due to distal helix flexibility, allows accommodation of the compounds without displacing heme or the critical Asp140 residue. Rather, binding displaces a catalytically critical water molecule and disrupts an ordered hydrogen-bond network involving Asp140. The presence of a triazole "anchor" may provide further stability via a hydrogen bond with the protein. A hydrophobic pocket acts to stabilize the region occupied by the phenyl or adamantanyl moieties of these compounds. Further, a secondary hydrophobic pocket is formed via "induced fit" to accommodate bulky substituents at the 4-position of the dioxolane ring. Copyright 2009 Elsevier Inc. All rights reserved.

  8. Structural and spectroscopic characterization of copper(I) halogen complexes with omega-thiocaprolactam and triphenylphosphine

    NARCIS (Netherlands)

    Luic, M; KojicProdic, B; Herrema, J; Akrivos, PD; Karagiannidis, P

    1995-01-01

    A series of mixed ligand copper(I) halogeno complexes with omega-thiocaprolactam, (tclH) and triphenylphosphine (PPh(3)) of general formula Cu(tclH)(n)(PPh(3))(3-n)X where n = 1, 2 and X = CI, Pr, I has been studied. The crystal structure of Cu(tclH)(PPH3)(2)Br is reported and discussed with respect

  9. Synthesis, characterization, and crystal structures of diruthenium complexes containing bridging salicylato ligands

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Mingxuan; Yau, Chun Huan; Hu, Yuxin; Tan, Yong Leng Kelvin [Hwa Chong Institution (Singapore); Li, Yingzhou; Ganguly, Rakesh; Leong, Weng Kee [Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University (Singapore)

    2017-08-03

    The thermal reaction of Ru{sub 3}(CO){sub 12} (1) with salicylic acid, in the presence of triphenylphosphine, pyridine, or dimethylsulfoxide, afforded the dinuclear complexes Ru{sub 2}(CO){sub 4}(μ-O{sub 2}CC{sub 6}H{sub 4}OH){sub 2}L{sub 2} (2) [L = PPh{sub 3} (2a). C{sub 5}H{sub 5}N (2b); (CH{sub 3}){sub 2}SO (2c)]. Complex 2b was further reacted with the aromatic dimmines 2,2'-dipyridine or 1,10-phenanthroline to give the cationic diruthenium complexes [Ru{sub 2}(CO){sub 2}(μ-CO){sub 2}(μ-O{sub 2}CC{sub 6}H{sub 4}OH)(N intersection N){sub 2}]{sup +} (3) [(N intersection N) = 2,2'-dipyridine (3a); 1,10-phenanthroline (3b)], which were isolated as their tetraphenylborate salts. All five novel complexes were characterized spectroscopically and analytically. For 2a-2b and 3a-3b, single-crystal X-ray diffraction studies were also carried out. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Copper(II) and palladium(II) complexes with tridentate NSO donor Schiff base ligand: Synthesis, characterization and structures

    Science.gov (United States)

    Kumar, Sujit Baran; Solanki, Ankita; Kundu, Suman

    2017-09-01

    Mononuclear copper(II) complex [CuL2] and palladium(II) complexes [Pd(X)L] where X = benzoate(bz) or salicylate(sal) and HL = 2-(methylthio)phenylimino)methyl)phenol, a Schiff base ligand with NSO coordination sites have been synthesized and characterized by microanalyses, IR, UV-Visible spectra, conductivity measurement and magnetic studies. Crystal structures of all the complexes have been solved by single crystal X-ray diffraction studies and showed that there are two molecules in a unit cell in the [CuL2] complex - one molecule has square planar geometry whereas second molecule has distorted square pyramidal geometry and palladium(II) complexes have distorted square planar geometry.

  11. Synthesis, structural characterization, cytotoxic properties and DNA binding of a dinuclear copper(II) complex.

    Science.gov (United States)

    Ferreira, B J M Leite; Brandão, P; Meireles, M; Martel, Fátima; Correia-Branco, Ana; Fernandes, Diana M; Santos, T M; Félix, V

    2016-08-01

    In this study a novel dinuclear copper(II) complex with adenine and phenanthroline has been synthesized and its structure determined by single crystal X-ray diffraction. In the dinuclear complex [Cu₂(μ-adenine)₂(phen)₂(H2O)2](NO3)4·0.5H2O (phen=1,10-phenanthroline) (1) the two Cu(II) centres exhibit a distorted square pyramidal coordination geometry linked by two nitrogen donors from adenine bridges leading to a Cu-Cu distance of 3.242(3)Å. Intramolecular and intermolecular π⋯π interactions as well as an H-bonding network were observed. The antitumor capacity of the complex has been tested in vitro against human cancer cell lines, cervical carcinoma (HeLa) and colorectal adenocarcinoma (Caco-2), by metabolic tests, using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide as reagent. The complex 1 has remarkable low IC50 values of 0.87±0.06μM (HeLa) and 0.44±0.06μM (Caco-2), when compared with values for cisplatin against the same cell lines. The interaction of complex 1 with calf thymus DNA (CT DNA) was further investigated by absorption and fluorescence spectroscopic methods. A binding constant of 5.09×10(5)M(-1) was obtained from UV-vis absorption studies. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Structural characterization of the ternary complex that mediates termination of NF-κB signaling by IκBα.

    Science.gov (United States)

    Mukherjee, Sulakshana P; Quintas, Pedro O; McNulty, Reginald; Komives, Elizabeth A; Dyson, H Jane

    2016-05-31

    The transcription factor NF-κB is used in many systems for the transduction of extracellular signals into the expression of signal-responsive genes. Published structural data explain the activation of NF-κB through degradation of its dedicated inhibitor IκBα, but the mechanism by which NF-κB-mediated signaling is turned off by its removal from the DNA in the presence of newly synthesized IκBα (termed stripping) is unknown. Previous kinetic studies showed that IκBα accelerates NF-κB dissociation from DNA, and a transient ternary complex between NF-κB, its cognate DNA sequence, and IκBα was observed. Here we structurally characterize the >100-kDa ternary complex by NMR and negative stain EM and show a modeled structure that is consistent with the measurements. These data provide a structural basis for previously unidentified insights into the molecular mechanism of stripping.

  13. Rheological and structural characterization of agar/whey proteins insoluble complexes.

    Science.gov (United States)

    Rocha, Cristina M R; Souza, Hiléia K S; Magalhães, Natália F; Andrade, Cristina T; Gonçalves, Maria Pilar

    2014-09-22

    Complex coacervation between whey proteins and carboxylated or highly sulphated polysaccharides has been widely studied. The aim of this work was to characterise a slightly sulphated polysaccharide (agar) and whey protein insoluble complexes in terms of yield, composition and physicochemical properties as well as to study their rheological behaviour for better understanding their structure. Unlike other sulphated polysaccharides, complexation of agar and whey protein at pH 3 in the absence of a buffering agent resulted in a coacervate that was a gel at 20°C with rheological properties and structure similar to those of simple agar gels, reinforced by proteins electrostatically aggregated to the agar network. The behaviour towards heat treatment was similar to that of agar alone, with a high thermal hysteresis and almost full reversibility. In the presence of citrate buffer, the result was a "flocculated solid", with low water content (75-81%), whose properties were governed by protein behaviour. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Directed weighted network structure analysis of complex impedance measurements for characterizing oil-in-water bubbly flow

    Science.gov (United States)

    Gao, Zhong-Ke; Dang, Wei-Dong; Xue, Le; Zhang, Shan-Shan

    2017-03-01

    Characterizing the flow structure underlying the evolution of oil-in-water bubbly flow remains a contemporary challenge of great interests and complexity. In particular, the oil droplets dispersing in a water continuum with diverse size make the study of oil-in-water bubbly flow really difficult. To study this issue, we first design a novel complex impedance sensor and systematically conduct vertical oil-water flow experiments. Based on the multivariate complex impedance measurements, we define modalities associated with the spatial transient flow structures and construct modality transition-based network for each flow condition to study the evolution of flow structures. In order to reveal the unique flow structures underlying the oil-in-water bubbly flow, we filter the inferred modality transition-based network by removing the edges with small weight and resulting isolated nodes. Then, the weighted clustering coefficient entropy and weighted average path length are employed for quantitatively assessing the original network and filtered network. The differences in network measures enable to efficiently characterize the evolution of the oil-in-water bubbly flow structures.

  15. Synthesis, structural characterization, crystal structure and theoretical study of a Pd(II)-salen complex with propylene linkage

    Science.gov (United States)

    Azam, Mohammad; Al-Resayes, Saud I.; Soliman, Saied M.; Kruszynska, Agata Trzesowska; Kruszynski, Rafal

    2017-06-01

    A Pd(II)-salen complex derived from salen ligand is reported. The reported complex is investigated by microanalyses (C, H, N), ESI-MS spectrometry, FT-IR, 1H and 13C NMR and UV/Vis spectroscopic studies. In addition, crystal structure measurement study has also been carried out in order to confirm the structure of Pd(II)-salen complex. In order to explore the insights into the structural bonding of the studied complex, computational measurements has been carried out. Combined topology and NBO studies were made to explore the nature of Pdsbnd O and Pdsbnd N bonding in the complex. The natural charges showed that the transfers of the negative charge from the ligand to palladium atom is at 1.4157-1.4312 e. Atom in a molecule (AIM) analysis showed the electron density (ρ(r) > 0.1) and its Laplacian (∇2 ρ(r) > 0). These topological parameters showed that covalent bonding interactions are dominant in Pdsbnd N and Pdsbnd O bonds. However, Pdsbnd N bonds have more covalent characters than Pdsbnd O bonds, which is further confirmed by the ratio of local electron potential energy density to the local electron kinetic energy density (|V(r)|/G(r)) found to be higher for Pdsbnd N bonds (1.1683-1.1993) as compared to Pdsbnd O bonds (1.0689-1.0926). AIM and NBO reveal that shorter Pdsbnd N and Pdsbnd O bonds have higher interaction energies (Eint) and hence higher bond covalence.

  16. Gallium and indium complexes containing the bis(imino)phenoxide ligand: synthesis, structural characterization and polymerization studies.

    Science.gov (United States)

    Ghosh, Swarup; Gowda, Ravikumar R; Jagan, Rajamony; Chakraborty, Debashis

    2015-06-14

    A series of gallium and indium complexes containing a bis(imino)phenolate ligand framework were synthesized and completely characterized with different spectroscopic techniques. The molecular structures of a few complexes were determined using single crystal X-ray diffraction studies. These compounds were found to be extremely active towards the bulk ring opening polymerization (ROP) of lactides yielding polymers with high number average molecular weight (Mn) and controlled molecular weight distributions (MWDs). The neutral complexes produce isotactic enriched poly(lactic acid) (PLA) from rac-lactide (rac-LA) under melt conditions, whereas the ionic complex produces atactic PLA. The polymerizations are controlled, as evidenced by the narrow molecular distribution (MWDs) of the isolated polymers in addition to the linear nature of number average molecular weight (Mn) versus conversion plots with variations in monomer to catalyst ratios. The kinetic and mechanistic studies associated with these polymerizations have been performed.

  17. Aroylhydrazone Cu(II Complexes in keto Form: Structural Characterization and Catalytic Activity towards Cyclohexane Oxidation

    Directory of Open Access Journals (Sweden)

    Manas Sutradhar

    2016-03-01

    Full Text Available The reaction of the Schiff base (3,5-di-tert-butyl-2-hydroxybenzylidene-2-hydroxybenzohydrazide (H3L with a copper(II salt of a base of a strong acid, i.e., nitrate, chloride or sulphate, yielded the mononuclear complexes [Cu(H2L(NO3(H2O] (1, [Cu(H2LCl]·2MeOH (2 and the binuclear complex [{Cu(H2L}2(µ-SO4]·2MeOH (3, respectively, with H2L− in the keto form. Compounds 1–3 were characterized by elemental analysis, Infrared (IR spectroscopy, Electrospray Ionisation Mass Spectrometry (ESI-MS and single crystal X-ray crystallography. All compounds act as efficient catalysts towards the peroxidative oxidation of cyclohexane to cyclohexyl hydroperoxide, cyclohexanol and cyclohexanone, under mild conditions. In the presence of an acid promoter, overall yields (based on the alkane up to 25% and a turnover number (TON of 250 (TOF of 42 h−1 after 6 h, were achieved.

  18. Aroylhydrazone Cu(II) Complexes in keto Form: Structural Characterization and Catalytic Activity towards Cyclohexane Oxidation.

    Science.gov (United States)

    Sutradhar, Manas; Alegria, Elisabete C B A; Guedes da Silva, M Fátima C; Martins, Luísa M D R S; Pombeiro, Armando J L

    2016-03-29

    The reaction of the Schiff base (3,5-di-tert-butyl-2-hydroxybenzylidene)-2-hydroxybenzohydrazide (H3L) with a copper(II) salt of a base of a strong acid, i.e., nitrate, chloride or sulphate, yielded the mononuclear complexes [Cu(H2L)(NO3)(H2O)] (1), [Cu(H2L)Cl]·2MeOH (2) and the binuclear complex [{Cu(H2L)}2(µ-SO4)]·2MeOH (3), respectively, with H2L(-) in the keto form. Compounds 1-3 were characterized by elemental analysis, Infrared (IR) spectroscopy, Electrospray Ionisation Mass Spectrometry (ESI-MS) and single crystal X-ray crystallography. All compounds act as efficient catalysts towards the peroxidative oxidation of cyclohexane to cyclohexyl hydroperoxide, cyclohexanol and cyclohexanone, under mild conditions. In the presence of an acid promoter, overall yields (based on the alkane) up to 25% and a turnover number (TON) of 250 (TOF of 42 h(-1)) after 6 h, were achieved.

  19. Copper (II) complexes possessing alkyl-substituted polypyridyl ligands: Structural characterization and in vitro antitumor activity.

    Science.gov (United States)

    Angel, Noah R; Khatib, Raneen M; Jenkins, Julia; Smith, Michelle; Rubalcava, Justin M; Le, Brian Khoa; Lussier, Daniel; Chen, Zhuo Georgia; Tham, Fook S; Wilson, Emma H; Eichler, Jack F

    2017-01-01

    In an effort to find alternatives to the antitumor drug cisplatin, a series of copper (II) complexes possessing alkyl-substituted polypyridyl ligands have been synthesized. Eight new complexes are reported herein: μ-dichloro-bis{2,9-di-sec-butyl-1,10-phenanthrolinechlorocopper(II)} {[((di-sec-butyl)phen)ClCu(μ-Cl)2CuCl((di-sec-butyl)phen)]}(1), 2-sec-butyl-1,10-phenanthrolinedichlorocopper(II) {([mono-sec-butyl)phen) CuCl2} (2), 2,9-di-n-butyl-1,10-phenanthrolinedichlorocopper(II) {[(di-n-butyl)phen) CuCl2}(3), 2-n-butyl-1,10-phenanthrolinedichlorocopper(II) {[(mono-n-butyl)phen) CuCl2} (4), 2,9-di-methyl-1,10-phenanthrolineaquadichlorocopper(II) {[(di-methyl)phen) Cu(H2O)Cl2}(5), μ-dichloro-bis{6-sec-butyl-2,2'-bipyridinedichlorocopper(II)} {((mono-sec-butyl)bipy) ClCu(μ-Cl)2CuCl((mono-sec-butyl)bipy)} (6), 6,6'-di-methyl-2,2'-bipyridinedichlorocopper(II) {(6,6'-di-methyl)bipy) CuCl2} (7), and 4,4'-dimethyl-2,2'-bipyridinedichlorocopper(II) {(4,4'-di-methyl)bipy) CuCl2} (8). These complexes have been characterized via elemental analysis, UV-vis spectroscopy, and mass spectrometry. Single crystal X-ray diffraction experiments revealed the complexes synthesized with the (di-sec-butyl)phen ligand (1) and (mono-sec-butyl)bipy ligand (6) crystallized as dimers in which two copper(II) centers are bridged by two chloride ligands. Conversely, complexes 2, 7, and 8 were isolated as monomeric species possessing distorted tetrahedral geometries, and the [((di-methyl)phen)Cu(H2O)Cl2] (5) complex was isolated as a distorted square pyramidal monomer possessing a coordinating aqua ligand. Compounds 1-8 were evaluated for their in vitro antitumor efficacy. Compounds 1, 5, and 7 in particular were found to exhibit remarkable activity against human derived lung cancer cells, yet this class of copper(II) compounds had minimal cytotoxic effect on non-cancerous cells. In vitro control experiments indicate the activity of the copper(II) complexes most likely does not arise from the

  20. Structural and spectroscopic characterization of five coordinate iron and cobalt bis(dithiolene)-trimethylphosphine complexes

    Science.gov (United States)

    Selby-Karney, Troy; Grossie, David A.; Arumugam, Kuppuswamy; Wright, Eyglo; Chandrasekaran, P.

    2017-08-01

    Heteroleptic bis(dithiolene)-phosphine iron and cobalt complexes [Fe(adt)2(PMe3)] (1) and [Co(adt)2(PMe3)] (2) (adt = para-anisyldithiolene) have been synthesized from corresponding bis(dithiolene) dimers [M2(adt)4]2 (M = Fe, Co) by reacting with excess PMe3 in dichloromethane. Solid-state structures of 1 and 2 have been determined by single crystal X-ray crystallography, and the dithiolene ligands Csbnd S (≈1.72 Å) and Csbnd C (≈1.37 Å) bond distances reveal the coordination of π-radical monoanionic dithiolene (adt•1-) ligands to metal centers. Intense low energy ligand-to-ligand-charge transfer (LLCT) absorption band (743 nm for 1; 905 nm for 2) in UV-vis spectra and characteristic ν(Cdbnd S•) (1168 cm-1 for 1; 1170 cm-1 for 2) in IR spectra affirms coordination of π-radical monoanionic dithiolenes to divalent metal ions. The cyclic voltammogram of 1 and 2 shows reversible oxidation and reduction waves attributed to MII → MIII + e- (+0.52 V for 1; +0.29 V for 2) and adt•1- + e- → adt2- (-0.63 V for 1; -0.46 V for 2) redox process respectively. Comprehensive structural and spectroscopic investigations conclude, [M2III(adt2-)2(adt•1-)2] → 2 [MII(adt•1-)2(PMe3)] intramolecular redox interplay during phosphine coordination induced cleavage of homoleptic bis(dithiolene) dimers to produce square pyramidal complexes.

  1. cis-Dioxomolybdenum(VI) complexes of a new ONN chelating thiosemicarbazidato ligand; Synthesis, characterization, crystal, molecular structures and antioxidant activities

    Science.gov (United States)

    İlhan Ceylan, Berat; Deniz, Nahide Gulsah; Kahraman, Sibel; Ulkuseven, Bahri

    2015-04-01

    5-Chloro-4-methyl-2-hydroxybenzophenone S-propyl-4-phenyl-thiosemicarbazone (H2L) and its cis-dioxomolybdenum(VI) complexes, in the general formula [MoO2(L)R-OH)] (R: methyl, 1; ethyl, 2; n-propyl, 3; n-butyl, 4; n-pentyl, 5), were synthesized and characterized by micro analysis, electronic, infrared and 1H and 13C NMR spectra. The crystal structures of complexes, 1 and 3, have been solved by direct methods (SIR92) and refined to the residual indexes R1 = 0.098 and R1 = 0.052 respectively. Complexes 1 and 3 are crystallized in the triclinic space group P-1 with Z = 2. The crystal study of complex 1 showed the first example of intermolecular hydrogen bond for this type of molybdenum-thiosemicarbazone complexes. The hydrogen bond is between the hydroxyl proton of attached alcohol and an oxo oxygen (in MoO22+ unit) of another complex molecule, and its bond distance (1.767(1) Å) is shorter than from the σ-coordination bonds in complex 1. Antioxidant activities of the compounds were determined by using 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. Ligand showed 23.61% DPPH radical scavenging activity at 250 mg/L concentration. Cupric Reducing Antioxidant Capacity (CUPRAC) was also evaluated and trolox-equivalent antioxidant capacity (TEAC) values were found for ligand, 1 and 3 as 0.51, 0.33 and 0.30 respectively.

  2. Rockfall source characterization at high rock walls in complex geological settings by photogrammetry, structural analysis and DFN techniques

    Science.gov (United States)

    Agliardi, Federico; Riva, Federico; Galletti, Laura; Zanchi, Andrea; Crosta, Giovanni B.

    2016-04-01

    Rockfall quantitative risk analysis in areas impended by high, subvertical cliffs remains a challenge, due to the difficult definition of potential rockfall sources, event magnitude scenarios and related probabilities. For this reasons, rockfall analyses traditionally focus on modelling the runout component of rockfall processes, whereas rock-fall source identification, mapping and characterization (block size distribution and susceptibility) are over-simplified in most practical applications, especially when structurally complex rock masses are involved. We integrated field and remote survey and rock mass modelling techniques to characterize rock masses and detect rockfall source in complex geo-structural settings. We focused on a test site located at Valmadrera, near Lecco (Southern Alps, Italy), where cliffs up to 600 m high impend on a narrow strip of Lake Como shore. The massive carbonates forming the cliff (Dolomia Principale Fm), normally characterized by brittle structural associations due to their high strength and stiffness, are here involved in an ENE-trending, S-verging kilometre-scale syncline. Brittle mechanisms associated to folding strongly controlled the nature of discontinuities (bedding slip, strike-slip faults, tensile fractures) and their attributes (spacing and size), as well as the spatial variability of bedding attitude and fracture intensity, with individual block sizes up to 15 m3. We carried out a high-resolution terrestrial photogrammetric survey from distances ranging from 1500 m (11 camera stations from the opposite lake shore, 265 pictures) to 150 m (28 camera stations along N-S directed boat routes, 200 pictures), using RTK GNSS measurements for camera station geo-referencing. Data processing by Structure-from-Motion techniques resulted in detailed long-range (1500 m) and medium-range (150 to 800 m) point clouds covering the entire slope with maximum surface point densities exceeding 50 pts/m2. Point clouds allowed a detailed

  3. Mononuclear mercury(II) complexes containing bipyridine derivatives and thiocyanate ligands: Synthesis, characterization, crystal structure determination, and luminescent properties

    Science.gov (United States)

    Amani, Vahid; Alizadeh, Robabeh; Alavije, Hanieh Soleimani; Heydari, Samira Fadaei; Abafat, Marzieh

    2017-08-01

    A series of mercury(II) complexes, [Hg(Nsbnd N)(SCN)2] (Nsbnd N is 4,4‧-dimethyl-2,2‧-bipyridine in 1, 5,5‧-dimethyl-2,2‧-bipyridine in 2, 6,6‧-dimethyl-2,2‧-bipyridine in 3 and 6-methyl-2,2‧-bipyridine in 4), were prepared from the reactions of Hg(SCN)2 with mentioned ligands in methanol. Suitable crystals of these complexes were obtained for X-ray diffraction measurement by methanol diffusion into a DMSO solution. The four complexes were thoroughly characterized by spectral methods (IR, UV-Vis, 13C{1H}NMR, 1H NMR and luminescence), elemental analysis (CHNS) and single crystal X-ray diffraction. The X-ray structural analysis indicated that in the structures of these complexes, the mercury(II) cation is four-coordinated in a distorted tetrahedral configuration by two S atoms from two thiocyanate anions and two N atoms from one chelating 2,2‧-bipyridine derivative ligand. Also, in these complexes intermolecular interactions, for example Csbnd H⋯N hydrogen bonds (in 1-4), Csbnd H⋯S hydrogen bonds (in 1, 2 and 4), π … π interactions (in 2-4), Hg⋯N interactions (in 2) and S⋯S interactions (in 4), are effective in the stabilization of the crystal structures and the formation of the 3D supramolecular complexes. Furthermore, the luminescence spectra of the title complexes show that the intensity of their emission bands are stronger than the emission bands for the free bipyridine derivative ligands.

  4. Transition metal complexes with pyrazole based ligands. Part 27. Structural and thermal characterization of cobalt(II halide and pseudohalide complexes with 4-acetyl-3-amino-5-methylpyrazole

    Directory of Open Access Journals (Sweden)

    VUKADIN M. LEOVAC

    2007-12-01

    Full Text Available The crystal and molecular structures of four tetrahedral structurally similar [Co(aamp2X2] complexes (aamp = 4-acetyl-3-amino-5-methylpyrazole, X = Cl, Br, I and NCS were determined by X-ray diffraction analysis and are discussed in detail. It was found that the different capacity of the ligand X (NCS vs. Cl, Br, I for the formation of non-bonding cntacts influence the mode of molecular association in the solid state. The complexes were characterized by UV–Vis spectroscopy. The first step of the thermal decomposition of the compounds was checked and is discussed in the view of the IR spectrum of the intermediate isolated from [Co(aamp2Br2] by the quasi-isothermal technique.

  5. Adsorptive characterization of the ZIF-68 metal-organic framework: a complex structure with amphiphilic properties.

    Science.gov (United States)

    Van der Perre, Stijn; Van Assche, Tom; Bozbiyik, Belgin; Lannoeye, Jeroen; De Vos, Dirk E; Baron, Gino V; Denayer, Joeri F M

    2014-07-22

    In this experimental study, the adsorption behavior of the ZIF-68 heterolinked zeolitic imidazolate framework has been explored. Vapor phase adsorption isotherms of linear C1-C6 alcohols, C6 alkane isomers, aromatics (benzene, toluene, xylene isomers, 1,3,5-trimethylbenzene, and 1,3,5-triisopropylbenzene), and polar adsorbates (water, acetonitrile, and acetone) are reported and discussed. The complex pore structure of ZIF-68, with two one-dimensional channels, each with a different polarity, displays an overall hydrophobic character. Its two-pore system results in S-shaped isotherms for small polar adsorbates (small alcohols, acetone, and acetonitrile), while longer alcohols and nonpolar molecules, such as aromatics and C6 alkane isomers, lead to type I adsorption isotherms. Bulky molecules, with a kinetic diameter significantly larger than the pore windows, are adsorbed in large amounts, which gave reason to think that this ZIF-68 material has a certain degree of framework flexibility to enlarge the free aperture of the channels. Besides, diffusion coefficients from vapor phase uptake and infrared experiments point to a different adsorption mechanism for polar and nonpolar adsorbates. Liquid phase adsorption experiments demonstrated the separation of alcohol mixtures (ethanol/1-butanol) at low concentration from water, with a clear preference for 1-butanol.

  6. Synthesis, Crystal Structure, and Characterization of Ternary Copper(II Complex Derived from N-(salicylidene-L-valine

    Directory of Open Access Journals (Sweden)

    Sundaramurthy Santha Lakshmi

    2016-01-01

    Full Text Available Ternary Schiff base copper(II complex [CuL(tmpda] (where H2L is N-(salicylidene-L-valine; tmpda is N,N,N′,N′-tetramethyl-1,3-propanediamine has been characterized by UV-Vis., FTIR, and single crystal XRD. The crystal structure displays a distorted square pyramidal geometry in which Schiff base is bonded to the Cu(II ion via phenolate oxygen, imine nitrogen, and an oxygen atom of the carboxylate group through the basal plane and the chelating diamine, N,N,N′,N′-tetramethyl-1,3-propanediamine, displays an axial and equatorial mode of binding via NN-donor atoms.

  7. Synthesis and structural characterization of new oxovanadium(IV) complexes derived from azo-5-pyrazolone with prospective medical importance

    Science.gov (United States)

    Bagdatli, Emine; Altuntas, Eylem; Sayin, Ulku

    2017-01-01

    Four novel o-hydroxy substituted aryl-(msbnd H, sbnd Cl, sbnd Br, sbnd CH3) azo-5-pyrazolone compounds (2a-d, respectively) were synthesized as azo-group containing ligands by diazotization of aryl amines then coupled with 1-(4-chlorophenyl)-3-isopropyl-1H-pyrazol-5(4H)-one (1) and the structures were confirmed by FTIR, UV-Visible, GC-MS or ESI-LCMS and NMR spectroscopic techniques. As a result, the first synthesis of azo-5-pyrazolone based oxovanadium(IV) complexes (3a-d) was achieved by interaction of 2a-d with half equivalent of vanadyl sulphate pentahydrate in a methanolic medium with moderate to high yields (67, 74, 60, 71 for 3a-d, respectively). The resulting complexes were characterized using FTIR, UV-Visible, ESI-LCMS and EPR spectroscopic techniques as well as with thermogravimetric (TG/DTG) analysis. They have the composition [VO(L)2]·H2O; (3a-c) or [VO(L)2]·CH3OH; (3d) where LH is an azo-5-pyrazolone compound as the ligand (2a-d). The electronic spectra of the complexes are typical of oxovanadium(IV) complexes showing a low intensity band near 500 nm. Spectroscopic results have shown that azo-5-pyrazolone compounds have acted bidendate and the coordination sites are hydroxyl-substituent on the -azo phenyl-aromatic ring and the pyrazolone carbonyl-moiety. The thermal data confirm that the complexes have methanol (3a-c) or water (3d) molecule outside the coordination sphere and the complexes show similar thermogravimetric decomposition fragments which are consistent with the proposed structures. A distorted octahedral geometry has been proposed for these complexes mainly with EPR and the other spectral techniques.

  8. Robust estimation of fractal measures for characterizing the structural complexity of the human brain: optimization and reproducibility.

    Science.gov (United States)

    Goñi, Joaquín; Sporns, Olaf; Cheng, Hu; Aznárez-Sanado, Maite; Wang, Yang; Josa, Santiago; Arrondo, Gonzalo; Mathews, Vincent P; Hummer, Tom A; Kronenberger, William G; Avena-Koenigsberger, Andrea; Saykin, Andrew J; Pastor, María A

    2013-12-01

    High-resolution isotropic three-dimensional reconstructions of human brain gray and white matter structures can be characterized to quantify aspects of their shape, volume and topological complexity. In particular, methods based on fractal analysis have been applied in neuroimaging studies to quantify the structural complexity of the brain in both healthy and impaired conditions. The usefulness of such measures for characterizing individual differences in brain structure critically depends on their within-subject reproducibility in order to allow the robust detection of between-subject differences. This study analyzes key analytic parameters of three fractal-based methods that rely on the box-counting algorithm with the aim to maximize within-subject reproducibility of the fractal characterizations of different brain objects, including the pial surface, the cortical ribbon volume, the white matter volume and the gray matter/white matter boundary. Two separate datasets originating from different imaging centers were analyzed, comprising 50 subjects with three and 24 subjects with four successive scanning sessions per subject, respectively. The reproducibility of fractal measures was statistically assessed by computing their intra-class correlations. Results reveal differences between different fractal estimators and allow the identification of several parameters that are critical for high reproducibility. Highest reproducibility with intra-class correlations in the range of 0.9-0.95 is achieved with the correlation dimension. Further analyses of the fractal dimensions of parcellated cortical and subcortical gray matter regions suggest robustly estimated and region-specific patterns of individual variability. These results are valuable for defining appropriate parameter configurations when studying changes in fractal descriptors of human brain structure, for instance in studies of neurological diseases that do not allow repeated measurements or for disease

  9. Synthesis, spectroscopic characterization, structural studies and antibacterial and antitumor activities of diorganotin complexes with 3-methoxysalicylaldehyde thiosemicarbazone

    Science.gov (United States)

    Khandani, Marzieh; Sedaghat, Tahereh; Erfani, Nasrollah; Haghshenas, Mohammad Reza; Khavasi, Hamid Reza

    2013-04-01

    Three organotin(IV) complexes, Ph2Sn(mstsc) (1), Me2Sn(mstsc) (2) and Bu2Sn(mstsc) (3), have been synthesized from reaction of R2SnCl2 (R = Ph, Me and Bu) with 3-methoxysalicylaldehyde thiosemicarbazone (H2mstsc). The synthesized complexes have been characterized by elemental analysis and FT-IR, 1H, 13C and 119Sn NMR spectroscopy. The structures of 2 and 3 have been also confirmed by X-ray crystallography. On the basis of spectral and structural data thiosemicarbazone acts as a tridentate dianionic ligand and coordinates to tin through phenolic oxygen, the azomethine nitrogen and thiolate sulfur atoms. The metal coordination geometry for 2 and 3 is described as distorted square pyramid and the crystal lattices are stabilized by intermolecular hydrogen bands. On the basis of 119Sn NMR data, coordination number of tin retains five in solution. The in vitro antibacterial activity of ligand and its complexes has been evaluated against one Gram-positive and three Gram-negative bacteria. Complex 2 exhibited good activity along with the standard antibacterial drugs. The in vitro cytotoxicities of the synthesized compounds against Jurkat cells were evaluated by the standard WST-1 assay. The activity decreases in the order 3 > 1 > 2 = H2mstsc.

  10. Organonickel(II) complexes with anionic tridentate 1, 3-bis(azolylmethyl)phenyl ligands. synthesis, structural characterization and catalytic behavior

    Energy Technology Data Exchange (ETDEWEB)

    Hurtado, John; Rojas, Rene; Valderrama, Mauricio, E-mail: jmvalder@puc.cl [Departamento de Quimica Inorganica, Facultad de Quimica, Pontificia Universidad Catolica de Chile, Santiago (Chile); Ibanez, Andres [Centro para la Investigacion Interdisciplinaria Avanzada en Ciencia de los Materiales (CIMAT), Santiago (Chile); Froehlich, Roland [Organisch Chemisches Institut der Universitaet Muenster, Muenster (Germany)

    2011-09-15

    The reaction of 2-bromo-1,3-bis(bromomethyl)benzene with 3,5-dimethylpyrazole and {sup 1}H-indazole yields the tridentate ligands 2-bromo-1,3-bis(3,5-dimethylpirazol-1-ylmethyl)benzene (1) and 2-bromo-1,3-bis(indazol-2-ylmethyl)benzene (2). These compounds react with [Ni(cod)2] in tetrahydrofuran (thf) to form the oxidative addition complexes [NiBr{l_brace}1,3-bis(azolylmethyl)phenyl-N,C,N{r_brace}], azol 3,5-dimethylpyrazol (3), indazol (4), which were isolated in good yields as stable yellow solids and characterized by elemental analysis, Fourier-transform infrared spectroscopy (FTIR), mass spectroscopy and nuclear magnetic resonance (NMR). In addition, the molecular structures of 2 and 4 were determined by single-crystal X-ray diffraction analysis. Complex 4 was tested as a catalyst in ethylene polymerization reaction. (author)

  11. Structural characterization of Am(III) formate complexes. Combining EXAFS spectroscopy with DFT and thermodynamical calculations

    Energy Technology Data Exchange (ETDEWEB)

    Rossberg, Andre [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Molecular Structures; Froehlich, D.R. [Heidelberg Univ. (Germany). Physikalisch-Chemisches Inst.

    2017-06-01

    We used iterative transformation factor analysis (ITFA) in order to isolate the EXAFS spectral contributions of the complexing ligand from a Am(III)/formate pH-series. Thermodynamic calculations were used as constraint for ITFA and for density functional theory (DFT) calculations to identify the coordination mode within the formed complexes.

  12. Synthesis, structure, and characterization of new mononuclear Mn(II) complexes. Electrochemical conversion into new oxo-bridged Mn(2)(III,IV) complexes. Role of chloride ions.

    Science.gov (United States)

    Hureau, Christelle; Blondin, Geneviève; Charlot, Marie-France; Philouze, Christian; Nierlich, Martine; Césario, Michèle; Anxolabéhère-Mallart, Elodie

    2005-05-16

    Two Mn(II) complexes are isolated and X-ray characterized, namely, cis-[(L(2))Mn(II)(Cl)(2)] (1) and [(L(3))Mn(II)Cl(OH(2))](ClO(4)) (2(ClO(4))), where L(2) and L(3) are the well-known tetradentate N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)ethane-1,2-diamine and N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)propane-1,3-diamine ligands, respectively. The crystal structure reveals that whereas the ligand L(2) is in the cis-alpha conformation in complex 1, the ligand L(3) is in the more unusual cis-beta conformation in 2. EPR spectra are recorded on frozen solutions for both complexes and are characteristic of Mn(II) species. Electrochemical behaviors are investigated on acetonitrile solution for both complexes and show that cation 2 exists as closely related Mn(II) species in equilibrium. For both complexes exhaustive bulk electrolyses of acetonitrile solution are performed at oxidative potential in various experimental conditions. In the presence of 2,6-lutidine and after elimination of chloride ligands, the formation of the di-mu-oxo mixed-valent complexes [(L(2))Mn(III)(mu-O)(2)Mn(IV)(L(2))](3+) (3a) and [(L(3))Mn(III)(mu-O)(2)Mn(IV)(L(3))](3+) (4) is confirmed by UV-vis and EPR spectroscopies and cyclic voltammetry. In addition crystals of 4(ClO(4))(3) were isolated, and the X-ray structure reveals the cis-alphaconformation of L(3). In the absence of 2,6-lutidine and without elimination of the exogenous chloride ions, the electrochemical oxidation of 1 leads to the formation of the mononuclear Mn(III) complex, namely, [(L(2))Mn(III)(Cl)(2)](+) (5), as confirmed by UV-vis as well as parallel mode EPR spectroscopy and cyclic voltammetry. In the same conditions, the electrochemical oxidation of complex 2 is more intricate, and a thorough analysis of EPR spectra establishes the formation of the binuclear mono-mu-oxo mixed-valent [(L(3))ClMn(III)(mu-O)Mn(IV)Cl(L(3))](3+) (6) complexes. Electrochemical conversion of Mn(II) complexes into mixed-valent Mn(2)(III,IV) oxo

  13. Structural and functional characterization of the yeast Ski2-Ski3-Ski8 complex

    OpenAIRE

    Halbach, Felix

    2013-01-01

    The Ski2-Ski3-Ski8 (SKI) complex is a conserved multi-protein assembly required for the cytoplasmic functions of the exosome, including messenger RNA (mRNA) turnover, surveillance and interference. The helicase Ski2, the tetratricopeptide repeat (TPR) protein Ski3 and the �-propeller Ski8 assemble in a heterotetramer with 1:1:2 stoichiometry. While the function of the Ski2-Ski3-Ski8 complex as a general cofactor of the cytoplasmic exosome has been well established, it remains largely uncle...

  14. Synthesis, characterization and crystal structure of a 2-(diethylaminomethylindole ligated dimethylaluminium complex

    Directory of Open Access Journals (Sweden)

    Logan E. Shephard

    2015-10-01

    Full Text Available The title compound, [Al(CH32(C13H17N2] (systematic name; {2-[(diethylaminomethyl]indol-1-yl-κ2N,N′}dimethylaluminium, was prepared by methane elimination from the reaction of 2-(diethylaminomethylindole and trimethylaluminium. The complex crystallizes readily from a concentrated toluene solution in high yield. The asymmetric unit contains two crystallographically independent molecules. Each molecule has a four-coordinate aluminium atom that has pseudo-tetrahedral geometry. C—H...π interactions link the independent molecules into chains extending along the b-axis direction.

  15. Synthesis, characterization, electronic structure and catalytic activity of new ruthenium carbonyl complexes of N-[(2-pyridyl)methylidene]-2-aminothiazole

    Science.gov (United States)

    Kundu, Subhankar; Sarkar, Deblina; Jana, Mahendra Sekhar; Pramanik, Ajoy Kumar; Jana, Subrata; Mondal, Tapan Kumar

    2013-03-01

    Reaction of ruthenium carbonyls, [Ru(CO)2Cl2]n/[Ru(CO)4I2] with bidentate Schiffs base ligands derived by the condensation of pyridine-2-carboxaldehyde with 2-aminothiazole in a 1:1 mole ratio in acetonitrile led to the formation of complexes having general formula [Ru(CO)2(L)X2] (X = Cl (1) and I (2)) (L = N-[(2-pyridyl)methylidene]-2-aminothiazole). The compounds have been characterized by various analytical and spectroscopic (IR, electronic and 1H NMR) studies. In acetonitrile solution the complexes exhibit a weak broad metal-ligand to ligand charge transfer (MLLCT) band along with ILCT transitions. The compounds are emissive in room temperature upon excitation in the ILCT band. The complexes exhibit a quasi-reversible one electron Ru(II)/Ru(III) oxidation couple at 1.44 V for 1 and 0.94 V for 2. Catalytic activity of these compounds is investigated to the oxidation of PhCH2OH to PhCHO, 2-butanol (C4H9OH) to 2-butanone, 1-phenylethanol (PhC2H4OH) to acetophenone, cyclopentanol (C5H9OH) to cyclopentanone, cyclohexanol to cyclohexanone, cycloheptanol to cycloheptanone and cycloctanol to cycloctanone using N-methylmorpholine-N-oxide (NMO) as oxidant. The catalytic efficiency of 2 is greater than complex 1 and well correlate with the metal oxidation potential of the complexes. DFT, NBO and TDDFT calculations are employed to explain the structural and electronic features and to support the spectroscopic assignments.

  16. Luminescent alkynyl platinum-cadmium complexes: structural characterization of an unusual decanuclear cluster.

    Science.gov (United States)

    Forniés, J; Gómez, J; Lalinde, E; Moreno, M T

    2001-10-08

    The reaction of (NBu(4))(2)[Pt(C triple bond CPh)(4)] with Cd(ClO(4))(2).6H(2)O in a 1:1 molar ratio yields a white solid [PtCd(C triple bond CPh)(4)](n) 1 (75% yield) together with yellow crystals of a very unusual decanuclear platinum-cadmium cluster [Pt(4)Cd(6)(C triple bond CPh)(4)(mu-C triple bond CPh)(12)(mu(3)-OH)(4)] 2 in low yield. Slow diffusion of acetonic solutions of the starting materials under aerobic conditions only produces crystals of 2 which have been shown by an X-ray analysis to be composed of a big hexanuclear cation [Cd(6)(mu(3)-OH)(4)](8+) and four [Pt(C triple bond CPh)(4)](2-) anions, held together by Pt.Cd and pi.Cd acetylide interactions. On the other hand, treatment of the insoluble product 1 with 1 equiv of NBu(4)X yields tetranuclear mixed-metal soluble complexes (NBu(4))(2)[[Pt(mu-C triple bond CPh)(4)](2)(CdX)(2)] (X = Cl A, Br 3, CN 4), which contain two platinate fragments connected by two CdX units through Pt.Cd and mainly Cd.C(alpha) interactions. All complexes are strongly emissive in the solid state at room temperature.

  17. SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF A NOVEL Mg(II COMPLEX WITH 1,2-PHENYLENEDIOXYDIACETIC ACID

    Directory of Open Access Journals (Sweden)

    XI-SHI TAI

    2014-11-01

    Full Text Available A novel Mg(II complex, [Mg(HL2•(H2O4]•4H2O•HCl (HL = 1,2-phenylenedioxydiacetato, has been synthesized by the reaction of 1,2-phenylenedioxydiacetic acid, NaOH and MgCl2•6H2O in one-pot. The compound was characterized by X-ray single crystal diffraction analysis. The crystal of the title complex belongs to monoclinic, space group Pn with a = 10.772(2 Å, b = 9.7145(19 Å, c = 13.996(3 Å, β = 104.32(3º, V = 1419.1(5 Å3, Z = 2, Dc = 1.498 μg•m-3, μ = 0.245 mm-1, F(000 = 658 and final R1 = 0.0653, ωR2 = 0.1913. The molecules are connected by π-π stacking to form three dimensional network structures.

  18. Structural and dynamical characterization of the pH-dependence of the pectin methylesterase-pectin methylesterase inhibitor complex.

    Science.gov (United States)

    Sénéchal, Fabien; Habrylo, Olivier; Hocq, Ludivine; Domon, Jean-Marc; Marcelo, Paulo; Lefebvre, Valérie; Pelloux, Jérôme; Mercadante, Davide

    2017-12-29

    Pectin methylesterases (PMEs) catalyze the demethylesterification of pectin, one of the main polysaccharides in the plant cell wall, and are of critical importance in plant development. PME activity generates highly negatively charged pectin and mutates the physiochemical properties of the plant cell wall such that remodeling of the plant cell can occur. PMEs are therefore tightly regulated by proteinaceous inhibitors (PMEIs), some of which become active upon changes in cellular pH. Nevertheless, a detailed picture of how this pH-dependent inhibition of PME occurs at the molecular level is missing. Herein, using an interdisciplinary approach that included homology modeling, MD simulations, and biophysical and biochemical characterizations, we investigated the molecular basis of PME3 inhibition by PMEI7 in Arabidopsis thaliana Our complementary approach uncovered how changes in the protonation of amino acids at the complex interface shift the network of interacting residues between intermolecular and intramolecular. These shifts ultimately regulate the stability of the PME3-PMEI7 complex and the inhibition of the PME as a function of the pH. These findings suggest a general model of how pH-dependent proteinaceous inhibitors function. Moreover, they enhance our understanding of how PMEs may be regulated by pH and provide new insights into how this regulation may control the physical properties and structure of the plant cell wall. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  19. Gold(III) bis-thiosemicarbazonato complexes: synthesis, characterization, radiochemistry and X-ray crystal structure analysis.

    Science.gov (United States)

    Bottenus, Brienne N; Kan, Para; Jenkins, Tyler; Ballard, Beau; Rold, Tammy L; Barnes, Charles; Cutler, Cathy; Hoffman, Timothy J; Green, Mark A; Jurisson, Silvia S

    2010-01-01

    A variety of (bis)thiosemicarbazone-based ligand systems have been investigated as chelating agents for Au(III) complexes with potential radiotherapeutic applications. Ligand systems containing an ethyl, propyl or butyl backbone between the two imine N donors have been synthesized to evaluate chelate ring size effects on the resultant Au(III) complex stability at the macroscopic and radiotracer levels. The Au(III) complexes were synthesized and characterized by NMR, electrospray ionization mass spectra, elemental analysis and X-ray crystallography. The (198)Au complexes were evaluated in vitro at the tracer level for stability in phosphate-buffered saline at pH 7.4 and 37 degrees C. One of these complexes [(198)Au(3,4-HxTSE)] showed high in vitro stability and was further evaluated in vivo in normal mice. [Au(ATSM)]AuCl(4).2CH(3)OH, (ATSM=diacetyl-bis(N(4)-methylthiosemicarbazone)) H(14)C(8)N(6)O(2)S(2)Cl(4)Au(2).2CH(3)OH, crystallized from methanol in the monoclinic space group P21/n with a=14.7293(13) A, b=7.7432(7) A, c=20.4363(18) A, beta=100.140(2) degrees, V=2294.4 (4) A(3), Z=4; [Au(3,4-HxTSE)]Cl.CH(3)CH(2)OH/AuCl(2), (3,4-HxTSE=3,4-hexanedione-bis(N(4)-ethylthiosemicarbazone)) H(26)C(13.6)N(6)O(0.8)S(2)Cl(1.2)Au(1.2), crystallized from ethanol in the monoclinic space group P21/c with a=10.1990(10) A, b=13.8833(14) A, c=15.1752(15) A, beta=99.353(2) degrees , V=2120.2 (4) A(3), Z=4. These studies revealed poor stability of the [(198)Au][Au(3,4-HxTSE)](+) complex; however, crystal structure data suggest potential alterations to the ligand backbone may increase stability. Copyright 2010 Elsevier Inc. All rights reserved.

  20. Modular fabrication and characterization of complex silicon carbide composite structures Advanced Reactor Technologies (ART) Research Final Report (Feb 2015 – May 2017)

    Energy Technology Data Exchange (ETDEWEB)

    Khalifa, Hesham [General Atomics, San Diego, CA (United States)

    2017-08-03

    Advanced ceramic materials exhibit properties that enable safety and fuel cycle efficiency improvements in advanced nuclear reactors. In order to fully exploit these desirable properties, new processing techniques are required to produce the complex geometries inherent to nuclear fuel assemblies and support structures. Through this project, the state of complex SiC-SiC composite fabrication for nuclear components has advanced significantly. New methods to produce complex SiC-SiC composite structures have been demonstrated in the form factors needed for in-core structural components in advanced high temperature nuclear reactors. Advanced characterization techniques have been employed to demonstrate that these complex SiC-SiC composite structures provide the strength, toughness and hermeticity required for service in harsh reactor conditions. The complex structures produced in this project represent a significant step forward in leveraging the excellent high temperature strength, resistance to neutron induced damage, and low neutron cross section of silicon carbide in nuclear applications.

  1. Synthesis, structural characterization, Hirshfeld surface analysis and spectroscopic studies of cadmium (II) chloride complex with 4-hydroxy-1-methylpiperidine

    Energy Technology Data Exchange (ETDEWEB)

    Soudani, S. [Université de Carthage, Laboratoire de Chimie des Matériaux, Faculté des Sciences de Bizerte, 7021 Zarzouna (Tunisia); Ferretti, V. [Department of Chemical and Pharmaceutical Sciences and Center for Structural Diffractometry, via Fossato di Mortara 17, I-44121 Ferrara (Italy); Jelsch, C. [CRM2, CNRS, Institut Jean Barriol, Université de Lorraine, Vandoeuvre les Nancy CEDEX (France); Lefebvre, F. [Laboratoire de Chimie Organométallique de Surface (LCOMS), Ecole Supérieure de Chimie Physique Electronique, 69626 Villeurbanne Cedex (France); Nasr, C. Ben, E-mail: cherif_bennasr@yahoo.fr [Université de Carthage, Laboratoire de Chimie des Matériaux, Faculté des Sciences de Bizerte, 7021 Zarzouna (Tunisia)

    2016-05-15

    The chemical preparation, crystal structure, Hirshfeld surface analysis and spectroscopic characterization of the novel cadmium (II) 4-hydroxy-1-methylpiperidine complex, Cd{sub 4}Cl{sub 10}(C{sub 6}H{sub 14}NO){sub 2}·2H{sub 2}O, have been reported. The atomic arrangement can be described as built up by an anionic framework, formed by edge sharing CdCl{sub 6} and CdCl{sub 5}O octahedral linear chains spreading along the a-axis. These chains are interconnected by water molecules via O–H⋯Cl and O–H⋯O hydrogen bonds to form layers parallel to (011) plane. The organic cations are inserted between layers through C–H⋯Cl hydrogen bonds. Investigation of intermolecular interactions and crystal packing via Hirshfeld surface analysis reveals that the H{sub C}⋯Cl and H{sub C}⋯H{sub C} intermolecular interactions are the most abundant contacts of the organic cation in the crystal packing. The statistical analysis of crystal contacts reveals the driving forces in the packing formation. The {sup 13}C and {sup 15}N CP-MAS NMR spectra are in agreement with the X-ray structure. The vibrational absorption bands were identified by infrared spectroscopy. DFT calculations allowed the attribution of the NMR peaks and of the IR bands.

  2. Synthesis, and structural characterization of mixed ligand copper(II) complexes of N,N,N‧,N'-tetramethylethylenediamine incorporating carboxylates

    Science.gov (United States)

    Batool, Syeda Shahzadi; Gilani, Syeda Rubina; Tahir, Muhammad Nawaz; Rüffer, Tobias

    2017-11-01

    Two ternary copper(II) complexes of N,N,N‧,N'-tetramethylethylenediamine (tmen = C6H16N2) with benzoic acid and p-aminobenzoic acid, having the formula [Cu(tmen)(BA)2(H2O)2] (1), and [Cu(tmen)(pABA)2]. 1/2 CH3OH (2) {(Where BA1- = benzoate1- (C6H5CO21-), pABA1- = p-aminobenzoate1- (p-H2NC6H5CO21-)} have been prepared and characterized by elemental combustion analysis, Uv-Visible spectroscopy, FT-IR spectroscopy, thermal, and single crystal X-ray diffraction analyses. The complex 1 is a monomer with distorted octahedral geometry. In its CuN2O4 chromophore, the Cu(II) centre is coordinated by two N atoms of a symmetrically chelating tmen ligand, by two carboxylate-O atoms from two monodentate benzoate1- anions, and by two apical aqua-O atoms, which define the distorted octahedral structure. The complex 2 is a monomer with a distorted square planar coordination geometry. In CuN2O2 chromophore, tmen is coordinated to Cu(II) ion in a chelating bidentate fashion, while the two p-aminobenzoate1- anions coordinate to Cu(II) centre through their carboxylate-O atoms in a monodentate manner, forming a square planar structure. The observed difference between asymmetric ѵas(OCO) and symmetric ѵs(OCO) stretching IR vibrations of the carboxylate moieties for 1 and 2 is 220 cm-1 and 232 cm-1, respectively, which suggests monodentate coordination mode (Δν OCO>200) of the carboxylate groups to Cu(II) ion. Thermogravimetric studies of 1 indicates removal of two water molecules at 171 °C, elimination of a tmen upto 529 °C and of two benzoate groups upto 931 °C. In tga curve of 2, methanol is lost upto 212 °C, while tmen is lost from 212 to 993 °C. The antibacterial activities of these new compounds against various bacterial strains were also investigated.

  3. Characterization of Injection Molded Structures

    DEFF Research Database (Denmark)

    Sun, Ling; Søgaard, Emil; Andersen, Nis Korsgaard

    and limitations. Therefore, it would be difficult to characterize complex, especially hierarchical structures by using only one method. Here we present a combined optical microscopy, scanning electron microscopy (SEM), and scanning probe microscopy study on injection molded structures. These structures are used......-properties relationship of the injection molded polymer samples. These results are very important in optimizing injection molding parameters....

  4. Structural and Catalytic Characterization of a Heterovalent Mn(II)Mn(III) Complex That Mimics Purple Acid Phosphatases

    OpenAIRE

    Smith, Sarah J.; Riley, Mark J.; Noble, Christopher J.; Hanson, Graeme R.; Stranger, Robert; Jayaratne, Vidura; Cavigliasso, German; Schenk,Gerhard; Gahan, Lawrence R

    2009-01-01

    The binuclear heterovalent manganese model complex [Mn(II)Mn(III)(L1)(OAc)2] ClO4 3 H2O (H2L1 = 2-(((3-((bis- (pyridin-2-ylmethyl)amino)methyl)-2-hydroxy-5-methylbenzyl)(pyridin-2-ylmethyl)amino)-methyl)phenol) has been prepared and studied structurally, spectroscopically, and computationally. The magnetic and electronic properties of the complex have been related to its structure. The complex is weakly antiferromagnetically coupled (J ∼ -5 cm-1, H =-2J S1 3 S2) and the electron p...

  5. Formation and structural characterization of a europium(II mono(scorpionate complex and a sterically crowded pyrazabole

    Directory of Open Access Journals (Sweden)

    Phil Liebing

    2017-12-01

    Full Text Available The reaction of EuI2(THF2 with potassium hydrotris(3,5-diisopropylpyrazolylborate (K[HB(3,5-iPr2pz3] (= KTpiPr2, pz = pyrazolyl in a molar ratio of 1:1.5 resulted in extensive ligand fragmentation and formation of the europium(II mono(scorpionate complex bis(3,5-diisopropyl-1H-pyrazole[hydrotris(3,5-diisopropylpyrazolylborato]iodidoeuropium(II, [Eu(C27H46BN6I(C9H16N22] or (TpiPr2(3,5-iPr2pzH2EuIII, 1, in high yield (78%. As a typical by-product, small amounts of the sterically crowded pyrazabole derivative trans-4,8-bis(3,5-diisopropylpyrazol-1-yl-1,3,5,7-tetraisopropylpyrazabole, C36H62B2H8 or trans-{(3,5-iPr2pzHB(μ-3,5-iPr2pz}2, 2, were formed. Both title compounds have been structurally characterized through single-crystal X-ray diffraction. In 1, two isopropyl groups are each disordered over two orientations with occupancy ratios of 0.574 (10:0.426 (10 and 0.719 (16:0.281 (16. In 2, one isopropyl group is similarly disordered, occupancy ratio 0.649 (9:0.351 (9.

  6. Structural characterization and electronic properties determination by high-field and high-frequency EPR of a series of five-coordinated Mn(II) complexes.

    Science.gov (United States)

    Mantel, Claire; Baffert, Carole; Romero, Isabel; Deronzier, Alain; Pécaut, Jacques; Collomb, Marie-Noëlle; Duboc, Carole

    2004-10-04

    The isolation, structural characterization, and electronic properties of a series of high-spin mononuclear five-coordinated Mn(II) complexes, [Mn(terpy)(X)(2)] (terpy = 2, 2':6',2' '-terpyridine; X = I(-) (1), Br(-) (2), Cl(-) (3), or SCN(-) (4)), are reported. The X-ray structures of the complexes reveal that the manganese ion lies in the center of a distorted trigonal bipyramid for complexes 1, 2, and 4, while complex 3 is better described as a distorted square pyramid. The electronic properties of 1-4 were investigated by high-field and high-frequency EPR spectroscopy (HF-EPR) performed between 5 and 30 K. The powder HF-EPR spectra have been recorded in high-field-limit conditions (95-285 GHz) (D EPR experiments, the sign of D was unambiguously determined. D is positive for the iodo and bromo complexes and negative for the chloro and thiocyano ones. A structural correlation is proposed. Each complex is characterized by a significant rhombicity with E/D values between 0.17 and 0.29, reflecting the distorted geometry observed around the manganese. Finally, we compared the spin Hamiltonian parameters of our five-coordinated complexes and those previously reported for other analogous series of dihalo four- and six-coordinated complexes. The effect of the coordination number and of the geometry of the Mn(II) complexes on the spin Hamiltonian parameters is discussed.

  7. Synthesis, structure characterization and biological activity of selected metal complexes of sulfonamide Schiff base as a primary ligand and some mixed ligand complexes with glycine as a secondary ligand

    Science.gov (United States)

    Sharaby, Carmen M.; Amine, Mona F.; Hamed, Asmaa A.

    2017-04-01

    The current work reports synthesis of metal complexes and mixed ligand complexes of a novel sulfonamide Schiff base ligand (HL) resulted from the condensation of sulfametrole [N‧-(4-methoxy-1,2,5-thiadiazol-3-yl]sulfanilamide and acetyl-acetone as a primary ligand and glycine as a secondary ligand. The metal complexes and mixed ligand complexes of HL Schiff base ligand were synthesized and characterized using different physicochemical studies as elemental analyses, mass spectra, conductivity measurement, IR spectra, 1H NMR spectra, UV-vis Spectra, solid reflectance, magnetic susceptibility, thermal analyses (TGA and DTA) and their microbial and anticancer activities. The spectroscopic data of the complexes suggest their 1:2(L1:M) complex structures and 1:2:2(L1:L2:M) mixed ligand complex structures, where L1 = HL and L2 = glycine. Also, the spectroscopic studies suggested the octahedral structure for all complexes. The synthesized Schiff base, its metal and mixed ligand complexes were screened for their bacterial, antifungal and anticancer activity. The activity data show that the metal complexes and mixed ligand complexes exhibited promising microbial and anticancer activities than their parent HL Schiff base ligand, also the data show that the mixed ligand complexes more effective than the metal complexes.

  8. Synthesis, characterization and structural studies of binuclear nickel(II complexes derived from dihydroxybenzaldehyde thiosemicarbazones, bridged by 1,2-bis(diphenylphosphinoethane

    Directory of Open Access Journals (Sweden)

    Hana B. Shawish

    2016-11-01

    Full Text Available The work described in this paper involves the synthesis and structural characterization of Ni(II complexes derived from dihydroxybenzaldehyde thiosemicarbazones (H3L1, H3L2, H3L3, H3L4 and 1,2-bis(diphenylphosphinoethane (dppe. Ligands and their Ni(II complexes were characterized by elemental analysis, IR, UV–Vis, (1H, 13C, 31P NMR, as well as magnetic moment and X-ray structure analysis. The results so obtained suggest that the thiosemicarbazone ligands behave as a tridentate ligand which were coordinated with Ni(II ion through O, N and S atoms. Furthermore, the dppe ligand was coordinated with Ni(II ion through the P atom. It is concluded that all Ni(II complexes have a Square-planar geometry.

  9. Structural and biochemical characterization of the inhibitor complexes of xenotropic murine leukemia virus-related virus protease

    Energy Technology Data Exchange (ETDEWEB)

    Li, Mi; Gustchina, Alla; Matúz, Krisztina; Tözsér, Jozsef; Namwong, Sirilak; Goldfarb, Nathan E.; Dunn, Ben M.; Wlodawer, Alexander (Debrecen); (NCI); (Florida); (Suan Sunandha)

    2012-10-23

    Interactions between the protease (PR) encoded by the xenotropic murine leukemia virus-related virus and a number of potential inhibitors have been investigated by biochemical and structural techniques. It was observed that several inhibitors used clinically against HIV PR exhibit nanomolar or even subnanomolar values of K{sub i}, depending on the exact experimental conditions. Both TL-3, a universal inhibitor of retroviral PRs, and some inhibitors originally shown to inhibit plasmepsins were also quite potent, whereas inhibition by pepstatin A was considerably weaker. Crystal structures of the complexes of xenotropic murine leukemia virus-related virus PR with TL-3, amprenavir and pepstatin A were solved at high resolution and compared with the structures of complexes of these inhibitors with other retropepsins. Whereas TL-3 and amprenavir bound in a predictable manner, spanning the substrate-binding site of the enzyme, two molecules of pepstatin A bound simultaneously in an unprecedented manner, leaving the catalytic water molecule in place.

  10. Thermal Analysis by Structural Characterization as a Method for Assessing Heterogeneity in Complex Solid Pharmaceutical Dosage Forms.

    Science.gov (United States)

    Alhijjaj, Muqdad; Reading, Mike; Belton, Peter; Qi, Sheng

    2015-11-03

    Characterizing inter- and intrasample heterogeneity of solid and semisolid pharmaceutical products is important both for rational design of dosage forms and subsequent quality control during manufacture; however, most pharmaceutical products are multicomponent formulations that are challenging in this regard. Thermal analysis, in particular differential scanning calorimetry, is commonly used to obtain structural information, such as degree of crystallinity, or identify the presence of a particular polymorph, but the results are an average over the whole sample; it cannot directly provide information about the spatial distribution of phases. This study demonstrates the use of a new thermo-optical technique, thermal analysis by structural characterization (TASC), that can provide spatially resolved information on thermal transitions by applying a novel algorithm to images acquired by hot stage microscopy. We determined that TASC can be a low cost, relatively rapid method of characterizing heterogeneity and other aspects of structure. In the examples studied, it was found that high heating rates enabled screening times of 3-5 min per sample. In addition, this study demonstrated the higher sensitivity of TASC for detecting the metastable form of polyethylene glycol (PEG) compared to conventional differential scanning calorimetry (DSC). This preliminary work suggests that TASC will be a worthwhile additional tool for characterizing a broad range of materials.

  11. Structural and spectroscopic characterization of DMF complexes with nitrogen, carbon dioxide, ammonia and water. Infrared matrix isolation and theoretical studies

    Science.gov (United States)

    Sałdyka, Magdalena; Mielke, Zofia; Haupa, Karolina

    2018-02-01

    An infrared spectroscopic and MP2/6-311++G(2d,2p) study of the complexes between N,N-dimethylformamide (DMF) and nitrogen, carbon dioxide, water, ammonia trapped in solid argon matrices is reported. The 1:1 molecular complexes have been identified in the DMF/B/Ar matrices (B = N2, CO, H2O, NH3); their structures were determined by comparison of the spectra with the results of calculations. The analysis of the experimental and theoretical data indicate that the DMF-N2, CO complexes present in the matrices are stabilized by (C=)O⋯N and (C=)O⋯C van der Waals interactions. In turn, in the DMF-H2O, NH3 complexes the (C=)O⋯H(OH) and (C=)O⋯H(NH2) hydrogen bonding is present in which the carbonyl group of DMF acts as a proton acceptor. In all systems studied the C-H⋯X (X = N, C, O) bonding is a second intermolecular force stabilizing the planar complexes. Some spectral features indicate that for DMF-H2O, DMF-NH3 systems the nonplanar structures with the C=O⋯H interaction are also present. The study demonstrated the strong sensitivity of the CH stretching wavenumber to an involvement of the C-H and/or C=O groups of DMF in an intermolecular interaction.

  12. Structural and catalytic characterization of a heterovalent Mn(II)Mn(III) complex that mimics purple acid phosphatases.

    Science.gov (United States)

    Smith, Sarah J; Riley, Mark J; Noble, Christopher J; Hanson, Graeme R; Stranger, Robert; Jayaratne, Vidura; Cavigliasso, Germán; Schenk, Gerhard; Gahan, Lawrence R

    2009-11-02

    The binuclear heterovalent manganese model complex [Mn(II)Mn(III)(L1)(OAc)(2)] ClO(4) x H(2)O (H(2)L1 = 2-(((3-((bis(pyridin-2-ylmethyl)amino)methyl)-2-hydroxy-5-methylbenzyl)(pyridin-2-ylmethyl)amino)-methyl)phenol) has been prepared and studied structurally, spectroscopically, and computationally. The magnetic and electronic properties of the complex have been related to its structure. The complex is weakly antiferromagnetically coupled (J approximately -5 cm(-1), H = -2J S(1) x S(2)) and the electron paramagnetic resonance (EPR) and magnetic circular dichroism (MCD) spectra identify the Jahn-Teller distortion of the Mn(III) center as predominantly a tetragonal compression, with a significant rhombic component. Electronic structure calculations using density functional theory have confirmed the conclusions derived from the experimental investigations. In contrast to isostructural M(II)Fe(III) complexes (M = Fe, Mn, Zn, Ni), the Mn(II)Mn(III) system is bifunctional possessing both catalase and hydrolase activities, and only one catalytically relevant pK(a) (= 8.2) is detected. Mechanistic implications are discussed.

  13. Synthesis, Characterization, and Structural Assessment of Ni(II Complexes Derived from Bis(2-hydroxy-1-naphthaldehydesuccinoyldihydrazone

    Directory of Open Access Journals (Sweden)

    Mithun Chakrabarty

    2015-01-01

    Full Text Available The monometallic nickel(II complexes [Ni(H2nsh(A2]·nH2O (where A = water (H2O, n=0 (1; pyridine (py, n=2 (2; 2-picoline(2-pic, n=0 (3; 3-picoline(3-pic, n=2 (4; and 4-picoline(4-pic, n=0 (5 and homobimetallic nickel(II complexes [Ni2(nsh(A4]·nH2O (where A = water (H2O, n=1 (6; pyridine (py, n=4 (7; 2-picoline(2-pic, n=4 (8; 3-picoline(3-pic, n=4 (9; and 4-picoline(4-pic, n=4 (10, resp. have been synthesized in methanol from bis(2-hydroxy-1-naphthaldehydesuccinoyldihydrazone (H4nsh. The complexes have been characterized by elemental analyses, molar conductance, magnetic moment, and electronic and IR and TGA/DTA spectroscopic studies. The monometallic complexes (1 to (5 are found to have octahedral stereochemistry while complexes (6 to (10 are found to have distorted octahedral stereochemistry in which one of the Ni(II centres is present in N2O2 coordination sphere and another Ni(II centre is bonded to it through phenolate oxygen atoms via oxo-bridging.

  14. Structural characterization of more potent alternatives to HAMLET, a tumoricidal complex of α-lactalbumin and oleic acid.

    Science.gov (United States)

    Nemashkalova, Ekaterina L; Kazakov, Alexei S; Khasanova, Leysan M; Permyakov, Eugene A; Permyakov, Sergei E

    2013-09-10

    HAMLET is a complex of human α-lactalbumin (hLA) with oleic acid (OA) that kills various tumor cells and strains of Streptococcus pneumoniae. More potent protein-OA complexes were previously reported for bovine α-lactalbumin (bLA) and β-lactoglobulin (bLG), and pike parvalbumin (pPA), and here we explore their structural features. The concentration dependencies of the tryptophan fluorescence of hLA, bLA, and bLG complexes with OA reveal their disintegration at protein concentrations below the micromolar level. Chemical cross-linking experiments provide evidence that association with OA shifts the distribution of oligomeric forms of hLA, bLA, bLG, and pPA toward higher-order oligomers. This effect is confirmed for bLA and bLG using the dynamic light scattering method, while pPA is shown to associate with OA vesicles. Like hLA binding, OA binding increases the affinity of bLG for small unilamellar dipalmitoylphosphatidylcholine vesicles, while pPA efficiently binds to the vesicles irrespective of OA binding. The association of OA with bLG and pPA increases their α-helix and cross-β-sheet content and resistance to enzymatic proteolysis, which is indicative of OA-induced protein structuring. The lack of excess heat sorption during melting of bLG and pPA in complex with OA and the presence of a cooperative thermal transition at the level of their secondary structure suggest that the OA-bound forms of bLG and pPA lack a fixed tertiary structure but exhibit a continuous thermal transition. Overall, despite marked differences, the HAMLET-like complexes that were studied exhibit a common feature: a tendency toward protein oligomerization. Because OA-induced oligomerization has been reported for other proteins, this phenomenon is inherent to many proteins.

  15. Synthesis, characterization, X-ray crystal structure, DFT calculation, DNA binding, and antimicrobial assays of two new mixed-ligand copper(II) complexes

    Science.gov (United States)

    Ebrahimipour, S. Yousef; Sheikhshoaie, Iran; Mohamadi, Maryam; Suarez, Sebastian; Baggio, Ricardo; Khaleghi, Moj; Torkzadeh-Mahani, Masoud; Mostafavi, Ali

    2015-05-01

    Two new Cu(II) complexes, [Cu(L)(phen)] (1), [Cu(L)(bipy)] (2), where L2- = (3-methoxy-2oxidobenzylidene)benzohydrazidato, phen = 1,10 phenanthroline, and bipy = 2,2‧ bipyridine, were prepared and fully characterized using elemental analyses, FT-IR, molar conductivity, and electronic spectra. The structures of both complexes were also determined by X-ray diffraction. It was found that, both complexes possessed square pyramidal coordination environment in which, Cu(II) ions were coordinated by donor atoms of HL and two nitrogens of heterocyclic bases. Computational studies were performed using DFT calculations at B3LYP/6-311+G(d,p) level of theory. DNA binding activities of these complexes were also investigated using electronic absorption, competitive fluorescence titration and cyclic voltammetry studies. The obtained results indicated that binding of the complexes to DNA was of intercalative mode. Furthermore, antimicrobial activities of these compounds were screened against microorganisms.

  16. Synthesis, structural characterization and evaluation of catalytic and antimicrobial properties of new mononuclear Ag(I), Mn(II), Cu(II) and Pt(IV) complexes

    Science.gov (United States)

    Ali, Omyma A. M.; Abd El-Wahab, Zeinab H.; Ismail, Basmh A.

    2017-07-01

    New mononuclear complexes of composition [AgL(H2O)2]NO3·H2O, [MnL2Cl(H2O)]Cl.3½H2O, [CuL2Cl2].½H2O and [PtLCl3(H2O)]Cl·2H2O {where L was 1-(2-furylmethylene)-N-(3-phenylallylidene) methanamine} were synthesized and characterized by different techniques. From the analytical data, the stoichiometry of the complexes were 1:1 for Ag(I) and Pt(IV) complexes and 1:2 (M:L) for Mn(II) and Cu(II) complexes. Conductance data indicated that all complexes are electrolytic in nature while, Cu(II) complex was non-electrolyte. Spectroscopic data suggested that the ligand behaves as a neutral bidentate ligand towards the central metal ion with azomethine nitrogen and furan oxygen atoms as coordination sites. Tetrahedral structure has been proposed for Ag(I) complex, whereas the other complexes possess six coordinated octahedral geometry. TG-DTG study was done to track the thermal behavior of the complexes and the thermodynamic parameters were computed from the thermal data using Coats - Redfern method. The catalytic activity of the metal complexes was evaluated in the decomposition reaction of hydrogen peroxide at 313-333 K temperature range. The data reveal that metal complexes are effective in catalyzing the hydrogen peroxide decomposition and the decomposition percentage increased with temperature. The agar well diffusion technique was used to test the growth inhibition of the ligand and its complexes against different species of bacteria and fungi. The metal complexes are more potent in inhibiting the growth of microorganisms than the ligand and in some cases, the complexes were closed to and more active than the standard species.

  17. Electrochemical synthesis and structural characterization of a novel mixed-valence copper(I)-copper(II) complex: {[bis(ethylenediamine)copper(II)] bis[diiodocuprate(I)]}.

    Science.gov (United States)

    Fotouhi, Lida; Dehghanpour, Saeed; Heravi, Majid M; Ardakani, Mahboobeh Dashti

    2007-07-12

    A novel, mixed-valent copper(I)-copper(II) complex, {[bis(ethylene-diamine)copper(II)] bis[diiodocuprate(I)]} (1), has been prepared by electrochemical dissolution of a sacrificial copper anode in a solution of ethylenediamine (en), I2 and tetraethylammoniumperchlorate (TEAP) as supporting electrolyte in acetonitrile (AcN)and characterized by single-crystal X-ray structure determination. The crystal structure of the complex 1 shows that it consists of a CuI2 polymer formed from I- ligands bridging Cu(I) ions, with a nearly square planar geometry of bivalent Cu(II) atoms chelated by two ethylenediamine ligands. The results also show that direct electrosynthesis of the complex had high current efficiency, purity and electrolysis yield.

  18. Syntheses, crystal structures, and characterization of three 1D, 2D and 3D complexes based on mixed multidentate N- and O-donor ligands

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Huai-Xia, E-mail: yanghuaixia886@163.com [Pharmacy College, Henan University of Traditional Chinese Medicine, Zhengzhou 450008 (China); Liang, Zhen; Hao, Bao-Lian [Pharmacy College, Henan University of Traditional Chinese Medicine, Zhengzhou 450008 (China); Meng, Xiang-Ru, E-mail: mxr@zzu.edu.cn [The College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001 (China)

    2014-10-15

    Three new 1D to 3D complexes, namely, ([Ni(btec)(Himb){sub 2}(H{sub 2}O){sub 2}]·6H{sub 2}O){sub n} (1), ([Cd(btec){sub 0.5}(imb)(H{sub 2}O)]·1.5H{sub 2}O){sub n} (2), and ([Zn(btec){sub 0.5}(imb)]·H{sub 2}O){sub n} (3) (H{sub 4}btec=1,2,4,5-benzenetetracarboxylic acid, imb=2-(1H-imidazol-1-methyl)-1H-benzimidazole) have been synthesized by adjusting the central metal ions. Single-crystal X-ray diffraction analyses reveal that complex 1 possesses a 1D chain structure which is further extended into the 3D supramolecular architecture via hydrogen bonds. Complex 2 features a 2D network with Schla¨fli symbol (5{sup 3}·6{sup 2}·7)(5{sup 2}·6{sup 4}). Complex 3 presents a 3D framework with a point symbol of (4·6{sup 4}·8)(4{sup 2}·6{sup 2}·8{sup 2}). Moreover, their IR spectra, PXRD patterns, thermogravimetric curves, and luminescent emissions were studied at room temperature. - Graphical abstract: Three new 1D to 3D complexes with different structural and topological motifs have been obtained by modifying the central metal ions. Additionally, their IR, TG analyses and fluorescent properties are also investigated. - Highlights: • Three complexes based on mixed multidentate N- and O-donor ligands. • The complexes are characterized by IR, luminescence and TGA techniques. • Benzenetetracarboxylates display different coordination modes in complexes 1–3. • Changing the metal ions can result in complexes with completely different structures.

  19. Zinc complexes of diflunisal: Synthesis, characterization, structure, antioxidant activity, and in vitro and in silico study of the interaction with DNA and albumins.

    Science.gov (United States)

    Tarushi, Alketa; Kakoulidou, Chrisoula; Raptopoulou, Catherine P; Psycharis, Vassilis; Kessissoglou, Dimitris P; Zoi, Ioanna; Papadopoulos, Athanasios N; Psomas, George

    2017-05-01

    From the reaction of ZnCl2 with the non-steroidal anti-inflammatory drug diflunisal (Hdifl), complex [Zn(difl-O)2(MeOH)4], 1 was formed, while in the presence of a N,N'-donor heterocyclic ligand 2,2'-bipyridylamine (bipyam), 2,2'-bipyridine (bipy), 1,10-phenanthroline (phen) and 2,2'-dipyridylketone oxime (Hpko), the complexes [Zn(difl-O,O')2(bipyam)], 2, [Zn(difl-O,O')2(bipy)], 3, [Zn(difl-O,O')2(phen)], 4 and [Zn(difl-O)2(Hpko)2], 5 were isolated, respectively. The complexes were characterized by physicochemical and spectroscopic techniques and the crystal structures of complexes 2, 3 and 5 were determined by X-ray crystallography. The ability of the complexes to scavenge 1,1-diphenyl-picrylhydrazyl, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) and hydroxyl radicals and to inhibit soybean lipoxygenase was studied and the complexes were more active than free Hdifl. The interaction of the complexes with serum albumins was monitored by fluorescence emission spectroscopy and the corresponding binding constants were calculated. UV-vis spectroscopy, viscosity measurements and fluorescence emission spectroscopy for the competitive studies of the complexes with ethidium bromide were employed to investigate the interaction of the complexes with calf-thymus DNA and revealed intercalation as the most possible DNA-binding mode. Computational techniques were used to identify possible binding sites of albumins and DNA, and determine the druggability of human and bovine serum albumins with the five novel complexes. The majority of the complexes are stronger binders than the free Hdifl. This is the first study incorporating experimental and computational results to explore the binding activity of metal-NSAID complexes with DNA and serum albumins, suggesting their application as potential metallodrugs. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Phenoxo bridged dinuclear Zn(II) Schiff base complex as new precursor for preparation zinc oxide nanoparticles: Synthesis, characterization, crystal structures and photoluminescence studies

    Energy Technology Data Exchange (ETDEWEB)

    Saeednia, S., E-mail: sami_saeednia@yahoo.com [Department of Chemistry, Faculty of Science, Vali-e-Asr University of Rafsanjan, Rafsanjan 77188-97111 (Iran, Islamic Republic of); Iranmanesh, P. [Department of physics, Faculty of Science, Vali-e-Asr University of Rafsanjan, Rafsanjan 77188-97111 (Iran, Islamic Republic of); Ardakani, M. Hatefi; Mohammadi, M.; Norouzi, Gh. [Department of Chemistry, Faculty of Science, Vali-e-Asr University of Rafsanjan, Rafsanjan 77188-97111 (Iran, Islamic Republic of)

    2016-06-15

    Highlights: • A novel nano-scale Zn(II) complex was synthesized by solvothermal method. • Chemical structure of the nanostructures was characterized as well as bulk complex. • The photoluminescence property of the complex was investigated at room temperature. • The thermogravimetry and differential thermal analysis were carried out. • Thermal decomposition of the nanostructures was prepared zinc oxide nanoparticles. - Abstract: Nanoparticles of a novel Zn(II) Schiff base complex, [Zn(HL)NO{sub 3}]{sub 2} (1), (H{sub 2}L = 2-[(2-hydroxy-propylimino) methyl] phenol), was synthesized by using solvothermal method. Shape, morphology and chemical structure of the synthesized nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier Transform Infrared Spectoscopy (FT-IR) and UV–vis spectroscopy. Structural determination of compound 1 was determined by single-crystal X-ray diffraction. The results were revealed that the zinc complex is a centrosymmetric dimer in which deprotonated phenolates bridge the two five-coordinate metal atoms and link the two halves of the dimer. The thermal stability of compound 1 was analyzed by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The effect of the initial substrates concentration and reaction time on size and morphology of compound 1 nanostructure was investigated as well. Furthermore, the luminescent properties of the complex 1 were examined. ZnO nanoparticles with diameter between 15 and 20 nm were simply synthesized by solid-state transformation of compound 1 at 700 °C.

  1. Synthesis and structural characterization of new oxorhenium and oxotechnetium complexes with XN2S-tetradentate semi-rigid ligands (X = O, S, N).

    Science.gov (United States)

    Le Gal, Julien; Tisato, Francesco; Bandoli, Giuliano; Gressier, Marie; Jaud, Joël; Michaud, Sandra; Dartiguenave, Michèle; Benoist, Eric

    2005-12-07

    Twelve novel oxo-technetium and oxo-rhenium complexes based on N2S2-, N2SO- or N3S-tetradentate semi-rigid ligands have been synthesised and studied herein. By reacting the ligands with a slight excess of suitable [MO]3+ precursor (ReOCl3(PPh3)2 or [NBu4][99gTcOCl4]), the monoanionic complexes of general formula [MO(Ph-XN2S)]- could be easily produced in high yield. The complexes have been characterized by means of IR, electrospray mass spectrometry, elemental analysis, NMR and conductimetry. The crystal structures of [PPh4][ReO(Ph-ON2S)] 1b and [NBu4][99gTcO(Ph-ON2S)] 1c have been established. The [MO]3+ moiety was coordinated via the two deprotonated amide nitrogens, the oxygen and the terminal sulfur atoms in 1b and 1c. In both compounds, the ON2S coordination set is in the equatorial plane, and the complexes adopted a distorted square-pyramidal geometry with an axial oxo-group. The chemical and structural identity of the different prototypic complexes (rhenium, 99gTc complexes and their corresponding 99mTc radiocomplexes) have been also established by a comparative HPLC study.

  2. Synthesis, crystal structure, spectroscopic characterization and nonlinear optical properties of manganese (II) complex of picolinate: A combined experimental and computational study

    Science.gov (United States)

    Tamer, Ömer; Avcı, Davut; Atalay, Yusuf; Çoşut, Bünyemin; Zorlu, Yunus; Erkovan, Mustafa; Yerli, Yusuf

    2016-02-01

    A novel manganese (II) complex with picolinic acid (pyridine 2-carboxylic acid, Hpic), namely, [Mn(pic)2(H2O)2] was prepared and its crystal structure was fully characterized by using single crystal X-ray diffraction. Picolinate (pic) ligands were coordinated to the central manganese(II) ion as bidentate N,O-donors through the nitrogen atoms of pyridine rings and the oxygen atoms of carboxylate groups forming five-membered chelate rings. The spectroscopic characterization of Mn(II) complex was performed by the applications of FT-IR, Raman, UV-vis and EPR techniques. In order to support these studies, density functional theory (DFT) calculations were carried out by using B3LYP level. IR and Raman spectra were simulated at B3LYP level, and obtained results indicated that DFT calculations generally give compatible results to the experimental ones. The electronic structure of the Mn(II) complex was predicted using time dependent DFT (TD-DFT) method with polarizable continuum model (PCM). Molecular stability, hyperconjugative interactions, intramolecular charge transfer (ICT) and bond strength were investigated by applying natural bond orbital (NBO) analysis. Nonlinear optical properties of Mn(II) complex were investigated by the determining of molecular polarizability (α) and hyperpolarizability (β) parameters.

  3. Structural and Functional Characterization of an Archaeal Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)-associated Complex for Antiviral Defense (CASCADE)

    DEFF Research Database (Denmark)

    Lintner, Nathanael G; Kerou, Melina; Brumfield, Susan K

    2011-01-01

    In response to viral infection, many prokaryotes incorporate fragments of virus-derived DNA into loci called clustered regularly interspaced short palindromic repeats (CRISPRs). The loci are then transcribed, and the processed CRISPR transcripts are used to target invading viral DNA and RNA....... The Escherichia coli "CRISPR-associated complex for antiviral defense" (CASCADE) is central in targeting invading DNA. Here we report the structural and functional characterization of an archaeal CASCADE (aCASCADE) from Sulfolobus solfataricus. Tagged Csa2 (Cas7) expressed in S. solfataricus co-purifies with Cas5......a-, Cas6-, Csa5-, and Cas6-processed CRISPR-RNA (crRNA). Csa2, the dominant protein in aCASCADE, forms a stable complex with Cas5a. Transmission electron microscopy reveals a helical complex of variable length, perhaps due to substoichiometric amounts of other CASCADE components. A recombinant Csa2...

  4. Synthesis, characterization and luminescence of europium perchlorate with MABA-Si complex and coating structure SiO2@Eu(MABA-Si) luminescence nanoparticles.

    Science.gov (United States)

    Fu, Zhi-Fang; Li, Wen-Xian; Bai, Juan; Bao, Jin-Rong; Cao, Xiao-Fang; Zheng, Yu-Shan

    2017-05-01

    This article reports a novel category of coating structure SiO 2 @Eu(MABA-Si) luminescence nanoparticles (NPs) consisting of a unique organic shell, composed of perchlorate europium(III) complex, and an inorganic core, composed of silica. The binary complex Eu(MABA-Si) 3 ·(ClO 4 ) 3 ·5H 2 O was synthesized using HOOCC 6 H 4 N(CONH(CH 2 ) 3 Si(OCH 2 CH 3 ) 3 ) 2 (MABA-Si) and was used as a ligand. Furthermore, the as-prepared silica NPs were successfully coated with the -Si(OCH 2 CH 3 ) 3 group of MABA-Si to form Si-O-Si chemical bonds by means of the hydrolyzation of MABA-Si. The binary complexes were characterized by elemental analysis, molar conductivity and coordination titration analysis. The results indicated that the composition of the binary complex was Eu(MABA-Si) 3 ·(ClO 4 ) 3 ·5H 2 O. Coating structure SiO 2 @Eu(MABA-Si) NPs were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and infrared (IR) spectra. Based on the SEM and TEM measurements, the diameter of core-SiO 2 particles was ~400 and 600 nm, and the thickness of the cladding layer Eu(MABA-Si) was ~20 nm. In the binary complex Eu(MABA-Si) 3 ·(ClO 4 ) 3 ·5H 2 O, the fluorescence spectra illustrated that the energy of the ligand MABA-Si transferred to the energy level for the excitation state of europium(III) ion. Coating structure SiO 2 @Eu(MABA-Si) NPs exhibited intense red luminescence compared with the binary complex. The fluorescence lifetime and fluorescence quantum efficiency of the binary complex and of the coating structure NPs were also calculated. The way in which the size of core-SiO 2 spheres influences the luminescence was also studied. Moreover, the luminescent mechanisms of the complex were studied and explained. Copyright © 2016 John Wiley & Sons, Ltd.

  5. Structural and functional characterization of an archaeal clustered regularly interspaced short palindromic repeat (CRISPR)-associated complex for antiviral defense (CASCADE).

    Science.gov (United States)

    Lintner, Nathanael G; Kerou, Melina; Brumfield, Susan K; Graham, Shirley; Liu, Huanting; Naismith, James H; Sdano, Matthew; Peng, Nan; She, Qunxin; Copié, Valérie; Young, Mark J; White, Malcolm F; Lawrence, C Martin

    2011-06-17

    In response to viral infection, many prokaryotes incorporate fragments of virus-derived DNA into loci called clustered regularly interspaced short palindromic repeats (CRISPRs). The loci are then transcribed, and the processed CRISPR transcripts are used to target invading viral DNA and RNA. The Escherichia coli "CRISPR-associated complex for antiviral defense" (CASCADE) is central in targeting invading DNA. Here we report the structural and functional characterization of an archaeal CASCADE (aCASCADE) from Sulfolobus solfataricus. Tagged Csa2 (Cas7) expressed in S. solfataricus co-purifies with Cas5a-, Cas6-, Csa5-, and Cas6-processed CRISPR-RNA (crRNA). Csa2, the dominant protein in aCASCADE, forms a stable complex with Cas5a. Transmission electron microscopy reveals a helical complex of variable length, perhaps due to substoichiometric amounts of other CASCADE components. A recombinant Csa2-Cas5a complex is sufficient to bind crRNA and complementary ssDNA. The structure of Csa2 reveals a crescent-shaped structure unexpectedly composed of a modified RNA-recognition motif and two additional domains present as insertions in the RNA-recognition motif. Conserved residues indicate potential crRNA- and target DNA-binding sites, and the H160A variant shows significantly reduced affinity for crRNA. We propose a general subunit architecture for CASCADE in other bacteria and Archaea.

  6. Lanthanide complexes of macrocyclic polyoxovanadates by VO4 units: synthesis, characterization, and structure elucidation by X-ray crystallography and EXAFS spectroscopy.

    Science.gov (United States)

    Nishio, Masaki; Inami, Shinnosuke; Katayama, Misaki; Ozutsumi, Kazuhiko; Hayashi, Yoshihito

    2012-01-16

    Reactions of a tetravanadate anion, [V(4)O(12)](4-), with a series of lanthanide(III) salts yield three types of lanthanide complexes of macrocyclic polyoxovanadates: (Et(4)N)(6)[Ln(III)V(9)O(27)] [Ln = Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6)], (Et(4)N)(5)[(H(2)O)Ho(III)(V(4)O(12))(2)] (7), and (Et(4)N)(7)[Ln(III)V(10)O(30)] [Ln = Er (8), Tm (9), Yb (10), Lu (11)]. Lanthanide complexes 1-11 are isolated and characterized by IR, elemental analysis, single-crystal X-ray diffraction, and extended X-ray absorption fine structure spectroscopy (EXAFS). Lanthanide complexes 1-6 are composed of a square-antiprism eight-coordinated Ln(III) center with a macrocyclic polyoxovanadate that is constructed from nine VO(4) tetrahedra through vertex sharing. The structure of 7 is composed of a seven-coordinated Ho(III) center, which exhibits a capped trigonal-prism coordination environment by the sandwiching of two cyclic tetravanadates with a capping H(2)O ligand. Lanthanide complexes 8-11 have a six-coordinated Ln(III) center with a 10-membered vanadate ligand. The structural trend to adopt a larger coordination number for a larger lanthanide ion among the three types of structures is accompanied by a change in the vanadate ring sizes. These lanthanide complexes are examined by EXAFS spectroscopies on lanthanide L(III) absorption edges, and the EXAFS oscillations of each of the samples in the solid state and in acetonitrile are identical. The Ln-O and Ln···V bond lengths obtained from fits of the EXAFS data are consistent with the data from the single-crystal X-ray studies, reflecting retention of the structures in acetonitrile.

  7. Structural and spectroscopic characterization of iron(II), cobalt(II), and nickel(II) ortho-dihalophenolate complexes: insights into metal-halogen secondary bonding.

    Science.gov (United States)

    Machonkin, Timothy E; Boshart, Monica D; Schofield, Jeremy A; Rodriguez, Meghan M; Grubel, Katarzyna; Rokhsana, Dalia; Brennessel, William W; Holland, Patrick L

    2014-09-15

    Metal complexes incorporating the tris(3,5-diphenylpyrazolyl)borate ligand (Tp(Ph2)) and ortho-dihalophenolates were synthesized and characterized in order to explore metal-halogen secondary bonding in biorelevant model complexes. The complexes Tp(Ph2)ML were synthesized and structurally characterized, where M was Fe(II), Co(II), or Ni(II) and L was either 2,6-dichloro- or 2,6-dibromophenolate. All six complexes exhibited metal-halogen secondary bonds in the solid state, with distances ranging from 2.56 Å for the Tp(Ph2)Ni(2,6-dichlorophenolate) complex to 2.88 Å for the Tp(Ph2)Fe(2,6-dibromophenolate) complex. Variable temperature NMR spectra of the Tp(Ph2)Co(2,6-dichlorophenolate) and Tp(Ph2)Ni(2,6-dichlorophenolate) complexes showed that rotation of the phenolate, which requires loss of the secondary bond, has an activation barrier of ~30 and ~37 kJ/mol, respectively. Density functional theory calculations support the presence of a barrier for disruption of the metal-halogen interaction during rotation of the phenolate. On the other hand, calculations using the spectroscopically calibrated angular overlap method suggest essentially no contribution of the halogen to the ligand-field splitting. Overall, these results provide the first quantitative measure of the strength of a metal-halogen secondary bond and demonstrate that it is a weak noncovalent interaction comparable in strength to a hydrogen bond. These results provide insight into the origin of the specificity of the enzyme 2,6-dichlorohydroquinone 1,2-dioxygenase (PcpA), which is specific for ortho-dihalohydroquinone substrates and phenol inhibitors.

  8. Metal-promoted synthesis, characterization, crystal structure and RNA cleavage ability of 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone) lanthanide complexes.

    Science.gov (United States)

    Kozłowski, Michał; Kierzek, Ryszard; Kubicki, Maciej; Radecka-Paryzek, Wanda

    2013-09-01

    New 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone) lanthanide complexes were formed in the metal-induced one-step [1+2] condensation reaction between 2,6-diacetylpyridine and 2-aminobenzoylhydrazide in the presence of lanthanide (La(3+), Pr(3+), Nd(3+), Sm(3+), Eu(3+), Gd(3+), Tb(3+), Dy(3+), Ho(3+), Er(3+), Tm(3+) or Yb(3+)) nitrates as template agents. The analytical and spectral characterizations of all the compounds were correlated with the single crystal X-ray structural determination of Eu(3+), Gd(3+), Tb(3+), Dy(3+) and Er(3+) nitrate complexes. The Eu(3+), Gd(3+), Tb(3+)and Dy(3+) complexes of pentadentate 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone) with the N3O2 set of donor atoms display a high and relatively rare coordination number of 11, whereas the Er(3+) ion complex is 9-coordinated, which is consistent with the lanthanide contraction phenomenon. The scission of 21-mer RNA was assessed for Eu(3+), Gd(3+) and Tb(3+) nitrate complexes. Lanthanide complexes not covalently attached to the oligonucleotide are able to cleave RNA at the target site in a sequence-selective or non-selective manner depending on the presence of protecting 12-mer 2'OMe RNA. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. Synthesis, crystal structure and spectral characterization of the first Ag+ complex compounds involving O,N,O-coordinated N-acylhydrazones of salicylaldehyde

    Science.gov (United States)

    Repich, H. H.; Orysyk, S. I.; Orysyk, V. V.; Zborovskii, Yu. L.; Pekhnyo, V. I.; Vovk, M. V.

    2017-09-01

    N-acylhydrazones of salicylaldehyde is a well known class of ligands bearing O,N,O tridentate chelate coordination site. But up to now no structurally characterized Ag+ complexes with O,N,O coordinated N-acylhydrazones of salicylaldehyde were known. Therefore three Ag+ coordination compounds with functionally substituted N-acylhydrazones of salicylaldehyde were synthesized and characterized by X-ray diffraction, IR spectroscopy and thermogravimetric studies. In solutions the complexes were studied by 1H NMR and UV-Vis spectroscopy. The influence of the presence and location of additional nitrogen donor atoms in N-acylhydrazones of salicylaldehyde on their coordination modes was investigated. Ligand N'-salicylidenephenylacetohydrazide (contains no additional donor atoms) coordinates to Ag+ in classical O,N,O tridentate chelate manner. Ligand N‧-salicylidene-3-pyridinecarbohydrazide (contains β-N additional donor atom in acyl moiety) involves mixed O,N,O + β-N coordination. Whereas N'-salicylidene-4-pyridinecarbohydrazide (contains γ-N additional donor atom) coordinates to Ag+ in monodentate manner only via γ-N atom of heterocyclic substituent. All the complexes provide high coordination numbers of Ag+ and irregular shapes of coordination polyhedra which are not consistent with classical concepts of Ag+ coordination chemistry. However all the complexes are not thermally stable and easily undergo solvolysis upon dissolution.

  10. Structural characterization of a noncovalent complex between ubiquitin and the transactivation domain of the erythroid-specific factor EKLF.

    Science.gov (United States)

    Raiola, Luca; Lussier-Price, Mathieu; Gagnon, David; Lafrance-Vanasse, Julien; Mascle, Xavier; Arseneault, Genevieve; Legault, Pascale; Archambault, Jacques; Omichinski, James G

    2013-11-05

    Like other acidic transactivation domains (TAD), the minimal TAD from the erythroid-specific transcription factor EKLF (EKLFTAD) has been shown to contribute both to its transcriptional activity as well as to its ubiquitin(UBI)-mediated degradation. In this article, we examine the activation-degradation role of the acidic TAD of EKLF and demonstrate that the first 40 residues (EKLFTAD1) within this region form a noncovalent interaction with UBI. Nuclear magnetic resonance (NMR) structural studies of an EKLFTAD1-UBI complex show that EKLFTAD1 adopts a 14-residue α helix that forms the recognition interface with UBI in a similar manner as the UBI-interacting helix of Rabex5. We also identify a similar interaction between UBI and the activation-degradation region of SREBP1a, but not with the activation-degradation regions of p53, GAL4, and VP16. These results suggest that select activation-degradation regions like the ones found in EKLF and SREBP1a function in part through their ability to form noncovalent interactions with UBI. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Ternary complexes of copper(II) and cobalt(II) involving nitrite/pyrazole and tetradentate N4-coordinate ligand: Synthesis, characterization, structures and antimicrobial activity

    Science.gov (United States)

    Solanki, Ankita; Sadhu, Mehul H.; Kumar, Sujit Baran

    2015-12-01

    Five new mononuclear mixed ligand complexes of the type [Cu(NCCH3)(dbdmp)](ClO4)2, [M(ONO)(dbdmp)]ClO4, [M(pz) (dbdmp)](ClO4)2 where M = Cu(II) and Co(II), pz = 3,5-dimethylpyrazole and dbdmp = N,N-diethyl-N‧,N‧-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)ethane-1,2-diamine have been synthesized and characterized by physico-chemical and spectroscopy studies. The crystal structures of three copper(II) complexes [Cu(NCCH3)(dbdmp)](ClO4)2, [Cu(ONO)(dbdmp)]ClO4 and [Cu(pz)(dbdmp)](ClO4)2 have been determined by single crystal X-ray diffraction studies. Structural analyses reveal the geometry of [Cu(pz)(dbdmp)](ClO4)2 is distorted square pyramidal and other two copper(II) complexes have distorted trigonal bipyramidal geometry. Molecular composition of cobalt(II) complexes have been determined by mass spectral data. The EPR spectra of copper(II) complexes in frozen acetonitrile solution exhibit axial spectra, characteristic of dx2-y2 ground state. Electrochemical studies of copper(II) complexes using glassy carbon as working electrode in acetonitrile solution show Cu(II)/Cu(I) couple with quasi reversible electron transfer versus Ag/Ag+ reference electrode. Antimicrobial activity of all the synthesized complexes were investigated against two Gram positive and two Gram negative bacterial strains.

  12. Synthesis, characterization, crystal structure and antibacterial activities of transition metal(II) complexes of the schiff base 2-[(4-methylphenylimino)methyl]-6-methoxyphenol.

    Science.gov (United States)

    Yu, Yu-Ye; Xian, Hui-Duo; Liu, Jian-Feng; Zhao, Guo-Liang

    2009-05-07

    Five transition metal(II) complexes, [ML(2)Cl(2)] 1 approximately 5, were synthesized from the reaction of MCl(2) x nH(2)O (M = Mn, Co, Ni, Cu, Cd) and the Schiff base ligand 2-[(4-methylphenylimino)methyl]-6-methoxyphenol (C(15)H(15)NO(2), L), obtained by condensation of o-vanillin (2-hydroxy-3-methoxybenzaldehyde) with p-toluidine. They were characterized by elemental analysis, molar conductance, FT-IR spectra, thermal analysis. The structure of complex 1 was determined by single-crystal X-ray diffraction. Its crystal structure is of monoclinic system, space group P2(1)/c with a = 9.0111(18) A, b = 11.222(2) A, c =28.130 (6) A, alpha = 90 masculine, beta = 92.29(3) masculine, gamma = 90 masculine, V = 2867.6(10) A(3), Z = 4. The Mn atom is six-coordinate and displays distorted octahedral geometry.The Schiff base ligand and its complexes have been tested in vitro to evaluate their antibacterial activity against bacteria, viz., Escherichia coli, Staphylococcus aureus and Bacillus subtilis. It has been found that the complexes have higher activity than the corresponding free Schiff base ligand against the same bacteria.

  13. Synthesis, Characterization, Crystal Structure and Antibacterial Activities of Transition Metal(II Complexes of the Schiff Base 2-[(4-Methylphenyliminomethyl]-6-methoxyphenol

    Directory of Open Access Journals (Sweden)

    Guo-Liang Zhao

    2009-05-01

    Full Text Available Five transition metal(II complexes, [ML2Cl2] 1~5, were synthesized from the reaction of MCl2·nH2O (M = Mn, Co, Ni, Cu, Cd and the Schiff base ligand 2-[(4-methylphenyliminomethyl]-6-methoxyphenol (C15H15NO2, L, obtained by condensation of o-vanillin (2-hydroxy-3-methoxybenzaldehyde with p-toluidine. They were characterized by elemental analysis, molar conductance, FT-IR spectra, thermal analysis. The structure of complex 1 was determined by single-crystal X-ray diffraction. Its crystal structure is of monoclinic system, space group P21/c with a = 9.0111(18 Å, b = 11.222(2 Å, c =28.130 (6 Å, α = 90 º, β = 92.29(3 º, γ = 90 º, V = 2867.6(10 Å3, Z = 4. The Mn atom is six-coordinate and displays distorted octahedral geometry.The Schiff base ligand and its complexes have been tested in vitro to evaluate their antibacterial activity against bacteria, viz., Escherichia coli, Staphylococcus aureus and Bacillus subtilis. It has been found that the complexes have higher activity than the corresponding free Schiff base ligand against the same bacteria.

  14. Synthesis and characterization of a new zinc(II) complex with tetradentate azo-thioether ligand: X-ray structure, DNA binding study and DFT calculation

    Science.gov (United States)

    Mondal, Apurba Sau; Pramanik, Ajoy Kumar; Patra, Lakshman; Manna, Chandan Kumar; Mondal, Tapan Kumar

    2017-10-01

    A new zinc(II) complex, [Zn(L)(H2O)](ClO4) (1) with azo-thioether containing NSNO donor ligand, 3-(2-(2-((pyridin-2-ylmethyl)thio)phenyl)hydrazono)pentane-2,4-dione (HL) is synthesized and characterized by several spectroscopic techniques. The distorted square based pyramidal (DSBP) geometry is confirmed by single crystal X-ray structure. The ability of the complex to bind with CT DNA is investigated by UV-vis method and the binding constant is found to be 4.16 × 104 M-1. Competitive binding study with ethidium bromide (EB) by fluorescence method suggests that the zinc(II) complex efficiently displaces EB from EB-DNA. The Stern-Volmer dynamic quenching constant, Ksv is found to be 1.2 × 104 M-1. Theoretical calculations by DFT and TDDFT/CPCM methods are used to interpret the electronic structure and UV-vis spectrum of the complex.

  15. Characterization of the sialidase molecular defects in sialidosis patients suggests the structural organization of the lysosomal multienzyme complex.

    Science.gov (United States)

    Lukong, K E; Elsliger, M A; Chang, Y; Richard, C; Thomas, G; Carey, W; Tylki-Szymanska, A; Czartoryska, B; Buchholz, T; Criado, G R; Palmeri, S; Pshezhetsky, A V

    2000-04-12

    Sialidosis is an autosomal recessive disease caused by the genetic deficiency of lysosomal sialidase, which catalyzes the hydrolysis of sialoglycoconjugates. The disease is associated with progressive impaired vision, macular cherry-red spots and myoclonus (sialidosis type I) or with skeletal dysplasia, Hurler-like phenotype, dysostosis multiplex, mental retardation and hepatosplenomegaly (sialidosis type II). We have analyzed the genomic DNA from nine sialidosis patients of multiple ethnic origin in order to find mutations responsible for the enzyme deficiency. The activity of the identified variants was studied by transgenic expression. One patient had a frameshift mutation (G623delG deletion), which introduced a stop codon, truncating 113 amino acids. All others had missense mutations: G679G-->A (Gly227Arg), C893C-->T (Ala298Val), G203G-->T (Gly68Val), A544A-->G (Ser182Gly) C808C-->T (Leu270Phe) and G982G-->A (Gly328Ser). We have modeled the three-dimensional structure of sialidase based on the atomic coordinates of the homologous bacterial sialidases, located the positions of mutations and estimated their potential effect. This analysis showed that five mutations are clustered in one region on the surface of the sialidase molecule. These mutations dramatically reduce the enzyme activity and cause a rapid intralysosomal degradation of the expressed protein. We hypothesize that this region may be involved in the interface of sialidase binding with lysosomal cathepsin A and/or beta-galactosidase in their high-molecular-weight complex required for the expression of sialidase activity in the lysosome.

  16. Expression, Purification, and Screening of BamE, a Component of the BAM Complex, for Structural Characterization.

    Science.gov (United States)

    Jeeves, Mark; Sridhar, Pooja; Knowles, Timothy J

    2015-01-01

    In Gram-negative bacteria, integral outer membrane β-barrel proteins (OMP) are assembled by the β-barrel assembly machine complex, or BAM complex. This complex includes the essential components BamA, an OMP composed of a carboxyl terminal β-barrel domain and five polypeptide transport-associated domains (POTRA), and the lipoprotein BamD. In Escherichia coli, the complex contains an additional three lipoproteins, BamB, C and E required for efficient delivery of OMPs to the outer membrane. Here we provide methods for production, isotope labeling, purification, and functional screening of BamE for research purposes. Purification strategies of both the soluble and wild-type membrane-tethered forms of BamE are described using techniques including osmotic shock, Ni-NTA purification, and size-exclusion chromatography. Functional screening using a simple plate assay is also described which allows screening for defects in outer membrane permeability.

  17. Development of CdS Nanostructures by Thermal Decomposition of Aminocaproic Acid-Mixed Cd-Thiourea Complex Precursor: Structural, Optical and Photocatalytic Characterization.

    Science.gov (United States)

    Patel, Jayesh D; Mighri, Frej; Ajji, Abdellah; Chaudhuri, Tapas K

    2015-04-01

    The present work deals with two different CdS nanostructures produced via hydrothermal and solvothermal decompositions of aminocaproic acid (ACA)-mixed Cd-thiourea complex precursor at 175 °C. Both nanostructures were extensively characterized for their structural, morphological and optical properties. The powder X-ray diffraction characterization showed that the two CdS nanostructures present a wurtzite morphology. Scanning electron microscopy and energy-dispersive X-ray characterizations revealed that the hydrothermal decomposition produced well-shaped CdS flowers composed of six dendritic petals, and the solvothermal decomposition produced CdS microspheres with close stoichiometric chemical composition. The UV-vis absorption and photoluminescence spectra of CdS dendritic flowers and microsphere nanostructures showed that both nanostructures present a broad absorption between 200 and 700 nm and exhibit strong green emissions at 576 and 520 nm upon excitations at 290 nm and 260 nm, respectively. The transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) characterizations confirmed that CdS microspheres were mesoporous and were composed of small nanocrystals. A possible growth mechanism in the formation of the CdS nanostructures was proposed based on morphology evolution as a function of the reaction time. Furthermore, the as-synthesized CdS nanostructures were found to exhibit highly efficient photocatalytic activities for the degradation of methyl orange (MeO) and rhodamine B (RhB) dyes.

  18. Mössbauer spectroscopic studies and structural characterization of oxo-centered trinuclear iron carboxylato-aquo complexes

    Science.gov (United States)

    Sato, T.; Nakamoto, T.; Katada, M.; Endo, K.; Sano, H.

    1994-12-01

    Mixed-valence states of [Fe3O(CH2ClCO2)6(H2O)3] nH2O ( n=0 and 3) were studied by means of Mössbauer spectroscopy and single-crystal X-ray crystallography. The number of water molecules of crystallization was determined by X-ray crystallography. The dehydrated complex was obtained by storing the trihydrated complex under a dry atmosphere. It was found that the temperature dependence of the mixed-valence state is affected by the hydrated water molecules.

  19. Single particle cryoelectron tomography characterization of the structure and structural variability of poliovirus-receptor-membrane complex at 30-Angstroms resolution

    Science.gov (United States)

    Bostina, Mihnea; Bubeck, Doryen; Schwartz, Cindi; Nicastro, Daniela; Filman, David J.; Hogle, James M.

    2007-01-01

    As a long-term goal we want to use cryoelectron tomography to understand how non-enveloped viruses, such as picornaviruses, enter cells and translocate their genomes across membranes. To this end, we developed new image-processing tools using an in vitro system to model viral interactions with membranes. The complex of poliovirus with its membrane-bound receptors was reconstructed by averaging multiple sub-tomograms, thereby producing three-dimensional maps of surprisingly high resolution (30Å). Recognizable images of the complex could be produced by averaging as few as 20 copies. Additionally, model-free reconstructions of free poliovirus particles, clearly showing the major surface features, could be calculated from 60 virions. All calculations were designed to avoid artifacts caused by missing information typical for tomographic data (“missing wedge”). To investigate structural and conformational variability we applied a principal component analysis classification to specific regions. We show that the missing wedge causes a bias in classification, and that this bias can be minimized by supplementation with data from the Fourier transform of the averaged structure. After classifying images of the receptor into groups with high similarity, we were able to see differences in receptor density consistent with the known variability in receptor glycosylation. PMID:17897840

  20. Synthesis, Characterization, Crystal Structure and Antimicrobial Activity of Copper(II Complexes with the Schiff Base Derived from 2-Hydroxy-4-Methoxybenzaldehyde

    Directory of Open Access Journals (Sweden)

    Elena Pahonțu

    2015-04-01

    Full Text Available A novel Schiff base, ethyl 4-[(E-(2-hydroxy-4-methoxyphenylmethylene-amino]benzoate (HL, was prepared and structurally characterized on the basis of elemental analyses, 1H NMR, 13C NMR, UV-Vis and IR spectral data. Six new copper(II complexes, [Cu(L(NO3(H2O2] (1, [Cu(L2] (2, [Cu(L(OAc] (3, [Cu2 (L2Cl2(H2O4] (4, [Cu(L(ClO4(H2O] (5 and [Cu2(L2S(ClO4(H2O]ClO4·H2O (6 have been synthesized. The characterization of the newly formed compounds was done by IR, UV-Vis, EPR, FAB mass spectroscopy, elemental and thermal analysis, magnetic susceptibility measurements and molar electric conductivity. The crystal structures of Schiff base and the complex [Cu2(L2S(ClO4(H2O]ClO4·H2O (6 have been determined by single crystal X-ray diffraction studies. Both copper atoms display a distorted octahedral coordination type [O4NS]. This coordination is ensured by three phenol oxygen, two of which being related to the µ-oxo-bridge, the nitrogen atoms of the azomethine group and the sulfur atoms that come from the polydentate ligand. The in vitro antimicrobial activity against Escherichia coli ATCC 25922, Salmonella enteritidis, Staphylococcus aureus ATCC 25923, Enterococcus and Candida albicans strains was studied and compared with that of free ligand. The complexes 1, 2, 5 showed a better antimicrobial activity than the Schiff base against the tested microorganisms.

  1. Synthesis, characterization, electrochemical studies and X-ray structures of mixed-ligand polypyridyl copper(II complexes with the acetate

    Directory of Open Access Journals (Sweden)

    Adekunle Oluwafunmilayo F.

    2016-01-01

    Full Text Available [Cu(phen2(CH3COO](ClO4.2H2O (1 and [Cu(bipy2(CH3COO]-(ClO4.H2O (2 {phen = 1,10-phenanthroline, bipy = 2,2’-bipyridine}were synthesized and characterized. The complexes were characterized by employying elemental analyses, infrared and UV-Visible spectroscopy, room temperature magnetic measurements and the crystal structures elucidated using X-ray diffraction experiment. The redox properties of the complexes were also investigated. Both structures have a square pyramidal CuN4O chromophore which exhibit significant distortions due to long Cu-O [2.217(3 Å for (1 and 2.179 (1 for (2] and Cu-N [2.631(2 Å for (1 and 2.714(1 Å for (2] bonds. This distortion if further shown by the O-Cu-N bond angles [147.71(8 o for (1 and 153.40(5 o for (2]. The elemental analyses further support the structural details unveiled by the single crystal X-ray diffraction analysis. The infrared spectra shows the acetate vibrational frequencies at 1587 cm-1,1428 cm-1, 1314 cm-1 for (1 and 1571 cm-1, 1441 cm-1, 1319c m-1 for (2 and the perchlo-rate bands at 1059 cm-1, 720 cm-1 (1 and 1080 cm-1,768 cm-1 (2. The broad d-d bands for the copper ion at 14,514 cm-1(1 and 14,535 cm-1(2 support the adoption of square pyramid geometries. The magnetic moments for the two complexes are 1.83 B.M for (1 and 1.72 B.M for (2. The peak to peak values of the two complexes show that the electrode reactions are quasi-reversibile with ΔEp = 0.023V (1 and 0.025V for (2. In both structures, there are π-π intermolecular interactions in addition to hydrogen bonding between the units.

  2. Synthesis, spectroscopic and structural characterization of new ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 125; Issue 3. Synthesis, spectroscopic and structural characterization of new linear mononuclear silver(I) complexes containing -keto phosphorus ylides as ambidentate ligands. Seyed Javad Sabounchei Mohsen Ahmadi Fatemeh Akhlaghi Hamid Reza Khavasi.

  3. Synthesis, structure characterization, DNA binding, and cleavage properties of mononuclear and tetranuclear cluster of copper(II) complexes.

    Science.gov (United States)

    Vafazadeh, Rasoul; Hasanzade, Naime; Heidari, Mohammad Mehdi; Willis, Anthony C

    2015-01-01

    Two copper(II) complexes, cluster 1, and mononuclear 2, have been synthesized by reacting acetylacetone and benzohydrazide (1:1 ratio for 1 and 1:2 ratio for 2) with CuCl(2) in a methanol solution. In 2, which is a new complex, the ligand acts as a tetradentate which binds the metal ion via two amide-O atoms and two imine-N atoms providing an N(2)O(2) square-planar around the copper(II) ion. The absorption spectra data evidence strongly suggested that the two copper(II) compounds could interact with CT-DNA (intrinsic binding constant, K(b) = 0.45×10(4) M-1 for 1 and K(b) = 2.39×10(4) M-1 for 2). The super coiled plasmid pBR322 DNA cleavage ability was studied with 1 and 2 in the presence and absence of H(2)O(2) as an oxidant. In both the absence and the presence of an oxidizing agent, complex 2 exhibited no nuclease activity. However, even in the absence of an oxidant, complex 1 exhibited significant DNA cleavage activity.

  4. Synthesis, characterization and crystal structures of two pentagonal-bipyramidal Fe(III) complexes with dihydrazone of 2,6-diacetylpyridine and Girard's T reagent. Anticancer properties of various metal complexes of the same ligand.

    Science.gov (United States)

    Anđelković, Katarina; Milenković, Milica R; Pevec, Andrej; Turel, Iztok; Matić, Ivana Z; Vujčić, Miroslava; Sladić, Dušan; Radanović, Dušanka; Brađan, Gabrijela; Belošević, Svetlana; Čobeljić, Božidar

    2017-09-01

    In this work synthesis, characterization and crystal structures of two isothiocyanato Fe(III) complexes with 2,2'-[2,6-pyridinediylbis(ethylidyne-1-hydrazinyl-2-ylidene)]bis[N,N,N-trimethyl-2-oxoethanaminium] dichloride (H2LCl2) ligand, with composition [FeL(NCS)2]SCN·2H2O and [FeL(NCS)2]2[Fe(H2O)(NCS)5]·4H2O, has been reported. Both iron(III) complexes possess the same pentagonal-bipyramidal complex cation, while the nature of their anions depends on mole ratio of NH4SCN and FeCl3·6H2O used in reaction. Cytotoxic activity of new Fe(III) complexes, as well as of previously synthesized isothiocyanato Co(II), Ni(II), Mn(II), Zn(II) and Cd(II) complexes with the same ligand, was tested against five human cancer cell lines (HeLa, MDA-MB-453, K562, LS174 and A549) and normal cell line MRC-5. The best activity was observed in the case of Fe(III), Co(II) and Cd(II) complexes. The investigation of potential of these complexes to induce HeLa and K562 cell cycle perturbations was also evaluated. Mechanism of cell death mode was elucidated on the basis of morphological changes of HeLa cells as well as identification of target caspases. It was established that DNA damage could be responsible for the activity of Fe(III) and Co(II) complexes. Pentagonal-bipyramidal Fe(III) complexes with dihydrazone of 2,6-diacetylpyridine and Girard's T reagent have been synthesized and characterized. Cytotoxic activity of Fe(III) complexes and Co(II), Ni(II), Mn(II), Zn(II) and Cd(II) complexes with the same ligand was tested. The best activity was observed in the case of Fe(III), Co(II) and Cd(II) complexes. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. p-halo N4-phenyl substituted thiosemicarbazones: Crystal structure, supramolecular architecture, characterization and bio-assay of their Co(III) and Ni(II) complexes

    Science.gov (United States)

    Kotian, Avinash; Kumara, Karthik; Kamat, Vinayak; Naik, Krishna; Kokare, Dhoolesh G.; Nevrekar, Anupama; Lokanath, Neratur Krishnappagowda; Revankar, Vidyanand K.

    2018-03-01

    In the present work, three potential metal ion chelating ligands, p-halo N4-phenyl substituted thiosemicarbazones are synthesized and characterized. The molecular structure of all (E)-4-(4-halophenyl)-1-(3-hydroxyiminobutan-2-ylidene) thiosemicarbazones (halo = F/Cl/Br) are determined by single crystal X-ray diffraction method. All the molecules have crystallized in monoclinic crystal system with P21/n space group. The ligands show Csbnd H⋯S and Nsbnd H⋯S intermolecular interactions, which are responsible to form the supramolecular self-assemblies through R22(8), R22(12) and R22(14) ring motifs. Hirshfeld surface analysis is carried out to explore the intermolecular interactions. A series of Co(III) and Ni(II) mononuclear transition metal complexes derived from these ligands have been synthesized and characterized by various spectro-analytical methods. The metal to ligand stoichiometry has been found to be 1:2 in all the complexes. The synthesized compounds have been investigated for their in vitro antimicrobial potencies. The compounds are found to be more active than the standard used, in the case of E. coli and A. niger. Additionally, they are also screened for their in vitro antitubercular activity.

  6. Structural and functional characterization of CSDA protein complexes involved in the modulation of fetal globin gene expression

    OpenAIRE

    Gaudino, Sara

    2009-01-01

    Impaired switching from fetal hemoglobin (HbF) to adult globin gene expression leads to hereditary persistence of fetal hemoglobin (HPFH) in adult life. This is of prime interest because elevated HbF levels ameliorate beta-thalassemia and sickle cell anemia. Fetal hemoglobin levels are regulated by complex mechanisms involving factors linked or not to the beta-globin gene locus. To search for factors putatively involved in gamma-globin gene expression, we examined the reticulocyte transcripto...

  7. Syntheses, structural characterization and spectroscopic studies of cadmium(II)-metal(II) cyanide complexes with 4-(2-aminoethyl)pyridine

    Science.gov (United States)

    Karaağaç, Dursun; Kürkçüoğlu, Güneş Süheyla; Şenyel, Mustafa; Hökelek, Tuncer

    2017-02-01

    Three new cadmium(II)-metal(II) cyanide complexes, [Cd(4aepy)2(H2O)2][Ni(CN)4] (1), [Cd(4aepy)2(H2O)2][Pd(CN)4] (2) and [Cd(4aepy)2(H2O)2][Pt(CN)4] (3) [4aepy = 4-(2-aminoethyl)pyridine], have been synthesized and characterized by elemental, thermal, FT-IR and Raman spectral analyses. The crystal structures of 1 and 2 have been determined by single crystal X-ray diffraction technique, in which they crystallize in the monoclinic system and C2/c space group. The M(II) [M(II) = Ni(II), Pd(II) and Pt(II)] ions are coordinated with the carbon atoms of the four cyanide groups in the square planar geometries and the [M(CN)4]2- ions act as counter ions. The Cd(II) ions display an N4O2 coordination sphere with a distorted octahedral geometry, the nitrogen donors belonging to four molecules of the organic 4aepy that act as unidentate ligands and two oxygen atoms from aqua ligands. 3D supramolecular structures of 1 and 2 were occurred by M⋯π and hydrogen bonding (Nsbnd H⋯N and Osbnd H⋯N) interactions. Vibrational assignments of all the observed bands were given and the spectral properties were also supported the crystal structures of the complexes. A possible decompositions of the complexes were investigated in the temperature range 30-800 °C in the static atmosphere.

  8. Structural and biochemical characterization of human PR70 in isolation and in complex with the scaffolding subunit of protein phosphatase 2A.

    Directory of Open Access Journals (Sweden)

    Rebecca Dovega

    Full Text Available Protein Phosphatase 2A (PP2A is a major Ser/Thr phosphatase involved in the regulation of various cellular processes. PP2A assembles into diverse trimeric holoenzymes, which consist of a scaffolding (A subunit, a catalytic (C subunit and various regulatory (B subunits. Here we report a 2.0 Å crystal structure of the free B''/PR70 subunit and a SAXS model of an A/PR70 complex. The crystal structure of B''/PR70 reveals a two domain elongated structure with two Ca2+ binding EF-hands. Furthermore, we have characterized the interaction of both binding partner and their calcium dependency using biophysical techniques. Ca2+ biophysical studies with Circular Dichroism showed that the two EF-hands display different affinities to Ca2+. In the absence of the catalytic C-subunit, the scaffolding A-subunit remains highly mobile and flexible even in the presence of the B''/PR70 subunit as judged by SAXS. Isothermal Titration Calorimetry studies and SAXS data support that PR70 and the A-subunit have high affinity to each other. This study provides additional knowledge about the structural basis for the function of B'' containing holoenzymes.

  9. Synthesis, characterization, crystal structure, DNA/BSA binding ability and antibacterial activity of asymmetric europium complex based on 1,10- phenanthroline

    Science.gov (United States)

    Alfi, Nafiseh; Khorasani-Motlagh, Mozhgan; Rezvani, Ali Reza; Noroozifar, Meissam; Molčanov, Krešimir

    2017-06-01

    A heteroleptic europium coordination compound formulated as [Eu(phen)2(OH2)2(Cl)2](Cl)(H2O) (phen = 1,10-phenanthroline), has been synthesized and characterized by elemental analysis, FT-IR spectroscopy, and single-crystal X-ray diffractometer. Crystal structure analysis reveals the complex is crystallized in orthorhombic system with Pca21 space group. Electronic absorption and various emission methods for investigation of the binding system of europium(III) complex to Fish Salmon deoxyribonucleic acid (FS-DNA) and Bovamin Serum Albumin (BSA) have been explored. Furthermore, the binding constants, binding sites and the corresponding thermodynamic parameters of the interaction system based on the van't Hoff equation for FS-DNA and BSA were calculated. The thermodynamic parameters reflect the exothermic nature of emission process (ΔH°DNA by non-intercalative mode which the groove binding is preferable mode. Also, the complex exhibits a brilliant antimicrobial activity in vitro against standard bacterial strains.

  10. Supramolecular complexes of Co(II), Ni(II) and Zn(II) p-hydroxybenzoates with caffeine: Synthesis, spectral characterization and crystal structure

    Science.gov (United States)

    Taşdemir, Erdal; Özbek, Füreya Elif; Sertçelik, Mustafa; Hökelek, Tuncer; Çelik, Raziye Çatak; Necefoğlu, Hacali

    2016-09-01

    Three novel complexes Co(II), Ni(II) and Zn(II) containing p-hydroxybenzoates and caffeine ligands were synthesized and characterized by elemental analysis, FT-IR and UV-vis Spectroscopy, molar conductivity and single crystal X-ray diffraction methods. The thermal properties of the synthesized complexes were investigated by TGA/DTA. The general formula of the complexes is [M(HOC6H4COO)2(H2O)4]·2(C8H10N4O2)·8H2O (where: M: Co, Ni and Zn). The IR studies showed that carboxylate groups of p-hydroxybenzoate ligands have monodentate coordination mode. The M2+ ions are octahedrally coordinated by two p-hydroxybenzoate ligands, four water molecules leading to an overall MO6 coordination environment. The medium-strength hydrogen bondings involving the uncoordinated caffeine ligands and water molecules, coordinated and uncoordinated water molecules and p-hydroxybenzoate ligands lead to three-dimensional supramolecular networks in the crystal structures.

  11. Synthesis, structural and spectroscopic characterization and biomimetic properties of new copper, manganese, zinc complexes: identification of possible superoxide-dismutase mimics bearing hydroxyl radical generating/scavenging abilities.

    Science.gov (United States)

    Lupidi, Giulio; Marchetti, Fabio; Masciocchi, Norberto; Reger, Daniel L; Tabassum, Sartaj; Astolfi, Paola; Damiani, Elisabetta; Pettinari, Claudio

    2010-08-01

    A series of Cu(II), Zn(II) and Mn(II) coordination compounds has been synthesized by reaction of the corresponding metal salts and pyrazolyl-based ligands, i.e. the neutral 1-(2-(4-((2,2,2-tri(1H-pyrazol-1-yl)ethoxy)methyl)benzyloxy)-1,1-di(1H-pyrazol-1-yl)ethyl)-1H-pyrazole {p-C(6)H(4)[CH(2)OCH(2)C(pz)(3)](2), (L(1)), and the anionic hydridotris(3-phenyl-5-methylpyrazolyl)borate (L(2))(-), bis(pyrazolyl)acetate (L(3)) and bis(3,5-dimethylpyrazolyl)acetate (L(4))(-): the species [L(1)(CuCl(2))(2)] (1), [L(1)(Cu(OAc)(2))(2)] (2), [L(1)(Zn(OAc)(2))(2)] (3), [(CuCl(L(2))(Hpz(Ph,Me))] (4), [Mn(L(3))(2)].2H(2)O, (5), [ZnCl(L(3))(imH)].MeOH [CuCl(L(4))(imH)].2H(2)O (7) have been obtained (Hpz(Ph,Me)=3-phenyl-5-methylpyrazole, imH=imidazole). Complexes 1 and 4 have been structurally characterized, also using less conventional powder diffraction methods. The superoxide scavenging activity has been characterized by indirect assays including EPR analysis. All complexes exhibit superoxide scavenging activity with IC(50) in the microM range and they protect against the oxidative action of peroxynitrite in different ways. 1, 4 and 7 exert both an anti- and pro-oxidant effect depending on their concentration as evaluated by EPR and fluorescence methods. The pro-oxidative effects are absent in Zn(II) and Mn(II) complexes. (c) 2010 Elsevier Inc. All rights reserved.

  12. Chemical, structural, and electrochemical characterization of 5 V spinel and complex layered oxide cathodes of lithium ion batteries

    Science.gov (United States)

    Tiruvannamalai Annamalai, Arun Kumar

    2007-12-01

    Lithium ion batteries have revolutionized the portable electronics market since their commercialization first by Sony Corporation in 1990. They are also being intensively pursued for electric and hybrid electric vehicle applications. Commercial lithium ion cells are currently made largely with the layered LiCoO 2 cathode. However, only 50% of the theoretical capacity of LiCoO 2 can be utilized in practical cells due to the chemical and structural instabilities at deep charge as well as safety concerns. These drawbacks together with the high cost and toxicity of Co have created enormous interest in alternative cathodes. In this regard, spinel LiMn2O4 has been investigated widely as Mn is inexpensive and environmentally benign. However, LiMn 2O4 exhibits severe capacity fade on cycling, particularly at elevated temperatures. With an aim to overcome the capacity fading problems, several cationic substitutions to give LiMn2-yMyO 4 (M = Cr, Fe, Co, Ni, and Cu) have been pursued in the literature. Among the cation-substituted systems, LiMn1.5Ni0.5O 4 has become attractive as it shows a high capacity of ˜ 130 mAh/g (theoretical capacity: 147 mAh/g) at around 4.7 V. With an aim to improve the electrochemical performance of the 5 V LiMn 1.5Ni0.5O4 spinel oxide, various cation-substituted LiMn1.5-yNi0.5-zMy+zO4 (M = Li, Mg, Fe, Co, and Zn) spinel oxides have been investigated by chemical lithium extraction. The cation-substituted LiMn1.5-yNi0.5-zM y+zO4 spinel oxides exhibit better cyclability and rate capability in the 5 V region compared to the unsubstituted LiMn1.5Ni 0.5O4 cathodes although the degree of manganese dissolution does not vary significantly. The better electrochemical properties of LiMn 1.5-yNi0.5-zMy+zO4 are found to be due to a smaller lattice parameter difference among the three cubic phases formed during the charge-discharge process. In addition, while the spinel Li1-xMn1.58Ni0.42O4 was chemically stable, the spinel Li1-xCo2O4 was found to exhibit both

  13. Complexity of Curved Glass Structures

    Science.gov (United States)

    Kosić, T.; Svetel, I.; Cekić, Z.

    2017-11-01

    Despite the increasing number of research on the architectural structures of curvilinear forms and technological and practical improvement of the glass production observed over recent years, there is still a lack of comprehensive codes and standards, recommendations and experience data linked to real-life curved glass structures applications regarding design, manufacture, use, performance and economy. However, more and more complex buildings and structures with the large areas of glass envelope geometrically complex shape are built every year. The aim of the presented research is to collect data on the existing design philosophy on curved glass structure cases. The investigation includes a survey about how architects and engineers deal with different design aspects of curved glass structures with a special focus on the design and construction process, glass types and structural and fixing systems. The current paper gives a brief overview of the survey findings.

  14. Synthesis, structural characterization and biological activities of ...

    Indian Academy of Sciences (India)

    The School of Chemical Sciences, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia e-mail: rosenani@usm.my; salambpx@yahoo.com ... complexes have been characterized by elemental analyses, UV-Vis, FT-IR, 1H, 13C and 119Sn NMR spectral studies. The molecular structure of complex 5 has been confirmed ...

  15. Synthesis and characterization of d10 metal complexes of 3-Me-5-FcPz: Structural, theoretical and third order nonlinear optical properties

    Science.gov (United States)

    Senthilkumar, Kabali; Thirumoorthy, Krishnan; Vinitha, G.; Soni, Kiran; Bhuvanesh, Nattamai S. P.; Palanisami, Nallasamy

    2017-01-01

    The d10 metal complexes based on 3-methyl-5-ferrocenyl-1H-pyrazole (L = 3-Me-5-FcPz) ligand [M(L)4(NO3)2] Zn=(1) and Cd=(2), [Hg(L)4(NO3)2].dmf (3) have been synthesized and characterized by FT-IR, NMR, UV-Vis and elemental analysis. The molecular structure of compound 2 and its crystal packing were determined by single crystal X-ray diffraction. The nitrate anions are also involved in intermolecular hydrogen bonding with adjacent ferrocene units and it forms zig-zag one-dimensional polymeric structure. UV-Vis investigations on the positive solvatochromic behavior of 1-3 revealed that the solvation of the push-pull character increases with increasing polarity. The third-order nonlinear optical (NLO) properties of 1-3 have been determined by Z-scan technique and the results indicate that compounds 1-3 exhibits the strong self-defocusing effect. The nonlinear susceptibility χ(3) values are calculated in the order of 10-6 esu.

  16. Structural and magnetic characterization of three tetranuclear Cu(II) complexes with face-sharing-dicubane/double-open-cubane like core framework

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Aparup [Department of Chemistry and Chemical Technology, Vidyasagar University, Midnapore 721102, West Bengal (India); Bertolasi, Valerio [Dipartimento di Scienze Chimiche e Farmaceutiche, Centro di Strutturistica Diffrattometrica, Università di Ferrara, Via L. Borsari, 46, 44100 Ferrara (Italy); Figuerola, Albert [Departament de Química Inorgànica i Orgànica (Secció de Química Inorgànica) and Institut de Nanociència i Nanotecnologia (IN2UB), Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona (Spain); Manna, Subal Chandra, E-mail: scmanna@mail.vidyasagar.ac.in [Department of Chemistry and Chemical Technology, Vidyasagar University, Midnapore 721102, West Bengal (India)

    2017-05-15

    } = S{sub Cu} =1/2, was used to study the magnetic behaviour of the double open cubane core of and a good agreement between the experimental and simulated results was found by using the parameters g{sub 1} = g{sub 2} =2.20, g{sub 3} = g{sub 4} =2.18, J{sub 1} =−36 cm{sup -1}, J{sub 2} =−44 cm{sup -1} and J{sub 3} =0 cm{sup -1}. - Graphical abstract: Tetranuclear Cu(II) complexes with face-sharing-dicubane / double-open-cubane like core frameworks were synthesized and characterized by crystal structure and magnetic analysis. Variable temperature magnetic properties corroborate with their structural arrangement. - Highlights: • Novel tetranuclear copper(II) complexes have been structurally characterized. • Complexes possess face-sharing dicubane/double open cubane core structures. • Variable temperature magnetic measurements reveal antiferromagnetic coupling. • PHI program was used to explain the observed magnetic properties.

  17. Characterization of complex renal cysts

    DEFF Research Database (Denmark)

    Graumann, Ole; Osther, Susanne Sloth; Osther, Palle Jörn Sloth

    2010-01-01

    Abstract Objective. Complex renal cysts represent a major clinical problem, since it is often difficult to exclude malignancy. The Bosniak classification system, based on computed tomography (CT), is widely used to categorize cystic renal lesions. The aim of this study was to evaluate critically...... available data on the Bosniak classification. Material and methods. All publications from an Entrez Pubmed search were reviewed, focusing on clinical applicability and the use of imaging modalities other than CT to categorize complex renal cysts. Results. Fifteen retrospective studies were found. Most...

  18. Synthesis, structural characterization and luminescent properties of a novel europium ternary complex Eu(2-A-4-CBA){sub 3}phen

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yongjie, E-mail: cyj200507@aliyun.com; Wu, Shengnan; Xing, Zhenfang; Cao, Shuang; Geng, Xiujuan; Yang, Ying; Xiao, Linjiu

    2015-11-15

    The preparation of a novel europium ternary complex with the formula of Eu(2-A-4-CBA){sub 3}phen (where, 2-A-4-CBA = 2-amino-4-chlorobenzoic acid, phen = 1,10-phenanthroline) under solvothermal condition is described. The composition and structure of the resulting complex were investigated by elemental analysis, Fourier transform infrared (FT-IR) spectroscopy. The complex is polycrystalline, and the morphology is clean and regular as revealed by scanning electron microscope (SEM). The luminescent and thermal properties of the complex were researched by fluorescence spectroscopy and thermogravimetric analysis, respectively. Of importance here is that, the room-temperature luminescence spectra of the complex show strong characteristic emission of the corresponding Eu{sup 3+}, which is attributed to the energy transfer from ligands to Eu{sup 3+} via an Antenna effect. It is also found that the complex exhibits pure red light and high color purity. In addition, the complex does not decompose until 300 °C, so it exhibits good thermal stability. - Highlights: • A novel Eu(III) complex was synthesized by solvothermal synthesis method. • The structure and properties of complex were studied. • The complex can emits pure red light and has a high color purity. • The complex does not decompose until 300 °C and it has a good thermal stability.

  19. Synthesis, characterization, crystal structure determination and computational study of a new Cu(II) complex of bis [2-{(E)-[2-chloroethyl)imino]methyl}phenolato)] copper(II) Schiff base complex

    Science.gov (United States)

    Grivani, Gholamhossein; Vakili, Mohammad; Khalaji, Aliakbar Dehno; Bruno, Giuseppe; Rudbari, Hadi Amiri; Taghavi, Maedeh

    2016-07-01

    The copper (II) Schiff base complex of [CuL2] (1), HL = 2-{(E)-[2-chloroethyl) imino]methyl}phenol, has been synthesized and characterized by elemental (CHN) analysis, UV-Vis and FT-IR spectroscopy. The molecular structure of 1 was determined by single crystal X-ray diffraction technique. The conformational analysis and molecular structures of CuL2 were investigated by means of density functional theory (DFT) calculations at B3LYP/6-311G* level. An excellent agreement was observed between theoretical and experimental results. The Schiff base ligand of HL acts as a chelating ligand and coordinates via one nitrogen atom and one oxygen atom to the metal center. The copper (II) center is coordinated by two nitrogen atoms and two oxygen atoms from two Schiff base ligands in an approximately square planar trans-[MN2O2] coordination geometry. Thermogravimetric analysis of CuL2 showed that it was decomposed in five stages. In addition, the CuL2 complex thermally decomposed in air at 660 °C and the XRD pattern of the obtained solid showed the formation of CuO nanoparticles with an average size of 34 nm.

  20. Thermodynamic characterization of polyhydride complexes

    Energy Technology Data Exchange (ETDEWEB)

    Zidan, R.A.; Rocheleau, R.E.; Jensen, C.M. [Univ. of Hawaii, Manoa, Honolulu, HI (United States)

    1996-10-01

    The authors have investigated the interaction of hydrogen with solid IrXH{sub 2} (PPr{sup i}{sub 3}){sub 2}(H{sub 2}) (X=Cl, I). Gaseous hydrogen was found to react directly and reversibly with solid iridium chloro-complex, IrClH{sub 2}(PPr{sup i}{sub 3}){sub 2}(H{sub 2}) under mild conditions of pressure and temperature. Equilibrium absorption and desorption isotherms were obtained at fixed temperatures ranging from 273{degrees} K to 323{degrees} K over the pressure range from 0.1 to 11 atmospheres. The rates of hydrogen uptake and release were found to be very rapid. A Gaussian shaped thermal desorption spectrum showed that hydrogen desorption occurred over a wide range of temperatures from 200{degrees} K to 350{degrees} K. The TDS results and the absence of well defined plateaus in p-c isotherms indicated a disorder of the hydrogen arrangement in the iridium complex matrix. These observation were consistent with earlier findings from NMR and neutron diffraction measurements. The enthalpy ({Delta}H) and the entropy ({Delta}S) of hydrogen desorption, from a van`t Hoffs plot based on the hydrogen pressure at 50% of full loading of hydrogen at fixed temperatures, were {minus}4.9 {+-}0.3 kcaL/mole of H{sub 2} and 28.6{+-} cal/deg. mole of H{sub 2} respectively. Hydrogen desorption from IrIH{sub 2}(PPr{sup i}{sub 3}){sub 2}(H{sub 2}) was not observed at the above temperature and pressure ranges, indicating stronger hydrogen bond in iodo-complex compared to the chloro-complex.

  1. Structural, EPR and Mössbauer Characterization of (μ-Alkoxo)(μ-Carboxylato)Diiron(II,III) Model Complexes for the Active Sites of Mixed-valent Diiron Enzymes

    Science.gov (United States)

    Li, Feifei; Chakrabarti, Mrinmoy; Dong, Yanhong; Kauffmann, Karl; Bominaar, Emile L.; Münck, Eckard; Que, Lawrence

    2012-01-01

    To obtain structural and spectroscopic models for the diiron(II,III) centers in the active sites of diiron enzymes, the (μ-alkoxo)(μ-carboxylato)diiron(II,III) complexes [FeIIFeIII(N-Et-HPTB)(O2CPh)(NCCH3)2](ClO4)3 (1) and [FeIIFeIII(N-Et-HPTB)(O2CPh) (Cl)(HOCH3)](ClO4)2 (2) (N-Et-HPTB = N,N,N′,N′-tetrakis(2-(1-ethyl-benzimidazolylmethyl))-2-hydroxy-1,3-diamino propane), have been prepared and characterized by X-ray crystallography, EPR, and Mössbauer spectroscopy. The Fe1-Fe2 separations are 3.60 Å and 3.63 Å and the Fe1-O1-Fe2 bond angles are 128.0° and 129.4° for 1 and 2, respectively. Mössbauer and EPR studies of 1 show that the FeIII (SA = 5/2) and FeII (SB = 2) sites are antiferromagnetically coupled to yield a ground state with S = 1/2 (g = 1.75, 1.88, 1.96); Mössbauer analysis of solid 1 yields J = 22.5 ± 2 cm−1 for the exchange coupling constant ( = JSA•SB convention). In addition to the S = 1/2 ground state spectrum of 1, the EPR signal for the S = 3/2 excited state of the spin ladder can also be observed, the first time such a signal has been detected for an antiferromagnetically coupled diiron(II,III) complex. The anisotropy of the 57Fe magnetic hyperfine interactions at the FeIII site is larger than normally observed in mononuclear complexes and arises from admixing S > 1/2 excited states into the S = 1/2 ground state by zero-field splittings at the two Fe sites. Analysis of the “D/J” mixing has allowed us to extract the zero-field splitting parameters, local g values, and magnetic hyperfine structural parameters for the individual Fe sites. The methodology developed and followed in this analysis is presented in detail. The spin Hamiltonian parameters of 1 are related to the molecular structure with the help of DFT calculations. Contrary to what was assumed in previous studies, our analysis demonstrates that the deviations of the g-values from the free electron value (g = 2) for the antiferromagnetically coupled diiron

  2. Synthesis of bis(oxamato) transition metal complexes and Ni nanoparticles and their structural, magnetic, optical, and magneto-optical characterization

    Energy Technology Data Exchange (ETDEWEB)

    Braeuer, Bjoern

    2008-07-02

    In the framework of this thesis mono- and oligonuclear Cu(II)- anf Ni(II)-bis(oxamato) complexes are synthesized in view on their magneto-optical properties and structurally characterized. About transition-charge and transition-metal induced deviations from the general reaction behaviour described in literature is reported. From electron-spin-resonance studies the spin-density distribution in the mononuclear Cu(II) complexes is derived. The influence on this by coordination geometry as well as the effects of the superexchange interaction are discussed and compared with results from the density functional theory (DFT). Trinuclear bis(oxamato) complexes are for the first time deposited on Si(111) substrates by spin coating and studied by means of the spectroscopic ellipsometry as well as the Raman spectroscopy and evaluated by means of DFT calculations. Magneto-optical Kerr-effect studies were performed on thin layers of these complexes as well as phthalocyanines. For the comparison the magnetic and magneto-optical properties of Ni nanoparticles in different organic matrices were studied. By means of the photoelectron spectroscopy the oxidation behaviour of these is studied and conclusions on charge-transfer processes between the matrices and the nanoparticles are drawn. [German] Im Rahmen dieser Arbeit werden ein- und mehrkernige Cu(II)- und Ni(II)-bis-(oxamato)-Komplexe im Hinblick auf ihre magneto-optischen Eigenschaften gezielt hergestellt und strukturell charakterisiert. Ueber ladungs- und uebergangsmetallinduzierte Abweichungen vom allgemeinen in der Literatur beschriebenen Reaktionsverhalten wird berichtet. Aus Elektronenspinresonanz-Untersuchungen wird die Spindichteverteilung in den einkernigen Cu(II)-Komplexen abgeleitet. Die Beeinflussung dieser durch die Koordinationsgeometrie sowie die Auswirkungen auf die Superaustausch- Wechselwirkung werden diskutiert und mit Ergebnissen der Dichtefunktionaltheorie (DFT) verglichen. Dreikernige bis

  3. Synthesis and spectra characterization of mixed ligand complexes ...

    African Journals Online (AJOL)

    The synthesized ligand and its metal complexes have been characterized by elemental analysis and spectroscopic (i.r. and electronic) methods. An octahedral geometric structure is proposed for the metal complexes. The six coordinate environment of the metals is composed of N5X core with thr ee nitrogen atoms from the ...

  4. Characterization of ternary bivalent metal complexes with bis(2-hydroxyethyl)iminotris(hydroxymethy)methane (Bis?Tris) and the comparison of five crystal structures of Bis?Tris complexes*1

    Science.gov (United States)

    Inomata, Yoshie; Gochou, Yoshihiro; Nogami, Masanobu; Howell, F. Scott; Takeuchi, Toshio

    2004-09-01

    Eleven bivalent metal complexes with bis(2-hydroxyethyl)iminotris(hydroxymethy)methane (Bis-Tris:hihm): [M(hihm)(H 2O)]SO 4· nH 2O (M: Co, Ni, Cu, Zn), [MCl(hihm)]Cl· nH 2O (M: Co, Ni, Cu), and [M(HCOO)(hihm)](HCOO) (M: Co, Ni, Cu, Zn) have been prepared and characterized by using their infrared absorption and powder diffuse reflection spectra, magnetic susceptibility, thermal analysis and powder X-ray diffraction analysis. The crystal structures of [Ni(hihm)(H 2O)]SO 4·H 2O ( 2), [Cu(hihm)(H 2O)]SO 4 ( 3), [NiCl(hihm)]Cl·H 2O ( 6), [CuCl(hihm)]Cl ( 7) and [Co(HCOO)(hihm)](HCOO) ( 8) have been determined by single crystal X-ray diffraction analysis. The crystals of [Ni(hihm)(H 2O)]SO 4·H 2O ( 2) and [Cu(hihm)(H 2O)]SO 4 ( 3) are each orthorhombic with the space group P2 12 12 1 and Pna2 1. For both complexes, the metal atom is in a distorted octahedral geometry, ligated by four hydroxyl oxygen atoms, a nitrogen atom and a water molecule. [NiCl(hihm)]Cl·H 2O ( 6) is monoclinic with the space group P2 1/ n. For complex ( 6), the nickel atom is in a distorted octahedral geometry, ligated by four hydroxyl oxygen atoms, a nitrogen atom and a chloride ion. [CuCl(hihm)]Cl ( 7) is orthorhombic with the space group P2 12 12 1. Although in this copper(II) complex the copper atom is ligated by six atoms, it is more reasonable to think that the copper atom is in a trigonal bipyramidal geometry coordinated with five atoms: three hydroxyl oxygen atoms, a nitrogen atom and a chloride ion if the bond distances and angles surrounding the copper atom are taken into consideration. [Co(HCOO)(hihm)](HCOO) ( 8) is monoclinic with the space group P2 1. In cobalt(II) complex ( 8), the cobalt atom is in a distorted octahedral geometry, ligated by four hydroxyl oxygen atoms, a nitrogen atom and an oxygen atom of a formate ion. The structure of complex ( 8) is the same as the structure of [NiCl(hihm)]Cl·H 2O ( 6) except for the formate ion coordinating instead of the chloride ion. [M

  5. Zinc (II) complexes of carboxamide derivatives: Crystal structures ...

    Indian Academy of Sciences (India)

    The two complexes were characterized by physicochemical and spectroscopic tools, and by X-ray crystal structures of both ligands and the complex 1. In complex 1, zinc(II) is chelated by three ligands with a distorted octahedral geometry. The DNA-binding properties of zinc complexes 1 and 2 have been investigated by ...

  6. Quest for Environmentally-Benign Ligands for Actinide Separations: Thermodynamic, Spectroscopic, and Structural Characterization of U(VI) Complexes with Oxa-Diamide and Related Ligands

    Energy Technology Data Exchange (ETDEWEB)

    Advanced Light Source; Tian, Guoxin; Rao, Linfeng; Teat, Simon J.; Liu, Guokui

    2009-01-05

    Complexation of U(VI) with N,N,N{prime},N{prime}-tetramethyl-3-oxa-glutaramide (TMOGA) and N,N-dimethyl-3-oxa-glutaramic acid (DMOGA) was studied in comparison with their dicarboxylate analog, oxydiacetic acid (ODA). Thermodynamic parameters, including stability constants, enthalpy and entropy of complexation, were determined by spectrophotometry, potentiometry and calorimetry. Single-crystal X-ray diffractometry, EXAFS spectroscopy, FT-IR absorption and laser-induced luminescence spectroscopy were used to obtain structural information on the U(VI) complexes. Like ODA, TMOGA and DMOGA form tridentate U(VI) complexes, with three oxygen atoms (the amide, ether and/or carboxylate oxygen) coordinating to the linear UO{sub 2}{sup 2+} cation via the equatorial plane. The stability constants, enthalpy and entropy of complexation all decrease in the order ODA > DMOGA > TMOGA, showing that the complexation is entropy driven and the substitution of a carboxylate group with an amide group reduces the strength of complexation with U(VI) due to the decrease in the entropy of complexation. The trend in the thermodynamic stability of the complexes correlates very well with the structural and spectroscopic data obtained by single crystal XRD, FT-IR and laser-induced luminescence spectroscopy.

  7. Directed synthesis of a heterobimetallic complex based on a novel unsymmetric double-Schiff-base ligand: preparation, characterization, reactivity and structures of hetero- and homobimetallic nickel(II) and zinc(II) complexes.

    Science.gov (United States)

    Roth, Arne; Buchholz, Axel; Rudolph, Manfred; Schütze, Eileen; Kothe, Erika; Plass, Winfried

    2008-01-01

    A series of bimetallic zinc(II) and nickel(II) complexes based on the novel dinucleating unsymmetric double-Schiff-base ligand benzoic acid [1-(3-{[2-(bispyridin-2-ylmethylamino)ethylimino]methyl}-2-hydroxy-5-methylphenyl)methylidene]hydrazide (H(2)bpampbh) has been synthesized and structurally characterized. The metal centers reside in two entirely different binding pockets provided by the ligand H(2)bpampbh, a planar tridentate [ONO] and a pentadentate [ON(4)] compartment. The utilized ligand H(2)bpampbh has been synthesized by condensation of the single-Schiff-base proligand Hbpahmb with benzoic acid hydrazide. The reaction of H(2)bpampbh with two equivalents of either zinc(II) or nickel(II) acetate yields the homobimetallic complexes [Zn(2)(bpampbh)(mu,eta(1)-OAc)(eta(1)-OAc)] (ZnZn) and [Ni(2)(bpampbh)(mu-H(2)O)(eta(1)-OAc)(H(2)O)](OAc) (NiNi), respectively. Simultaneous presence of one equivalent zinc(II) and one equivalent nickel(II) acetate results in the directed formation of the heterobimetallic complex [NiZn(bpampbh)(mu,eta(1)-OAc)(eta(1)-OAc)] (NiZn) with a selective binding of the nickel ions in the pentadentate ligand compartment. In addition, two homobimetallic azide-bridged complexes [Ni(2)(bpampbh)(mu,eta(1)-N(3))]ClO(4) (NiNi(N(3))) and [Ni(2)(bpampbh)(mu,eta(1)-N(3))(MeOH)(2)](ClO(4))(0.5)(N(3))(0.5) (NiNi(N(3))(MeOH)(2)) were synthesized. In all complexes, the metal ions residing in the pentadentate compartment adopt a distorted octahedral coordination geometry, whereas the metal centers placed in the tridentate compartment vary in coordination number and geometry from square-planar (NiNi(N(3))) and square-pyramidal (ZnZn and NiZn), to octahedral (NiNi and NiNi(N(3))(MeOH)(2)). In the case of complex NiNi(N(3)) this leads to a mixed-spin homodinuclear nickel(II) complex. All compounds have been characterized by means of mass spectrometry as well as IR and UV/Vis spectroscopies. Magnetic susceptibility measurements show significant zero

  8. Physicochemical Characterization of Inclusion Complex of Catechin ...

    African Journals Online (AJOL)

    Purpose: To investigate the suitability of glucosyl-β-cyclodextrin (G-β-CD) to form inclusion complex with catechin, and characterize the physicochemical properties of the inclusion complex of catechin and G-β-CD. Methods: Catechin and G-β-CD was mixed in water at the same molar ratio, stirred at 20 °C for 48 h and ...

  9. Structural characterization of 1,8-naphthalimides and in vitro microbiological activity of their Cu(II) and Zn(II) complexes

    Science.gov (United States)

    Grabchev, Ivo; Yordanova, Stanislava; Bosch, Paula; Vasileva-Tonkova, Evgenia; Kukeva, Rositsa; Stoyanov, Stanimir; Stoyanova, Radostina

    2017-02-01

    Two new 1,8-naphthalimide derivatives (NI1 and NI2) have been synthesized and characterized. The photophysical properties of the new compounds have been investigated in organic solvents of different polarity. It has been shown that both compounds are solvent depended. Cu(II) and Zn(II) complexes of NI2 were obtained and characterized by IR-NMR, fluorescence and EPR spectroscopy. The influence of different metal cations on the fluorescence intensity has been investigated in acetonitrile solution. Antimicrobial composite PLA-metal complexes materials have been obtained for the first time. Microbiological activity of both metal complexes has been investigated in vitro against different Gram-positive and Gram-negative bacteria and two yeasts. The various antimicrobial activities and the minimum inhibitory concentrations (MICs) of both complexes have been determined. The microbiological activity of composite materials PLA-metal complexes in thin polymeric film has also been investigated. The results suggest that the new metal complexes could find application in designing new antimicrobial preparations to control the spread of infections.

  10. SYNTHESIS, CHARACTERIZATION AND CRYSTAL STRUCTURE ...

    African Journals Online (AJOL)

    Preferred Customer

    The Mo atom in the complex is in octahedral coordination. Thermal stability of the complex has also been studied. KEY WORDS: Molybdenum complex, Hydrazone ligand, Crystal structure, X-ray diffraction, Thermal property. INTRODUCTION. Coordination chemistry of molybdenum(VI) has attracted considerable attention ...

  11. Structural Analysis of Complex Networks

    CERN Document Server

    Dehmer, Matthias

    2011-01-01

    Filling a gap in literature, this self-contained book presents theoretical and application-oriented results that allow for a structural exploration of complex networks. The work focuses not only on classical graph-theoretic methods, but also demonstrates the usefulness of structural graph theory as a tool for solving interdisciplinary problems. Applications to biology, chemistry, linguistics, and data analysis are emphasized. The book is suitable for a broad, interdisciplinary readership of researchers, practitioners, and graduate students in discrete mathematics, statistics, computer science,

  12. Oxidative footprinting and mass spectrometry based structural characterization of mAb 14F7-NeuGc GM3 ganglioside complex

    OpenAIRE

    Abshiru, Nebiyu Ali

    2010-01-01

    The Characterization of anti body-antigen interactions provider Crucial information on the structural basis of the specificity of binding of two antibodies Their target anti-gens. In this project, an attempt was made two characterize the binding interactions Between a monoclonal anti-body (Mab) Designated as 14F7 and NeuGc-GM3 ganglioside antigen. The 14F7 strongly recognize the ganglioside antigen Fri human melanoma and breast tumors. The crystal structure of the Fab fragment 14F7 has Been s...

  13. Synthesis, structural characterization and antioxidant/anti-inflammatory activity of pentacoordinated bis(isoselenocyanato) and bis(isothiocyanato) Cu II and Ni II complexes with Me 5dien: Crystal structure of [Cu(Me 5dien)(NCSe) 2

    Science.gov (United States)

    Georgousis, Zacharias D.; Christidis, Panayiotis C.; Hadjipavlou-Litina, Dimitra; Bolos, Christos A.

    2007-06-01

    Complexes of the general formula [M(Me 5dien)X 2] [where M = Cu II and Ni II, Me 5dien = N, N, N', N″, N″- pentamethyldiethylenetriamine and X = (SCN -) or (SeCN -)] have been synthesized and characterized by elemental analyses, infrared and electronic spectroscopy, magnetic moment and molar conductivity measurements and X-ray crystallography. The crystal structure of [Cu(Me 5dien)(NCSe) 2] revealed the tridentate coordination of Me 5dien and the N-terminal coordination of two SeCN ligands to the Cu II ion. The latter adopts a distorted square pyramidal geometry, with the basal positions occupied by the three nitrogen atoms of Me 5dien and by the nitrogen atom of one isoselenocyanate ligand. The apical position is occupied by the nitrogen atom of the second isoselenocyanate ligand. Infrared spectra of the complexes confirmed the N-terminal coordination of the pseudohalides and the tridentate coordination of the triamine. Electronic spectra were all consistent with five-coordinate square pyramidal geometries. The complexes are monomeric, paramagnetic and non-electrolytes in MeOH, but 1:1 electrolytes in DMSO. The complexes were tested for antioxidant/anti-inflammatory activity. The presence of a isoselenocyanato (NCSe) group leads to higher reducing activity in comparison to the isothiocyanato (NCS) group. The nature of the metal plays also an important role to this activity. Complex [Ni(Me 5dien)(NCSe) 2] is more potent than the corresponding copper complex and offers 44.7% protection against the carrageenin-induced rat paw edema.

  14. Synthesis, structure, electrochemistry, and spectral characterization of bis-isatin thiocarbohydrazone metal complexes and their antitumor activity against ehrlich ascites carcinoma in swiss albino mice.

    Science.gov (United States)

    Sathisha, M P; Revankar, V K; Pai, K S R

    2008-01-01

    The synthesis, structure, electrochemistry, and biological studies of Co(II), Ni(II), Cu(II), and Zn(II) complexes of thiocarbohydrazone ligand are described. The ligand is synthesized starting from thiocarbohydrazide and isatin. It is evident from the IR data that in all the complexes, only one part of the ligand is coordinated to the metal ion resulting mononuclear complexes. The ligand coordinates essentially through the carbonyl oxygen of the isatin fragment, the nitrogen atom of the azomethine group, and sulfur atom after deprotonation to give five membered rings. H1 NMR spectrum of the ligand shows only one set of signals for the aromatic protons, while the NH of isatin and NH of hydrazone give rise to two different singlets in the 11-14 ppm range. The formulations, [Cu(L)Cl].2H2O, [Cu(L)(CH3COO)].2H2O, [Ni(L)Cl], [Ni(L)(CH3COO)], [Co(L2)], and [Zn(L2)].2H2O are in accordance with elemental analyses, physical, and spectroscopic measurements. The complexes are soluble in organic solvents. Molar conductance values in DMF indicate the nonelectrolytic nature of the complexes. Copper complex displays quasireversible cyclic voltametric responses with Ep near -0.659 v and 0.504 v Vs Ag/AgCl at the scan rate of 0.1 V/s. Copper(II) complexes show a single line EPR signals. For the observed magnetic moment and electronic spectral data possible explanation has been discussed. From all the available data, the probable structures for the complexes have been proposed. The compounds synthesized in present study have shown promising cytotoxic activity when screened using the in vitro method and at the same time were shown to have good activity when tested using the Ehrlich ascites carcinoma (EAC) model. The antimicrobial screening showed that the cobalt complex possesses enhanced antimicrobial activity towards fungi.

  15. Network quotients: structural skeletons of complex systems.

    Science.gov (United States)

    Xiao, Yanghua; MacArthur, Ben D; Wang, Hui; Xiong, Momiao; Wang, Wei

    2008-10-01

    A defining feature of many large empirical networks is their intrinsic complexity. However, many networks also contain a large degree of structural repetition. An immediate question then arises: can we characterize essential network complexity while excluding structural redundancy? In this article we utilize inherent network symmetry to collapse all redundant information from a network, resulting in a coarse graining which we show to carry the essential structural information of the "parent" network. In the context of algebraic combinatorics, this coarse-graining is known as the "quotient." We systematically explore the theoretical properties of network quotients and summarize key statistics of a variety of "real-world" quotients with respect to those of their parent networks. In particular, we find that quotients can be substantially smaller than their parent networks yet typically preserve various key functional properties such as complexity (heterogeneity and hub vertices) and communication (diameter and mean geodesic distance), suggesting that quotients constitute the essential structural skeletons of their parent networks. We summarize with a discussion of potential uses of quotients in analysis of biological regulatory networks and ways in which using quotients can reduce the computational complexity of network algorithms.

  16. Structural and magnetic characterization of three tetranuclear Cu(II) complexes with face-sharing-dicubane/double-open-cubane like core framework

    Science.gov (United States)

    Paul, Aparup; Bertolasi, Valerio; Figuerola, Albert; Manna, Subal Chandra

    2017-05-01

    Three novel tetranuclear copper(II) complexes namely [Cu4(L1)4]•2(dmf) (1), [Cu4(L1)4] (2) and [Cu4(L2)2(HL2)2(H2O)2]•2(ClO4)·6(H2O) (3) (H2L1, (E)-2-((1-hydroxybutan-2-ylimino)methyl)phenol; H2L2, (E)-2-((1-hydroxybutan-2-ylimino)methyl)-6-methoxyphenol)) were synthesized from the self-assembly of copper(II) perchlorate and the tridentate Schiff base ligands. The structural determination reveals that complex 1 crystallizes in the monoclinic system with space group C2/c, whereas both the complexes 2 and 3 crystallize in the triclinic system with space group P-1. Complexes 1 and 2 possess face-sharing dicubane core, on the other hand complex 3 has double open cubane core structure. The copper(II) ions in the cubane core are in distorted square planar geometries, and weak π…π and C-H…π interactions lead to formation of a 2D supramolecular architecture for complexes 1 and 2. At room temperature complexes 1, 2 and 3, exhibit fluorescence with a quantum yield (Φs) of 0.47, 0.49 and 0.38, respectively. Variable temperature magnetic susceptibility measurements in the range 2-300 K indicate an overall weak antiferromagnetic exchange coupling in all complexes. The PHI program was used to study their magnetic behaviour. In agreement with their face-sharing dicubane structure, a Hamiltonian of the type H =- J1(S1S2+S1S2'+S1'S2+S1'S2') - J2S1S1', where S1 = S1' = S2 = S2' = SCu =1/2, was used for studying complexes 1 and 2. Simulations performed suggest magnetic exchange constants with values close to J1 =-20 cm-1 and J2 =0 cm-1 for these complexes. On the other hand, the spin Hamiltonian H =- J1(S1S4+S2S3) - J2(S1S3+S2S4) - J3S1S2, where S1 = S2 = S3 = S4 = SCu =1/2, was used to study the magnetic behaviour of the double open cubane core of complex 3 and a good agreement between the experimental and simulated results was found by using the parameters g1 = g2 =2.20, g3 = g4 =2.18, J1 =-36 cm-1, J2 =-44 cm-1 and J3 =0 cm-1.

  17. Preparation, Structure Characterization and Thermal Decomposition ...

    African Journals Online (AJOL)

    The complex was structurally characterized by single crystal X-ray diffraction, elemental analysis,UVand IR spectroscopy, molar conductance and TG-DTG techniques. ... Each Dy(III) ion is eight-coordinated to one 1,10-phenanthroline molecule, one bidentate carboxylate group and four bridging carboxylate groups.

  18. Structural and spectroscopic characterization of two new Cd(II) complexes: bis(thiosaccharinato)bis(imidazole) cadmium(II) and tris(thiosaccharinato)aquacadmate(II)

    Science.gov (United States)

    Tarulli, S. H.; Quinzani, O. V.; Baran, E. J.; Piro, O. E.; Castellano, E. E.

    2003-08-01

    The crystal structures of [Cd(tsac)2(im)2] (1) (tsac=anion of thiosaccharine; im=imidazole) and of (Him)[Cd(tsac)3(H2O)] (2) (Him=imidazolium cation) have been determined at 120 K by single crystal X-ray diffractometry. Complex 1 crystallises in the monoclinic space group P21/a with Z=4 whereas compound 2 is triclinic, space group P(-1) and Z=2. In both compounds, Cd(II) is in a distorted tetrahedral environment. In the neutral complex 1 the metal is coordinated to the S-atom of the two thiosaccharinato ligands and to the N-atom of the imidazole molecules. In the anionic complex 2, Cd(II) is coordinated to three thiosaccharinato S-atoms and to the O-atom of the water molecule. The FTIR spectra of both compounds were also recorded and briefly discussed.

  19. Structural Characterization of the Catalytic γ and Regulatory β Subunits of Phosphorylase Kinase in the Context of the Hexadecameric Enzyme Complex.

    Science.gov (United States)

    Rimmer, Mary Ashley; Nadeau, Owen W; Artigues, Antonio; Carlson, Gerald M

    2017-11-03

    In the tightly regulated glycogenolysis cascade, the breakdown of glycogen to glucose-1-phosphate, phosphorylase kinase (PhK) plays a key role in the regulating the activity of glycogen phosphorylase. PhK is a 1.3 MDa hexadecamer, with four copies each of four different subunits (α, β, γ and δ), making the study of its structure challenging. Using hydrogen-deuterium exchange, we have analyzed the regulatory β subunit and the catalytic γ subunit in the context of the intact non-activated PhK complex, to study the structure of these subunits and identify regions of surface exposure. Our data suggest that within the non-activated complex the γ subunit assumes an activated conformation and are consistent with a previous docking model of the β subunit within the cryoelectron microscopy envelope of PhK. This article is protected by copyright. All rights reserved. © 2017 The Protein Society.

  20. Characterization of DPOAE fine structure

    DEFF Research Database (Denmark)

    Reuter, Karen; Hammershøi, Dorte

    2005-01-01

    The distortion product otoacoustic emission (DPOAE) fine structure is revealed, when measuring DPOAE with a very fine frequency resolution. It is characterized by consistent maxima and minima with notches of up to 20 dB depth. The fine structure is known also from absolute hearing thresholds...

  1. Synthesis and characterization of a Schiff base Cobalt (III) complex ...

    African Journals Online (AJOL)

    Cobalt (III) tris(azido)-2-Morpholino-N-(1-(2-pyridyl)ethylidene)ethanamine complex was synthesized, characterized and evaluated for in vitro anticancer activities. The chemical structure of the compound was assessed by elemental analysis, single crystal x-ray crystallography, FT-IR and UV-Visible spectroscopy.

  2. Heteroleptic complexes of Zn(II) based on 1-(5-bromo-2-hydroxybenzylidene)-4-phenylthiosemicarbazide: Synthesis, structural characterization, theoretical studies and antibacterial activity

    Science.gov (United States)

    Azarkish, Mohammad; Akbari, Alireza; Sedaghat, Tahereh; Simpson, Jim

    2017-04-01

    Four new ternary complexes, [ZnL (2,2‧-bipy)] (1), Zn2L2(4,4‧-bipy)] (2), [ZnL(Imd)]·H2O (3) and [ZnL3(MeImd)] (4), have been synthesized from the reaction of Zn(II) acetate with 1-(5-bromo-2-hydroxybenzylidene)-4-phenylthiosemicarbazide (H2L) in the presence of a heterocyclic base, 2,2‧-bipyridine, 4,4‧-bipyridine, imidazole or 2-methylimidazole, as an auxiliary ligand. The complexes have been investigated by elemental analysis and FT-IR, UV-Vis and 1HNMR spectroscopy. These data show that the thiosemicarbazone acts as a tridentate dianionic ligand and coordinates via the thiol group, imine nitrogen, and phenolic oxygen. The coordination sphere was completed by the nitrogen atom(s) of the secondary ligand. The structure of 1 was also confirmed by X-ray crystallography and shown to be a five coordinate complex with coordination geometry between the square-pyramidal and trigonal-bipyramidal. Density functional theory (DFT) calculations including geometry optimization, vibrational frequencies and electronic absorptions have been performed for 1 with the B3LYP functional at the TZP(6-311G*) basis set using the Gaussian 03 or ADF 2009 packages. The optimization calculation showed that the crystallographically determined geometry parameters can be reproduced with that basis set. Experimental IR frequencies and calculated vibration frequencies also support each other. The in vitro antibacterial activities of the ligand and complexes have been evaluated against Gram-positive (B. subtilis and S. aureus) and Gram-negative (P. aeruginosa) bacteria and compared with the standard antibacterial drugs. The results reveal that all of the complexes show much better activity in comparison to the individual thiosemoicarbazone ligand (H2L), against all bacterial strains used, with complex 3 showing the most promising results.

  3. The structural and biochemical characterization of human RNase H2 complex reveals the molecular basis for substrate recognition and Aicardi-Goutières syndrome defects.

    Science.gov (United States)

    Figiel, Małgorzata; Chon, Hyongi; Cerritelli, Susana M; Cybulska, Magdalena; Crouch, Robert J; Nowotny, Marcin

    2011-03-25

    RNase H2 cleaves RNA sequences that are part of RNA/DNA hybrids or that are incorporated into DNA, thus, preventing genomic instability and the accumulation of aberrant nucleic acid, which in humans induces Aicardi-Goutières syndrome, a severe autoimmune disorder. The 3.1 Å crystal structure of human RNase H2 presented here allowed us to map the positions of all 29 mutations found in Aicardi-Goutières syndrome patients, several of which were not visible in the previously reported mouse RNase H2. We propose the possible effects of these mutations on the protein stability and function. Bacterial and eukaryotic RNases H2 differ in composition and substrate specificity. Bacterial RNases H2 are monomeric proteins and homologs of the eukaryotic RNases H2 catalytic subunit, which in addition possesses two accessory proteins. The eukaryotic RNase H2 heterotrimeric complex recognizes RNA/DNA hybrids and (5')RNA-DNA(3')/DNA junction hybrids as substrates with similar efficiency, whereas bacterial RNases H2 are highly specialized in the recognition of the (5')RNA-DNA(3') junction and very poorly cleave RNA/DNA hybrids in the presence of Mg(2+) ions. Using the crystal structure of the Thermotoga maritima RNase H2-substrate complex, we modeled the human RNase H2-substrate complex and verified the model by mutational analysis. Our model indicates that the difference in substrate preference stems from the different position of the crucial tyrosine residue involved in substrate binding and recognition.

  4. Mercury(II) complexes with 5-methyl-5-(4-pyridyl)-2,4-imidazolidenedione: Synthesis, structural characterization, and theoretical studies

    Science.gov (United States)

    Sabounchei, Seyyed Javad; Shahriary, Parisa; Salehzadeh, Sadegh; Gholiee, Yasin; Khavasi, Hamid Reza

    2013-11-01

    New Hg(II) complexes with 5-methyl-5-(4-pyridyl)-2,4-imidazolidenedione (L) and various halogen ions were synthesized. Based on elemental analysis and flame atomic absorption spectroscopy, complexes have general formula HgL2X2 (X = Cl- (1), Br- (2), and I- (3)). These compounds have been studied by IR, 1H and 13C NMR spectroscopy at room temperature. According to X-ray diffraction analysis, complex 2 crystallizes in monoclinic system. Hg(II) ion has been surrounded by a distorted tetrahedral arrangement of two monodentate ligands (each one coordinating by a Npyridine ring atom) and two bromine atoms. Based on crystal packing findings, intermolecular classical H-bonds of the type Nsbnd H⋯O and non-classical H-bonds of the type Csbnd H⋯O and Csbnd H⋯Br, as an important member of noncovalent interaction family, are driving forces for the formation of a very distorted structure. Theoretical studies showed that neither the size of the halide anion nor the intramolecular interactions between two ligands are the reason for the very small Nsbnd Hgsbnd N bond angle, observed in complex 2.

  5. Synthesis, structural characterization and antioxidant activity of some vanadium(IV), Mo(VI)/(IV) and Ru(II) complexes of pyridoxal Schiff base derivatives

    Science.gov (United States)

    Elsayed, Shadia A.; Noufal, Aya M.; El-Hendawy, Ahmed M.

    2017-09-01

    New complexes containing vanadium(IV), Mo(VI)/(IV) and Ru(II) derived from Schiff base of pyridoxal and S-benzyldithiocarbazate (H2pysb) or p-toluidine (Hpytol) have been prepared. The structures of the described compounds were elucidated by elemental analyses, spectroscopic techniques (IR, 1H NMR, UV-Vis and EPR) magnetism, molar conductivity and thermal analysis measurements. Their redox behaviors were also studied by cyclic voltammetry. The ligand H2pysb showed coordination to the metal ions in a dibasic tridenate manner through deprotonated phenolate oxygen, azomethine nitrogen and thiolate sulfur, while Hpytol behaved as monobasic bidentate through phenolate oxygen and azomethine nitrogen. The complexes were tested for their antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and the data obtained revealed that the scavenging activity of the complexes towards DPPH is high for the oxovanadium(IV) complexes with lower IC50 values which are comparable to ascorbic acid as a standard antioxidant. The EC50 concentration ratio together with other antioxidant parameters are also reported.

  6. A new insight into the three-dimensional architecture of the Golgi complex: Characterization of unusual structures in epididymal principal cells.

    Science.gov (United States)

    Martínez-Martínez, Narcisa; Martínez-Alonso, Emma; Tomás, Mónica; Neumüller, Josef; Pavelka, Margit; Martínez-Menárguez, José A

    2017-01-01

    Principal epididymal cells have one of the largest and more developed Golgi complex of mammalian cells. In the present study, we have used this cell as model for the study of the three-dimensional architecture of the Golgi complex of highly secretory and endocytic cells. Electron tomography demonstrated the presence in this cell type of some unknown or very unusual Golgi structures such as branched cisternae, pocket-like cisternal invaginations or tubular connections. In addition, we have used this methodology and immunoelectron microscopy to analyze the close relationship between this organelle and both the endoplasmic reticulum and microtubules, and to describe in detail how these elements interact with compact and non-compact regions of the ribbon.

  7. Synthesis, structural characterization, and photophysical properties of palladium and platinum(II) complexes containing 7,8-benzoquinolinate and various phosphine ligands.

    Science.gov (United States)

    Díez, Alvaro; Forniés, Juan; García, Ana; Lalinde, Elena; Moreno, M Teresa

    2005-04-04

    A series of mononuclear cyclometalated benzo[h]quinolinate platinum and palladium(II) complexes with phosphine ligands, namely, [M(bzq)ClL] (L=PPh2H, Pt 1, Pd 2; PPh2CCPh, Pt 3, Pd 4), [Pt(bzq)(PPh2H)(PPh2CCPh)]ClO4 5, [Pt(bzq)(PPh2C(Ph)=C(H)PPh2)]ClO4 6, and [Pt(bzq)(CCPh)(PPh2CCPh)] (7a, 7b), were synthesized. The X-ray crystal structures of 1, 6.CH3COCH3.1/2CH3(CH2)4CH3, and 7b.CH3COCH3 have been determined. In 1, the metalated carbon atom and the P atom are mutually cis, whereas in 7b they are trans located. For complex 6, C and N are crystallographically indistinguishable. Reaction of [Pt(bzq)(mu-Cl)]2 with PPh2H and excess of NEt3 leads to the phosphide-bridge platinum dimer [Pt(bzq)(mu-PPh2)]2 8 (X-ray). Moderate pi-pi intermolecular interactions and no evident Pt-Pt interactions are found in 1, 7b, and in 8. All of the complexes exhibit absorption bands at high energy due to the intraligand transitions (1IL pi --> pi) and absorptions at lower energy which are attributed to MLCT (5d) pi --> pi (CLambdaN) transition. Platinum complexes show strong luminescence in both solid state and frozen solutions. The influence of the coligands on the photophysics of the platinum complexes has been examined by absorption and emission spectroscopy.

  8. A Hirshfeld surface analysis, synthesis, structure and characterization of a new Ni(II) diamagnetic complex with the bidentate ligand homopiperazine

    Science.gov (United States)

    Klai, Kacem; Kaabi, Kamel; Jelsch, Christian; Wenger, Emmanuel; Lefebvre, Frédéric; Ben Nasr, Cherif

    2017-11-01

    A new Ni(II) complex with the bidentate ligand homopiperazine, [Ni(C5H12N2)2](CH3COO)2.4H2O, has been prepared and characterized by single crystal X-ray diffraction, elemental analysis and IR spectroscopy. The basic coordination patterns of the homopiperazine coordinated metal cations are slightly distorted square planar. In the atomic arrangement, the cationic complexes [Ni(C5H12N2)2]2+ are interconnected by the CH3COO-anions via Nsbnd H⋯O and Csbnd H⋯O hydrogen bonds to form layers parallel to the (a, b) plane. These layers are connected by hydrogen bonds generated with water molecules to build a three dimensional network. The charge density of the compound could be refined from X-ray diffraction data measured at cryogenic temperature. Intermolecular interactions were investigated by Hirshfeld surfaces. The title compound is diamagnetic as confirmed by theoretical calculations, allowing its 13C and 15N solid-state NMR spectra to be recorded. Absorption bands were identified by infrared spectroscopy. Electronic properties such as HOMO and LUMO energies were also obtained.

  9. The Structural and Biochemical Characterization of Human RNase H2 Complex Reveals the Molecular Basis for Substrate Recognition and Aicardi-Goutières Syndrome Defects*

    Science.gov (United States)

    Figiel, Małgorzata; Chon, Hyongi; Cerritelli, Susana M.; Cybulska, Magdalena; Crouch, Robert J.; Nowotny, Marcin

    2011-01-01

    RNase H2 cleaves RNA sequences that are part of RNA/DNA hybrids or that are incorporated into DNA, thus, preventing genomic instability and the accumulation of aberrant nucleic acid, which in humans induces Aicardi-Goutières syndrome, a severe autoimmune disorder. The 3.1 Å crystal structure of human RNase H2 presented here allowed us to map the positions of all 29 mutations found in Aicardi-Goutières syndrome patients, several of which were not visible in the previously reported mouse RNase H2. We propose the possible effects of these mutations on the protein stability and function. Bacterial and eukaryotic RNases H2 differ in composition and substrate specificity. Bacterial RNases H2 are monomeric proteins and homologs of the eukaryotic RNases H2 catalytic subunit, which in addition possesses two accessory proteins. The eukaryotic RNase H2 heterotrimeric complex recognizes RNA/DNA hybrids and (5′)RNA-DNA(3′)/DNA junction hybrids as substrates with similar efficiency, whereas bacterial RNases H2 are highly specialized in the recognition of the (5′)RNA-DNA(3′) junction and very poorly cleave RNA/DNA hybrids in the presence of Mg2+ ions. Using the crystal structure of the Thermotoga maritima RNase H2-substrate complex, we modeled the human RNase H2-substrate complex and verified the model by mutational analysis. Our model indicates that the difference in substrate preference stems from the different position of the crucial tyrosine residue involved in substrate binding and recognition. PMID:21177858

  10. New diorganotin(IV) complexes with 3-(2-hydroxy-5-methylphenylamino)-1,3-diphenylprop-2-en-1-one: Synthesis, spectroscopic characterization, structural studies and antibacterial activity

    Science.gov (United States)

    Sedaghat, Tahereh; Naseh, Mohamad; Bruno, Giuseppe; Amiri Rudbari, Hadi; Motamedi, Hossein

    2012-10-01

    New organotin(IV) complexes, Ph2SnL (1) and Me2SnL (2), have been synthesized from reaction of corresponding diorganotin(IV) dichlorides with a Schiff base, 3-(2-hydroxy-5-methylphenylamino)-1,3-diphenylprop-2-en-1-one (H2L), derived from condensation of 2-amino-4-methylphenol with dibenzoylmethane. The synthesized compounds have been investigated by elemental analysis and IR, 1H NMR, and 119Sn NMR spectroscopy. Spectroscopic studies show that the Schiff base acts as a tridentate dianionic ligand and coordinates via the nitrogen and phenolic and enolic oxygen atoms. The structures of H2L and 2 have been also confirmed by X-ray crystallography. Schiff base exists as the keto-amine tautomeric form in solid state with two intramolecular hydrogen bonds of the Nsbnd H⋯O type and also intermolecular hydrogen bonds of Osbnd H⋯O type that create a dimer. In the structure of 2, tin center is surrounded by two O and one N atoms from the ligand and two C atoms of methyl groups and the sixth coordination site is occupied by phenolic oxygen atom of another molecule, thus a dimeric molecule with a Sn2O2 four-membered ring is formed. The in vitro antibacterial activity of ligand and complexes has been evaluated against Gram-positive (Bacillus cereus and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. H2L showed no activity but the diphenyltin(IV) complex exhibited good activities along with the standard antibacterial drugs.

  11. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

    Structural characterization of electrodeposited boron was carried out by using transmission electron microscopy and Raman spectroscopy. Electron diffraction and phase contrast imaging were carried out by using transmission electron microscopy. Phase identification was done based on the analysis of electron diffraction ...

  12. CHEMICAL AND STRUCTURAL CHARACTERIZATION OF ...

    African Journals Online (AJOL)

    a

    *Corresponding author. E-mail: tchangbedji@hotmail.com. CHEMICAL AND STRUCTURAL CHARACTERIZATION OF NATURAL. PHOSPHATE OF HAHOTOE (TOGO). Gado Tchangbeddji1*, Gnande Djeteli1, Koffi Ani Kili1, Jean Michel Savariault2 and. Jean Louis Lacout3. 1Laboratoire de Physico-Chimie des Matériaux, ...

  13. Structural characterization of electrodeposited boron

    Indian Academy of Sciences (India)

    Abstract. Structural characterization of electrodeposited boron was carried out by using transmission electron microscopy and Raman spectroscopy. Electron diffraction and phase contrast imaging were carried out by using transmission electron microscopy. Phase identification was done based on the analysis of electron ...

  14. Synthesis and spectral characterization of mono- and binuclear copper(II) complexes derived from 2-benzoylpyridine-N⁴-methyl-3-thiosemicarbazone: crystal structure of a novel sulfur bridged copper(II) box-dimer.

    Science.gov (United States)

    Jayakumar, K; Sithambaresan, M; Aiswarya, N; Kurup, M R Prathapachandra

    2015-03-15

    Mononuclear and binuclear copper(II) complexes of 2-benzoylpyridine-N(4)-methyl thiosemicarbazone (HL) were prepared and characterized by a variety of spectroscopic techniques. Structural evidence for the novel sulfur bridged copper(II) iodo binuclear complex is obtained by single crystal X-ray diffraction analysis. The complex [Cu2L2I2], a non-centrosymmetric box dimer, crystallizes in monoclinic C2/c space group and it was found to have distorted square pyramidal geometry (Addison parameter, τ=0.238) with the square basal plane occupied by the thiosemicarbazone moiety and iodine atom whereas the sulfur atom from the other coordinated thiosemicarbazone moiety occupies the apical position. This is the first crystallographically studied system having non-centrosymmetrical entities bridged via thiolate S atoms with Cu(II)I bond. The tridentate thiosemicarbazone coordinates in mono deprotonated thionic tautomeric form in all complexes except in sulfato complex, [Cu(HL)(SO4)]·H2O (1) where it binds to the metal centre in neutral form. The magnetic moment values and the EPR spectral studies reflect the binuclearity of some of the complexes. The spin Hamiltonian and bonding parameters are calculated based on EPR studies. In all the complexes g||>g⊥>2.0023 and the g values in frozen DMF are consistent with the d(x2-y2) ground state. The thermal stabilities of some of the complexes were also determined. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Synthesis and spectral characterization of mono- and binuclear copper(II) complexes derived from 2-benzoylpyridine-N4-methyl-3-thiosemicarbazone: Crystal structure of a novel sulfur bridged copper(II) box-dimer

    Science.gov (United States)

    Jayakumar, K.; Sithambaresan, M.; Aiswarya, N.; Kurup, M. R. Prathapachandra

    2015-03-01

    Mononuclear and binuclear copper(II) complexes of 2-benzoylpyridine-N4-methyl thiosemicarbazone (HL) were prepared and characterized by a variety of spectroscopic techniques. Structural evidence for the novel sulfur bridged copper(II) iodo binuclear complex is obtained by single crystal X-ray diffraction analysis. The complex [Cu2L2I2], a non-centrosymmetric box dimer, crystallizes in monoclinic C2/c space group and it was found to have distorted square pyramidal geometry (Addison parameter, τ = 0.238) with the square basal plane occupied by the thiosemicarbazone moiety and iodine atom whereas the sulfur atom from the other coordinated thiosemicarbazone moiety occupies the apical position. This is the first crystallographically studied system having non-centrosymmetrical entities bridged via thiolate S atoms with Cu(II)sbnd I bond. The tridentate thiosemicarbazone coordinates in mono deprotonated thionic tautomeric form in all complexes except in sulfato complex, [Cu(HL)(SO4)]·H2O (1) where it binds to the metal centre in neutral form. The magnetic moment values and the EPR spectral studies reflect the binuclearity of some of the complexes. The spin Hamiltonian and bonding parameters are calculated based on EPR studies. In all the complexes g|| > g⊥ > 2.0023 and the g values in frozen DMF are consistent with the dx2-y2 ground state. The thermal stabilities of some of the complexes were also determined.

  16. Inorganic-metalorganic hybrids based on copper(II)-monosubstituted Keggin polyanions and dinuclear copper(II)-oxalate complexes. Synthesis, X-ray structural characterization, and magnetic properties.

    Science.gov (United States)

    Reinoso, Santiago; Vitoria, Pablo; Gutiérrez-Zorrilla, Juan M; Lezama, Luis; San Felices, Leire; Beitia, Javier I

    2005-12-26

    Reaction of in situ generated copper(II)-monosubstituted Keggin polyoxometalates and copper(II)-bipyridine-oxalate complexes in the corresponding alkaline acetate buffer led to the formation of hybrid metal organic-inorganic compounds K(2)[{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(H(2)O)(2)(mu-ox)}(2)].14H(2)O (1), K(14)[{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(mu-ox)}](2)[SiW(11)O(39)Cu(H(2)O)].55H(2)O (2), (NH(4))(4)[{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(mu-ox)}].10H(2)O (3), and Rb(4)[{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(mu-ox)}].10H(2)O (4). Their structures have been established by single-crystal X-ray diffraction. The main structural feature of these compounds is the presence of copper(II)-monosubstituted alpha-Keggin polyoxoanions as inorganic building blocks, on which the mu-oxalatodicopper metalorganic blocks are supported. Compound 1contains the discrete hybrid polyanion [{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(H(2)O)(2)(mu-ox)}(2)](2)(-), whereas the polymeric hybrid polyanion [{SiW(11)O(39)Cu(H(2)O)}{Cu(2)(bpy)(2)(mu-ox)}(2)](n)(4)(n)(-) gives a monodimensional character to compounds 2-4. Magnetic and EPR results are discussed with respect to the crystal structure of the compounds. DFT calculations on both the [Cu(2)(bpy)(2)(H(2)O)(4)(mu-ox)](2+) cationic complex and the metalorganic blocks have been performed in order to determine the optimized geometry and the magnetic coupling constants, respectively.

  17. Crystal structure and solution characterization of the thioredoxin-2 from Plasmodium falciparum, a constituent of an essential parasitic protein export complex.

    Science.gov (United States)

    Peng, Mindy; Cascio, Duilio; Egea, Pascal F

    2015-01-02

    Survival of the malaria parasite Plasmodium falciparum when it infects red blood cells depends upon its ability to export hundreds of its proteins beyond an encasing vacuole. Protein export is mediated by a parasite-derived protein complex, the Plasmodium translocon of exported proteins (PTEX), and requires unfolding of the different cargos prior to their translocation across the vacuolar membrane. Unfolding is performed by the AAA+protein unfoldase HSP101/ClpB2 and the thioredoxin-2 enzyme (TRX2). Protein trafficking is dramatically impaired in parasites with defective HSP101 or lacking TRX2. These two PTEX subunits drive export and are targets for the design of a novel class of antimalarials: protein export inhibitors. To rationalize inhibitor design, we solved the crystal structure of Pfal-TRX2 at 2.2-Å resolution. Within the asymmetric unit, the three different copies of this protein disulfide reductase sample its two redox catalytic states. Size exclusion chromatography and small-angle X-ray scattering (SAXS) analyses demonstrate that Pfal-TRX2 is monomeric in solution. A non-conserved N-terminal extension precedes the canonical thioredoxin-fold; although it is not observed in our structure, our solution analysis suggests it is flexible in contrast to Plasmodium thioredoxin-1. This represents a first step towards the reconstitution of the entire PTEX for mechanistic and structural studies. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. Synthesis, characterization, and reactivity of alkyldisulfanido zinc complexes.

    Science.gov (United States)

    Galardon, Erwan; Tomas, Alain; Selkti, Mohamed; Roussel, Pascal; Artaud, Isabelle

    2009-07-06

    The alkyldisulfanido zinc complexes Tp(iPr,iPr)Zn(SSR) and Tp(Ph,Me)Zn(SSR) where Tp(iPr,iPr) is hydridotris-((3,5-isopropyl)pyrazolyl)borate, Tp(Ph,Me) is hydridotris-((3-phenyl,5-methyl)pyrazolyl)borate, and (SSR) is tert-butyldisulfanido or triphenylmethanedisulfanido were synthesized by reaction between the corresponding hydroxo complexes TpZn(OH) and the synthetic persulfide RSSH. All the complexes were characterized by elemental analysis and (1)H NMR spectroscopy, and representative members of the class were also structurally characterized. The reactivity of the alkyldisulfanido TpZn(SSR) complexes with thiols was studied. In the absence of base, a simple exchange reaction between the alkyldisulfanido ligand and the thiol was observed in dichloromethane; when in the presence of base, the corresponding hydrogen(sulfido) complexes TpZn(SH) were obtained. The mechanism of the latter reaction has been studied and does not involve the coordinated alkyldisulfanido group. Reaction of the hydrogen(sulfido) complexes Tp(iPr,iPr)Zn(SH) with the thiosulfonate PhCH(2)S-SO(2)CF(3) did not yield the expected alkyldisulfanido complex but benzyltrisulfide and a new complex tentatively assigned as Tp(iPr,iPr)Zn(O(2)SCF(3)).

  19. Metal complexes of Schiff base: Preparation, characterization and antibacterial activity

    Directory of Open Access Journals (Sweden)

    Emad Yousif

    2017-05-01

    Full Text Available A total of five new metal complex derivatives of 2N-salicylidene-5-(p-nitro phenyl-1,3,4-thiadiazole, HL with the metal ions Vo(II, Co(II, Rh(III, Pd(II and Au(III have been successfully prepared in alcoholic medium. The complexes obtained are characterized quantitatively and qualitatively by using micro elemental analysis, FTIR spectroscopy, UV–Vis spectroscopy, mass spectroscopy, 1H & 13C NMR, magnetic susceptibility and conductivity measurements. From the spectral study, all the complexes obtained as monomeric structure and the metals center moieties are four-coordinated with square planar geometry except VO(II and Co complexes which existed as a square pyramidal and tetrahedral geometry respectively. The preliminary in vitro antibacterial screening activity revealed that complexes 1–5 showed moderate activity against tested bacterial strains and slightly higher compared to the ligand, HL.

  20. Synthesis, structural and spectroscopic characterization, in vitro cytotoxicity and in vivo activity as free radical scavengers of chlorido(p-cymene) complexes of ruthenium(II) containing N-alkylphenothiazines.

    Science.gov (United States)

    Krstić, Milena; Sovilj, Sofija P; Grgurić-Šipka, Sanja; Evans, Ivana Radosavljević; Borozan, Sunčica; Santibanez, Juan Francisco

    2011-09-01

    Three new ruthenium(II) complexes 1-3 containing N-alkylphenothiazine molecules were synthesized by reaction of [RuCl(2)(η(6)-p-cymene)](2) with chlorpromazine hydrochloride (1), trifluoperazine dihydrochloride (2) or thioridazine hydrochloride (3). The compounds of the general formula L[RuCl(3)(η(6)-p-cymene)] were characterized by elemental analysis and spectroscopic methods (FT-IR, UV-Vis, (1)H and (13)C NMR). Complex 2 was structurally characterized by single crystal X-ray diffraction. In vitro cytotoxic activity of complexes 1-3 were assayed in four human carcinoma cell lines MCF-7, MDA-MB-453 (breast carcinoma), SW-480 (colon carcinoma) and IM9 (myeloma multiple cells). The highest cytotoxicity (12.1 ≤ IC(50) ≤ 17.3 μM) and induced a total (SW-480) or almost total cell death (MCF-7, MDA-MB-453) at 25 μM in 48 h of treatment were observed for complex 2. The influence of three different doses (0.4, 4.5 and 90.4 μM/kg bw) of complex 2 on activities of antioxidants enzymes (superoxide dismutase (SOD) and catalase (CAT)) and lactate dehydrogenase (LDH) were investigated under physiological conditions. The effects on nitrite production (NO(2)(-)) and level of erythrocytes malondialdehyde (MDA) in rats blood were evaluated, too. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  1. Synthesis, characterization, X-ray crystal structures and antibacterial activities of Schiff base ligands derived from allylamine and their vanadium(IV), cobalt(III), nickel(II), copper(II), zinc(II) and palladium(II) complexes

    Science.gov (United States)

    Amiri Rudbari, Hadi; Iravani, Mohammad Reza; Moazam, Vahid; Askari, Banafshe; Khorshidifard, Mahsa; Habibi, Neda; Bruno, Giuseppe

    2016-12-01

    A new Schiff base ligand, HL2, and four new Schiff base complexes, NiL12, PdL12, NiL22 and ZnL22, have been prepared and characterized by elemental analysis (CHN), FT-IR and UV-Vis spectroscopy. 1H and 13C NMR techniques were employed for characterization of the ligand (HL2) and the diamagnetic complexes (PdL12 and ZnL22). The molecular structures of PdL12, NiL22 and ZnL22 complexes were determined by the single crystal X-ray diffraction technique. The crystallographic data reveal that in these complexes the metal centers are four-coordinated by two phenolate oxygen and two imine nitrogen atoms of two Schiff base ligands. The geometry around the metal center in the PdL12 and NiL22 complexes is square-planar and for ZnL22 it is a distorted tetrahedral.In the end, five new (HL2, NiL12, PdL12, NiL22 and ZnL22) and six reported (HL1, VOL12, CoL13, CuL12, ZnL12 and Zn2L14) Schiff base compounds were tested for their in vitro antimicrobial activity against Staphylococcus aureus and Escherichia coli as examples of Gram-positive and Gram-negative bacterial strains, respectively, by disc diffusion method.

  2. Copolymerization of Carbon Dioxide with Epoxides Catalyzed by Structurally Well-Characterized Dinickel Bis(benzotriazole iminophenolate) Complexes: Influence of Carboxylate Ligands on the Catalytic Performance.

    Science.gov (United States)

    Huang, Li-Shin; Tsai, Chen-Yen; Chuang, Hui-Ju; Ko, Bao-Tsan

    2017-06-05

    A series of structurally well-defined dinickel carboxylate complexes based on the (R)BiIBTP derivatives [(R)BiIBTP = bis(benzotriazole iminophenolate), where R = 3C for the propyl-bridged backbone and 5C for the 2,2-dimethyl-1,3-propyl-bridged backbone] were synthesized and developed for copolymerization of CO2 and epoxides. The one-pot reactions of nickel perchlorate with the (R)BiIBTP-H2 proligands and an appropriate amount of carboxylic acid derivatives (CF3COOH or 4-X-C6H4CO2H; X = H, CF3, OMe) upon the addition of triethylamine in refluxing methanol (MeOH) afforded dinuclear nickel dicarboxylate complexes, which could be formulated as either [((R)BiIBTP)Ni2(O2CCF3)2] (1 and 2) or [((R)BiIBTP)Ni2(O2CC6H4-4-X)2] (3-7). The dinickel monobenzoate complexes [((R)BiIBTP)Ni2(O2CPh)(ClO4)(H2O)] [R = 3C (8) and 5C (9)] were prepared by using a similar synthetic route in tetrahydrofuran under reflux with a ligand precursor to metal salt to benzoic acid ratio of 1:2:1 in the presence of NEt3. Recrystallization of neutral nickel perchlorate complex 8 in a saturated MeOH or ethanol (EtOH) solution gave ionic and alcohol-solvated monobenzoate bimetallic analogues [((3C)BiIBTP)Ni2(O2CPh)(S)2]ClO4, where S = MeOH (10) and EtOH (11). Single-crystal X-ray crystallography of dinickel analogues 1-11 indicates that the BiIBTP scaffold performs as a N,O,N,N,O,N-hexadentate ligand to chelate two Ni atoms, and the ancillary carboxylate group adopts a bridging bidentate bonding mode. Catalysis for copolymerization of carbon dioxide (CO2) with cyclohexene oxide (CHO) by complexes 1-9 was systematically investigated, and the influence of carboxylate ligands on the catalytic behavior was also studied. Trifluoroacetate-ligated dinickel complex 1 efficiently catalyzed CO2 and CHO with a high turnover frequency (>430 h(-1)) in a controlled fashion, generating perfectly alternating poly(cyclohexenecarbonate) with large molecular weight (Mn > 50000 g/mol). In addition to CO2/CHO

  3. Five-Coordinate Zinc(II Complex: Synthesis, Characterization, Molecular Structure, and Antibacterial Activities of Bis-[(E-2-hydroxy-N′-{1-(4-methoxyphenylethylidene}benzohydrazido]dimethylsulfoxidezinc(II Complex

    Directory of Open Access Journals (Sweden)

    Zhi-Qiang Liu

    2017-01-01

    Full Text Available The titled Zn(II complex was synthesized by reacting the compound (E-2-hydroxy-N′-{1-(4-methoxyphenylethylidene}benzohydrazide with zinc(II acetate dihydrate in alkaline DMSO and ethanol solution under reflux condition for 28 hours. The resulting solid was filtered and recrystallized from the mixture of ethanol and DMSO. The hydrazone Schiff base and its Zn(II complex were characterized using 1H, 13C NMR, FTIR, UV-Vis spectroscopy, and single crystal X-ray diffraction analysis. Meanwhile, their antibacterial activities were examined using disc diffusion method. The spectral studies showed that the hydrazone Schiff base underwent keto-enol tautomerization, forming a bidentate ligand (N,O towards Zn(II ion. Surprisingly, on top of the two hydrazone Schiff base molecules which coordinated to the Zn metal center, an additional DMSO molecule was found attached to the Zn metal center in the crystal data, resulting in a 5-coordinate distorted trigonal bipyramidal Zn(II complex. Both hydrazone Schiff base and its Zn(II complexes were found to exhibit low antibacterial activity even when the concentrations were increased to 800 ppm.

  4. Non-covalent interactions in 2-methylimidazolium copper(II) complex (MeImH)2[Cu(pfbz)4]: Synthesis, characterization, single crystal X-ray structure and packing analysis

    Science.gov (United States)

    Sharma, Raj Pal; Saini, Anju; Kumar, Santosh; Kumar, Jitendra; Sathishkumar, Ranganathan; Venugopalan, Paloth

    2017-01-01

    A new anionic copper(II) complex, (MeImH)2 [Cu(pfbz)4] (1) where, MeImH = 2-methylimidazolium and pfbz = pentafluorobenzoate has been isolated by reacting copper(II) sulfate pentahydrate, pentafluorobenzoic acid and 2-methylimidazole in ethanol: water mixture in 1:2:2 molar ratio. This complex 1 has been characterized by elemental analysis, thermogravimetric analysis, spectroscopic techniques (UV-Vis, FT-IR) and conductance measurements. The complex salt crystallizes in monoclinic crystal system with space group C2/c. Single crystal X-ray structure determination revealed the presence of discrete ions: [Cu(pfbz)4]2- anion and two 2-methylimidazolium cation (C4H7N2)+. The crystal lattice is stabilized by strong hydrogen bonding and F⋯F interactions between cationic-anionic and the anionic-anionic moieties respectively, besides π-π interactions.

  5. Synthesis, spectroscopic characterization and structural investigation of a new charge transfer complex of 2,6-diaminopyridine with 4-nitrophenylacetic acid: Antimicrobial, DNA binding/cleavage and antioxidant studies

    Science.gov (United States)

    Murugesan, Venkatesan; Saravanabhavan, Munusamy; Sekar, Marimuthu

    2015-08-01

    A new hydrogen-bonded charge-transfer complex (CT) formed by the reaction between donor, 2,6-diaminopyridine and acceptor, 4-nitrophenylacetic acid in methanol at room temperature. The crystal was characterized by elemental analysis, IR, NMR spectroscopic studies and thermal studies. The elemental analysis of CT complex, obtained data revealed that the formation of 1:1 ratio CT complex was proposed. Infrared and NMR studies confirm the chemical constituents and molecular structure of the synthesized complex crystal. The high thermal stability is due to the molecular frame work through H-bonding interactions. Structural investigation indicates that cation and anion are linked through strong N+-H⋯O- type of hydrogen bond. The hydrogen bonded charge transfer crystal was screened for its pharmacology, such as antimicrobial, DNA binding/cleavage and antioxidant studies. The CT complex was screened for its antibacterial and antifungal activity against various bacterial and fungal species, which shows good antimicrobial activity. The DNA binding results indicated that the compound could interact with DNA through intercalation. It should have weak to moderate capacity of scavenging with DPPH.

  6. Polymeric Cd(II), trinuclear and mononuclear Ni(II) complexes of 5-methyl-4-phenyl-1,2,4-triazole-3-thione: Synthesis, structural characterization, thermal behaviour, fluorescence properties and antibacterial activity

    Science.gov (United States)

    Bharty, M. K.; Paswan, S.; Dani, R. K.; Singh, N. K.; Sharma, V. K.; Kharwar, R. N.; Butcher, R. J.

    2017-02-01

    Syntheses of a polymeric Cd(II) complex, [Cd(mptt)2]n (1), a trinuclear Ni(II) complex, [Ni3(μ-mptt)4(μ-H2O)2(H2O)2(ttfa)2]·3H2O (2) and a mononuclear Ni(II) complex [Ni(mptt)2(en)2] (3) have been performed using the ligand 5-methyl-4-phenyl-1,2,4-triazole-3-thione (Hmptt) and nickel(II)/cadmium(II) salts {ttfa = thenoyltrifluroacetonate). The ligand and the complexes have been characterized by various physicochemical methods in addition to their single crystal X-ray structure. The Cd centre in complex 1 adopts a distorted tetrahedral geometry with one sulfur atom and two mptt ligands provide three nitrogen atoms from three triazole units. The sulfur atom of the ligand binds covalently and overall the ligand acts as uninigative N,S/N,N bidentate moiety. The polymeric structure of complex 1 results from the N atoms of the neighboring triazole units coordinating with the Cd(II) centre. The three Ni(II) centres in the trinuclear Ni(II) complex 2 form a linear arrangement and all have six coordinated arrangements. The middle Ni(II) binds with four deprotonated triazole ring nitrogens and two water molecules form two bridges. The terminal Ni(II) centres bind through two thenoyl oxygens, two triazole nitrogens and water molecules that formed bridges with the middle Ni centre. In complex 3, the nickel(II) centre is covalently bonded through two deprotonated triazole ring nitrogens from two ligand moieties and other four sites are occupied by four nitrogens from two bidentate en ligands. Thermogravimetric analyses (TGA) of the complexes indicated for NiO as the final residue. The bioefficacy of the ligand and complexes 2 and 3 have been examined against the growth of bacteria to evaluate their anti-microbial potential. Complex 2 showed high antibacterial activity as compared to the ligand and complex 3. Complexes 1, 2 and 3 are fluorescent materials with maximum emissions at 425, 421 and 396 nm at an excitation wavelength of 323, 348 and 322 nm, respectively.

  7. Topological Characterization of Complex Systems: Using Persistent Entropy

    Directory of Open Access Journals (Sweden)

    Emanuela Merelli

    2015-10-01

    Full Text Available In this paper, we propose a methodology for deriving a model of a complex system by exploiting the information extracted from topological data analysis. Central to our approach is the S[B] paradigm in which a complex system is represented by a two-level model. One level, the structural S one, is derived using the newly-introduced quantitative concept of persistent entropy, and it is described by a persistent entropy automaton. The other level, the behavioral B one, is characterized by a network of interacting computational agents. The presented methodology is applied to a real case study, the idiotypic network of the mammalian immune system.

  8. Eight and nine-coordinate plutonium (IV) complexes of the f-element extractant 2,5-Bis(diphenylphosphinomethyl)benzene P,P'-dioxide including structural characterization of a plutonium (IV) alkoxide

    Energy Technology Data Exchange (ETDEWEB)

    Matonic, John H.; Enriquez, Alejandro E.; Scott, Brian L.; Neu, Mary P. [Los Alamos National Laboratory, Chemistry and Nuclear Materials and Technology Divisions, Los Alamos, New Mexico (United States); Paine, Robert T. [University of New Mexico, Department of Chemistry, Albuquerque, New Mexico (United States)

    2002-11-01

    The bidentate ligand 2,6-bis[(diphenylphosphino)-methyl]benzene P,P'-dioxide (POPO) is a liquid-liquid extraction agent for the separation of actinide and lanthanide ions in acid. When combined with an aqueous nitric acid solution of Pu(IV), POPO produces 1:1 coordination complexes Pu(POPO)(NO{sub 3}){sub 2}Cl{sub 2} (3) Pu(POPO)(NO{sub 3}){sub 3}(OMe) (4). The former was isolated from a chloroform solution and the latter from a basic methanol solution. Monoclinic crystals of both complexes were characterized by single-crystal, X-ray diffraction analysis. Compound 3 is eight-coordinate, containing a bidentate POPO ligand, two bidentate nitrates, and two chloride. Complex 4 is nine-coordinate and contains a bidentate POPO ligand, three bidentate nitrates, and one methoxide. The plutonium to oxygen distances, Pu-O(P), of the bound phosphine oxide moieties are 2.250(3) A and 2.238(3) A in complex 3, and 2.301(2) and 2.276(2) A in complex 4. Plutonium to nitrate distances, Pu-O(NO{sub 3}), range from 2.447(4) A to 2.468(4) A in 3 and from 2.456(3) to 2.544(3) A in 4. The plutonium to chloride, Pu-Cl, distances in 3 are 2.600(3) and 2.572(2) A. Nine-coordinate complex 4 has a short 2.027(3) A plutonium to methoxide oxygen distance and is the first structurally characterized plutonium alkoxide containing complex. (author)

  9. The xenograft antigen bound to Griffonia simplicifolia lectin 1-B(4). X-ray crystal structure of the complex and molecular dynamics characterization of the binding site.

    Science.gov (United States)

    Tempel, Wolfram; Tschampel, Sarah; Woods, Robert J

    2002-02-22

    The shortage of organs for transplantation into human patients continues to be a driving force behind research into the use of tissues from non-human donors, particularly pig. The primary barrier to such xenotransplantation is the reaction between natural antibodies present in humans and Old World monkeys and the Gal alpha(1-3)Gal epitope (xenograft antigen, xenoantigen) found on the cell surfaces of the donor organ. This hyperacute immune response leads ultimately to graft rejection. Because of its high specificity for the xenograft antigen, isolectin 1-B(4) from Griffonia simplicifolia (GS-1-B(4)) has been used as an immunodiagnostic reagent. Furthermore, haptens that inhibit natural antibodies also inhibit GS-1-B(4) from binding to the xenoantigen. Here we report the first x-ray crystal structure of the xenograft antigen bound to a protein (GS-1-B(4)). The three-dimensional structure was determined from orthorhombic crystals at a resolution of 2.3 A. To probe the influence of binding on ligand properties, we report also the results of molecular dynamics (MD) simulations on this complex as well as on the free ligand. The MD simulations were performed with the AMBER force-field for proteins augmented with the GLYCAM parameters for glycosides and glycoproteins. The simulations were performed for up to 10 ns in the presence of explicit solvent. Through comparison with MD simulations performed for the free ligand, it has been determined that GS-1-B(4) recognizes the lowest energy conformation of the disaccharide. In addition, the x-ray and modeling data provide clear explanations for the reported specificities of the GS-1-B(4) lectin. It is anticipated that a further understanding of the interactions involving the xenograft antigen will help in the development of therapeutic agents for application in the prevention of hyperacute xenograft rejection.

  10. New Mn(II, Ni(II, Cd(II, Pb(II complexes with 2-methylbenzimidazole and other ligands. Synthesis, spectroscopic characterization, crystal structure, magnetic susceptibility and biological activity studies

    Directory of Open Access Journals (Sweden)

    Shayma A. Shaker

    2016-11-01

    Full Text Available Synthesis and characterization of Mn(II, Ni(II, Cd(II and Pb(II mixed ligand complexes of 2-methylbenzimidazole with other ligands have been reported. The structure of the ligands and their complexes was investigated using elemental analysis, IR, UV–Vis, (1H, 13C NMR spectroscopy, molar conductivity and magnetic susceptibility measurements. In all the studies of complexes, the 2-methylbenzimidazole behaves as a neutral monodentate ligand which is coordinated with the metal ions through the N atom. While benzotriazole behaves as a neutral bidentate ligand which is coordinated with the Ni(II ion through the two N atoms. Moreover, the N-acetylglycine behaves as a bidentate ligand which is coordinated with the Mn(II, Ni(II and Pb(II ions through the N atom and the terminal carboxyl oxygen atom. The magnetic and spectral data indicate the tetrahedral geometry for Mn(II complex, irregular tetrahedral geometry for Pb(II complex and octahedral geometry for Ni(II complex. The X-ray single crystal diffraction method was used to confirm a centrosymmetric dinuclear Cd(II complex as each two metal ions are linked by a pair of thiocyanate N = S bridge. Two 2-methylbenzimidazole N-atom donors and one terminal thiocyanate N atom complete a highly distorted square pyramid geometry around the Cd atom. Besides, different cell types were used to determine the inhibitory effect of Mn(II, Ni(II, Cd(II and Pb(II complexes on cell growth using MTT assay. Cd(II complex showed cytotoxic effect on various types of cancer cell lines with different EC50 values.

  11. Complex Analyses of Plankton Structure and Function

    Directory of Open Access Journals (Sweden)

    Karl E. Havens

    2001-01-01

    Full Text Available This paper critically evaluates some complex methods that have been used to characterize the structure and function of freshwater plankton communities. The focus is on methods related to plankton size structure and carbon transfer. The specific methods reviewed are 1 size spectrum analysis, 2 size-fractionated phytoplankton productivity, 3 size-fractionated zooplankton grazing, 4 plankton ecological transfer efficiency, and 5 grazer effects on phytoplankton community structure. Taken together, these methods can provide information on community ecological properties that are directly related to practical issues including water quality and fisheries productivity. However, caution is warranted since application without a complete understanding of assumptions and context of the manipulations could lead to erroneous conclusions. As an example, experimental studies involving the addition or removal of zooplankton, especially when coupled with nutrient addition treatments, could provide information on the degree of consumer vs. resource control of phytoplankton. Resource managers subsequently could use this information in developing effective measures for controlling nuisance algal biomass. However, the experiments must be done critically and with sufficient safeguards and other measurements to ensure that treatments (e.g., zooplankton exclosure by screening of water actually are successful and do not introduce other changes in the community (e.g., removal of large algae. In all of the methods described here, the investigator must take care when generalizing results and, in particular, carry out a sufficient number of replications to encompass both the major seasonal and spatial variation that occurs in the ecosystem.

  12. Alpha complexes in protein structure prediction

    DEFF Research Database (Denmark)

    Winter, Pawel; Fonseca, Rasmus

    2015-01-01

    Reducing the computational effort and increasing the accuracy of potential energy functions is of utmost importance in modeling biological systems, for instance in protein structure prediction, docking or design. Evaluating interactions between nonbonded atoms is the bottleneck of such computations......-complexes and kinetic a-complexes in protein related problems (e.g., protein structure prediction and protein-ligand docking) deserves furhter investigation.)......-complexes from scratch for every configuration encountered during the search for the native structure would make this approach hopelessly slow. However, it is argued that kinetic a-complexes can be used to reduce the computational effort of determining the potential energy when "moving" from one configuration...

  13. Predicting complex mineral structures using genetic algorithms.

    Science.gov (United States)

    Mohn, Chris E; Kob, Walter

    2015-10-28

    We show that symmetry-adapted genetic algorithms are capable of finding the ground state of a range of complex crystalline phases including layered- and incommensurate super-structures. This opens the way for the atomistic prediction of complex crystal structures of functional materials and mineral phases.

  14. Clonal Structure and Characterization of Staphylococcus aureus Strains from Invasive Infections in Paediatric Patients from South Poland: Association between Age, spa Types, Clonal Complexes, and Genetic Markers.

    Science.gov (United States)

    Ilczyszyn, Weronika M; Sabat, Artur J; Akkerboom, Viktoria; Szkarlat, Anna; Klepacka, Joanna; Sowa-Sierant, Iwona; Wasik, Barbara; Kosecka-Strojek, Maja; Buda, Aneta; Miedzobrodzki, Jacek; Friedrich, Alexander W

    2016-01-01

    The aim of current study was to examine clonal structure and genetic profile of invasive Staphylococcus aureus isolates recovered from infants and children treated at the Jagiellonian University Children's Hospital of Krakow, Poland. The 107 invasive S. aureus isolates, collected between February 2012 and August 2014, were analysed retrospectively. Antimicrobial susceptibility testing, spa typing and DNA microarray analysis were performed to determine clonal distribution, diversity and gene content in regard to patients characteristics. In total, 107 isolates were recovered from 88 patients with clinical symptoms of invasive bacterial infection. The final set of 92 non-duplicate samples included 38 MRSA isolates. Additionally, a set of 54 S. aureus isolates collected during epidemiological screening was genotyped and analysed. There were 72 healthcare-associated (HCA) and 20 community-onset (CO) infection events caused by 33 and 5 MRSA isolates, respectively. The majority of isolates were affiliated with the major European clonal complexes CC5 (t003, spa-CC 002), CC45 (spa-CC 015), CC7 or CC15 (t084, t091, spa-CC 084). Two epidemic clones (CC5-MRSA-II or CC45-MRSA-IV) dominated among MRSA isolates, while MSSA population contained 15 different CCs. The epidemiological screening isolates belonged to similar genetic lineages as those collected from invasive infection cases. The HCA infection events, spa types t003, t2642 or CC5 were significantly associated with infections occurring in neonates and children under 5 years of age. Moreover, carriage of several genetic markers, including erm(A), sea (N315), egc-cluster, chp was significantly higher in isolates obtained from children in this age group. The spa types t091 and t008 were underrepresented among patients aged 5 years or younger, whereas spa type t008, CC8 and presence of splE was associated with infection in children aged 10 years or older. The HCA-MRSA strains were most frequently found in children under 5

  15. Synthesis, structural characterization, antibacterial activity and computational studies of new cobalt (II) complexes with 1,1,3,3-tetrakis (3,5-dimethyl-1-pyrazolyl)propane ligand

    Science.gov (United States)

    Beheshti, Azizolla; Safaeiyan, Forough; Hashemi, Faeze; Motamedi, Hossein; Mayer, Peter; Bruno, Giuseppe; Rudbari, Hadi Amiri

    2016-11-01

    Two new mono- and dinuclear Co(II) complexes namely [Co(tdmpp)Cl2]2·H2O (1) and [Co2(tdmpp)Cl4] (2) (where tdmpp = 1,1,3,3-tetrakis(3,5-dimethyl-1-pyrazolyl)propane) were prepared by one-pot reactions in methanol as a solvent. These compounds have been characterized by single crystal X-ray diffraction, elemental analysis, infrared spectroscopy, antibacterial activity and computational studies. In both complexes, Co (II) atom is tetrahedrally coordinated by two N atoms from one of the chelating bidentate bis(3,5-dimethylpyrazolyl)methane units of the tdmpp ligand and two Cl as terminal ligands. In these structures, the neighboring [Co(tdmpp)Cl2]2·H2O (1) and [Co2(tdmpp)Cl4] (2) molecules are joined together by the intermolecular Csbnd H⋯Cl hydrogen bonds to form a 1D chain structure. As a consequence of the intermolecular Csbnd H⋯π interactions these chains are further linked to generate a two-dimensional non-covalent bonded structure. The in vitro antibacterial activity studies of the free tdmpp ligand, compounds 1 and 2 show that the ability of these compounds to inhibit growth of the tested bacteria increase progressively from tdmpp to the dinuclear complex 2. Molecular-docking investigations between the five standard antibiotic, free tdmpp ligand, title complexes and five biological macromolecule enzymes (receptors) were carried out from using Autodock vina function. The results of docking studies confirmed that the metal complexes are more active than the free ligand. This is consistent with the results obtained by the antibacterial activities of these compounds.

  16. Synthesis and structural characterization of some compounds involving metal-metal bonding of tellurium, bismuth, and zirconium. [Complex with hexaoxadiazabicyclohexacosane potassium

    Energy Technology Data Exchange (ETDEWEB)

    Cisar, A.

    1978-08-01

    Salts of the tritelluride(2-) and tetrabismuthide(2-) ions with the complex cation (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo(8.8.8)hexacosane potassium) (abbreviated crypt K/sup +/) were synthesized and their structures determined. The dark red (crypt K/sup +/)/sub 2/ Te/sub 3//sup 2 -/.en was produced by oxidation of K/sub 2/Te with an excess of tellurium and the very dark green (crypt K/sup +/)/sub 2/Bi/sub 4//sup 2 -/ was produced by the reaction of either K/sub 3/Bi, K/sub 3/Bi/sub 2/, K/sub 5/Bi/sub 4/, or KBi/sub 2/ with solvent. (Crypt K/sup +/)/sub 2/Te/sub 3//sup 2 -/.en crystallizes in the trigonal space group P3/sub 2/ with a = 12.229(1)A and c = 31.242(4)A and three formula units per cell. The Te/sub 3//sup 2 -/ ion has bond lengths of 2.692(5) and 2.720(4)A, an angle of 113.1(2)/sup 0/, and a hydrogen bond to an en molecule with d/sub Te-N/ = 3.46(6)A. (Crypt K/sup +/)/sub 2/Bi/sub 4//sup 2 -/ crystallizes in the triclinic space group P anti 1 with a = 11.604(4)A, b = 11.796(4)A, c = 11.096(3)A, ..cap alpha.. = 98.12(3)/sup 0/, ..beta.. = 98.02(3)/sup 0/, and ..gamma.. = 61.37(3)/sup 0/ and one formula per cell. The structure of the more common form of stoichiometric ZrCl/sub 2/, which is isostructural with 3R-MoS/sub 2/, (R3m, with a = 3.3819(3) and c = 19.378(3)A) was refined from single crystal data. A cluster form which is isostructural with Zr/sub 6/I/sub 12/ was found and its structure determined from powder data. 6T-Zr/sub 1+x/Cl/sub 2/ was determined from an intergrown ''single'' crystal containing 3R-ZrCl/sub 2/, to be a 6-slab superstructure based on a 2H/sub b/-MoS/sub 2/ type subcell with a = 3.3791(4) and c = 38.713(7)A. Another, 18T-Zr/sub 1+y/Cl/sub 2/, found in both single crystals and powder, has an 18 slab repeat sequence with a = 3.3820(2) and c = 116.21(2)A. The third is of unknown composition and exhibits ordering along a.

  17. A new Salen-type azo-azomethine ligand and its Ni(II), Cu(II) and Zn(II) complexes: Synthesis, spectral characterization, crystal structure and photoluminescence studies.

    Science.gov (United States)

    Ozkan, Gozde; Kose, Muhammet; Zengin, Huseyin; McKee, Vickie; Kurtoglu, Mukerrem

    2015-11-05

    A novel Salen-type azo-azomethine ligand H2agen, 2,2'-{ethane-1,2-diylbis[nitrilomethylylidene]}bis{4-[ethylphenyldiazenyl]phenol}, formed by the 1:2M condensation of ethane-1,2-diamine with 5-[(4-ethylphenyl)diazenyl]-2-hydroxybenzaldehyde and its nickel(II), copper(II), and zinc(II) complexes were synthesized and characterized by the spectroscopic and analytical methods. The UV-vis spectra of the ligand were investigated in three organic solvents (DMSO, DMF and CHCl3). The ligand shows two absorption bands assigned to π-π(∗) and n-π(∗) transitions in the solvents used. Cu(II), and Ni(II) are tetra-coordinate binding to two phenolic oxygens and two imine nitrogens in approximate square planar geometry. Zn(II) also coordinates using the same sites like other metals but gave tetragonal configuration. Molecular structure of the Cu(II) complex [Cu(agen)] was determined by single crystal X-ray diffraction study. The X-ray data revealed that crystallographic imposed symmetry was absent for the complex molecule. In the structure, the Cu(II) ion is coordinated to two phenolate oxygen atoms and two imine nitrogen atoms of the azo-azomethine ligand with approximate square planar geometry. The ligand H2agen and its metal complexes exhibit strong blue emissions with irradiation. Fluorescence quantum yields and excited-state lifetimes for the ligand and its complexes were obtained. The H2agen ligand had a 35% quantum yield and a 3.27 ns excited-state lifetime. Complexation with metal ions caused reductions in intensities and quantum yields. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. The structure of complex Lie groups

    CERN Document Server

    Lee, Dong Hoon

    2001-01-01

    Complex Lie groups have often been used as auxiliaries in the study of real Lie groups in areas such as differential geometry and representation theory. To date, however, no book has fully explored and developed their structural aspects.The Structure of Complex Lie Groups addresses this need. Self-contained, it begins with general concepts introduced via an almost complex structure on a real Lie group. It then moves to the theory of representative functions of Lie groups- used as a primary tool in subsequent chapters-and discusses the extension problem of representations that is essential for studying the structure of complex Lie groups. This is followed by a discourse on complex analytic groups that carry the structure of affine algebraic groups compatible with their analytic group structure. The author then uses the results of his earlier discussions to determine the observability of subgroups of complex Lie groups.The differences between complex algebraic groups and complex Lie groups are sometimes subtle ...

  19. Coherent information structure in complex computation.

    Science.gov (United States)

    Lizier, Joseph T; Prokopenko, Mikhail; Zomaya, Albert Y

    2012-09-01

    We have recently presented a framework for the information dynamics of distributed computation that locally identifies the component operations of information storage, transfer, and modification. We have observed that while these component operations exist to some extent in all types of computation, complex computation is distinguished in having coherent structure in its local information dynamics profiles. In this article, we conjecture that coherent information structure is a defining feature of complex computation, particularly in biological systems or artificially evolved computation that solves human-understandable tasks. We present a methodology for studying coherent information structure, consisting of state-space diagrams of the local information dynamics and a measure of structure in these diagrams. The methodology identifies both clear and "hidden" coherent structure in complex computation, most notably reconciling conflicting interpretations of the complexity of the Elementary Cellular Automata rule 22.

  20. Structural and chelation behaviors of new Ru(II), Pt(IV) and Ir(III) gatifloxacin drug complexes: Spectroscopic characterizations

    Science.gov (United States)

    Alghamdi, Mohammed T.; Alsibaai, A. A.; El-Shahawi, M. S.; Refat, Moamen S.

    2017-02-01

    The interaction between gatifloxacin drug (GAT) with some transition metals (Ru(III), Pt(IV) and Ir(III)) yield the complexes of formulas [Ru(GAT-NH4)(Cl)3(H2O)2], [Pt(GAT-NH4)2(Cl)4]·3H2O and [Ir(GAT-NH4)2(Cl)2(H2O)2]·Cl·2H2O at pH = 7-8. The composition of the GAT complexes was confirmed by elemental data. The IR frequencies reveal the coordination of the GAT with metal ions and the coordination mode of the sbnd N atom of 3-methylpiperazinyl moiety to metal. XRD pattern show isomorphism among the complexes with similar chelation behavior. Scanning electron microscope (SEM) and transmission electron microscopy (TEM) were used to identify the particle size of GAT complexes. The thermal data reveals that various steps of decomposition of the complexes to form their metal oxide as final product. The electronic spectra and the magnetic susceptibility values reveal that the coordination and geometry of Ru3+, Pt4+ and Ir3+ complexes possess distorted octahedral geometry with six number of coordination. Thermodynamic parameters (E*, ΔS*, ΔH* and ΔG*) were calculated from TG curves dependent on Coats-Redfern and Horowitz-Metzeger non-isothermal methods.

  1. Structural entanglements in protein complexes

    Science.gov (United States)

    Zhao, Yani; Chwastyk, Mateusz; Cieplak, Marek

    2017-06-01

    We consider multi-chain protein native structures and propose a criterion that determines whether two chains in the system are entangled or not. The criterion is based on the behavior observed by pulling at both termini of each chain simultaneously in the two chains. We have identified about 900 entangled systems in the Protein Data Bank and provided a more detailed analysis for several of them. We argue that entanglement enhances the thermodynamic stability of the system but it may have other functions: burying the hydrophobic residues at the interface and increasing the DNA or RNA binding area. We also study the folding and stretching properties of the knotted dimeric proteins MJ0366, YibK, and bacteriophytochrome. These proteins have been studied theoretically in their monomeric versions so far. The dimers are seen to separate on stretching through the tensile mechanism and the characteristic unraveling force depends on the pulling direction.

  2. Topological complexity of crystal structures: quantitative approach.

    Science.gov (United States)

    Krivovichev, Sergey

    2012-05-01

    The topological complexity of a crystal structure can be quantitatively evaluated using complexity measures of its quotient graph, which is defined as a projection of a periodic network of atoms and bonds onto a finite graph. The Shannon information-based measures of complexity such as topological information content, I(G), and information content of the vertex-degree distribution of a quotient graph, I(vd), are shown to be efficient for comparison of the topological complexity of polymorphs and chemically related structures. The I(G) measure is sensitive to the symmetry of the structure, whereas the I(vd) measure better describes the complexity of the bonding network. © 2012 International Union of Crystallography

  3. Synthesis and crystal structure of trinuclear potassium(I) complex ...

    African Journals Online (AJOL)

    A furazan-based trinuclear potassium(I) complex derived from the oxy-bridged bis(gem-dinitro)furazan (OBNF) and triaminoguanidinium (TGA) units was synthesized and characterized by elemental analyses, nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. The single crystal X-ray structure of the ...

  4. Characterizing the molecular architectures of chromatin-modifying complexes.

    Science.gov (United States)

    Setiaputra, Dheva T; Yip, Calvin K

    2017-11-01

    Eukaryotic cells package their genome in the form of a DNA-protein complex known as chromatin. This organization not only condenses the genome to fit within the confines of the nucleus, but also provides a platform for a cell to regulate accessibility to different gene sequences. The basic packaging element of chromatin is the nucleosome, which consists of 146 base pairs of DNA wrapped around histone proteins. One major means that a cell regulates chromatin structure is by depositing post-translational modifications on nucleosomal histone proteins, and thereby altering internucleosomal interactions and/or binding to different chromatin associated factors. These chromatin modifications are often catalyzed by multi-subunit enzyme complexes, whose large size, sophisticated composition, and inherent conformational flexibility pose significant technical challenges to their biochemical and structural characterization. Multiple structural approaches including nuclear magnetic resonance spectroscopy, X-ray crystallography, single-particle electron microscopy, and crosslinking coupled to mass spectrometry are often used synergistically to probe the overall architecture, subunit organization, and catalytic mechanisms of these macromolecular assemblies. In this review, we highlight several recent chromatin-modifying complexes studies that embodies this multipronged structural approach, and explore common themes amongst them. This article is part of a Special Issue entitled: Biophysics in Canada, edited by Lewis Kay, John Baenziger, Albert Berghuis and Peter Tieleman. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Synthesis, Characterization, X-ray Structure and Biological Screenings of Silver(I) and Copper(I) Complexes of Triphenylphosphine Dithiocarboxylate

    NARCIS (Netherlands)

    Abbas, Syed Mustansar; Sirajuddin, Muhammad; Ali, Saqib; Hussain, Syed Tajammul; Shah, Farooq Ali; Meetsma, Auke

    Two new transition metal dithiocarboxylates with general formula R2ML, where R = P(C6H5)(3), M=Ag(I) (1), Cu(I) (2) and L = Sodium salt of 4-formylpiperazine-1-carbodithioate, have been synthesized and characterized by elemental analysis, FT-IR, multinuclear NMR (H-1, C-13 and P-31) and mass

  6. New platinum (II) and palladium (II) complexes of coumarin-thiazole Schiff base with a fluorescent chemosensor properties: Synthesis, spectroscopic characterization, X-ray structure determination, in vitro anticancer activity on various human carcinoma cell lines and computational studies.

    Science.gov (United States)

    Şahin, Ömer; Özdemir, Ümmühan Özmen; Seferoğlu, Nurgül; Genc, Zuhal Karagöz; Kaya, Kerem; Aydıner, Burcu; Tekin, Suat; Seferoğlu, Zeynel

    2018-01-01

    A new coumarin-thiazole based Schiff base (Ligand, L) and its Pd(II), Pt(II) complexes; ([Pd(L) 2 ] and [Pt(L) 2 ]), were synthesized and characterized using spectrophotometric techniques (NMR, IR, UV-vis, LC-MS), magnetic moment, and conductivity measurements. A single crystal X-ray analysis for only L was done. The crystals of L have monoclinic crystal system and P21/c space group. To gain insight into the structure of L and its complexes, we used density functional theory (DFT) method to optimize the molecules. The photophysical properties changes were observed after deprotonation of L with CN - via intermolecular charge transfer (ICT). Additionally, as the sensor is a colorimetric and fluorimetric cyanide probe containing active sites such as coumarin-thiazole and imine (CH=N), it showed fast color change from yellow to deep red in the visible region, and yellow fluorescence after CN - addition to the imine bond, in DMSO. The reaction mechanisms of L with CN - , F - and AcO - ions were evaluated using 1 H NMR shifts. The results showed that, the reaction of L with CN - ion was due to the deprotonation and addition mechanisms at the same time. The anti-cancer activity of L and its Pd(II) and Pt(II) complexes were evaluated in vitro using MTT assay on the human cancer lines MCF-7 (human breast adenocarcinoma), LS174T (human colon carcinoma), and LNCAP (human prostate adenocarcinoma). The anti-cancer effects of L and its complexes, on human cells, were determined by comparing the half maximal inhibitory concentration (IC 50 ) values. The activity results showed that, the Pd(II) complex of L has higher anti-tumor effect than L and its Pt(II) complex against the tested human breast adenocarcinoma (MCF-7), human prostate adenocarcinoma (LNCAP), and human colon carcinoma (LS174T) cell lines. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Pyrazine-based organometallic complex: synthesis, characterization, and supramolecular chemistry.

    Science.gov (United States)

    Bhowmick, Sourav; Chakraborty, Sourav; Das, Atanu; Rajamohanan, P R; Das, Neeladri

    2015-03-16

    The design, synthesis, and characterization of a new pyrazine-based ditopic platinum(II) organometallic complex are reported. The molecular structure of the organoplatinum pyrazine dipod was determined by single-crystal X-ray crystallography. The potential utility of this organometallic ditopic acceptor as a building block in the construction of neutral metallasupramolecular macrocycles containing the pyrazine motif was explored. Pyrazine motifs containing supramolecules were characterized by multinuclear NMR (including (1)H DOSY), mass spectrometry, and elemental analysis. The geometry of each supramolecular framework was optimized by employing the PM6 semiempirical molecular orbital method to predict its shape and size. The ability of the pyrazine-based organoplatinum complex to act as a host for nitroaromatic guest (2,4-dinitrotoluene and PA) molecules was explored by isothermal titration calorimetry (ITC). The binding stoichiometry and thermodynamic parameters of these host-guest complexation reactions were evaluated using ITC. Theoretical calculations were performed to obtain insight into the binding pattern between the organometallic host and nitroaromatic guests. The preferable binding propensity of the binding sites of complex 1 for both nitroaromatics (PA and 2,4-dinitrotoluene) determined by molecular simulation studies corroborates well with the experimental results as obtained by ITC experiments.

  8. Instrumentation for the Characterization of Inflatable Structures

    Science.gov (United States)

    Swanson, Gregory T.; Cassell, Alan M.; Johnson, R. Keith

    2012-01-01

    Current entry, descent, and landing technologies are not practical for heavy payloads due to mass and volume constraints dictated by limitations imposed by launch vehicle fairings. Therefore, new technologies are now being explored to provide a mass- and volume-efficient solution for heavy payload capabilities, including Inflatable Aerodynamic Decelerators (IAD) [1]. Consideration of IADs for space applications has prompted the development of instrumentation systems for integration with flexible structures to characterize system response to flight-like environment testing. This development opportunity faces many challenges specific to inflatable structures in extreme environments, including but not limited to physical flexibility, packaging, temperature, structural integration and data acquisition [2]. In the spring of 2012, two large scale Hypersonic Inflatable Aerodynamic Decelerators (HIAD) will be tested in the National Full-Scale Aerodynamics Complex s 40 by 80 wind tunnel at NASA Ames Research Center. The test series will characterize the performance of a 3.0 m and 6.0 m HIAD at various angles of attack and levels of inflation during flight-like loading. To analyze the performance of these inflatable test articles as they undergo aerodynamic loading, many instrumentation systems have been researched and developed. These systems will utilize new experimental sensing systems developed by the HIAD ground test campaign instrumentation team, in addition to traditional wind tunnel sensing techniques in an effort to improve test article characterization and model validation. During the 2012 test series the instrumentation systems will target inflatable aeroshell static and dynamic deformation, structural strap loading, surface pressure distribution, localized skin deflection, and torus inflation pressure. This paper will offer an overview of inflatable structure instrumentation, and provide detail into the design and implementation of the sensors systems that will

  9. Structure and dynamics of GPCR signaling complexes.

    Science.gov (United States)

    Hilger, Daniel; Masureel, Matthieu; Kobilka, Brian K

    2018-01-01

    G-protein-coupled receptors (GPCRs) relay numerous extracellular signals by triggering intracellular signaling through coupling with G proteins and arrestins. Recent breakthroughs in the structural determination of GPCRs and GPCR-transducer complexes represent important steps toward deciphering GPCR signal transduction at a molecular level. A full understanding of the molecular basis of GPCR-mediated signaling requires elucidation of the dynamics of receptors and their transducer complexes as well as their energy landscapes and conformational transition rates. Here, we summarize current insights into the structural plasticity of GPCR-G-protein and GPCR-arrestin complexes that underlies the regulation of the receptor's intracellular signaling profile.

  10. Electronic Structure of Metallacyclophosphazene and Metallacyclothiazene Complexes.

    Science.gov (United States)

    Sundermann, Andreas; Schoeller, Wolfgang W.

    1999-12-27

    The electronic structure of metallacyclotriphosphazene complexes with several substituents at the phosphorus atoms and metallacyclothiazene complexes is explored for a variety of transition metal elements using density functional theory methods. Accordingly the metallacyclophosphazenes possess a large HOMO-LUMO energy separation while the metallacyclothiazenes bear stronger open-shell character. In addition our calculations predict the existence of experimentally so far unknown dimetallacyclophosphazenes. All structures show to be highly dynamical. The double bond character of the transition metal nitrogen bond is much less pronounced than in nitrido or imido complexes. For the ring compounds vibrational spectra are reported and compared with experimental data.

  11. Structural Characterization of supramolecule/nanoparticle nanocomposites

    Science.gov (United States)

    Xiao, Yihan; Xu, Ting

    Supramolecular nanocomposites offer great opportunities toward functional materials. However, these systems also challenge our basic understanding in self-assembly in multiple component systems. The multicomponent nature of the supramolecular system introduces significant complexity in mapping out the hierarchical spatial distribution of each building block. To this end, various techniques have been adopted to decouple the convoluted structures. Transmission electron microscopy (TEM), scanning transmission electron microscopy tomography (STEMT) and small-angle X-ray scattering (SAXS) collaboratively determined the hexagonal structure of nanoparticle superlattice. Resonant X-ray scattering (RSoXS) provides a novel opportunity to selectively characterize the lamellar arrangement of supramolecular matrix. Finally, a model is proposed for the nanocomposite morphology based on these results that is critical toward delineation of energetic contribution from individual component. The work was supported by the U.S. Department of Energy, Office of Science, Materials Sciences and Engineering Division.

  12. Synthesis and characterization of transition metal complexes ...

    African Journals Online (AJOL)

    Ni(II) complex of HMPFCH has been assigned a dimeric square planar geometry. Cu(II) complex of HMPFCH has been proposed an octahedral geometry. The ligands and their metal chelates were screened against S. aureus and P. aeruginosa. The ligands and the metal complexes have been found to be active against ...

  13. Modelling the structure of complex networks

    DEFF Research Database (Denmark)

    Herlau, Tue

    networks has been independently studied as mathematical objects in their own right. As such, there has been both an increased demand for statistical methods for complex networks as well as a quickly growing mathematical literature on the subject. In this dissertation we explore aspects of modelling complex......A complex network is a systems in which a discrete set of units interact in a quantifiable manner. Representing systems as complex networks have become increasingly popular in a variety of scientific fields including biology, social sciences and economics. Parallel to this development complex....... The next chapters will treat some of the various symmetries, representer theorems and probabilistic structures often deployed in the modelling complex networks, the construction of sampling methods and various network models. The introductory chapters will serve to provide context for the included written...

  14. Synthesis of Hetero- and Homo-multinuclear Complexes with a Tetracyanonickelate Anion: Structural Characterization [Cu(bcen)Ni(CN)4]2.

    Science.gov (United States)

    Vafazadeh, Rasoul; Dehghani-Firouzabadi, Amin; Willis, C Anthony

    2017-09-01

    Two new complexes [Cu(bcen)Ni(CN)4]2 (1) and [Ni(bcen)Ni(CN)4] (2) where bcen is 4,7-diazadecanediamide, were synthesized by reaction of equimolar amounts of M(NO3)2 (M = Cu and Ni), bcen ligand and K2[Ni(CN)4]. Single-crystal X-ray diffraction analysis of compound 1, shows that the bcen ligand acts as a tridentate chelate, coordinating to the Cu(II) ion via the two nitrogen atoms of the amine groups and one oxygen atom of one amide group, and the other amide unit is left uncoordinated. The coordination geometry around the Cu(II) ions is five coordinate with a distorted square pyramid geometry, comprising two nitrogen atoms and one oxygen atom belonging to the bcen ligand and two nitrogen atoms of the cyano groups of two Ni(CN)4 2- units. The distance between the copper ion and the amide oxygen of the dangling arm of an adjacent tetranuclear species is within the expected range for an axial Cu-O bond, and hence suggests that the amide oxygen of an adjacent tetranuclear complex may weakly coordinate to the copper ion in an axial position. These contacts link the tetranuclear species into infinite chain polymers.

  15. Structural Features of Caspase-Activating Complexes

    Directory of Open Access Journals (Sweden)

    Hyun Ho Park

    2012-04-01

    Full Text Available Apoptosis, also called programmed cell death, is an orderly cellular suicide program that is critical for the development, immune regulation and homeostasis of a multi-cellular organism. Failure to control this process can lead to serious human diseases, including many types of cancer, neurodegenerative diseases, and autoimmununity. The process of apoptosis is mediated by the sequential activation of caspases, which are cysteine proteases. Initiator caspases, such as caspase-2, -8, -9, and -10, are activated by formation of caspase-activating complexes, which function as a platform to recruit caspases, providing proximity for self-activation. Well-known initiator caspase-activating complexes include (1 DISC (Death Inducing Signaling Complex, which activates caspases-8 and 10; (2 Apoptosome, which activates caspase-9; and (3 PIDDosome, which activates caspase-2. Because of the fundamental biological importance of capases, many structural and biochemical studies to understand the molecular basis of assembly mechanism of caspase-activating complexes have been performed. In this review, we summarize previous studies that have examined the structural and biochemical features of caspase-activating complexes. By analyzing the structural basis for the assembly mechanism of the caspase-activating complex, we hope to provide a comprehensive understanding of caspase activation by these important oligomeric complexes.

  16. Synthesis and Structural Characterization of a New Tetranuclear Nickel(II Sulfato Complex Containing the Anionic Form of Di-2-Pyridyl Ketone Oxime

    Directory of Open Access Journals (Sweden)

    Eleni Moushi

    2011-01-01

    Full Text Available The preparation and crystal structure of a tetranuclear Ni(II sulfato cluster containing the anion of di-2-pyridyl ketone oxime, (py2CNO−, are reported. Treatment of NiSO4·6H2O with one equivalent of (py2CNOH and one equivalent of NEt3 in MeOH leads to the compound [Ni4{(py2CNO}4(SO42(MeOH4] (1 in moderate yield. The metal ions are linked together by two 3.2111 and two 2.1110 (Harris notation (py2CNO− ligands, as well as two 2.1100 SO42− ions to create a rare metallacrown-type (12-MC-4 ring. Strong H-bond intermolecular interactions in 1 lead to the formation of a 1D chain along the axis. Characteristic IR bands are discussed in terms of the known structure of 1.

  17. Behavior of heptavalent technetium in concentrated triflic acid under alpha-irradiation. Technetium-triflate complex characterized by X-ray absorption fine structure spectroscopy and DFT

    Energy Technology Data Exchange (ETDEWEB)

    Denden, Ibtihel; Blain, Guillaume; Fattahi, Massoud [SUBATECH Laboratory, Nantes (France); Roques, Jerome [Paris Sud Univ., Orsay (France). IPN Orsay; Poineau, Frederic [Nevada Univ., Las Vegas, NV (United States). Dept. of Chemistry and Biochemistry; Solari, Pier Lorenzo [CEA, Gif-sur-Yvette (France). DEN/DPC/SEARS; Schlegel, Michel L. [Synchrotron SOLEIL, Gif-sur-Yvette (France)

    2017-04-01

    The nature of the Tc species produced after the alpha-irradiation of Tc(VII) in concentrated triflic acid has been investigated by X-ray absorption fine structure (XAFS) spectroscopy and first principles calculations. Experimental and theoretical results are consistent with the formation of Tc{sup (V)}O(F{sub 3}CSO{sub 3}){sub 2}(H{sub 2}O){sub 2}{sup +}.

  18. A new anti-MRSA antibiotic complex, WAP-8294A II. Structure characterization of minor components by ESI LCMS and MS/MS.

    Science.gov (United States)

    Kato, Azusa; Hirata, Haruhisa; Ohashi, Yoshitami; Fujii, Kiyonaga; Mori, Kenji; Harada, Ken-ichi

    2011-05-01

    The anti-MRSA antibiotic, WAP-8294A, was isolated from the fermentation broth of Lysobacter sp. The major component, WAP-8294A2, is composed of 1 mol of Gly, L-Leu, L-Glu, D-Asn, D-Trp, D-threo-β-hydroxyasparagine, N-Me-D-Phe and N-Me-L-Val, and 2 mol of L-Ser, D-Orn and D-3-hydroxy-7-Me-octanoic acid. The structure of the WAP-8294A2 was mainly determined as a cyclic depsipeptide by 2D NMR experiments. However, it was difficult to use the NMR experiment to determine the minor components, A1, A4 and Ax13, isolated in small amounts. In the present study, ESI MS/MS was applied to the structure elucidation of these minor components. The structures of these minor components were determined on the basis of the fragmentation pattern of the product ions of WAP-8294A2 in the ESI MS/MS. As a result, it was confirmed that A1 and A4 had the same amino acid sequence as A2, while A1 and A4 had the 3-OH-octanoic acid and 3-OH-8-Me-nonanoic acid, respectively, in the place of the 3-OH-7-Me-octanoic acid in A2. In the structure of Ax13, it was found that Gly of A2 was changed to β-Ala of Ax13. © 2011 Japan Antibiotics Research Association All rights reserved

  19. Characterization of the Deoxynucleotide Triphosphate Triphosphohydrolase (dNTPase) Activity of the EF1143 Protein from Enterococcus faecalis and Crystal Structure of the Activator-Substrate Complex

    Energy Technology Data Exchange (ETDEWEB)

    Vorontsov, Ivan I.; Minasov, George; Kiryukhina, Olga; Brunzelle, Joseph S.; Shuvalova, Ludmilla; Anderson, Wayne F. (NWU)

    2012-06-19

    The EF1143 protein from Enterococcus faecalis is a distant homolog of deoxynucleotide triphosphate triphosphohydrolases (dNTPases) from Escherichia coli and Thermus thermophilus. These dNTPases are important components in the regulation of the dNTP pool in bacteria. Biochemical assays of the EF1143 dNTPase activity demonstrated nonspecific hydrolysis of all canonical dNTPs in the presence of Mn{sup 2+}. In contrast, with Mg{sup 2+} hydrolysis required the presence of dGTP as an effector, activating the degradation of dATP and dCTP with dGTP also being consumed in the reaction with dATP. The crystal structure of EF1143 and dynamic light scattering measurements in solution revealed a tetrameric oligomer as the most probable biologically active unit. The tetramer contains four dGTP specific allosteric regulatory sites and four active sites. Examination of the active site with the dATP substrate suggests an in-line nucleophilic attack on the {alpha}-phosphate center as a possible mechanism of the hydrolysis and two highly conserved residues, His-129 and Glu-122, as an acid-base catalytic dyad. Structural differences between EF1143 apo and holo forms revealed mobility of the {alpha}3 helix that can regulate the size of the active site binding pocket and could be stabilized in the open conformation upon formation of the tetramer and dGTP effector binding.

  20. Structural insights into the exon junction complex.

    Science.gov (United States)

    Le Hir, Hervé; Andersen, Gregers Rom

    2008-02-01

    In higher eukaryotes, the exon junction complex is loaded onto spliced mRNAs at a precise position upstream of exon junctions, where it remains during nuclear export and cytoplasmic localisation until it is removed during the first translation round. The exon junction core complex consists of four proteins that form a dynamic binding platform for a variety of peripheral factors involved in mRNA metabolism. In the complex, mRNA binding is mediated by the DEAD-box protein eIF4AIII, and inhibition of its ATPase activity forms the mechanistic basis for the long-term stability of the complex. Recent crystal structures of the exon junction complex and eIF4AIII have provided the structural framework for investigating the function of the eIF4AIII ATPase and for localisation of surface patches involved in binding peripheral factors. Additionally, by comparison with the structure of a second DEAD-box protein also bound to RNA and ATP, general principles for the ATPase and unwinding/mRNP remodelling activities for this important group of enzymes can be proposed on the basis of atomic structures.

  1. Intraflagellar transport complex structure and cargo interactions.

    Science.gov (United States)

    Bhogaraju, Sagar; Engel, Benjamin D; Lorentzen, Esben

    2013-08-14

    Intraflagellar transport (IFT) is required for the assembly and maintenance of cilia, as well as the proper function of ciliary motility and signaling. IFT is powered by molecular motors that move along the axonemal microtubules, carrying large complexes of IFT proteins that travel together as so-called trains. IFT complexes likely function as adaptors that mediate interactions between anterograde/retrograde motors and ciliary cargoes, facilitating cargo transport between the base and tip of the cilium. Here, we provide an up-to-date review of IFT complex structure and architecture, and discuss how interactions with cargoes and motors may be achieved.

  2. Preparation and characterization of artemether inclusion complexes ...

    African Journals Online (AJOL)

    commercial brands, showing 3.9-, 1.8- and 1.6-fold increases, respectively, over a period of 15 min. Conclusion: Inclusion complexation of artemether ... of natural cyclodextrins – alpha (α), beta (β), and gamma (γ) with six, seven and eight ... 0.427 nm for alpha and gamma cyclodextrins respectively [2,3]. Inclusion complex ...

  3. MOLECULAR STRUCTURE AND MATERIALS CHARACTERIZATION

    Science.gov (United States)

    monocarboxylic acids and organosulfur compounds; solid state mass spectrometric studies; and the characterization of polyurethane elastomers with special reference to those used as binders for solid propellants.

  4. Robustness and structure of complex networks

    Science.gov (United States)

    Shao, Shuai

    This dissertation covers the two major parts of my PhD research on statistical physics and complex networks: i) modeling a new type of attack -- localized attack, and investigating robustness of complex networks under this type of attack; ii) discovering the clustering structure in complex networks and its influence on the robustness of coupled networks. Complex networks appear in every aspect of our daily life and are widely studied in Physics, Mathematics, Biology, and Computer Science. One important property of complex networks is their robustness under attacks, which depends crucially on the nature of attacks and the structure of the networks themselves. Previous studies have focused on two types of attack: random attack and targeted attack, which, however, are insufficient to describe many real-world damages. Here we propose a new type of attack -- localized attack, and study the robustness of complex networks under this type of attack, both analytically and via simulation. On the other hand, we also study the clustering structure in the network, and its influence on the robustness of a complex network system. In the first part, we propose a theoretical framework to study the robustness of complex networks under localized attack based on percolation theory and generating function method. We investigate the percolation properties, including the critical threshold of the phase transition pc and the size of the giant component Pinfinity. We compare localized attack with random attack and find that while random regular (RR) networks are more robust against localized attack, Erdoḧs-Renyi (ER) networks are equally robust under both types of attacks. As for scale-free (SF) networks, their robustness depends crucially on the degree exponent lambda. The simulation results show perfect agreement with theoretical predictions. We also test our model on two real-world networks: a peer-to-peer computer network and an airline network, and find that the real-world networks

  5. Exploring the Community Structure of Complex Networks

    OpenAIRE

    Drago, Carlo

    2016-01-01

    Regarding complex networks, one of the most relevant problems is to understand and to explore community structure. In particular it is important to define the network organization and the functions associated to the different network partitions. In this context, the idea is to consider some new approaches based on interval data in order to represent the different relevant network components as communities. The method is also useful to represent the network community structure, especially the ...

  6. Synthesis, characterization, and structure of a uranyl complex with a disulfide ligand, bis(di-n-propylammonium) disulfidobis(di-n-propylthiocarbamato)dioxouranate(VI)

    Energy Technology Data Exchange (ETDEWEB)

    Perry, Dale L. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials and Molecular Research Division; Zalkin, Allan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials and Molecular Research Division; Ruben, Helena [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Templeton, David H. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

    1982-01-01

    Olive green crystals of the title compound, [(n-C3H7)2NH2+]2[UO2((n-C3H7)2NCOS)2(S2)]2-, are orthorhombic, space group Pcan, with a = 15.326 (6) Å, b = 17.474 (6) Å, c = 14.728 (6) Å, and Z = 4 (dx = 1.45 g/cm3). For 1833 data, I > σ, R= 0.052, and Rw = 0.069. In this paper, the structure was revealed by single-crystal X-ray diffraction studies to consist of [(n-C3H7)2NH2]+ cations and [UO2((n-C3H7)2NCOS)2(S2)]2- anions with the uranium atom at the center of an irregular hexagonal bipyramid. The uranyl oxygen atoms occupy the axial positions. The equatorial coordination plane contains the disulfide (S22-) group bonded in a "side-on" fashion and two oxygen and two sulfur donor atoms from the mono-thiocarbamate ligands. Interatomic distances are S-S = 2.05 (1) Å and U-S = 2.711 (3) Å (disulfide), U-S = 2.873 (3) Å and U-O = 2.48 (1) Å (thiocarbamate), and U-O = 1.82 (1) Å (uranyl). Finally, the nitrogen atom in the dipropylammonium cation is hydrogen bonded to the uranyl oxygen atoms.

  7. Structural and Topology Optimization of Complex Civil Engineering Structures

    DEFF Research Database (Denmark)

    Hald, Frederik; Kirkegaard, Poul Henning; Andersen, Lars Vabbersgaard

    2013-01-01

    This paper shows the use of topology optimization for finding an optimized form for civil engineering structures. Today topology optimization and shape optimization have been integrated in several commercial finite element codes. Here, the topology of two complex civil engineering structures...

  8. Structures of some surfactant–polyelectrolyte complexes

    Indian Academy of Sciences (India)

    Abstract. Structures of complexes formed in aqueous solutions by some anionic polyelectrolytes. (double and single stranded (ds and ss) DNA, poly(vinyl sulfonate) (PVS), and poly(styrene sul- fonate) (PSS)) with a cationic surfactant system consisting of cetyltrimethylammonium bromide. (CTAB) and sodium ...

  9. Structure of simplicial complexes of graphs representing ...

    Indian Academy of Sciences (India)

    The multifractal analysis of the corresponding segments of the signal confirms that we deal with different types of stochastic processes. ... a multifractal structure, similar to that seen in many complex dynamical systems driven .... cess known as fractional Brownian motion, whereas the fluctuations in the initial segment of the ...

  10. Analysis of bacteriophage phi X174 gene A protein-mediated termination and reinitiation of phi X DNA synthesis. II. Structural characterization of the covalent phi X A protein-DNA complex.

    Science.gov (United States)

    Roth, M J; Brown, D R; Hurwitz, J

    1984-08-25

    In the preceeding paper (Brown, D. R., Roth, M. J., Reinberg, D., and Hurwitz, J. (1984) J. Biol. Chem. 259, 10545-10555), it was shown that following bacteriophage phi X174 (phi X) DNA synthesis in vitro using purified proteins, the phi X A protein could be detected covalently linked to nascent 32P-labeled DNA. This phi X A protein-[32P]DNA complex was the product of the reinitiation reaction. The phi X A protein-[32P]DNA complex could be trapped as a protein-32P-oligonucleotide complex by the inclusion of ddGTP in reaction mixtures. In this report, the structure of the phi X A protein-32P-oligonucleotide complex has been analyzed. The DNA sequence of the oligonucleotide bound to the phi X A protein has been determined and shown to be homologous to the phi X (+) strand sequence immediately adjacent (3') to the replication origin. The phi X A protein was directly linked to the 5' position of a dAMP residue of the oligonucleotide; this residue corresponded to position 4306 of the phi X DNA sequence. The phi X A protein-32P-oligonucleotide complex was exhaustively digested with either trypsin or proteinase K and the 32P-labeled proteolytic fragments were analyzed. Each protease yielded two different 32P-labeled peptides in approximately equimolar ratios. The two 32P-labeled peptides formed after digestion with trypsin (designated T1 and T2) and with proteinase K (designated PK1 and PK2) were isolated and characterized. Digestion of peptide T1 with proteinase K yielded a product which co-migrated with peptide PK2. In contrast, peptide T2 was unaffected by digestion with proteinase K. These results suggest that the phi X A protein contains two active sites that are each capable of binding covalently to DNA. The peptide-mononucleotide complexes T1-[32P]pdA and T2-[32P]pdA were isolated and subjected to acid hydrolysis in 6.0 N HCl. In each case, the major 32P-labeled products were identified as [32P] phosphotyrosine and [32P]Pi. This indicates that each active site of

  11. Preparation and Characterization of a Complex of Paeonol and ...

    African Journals Online (AJOL)

    Purpose: To improve the solubility of paeonol in water by complexing with hydroxypropyl-β-cyclodextrin and also to characterize the physicochemical properties of the complex. Methods: The complex of paeonol and HP-β-CD was prepared by freeze-drying method. Its physicochemical properties were studied by ...

  12. Solution Structures of PPARγ2/RXRα Complexes

    Directory of Open Access Journals (Sweden)

    Judit Osz

    2012-01-01

    Full Text Available PPARγ is a key regulator of glucose homeostasis and insulin sensitization. PPARγ must heterodimerize with its dimeric partner, the retinoid X receptor (RXR, to bind DNA and associated coactivators such as p160 family members or PGC-1α to regulate gene networks. To understand how coactivators are recognized by the functional heterodimer PPARγ/RXRα and to determine the topological organization of the complexes, we performed a structural study using small angle X-ray scattering of PPARγ/RXRα in complex with DNA from regulated gene and the TIF2 receptor interacting domain (RID. The solution structures reveal an asymmetry of the overall structure due to the crucial role of the DNA in positioning the heterodimer and indicate asymmetrical binding of TIF2 to the heterodimer.

  13. SYNTHESIS, CHARACTERIZATION, AND CRYSTAL STRUCTURE ...

    African Journals Online (AJOL)

    a

    organic coordination networks based on complexes of transition metals and multifunctional bridging ligands, such as polyamine and polyacid, has proven to be a fertile field due to the intriguing network topologies and potential functions as new ...

  14. Preparation and characterization of artemether inclusion complexes ...

    African Journals Online (AJOL)

    Purpose: To investigate experimentally the inclusion of artemether into the cavity of hydroxypropyl-β-cyclodextrin and examine its effect on the solubility and dissolution rate of the drug. Methods: Inclusion complexes of artemether with hydroxypropyl-β-cyclodextrin of molar ratios 1:1, 1:2 and 1:3 were prepared using the ...

  15. General study on the crystal, electronic and band structures, the morphological characterization, and the magnetic properties of the Sr{sub 2}DyRuO{sub 6} complex perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Triana, C.A.; Landínez Téllez, D.A.; Roa-Rojas, J., E-mail: jroar@unal.edu.co

    2015-01-15

    A comprehensive investigation of the general properties of the Sr{sub 2}DyRuO{sub 6} complex perovskite was undertaken. Crystal structure characterization performed by X-ray diffraction measurements and Rietveld analysis allowed establishing that the material crystallizes in a distorted monoclinic perovskite-like structure belonging to the P2{sub 1}/n (#14) space group, with alternating distribution of Dy{sup 3} {sup +} (2c: 0, 0.5, 0) and Ru{sup 5} {sup +} (2d: 0.5, 0, 0). Because of the mismatch in the ionic radii, the DyO{sub 6} and RuO{sub 6} octahedra are forced to tilt around the cubic directions so as to optimize the Sr–O inter-atomic bond lengths. Morphological characterization carried out by scanning electron microscopy indicated a particle size D = 37.17 nm and an activation energy Q = 109.8 kJ/mol. Semi-quantitative compositional study, performed through energy-dispersive X-ray experiments, corroborated that the pure phase of the Sr{sub 2}DyRuO{sub 6} was correctly obtained. Magnetic properties determined from the fit of the Curie–Weiss law to the curves of magnetic susceptibility as a function of temperature showed that Sr{sub 2}DyRuO{sub 6} exhibits an antiferromagnetic-like behavior at low temperatures as a consequence of a magnetic transition at T = 38 K. Data collected with respect to the field dependence of the magnetization showed the existence of a weak ferromagnetic moment relationship with antiferromagnetic-like behavior. Density functional theory allowed establishing the optimum electronic structure for Sr{sub 2}DyRuO{sub 6}, and the study of the density of states showed that Dy{sup 3} {sup +} and Ru{sup 5} {sup +} are responsible for the magnetic character of the compound, with the prediction that at T = 0 K it behaves as a half-metallic material. The spin magnetic moment of the cell is close to 16 μ{sub B}, and the integer number of Bohr magneton is a signature of half-metallic character. Evolution of crystal structure at high

  16. Post-structuralism, Complexity and Poetics.

    OpenAIRE

    Dillon, Michael

    2000-01-01

    Post-structuralism and complexity are plural and diverse modes of thought that share a common subscription to the �anteriority of radical relationality�. They nonetheless subscribe to a different ethic of life because they address the anteriority of radical relationality in different ways. Complexity remains strategic in its bid to become a power-knowledge of the laws of becoming. It derives that strategic ethic from its scientific interest in the implicate order of non-linearity that is ...

  17. Characterizing complex networks through statistics of Möbius transformations

    Science.gov (United States)

    Jaćimović, Vladimir; Crnkić, Aladin

    2017-04-01

    It is well-known now that dynamics of large populations of globally (all-to-all) coupled oscillators can be reduced to low-dimensional submanifolds (WS transformation and OA ansatz). Marvel et al. (2009) described an intriguing algebraic structure standing behind this reduction: oscillators evolve by the action of the group of Möbius transformations. Of course, dynamics in complex networks of coupled oscillators is highly complex and not reducible. Still, closer look unveils that even in complex networks some (possibly overlapping) groups of oscillators evolve by Möbius transformations. In this paper, we study properties of the network by identifying Möbius transformations in the dynamics of oscillators. This enables us to introduce some new (statistical) concepts that characterize the network. In particular, the notion of coherence of the network (or subnetwork) is proposed. This conceptual approach is meaningful for the broad class of networks, including those with time-delayed, noisy or mixed interactions. In this paper, several simple (random) graphs are studied illustrating the meaning of the concepts introduced in the paper.

  18. Interface areas complexity characterization of echographic images

    Energy Technology Data Exchange (ETDEWEB)

    Capri, Arnaud [LVR, Orleans University, IUT de Bourges, 63 avenue de Lattre de Tassigny, 18020 Bourges (France); SINTERS GROUP SAS, 5 rue Paul Mesple, BP 1311, 31106 ToulouseCedex 01 (France)]. E-mail: Arnaud.Capri@bourges.univ-orleans.fr; Vincent, Nicole [CRIP5-SIP, Rene Descartes University-Paris 5, 45 rue des Saints-Peres, 75270 Paris Cedex 06 (France); Vieyres, Pierre [LVR, Orleans University, IUT de Bourges, 63 avenue de Lattre de Tassigny, 18020 Bourges (France); Poisson, Gerard [LVR, Orleans University, IUT de Bourges, 63 avenue de Lattre de Tassigny, 18020 Bourges (France); Makris, Pascal [LI, University Francois Rabelais of Tours, 64 avenue Jean Portalis, 37200 Tours (France)

    2006-12-20

    The telemedicine concept integrates images, video acquisition and video transfer which are usually managed by using a standard videoconference system. Very often, the initial blur of echography pictures makes it difficult to use standard segmentation techniques such as snakes or Sobel filters which aid the doctor in making his decision. In medical echography practice, contour properties of an organ are often more relevant to decipher the presence of pathologies than the exact lineout of the contour itself. The processing, via the fuzzy approach, enables us to subdivide an image in different classes: one gathering the homogeneous zones (pixels belonging to a medium) and the other gathering more heterogeneous zones (e.g. transition between two media). Complexity measurement of each region can be approximated by the calculation of a fractal dimension. Thus, we can obtain interface complexity without having to extract the interfaces themselves. Finally, the link between fractal dimension and fuzzy rate is carried out.

  19. Three-dimensional structural characterization of nonwoven fabrics.

    Science.gov (United States)

    Venu, Lalith B Suragani; Shim, Eunkyoung; Anantharamaiah, Nagendra; Pourdeyhimi, Behnam

    2012-12-01

    Nonwoven materials are found in a gamut of critical applications. This is partly due to the fact that these structures can be produced at high speed and engineered to deliver unique functionality at low cost. The behavior of these materials is highly dependent on alignment of fibers within the structure. The ability to characterize and also to control the structure is important, but very challenging due to the complex nature of the structures. Thus, to date, focus has been placed mainly on two-dimensional analysis techniques for describing the behavior of nonwovens. This article demonstrates the utility of three-dimensional (3D) digital volumetric imaging technique for visualizing and characterizing a complex 3D class of nonwoven structures produced by hydroentanglement.

  20. Synthesis and spectroscopic characterization of dicyanamido-Cu(II) complexes. Part 2 : Crystal structure of the complexes of tris[2-(2-pyridylethyl)]amine, tris(2-pyridylmethyl)amine and 1,4-bis[2-(2-pyridylethyl)]piperazine

    Science.gov (United States)

    Mautner, Franz A.; Soileau, Jesse B.; Bankole, Paul K.; Gallo, August A.; Massoud, Salah S.

    2008-10-01

    Two classes of novel dicyanamido (dca)-Cu(II) complexes were synthesized with a variety of tetradentate tripod amines, tridentate amines and diazacycloalkanes with pyridyl arms of different alkyl lengths and with tetra-aza macrocycles with different cavity sizes; the mononuclear, Cu(L)(dca)]ClO 4 (L = tepa ( 1), TPA ( 2), pzdepy ( 4), hpzpy 2 ( 5), cyclen ( 7), cyclam ( 8), tacp ( 9)) or Cu(L)(dca)ClO 4 (L = MeDPA ( 10), Mepea ( 11)) and the dinuclear, [Cu 2(L') 2(dca)](ClO 4) 3 (L' = pmap ( 3), pzpy 2 ( 6)). The isolated complexes were structurally characterized by electronic and IR spectroscopy as well as by X-ray. Single crystal X-ray diffraction analysis of the complexes [Cu(tepa)(dca)]ClO 4 ( 1), [Cu(TPA)(dca)]ClO 4 ( 2) and [Cu(pzdepy)(dca)]ClO 4 ( 4) reveal their monomeric penta-coordinate nature with the isolated [Cu(L)(dca)] + cations and ClO4- counter ions. All the complexes with the exception of 2 adapt distorted square pyramidal geometry while the coordination polyhedron around the copper center in 2 may be described as a distorted trigonal bipyramidal stereochemistry. The visible spectra of the complexes in aqueous solutions or in methanol are in complete agreement with the assigned X-ray geometry around the Cu(II) centers.

  1. Learning Latent Structure in Complex Networks

    DEFF Research Database (Denmark)

    Mørup, Morten; Hansen, Lars Kai

    Latent structure in complex networks, e.g., in the form of community structure, can help understand network dynamics, identify heterogeneities in network properties, and predict ‘missing’ links. While most community detection algorithms are based on optimizing heuristic clustering objectives...... prediction performance of the learning based approaches and other widely used link prediction approaches in 14 networks ranging from medium size to large networks with more than a million nodes. While link prediction is typically well above chance for all networks, we find that the learning based mixed...... membership stochastic block model of Airoldi et al., performs well and often best in our experiments. The added complexity of the LD model improves link predictions for four of the 14 networks....

  2. Characterization of Hematopoietic Transcription Factor Complexes in Erythroid Cells

    NARCIS (Netherlands)

    P.J.F. Rodriguez

    2006-01-01

    textabstractEfficient tagging methodologies are an integral aspect of protein complex characterization by proteomic approaches. Due to biotin’s very high affinity for avidin and streptavidin, biotinylation tagging offers an attractive approach for the efficient purification of protein

  3. Synthesis, characterization, X-ray crystal structure, electrochemical ...

    Indian Academy of Sciences (India)

    DOI 10.1007/s12039-015-0978-8. Synthesis, characterization, X-ray crystal structure, electrochemical evaluation and anti-cancer studies of a mixed ligand Cu(II) complex of (E)-N -((2-hydroxynaphthalen-1-yl)methylene)acetohydrazide. IRAN SHEIKHSHOAIEa, S YOUSEF EBRAHIMIPOURa,∗, MAHDIEH SHEIKHSHOAIEa,.

  4. Synthesis, structural characterization and biological activity of a ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 125; Issue 6. Synthesis, structural characterization and biological activity of a trinuclear zinc(II) complex: DNA interaction study and antimicrobial activity. Bhaskar Biswas Niranjan Kole Moumita Patra Shampa Dutta Mousumi Ganguly. Regular Articles Volume 125 ...

  5. Synthesis, characterization and crystal structure of new nickel ...

    Indian Academy of Sciences (India)

    Abstract. A novel nickel molybdenum complex with the 2,6-pyridine dicarboxylic acid ligand was successfully synthesized and characterized by thermogravimetric analysis and single crystal X-ray crystallography. The single-crystal X-ray data revealed that the structure is a hydrated 1-D polymer with two different Ni sites.

  6. Syntheses, characterization and crystal structures of potassium and ...

    Indian Academy of Sciences (India)

    Syntheses, characterization and crystal structures of potassium and barium complexes of a Schiff base ligand with different anions. Bhavesh Parmar Kamal Kumar Bisht Pratyush Maiti Parimal Paul Eringathodi Suresh. Special issue on Chemical Crystallography Volume 126 Issue 5 September 2014 pp 1373-1384 ...

  7. Syntheses, characterization and crystal structures of potassium and ...

    Indian Academy of Sciences (India)

    Syntheses, characterization and crystal structures of potassium and barium complexes of a Schiff base ligand with different anions. BHAVESH PARMARa, KAMAL KUMAR BISHTa,b, PRATYUSH MAITIc, PARIMAL PAULa,b, and ERINGATHODI SURESHa,b,∗. aAnalytical Discipline and Centralized Instrument Facility, ...

  8. Complexing mechanism of the lanthanide cations Eu3+, Gd3+, and Tb3+ with 1,4,7,10-tetrakis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (dota)-characterization of three successive complexing phases: study of the thermodynamic and structural properties of the complexes by potentiometry, luminescence spectroscopy, and EXAFS.

    Science.gov (United States)

    Moreau, Juliette; Guillon, Emmanuel; Pierrard, Jean-Claude; Rimbault, Jean; Port, Marc; Aplincourt, Michel

    2004-10-11

    Complexation of the lanthanides Eu3+, Gd3+, and Tb3+ with 1,4,7,10-tetrakis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (dota) has been studied in solution by using potentiometry, luminescence spectrometry, and EXAFS. Three series of successive complexes were characterized by at least two of these methods: the immediate [LnHn(dota)](n-1)+** and intermediate [LnHn(dota)](n-1)+* complexes with 0 potentiometry. From the results, a complexation mechanism involving three steps has been proposed. In the [LnHn(dota)](n-1)+** complexes that are instantaneously formed, the lanthanide is bound to four oxygen atoms of the carboxylate groups and to five water molecules. These species evolve rapidly: the lanthanide moves into the macrocycle cavity, two new bonds are formed with two nitrogen atoms diametrically opposed in the tetraaza cycle and only three water molecules remain bound to the lanthanide in the [LnHn(dota)](n-1)+* (0 complexes, which appear after a two-day wait. These compounds are stable for about four days. After 4-8 weeks, a concerted rearrangement occurs which leads to the formation of thermodynamically stable [Ln(dota)]- complexes in which the lanthanide is bound to four nitrogen atoms, four carboxylate oxygen atoms, and one water molecule.

  9. Structures of the CRISPR genome integration complex.

    Science.gov (United States)

    Wright, Addison V; Liu, Jun-Jie; Knott, Gavin J; Doxzen, Kevin W; Nogales, Eva; Doudna, Jennifer A

    2017-09-15

    CRISPR-Cas systems depend on the Cas1-Cas2 integrase to capture and integrate short foreign DNA fragments into the CRISPR locus, enabling adaptation to new viruses. We present crystal structures of Cas1-Cas2 bound to both donor and target DNA in intermediate and product integration complexes, as well as a cryo-electron microscopy structure of the full CRISPR locus integration complex, including the accessory protein IHF (integration host factor). The structures show unexpectedly that indirect sequence recognition dictates integration site selection by favoring deformation of the repeat and the flanking sequences. IHF binding bends the DNA sharply, bringing an upstream recognition motif into contact with Cas1 to increase both the specificity and efficiency of integration. These results explain how the Cas1-Cas2 CRISPR integrase recognizes a sequence-dependent DNA structure to ensure site-selective CRISPR array expansion during the initial step of bacterial adaptive immunity. Copyright © 2017, American Association for the Advancement of Science.

  10. Characterization of complex networks : Application to robustness analysis

    NARCIS (Netherlands)

    Jamakovic, A.

    2008-01-01

    This thesis focuses on the topological characterization of complex networks. It specifically focuses on those elementary graph measures that are of interest when quantifying topology-related aspects of the robustness of complex networks. This thesis makes the following contributions to the field of

  11. Characterizing Asteroid Internal Structure Through Tectonic Analyses

    Science.gov (United States)

    Wyrick, D. Y.; Buczkowski, D. L.; Durda, D. D.

    2017-02-01

    Critical data gaps remain in characterizing the mechanical strength and internal structure of asteroids. Understanding asteroid internal coherency is required to develop effective mitigation, diversion, or destruction strategies against impact threat.

  12. Chiral PEPPSI Complexes: Synthesis, Characterization, and Application in Asymmetric Suzuki–Miyaura Coupling Reactions

    KAUST Repository

    Benhamou, Laure

    2014-01-13

    PEPPSI complexes incorporating chiral N-heterocyclic carbene (NHC) ligands based on 2,2-dimethyl-1-(o-substituted aryl)propan-1-amines were synthesized. Two complexes, with one saturated and one unsaturated NHC ligand, were structurally characterized. The chiral PEPPSI complexes were used in asymmetric Suzuki-Miyaura reactions, giving atropisomeric biaryl products in modest to good enantiomeric ratios. © 2013 American Chemical Society.

  13. The complex channel networks of bone structure

    CERN Document Server

    Costa, Luciano da Fontoura; Beletti, Marcelo E

    2006-01-01

    Bone structure in mammals involves a complex network of channels (Havers and Volkmann channels) required to nourish the bone marrow cells. This work describes how three-dimensional reconstructions of such systems can be obtained and represented in terms of complex networks. Three important findings are reported: (i) the fact that the channel branching density resembles a power law implies the existence of distribution hubs; (ii) the conditional node degree density indicates a clear tendency of connection between nodes with degrees 2 and 4; and (iii) the application of the recently introduced concept of hierarchical clustering coefficient allows the identification of typical scales of channel redistribution. A series of important biological insights is drawn and discussed

  14. Electronic structure and magnetism of complex materials

    CERN Document Server

    Papaconstantopoulos, D A

    2003-01-01

    Recent developments in electronic structure theory have led to a new understanding of magnetic materials at the microscopic level. This enables a truly first-principles approach to investigations of technologically important magnetic materials. Among these advances have been practical schemes for handling non-collinear magnetic systems, including relativity, understanding of the origins and role of orbital magnetism within band structure formalisms, density functional approaches for magnons and low-lying spin excitations, understanding of the interplay of orbital, spin and lattice orderings in complex oxides, transport theories for layered systems, and the theory of magnetic interactions in doped semiconductors. The book covers these recent developments with review articles by some of the main originators of these advances.

  15. On characterization of anisotropic plant protein structures

    NARCIS (Netherlands)

    Krintiras, G.A.; Göbel, J.; Bouwman, W.G.; Goot, van der A.J.; Stefanidis, G.D.

    2014-01-01

    In this paper, a set of complementary techniques was used to characterize surface and bulk structures of an anisotropic Soy Protein Isolate (SPI)–vital wheat gluten blend after it was subjected to heat and simple shear flow in a Couette Cell. The structured biopolymer blend can form a basis for a

  16. Fabrication and characterization of woodpile structures

    DEFF Research Database (Denmark)

    Zalkovskij, Maksim; Malureanu, Radu; Andryieuski, Andrei

    2011-01-01

    In this paper we present the whole fabrication and characterization cycle for obtaining 3D metal-dielectric woodpile structures. The optical properties of these structures have been measured using different setups showing the need of considering e.g. border effects when planning their use in real...

  17. Synthesis and crystal structure of a polymeric zinc(II) complex ...

    African Journals Online (AJOL)

    A new polymeric zinc(II) complex, [ZnL2(PDA)]n, has been prepared by the reaction of zinc sulfate, 4-nitrophenylacetic acid, and propane-1,3-diamine (PDA) in water. Structure of the complex has been characterized by single-crystal X-ray diffraction. The complex crystallizes as orthorhombic space group Pnma, with unit cell ...

  18. Health Monitoring for Airframe Structural Characterization

    Science.gov (United States)

    Munns, Thomas E.; Kent, Renee M.; Bartolini, Antony; Gause, Charles B.; Borinski, Jason W.; Dietz, Jason; Elster, Jennifer L.; Boyd, Clark; Vicari, Larry; Ray, Asok; hide

    2002-01-01

    This study established requirements for structural health monitoring systems, identified and characterized a prototype structural sensor system, developed sensor interpretation algorithms, and demonstrated the sensor systems on operationally realistic test articles. Fiber-optic corrosion sensors (i.e., moisture and metal ion sensors) and low-cycle fatigue sensors (i.e., strain and acoustic emission sensors) were evaluated to validate their suitability for monitoring aging degradation; characterize the sensor performance in aircraft environments; and demonstrate placement processes and multiplexing schemes. In addition, a unique micromachined multimeasure and sensor concept was developed and demonstrated. The results show that structural degradation of aircraft materials could be effectively detected and characterized using available and emerging sensors. A key component of the structural health monitoring capability is the ability to interpret the information provided by sensor system in order to characterize the structural condition. Novel deterministic and stochastic fatigue damage development and growth models were developed for this program. These models enable real time characterization and assessment of structural fatigue damage.

  19. Curcumin complexation with cyclodextrins by the autoclave process: Method development and characterization of complex formation.

    Science.gov (United States)

    Hagbani, Turki Al; Nazzal, Sami

    2017-03-30

    One approach to enhance curcumin (CUR) aqueous solubility is to use cyclodextrins (CDs) to form inclusion complexes where CUR is encapsulated as a guest molecule within the internal cavity of the water-soluble CD. Several methods have been reported for the complexation of CUR with CDs. Limited information, however, is available on the use of the autoclave process (AU) in complex formation. The aims of this work were therefore to (1) investigate and evaluate the AU cycle as a complex formation method to enhance CUR solubility; (2) compare the efficacy of the AU process with the freeze-drying (FD) and evaporation (EV) processes in complex formation; and (3) confirm CUR stability by characterizing CUR:CD complexes by NMR, Raman spectroscopy, DSC, and XRD. Significant differences were found in the saturation solubility of CUR from its complexes with CD when prepared by the three complexation methods. The AU yielded a complex with expected chemical and physical fingerprints for a CUR:CD inclusion complex that maintained the chemical integrity and stability of CUR and provided the highest solubility of CUR in water. Physical and chemical characterizations of the AU complexes confirmed the encapsulated of CUR inside the CD cavity and the transformation of the crystalline CUR:CD inclusion complex to an amorphous form. It was concluded that the autoclave process with its short processing time could be used as an alternate and efficient methods for drug:CD complexation. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Catechol oxidase activity of a series of new dinuclear copper(II) complexes with 3,5-DTBC and TCC as substrates: syntheses, X-ray crystal structures, spectroscopic characterization of the adducts and kinetic studies.

    Science.gov (United States)

    Banu, Kazi Sabnam; Chattopadhyay, Tanmay; Banerjee, Arpita; Bhattacharya, Santanu; Suresh, Eringathodi; Nethaji, Munirathinam; Zangrando, Ennio; Das, Debasis

    2008-08-18

    A series of dinuclear copper(II) complexes has been synthesized with the aim to investigate their applicability as potential structure and function models for the active site of catechol oxidase enzyme. They have been characterized by routine physicochemical techniques as well as by X-ray single-crystal structure analysis: [Cu 2(H 2L2 (2))(OH)(H 2O)(NO 3)](NO 3) 3.2H 2O ( 1), [Cu(HL1 (4))(H 2O)(NO 3)] 2(NO 3) 2.2H 2O ( 2), [Cu(L1 (1))(H 2O)(NO 3)] 2 ( 3), [Cu 2(L2 (3))(OH)(H 2O) 2](NO 3) 2, ( 4) and [Cu 2(L2 (1))(N 3) 3] ( 5) [L1 = 2-formyl-4-methyl-6R-iminomethyl-phenolato and L2 = 2,6-bis(R-iminomethyl)-4-methyl-phenolato; for L1 (1) and L2 (1), R = N-propylmorpholine; for L2 (2), R = N-ethylpiperazine; for L2 (3), R = N-ethylpyrrolidine, and for L1 (4), R = N-ethylmorpholine]. Dinuclear 1 and 4 possess two "end-off" compartmental ligands with exogenous mu-hydroxido and endogenous mu-phenoxido groups leading to intermetallic distances of 2.9794(15) and 2.9435(9) A, respectively; 2 and 3 are formed by two tridentate compartmental ligands where the copper centers are connected by endogenous phenoxido bridges with Cu-Cu separations of 3.0213(13) and 3.0152(15) A, respectively; 5 is built by an end-off compartmental ligand having exogenous mu-azido and endogenous mu-phenoxido groups with a Cu-Cu distance of 3.133(2) A (mean of two independent molecules). The catecholase activity of all of the complexes has been investigated in acetonitrile and methanol medium by UV-vis spectrophotometric study using 3,5-di- tert-butylcatechol (3,5-DTBC) and tetrachlorocatechol (TCC) as substrates. In acetonitrile medium, the conversion of 3,5-DTBC to 3,5-di- tert-butylbenzoquinone (3,5-DTBQ) catalyzed by 1- 5 is observed to proceed via the formation of two enzyme-substrate adducts, ES1 and ES2, detected spectroscopically for the first time. In methanol medium no such enzyme-substrate adduct has been detected, and the 3,5-DTBC to 3,5-DTBQ conversion is observed to be catalyzed by 1- 5

  1. ELASTICITY:Topological characterization of robustness in complex networks

    NARCIS (Netherlands)

    Sydney, A.; Scoglio, C.; Schumm, P.; Kooij, R.E.

    2008-01-01

    Just as a herd of animals relies on its robust social structure to survive in the wild, similarly robustness is a crucial characteristic for the survival of a complex network under attack. The capacity to measure robustness in complex networks defines a network's survivability in the advent of

  2. Topological Characterization of Complex Systems: Using Persistent Entropy

    NARCIS (Netherlands)

    Merelli, E.; Rucco, M.; Sloot, P.; Tesei, L.

    2015-01-01

    In this paper, we propose a methodology for deriving a model of a complex system by exploiting the information extracted from topological data analysis. Central to our approach is the S[B] paradigm in which a complex system is represented by a two-level model. One level, the structural S one, is

  3. Synthesis and Characterization of Copper (II) Complex of Glycine ...

    African Journals Online (AJOL)

    Copper(II)Complex of amino acid was synthesized by refluxing the mixtures of ethanolic solutions of glycine and copper(II)chloride. The complex compound was characterized by melting point (225oC), PH 5.78 at 28oC, moisture content of 5% with a yield of 68%. The compound is insoluble in water but readily soluble in ...

  4. New mixed ligand palladium(II) complexes based on the antiepileptic drug sodium valproate and bioactive nitrogen-donor ligands: synthesis, structural characterization, binding interactions with DNA and BSA, in vitro cytotoxicity studies and DFT calculations.

    Science.gov (United States)

    Tabrizi, Leila; Chiniforoshan, Hossein; Tavakol, Hossein

    2015-04-15

    The complexes [Pd(valp)2(imidazole)2] (1), [Pd(valp)2(pyrazine)2] (2) (valp is sodium valproate) have been synthesized and characterized using IR, (1)H NMR, (13)C{(1)H} NMR and UV-Vis spectrometry. The interaction of complexes with CT-DNA has been investigated using spectroscopic tools and viscosity measurement. In each case, the association constant (Kb) was deduced from the absorption spectral study and the number of binding sites (n) and the binding constant (K) were calculated from relevant fluorescence quenching data. As a result, a non-covalent interaction between the metal complex and DNA was suggested, which could be assigned to an intercalative binding. In addition, the interaction of 1 and 2 was ventured with bovine serum albumin (BSA) with the help of absorption and fluorescence spectroscopy measurements. Through these techniques, the apparent association constant (Kapp) and the binding constant (K) could be calculated for each complex. Evaluation of cytotoxic activity of the complexes against four different cancer cell lines proved that the complexes exhibited cytotoxic specificity and significant cancer cell inhibitory rate. Moreover, density functional theory (DFT) calculations were employed to provide more evidence about the observed data. The majority of trans isomers were supported not only by energies, but also by the similarity of its calculated IR frequencies, UV adsorptions and NMR chemical shifts to the experimental values. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Synthesis, characterization and thermal properties of palladium(II complexes containing phenyltetrazole. Crystal structure of trans-[C40H64N8 O2PdCl2

    Directory of Open Access Journals (Sweden)

    Gallardo Hugo

    2000-01-01

    Full Text Available The new 5-(n-alkoxyphenyl-2-n-alkyltetrazole (L¹ and alpha,omega-bis-[5-(4-pentoxyphenyl-2-alkanetetrazoles] (L² ligands and their Pd(II complexes have been synthesized. The X-ray diffraction study of the palladium complex with L¹ reveals a mononuclear structure in which the geometry of the Pd(L¹2Cl2 chromophore is planar as required by the inversion center at the palladium atom, where each molecule of phenyltetrazole binds to the metal ion in a monodentate fashion via a Pd-N1 sigma-bond. For the palladium complex with L², a dinuclear structure ([Pd2(L²2Cl4 ] has been proposed on the basis of NMR and IR spectroscopy.

  6. Identifying community structure in complex networks

    Science.gov (United States)

    Shao, Chenxi; Duan, Yubing

    2015-07-01

    A wide variety of applications could be formulated to resolve the problem of finding all communities from a given network, ranging from social and biological network analysis to web mining and searching. In this study, we propose the concept of virtual attractive strength between each pair of node in networks, and then give the definition of community structure based on the proposed attractive strength. Furthermore, we present a community detection method by moving vertices to the clusters that produce the largest attractive strengths to them until the division of network reaches unchanged. Experimental results on synthetic and real networks indicate that the proposed approach has favorite effectiveness and fast convergence speed, which provides an efficient method for exploring and analyzing complex systems.

  7. Structural studies of supramolecular photochemical beta-cyclodextrin inclusion complexes

    Science.gov (United States)

    Brett, Thomas John

    X-ray crystallography has played an essential role in our understanding of the factors controlling the outcomes of solid-state photochemical reactions. The detailed and systematic study of supramolecular photochemical systems is not very common. The dissertation research described here was designed to help fill this deficit. beta-cyclodextrin (beta-CD) is an example of a host molecule which has been used as a host to photochemical reactions. An important influence on the outcome of the solid state reaction is the surrounding crystalline environment. Structural studies of beta-CD inclusion complexes with derivatized biphenyl molecules, biphenyl and p-amino-p '-nitrobiphenyl, characterize the beta-CD dimer environment as non-constraining. Both molecules exhibit twisted conformations within the beta-CD dimer, identical to their conformations displayed in the gas phase. The photodimerization of various coumarins in crystalline beta-CD complexes was studied in detail. The beta-CD/coumarin complex was found to be a 2:3 host:guest (H:G) complex in contradiction to previous literature reports. The beta-CD dimers stack in long channels with the coumarin molecules stacked one on top of another inside creating a reaction nano-tube in which the theoretical yield is limited to 67%. The photodimerization of 7-hydroxy-4-methylcoumarin in its crystalline beta-CD inclusion complex was directly observed by X-ray diffraction. Examination of the structure of an unreacted crystal and one that was irradiated for 6 days revealed that the reaction proceeds in a topochemical fashion within the beta-CD dimer cavity. The beta-CD dimers arrange in a manner which creates isolated reaction nano-vessels throughout the crystal. The structure of the beta-CD/7-hydroxycoumarin complex shows that this complex is nearly identical the beta-CD/7-hydroxy-4-methylcoumarin complex despite the looser spatial fit of the guest to the cavity. The studies of the beta-CD/4,7-dimethylcoumarin complex produced

  8. Characterization of Structure and Damage in Materials in Four Dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, I. M. [Univ. of Illinois, Urbana, IL (United States); Schuh, C. A. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Vetrano, J. S. [U.S. Department of Energy, Washington, DC (United States); Browning, N. D. [Univ. of California, Davis, CA (United States); Field, D. P. [Washington State Univ., Pullman, WA (United States); Jensen, D. J. [Technical Univ. of Denmark, Roskilde (Denmark); Miller, M. K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Baker, I. [Darmouth College, Hanover, NH (United States); Dunand, D. C. [Northwestern Univ., Evanston, IL (United States); Dunin-Borkowski, R. [Technical Univ. of Denmark, Lyngby (Denmark); Kabius, B. [Argonne National Lab. (ANL), Argonne, IL (United States); Kelly, T. [Cameca Instruments Corp., Madison, WI (United States); Lozano-Perez, S. [Univ. of Oxford (United Kingdom); Misra, A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rohrer, G. S. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Rollett, A. D. [Carnegie Mellon Univ., Pittsburgh, PA (United States); Taheri, M. [Drexel Univ., Philadelphia, PA (United States); Thompson, G. B. [Univ. of Alabama, Tuscaloosa, AL (United States); Uchic, M. [Air Force Research Lab. (AFRL), Wright-Patterson AFB, OH (United States); Wang, X. L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Was, G. [Univ. of Michigan, Ann Arbor, MI (United States)

    2010-09-30

    The materials characterization toolbox has recently experienced a number of parallel revolutionary advances, foreshadowing a time in the near future when materials scientists can quantify material structure across orders of magnitude in length and time scales (i.e., in four dimensions) completely. This paper presents a viewpoint on the materials characterization field, reviewing its recent past, evaluating its present capabilities, and proposing directions for its future development. Electron microscopy; atom-probe tomography; X-ray, neutron and electron tomography; serial sectioning tomography; and diffraction-based analysis methods are reviewed, and opportunities for their future development are highlighted. Particular attention is paid to studies that have pioneered the synergetic use of multiple techniques to provide complementary views of a single structure or process; several of these studies represent the state-of-the-art in characterization, and suggest a trajectory for the continued development of the field. Based on this review, a set of grand challenges for characterization science is identified, including suggestions for instrumentation advances, scientific problems in microstructure analysis, and complex structure evolution problems involving materials damage. The future of microstructural characterization is proposed to be one not only where individual techniques are pushed to their limits, but where the community devises strategies of technique synergy to address complex multiscale problems in materials science and engineering.

  9. Advanced Structural Characterization of Organic Thin Films

    DEFF Research Database (Denmark)

    Gu, Yun

    In this thesis, the structural characterizations of three organic film systems are described. Several X-ray based techniques have been utilized for the characterizations for different research goals. The structures of N,N',N-trioctyltriazatriangulenium (Oct3-TATA+) salts have been investigated...... of small molecule and polymer layers is indicated by Flory- Huggins theory for the triisopropylsilylethynl pentacene (TIPS-PEN) and polystyrene blend films. In order to investigate the phase separated layers in the ink-jet printed films, we propose a method to measure diraction Bragg peaks by X...

  10. Transition metal complexes of neocryptolepine analogues. Part I: Synthesis, spectroscopic characterization, and invitro anticancer activity of copper(II) complexes

    Science.gov (United States)

    Emam, Sanaa Moustafa; El Sayed, Ibrahim El Tantawy; Nassar, Nagla

    2015-03-01

    New generation of copper(II) complexes with aminoalkylaminoneocryptolepine as bidentate ligands has been synthesized and it is characterized by elemental analyses, magnetic moment, spectra (IR, UV-Vis, 1H NMR and ESR) and thermal studies. The IR data suggest the coordination modes for ligands which behave as a bidentate with copper(II) ion. Based on the elemental analysis, magnetic studies, electronic and ESR data, binuclear square planar geometry was proposed for complexes 7a, 7b, square pyramidal for 9a, 9b and octahedral for 8a, 8b, 10a, 10b. The molar conductance in DMF solution indicates that all complexes are electrolyte except 7a and 7b. The ESR spectra of solid copper(II) complexes in powder form showed an axial symmetry with 2B1g as a ground state and hyperfine structure. The thermal stability and degradation of the ligands and their metal complexes were studied employing DTA and TG methods. The metal-free ligands and their copper(II) complexes were tested for their in vitro anticancer activity against human colon carcinoma (HT-29). The results showed that the synthesized copper(II) complexes exhibited higher anticancer activity than their free ligands. Of all the studied copper(II) complexes, the bromo-substituted complex 9b exhibited high anticancer activity at low micromolar inhibitory concentrations (IC50 = 0.58 μM), compared to the other complexes and the free ligands.

  11. Síntese e caracterização estrutural do ligante isatina-3-(N4-benziltiossemicarbazona e do seu complexo de mercúrio(II Synthesis and structural characterization of the ligand isatin-3-(N4-benzylthiosemicarbazone and its mercury(II complex

    Directory of Open Access Journals (Sweden)

    Alexandra de Souza Fonseca

    2010-01-01

    Full Text Available The reaction of 4-(phenylthiosemicarbazide with isatin yielded a new ligand, isatin-3-(N4-benzylthiosemicarbazone. Isatin-3-(N4-benzylthiosemicarbazone deprotonated in ethanol/KOH reacts with an ethanolic solution of Hg(NO32 to give a mercury complex. The compounds were characterized by IR and X-ray single crystal structure determination. The X-ray studies revealed that the complex possesses a tetrahedral geometry with two deprotonated thiosemicarbazone ligands coordenated. The ligand and its mercury complex crystallize in the monoclinic (P2(1/c and triclinic (P-1 crystal system, respectively.

  12. Vortex structure and characterization of quasiperiodic functions

    CERN Document Server

    Dana, I

    2002-01-01

    Quasiperiodic functions (QPFs) are characterized by their full vortex structure in one unit cell. This characterization is much finer and more sensitive than the topological one given by the total vorticity per unit cell (the 'Chern index'). It is shown that QPFs with an arbitrarily prescribed vortex structure exist by constructing explicitly such a 'standard' QPF. Two QPFs with the same vortex structure are equivalent, in the sense that their ratio is a function which is strictly periodic, nonvanishing and at least continuous. A general QPF can then be approximately reconstructed from its vortex structure on the basis of the standard QPF and the equivalence concept. As another application of this concept, a simple method is proposed for calculating the quasiperiodic eigenvectors of periodic matrices. Possible applications to the quantum-chaos problem on a phase-space torus are briefly discussed.

  13. Organization structures for dealing with complexity

    NARCIS (Netherlands)

    Meijer, B.R.

    2006-01-01

    "Complexity is in the eye of the beholder" is a well known quote in the research field of complexity. In the world of managers the word complex is often a synonym for difficult, complicated, involving many factors and highly uncertain. A complex business decision requires careful preparation and

  14. Characterizing subsurface complexity of aeolian morphotypes with georadar

    Science.gov (United States)

    Bentley, Andrew Phillip Keller

    Aeolian landforms are classified based on their plan morphology, which is a function of sediment transport volume, wind direction, and vegetation. In the case of compound landforms or two-dimensional exposures (outcrops), there is insufficient information for discriminating between 3D morphotypes (e.g., barchans vs. parabolic dunes). To characterize the dip-section architecture of near end-member morphologies (interacting barchans and sparsely vegetated parabolics), a series of axial transects were selected from >25 km of high-resolution (500 MHz) ground-penetrating radar (GPR) data from the gypsum dune field of White Sands National Monument, New Mexico. For dunes of comparable size (6-7 m high), a series of attributes were analyzed for unsaturated portions along the thickest (axial) radargram sections. Given the limitations in vertical resolution (7 cm in dry sand), the average measureable slipface thickness in barchans ranged between 10-22 cm, whereas parabolic slipfaces were thinner at 10-14 cm. High-amplitude diffractions produced by buried vegetation, semi-lithified pedestals, and bioturbation structures were rare within barchans (point-source diffraction density = 0.03/m2; hyperbolics per 1-m-wide cross-sectional area of the image), in contrast to a point-source density of 0.07/m2 in parabolics. An aeolian internal complexity threshold (pi) is proposed, which incorporates standardized scores of slipface thickness, point-source diffraction density, and continuity of major bounding surfaces at mesoscale range determined through semivariogram analysis. For the study region, these variables were sufficient for discriminating barchans (pi = -2.39 to -0.25; pib= -1.65) from parabolic (pi = 0.13 to 2.87; pip= 1.65) dunes. This threshold has the potential for differentiating dune morphotypes in areas where surface morphology is masked and for identifying compound landforms (e.g., a re-activated parabolic dune converted into a barchan in situ ). Ultimately

  15. Synthesis and characterization of mixed ligand complexes of Zn (II ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 117; Issue 3. Synthesis and characterization of mixed ligand complexes of Zn(II) and Co(II) with amino acids: Relevance to zinc binding sites in zinc fingers. P Rabindra Reddy M Radhika P Manjula. Volume 117 Issue 3 May 2005 pp 239-246 ...

  16. Synthesis and Characterization of a Schiff Base Cobalt (III) Complex ...

    African Journals Online (AJOL)

    2017-12-18

    Dec 18, 2017 ... Synthesis and Characterization of a Schiff Base Cobalt (III) Complex and. Assessment of its Anti-Cancer Activity. Gwaram, N. S.. Department of Pure and Industrial Chemistry, Umaru Musa Yar'Adua University. P.M.B. 2211, Katsina, ... compounds of cobalt, copper, nickel, manganese, zinc, palladium ...

  17. synthesis and spectra characterization of mixed- ligand complexes ...

    African Journals Online (AJOL)

    BARTH EKWUEME

    “Let's Twist Again”-Double-Stranded,. Triple-Stranded, and Circular Helicates. Chemical Reviews 101(11): 3457-3498. Belfrekh, N., Dietrich-Buchecker, C. and Sauvage, J. P.. 2000. Synthesis and Characterization of Dinuclear Metal. Complexes Stabilized by Tetradentate Schiff base ligands.Inorganic Chemistry 39: 5169-.

  18. Structural characterization of human Uch37

    Energy Technology Data Exchange (ETDEWEB)

    Burgie, E. Sethe; Bingman, Craig A.; Soni, Ameet B.; Phillips, Jr., George N. (UW)

    2012-06-28

    Uch37 is a deubiquitylating enzyme (DUB) that is functionally linked with multiple protein complexes and signal transduction pathways. Uch37 associates with the 26S proteasome through Rpn13 where it serves to remove distal ubiquitin moeities from polyubiquitylated proteins. Uch37's proteasome associated activity was shown to liberate proteins from destruction. However, Uch37 may also specifically facilitate the destruction of inducible nitric oxide synthase and I{kappa}B-{alpha} at the proteasome. Wicks et al. established Uch37's potential to modulate the transforming growth factor-{beta}(TGF-{beta}) signaling cascade, through tis interaction with SMAD7. Yao et al. demonstrated that Uch37 also associates with the Ino80 chromatin-remodeling complex (Ino80 complex), which is involved in DNA repair and transcriptional regulation. Uch37's importance in metazoan development was underscored recently as Uch37 knockouts in mice result in prenatal lethality, where mutant embryos had severe defects in brain development. Protein ubiquitylation is an ATP-dependent post-translational modification that serves to signal a wide variety of cellular processes in eukaryotes. A protein cascade, generally comprising three enzymes, functions to activate, transport and specifically transfer ubiquitin to the targeted protein, culminating in an isopeptide linkage between the {epsilon}-amino group of a target protein's lysysl residue and the ubiquitin's terminal carboxylate. Monoubiquitination plays an important role in histone regulation, endocytosis, and viral budding. Further processing of the target protein may be accomplished by ubiquitylation of the protein on a different lysine, or through the formation of polyubiquitin chains, where the best-characterized outcome is destruction of the polyubiquitin-labeled protein in the proteasome. DUBs catalyze the removal of ubiquitin from proteins. This activity serves to reverse the effects of ubiquitination, permit

  19. Synthesis, structural characterization and biological activities of ...

    Indian Academy of Sciences (India)

    , 1H, 13C and 119Sn NMR spectral studies. The molecular structure of complex 5 has been confirmed by single ... Rosenani A Haque1 M A Salam1. The School of Chemical Sciences, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia ...

  20. Preparation and characterization of debranched-starch/phosphatidylcholine inclusion complexes.

    Science.gov (United States)

    Cheng, Weiwei; Luo, Zhigang; Li, Lin; Fu, Xiong

    2015-01-21

    In this study, debranched-starch/phosphatidylcholine inclusion complexes were prepared. The effect of reaction parameters such as reaction temperature, reaction time, and addition amount of phosphatidylcholine on the phosphatidylcholine payload and inclusion rate was investigated. The phosphatidylcholine payload and inclusion rate prepared under the optimal conditions were 106 mg/g and 84.8%, respectively. The formation of debranched-starch/phosphatidylcholine inclusion complexes was confirmed by the results of XRD and FT-IR. Furthermore, the molecular, cluster, and fractal structures of the complexes were investigated using (13)C CP/MAS NMR and SAXS. The results indicated that the inclusion complexes were formed by hydrophobic interactions between alkyl chain of phosphatidylcholine and debranched-starch helix cavity. The complexes possessed a mass fractal structure, and a semicrystalline structure with a Bragg distance of 19.04 nm formed. After complexation, the stability of phosphatidylcholine was significantly improved, and phosphatidylcholine of the complexes can be gradually released with pancreatin treatment. This study revealed that debranched-starch can be used as an effective carrier of phosphatidylcholine for the purpose of improving its stability.

  1. Synthesis, characterization and crystal structures of two discrete Cu(II) complexes with mixed-ligands: [Cu(mal)(L)(H2O)]·H2O and [Cu(Phmal)(L)2] (mal=malonate dianion, phmal=phenylmalonate dianion and L=5,5‧-dimethyl-2,2‧-bipyridine)

    Science.gov (United States)

    Cui, Guang-Hua; Li, Jian-Rong; Hu, Tong-Liang; Bu, Xian-He

    2005-03-01

    Two new Cu(II) complexes with mixed ligands, [Cu(mal)( L)(H 2O)]·H 2O ( 1) and [Cu(phmal)( L)] 2 ( 2) (mal=malonate dianion, phmal=phenylmalonate dianion, L=5,5'-dimethyl-2,2'-bipyridine) have been synthesized and characterized by elemental analyses, IR, UV-vis and X-ray single crystal diffraction. In both complexes the Cu(II) ions take five-coordinated square pyramidal geometry. 1 has a mononuclear structure, and assembles into a 2D supramolecular network by hydrogen bonding. 2 is a dinuclear complex, and also forms 2D framework via π-π interactions. The structural differences of the two complexes may be attributed to the variation of the substituted group of malonate dianion.

  2. Synthesis, characterization and antimicrobial studies of Schiff base complexes

    Science.gov (United States)

    Zafar, Hina; Ahmad, Anis; Khan, Asad U.; Khan, Tahir Ali

    2015-10-01

    The Schiff base complexes, MLCl2 [M = Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)] have been synthesized by the template reaction of respective metal ions with 2-acetylpyrrole and 1,3-diaminopropane in 1:2:1 M ratio. The complexes have been characterized by elemental analyses, ESI - mass, NMR (1H and 13C), IR, XRD, electronic and EPR spectral studies, magnetic susceptibility and molar conductance measurements. These studies show that all the complexes have octahedral arrangement around the metal ions. The molar conductance measurements of all the complexes in DMSO indicate their non-electrolytic nature. The complexes were screened for their antibacterial activity in vitro against Gram-positive (Streptococcus pyogenes) and Gram-negative (Klebsiella pneumoniae) bacteria. Among the metal complexes studied the copper complex [CuLCl2], showed highest antibacterial activity nearly equal to standard drug ciprofloxacin. Other complexes also showed considerable antibacterial activity. The relative order of activity against S. Pyogenes is as Cu(II) > Zn(II) > Co(II) = Fe(II) > Ni(II) and with K. Pneumonia is as Cu(II) > Co(II) > Zn(II) > Fe(II) > Ni(II).

  3. Structural characterization of proteins using residue environments.

    Science.gov (United States)

    Mooney, Sean D; Liang, Mike Hsin-Ping; DeConde, Rob; Altman, Russ B

    2005-12-01

    A primary challenge for structural genomics is the automated functional characterization of protein structures. We have developed a sequence-independent method called S-BLEST (Structure-Based Local Environment Search Tool) for the annotation of previously uncharacterized protein structures. S-BLEST encodes the local environment of an amino acid as a vector of structural property values. It has been applied to all amino acids in a nonredundant database of protein structures to generate a searchable structural resource. Given a query amino acid from an experimentally determined or modeled structure, S-BLEST quickly identifies similar amino acid environments using a K-nearest neighbor search. In addition, the method gives an estimation of the statistical significance of each result. We validated S-BLEST on X-ray crystal structures from the ASTRAL 40 nonredundant dataset. We then applied it to 86 crystallographically determined proteins in the protein data bank (PDB) with unknown function and with no significant sequence neighbors in the PDB. S-BLEST was able to associate 20 proteins with at least one local structural neighbor and identify the amino acid environments that are most similar between those neighbors. Proteins 2005. 2005 Wiley-Liss, Inc.

  4. Synthesis, structural characterization and cell death-inducing effect of novel palladium(II) and platinum(II) saccharinate complexes with 2-(hydroxymethyl)pyridine and 2-(2-hydroxyethyl)pyridine on cancer cells in vitro.

    Science.gov (United States)

    Ari, Ferda; Aztopal, Nazlihan; Icsel, Ceyda; Yilmaz, Veysel T; Guney, Emel; Buyukgungor, Orhan; Ulukaya, Engin

    2013-11-01

    Four palladium(II) and platinum(II) saccharinate (sac) complexes with 2-(hydroxymethyl)pyridine (2-hmpy) and 2-(2-hydroxyethyl)pyridine (2-hepy), namely trans-[Pd(2-hmpy)2(sac)2]·H2O (1), trans-[Pt(2-hmpy)2(sac)2]·3H2O (2), trans-[Pd(2-hepy)2(sac)2] (3) and trans-[Pt(2-hepy)2(sac)2] (4), have been synthesized and characterized by elemental analysis, UV-vis, IR and NMR. Single crystal X-ray analysis reveals that the metal(II) ions in each complex are coordinated by two sac and two 2-hmpy or 2-hepy ligands with a trans arrangement. Anticancer effects of 1-4 were tested against four different cancer cell lines (A549 and PC3 for lung cancer, C6 for glioblastoma, and Hep3B for liver cancer). Cytotoxicity was first screened by the MTT assay and the results were further confirmed by the ATP assay. The mode of cell death was determined by both histological and biochemical methods. Among the metal complexes, complex 2 resulted in relatively stronger anti-growth effect in a dose-dependent manner (3.13-200μM), compared to the others, by inducing apoptosis. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Synthesis and characterization of copper(II) complexes of semicarbazones

    Science.gov (United States)

    Chandra, Usha; Chandra, Sulekh

    1992-08-01

    Copper(II) complexes of the general composition Cu(ligand) 2X 2 (where X=CI -, Br -, NO -3, ClO -4 and 1/2 SO 2-4) and Cu(ligand) (CH 3COO) 2 have been synthesized with methyl n-pentyl ketone and methyl n-hexyl ketone semicarbazones. All the complexes prepared have been characterized by elemental analysis, magnetic moment, molar conductance, IR, electronic and electron spin resonance spectral studies. The complexes Cu(ligand) 2X 2 (X = Cl -, Br -, NO -3) and Cu(ligand) (CH 3COO) 2 may have tetragonal geometry, while the complexes Cu(ligand) 2X 2 (X = ClO -4 and 1/2 SO 2-4) may be assigned a five-coordinated trigonally distorted square pyramidal geometry.

  6. Dual-comb spectroscopy for rapid characterization of complex optical properties of solids.

    Science.gov (United States)

    Asahara, Akifumi; Nishiyama, Akiko; Yoshida, Satoru; Kondo, Ken-Ichi; Nakajima, Yoshiaki; Minoshima, Kaoru

    2016-11-01

    We demonstrate rapid characterization of complex optical properties of solids via dual-comb spectroscopy (DCS) in the near-infrared region. The fine spectral structures in the complex refractive index of an Er:YAG are successfully deduced using the developed system and Fourier analysis. Moreover, simultaneous determination of the refractive index and the thickness is demonstrated for a silicon semiconductor wafer through the use of multireflected echo signals. The results indicate the potential of DCS as a powerful measurement tool for the rapid and full characterization of solid materials.

  7. Characterization of complexities in combustion instability in a lean premixed gas-turbine model combustor.

    Science.gov (United States)

    Gotoda, Hiroshi; Amano, Masahito; Miyano, Takaya; Ikawa, Takuya; Maki, Koshiro; Tachibana, Shigeru

    2012-12-01

    We characterize complexities in combustion instability in a lean premixed gas-turbine model combustor by nonlinear time series analysis to evaluate permutation entropy, fractal dimensions, and short-term predictability. The dynamic behavior in combustion instability near lean blowout exhibits a self-affine structure and is ascribed to fractional Brownian motion. It undergoes chaos by the onset of combustion oscillations with slow amplitude modulation. Our results indicate that nonlinear time series analysis is capable of characterizing complexities in combustion instability close to lean blowout.

  8. Formation, stability and structural characterization of ternary MgUO{sub 2}(CO{sub 3}){sub 3}{sup 2-} and Mg{sub 2}UO{sub 2}(CO{sub 3}){sub 3}(aq) complexes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jun-Yeop; Yun, Jong-Il [KAIST, Daejeon (Korea, Republic of). Dept. of Nuclear and Quantum Engineering; Vespa, Marika; Gaona, Xavier; Dardenne, Kathy; Rothe, Joerg; Rabung, Thomas; Altmaier, Marcus [Karlsruhe Institute of Technology, Karlsruhe (Germany). Inst. for Nuclear Waste Disposal

    2017-06-01

    The formation of ternary Mg-UO{sub 2}-CO{sub 3} complexes under weakly alkaline pH conditions was investigated by time-resolved laser fluorescence spectroscopy (TRLFS) and extended X-ray absorption fine structure (EXAFS) and compared to Ca-UO{sub 2}-CO{sub 3} complexes. The presence of two different Mg-UO{sub 2}-C{sub 3} complexes was identified by means of two distinct fluorescence lifetimes of 17±2 ns and 51±2 ns derived from the multi-exponential decay of the fluorescence signal. Slope analysis in terms of fluorescence intensity coupled with fluorescence intensity factor as a function of log [Mg(II)] was conducted for the identification of the Mg-UO{sub 2}-CO{sub 3} complexes forming. For the first time, the formation of both MgUO{sub 2}(CO{sub 3}){sub 3}{sup 2-} and Mg{sub 2}UO{sub 2}(CO{sub 3}){sub 3}(aq) species was confirmed and the corresponding equilibrium constants were determined as log β {sub 113}=25.8±0.3 and β {sub 213}=27.1±0.6, respectively. Complementarily, fundamental structural information for both Ca-UO{sub 2}-CO{sub 3} and Mg-UO{sub 2}-CO{sub 3} complexes was gained by extended EXAFS revealing very similar structures between these two species, except for the clearly shorter U-Mg distance (3.83 Aa) compared with U-Ca distance (4.15 Aa). These results confirmed the inner-sphere character of the Ca/Mg-UO{sub 2}-CO{sub 3} complexes. The formation constants determined for MgUO{sub 2}(CO{sub 3}){sub 3}{sup 2-} and Mg{sub 2}UO{sub 2}(CO{sub 3}){sub 3}(aq) species indicate that ternary Mg-UO{sub 2}-CO{sub 3} complexes contribute to the relevant uranium species in carbonate saturated solutions under neutral to weakly alkaline pH conditions in the presence of Mg(II) ions, which will induce notable influences on the U(VI) chemical species under seawater conditions.

  9. Complexity of Soils Porous Structure: A Simple Question

    Science.gov (United States)

    Benito, R. M.; Cardenas, J. P.; Santiago, A.; Borondo, F.; Losada, J. C.; Tarquis, A. M.; Grupo de Sistemas Complejos

    2011-12-01

    In the last decades scientist have realized that soil processes are implicated the biggest global challenges facing humanity such as soil aeration, sequestration or emission of greenhouse gasses, volatilization of volatile organic chemicals among other phenomena. Progress in these challenges will depend on being able to understand the integrated behavior of soil as a system, and dealing with the complexity in describing soil in these terms. In this work we focus in one of the critical soil issues: soil structure and pore connectivity. A quantitative and explicit characterization of soil structure is difficult because of the complexity of the pore space. We proposed a model to attempt to capture the complexity of the system in which we interpret porous soils as heterogeneous networks, where pores are represented by nodes and the links representing flows between them. Pore properties such as position and size are described by fixed states in a metric space, while an affinity function is introduced to bias the attachment probabilities of links according to these properties taking in account soil texture. These types of models are named as Heterogeneous Preferential Attachment (HPA). We perform an analytical study of the degree distributions in the soil model and show that under reasonable conditions all the model variants yield a multiscaling behavior in the connectivity degrees, leaving an empirically testable signature of heterogeneity in the topology of pore networks. With the aim to study in more detail topological properties of these networks, for different real soils samples an analysis of the community structure have been applied and studied depending on the values of the parameters of the porous soil model used. The detection of communities of pores, as groups densely connected with only sparser connections between groups, could contribute to understand the mechanisms of the diffusion phenomena in soils. References Cardenas, J. P. Cardenas, A. M. Tarquis, J. C

  10. Physicochemical Characterization of Efavirenz–Cyclodextrin Inclusion Complexes

    OpenAIRE

    Sathigari, Sateeshkumar; Chadha, Gurkishan; Lee, Y-H. Phillip; Wright, Nydeia; Parsons, Daniel L.; Rangari, Vijay K.; Fasina, Oladiran; Babu, R. Jayachandra

    2009-01-01

    Efavirenz (EFV) is an oral antihuman immunodeficiency virus type 1 drug with extremely poor aqueous solubility. Thus, its gastrointestinal absorption is limited by the dissolution rate of the drug. The objective of this study was to characterize the inclusion complexes of EFV with β-cyclodextrin (β-CD), hydroxypropyl β-CD (HPβCD), and randomly methylated β-CD (RMβCD) to improve the solubility and dissolution of EFV. The inclusion complexation of EFV with cyclodextrins in the liquid state was ...

  11. Structure determination of picolinato copper(II)-amine complexes

    Science.gov (United States)

    Mautner, Franz A.; Massoud, Salah S.

    2007-12-01

    Two series of Cu(II)-picolinato complexes of 1:1 and 3:2 Cu(II)-amine/picolinate namely [Cu(L 1)(pic)]ClO 4 and [Cu 3(L 2) 3(pic) 2(H 2O)](ClO 4) 4· xH 2O or [Cu 3(dpt) 3(pic) 2](ClO 4) 4, where pic = picolinate anion, L 1 = dien (diethylenetriamine), Et 2dien ( N, N-diethyldiethylenetriamine), Medpt (3,3'-diamino- N-methyldipropylamine), L 2 = pmedien ( N, N, N', N″, N″-pentamethyl-diethylenetriamine), TPA (tris(2-pyridylmethyl)amine), and dpt = dipropylenetriamine were synthesized and structurally characterized by electronic and IR spectroscopy. Single crystal X-ray diffraction analysis of the complex [Cu(dien)(pic)]ClO 4 ( 1) reveals its monomeric nature whereas for [Cu 3(pmedien) 3(pic) 2(H 2O)](ClO 4) 4·2H 2O ( 4), it was shown that the complex consists of two subunits of the mononuclear [Cu(pmedien)(pic)] + and the dinuclear [Cu 2(pmedien) 2(pic)(H 2O)] 3+ cations with the perchlorate as counter ions and lattice water molecules. In the mononuclear complexes of 1 and 4 the picolinato anions act as N, O-chelating ligands, whereas N, O, O'-picolinato bridges are observed in the dinuclear [Cu 2(pmedien) 2(pic)(H 2O)] 3+ cations of 4. The aqueous visible spectra of the complexes 1- 6 are consistent with five-coordinate Cu(II) species where distorted square pyramidal geometry (SP) was assigned for complexes 2- 5, trigonal bipyramidal geometry (TBP) for 6 and an intermediate geometry between SP and TBP for 1.

  12. The importance of structural complexity in coral reef ecosystems

    Science.gov (United States)

    Graham, N. A. J.; Nash, K. L.

    2013-06-01

    The importance of structural complexity in coral reefs has come to the fore with the global degradation of reef condition; however, the limited scale and replication of many studies have restricted our understanding of the role of complexity in the ecosystem. We qualitatively and quantitatively (where sufficient standardised data were available) assess the literature regarding the role of structural complexity in coral reef ecosystems. A rapidly increasing number of publications have studied the role of complexity in reef ecosystems over the past four decades, with a concomitant increase in the diversity of methods used to quantify structure. Quantitative analyses of existing data indicate a strong negative relationship between structural complexity and algal cover, which may reflect the important role complexity plays in enhancing herbivory by reef fishes. The cover of total live coral and branching coral was positively correlated with structural complexity. These habitat attributes may be creating much of the structure, resulting in a collinear relationship; however, there is also evidence of enhanced coral recovery from disturbances where structural complexity is high. Urchin densities were negatively correlated with structural complexity; a relationship that may be driven by urchins eroding reef structure or by their gregarious behaviour when in open space. There was a strong positive relationship between structural complexity and fish density and biomass, likely mediated through density-dependent competition and refuge from predation. More variable responses were found when assessing individual fish families, with all families examined displaying a positive relationship to structural complexity, but only half of these relationships were significant. Although only corroborated with qualitative data, structural complexity also seems to have a positive effect on two ecosystem services: tourism and shoreline protection. Clearly, structural complexity is an

  13. Preparation, characterization, and stereochemistry of binuclear vanadyl(IV) monomethyl- and dimethyltartrate(4-) complexes and the crystal structure of tetrasodium (. mu. -(+)-dimethyltartrato(4-))-(. mu. -(-)-dimethyltartrato(4-))-bis(oxovanadate(IV)) dodecahydrate

    Energy Technology Data Exchange (ETDEWEB)

    Hahs, S.K.; Ortega, R.B.; Tapscott, R.E.; Campana, C.F.; Morosin, B.

    1982-02-01

    The syntheses and characterizations (by ESR, IR, and electronic spectroscopies) of the sodium salts of the DL and DD (or LL) binuclear complexes of vanadyl(IV) with dimethyltartrate(4-), dmt, and with monomethyltartrate(4-), mmt, are described. Na/sub 4/((VO)/sub 22/((+)-dmt)((-)-dmt)) exists in two crystal forms - a blue dodecahydrate and a pink hexahydrate. An x-ray diffraction study of the former shows that the V-V distance (3.429 (3) A) of the binuclear anion is decreased relative to that of the unsubstituted tartrate(4-), tart, complex, as predicted from earlier ESR studies, and that this decrease is due in part to a dropping of the vanadium atom into the plane of the four coordinating equatorial oxygen atoms. A sixth oxygen atom is weakly coordinated (2.377 (3) A) trans to the vanadyl oxygen atom. A purple tetradecahydrate also obtained with racenic dmt contains a mixture of ((VO)/sub 2/ ((+)-dmt)/sub 2/)/sup 4 -/ and ((VO)/sub 2/((-)-dmt)/sub 2/)/sup 4 -/). The aqueous solution ligand-exchange reaction between the DD and LL complexes of this salt to give the more stable DL isomer is remarkably slow (several hours at room temperature). Stereoselective effects allow the production of mixed-ligand species containing two of the three ligands tart, dmt, and mmt, and potentiometric titrations indicate a decreasing stability of the DL isomer (relative to the DD and LL isomers) as methyl substitution increases.

  14. Complex Convective Thermal Fluxes and Vorticity Structure

    Science.gov (United States)

    Redondo, Jose M.; Tellez, Jackson; Sotillos, Laura; Lopez Gonzalez-Nieto, Pilar; Sanchez, Jesus M.; Furmanek, Petr; Diez, Margarita

    2015-04-01

    Local Diffusion and the topological structure of vorticity and velocity fields is measured in the transition from a homogeneous linearly stratified fluid to a cellular or layered structure by means of convective cooling and/or heating[1,2]. Patterns arise by setting up a convective flow generated by an array of Thermoelectric devices (Peltier/Seebeck cells) these are controlled by thermal PID generating a buoyant heat flux [2]. The experiments described here investigate high Prandtl number mixing using brine and fresh water in order to form density interfaces and low Prandtl number mixing with temperature gradients. The set of dimensionless parameters define conditions of numeric and small scale laboratory modeling of environmental flows. Fields of velocity, density and their gradients were computed and visualized [3,4]. When convective heating and cooling takes place the combination of internal waves and buoyant turbulence is much more complicated if the Rayleigh and Reynolds numbers are high in order to study entrainment and mixing. Using ESS and selfsimilarity structures in the velocity and vorticity fieds and intermittency [3,5] that forms in the non-homogeneous flow is related to mixing and stiring. The evolution of the mixing fronts are compared and the topological characteristics of the merging of plumes and jets in different configurations presenting detailed comparison of the evolution of RM and RT, Jets and Plumes in overall mixing. The relation between structure functions, fractal analysis and spectral analysis can be very useful to determine the evolution of scales. Experimental and numerical results on the advance of a mixing or nonmixing front occurring at a density interface due to body forces [6]and gravitational acceleration are analyzed considering the fractal and spectral structure of the fronts like in removable plate experiments for Rayleigh-Taylor flows. The evolution of the turbulent mixing layer and its complex configuration is studied

  15. AFM Structural Characterization of Drinking Water Biofilm ...

    Science.gov (United States)

    Due to the complexity of mixed culture drinking water biofilm, direct visual observation under in situ conditions has been challenging. In this study, atomic force microscopy (AFM) revealed the three dimensional morphology and arrangement of drinking water relevant biofilm in air and aqueous solution. Operating parameters were optimized to improve imaging of structural details for a mature biofilm in liquid. By using a soft cantilever (0.03 N/m) and slow scan rate (0.5 Hz), biofilm and individual bacterial cell’s structural topography were resolved and continuously imaged in liquid without loss of spatial resolution or sample damage. The developed methodology will allow future in situ investigations to temporally monitor mixed culture drinking water biofilm structural changes during disinfection treatments. Due to the complexity of mixed culture drinking water biofilm, direct visual observation under in situ conditions has been challenging. In this study, atomic force microscopy (AFM) revealed the three dimensional morphology and arrangement of drinking water relevant biofilm in air and aqueous solution. Operating parameters were optimized to improve imaging of structural details for a mature biofilm in liquid. By using a soft cantilever (0.03 N/m) and slow scan rate (0.5 Hz), biofilm and individual bacterial cell’s structural topography were resolved and continuously imaged in liquid without loss of spatial resolution or sample damage. The developed methodo

  16. Synthesis and structural characterization of lithium ...

    Indian Academy of Sciences (India)

    of metal ions spans over s, p, d blocks and recently a few lanthanide complexes were also reported.17–32 .... version 2.1d was used to generate graphics for the X-ray structures. 2.3 General synthetic method for ligands (1 ...... Takolpuckdee P, Tomov A K, White A J P, Williams. D J, Elsegood M R J and Dale S H 2007 Inorg.

  17. Complexity of coherent structures computed from braids of passive particles

    Science.gov (United States)

    Budisic, Marko; Thiffeault, Jean-Luc

    2015-11-01

    Transport in fluids can be characterized by tracking passive particles advected by the fluid flow. When particles are distributed densely, as can be achieved in laboratory, the fluid velocity field can be reconstructed through Particle Tracking Velocimetry, enabling computation of Lyapunov exponents or other numerical analyses. When particles are sparse, as in drifter measurements of oceans, the velocity field cannot be reliably reconstructed. Nevertheless, the amount of entanglement of particle paths over time can be used to estimate the dynamical complexity of the flow by computing the Finite-Time Braiding Exponent (FTBE). The technique is based on braid dynamics and measures the rate at which particle motion stretches topological loops, i.e., the ``rubber bands'' enclosing subsets of particles. Allshouse and Thiffeault showed that minimally-stretching loops correspond to the structures coherent under material transport in flows. We extend their work and couple it to the FTBE calculations in order to characterize the spatial distribution of flow complexity. Analysis is demonstrated on the Hackborn rotor-oscillator model, which exhibits regions of chaotic and regular dynamics, and can be realized both numerically and experimentally. Funded by NSF CMMI-1233935.

  18. The structure and singularities of arc complexes

    DEFF Research Database (Denmark)

    Penner, Robert

    A classical combinatorial fact is that the simplicial complex consisting of disjointly embedded chords in a convex planar polygon is a sphere. For any surface F with non-empty boundary, there is an analogous complex Arc(F) consisting of suitable equivalence classes of arcs in F connecting its bou...

  19. Synthesis and characterization of ruthenium complexes bearing tris ...

    Indian Academy of Sciences (India)

    Administrator

    Tripodal nitrogen donor ligands, in particular, tris(pyrazol-1-yl)borate (Tp), have been employed in organometallic chemistry due to their unique properties. Complexes containing tris(pyrazol-1-yl)methane (TPM) have barely been explored. The isoelectronic as well as similar structural features of TPM and Tp provides an ...

  20. Technetium(III) complexes with the tetradentate umbrella ligand tris (o-mercaptophenyl)phosphinate: X-ray structural characterization of Tc(P(o-C sub 6 H sub 4 S) sub 3 )(CNC sub 3 H sub 7 ) and Tc(P(o-C sub 6 H sub 4 S) sub 3 )(CNC sub 3 H sub 7 ) sub 2

    Energy Technology Data Exchange (ETDEWEB)

    de Vries, N.; Cook, J.; Davison, A. (Massachusetts Inst. of Tech., Cambridge (United States)); Jones, A.G. (Harvard Medical School, Boston, MA (United States))

    1991-06-12

    Tris(o-mercaptophenyl) phosphinate (PS3) binds to Tc(III) as a tetradentate ligand to form the formally 14-electron complex Tc(PS3)(CNMe). An x-ray single-crystal structure determination of the isopropyl isocyanide derivative Tc(PS3)(CN-i-Pr) shows sulfurs bound in the equatorial plane. The crystal data for MF = C{sub 22}H{sub 19}NPS{sub 3}Tc is presented. In the presence of a large excess of isonitrile, these electron-deficient complexes bind a sixth ligand. The six-coordinate complex Tc(PS3)(CN-i-Pr){sub 2}, was also structurally characterized and the crystal data is presented. 8 refs., 2 figs., 4 tabs.

  1. Reliable Multi-Fractal Characterization of Weighted Complex Networks: Algorithms and Implications.

    Science.gov (United States)

    Xue, Yuankun; Bogdan, Paul

    2017-08-08

    Through an elegant geometrical interpretation, the multi-fractal analysis quantifies the spatial and temporal irregularities of the structural and dynamical formation of complex networks. Despite its effectiveness in unweighted networks, the multi-fractal geometry of weighted complex networks, the role of interaction intensity, the influence of the embedding metric spaces and the design of reliable estimation algorithms remain open challenges. To address these challenges, we present a set of reliable multi-fractal estimation algorithms for quantifying the structural complexity and heterogeneity of weighted complex networks. Our methodology uncovers that (i) the weights of complex networks and their underlying metric spaces play a key role in dictating the existence of multi-fractal scaling and (ii) the multi-fractal scaling can be localized in both space and scales. In addition, this multi-fractal characterization framework enables the construction of a scaling-based similarity metric and the identification of community structure of human brain connectome. The detected communities are accurately aligned with the biological brain connectivity patterns. This characterization framework has no constraint on the target network and can thus be leveraged as a basis for both structural and dynamic analysis of networks in a wide spectrum of applications.

  2. Synthesis, structural, spectroscopic and biological studies of Schiff base complexes

    Science.gov (United States)

    Diab, M. A.; El-Sonbati, A. Z.; Shoair, A. F.; Eldesoky, A. M.; El-Far, N. M.

    2017-08-01

    Schiff base ligand 4-((pyridin-2- yl)methyleneamino)-1,2-dihydro-2,3-dimethyl-1-phenylpyrazol-5-one (PDMP) and its complexes were prepared and characterized on the basis of elemental analysis, IR, mass spectra and thermogravimetric analysis. All results confirm that the complexes have 1:1 (M: PMDP) stoichiometric formula [M(PMDP)Cl2H2O ] (M = Cu(II), Co(II), Ni(II) and Mn(II)), [Cd(PMDP)Cl2] and the ligand behaves as a bi/tridentate forming five-membered chelating ring towards the metal ions, bonding through azomethine nitrogen/exocyclic carbonyl oxygen, azomethine pyridine nitrogen and exocyclic carbonyl oxygen. The shift in the band positions of the groups involved in coordination has been utilized to estimate the metal-nitrogen and/or oxygen bond lengths. The complexes of Co(II), Ni(II) and Cu(II) are paramagnetic and the magnetic as well as spectral data suggest octahedral geometry, whereas the Cd(II) complex is tetrahedral. The XRD studies show that both the ligand and its metal complexes (1 and 3) show polycrystalline with crystal structure. Molecular docking was used to predict the binding between PMDP ligand and the receptors. The corrosion inhibition of mild steel in 2 M HCl solution by PDMP was explored utilizing potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and (EFM) electrochemical frequency modulation method. Potentiodynamic polarization demonstrated that PDMP compound is mixed-type inhibitor. EIS spectra exhibit one capacitive loop and confirm the protective ability. The percentage of inhibition efficiency was found to increase with increasing the inhibitor concentration.

  3. A dinuclear dysprosium complex based on schiff base ligand: synthesis, structure and magnetic property

    Science.gov (United States)

    Hu, Peng; Xiao, Fengping; Wu, Lihuan; Chen, Zhisheng

    2017-12-01

    A novel dinuclear dysprosium complex, namely [Dy2 (L) 4 (COO) 2 (CH3OH)2] (1) (L = 2-hydroxy-3-methodxybenzaldehyde-5-bromo oxime), was synthesized, structurally and magnetically characterized. Single-crystal X-ray structural analysis reveals that complex 1 is neutral dinuclear complex, in which two Dy(III) ions with nine-coordinated environment are bridged by two phenoxide groups from two schiff base ligands and four O ions from two molecules of methanoic acid. The magnetic study of complex 1 indicates the slow relaxation of magnetization.

  4. Synthesis, characterization, spectral, thermal analysis and computational studies of thiamine complexes

    Science.gov (United States)

    Masoud, Mamdouh S.; Ghareeb, Doaa A.; Ahmed, Shahenda Sh.

    2017-06-01

    Thiamine metal complexes were synthesized and characterized by elemental analysis, IR, electronic spectra, magnetic susceptibility, ESR spectra of Cu(II) complex and EDX for structural investigation of the complexes to know their geometries and mode of bonding. All the manganese, iron, copper, zinc, tungsten and mercury complexes are with octahedral geometry, while cobalt and nickel complexes are with tetrahedral geometry. The selenium and palladium complexes are with square planner geometry, while vanadium complex with stoichiometry (2:1) is with square pyramidal geometry. The thermal properties of the complexes were examined. The kinetic thermodynamic parameters were estimated from the TGA and DTA curves. Molecular modeling of the ligand and its complexes was performed using PC computer to give extra spot lights on the bonding properties of these compounds. Some theoretical studies were carried out to obtain the charges, bond lengths, bond angles and dihedral angles, energies of highest occupied molecular orbital (EHOMO), energies of lowest unoccupied molecular orbital (ELUMO), the separation energy (ΔE), chemical potential, electronegativity, hardness, softness, ionization potential and electron affinity of the studied ligand and its complexes. Correlation analysis was done to explore the relationships between some different parameters of the studied complexes.

  5. Synthesis and characterization of transition metal complexes derived from some biologically active furoic acid hydrazones

    Directory of Open Access Journals (Sweden)

    P. Venkateswar Rao

    2007-04-01

    Full Text Available Two new physiologically active ligands, N’-2-[(E-1-hydroxy-4-methyl-2-oxo-2H-8-chromenyl ethylidene-2-furan carbohydrazide (HMCFCH and N’-2-[(Z-1-(4-hydroxy-6-methyl-2-oxo-2H-pyranyl ethylidene]-furan carbohydrazide (HMPFCH and their VO(II, Mn(II, Fe(II, Co(II, Ni(II and Cu(II complexes have been prepared. The ligands and the metal complexes have been characterized by elemental analyses, electrical conductance, magnetic susceptibility measurements, UV-Vis, IR, and ESR spectroscopic data. Basing on the above data, Fe(II and Co(II complexes of HMCFCH and HMPFCH have been assigned a dimeric octahedral geometry. VO(II complexes of HMCFCH and HMPFCH have been assigned sulfate bridged dimeric square pyramidal geometry. Mn(II complex of HMCFCH has been assigned a dimeric octahedral geometry, where as Mn(II complex of HMPFCH has been ascribed to monomeric octahedral geometry. Cu(II and Ni(II complexes of HMCFCH have been ascribed to a polymeric structure. Ni(II complex of HMPFCH has been assigned a dimeric square planar geometry. Cu(II complex of HMPFCH has been proposed an octahedral geometry. The ligands and their metal chelates were screened against S. aureus and P. aeruginosa. The ligands and the metal complexes have been found to be active against these microorganisms. The ligands show more activity than the metal complexes.

  6. Synthesis and characterization of calcium beta-diketonate complexes. X-ray crystal and molecular structures of: [{Ca(tmhd)2}2(18-crown-6)], [Ca(dpp)2(thf)2] and [Ca(dpp)2(triglyme)].

    Science.gov (United States)

    El Habra, Naida; Benetollo, Franco; Casarin, Maurizio; Bolzan, Marco; Sartori, Andrea; Rossetto, Gilberto

    2010-09-14

    Reactions of 2,2,6,6-tetramethyl-3,5-heptanedione (Htmhd), 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (Hhfa) or 1,3-diphenyl-1,3-propanedione (Hdpp) with calcium methoxide in hexane or toluene afford the corresponding known oligomeric beta-diketonates: [Ca(3)(tmhd)(6)], [{Ca(hfa)(2)}(n)] and [{Ca(dpp)(2)}(n)]. The complexes react with tetrahydrofuran, 2,5,8,11-tetraoxadodecane (triglyme) or 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) leading to the formation of the new mononuclear [Ca(dpp)(2)(thf)(2)], [Ca(dpp)(2)(triglyme)] and dinuclear [{Ca(dpp)(2)}(2)(18-crown-6)] and [{Ca(tmhd)(2)}(2)(18-crown-6)] adducts. The obtained complexes were characterized by elemental analyses, IR, (1)H and (13)C NMR spectroscopies; moreover, single crystal X-ray diffraction measurements were also carried out for: [{Ca(tmhd)(2)}(2)(18-crown-6)], [Ca(dpp)(2)(thf)(2)] and [Ca(dpp)(2)(triglyme)].

  7. Complex network perspective on structure and function of ...

    Indian Academy of Sciences (India)

    , uncovering complex network structure and function from these networks is becoming one of the most important topics in system biology. This work aims at studying the structure and function of Staphylococcus aureus (S. aureus) metabolic ...

  8. Complex photonic structures for energy efficiency

    Directory of Open Access Journals (Sweden)

    Wiersma D. S.

    2013-06-01

    Full Text Available Photonic structures are playing an increasingly important role in energy efficiency. In particular, they can help to control the flow of light and improve the optical properties of photovoltaic solar cells. We will explain the physics of light transport in such structures with a special focus on disordered materials.

  9. Complex photonic structures for energy efficiency

    Science.gov (United States)

    Burresi, M.; Wiersma, D. S.

    2013-06-01

    Photonic structures are playing an increasingly important role in energy efficiency. In particular, they can help to control the flow of light and improve the optical properties of photovoltaic solar cells. We will explain the physics of light transport in such structures with a special focus on disordered materials.

  10. Structural studies of EF-Tu complexes

    DEFF Research Database (Denmark)

    Johansen, Jesper Sanderhoff

    2011-01-01

    Protein synthesis is a process vital to all living organisms. Protein synthesis occurs on large ribonucleoprotein complexes called ribosomes. Amino acids (aa) are brought to the ribosome as part of a ternary complex consisting of elongation factor EF-Tu, GTP and aminoacyl-tRNA (aa-tRNA). The GTP...... elongation factor, EF-Ts, catalyse the dissociation of GDP from EF-Tu which in turn allows EF-Tu to bind another GTP molecule. The resulting EF-Tu:GTP complex is then cable of forming a ternary complex with a new aa-tRNA which can then associate with the ribosome. During my time as a Ph. D. student I have...... proteins and 22 tRNAs and 2 rRNAs. The mammalian mitochondria have their own specialised translational system for maintaining the synthesis of the 13 proteins. The mammalian mitochondrial protein synthesis resembles the prokaryotic system more than the cytosolic system from eukaryotes. Some of the t...

  11. A new oxovanadium(IV) complex containing an O,N-bidentate Schiff base ligand: Synthesis at ambient temperature, characterization, crystal structure and catalytic performance in selective oxidation of sulfides to sulfones using H2O2 under solvent-free conditions

    Science.gov (United States)

    Menati, Saeid; Rudbari, Hadi Amiri; Khorshidifard, Mahsa; Jalilian, Fariba

    2016-01-01

    A new bidentate ON Schiff base ligand, HL, was synthesized by simple condensation reaction of isopropylamine and salicylaldehyde. Then by reaction of HL and VO(acac)2 in the ratio of 2:1 at ambient temperature, a new oxovanadium(IV) Schiff base complex, VOL2, was synthesized. The Schiff base ligand and its oxovanadium(IV) complex were characterized by elemental analyses, FT-IR, 1H NMR, 13C NMR and UV-visible spectroscopies. The crystal structure of oxovanadium(IV) complex, VOL2, was also determined by single crystal X-ray analysis. The vanadium center in this structure is coordinated to two bidentate Schiff base ligands with the two nitrogen and two phenolate oxygen atoms in equatorial positions and one oxo oxygen in the axial position to complete the distorted trigonal bipyramidal N2O3 coordination sphere. Catalytic performance of the VOL2 complex was studied in the selective oxidation of thioanisole with the green oxidant 35% aqueous H2O2 under solvent-free conditions and under organic solvents (EtOH, CHCl3, CH2Cl2, DMF, CH3CN, EtOAc) as a model. Due to better catalytic performance of the VOL2 complex under solvent-free conditions, this complex used for the oxidation of the different sulfides to the corresponding sulfones under solvent-free conditions. The use of hydrogen peroxide as oxidant and the absence of solvent makes these reactions interesting from environmental and economic points of view.

  12. SCPC: a method to structurally compare protein complexes.

    Science.gov (United States)

    Koike, Ryotaro; Ota, Motonori

    2012-02-01

    Protein-protein interactions play vital functional roles in various biological phenomena. Physical contacts between proteins have been revealed using experimental approaches that have solved the structures of protein complexes at atomic resolution. To examine the huge number of protein complexes available in the Protein Data Bank, an efficient automated method that compares protein complexes is required. We have developed Structural Comparison of Protein Complexes (SCPC), a novel method to structurally compare protein complexes. SCPC compares the spatial arrangements of subunits in a complex with those in another complex using secondary structure elements. Similar substructures are detected in two protein complexes and the similarity is scored. SCPC was applied to dimers, homo-oligomers and haemoglobins. SCPC properly estimated structural similarities between the dimers examined as well as an existing method, MM-align. Conserved substructures were detected in a homo-tetramer and a homo-hexamer composed of homologous proteins. Classification of quaternary structures of haemoglobins using SCPC was consistent with the conventional classification. The results demonstrate that SCPC is a valuable tool to investigate the structures of protein complexes. SCPC is available at http://idp1.force.cs.is.nagoya-u.ac.jp/scpc/. rkoike@is.nagoya-u.ac.jp Supplementary data are available at Bioinformatics online.

  13. Characterization of Hydrogen Complex Formation in III-V Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Michael D

    2006-09-28

    Atomic hydrogen has been found to react with some impurity species in semiconductors. Hydrogenation is a methodology for the introduction of atomic hydrogen into the semiconductor for the express purpose of forming complexes within the material. Efforts to develop hydrogenation as an isolation technique for AlGaAs and Si based devices failed to demonstrate its commercial viability. This was due in large measure to the low activation energies of the formed complexes. Recent studies of dopant passivation in long wavelength (0.98 - 1.55m) materials suggested that for the appropriate choice of dopants much higher activation energies can be obtained. This effort studied the formation of these complexes in InP, This material is extensively used in optoelectronics, i.e., lasers, modulators and detectors. The experimental techniques were general to the extent that the results can be applied to other areas such as sensor technology, photovoltaics and to other material systems. The activation energies for the complexes have been determined and are reported in the scientific literature. The hydrogenation process has been shown by us to have a profound effect on the electronic structure of the materials and was thoroughly investigated. The information obtained will be useful in assessing the long term reliability of device structures fabricated using this phenomenon and in determining new device functionalities.

  14. Identification, isolation, and characterization of cysteinate and thiolactate complexes of bismuth.

    Science.gov (United States)

    Briand, Glen G; Burford, Neil; Eelman, Melanie D; Aumeerally, Nadia; Chen, Luke; Cameron, T Stanley; Robertson, Katherine N

    2004-10-04

    Although bismuth compounds have been used in medicine for over 200 years, chemical characterization of complexes involving biological molecules is minimal and mechanisms of bioactivity are ill-defined. The thiophilic nature of bismuth implicates sulfur centers as likely sites for interaction, and we have exploited this feature to identify, isolate, and characterize complexes of bismuth with thiolate-carboxylate bifunctional ligands including the amino acid l-cysteine. The solid-state structures of potassium dichloro(thiopropionato)bismuth (K[1d]), dimethylaminoethanethiolato(thiopropionato)bismuth (4), and dinitrato(cysteinato)bismuthphenanthroline [5(phen)] are compared with data from electrospray ionization mass spectrometry (ESI-MS). ESI-MS is applied to reactions of BiCl(3) or Bi(NO(3))(3) with mercaptosuccinic, malic, and succinic acids to illustrate the general observation of 1:1 and 1:2 complexes.

  15. Thermodynamic and structural insights into CSL-DNA complexes

    Energy Technology Data Exchange (ETDEWEB)

    Friedmann, David R.; Kovall, Rhett A. (UCIN-MED)

    2010-10-28

    The Notch pathway is an intercellular signaling mechanism that plays important roles in cell fates decisions throughout the developing and adult organism. Extracellular complexation of Notch receptors with ligands ultimately results in changes in gene expression, which is regulated by the nuclear effector of the pathway, CSL (C-promoter binding factor 1 (CBF-1), suppressor of hairless (Su(H)), lin-12 and glp-1 (Lag-1)). CSL is a DNA binding protein that is involved in both repression and activation of transcription from genes that are responsive to Notch signaling. One well-characterized Notch target gene is hairy and enhancer of split-1 (HES-1), which is regulated by a promoter element consisting of two CSL binding sites oriented in a head-to-head arrangement. Although previous studies have identified in vivo and consensus binding sites for CSL, and crystal structures of these complexes have been determined, to date, a quantitative description of the energetics that underlie CSL-DNA binding is unknown. Here, we provide a thermodynamic and structural analysis of the interaction between CSL and the two individual sites that comprise the HES-1 promoter element. Our comprehensive studies that analyze binding as a function of temperature, salt, and pH reveal moderate, but distinct, differences in the affinities of CSL for the two HES-1 binding sites. Similarly, our structural results indicate that overall CSL binds both DNA sites in a similar manner; however, minor changes are observed in both the conformation of CSL and DNA. Taken together, our results provide a quantitative and biophysical basis for understanding how CSL interacts with DNA sites in vivo.

  16. Characterization and conservation of the inner E2 core domain structure of branched-chain alpha-keto acid dehydrogenase complex from bovine liver. Construction of a cDNA encoding the entire transacylase (E2b) precursor.

    Science.gov (United States)

    Griffin, T A; Lau, K S; Chuang, D T

    1988-10-05

    A cDNA clone encoding the entire transacylase (E2b) precursor of the bovine branched-chain alpha-keto acid dehydrogenase complex has been constructed from two overlapping incomplete cDNA clones which were isolated from a lambda ZAP library prepared from bovine liver poly(A)+ RNA. Nucleotide sequencing indicates that this bovine E2b cDNA insert (bE2-11) is 2701 base pairs in length with an open reading frame of 1446 base pairs. The bE2-11 cDNA insert encodes a leader peptide of 61 residues and a mature E2b polypeptide of 421 amino acid residues with a calculated monomeric molecular mass of 46,518 daltons. The molecular mass of the native E2b component isolated from bovine liver is 1,110,000 daltons as determined by sedimentation equilibrium. This value establishes the 24-subunit octahedral model for the quaternary structure of bovine E2b. The amino-terminal sequences of two tryptic fragments (A and B) of the E2b protein have been determined. Fragment A comprises residues 175 to 421 of the E2b protein and is the inner E2 core domain which contains the transacylase active site. Fragment B, produced by further tryptic cleavage of fragment, comprises residues 205 to 421, but does not have transacylase activity. Both fragments A and B confer the highly assembled 24-mer structure. The primary structure of the inner E2 core domain of bovine E2b (fragment A) is very similar to those of three other E2 proteins (human E2p, Escherichia coli E2p, and E. coli E2k). These similarities suggest that these E2 proteins are structurally and evolutionarily related.

  17. Structural characterization of MAPLE deposited lipase biofilm

    Energy Technology Data Exchange (ETDEWEB)

    Aronne, Antonio [Department of Chemical Engineering, Materials and Industrial Production, Università degli Studi di Napoli Federico II, Piazzale V. Tecchio 80, 80125 Napoli (Italy); Ausanio, Giovanni; Bloisi, Francesco [CNR-SPIN and Department of Physics, Università degli Studi di Napoli Federico II, Piazzale V. Tecchio 80, 80125 Napoli (Italy); Calabria, Raffaela [Istituto Motori-CNR, via G. Marconi 8, 80125 Napoli (Italy); Califano, Valeria, E-mail: v.califano@im.cnr.it [Istituto Motori-CNR, via G. Marconi 8, 80125 Napoli (Italy); Fanelli, Esther [Department of Chemical Engineering, Materials and Industrial Production, Università degli Studi di Napoli Federico II, Piazzale V. Tecchio 80, 80125 Napoli (Italy); Massoli, Patrizio [Istituto Motori-CNR, via G. Marconi 8, 80125 Napoli (Italy); Vicari, Luciano R.M. [CNR-SPIN and Department of Physics, Università degli Studi di Napoli Federico II, Piazzale V. Tecchio 80, 80125 Napoli (Italy)

    2014-11-30

    Highlights: • Lipase from Candida Rugosa was deposited by Matrix Assisted Pulsed Laser Evaporation (MAPLE) on KBr pellets, mica and glass substrate. • The deposited film was characterized morphologically and structurally by optical microscopy, SEM and FTIR analysis. • Results of characterization underlined a phenomenon of aggregation taking place. • The aggregation phenomenon was reversible since lipase showed activity in the transesterification reaction between soybean oil and isopropyl alcohol once detached from the substrate. - Abstract: Lipases (triacylglycerol ester hydrolases) are enzymes used in several industrial applications. Enzymes immobilization can be used to address key issues limiting widespread application at industrial level. Immobilization efficiency is related to the ability to preserve the native conformation of the enzyme. MAPLE (Matrix Assisted Pulsed Laser Evaporation) technique, a laser deposition procedure for treating organic/polymeric/biomaterials, was applied for the deposition of lipase enzyme in an ice matrix, using near infrared laser radiation. Microscopy analysis showed that the deposition occurred in micrometric and submicrometric clusters with a wide size distribution. AFM imaging showed that inter-cluster regions are uniformly covered with smaller aggregates of nanometric size. Fourier transform infrared spectroscopy was used for both recognizing the deposited material and analyzing its secondary structure. Results showed that the protein underwent reversible self-association during the deposition process. Actually, preliminary tests of MAPLE deposited lipase used for soybean oil transesterification with isopropyl alcohol followed by gas chromatography–mass spectrometry gave results consistent with undamaged deposition of lipase.

  18. Gelled Complex Fluids: Combining Unique Structures with Mechanical Stability.

    Science.gov (United States)

    Stubenrauch, Cosima; Gießelmann, Frank

    2016-03-01

    Gelled complex fluids are soft materials in which the microstructure of the complex fluid is combined with the mechanical stability of a gel. To obtain a gelled complex fluid one either adds a gelator to a complex fluid or replaces the solvent in a gel by a complex fluid. The most prominent example of a "natural" gelled complex fluid is the cell. There are various strategies by which one can form a gelled complex fluid; one such strategy is orthogonal self-assembly, that is, the independent but simultaneous formation of two coexisting self-assembled structures within one system. The aim of this Review is to describe the structure and potential applications of various man-made gelled complex fluids and to clarify whether or not the respective system is formed by orthogonal self-assembly. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Synthesis and characterization of a novel (glycinato-N,O) yttrium(III) complex (SHORT COMMUNICATION)

    OpenAIRE

    S. R. NIKETIC; I. M. HODZIC

    2001-01-01

    A novel yttrium(III) complex with glycine has been synthesized starting from tris(ethanedioato-O,O)yttrium(III) by the substitution of the acetylacetonato chelate ligands with glycine. The reaction product was purified by ion-exchange chromatography and characterized on the basis of infrared spectroscopy. The structure of the product was tentatively established as tris(glycinato-N,O)yttrium(III) dihydrate.

  20. Synthesis and characterization of a novel (glycinato-N,O yttrium(III complex (SHORT COMMUNICATION

    Directory of Open Access Journals (Sweden)

    S. R. NIKETIC

    2001-05-01

    Full Text Available A novel yttrium(III complex with glycine has been synthesized starting from tris(ethanedioato-O,Oyttrium(III by the substitution of the acetylacetonato chelate ligands with glycine. The reaction product was purified by ion-exchange chromatography and characterized on the basis of infrared spectroscopy. The structure of the product was tentatively established as tris(glycinato-N,Oyttrium(III dihydrate.

  1. Synthesis and Characterization of Rhenium(V) Oxo Complexes Bearing PNP-Pincer Ligands

    NARCIS (Netherlands)

    Korstanje, Ties J.; Lutz, Martin; Jastrzebski, Johann T. B. H.; Klein Gebbink, Bert

    2014-01-01

    The synthesis of a series of pyridine-based PNP-pincer rhenium-oxo complexes, with phenyl (1, 3), tertbutyl (2), or cyclohexyl (4) groups on the phosphorus atoms and either a ReO2X (1, 2) or a ReCl2O (3, 4) core is reported. The structures of these compounds were characterized using H-1, C-13, and

  2. Synthesis, spectral characterization, structural investigation and antimicrobial studies of mononuclear Cu(II), Ni(II), Co(II), Zn(II) and Cd(II) complexes of a new potentially hexadentate N2O4 Schiff base ligand derived from salicylaldehyde

    Science.gov (United States)

    Keypour, Hassan; Shayesteh, Maryam; Rezaeivala, Majid; Chalabian, Firoozeh; Elerman, Yalcin; Buyukgungor, Orhan

    2013-01-01

    A new potentially hexadentate N2O4 Schiff base ligand, H2L derived from condensation reaction of an aromatic diamine and salicylaldehyde, and its metal complexes were characterized by elemental analyses, IR, UV-Vis, EI-MS, 1H and 13C NMR spectra, as well as conductance measurements. It has been originated that the Schiff base ligand with Cu(II), Ni(II), Co(II), Cd(II) and Zn(II) ions form mononuclear complexes on 1:1 (metal:ligand) stoichiometry. The conductivity data confirm the non-electrolytic nature of the complexes. Also the crystal structures of the complexes [ZnL] and [CoL] have also been determined by using X-ray crystallographic technique. The Zn(II) and Co(II) complexes show a tetrahedral configuration. Electronic absorption spectra of the Cu(II) and Ni(II) complexes suggest a square-planar geometry around the central metal ion. The synthesized compounds have antibacterial activity against the three Gram-positive bacteria: Bacillus cereus, Enterococcus faecalis and Listeria monocytogenes and also against the three Gram-negative bacteria: Salmonella paraB, Citrobacter freundii and Enterobacter aerogenes. The results showed that in some cases the antibacterial activity of complexes were more than nalidixic acid and amoxicillin as standards.

  3. Elements for measuring the complexity of 3D structural models: Connectivity and geometry

    Science.gov (United States)

    Pellerin, Jeanne; Caumon, Guillaume; Julio, Charline; Mejia-Herrera, Pablo; Botella, Arnaud

    2015-03-01

    The reliable modeling of three-dimensional complex geological structures can have a major impact on forecasting and managing natural resources and on predicting seismic and geomechanical hazards. However, the qualification of a model as structurally complex is often qualitative and subjective making the comparison of the capabilities and performances of various geomodeling methods or software difficult. In this paper, we consider the notion of structural complexity from a geometrical point of view and argue that it can be characterized using general metrics computed on three-dimensional sealed structural models. We propose global and local measures of the connectivity and of the geometry of the model components and show how they permit to classify nine 3D synthetic structural models. Depending on the complexity elements favored, the classification varies. The models we introduce could be used as benchmark models for geomodeling algorithms.

  4. Higher order structure in a complex plasma

    Science.gov (United States)

    Donkó, Z.; Hartmann, P.; Magyar, P.; Kalman, G. J.; Golden, K. I.

    2017-10-01

    The direct experimental determination of the 3-point static structure function S(3)(k1, k2, k0) of a 2-dimensional dusty plasma liquid is presented. The measurements are complemented by molecular dynamics simulations of the system, using parameters (dust charge, plasma frequency, coupling and screening coefficients), which are derived from the experimentally obtained 2-point static structure function S(2), as well as the dynamic structure function and current-current fluctuation spectra. The experimental results of S(3) are in good agreement with those of the simulations, including the (low wavenumber) domain, where S(3) acquires negative values. The "Convolution Approximation" (giving S(3) in a factorized form of S(2) functions) clearly breaks down in this domain; however, it is found to be a useful aid for explaining the main features of the S(3)(k1, k2, k0) functions, for which (experimental and simulation) maps are presented at selected values of one of its arguments.

  5. Relationships between structural complexity, coral traits, and reef fish assemblages

    Science.gov (United States)

    Darling, Emily S.; Graham, Nicholas A. J.; Januchowski-Hartley, Fraser A.; Nash, Kirsty L.; Pratchett, Morgan S.; Wilson, Shaun K.

    2017-06-01

    With the ongoing loss of coral cover and the associated flattening of reef architecture, understanding the links between coral habitat and reef fishes is of critical importance. Here, we investigate whether considering coral traits and functional diversity provides new insights into the relationship between structural complexity and reef fish communities, and whether coral traits and community composition can predict structural complexity. Across 157 sites in Seychelles, Maldives, the Chagos Archipelago, and Australia's Great Barrier Reef, we find that structural complexity and reef zone are the strongest and most consistent predictors of reef fish abundance, biomass, species richness, and trophic structure. However, coral traits, diversity, and life histories provided additional predictive power for models of reef fish assemblages, and were key drivers of structural complexity. Our findings highlight that reef complexity relies on living corals—with different traits and life histories—continuing to build carbonate skeletons, and that these nuanced relationships between coral assemblages and habitat complexity can affect the structure of reef fish assemblages. Seascape-level estimates of structural complexity are rapid and cost effective with important implications for the structure and function of fish assemblages, and should be incorporated into monitoring programs.

  6. Structures of technetium and rhenium complexes

    OpenAIRE

    Leibnitz, P.; Reck, G.; Pietzsch, H.-J.; H. Spies

    2010-01-01

    Investigations in the 99mTc chemistry are stimulated by the search for new radiopharmaceuticals for nuclear medical applications. To understand the coordination mode of Tc with various complexing agents, macroscopic studies of technetium coordination chemistry are often performed using the low energy ß-emitting radionuclide 99Tc, which has a much longer half life (t1/2 = 2.12 x 105 years) than 99mTc, in the mg level. Investigations of Re coordination chemistry are done in conjunction with Tc ...

  7. Supramolecular Multiblock Copolymers Featuring Complex Secondary Structures.

    Science.gov (United States)

    Elacqua, Elizabeth; Manning, Kylie B; Lye, Diane S; Pomarico, Scott K; Morgia, Federica; Weck, Marcus

    2017-09-06

    This contribution introduces main-chain supramolecular ABC and ABB'A block copolymers sustained by orthogonal metal coordination and hydrogen bonding between telechelic polymers that feature distinct secondary structure motifs. Controlled polymerization techniques in combination with supramolecular assembly are used to engineer heterotelechelic π-sheets that undergo high-fidelity association with both helical and coil-forming synthetic polymers. Our design features multiple advances to achieve our targeted structures, in particular, those emulating sheet-like structural aspects using poly(p-phenylenevinylene)s (PPVs). To engineer heterotelechelic PPVs in a sheet-like design, we engineer an iterative one-pot cross metathesis-ring-opening metathesis polymerization (CM-ROMP) strategy that affords functionalized Grubbs-II initiators that subsequently polymerize a paracyclophanediene. Supramolecular assembly of two heterotelechelic PPVs is used to realize a parallel π-sheet, wherein further orthogonal assembly with helical motifs is possible. We also construct an antiparallel π-sheet, wherein terminal PPV blocks are adjacent to a flexible coil-like poly(norbornene) (PNB). The PNB is designed, through supramolecular chain collapse, to expose benzene and perfluorobenzene motifs that promote a hairpin turn via charge-transfer-aided folding. We demonstrate that targeted helix-(π-sheet)-helix and helix-(π-sheet)-coil assemblies occur without compromising intrinsic helicity, while both parallel and antiparallel β-sheet-like structures are realized. Our main-chain orthogonal assembly approach allows the engineering of multiblock copolymer scaffolds featuring diverse secondary structures via the directional assembly of telechelic building blocks. The targeted assemblies, a mix of sequence-defined helix-sheet-coil and helix-sheet-helix architectures, are Nature-inspired synthetic mimics that expose α/β and α+β protein classes via de novo design and cooperative assembly

  8. Transition Metal(II) Complexes with Cefotaxime-Derived Schiff Base: Synthesis, Characterization, and Antimicrobial Studies

    Science.gov (United States)

    Amzoiu, Emilia; Spînu, Cezar Ionuţ

    2014-01-01

    New [ML2(H2O)2] complexes, where M = Co(II), Ni(II), Cu(II), and Zn(II) while L corresponds to the Schiff base ligand, were synthesized by condensation of cefotaxime with salicylaldehyde in situ in the presence of divalent metal salts in ethanolic medium. The complexes were characterized by elemental analyses, conductance, and magnetic measurements, as well as by IR and UV-Vis spectroscopy. The low values of the molar conductance indicate nonelectrolyte type of complexes. Based on spectral data and magnetic moments, an octahedral geometry may be proposed for Co(II), Ni(II), and Zn(II) complexes while a tetragonal geometry for Cu(II) complex. Molecular structure of the Schiff base ligand and its complexes were studied using programs dedicated to chemical modeling and quantomolecular calculation of chemical properties. All the synthesized complexes were tested for in vitro antibacterial activity against some pathogenic bacterial strains, namely Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus. The MIC values shown by the complexes against these bacterial strains revealed that the metal complexes possess superior antibacterial activity than the Schiff base. PMID:24688454

  9. Preparation and characterization modified chitosan by polyelectrolyte complexation

    Science.gov (United States)

    Zuhannisa, Nugraheni, Prihati Sih; Budhijanto, Wiratni; Kusumastuti, Yuni

    2017-03-01

    The polyelectrolyte complexes (PECs) of chitosan with various polysaccharides such as alginate, carrageenan, Arabic gum, carboxymethylcellulose (CMC), pectin, and glucomannan were prepared and characterized. The complexation was performed by addition of polysaccharide solution as crosslinking agent into chitosan solution (0.01% and 2 %) under magnetic stirring. The size of the obtained modified chitosan was analyzed by Particle Size Analyzer (PSA). The turbidity and pH were measured to observe the stability of the modified chitosan during the storage. The stability of the complexes was investigated at room temperature (37°C) for 3 weeks. The existence of glucomannan and arabic gum resulted PECs when it reacted with the chitosan solution using ratio 1:1. The changed crosslinker resulted a hydrogel after it blended. The obtained PECs could be affected by the ratio between chitosan and polysaccharide and the molecular weight of both polymers. The crosslinker concentration gave a significantly influenced the obtained particle size at the chitosan concentration 0.01 % and 2%.

  10. Structural characterization of bacterioferritin from Blastochloris viridis.

    Directory of Open Access Journals (Sweden)

    Weixiao Y Wahlgren

    Full Text Available Iron storage and elimination of toxic ferrous iron are the responsibility of bacterioferritins in bacterial species. Bacterioferritins are capable of oxidizing iron using molecular oxygen and import iron ions into the large central cavity of the protein, where they are stored in a mineralized form. We isolated, crystallized bacterioferritin from the microaerophilic/anaerobic, purple non-sulfur bacterium Blastochloris viridis and determined its amino acid sequence and X-ray structure. The structure and sequence revealed similarity to other purple bacterial species with substantial differences in the pore regions. Static 3- and 4-fold pores do not allow the passage of iron ions even though structural dynamics may assist the iron gating. On the other hand the B-pore is open to water and larger ions in its native state. In order to study the mechanism of iron import, multiple soaking experiments were performed. Upon Fe(II and urea treatment the ferroxidase site undergoes reorganization as seen in bacterioferritin from Escherichia coli and Pseudomonas aeruginosa. When soaking with Fe(II only, a closely bound small molecular ligand is observed close to Fe(1 and the coordination of Glu94 to Fe(2 changes from bidentate to monodentate. DFT calculations indicate that the bound ligand is most likely a water or a hydroxide molecule representing a product complex. On the other hand the different soaking treatments did not modify the conformation of other pore regions.

  11. Synthesis and characterization of thorium(IV) and uranium(IV) complexes with Schiff bases

    Energy Technology Data Exchange (ETDEWEB)

    Radoske, Thomas; Maerz, Juliane; Kaden, Peter; Patzschke, Michael; Ikeda-Ohno, Atsushi [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Chemistry of the F-Elements

    2017-06-01

    We report herein the synthesis and characterization of several imine complexes of tetravalent thorium (Th(IV)) and uranium (U(IV)). The ligands investigated in this study are a Schiff base type, including the well-known salen ligand (H{sub 2}Le, Fig. 1). The complexation in solution was investigated by NMR measurements indicating paramagnetic effects of unpaired f-electrons of U(IV) on the ligand molecule. We also determined the solid-state molecular structures of the synthesized complexes by single crystal X-ray diffraction. The synthesized complexes show an eight-fold coordination geometry around the actinide center surrounded by two tetradentate ligands with 2N- and 2O-donor atoms.

  12. DEVELOPMENT AND CHARACTERIZATION OF NOVEL COMPLEX HYDRIDESSYNTHESIZED VIA MOLTEN STATE PROCESSING

    Energy Technology Data Exchange (ETDEWEB)

    Zidan, R

    2006-01-09

    This study developed novel hydrides for hydrogen storage through a novel synthesis technique utilizing high hydrogen overpressure at elevated temperatures denoted as Molten State Processing, MSP. The ultimate goal is to produce materials that have high hydrogen capacity, are stable after cycling and possess favorable thermodynamic and kinetic characteristics compatible with onboard hydrogen storage for automotive applications. In order to achieve these goals the MSP Process was developed and used to modify and form new complex hydride compounds with desired characteristics. This synthesis technique holds the potential of fusing different known complex hydrides at elevated temperatures and pressures to form new complexes having different sorption and thermodynamic properties. The new complex hydrides produced by this method were identified through structural determination and thermodynamic characterization in order to achieve a more fundamental understanding of their formation and dissociation mechanisms.

  13. Bipyrimidine ruthenium(II) arene complexes: structure, reactivity and cytotoxicity.

    Science.gov (United States)

    Betanzos-Lara, Soledad; Novakova, Olga; Deeth, Robert J; Pizarro, Ana M; Clarkson, Guy J; Liskova, Barbora; Brabec, Viktor; Sadler, Peter J; Habtemariam, Abraha

    2012-10-01

    The synthesis and characterization of complexes [(η(6)-arene)Ru(N,N')X][PF(6)], where arene is para-cymene (p-cym), biphenyl (bip), ethyl benzoate (etb), hexamethylbenzene (hmb), indane (ind) or 1,2,3,4-tetrahydronaphthalene (thn), N,N' is 2,2'-bipyrimidine (bpm) and X is Cl, Br or I, are reported, including the X-ray crystal structures of [(η(6)-p-cym)Ru(bpm)I][PF(6)], [(η(6)-bip)Ru(bpm)Cl][PF(6)], [(η(6)-bip)Ru(bpm)I][PF(6)] and [(η(6)-etb)Ru(bpm)Cl][PF(6)]. Complexes in which N,N' is 1,10-phenanthroline (phen), 1,10-phenanthroline-5,6-dione or 4,7-diphenyl-1,10-phenanthroline (bathophen) were studied for comparison. The Ru(II) arene complexes undergo ligand-exchange reactions in aqueous solution at 310 K; their half-lives for hydrolysis range from 14 to 715 min. Density functional theory calculations on [(η(6)-p-cym)Ru(bpm)Cl][PF(6)], [(η(6)-p-cym)Ru(bpm)Br][PF(6)], [(η(6)-p-cym)Ru(bpm)I][PF(6)], [(η(6)-bip)Ru(bpm)Cl][PF(6)], [(η(6)-bip)Ru(bpm)Br][PF(6)] and [(η(6)-bip)Ru(bpm)I][PF(6)] suggest that aquation occurs via an associative pathway and that the reaction is thermodynamically favourable when the leaving ligand is I > Br ≈ Cl. pK (a)* values for the aqua adducts of the complexes range from 6.9 to 7.32. A binding preference for 9-ethylguanine (9-EtG) compared with 9-ethyladenine (9-EtA) was observed for [(η(6)-p-cym)Ru(bpm)Cl][PF(6)], [(η(6)-hmb)Ru(bpm)Cl](+), [(η(6)-ind)Ru(bpm)Cl](+), [(η(6)-thn)Ru(bpm)Cl](+), [(η(6)-p-cym)Ru(phen)Cl](+) and [(η(6)-p-cym)Ru(bathophen)Cl](+) in aqueous solution at 310 K. The X-ray crystal structure of the guanine complex [(η(6)-p-cym)Ru(bpm)(9-EtG-N7)][PF(6)](2) shows multiple hydrogen bonding. Density functional theory calculations show that the 9-EtG adducts of all complexes are thermodynamically preferred compared with those of 9-EtA. However, the bmp complexes are inactive towards A2780 human ovarian cancer cells. Calf thymus DNA interactions for [(η(6)-p-cym)Ru(bpm)Cl][PF(6)] and [(η(6)-p

  14. The complex planetary synchronization structure of the solar system

    Science.gov (United States)

    Scafetta, N.

    2014-01-01

    The complex planetary synchronization structure of the solar system, which since Pythagoras of Samos (ca. 570-495 BC) is known as the music of the spheres, is briefly reviewed from the Renaissance up to contemporary research. Copernicus' heliocentric model from 1543 suggested that the planets of our solar system form a kind of mutually ordered and quasi-synchronized system. From 1596 to 1619 Kepler formulated preliminary mathematical relations of approximate commensurabilities among the planets, which were later reformulated in the Titius-Bode rule (1766-1772), which successfully predicted the orbital position of Ceres and Uranus. Following the discovery of the ~ 11 yr sunspot cycle, in 1859 Wolf suggested that the observed solar variability could be approximately synchronized with the orbital movements of Venus, Earth, Jupiter and Saturn. Modern research has further confirmed that (1) the planetary orbital periods can be approximately deduced from a simple system of resonant frequencies; (2) the solar system oscillates with a specific set of gravitational frequencies, and many of them (e.g., within the range between 3 yr and 100 yr) can be approximately constructed as harmonics of a base period of ~ 178.38 yr; and (3) solar and climate records are also characterized by planetary harmonics from the monthly to the millennial timescales. This short review concludes with an emphasis on the contribution of the author's research on the empirical evidences and physical modeling of both solar and climate variability based on astronomical harmonics. The general conclusion is that the solar system works as a resonator characterized by a specific harmonic planetary structure that also synchronizes the Sun's activity and the Earth's climate. The special issue Pattern in solar variability, their planetary origin and terrestrial impacts (Mörner et al., 2013) further develops the ideas about the planetary-solar-terrestrial interaction with the personal contribution of 10

  15. Etude structure-fonction du complexe de remodelage de la chromatine NuRD

    OpenAIRE

    Torchy, Morgan

    2014-01-01

    An integrative structural biology approach has been used to study the structural organization of the NuRD complex.My work focused especially on three subunits of this complex: MBD3, RbAp46 and RbAp48. I set up the preparation of the individual subunits and characterized them by various biophysical methods. We next carried out binding assays with homemade human nucleosomes. For MBD3, optimization of the complex led to crystals diffracting up to 7 Å. In parallel, a preliminary 3-D reconstructio...

  16. Structural Characterization of Chitosan-Clay Nanocomposite

    Science.gov (United States)

    Paluszkiewicz, C.; Weselucha-Birczynska, A.; Stodolak, E.

    2010-08-01

    Novel materials originating from renowable sources mainly consist of biopolymers and their composites or nanocomposites. A typical material belonging to this group is chitosane (CS), which is a cationic natural polysaccharide that can be produced by alkaline N-deacetylation of chitine. Chitosane has a variety of applications in biomedical products, cosmetics, and food processing [1, 2].Organic-inorganic hybrid materials basing on chitosane and nanoclay (montmoryllonite, MMT) were characterized by the vibrational spectrocopy methods (Micro-Raman spectroscopy and FT-Raman spectroscopy) and the thermal analysis methods (TG, DSC). It was shown, that small amount on a nanofiller (MMT, 3 wt.%) used to modify the polymer matrix influences the structure of its polymeric chains.

  17. Community structure of complex networks based on continuous neural network

    Science.gov (United States)

    Dai, Ting-ting; Shan, Chang-ji; Dong, Yan-shou

    2017-09-01

    As a new subject, the research of complex networks has attracted the attention of researchers from different disciplines. Community structure is one of the key structures of complex networks, so it is a very important task to analyze the community structure of complex networks accurately. In this paper, we study the problem of extracting the community structure of complex networks, and propose a continuous neural network (CNN) algorithm. It is proved that for any given initial value, the continuous neural network algorithm converges to the eigenvector of the maximum eigenvalue of the network modularity matrix. Therefore, according to the stability of the evolution of the network symbol will be able to get two community structure.

  18. Reinforcing Visual Grouping Cues to Communicate Complex Informational Structure.

    Science.gov (United States)

    Bae, Juhee; Watson, Benjamin

    2014-12-01

    In his book Multimedia Learning [7], Richard Mayer asserts that viewers learn best from imagery that provides them with cues to help them organize new information into the correct knowledge structures. Designers have long been exploiting the Gestalt laws of visual grouping to deliver viewers those cues using visual hierarchy, often communicating structures much more complex than the simple organizations studied in psychological research. Unfortunately, designers are largely practical in their work, and have not paused to build a complex theory of structural communication. If we are to build a tool to help novices create effective and well structured visuals, we need a better understanding of how to create them. Our work takes a first step toward addressing this lack, studying how five of the many grouping cues (proximity, color similarity, common region, connectivity, and alignment) can be effectively combined to communicate structured text and imagery from real world examples. To measure the effectiveness of this structural communication, we applied a digital version of card sorting, a method widely used in anthropology and cognitive science to extract cognitive structures. We then used tree edit distance to measure the difference between perceived and communicated structures. Our most significant findings are: 1) with careful design, complex structure can be communicated clearly; 2) communicating complex structure is best done with multiple reinforcing grouping cues; 3) common region (use of containers such as boxes) is particularly effective at communicating structure; and 4) alignment is a weak structural communicator.

  19. In situ characterization of structural dynamics in swelling hydrogels.

    Science.gov (United States)

    Guzman-Sepulveda, J R; Deng, J; Fang, J Y; Dogariu, A

    2016-07-06

    Characterizing the structural morphology and the local viscoelastic properties of soft complex systems raises significant challenges. Here we introduce a dynamic light scattering method capable of in situ, continuous monitoring of structural changes in evolving systems such as swelling gels. We show that the inherently non-stationary dynamics of embedded probes can be followed using partially coherent radiation, which effectively isolates only single scattering contributions even during the dramatic changes in the scattering regime. Using a simple and robust experimental setup, we demonstrate the ability to continuously monitor the structural dynamics of chitosan hydrogels formed by the Ag(+) ion-triggered gelation during their long-term swelling process. We demonstrate that both the local viscoelastic properties of the suspending medium and an effective cage size experienced by diffusing probe particles loaded into the hydrogel can be recovered and used to describe the structural dynamics of hydrogels with different levels of cross-linking. This characterization capability is critical for defining and controlling the hydrogel performance in different biomedical applications.

  20. Detailed structural characterization of the grafting of [Ta(=CHtBu)(CH2tBu)3] and [Cp*TaMe4] on silica partially dehydroxylated at 700 C and the activity of the grafted complexes toward alkane metathesis

    Energy Technology Data Exchange (ETDEWEB)

    Le Roux, Erwan; Chabanas, Mathieu; Baudouin, Anne; de Mallmann, Aimery; Coperet, Christophe; Quadrelli, E. Allesandra; Thivolle-Cazat, Jean; Basset, Jean-Marie; Lukens, Wayne; Lesage, Anne; Emsley, Lyndon; Sunley, Glenn J.

    2004-08-30

    The reaction of [Ta({double_bond}CHtBu)(CH{sub 2}tBu){sub 3}] or [Cp*Ta(CH{sub 3}){sub 4}] with a silica partially dehydroxylated at 700 C gives the corresponding monosiloxy surface complexes [({triple_bond}SiO)Ta({double_bond}CHtBu)(CH{sub 2}tBu){sub 2}] and [({triple_bond}SiO)Ta(CH{sub 3}){sub 3}Cp*] by eliminating a {sigma}-bonded ligand as the corresponding alkane (H-CH{sub 2}tBu or H-CH{sub 3}). EXAFS data show that an adjacent siloxane bridge of the surface plays the role of an extra surface ligand, which most likely stabilizes these complexes as in [({triple_bond}SiO)Ta({double_bond}CHtBu)(CH{sub 2}tBu){sub 2}({triple_bond}SiOSi{triple_bond})] (1a') and [({triple_bond}SiO)Ta(CH{sub 3}){sub 3}Cp*({triple_bond}SiOSi{triple_bond})] (2a'). In the case of [({triple_bond}SiO)Ta({double_bond}CHtBu)(CH{sub 2}tBu){sub 2}({triple_bond}SiOSi{triple_bond})], the structure is further stabilized by an additional interaction: a C-H agostic bond as evidenced by the small J coupling constant for the carbenic C-H (H{sub C-H} = 80 Hz), which was measured by J-resolved 2D solid-state NMR spectroscopy. The product selectivity in propane metathesis in the presence of [({triple_bond}SiO)Ta({double_bond}CHtBu)-(CH{sub 2}tBu){sub 2}({triple_bond}SiOSi{triple_bond})] (1a') as a catalyst precursor and the inactivity of the surface complex [({triple_bond}SiO)Ta-(CH{sub 3}){sub 3}Cp*({triple_bond}SiOSi{triple_bond})] (2a') show that the active site is required to be highly electrophilic and probably involves a metallacyclobutane intermediate.

  1. MATERIALS WITH COMPLEX ELECTRONIC/ATOMIC STRUCTURES

    Energy Technology Data Exchange (ETDEWEB)

    D. M. PARKIN; L. CHEN; ET AL

    2000-09-01

    We explored both experimentally and theoretically the behavior of materials at stresses close to their theoretical strength. This involves the preparation of ultra fine scale structures by a variety of fabrication methods. In the past year work has concentrated on wire drawing of in situ composites such as Cu-Ag and Cu-Nb. Materials were also fabricated by melting alloys in glass and drawing them into filaments at high temperatures by a method known as Taylor wire technique. Cu-Ag microwires have been drawn by this technique to produce wires 10 {micro}m in diameter that consist of nanoscale grains of supersaturated solid solution. Organogels formed from novel organic gelators containing cholesterol tethered to squaraine dyes or trans-stilbene derivatives have been studied from several different perspectives. The two types of molecules are active toward several organic liquids, gelling in some cases at w/w percentages as low as 0.1. While relatively robust, acroscopically dry gels are formed in several cases, studies with a variety of probes indicate that much of the solvent may exist in domains that are essentially liquid-like in terms of their microenvironment. The gels have been imaged by atomic force microscopy and conventional and fluorescence microscopy, monitoring both the gelator fluorescence in the case of the stilbene-cholesterol gels and, the fluorescence of solutes dissolved in the solvent. Remarkably, our findings show that several of the gels are composed of similarly appearing fibrous structures visible at the nano-, micro-, and macroscale.

  2. Structure and function of complex brain networks

    Science.gov (United States)

    Sporns, Olaf

    2013-01-01

    An increasing number of theoretical and empirical studies approach the function of the human brain from a network perspective. The analysis of brain networks is made feasible by the development of new imaging acquisition methods as well as new tools from graph theory and dynamical systems. This review surveys some of these methodological advances and summarizes recent findings on the architecture of structural and functional brain networks. Studies of the structural connectome reveal several modules or network communities that are interlinked by hub regions mediating communication processes between modules. Recent network analyses have shown that network hubs form a densely linked collective called a “rich club,” centrally positioned for attracting and dispersing signal traffic. In parallel, recordings of resting and task-evoked neural activity have revealed distinct resting-state networks that contribute to functions in distinct cognitive domains. Network methods are increasingly applied in a clinical context, and their promise for elucidating neural substrates of brain and mental disorders is discussed. PMID:24174898

  3. Two organoantimony (V) coordination complexes modulated by isomers of trifluoromethylbenzoate ligands: Syntheses, crystal structure, photodegradation properties

    Science.gov (United States)

    Zhang, Xiao-Yin; Cui, Lian-sheng; Zhang, Xia; Jin, Fan; Fan, Yu-Hua

    2017-04-01

    Two organoantimony (V) coordination complexes, namely Ph3Sb(2-tmbc) (1) and Ph3Sb(3-tmbc) (2) (2-tmbc = 2-(trifluoromethyl)benzoic carboxyl, 3-tmbc = 3-(trifluoromethyl)benzoic carboxyl) have been synthesized and characterized by IR spectra, elemental analysis, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. Single-crystal X-ray diffraction analysis reveals that complexes 1 and 2 show different architectures by the intermolecular hydrogen bonds (Csbnd H⋯F), complex 1 displays an 1D straight chain structure, while complex 2 shows an 1D zigzag chain structure. The photodegradation properties of complexes 1 and 2 has been investigated in organic dyes (RhB, MV, MB) the results indicated that the two complexes are good candidates for the photocatalytic degradation of three dyes. The tentative photocatalytic degradations mechanism is discussed.

  4. Synthesis, characterization and biological studies of copper(II) complexes with 2-aminobenzimidazole derivatives

    Science.gov (United States)

    Joseph, J.; Suman, A.; Nagashri, K.; Joseyphus, R. Selwin; Balakrishnan, Nisha

    2017-06-01

    Novel series of four copper(II) complexes with 2-aminobenzimidazole derivatives (obtained from the Knoevenagel condensate of acetylacetone (obtained from acetylacetone and halogen substituted benzaldehydes) and 2-aminobenzimidazole) were synthesized. They were structurally characterized using elemental analysis, molar conductance, FAB mass, FT- IR, 1H &13C-NMR, UV-Vis., and EPR techniques. On the basis of analytical and spectral studies, the distorted square planar geometry was assigned for all the complexes. The antibacterial screening of the ligands and their copper complexes indicated that all the complexes showed higher anti microbial activities than the free ligands. Superoxide dismutase and antioxidant activities of the copper complexes have also been performed. In the electrochemical technique, the shift in ΔEp, E1/2 and Ipc values were explored for the interaction of the complexes with CT-DNA. During the electrolysis process, the present ligand system stabilizes unusual oxidation state of copper in the complexes. It is believed that the copper complexes with curcumin analogs may enhance chemotherapeutic behavior.

  5. A dinuclear manganese(II) complex with the [Mn(2)(mu-O(2)CCH(3))(3)](+) core: synthesis, structure, characterization, electroinduced transformation, and catalase-like activity.

    Science.gov (United States)

    Romero, Isabel; Dubois, Lionel; Collomb, Marie-Noëlle; Deronzier, Alain; Latour, Jean-Marc; Pécaut, Jacques

    2002-04-08

    Reactions of Mn(II)(PF(6))(2) and Mn(II)(O(2)CCH(3))(2).4H(2)O with the tridentate facially capping ligand N,N-bis(2-pyridylmethyl)ethylamine (bpea) in ethanol solutions afforded the mononuclear [Mn(II)(bpea)](PF(6))(2) (1) and the new binuclear [Mn(2)(II,II)(mu-O(2)CCH(3))(3)(bpea)(2)](PF(6)) (2) manganese(II) compounds, respectively. Both 1 and 2 were characterized by X-ray crystallographic studies. Complex 1 crystallizes in the monoclinic system, space group P2(1)/n, with a = 11.9288(7) A, b = 22.5424(13) A, c =13.0773(7) A, alpha = 90 degrees, beta = 100.5780(10 degrees ), gamma = 90 degrees, and Z = 4. Crystals of complex 2 are orthorhombic, space group C222(1), with a = 12.5686(16) A, b = 14.4059(16) A, c = 22.515(3) A, alpha = 90 degrees, beta = 90 degrees, gamma = 90 degrees, and Z = 4. The three acetates bridge the two Mn(II) centers in a mu(1,3) syn-syn mode, with a Mn-Mn separation of 3.915 A. A detailed study of the electrochemical behavior of 1 and 2 in CH(3)CN medium has been made. Successive controlled potential oxidations at 0.6 and 0.9 V vs Ag/Ag(+) for a 10 mM solution of 2 allowed the selective and nearly quantitative formation of [Mn(III)(2)(mu-O)(mu-O(2)CCH(3))(2)(bpea)(2)](2+) (3) and [Mn(IV)(2)(mu-O)(2)(mu-O(2)CCH(3))(bpea)(2)](3+) (4), respectively. These results have shown that each substitution of an acetate group by an oxo group is induced by a two-electron oxidation of the corresponding dimanganese complexes. Similar transformations have been obtained if 2 is formed in situ either by direct mixing of Mn(2+) cations, bpea ligand, and CH(3)COO(-) anions with a 1:1:3 stoichiometry or by mixing of 1 and CH(3)COO(-) with a 1:1.5 stoichiometry. Associated electrochemical back-transformations were investigated. 2, 3, and the dimanganese [Mn(III)Mn(IV)(mu-O)(2)(mu-O(2)CCH(3))(bpea)(2)](2+) analogue (5) were also studied for their ability to disproportionate hydrogen peroxide. 2 is far more active compared to 3 and 5. The EPR monitoring of the

  6. Structural Characterization of Bimetallic Nanocrystal Electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Cullen, David A [ORNL

    2016-01-01

    Late transition metal nanocrystals find applications in heterogeneous catalysis such as plasmon-enhanced catalysis and as electrode materials for fuel cells, a zero-emission and sustainable energy technology. Their commercial viability for automotive transportation has steadily increased in recent years, almost exclusively due to the discovery of more efficient bimetallic nanocatalysts for the oxygen reduction reaction (ORR) at the cathode. Despite improvements to catalyst design, achieving high activity while maintaining durability is essential to further enhance their performance for this and other important applications in catalysis. Electronic effects arising from the generation of metal-metal interfaces, from plasmonic metals, and from lattice distortions, can vastly improve sorption properties at catalytic surfaces, while increasing durability.[1] Multimetallic lattice-strained nanoparticles are thus an interesting opportunity for fundamental research.[2,3] A colloidal synthesis approach is demonstrated to produce AuPd alloy and Pd@Au core-shell nanoicosahedra as catalysts for electro-oxidations. The nanoparticles are characterized using aberration-corrected scanning transmission electron microscopy (ac-STEM) and large solid angle energy dispersive X-ray spectroscopy (EDS) on an FEI Talos 4-detector STEM/EDS system. Figure 1 shows bright-field (BF) and high-angle annular dark-field (HAADF) ac-STEM images of the alloy and core-shell nanoicosahedra together with EDS line-scans and elemental maps. These structures are unique in that the presence of twin boundaries, alloying, and core-shell morphology could create highly strained surfaces and interfaces. The shell thickness of the core-shell structures observed in HAADF-STEM images is tuned by adjusting the ratio between metal precursors (Figure 2a-f) to produce shells ranging from a few to several monolayers. Specific activity was measured in ethanol electro-oxidation to examine the effect of shell thickness on

  7. Synthesis, crystal structure and characterization of new biologically ...

    Indian Academy of Sciences (India)

    characterized by FT-IR, electronic, EPR spectroscopic and magnetic methods. ... complexes.15–17. In this paper we report the synthesis, the physico- chemical characterization of two new Cu(II) complexes with N-substituted sulfonamides and we demonstrate .... agent of copper(I), neocuproine (36 μM), along with the.

  8. Iron complexes of chiral phenol-oxazoline ligands: Structural studies and oxidation catalysis

    NARCIS (Netherlands)

    Godbole, M.D.; Prat Puig, M.; Tanase, S.; Kooijman, H.|info:eu-repo/dai/nl/091208610; Spek, A.L.|info:eu-repo/dai/nl/156517566; Bouwman, E.

    2007-01-01

    Iron complexes of two ligands, HphoxCOOH and HphoxiPr, have been synthesized and characterized by crystal structure analyses. The complexes (HNEt3)2[Fe(phoxCOO)2](ClO4) and [Fe(phoxiPr)3] are reported. Reactions of the ligands rac-HphoxCOOH and rac- HphoxiPr with iron(II) or iron(III) perchlorate

  9. Mesoscopic hydrothermodynamics of complex-structured materials.

    Science.gov (United States)

    Vasconcellos, Áurea R; Silva, A A P; Luzzi, Roberto; Casas-Vázquez, J; Jou, David

    2013-10-01

    Some experimental results in the study of disordered systems, polymeric fluids, solutions of micelles and surfactants, ionic-glass conductors, and others show a hydrodynamic behavior labeled "anomalous" with properties described by some kind of fractional power laws in place of the standard ones. This is a consequence of the fractal-like structure that is present in these systems of which we do not have a detailed description, thus impairing the application of the conventional ensemble formalism of statistical mechanics. In order to obtain a physical picture of the phenomenon for making predictions which may help with technological and industrial decisions, one may resort to different styles (so-called nonconventional) in statistical mechanics. In that way can be introduced a theory for handling such impaired situations, a nonconventional mesoscopic hydrothermodynamics (MHT). We illustrate the question presenting an application in a contracted description of such nonconventional MHT, consisting in the use of the Renyi approach to derive a set of coupled nonstandard evolution equations, one for the density, a nonconventional Maxwell-Cattaneo equation, which in a limiting case goes over a non-Fickian diffusion equation, and other for the velocity in fluids under forced flow. For illustration the theory is applied to the study of the hydrodynamic motion in several soft-matter systems under several conditions such as streaming flow appearing in electrophoretic techniques and flow generated by harmonic forces arising in optical traps. The equivalence with Lévy processes is discussed and comparison with experiment is done.

  10. Synthesis, characterization and catalytic activity of nanosized Ni complexed aminoclay

    Science.gov (United States)

    Ranchani, A. Amala Jeya; Parthasarathy, V.; Devi, A. Anitha; Meenarathi, B.; Anbarasan, R.

    2017-11-01

    A novel Ni complexed aminoclay (AC) catalyst was prepared by complexation method followed by reduction reaction. Various analytical techniques such as FTIR spectroscopy, UV-visible spectroscopy, DSC, TGA, SEM, HRTEM, EDX, XPS and WCA measurement are used to characterize the synthesized material. The AC-Ni catalyst system exhibited improved thermal stability and fiber-like morphology. The XPS results declared the formation of Ni nanoparticles. Thus, synthesized catalyst was tested towards the Schiff base formation reaction between various bio-medical polymers and aniline under air atmosphere at 85 °C for 24 h. The catalytic activity of the catalyst was studied by varying the % weight loading of the AC-Ni system towards the Schiff base formation. The Schiff base formation was quantitatively calculated by the 1H-NMR spectroscopy. While increasing the % weight loading of the AC-Ni catalyst, the % yield of Schiff base was also increased. The k app and Ti values were determined for the reduction of indole and α-terpineol in the presence of AC-Ni catalyst system. The experimental results were compared with the literature report.

  11. Synthesis and molecular structure of manganese complexes with ...

    Indian Academy of Sciences (India)

    Administrator

    Synthesis and molecular structure of manganese complexes with hindered N3 ligand. UDAI P SINGHa, R SINGHa, S HIKICHIb and Y MORO-OKAb ... O–N distances in this complex are shorter (011-N82, 2·76(1) Å) than the range of distances expected for a hydrogen bond between the peroxide and the imidazole proton.

  12. Synthesis, structure, redox and spectra of green iridium complexes ...

    Indian Academy of Sciences (India)

    TECS

    3. *For correspondence. Synthesis, structure, redox and spectra of green iridium complexes of tridentate azo-aromatic ligands. MANASHI PANDA,a CHAYAN DAS,a CHEN-HSIUNG HUNGb and. SREEBRATA ... Mn(II)7 and Fe(II)8 but also produces stable anionic ..... the EPR of the oxidized complexes were not suc- cessful ...

  13. Cryo-electron Microscopy Analysis of Structurally Heterogeneous Macromolecular Complexes.

    Science.gov (United States)

    Jonić, Slavica

    2016-01-01

    Cryo-electron microscopy (cryo-EM) has for a long time been a technique of choice for determining structure of large and flexible macromolecular complexes that were difficult to study by other experimental techniques such as X-ray crystallography or nuclear magnetic resonance. However, a fast development of instruments and software for cryo-EM in the last decade has allowed that a large range of complexes can be studied by cryo-EM, and that their structures can be obtained at near-atomic resolution, including the structures of small complexes (e.g., membrane proteins) whose size was earlier an obstacle to cryo-EM. Image analysis to identify multiple coexisting structures in the same specimen (multiconformation reconstruction) is now routinely done both to solve structures at near-atomic resolution and to study conformational dynamics. Methods for multiconformation reconstruction and latest examples of their applications are the focus of this review.

  14. Structural Characterization of Myotoxic Ecarpholin S From Echis carinatus Venom

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, X.; Tan, T; Valiyaveettil, S; Go, M; Kini, R; Velazquez-Campoy, A; Sivaraman, J

    2008-01-01

    Phospholipase A2 (PLA2), a common toxic component of snake venom, has been implicated in various pharmacological effects. Ecarpholin S, isolated from the venom of the snake Echis carinatus sochureki, is a phospholipase A2 (PLA2) belonging to the Ser49-PLA2 subgroup. It has been characterized as having low enzymatic but potent myotoxic activities. The crystal structures of native ecarpholin S and its complexes with lauric acid, and its inhibitor suramin, were elucidated. This is the first report of the structure of a member of the Ser49-PLA2 subgroup. We also examined interactions of ecarpholin S with phosphatidylglycerol and lauric acid, using surface plasmon resonance, and of suramin with isothermal titration calorimetry. Most Ca2+-dependent PLA2 enzymes have Asp in position 49, which plays a crucial role in Ca2+ binding. The three-dimensional structure of ecarpholin S reveals a unique conformation of the Ca2+-binding loop that is not favorable for Ca2+ coordination. Furthermore, the endogenously bound fatty acid (lauric acid) in the hydrophobic channel may also interrupt the catalytic cycle. These two observations may account for the low enzymatic activity of ecarpholin S, despite full retention of the catalytic machinery. These observations may also be applicable to other non-Asp49-PLA2 enzymes. The interaction of suramin in its complex with ecarpholin S is quite different from that reported for the Lys49-PLA2/suramin complex, where the interfacial recognition face (i-face), C-terminal region, and N-terminal region of ecarpholin S play important roles. This study provides significant structural and functional insights into the myotoxic activity of ecarpholin S and, in general, of non-Asp49-PLA2 enzymes.

  15. Structural characterization of the interaction of human lactoferrin with calmodulin.

    Directory of Open Access Journals (Sweden)

    Jessica L Gifford

    Full Text Available Lactoferrin (Lf is an 80 kDa, iron (Fe(3+-binding immunoregulatory glycoprotein secreted into most exocrine fluids, found in high concentrations in colostrum and milk, and released from neutrophil secondary granules at sites of infection and inflammation. In a number of cell types, Lf is internalized through receptor-mediated endocytosis and targeted to the nucleus where it has been demonstrated to act as a transcriptional trans-activator. Here we characterize human Lf's interaction with calmodulin (CaM, a ubiquitous, 17 kDa regulatory calcium (Ca(2+-binding protein localized in the cytoplasm and nucleus of activated cells. Due to the size of this intermolecular complex (∼100 kDa, TROSY-based NMR techniques were employed to structurally characterize Ca(2+-CaM when bound to intact apo-Lf. Both CaM's backbone amides and the ε-methyl group of key methionine residues were used as probes in chemical shift perturbation and cross-saturation experiments to define the binding interface of apo-Lf on Ca(2+-CaM. Unlike the collapsed conformation through which Ca(2+-CaM binds the CaM-binding domains of its classical targets, Ca(2+-CaM assumes an extended structure when bound to apo-Lf. Apo-Lf appears to interact predominantly with the C-terminal lobe of Ca(2+-CaM, enabling the N-terminal lobe to potentially bind another target. Our use of intact apo-Lf has made possible the identification of a secondary interaction interface, removed from CaM's primary binding domain. Secondary interfaces play a key role in the target's response to CaM binding, highlighting the importance of studying intact complexes. This solution-based approach can be applied to study other regulatory calcium-binding EF-hand proteins in intact intermolecular complexes.

  16. Characterization of the effects of lignin and lignin complex particles as filler on a polystyrene film

    Energy Technology Data Exchange (ETDEWEB)

    El-Zawawy, Waleed K., E-mail: wkzawawy@yahoo.com [Cellulose and Paper Department, National Research Center, El-Tahrir St., Giza (Egypt); Ibrahim, Maha M. [Cellulose and Paper Department, National Research Center, El-Tahrir St., Giza (Egypt); Belgacem, Mohamed Naceur; Dufresne, Alain [Grenoble Institute of Technology (INP) - The International School of Paper, Print Media and Biomaterials (PAGORA), BP 65, 38402 Saint Martin d' Heres cedex, Grenoble (France)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer We have studied the use of Co(II) to form a complex with the lignin. We use first vanillin as the lignin model and we observed a change in color for the produced complex depending on the light wavelength. The use of other transition metals does not give the same observation. Black-Right-Pointing-Pointer The use of the transition metal with the lignin precipitated from the black liquor after pulping of agricultural residues, gave a fluorescent color under fluorescent microscope. Black-Right-Pointing-Pointer We applied the resulted lignin complex to prepare polymer film that can be used as special polymer packaging which can be color changed under different wavelengths. - Abstract: The work in this research outlines the use of lignin precipitated from lignocellulosic substrate as fillers after modified with transition metal cations, Fe(III), Ni(II) and Co(II), in the production of a polystyrene based composite for polymer packaging applications. Virgin polystyrene was compared with lignin and lignin complex filled composites with loading of 5% by weight prepared using twin screw extrusion. The lignin complexes were first characterized by the UV spectra to identify the new absorption bands occurred due to the complex formation. Moreover, lignin model, namely vanillin, was used to notify the geometric structure of the resulting complexes applying the GC mass spectra. Scanning electron microscopy was used to indicate the change in the morphological structure of the filler particles. On the other hand, the mechanical and thermal analysis for the resulting polymer composites was studied and it was noticed that the type of lignin or lignin complex plays a roll in the results. The inclusion of the Co(II)-lignin complex was observed to increase the tensile strength of the resulting polymer composite and a decrease of the glass transition temperature. Furthermore, light wave lengths and UV fluorescent microscope were used to identify

  17. Structural characterization of SiC nanoparticles

    Science.gov (United States)

    Sun, Baoxing; Xie, Ruobing; Yu, Cun; Li, Cheng; Xu, Hongjie

    2017-10-01

    The structure and size of SiC nanoparticles were studied by different characterization methods including small angle X-ray scattering (SAXS), transmission electron microscope (TEM), and X-ray diffraction (XRD). The results showed that particle size distributions determined respectively from SAXS and TEM are comparable and follow the log-normal function. The size distribution of the particles is between 10 to 100 nm with most of them being in the range of 20–50 nm. The average particle size is around 42 nm. XRD identifies the phase of the SiC nanoparticles and suggests the average size of the single crystalline domain to be around 21 nm. The combined results from XRD and SAXS suggest the existence of many polycrystals, which is confirmed by the HRTEM observation of particles with twins and stacking faults. The material synthesis methods leading to various particle sizes are also discussed. Project supported by the National Natural Science Foundation of China (No. 11505273) and the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDA02000000).

  18. Structure of immune stimulating complex matrices and immune stimulating complexes in suspension determined by small-angle X-ray scattering

    DEFF Research Database (Denmark)

    Pedersen, J.S.; Oliveira, C.L.P.; Hübschmann, Henriette Baun

    2012-01-01

    Immune stimulating complex (ISCOM) particles consisting of a mixture of Quil-A, cholesterol, and phospholipids were structurally characterized by small-angle x-ray scattering (SAXS). The ISCOM particles are perforated vesicles of very well-defined structures. We developed and implemented a novel ...

  19. Synthesis, crystal structures, spectroscopic characterization and in ...

    Indian Academy of Sciences (India)

    ... mode of carboxylate bridged dinuclear complex, in which, the coordination geometry around Cu(1) is square pyramid and distorted square planar around Cu(2). The target complexes were screened for in vitro antidiabetic activity. Both the complexes showed good inhibitory activity for α-amylase and α-glucosidase.

  20. Synthesis, XRD and spectroscopic characterization of pharmacologically active Cu(II) and Zn(II) complexes

    Science.gov (United States)

    Gull, Parveez; Hashmi, Athar Adil

    2017-07-01

    The present contribution accounts for the synthesis and structural elucidation of a newly synthesised copper and zinc containing schiff base compounds obtained by the condensation of 1, 2-diphenylethane-1, 2-dione and dinitrophenyl hydrazine as main ligand and benzene-1,2-diamine as co-ligand respectively. The synthesised compounds were characterized by several techniques, including elemental analysis, molar conductance and electronic, FT-IR, XRD, mass and 1H NMR spectral studies. The analytical and molar conductance values indicated that the complexes have square planar and tetrahedral geometry respectively. X-ray powder diffraction illustrates that they are crystalline in nature. The copper and zinc complexes were screened for their antimicrobial potential against some bacterial and fungi strains and the assay indicate that these complexes are good antimicrobial agents against these tested pathogens.

  1. Structural and evolutionary versatility in protein complexes with uneven stoichiometry.

    Science.gov (United States)

    Marsh, Joseph A; Rees, Holly A; Ahnert, Sebastian E; Teichmann, Sarah A

    2015-03-16

    Proteins assemble into complexes with diverse quaternary structures. Although most heteromeric complexes of known structure have even stoichiometry, a significant minority have uneven stoichiometry--that is, differing numbers of each subunit type. To adopt this uneven stoichiometry, sequence-identical subunits must be asymmetric with respect to each other, forming different interactions within the complex. Here we first investigate the occurrence of uneven stoichiometry, demonstrating that it is common in vitro and is likely to be common in vivo. Next, we elucidate the structural determinants of uneven stoichiometry, identifying six different mechanisms by which it can be achieved. Finally, we study the frequency of uneven stoichiometry across evolution, observing a significant enrichment in bacteria compared with eukaryotes. We show that this arises due to a general increased tendency for bacterial proteins to self-assemble and form homomeric interactions, even within the context of a heteromeric complex.

  2. Structuring and assessing large and complex decision problems using MCDA

    DEFF Research Database (Denmark)

    Barfod, Michael Bruhn

    This paper presents an approach for the structuring and assessing of large and complex decision problems using multi-criteria decision analysis (MCDA). The MCDA problem is structured in a decision tree and assessed using the REMBRANDT technique featuring a procedure for limiting the number of pair...

  3. Structure of Coordination Complexes: The Synergy between NMR ...

    African Journals Online (AJOL)

    Illustrative examples of how NMR spectroscopy and computational chemistry data can be used in synergy to gain information on structure, coordination mode, bonding, symmetry and isomeric distribution of transition metal complexes, is presented. Isomer distribution and the most stable structures in a series of ...

  4. Cu(II AND Zn(II COMPLEX COMPOUNDS WITH BIGUANIDES AROMATIC DERIVATIVES. SYNTHESIS, CHARACTERIZATION, BIOLOGICAL ACTIVITY

    Directory of Open Access Journals (Sweden)

    Ticuţa Negreanu-Pîrjol

    2011-05-01

    Full Text Available In this paper we report the synthesis, physical-chemical characterization and antimicrobial activity of some new complex compounds of hetero-aromatic biguanides ligands, chlorhexidine base (CHX and chlorhexidine diacetate (CHXac2 with metallic ions Cu(II and Zn(II, in different molar ratio. The synthesized complexes were characterized by elemental chemical analysis and differential thermal analysis. The stereochemistry of the metallic ions was determined by infrared spectra, UV-Vis, EPR spectroscopy and magnetic susceptibility in the aim to establish the complexes structures. The biological activity of the new complex compounds was identified in solid technique by measuring minimum inhibition diameter of bacterial and fungal culture, against three standard pathogen strains, Escherichia coli ATCC 25922, Staphilococcus aureus ATCC 25923 and Candida albicans ATCC 10231. The results show an increased specific antimicrobial activity for the complexes chlorhexidine:Cu(II 1:1 and 1:2 compared with the one of the Zn(II complexes.

  5. Oxoglaucine-lanthanide complexes: synthesis, crystal structure and cytotoxicity.

    Science.gov (United States)

    Liu, Yan-Cheng; Chen, Zhen-Feng; Shi, Yan-Fang; Huang, Ke-Bin; Geng, Bo; Liang, Hong

    2014-01-01

    To evaluate the in vitro cytotoxicity of oxoglaucine (OG) complexes: [Sm(OG)2(NO3)3]•H2O (1), [Eu(OG)2(NO3)3]•1.5CH3OH (2) and [Er(OG)2(NO3)3]•H2O (3) through comparison to oxoglaucine and lanthanide salts. The reactions of OG with corresponding lanthanide salts gave rise to complexes 1-3. The crystal structures of complexes 1-3 were determined by single-crystal X-ray diffraction analysis. The in vitro cytotoxicity of oxoglaucine and complexes 1-3 against five human cancer cell lines were evaluated by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium Bromide (MTT) method. Complexes 1-3 have similar mononuclear structures. The 50% inhibitory concentration (IC50) of complex 1 against SGC7901 cells was 32.1 μM; that of complex 2 against MCF-7 cells was 3.2 μM; those of complex 3 on HeLa and MCF-7 cells were 8.3 and 1.4 μM, respectively. The three OG-lanthanide complexes exhibited significantly enhanced cytotoxicity vs. OG and corresponding lanthanide salts.

  6. Unequivocal determination of complex molecular structures using anisotropic NMR measurements.

    Science.gov (United States)

    Liu, Yizhou; Saurí, Josep; Mevers, Emily; Peczuh, Mark W; Hiemstra, Henk; Clardy, Jon; Martin, Gary E; Williamson, R Thomas

    2017-04-07

    Assignment of complex molecular structures from nuclear magnetic resonance (NMR) data can be prone to interpretational mistakes. Residual dipolar couplings and residual chemical shift anisotropy provide a spatial view of the relative orientations between bonds and chemical shielding tensors, respectively, regardless of separation. Consequently, these data constitute a reliable reporter of global structural validity. Anisotropic NMR parameters can be used to evaluate investigators' structure proposals or structures generated by computer-assisted structure elucidation. Application of the method to several complex structure assignment problems shows promising results that signal a potential paradigm shift from conventional NMR data interpretation, which may be of particular utility for compounds not amenable to x-ray crystallography. Copyright © 2017, American Association for the Advancement of Science.

  7. A new entropy based method for computing software structural complexity

    CERN Document Server

    Roca, J L

    2002-01-01

    In this paper a new methodology for the evaluation of software structural complexity is described. It is based on the entropy evaluation of the random uniform response function associated with the so called software characteristic function SCF. The behavior of the SCF with the different software structures and their relationship with the number of inherent errors is investigated. It is also investigated how the entropy concept can be used to evaluate the complexity of a software structure considering the SCF as a canonical representation of the graph associated with the control flow diagram. The functions, parameters and algorithms that allow to carry out this evaluation are also introduced. After this analytic phase follows the experimental phase, verifying the consistency of the proposed metric and their boundary conditions. The conclusion is that the degree of software structural complexity can be measured as the entropy of the random uniform response function of the SCF. That entropy is in direct relation...

  8. Room Temperature Solid State Synthesis, Characterization, and Application of a Zinc Complex with Pyromellitic Acid

    Directory of Open Access Journals (Sweden)

    Rong-Gui Yang

    2018-01-01

    Full Text Available The complex [Zn2(btca(H2O4] was synthesized with 1,2,4,5-benzenetetracarboxylic acid (H4btca and zinc acetate as materials via a room-temperature solid state reaction. The composition and structure of the complex were characterized by elemental analyses (EA, Fourier transform infrared spectroscopy (FTIR, X-ray powder diffraction (XRD, and thermogravimetric (TG analysis. The index results of X-ray powder diffraction data showed that the crystal structure of the complex belonged to monoclinic system with cell parameters a = 9.882 Å, b = 21.311 Å, c = 15.746 Å, and β = 100.69°. In order to expand the application of the complex, the nanometer zinc oxide was prepared by using the complex as a precursor, and the effect of the thermal decomposition temperature on the preparation of the nanometer zinc oxide was studied. The results showed that the grain size of zinc oxide gradually grew with the increase of the pyrolysis temperature, the obtained nanometer zinc oxide was spherical, and the diameter of the particles was about 25 nm.

  9. Synthesis, characterization, and biological evaluation of Schiff base-platinum(II) complexes.

    Science.gov (United States)

    Shiju, C; Arish, D; Bhuvanesh, N; Kumaresan, S

    2015-06-15

    The platinum complexes of Schiff base ligands derived from 4-aminoantipyrine and a few substituted aldehydes were synthesized and characterized by elemental analysis, mass, (1)H NMR, IR, electronic spectra, molar conductance, and powder XRD. The structure of one of the ligands L5 was confirmed by a single crystal XRD analysis. The Schiff base ligand crystallized in the triclinic, space group P-1 with a=7.032(2)Ǻ, b=9.479(3)Ǻ, c=12.425(4)Ǻ, α=101.636(3)°, β=99.633(3)°, γ=94.040(3)°, V=795.0(4)Ǻ(3), Z=2, F(000)=352, Dc=1.405 mg/m(3), μ=0.099 mm(-1), R=0.0378, and wR=0.0967. The spectral results show that the Schiff base ligand acts as a bidentate donor coordinating through the azomethine nitrogen and the carbonyl oxygen atoms. The geometrical structures of these complexes are found to be square planar. Antimicrobial studies indicate that these complexes exhibit better activity than the ligand. The anticancer activities of the complexes have also been studied towards human cervical cancer cell line (HeLa), Colon Cancer Cells (HCT116) and Epidermoid Carcinoma Cells (A431) and it was found that the [Pt(L3)Cl2] complex is more active. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Characterization of Forest Structure and an Assessment of Litter ...

    African Journals Online (AJOL)

    Characterization of Forest Structure and an Assessment of Litter Production, Accumulation and Litter-asscociated Invertebrates in Two Naturally Occuring Rhizophora mucronata Stands in Mauritius (Indian Ocean)

  11. Efficient Characterization of Parametric Uncertainty of Complex (Biochemical Networks.

    Directory of Open Access Journals (Sweden)

    Claudia Schillings

    2015-08-01

    Full Text Available Parametric uncertainty is a particularly challenging and relevant aspect of systems analysis in domains such as systems biology where, both for inference and for assessing prediction uncertainties, it is essential to characterize the system behavior globally in the parameter space. However, current methods based on local approximations or on Monte-Carlo sampling cope only insufficiently with high-dimensional parameter spaces associated with complex network models. Here, we propose an alternative deterministic methodology that relies on sparse polynomial approximations. We propose a deterministic computational interpolation scheme which identifies most significant expansion coefficients adaptively. We present its performance in kinetic model equations from computational systems biology with several hundred parameters and state variables, leading to numerical approximations of the parametric solution on the entire parameter space. The scheme is based on adaptive Smolyak interpolation of the parametric solution at judiciously and adaptively chosen points in parameter space. As Monte-Carlo sampling, it is "non-intrusive" and well-suited for massively parallel implementation, but affords higher convergence rates. This opens up new avenues for large-scale dynamic network analysis by enabling scaling for many applications, including parameter estimation, uncertainty quantification, and systems design.

  12. Characterization of Responsive Hydrogel Nanoparticles upon Polyelectrolyte Complexation

    Directory of Open Access Journals (Sweden)

    Su-Kyoung Lee

    2017-02-01

    Full Text Available Characterization of responsive hydrogels and their interaction with other molecules have significantly expanded our understanding of the functional materials. We here report on the response of poly(N-isopropylacrylamide-co-acrylic acid (pNIPAm-co-AAc nanogels to the addition of the poly(allylamine hydrochloride (PAH in aqueous dispersions. We find that the hydrodynamic radius and stability of nanogels are dependent on the PAH/nanogel stoichiometry. If the nanogel solution is titrated with very small aliquots of PAH, the nanogels decrease in radius until the equivalence point, followed by aggregation at suprastoichiometric PAH additions. Conversely, when titrated with large aliquots, the nanogel charge switches rapidly from anionic to cationic, and no aggregation is observed. This behavior correlates well with electrophoretic mobility measurements, which shows the nanogel charge transitioning from negative to positive upon PAH addition. The volume phase transition temperature (VPTT of the nanogels is also measured to discover the effect of polyelectrolyte complexation on the deswelling thermodynamics. These data show that charge neutralization upon PAH addition decreases the VPTT of the nanogel at pH 6.5. However, if an excess amount of PAH is added to the nanogel solution, the VPTT shifts back to higher temperatures due to the formation of a net positive charge in the nanogel network.

  13. Structural characterization of copolymer embedded magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Nedelcu, G.G., E-mail: ggnedelcu@yahoo.com [Faculty of Physics, University “Alexandru Ioan Cuza”, Carol I Bulevard, Nr.11, 700506 Iasi (Romania); Nastro, A.; Filippelli, L. [Department of Chemistry and Chemical Technology, University of Calabria, Via P. Bucci, 87036 Arcavacata di Rende, Cosenza (Italy); Cazacu, M.; Iacob, M. [Institute of Macromolecular Chemistry “Petru Poni”, Aleea Grigore Ghica Voda, nr. 41A, 700487 Iasi (Romania); Rossi, C. Oliviero [Department of Chemistry and Chemical Technology, University of Calabria, Via P. Bucci, 87036 Arcavacata di Rende, Cosenza (Italy); Popa, A.; Toloman, D. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Str., 400293 Cluj-Napoca 5 (Romania); Dobromir, M.; Iacomi, F. [Faculty of Physics, University “Alexandru Ioan Cuza”, Carol I Bulevard, Nr.11, 700506 Iasi (Romania)

    2015-10-15

    Highlights: • The emulsion polymerization method was used to synthesize three samples of poly(methyl methacrylate-co-acrylic acid) coated magnetite obtained before through co-precipitation technique. • Poly(methyl methacrylate-co-acrylic acid) coated magnetite nanoparticles were prepared having spherical shape and dimensions between 13 and 16 nm without agglomerations. • Fourier transform infrared spectra have found that the magnetite was pure and spectral characteristics of PMMA-co-AAc were present. • The electron spin resonance spectra revealed that interactions between nanoparticles are very weak due to the fact that the nanoparticles have been individually embedded in polymer. • The resonance field values as function of temperature demonstrate that the presence of polymer has not modified essentially its magnetic properties, except that at temperatures below 140 K there was a change due to decreasing of the magnetic anisotropy. - Abstract: Small magnetic nanoparticles (Fe{sub 3}O{sub 4}) were synthesized by co-precipitation and coated by emulsion polymerization with poly(methyl methacrylate-co-acrylic acid) (PMMA-co-AAc) to create surface functional groups that can attach drug molecules and other biomolecules. The coated and uncoated magnetite nanoparticles were stored for two years in normal closed ships and than characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, vibrating sample magnetometry, and electron paramagnetic resonance spectroscopy. The solid phase transformation of magnetite to maghemite, as well as an increase in particle size were evidenced for the uncoated nanoparticles. The coated nanoparticles preserved their magnetite structure and magnetic properties. The influences of monomers and surfactant layers on interactions between the magnetic nanoparticles evidenced that the thickness of the polymer has a significant effect on magnetic properties.

  14. THE NATURE OF CYCLIC STRUCTURE OF THE ICE COMPLEX, EAST SIBERIA

    Directory of Open Access Journals (Sweden)

    Vyacheslav Konishchev

    2013-01-01

    Full Text Available The features of cyclic structure in the Karga-Sartan Ice Complex (IC deposits in Northern Yakutia have been studied for the coastal lowlands. We have analyzed cycles of different genesis (cryolithological, structural, lithological, and soil-vegetation and duration. Climate fluctuation was the major factor of cyclic structure in the IC deposits. Cyclic structure in the IC deposits develops in certain facial-genetic conditions characterized by cryogenic weathering and subsequent re-deposition of eroded soils in river valleys and alas depressions

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

    Energy Technology Data Exchange (ETDEWEB)

    Simagina, L. V., E-mail: lsimagina@gmail.com; Gaynutdinov, R. V.; Stepina, N. D.; Sorokina, K. L. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Morozova, O. V.; Shumakovich, G. P.; Yaropolov, A. I., E-mail: yaropolov@inbi.ras.ru [Russian Academy of Sciences, Bach Institute of Biochemistry (Russian Federation); Tolstikhina, A. L. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2010-07-15

    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.

  16. Synthesis, spectroscopic characterization, DFT optimization and biological activities of Schiff bases and their metal (II) complexes

    Science.gov (United States)

    Rauf, Abdur; Shah, Afzal; Munawar, Khurram Shahzad; Khan, Abdul Aziz; Abbasi, Rashda; Yameen, Muhammad Arfat; Khan, Asad Muhammad; Khan, Abdur Rahman; Qureshi, Irfan Zia; Kraatz, Heinz-Bernhard; Zia-ur-Rehman

    2017-10-01

    A Novel Schiff base, 3-(((4-chlorophenyl)imino)methyl)benzene-1,2-diol (HL1) was successfully synthesized along with a structurally similar Schiff base 3-(((4-bromophenyl)imino)methyl)benzene-1,2-diol (HL2). Both the Schiff bases were used to synthesize their zinc (II) and cobalt (II) complexes. These compounds were characterized by FTIR, 1H NMR, 13C NMR and elemental analysis. Metal complexes were confirmed by TGA. Crystals of Schiff bases were also characterized by X-ray analysis and experimental parameters were found in line with the theoretical parameters. Quantum mechanical approach was also used to fine useful structural parameters and to ensure the geometry of metal complexes. The photometric behaviors of all the synthesized compounds were investigated in a wide pH range using BR buffers. The appearance of isosbestic points indicated the existence of Schiff bases in more than one isomeric form. Moreover, these compounds were screened for enzyme inhibition; antibacterial, cytotoxic and in vivo antidiabetic activities and compounds were found active against one or other activity. Results indicate that ZnL22 is a good inhibitor of alkaline phosphatase enzyme and possess highest potential against diabetes, blood cholesterol level and cancer cells. This effort just provides preliminary data for some biological properties. Further investigations are required to precisely determine mechanistic pathways of their use towards drug development.

  17. Metal complexes of N'-(2-hydroxy-5-phenyldiazenyl benzylideneisonicotinohydrazide: Synthesis, spectroscopic characterization and antimicrobial activity

    Directory of Open Access Journals (Sweden)

    El-Tabl Abdou S.

    2013-01-01

    Full Text Available A new series of Cu(II, Ni(II, Co(II, Mn(II, Zn(II, Cd(II, Hg(II , VO(II, UO2(II , Fe(III and Ru(III complexes of N'-(2-hydroxy-5- phenyldiazenylbenzylideneisonicotinohydrazide(H2L have been synthesized and characterized by elemental,1H-NMR, IR, UV-Vis., ESR, magnetic, thermogravimetric analyses(TG and conductivity measurements. The spectral data show that, the ligand behaves as a neutral bidentate, (2, (4, (5, (6 and (14, monobasic bidentate, (3, (7, (8, (9 and (10, monobasic tridentate (11 and (16 or dibasic tridentate (12, (13 and (15 bonded to metal ions via the carbonyl oxygen atom in ketonic or enolic form, azomethine nitrogen atom and/or deprotonated phenolic hydroxyl oxygen. The ESR spectrum of solid vanadyl(II, complex (2 shows axially anisotropic spectrum with eight lines in the low field region and g?>g||, A||>>A?relationship, which is characteristics of distorted octahedral structure with dxy ground state. However, copper(II complexes (4, (5 and (6 and manganese(II complex (10 show an isotropic type while the copper(II complexes (3 and (7show an axial symmetry type with g||>g?>ge indicating a covalent bond character. The antibacterial and antifungal activities of the ligand and its metal complexes show mild activity compared with standard drugs (Tetracycline for bacteria and amphotricene B for fungi.

  18. Studies on solid phase synthesis,characterization and fluorescent property of the new rare earth complexes

    Directory of Open Access Journals (Sweden)

    Jianwei SHI

    2015-04-01

    Full Text Available Rare earth-β-diketone ligand complex luminescent material has stable chemical properties and excellent luminous property. Using europium oxide and (γ-NTA as raw materials, novel rare earth-β-dione complexes are synthesized by solid state coordination chemistry. The synthesis temperature and milling time are discussed for optimization. Experimental results show that the suitable reaction situation is at 50 ℃ and 20 h for solid-phase synthesis. The compositions and structures of the complexes are characterized by means of elemental analysis, UV-Vis and FTIR methods, and the phase stability of the complex is determined by using TG-DTA technique. It is proved that preparation of waterless binary rare earth complexes by the solid phase reaction method results in a higher product yield. The fluorescence spectra show that between Eu (Ⅲ and γ-NTA, there exists efficient energy transfer, and the rare earth complexes synthesis is an excellent red bright light-emitting material with excellent UV excited luminescence properties.

  19. Isolation and structural characterization of chondroitin sulfate from bony fishes.

    Science.gov (United States)

    Maccari, Francesca; Galeotti, Fabio; Volpi, Nicola

    2015-09-20

    Chondroitin sulfate (CS) was purified from the bones of common fishes, monkfish, cod, spiny dogfish, salmon and tuna, and characterized in an effort to find alternative sources and new peculiar structures of this complex biomacromolecule utilized in the pharmaceutical and nutraceutical industry. Quantitative analyses yielded a CS content ranging from 0.011% for cod up to 0.34% for monkfish. The disaccharide pattern showed the presence of nonsulfated disaccharide, monosulfated species ΔDi6s and ΔDi4s, and disulfated disaccharides in different percentages. The disulfated species ΔDi2,6dis was present in all CS extracts in a range of 1.3-10.5%. The presence of these disulfated disaccharides may be a useful marker for the marine origin of CS. The newly identified sources would certainly enable the production of CS with unique disaccharide composition and properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Synthesis and Characterization of Rare Earth Corrole-Phthalocyanine Heteroleptic Triple-Decker Complexes.

    Science.gov (United States)

    Lu, Guifen; Li, Jing; Yan, Sen; Zhu, Weihua; Ou, Zhongping; Kadish, Karl M

    2015-06-15

    We recently reported the first example of a europium triple-decker tetrapyrrole with mixed corrole and phthalocyanine macrocycles and have now extended the synthetic method to prepare a series of rare earth corrole-phthalocyanine heteroleptic triple-decker complexes, which are characterized by spectroscopic and electrochemical methods. The examined complexes are represented as M2[Pc(OC4H9)8]2[Cor(ClPh)3], where Pc = phthalocyanine, Cor = corrole, and M is Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), or Tb(III). The Y(III) derivative with OC4H9 Pc substituents was obtained in too low a yield to characterize, but for the purpose of comparison, Y2[Pc(OC5H11)8]2[Cor(ClPh)3] was synthesized and characterized in a similar manner. The molecular structure of Eu2[Pc(OC4H9)8]2[Cor(ClPh)3] was determined by single-crystal X-ray diffraction and showed the corrole to be the central macrocycle of the triple-decker unit with a phthalocyanine on each end. Each triple-decker complex undergoes up to eight reversible or quasireversible one-electron oxidations and reductions with E1/2 values being linearly related to the ionic radius of the central ions. The energy (E) of the main Q-band is also linearly related to the radius of the metal. Comparisons are made between the physicochemical properties of the newly synthesized mixed corrole-phthalocyanine complexes and previously characterized double- and triple-decker derivatives with phthalocyanine and/or porphyrin macrocycles.

  1. Revealing and exploiting hierarchical material structure through complex atomic networks

    Science.gov (United States)

    Ahnert, Sebastian E.; Grant, William P.; Pickard, Chris J.

    2017-08-01

    One of the great challenges of modern science is to faithfully model, and understand, matter at a wide range of scales. Starting with atoms, the vastness of the space of possible configurations poses a formidable challenge to any simulation of complex atomic and molecular systems. We introduce a computational method to reduce the complexity of atomic configuration space by systematically recognising hierarchical levels of atomic structure, and identifying the individual components. Given a list of atomic coordinates, a network is generated based on the distances between the atoms. Using the technique of modularity optimisation, the network is decomposed into modules. This procedure can be performed at different resolution levels, leading to a decomposition of the system at different scales, from which hierarchical structure can be identified. By considering the amount of information required to represent a given modular decomposition we can furthermore find the most succinct descriptions of a given atomic ensemble. Our straightforward, automatic and general approach is applied to complex crystal structures. We show that modular decomposition of these structures considerably simplifies configuration space, which in turn can be used in discovery of novel crystal structures, and opens up a pathway towards accelerated molecular dynamics of complex atomic ensembles. The power of this approach is demonstrated by the identification of a possible allotrope of boron containing 56 atoms in the primitive unit cell, which we uncover using an accelerated structure search, based on a modular decomposition of a known dense phase of boron, γ-B28.

  2. Information structure and reference tracking in complex sentences

    CERN Document Server

    Gijn, Rik van; Matic, Dejan

    2014-01-01

    This paper discusses argument marking and reference tracking in Mekens complex clauses and their correlation to information structure. The distribution of pronominal arguments in Mekens simple clauses follows an absolutive pattern with main verbs. Complex clauses maintain the morphological absolutive argument marking, but show a nominative pattern with respect to argument reference tracking, since transitive and intransitive subjects function as syntactic pivots. The language extends the use of argument-marking verb morphology to control the reference of discourse participants across clauses.

  3. The Structure of DNA within Cationic Lipid/DNA Complexes

    OpenAIRE

    Braun, Chad S.; Jas, Gouri S.; Choosakoonkriang, Sirirat; Koe, Gary S.; Smith, Janet G.; Middaugh, C. Russell

    2003-01-01

    The structure of DNA within CLDCs used for gene delivery is controversial. Previous studies using CD have been interpreted to indicate that the DNA is converted from normal B to C form in complexes. This investigation reexamines this interpretation using CD of model complexes, FTIR as well as Raman spectroscopy and molecular dynamics simulations to address this issue. CD spectra of supercoiled plasmid DNA undergo a significant loss of rotational strength in the signal near 275 nm upon interac...

  4. Synthesis, structural characterization, superoxide dismutase and antimicrobial activities studies of copper (II) complexes with 2-(E)-(2-(2-aminoethylamino) methyl)-4-bromophenol and (19E, 27E)-N1, N2-bis (phenyl (pyridine-2-yl)-methylene)-ethane-1, 2-diamine as ligands

    Science.gov (United States)

    Choudhary, Mukesh; Patel, R. N.; Rawat, S. P.

    2014-07-01

    Three new copper (II) complexes, [Cu(L)(H2O)]ClO4 (1), [Cu(L1)(ClO4)]+ (2) and [Cu(L1)]2+ (3), where HL = 2-(E)-(2-(2-aminoethylamino)methyl)-4-bromophenol, L1 =(19E, 27E)-N1,N2-bis(phenyl(pyridine-2-yl)-methylene)-ethane-1, 2-diamine, have been synthesized and characterized by using various physic-chemical and spectroscopic methods. The solid-state structures of 1 and 2 were determined by single crystal X-ray crystallography. Infrared spectra, ligand field spectra and magnetic susceptibility measurements agree with the observed crystal structures. The molecular structure of copper complexes showed that the ligands occupies the basal plane of square pyramidal geometry with the H2O of 1 or the ClO4 of 2 occupying the remaining apical position. Complexes 1 and 2 crystallize in the monoclinic system of the space group P21/c, a = 10.5948(6)Å, b = 19.6164(11)Å, c = 8.6517(5)Å, α = 90°, β = 108.213(2)°, γ = 90° and Z = 4 for 1, a = 9.5019(3)Å, b = 11.3 801(3)Å, c = 25.3168(14)Å, α = 90°, β = 100.583(4)°, γ = 90°, and Z = 4 for 2. The synthesized Schiff base (HL/L1) was behaves as tetradentate ON3/N4 ligands with donor groups suitable placed for forming 2 or 3 five membered chelate rings. Copper (II) complexes display X-band EPR spectra in 100% DMSO at 77 K giving g|| > g⊥ > 2.0023 indicating dx2-y2 ground state. The half-wave potential values for Cu (II)/Cu (I) redox couple obtained in the reaction of the copper (II) complexes with molecular oxygen and superoxide radical (O2-) electronegated in DMSO are in agreement with the SOD-like activity of the copper (II) complexes. In vitro antimicrobial activities of the complexes against the two bacteria (Escherichia coli, Salmonella typhi) and the two fungi (Penicillium, Aspergillus sp.) have been investigated comparing with the Schiff base ligands.

  5. Structural, magnetic and luminescent properties of lanthanide complexes with N-salicylideneglycine.

    Science.gov (United States)

    Vančo, Ján; Trávníček, Zdeněk; Kozák, Ondřej; Boča, Roman

    2015-04-28

    A series of anionic heavy lanthanide complexes, involving the N-salicylideneglycinato(2-) Schiff base ligand (salgly) and having the general formula K[Ln(salgly)₂(H₂O)₂]∙H₂O (1-6), where Ln stands for Gd, Tb, Dy, Ho, Er and Tm, was prepared using the one-pot template synthesis. The complexes were thoroughly characterized by elemental and Thermogravimetric/Differential Thermal Analyses (TG/DTA), Fourier Transform Infrared Spectroscopy (FT-IR), and photoluminescence spectroscopies, electrospray-ionization mass spectrometry, and their magnetic properties were studied by temperature-dependent dc magnetic measurements using the superconducting quantum interference device (SQUID). The X-ray structure of the terbium(III) complex (2), representing the unique structure between the lanthanide complexes of N-salicylideneamino acids, was determined. The results of spectral and structural studies revealed the isostructural nature of the prepared complexes, in which the lanthanide ion is octacoordinated by two O,N,O-donor salgly ligands and two aqua ligands. The analysis of magnetic data confirmed that the complexes behave as paramagnets obeying the Curie law. The results of photoluminescence spectral studies of the complexes showed the different origin in their luminescent properties between the solid state and solution. An antenna effect of the Schiff base ligand was observed in a powder form of the complex only, while it acts as a fluorophore in a solution.

  6. Structural, Magnetic and Luminescent Properties of Lanthanide Complexes with N-Salicylideneglycine

    Directory of Open Access Journals (Sweden)

    Ján Vančo

    2015-04-01

    Full Text Available A series of anionic heavy lanthanide complexes, involving the N-salicylideneglycinato(2- Schiff base ligand (salgly and having the general formula K[Ln(salgly2(H2O2]∙H2O (1–6, where Ln stands for Gd, Tb, Dy, Ho, Er and Tm, was prepared using the one-pot template synthesis. The complexes were thoroughly characterized by elemental and Thermogravimetric/Differential Thermal Analyses (TG/DTA, Fourier Transform Infrared Spectroscopy (FT-IR, and photoluminescence spectroscopies, electrospray-ionization mass spectrometry, and their magnetic properties were studied by temperature-dependent dc magnetic measurements using the superconducting quantum interference device (SQUID. The X-ray structure of the terbium(III complex (2, representing the unique structure between the lanthanide complexes of N-salicylideneamino acids, was determined. The results of spectral and structural studies revealed the isostructural nature of the prepared complexes, in which the lanthanide ion is octacoordinated by two O,N,O-donor salgly ligands and two aqua ligands. The analysis of magnetic data confirmed that the complexes behave as paramagnets obeying the Curie law. The results of photoluminescence spectral studies of the complexes showed the different origin in their luminescent properties between the solid state and solution. An antenna effect of the Schiff base ligand was observed in a powder form of the complex only, while it acts as a fluorophore in a solution.

  7. Copper-based metal coordination complexes with Voriconazole ligand: Syntheses, structures and antimicrobial properties

    Science.gov (United States)

    Zhao, Yan-Ming; Tang, Gui-Mei; Wang, Yong-Tao; Cui, Yue-Zhi; Ng, Seik Weng

    2018-03-01

    Three new chiral metal coordination complexes, namely, [Cu(FZ)2(CH3COO)2(H2O)]·2H2O (1), [Cu(FZ)2(NO3)2] (2), and [Cu2(FZ)2 (H2O)8](SO4)2·4H2O (3) [FZ = (2R,3S)-2-(2,4-difluorophenyl)-3-(5-fluoro-4-pyrimidiny)-1-(1H-1,2,4-triazol-1-yl)-2-butanol) (Voriconazole)] have been obtained by the reaction of Cu(II) salts and the free ligand FZ at room temperature. Complexes 1-3 were structurally characterized by X-ray single-crystal diffraction, IR, UV-vis, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). Complex 1 crystallizes in the chiral space group C2, which exhibits a mono-nuclear structure. Both complexes 2 and 3 display a one-dimensional (1D) tape structure, which crystallize in chiral space group P21212 and P212121, respectively. Among these complexes, there exist a variety of hydrogen bonds and stacking interactions, through which a three-dimensional supramolecular architecture will be generated. Compared with the standard (Voriconazole), these Cu-based complexes show the more potent inhibiting efficiency against the species of Candida and Aspergillus. Moreover, among these complexes, complex 1 shows the most excellent efficiency.

  8. Towards the Structural Characterization of Intrinsically Disordered Proteins by SAXS and MD Simulation

    Science.gov (United States)

    Oroguchi, Tomotaka; Ikeguchi, Mitsunori; Sato, Mamoru

    2011-01-01

    Dynamical structures of intrinsically disordered proteins (IDPs) and multi-domain proteins that include large ID regions between the domains are unable to be determined by such conventional methods as X-ray crystallography and electron microscopy. Small-angle X-ray scattering (SAXS) is suitable to determine low-resolution structures of proteins and protein complexes in solution, but the structural data on protein dynamics are averaged over the structural ensemble in protein solution. To overcome this problem, we have developed a novel method, named MD-SAXS, of the combined use of SAXS and molecular dynamics (MD) simulation to analyze protein dynamics in solution of multi-subunit protein complexes and multi-domain proteins toward the structural characterization of IDPs. Here we show validity of the method through the structural characterization of restriction Endonuclease EcoO109I.

  9. Factors influencing efficient structure of fuel and energy complex

    Science.gov (United States)

    Sidorova, N. G.; Novikova, S. A.

    2017-10-01

    The development of the Russian fuel-energy complex is a priority for the national economic policy, and the Far East is a link between Russia and the Asia-Pacific region. Large-scale engineering of numerous resources of the Far East will force industrial development, increase living standard and strengthen Russia’s position in the global energy market. So, revealing the factors which influence rational structure of the fuel-energy complex is very urgent nowadays. With the use of depth analysis of development tendencies of the complex and its problems the authors show ways of its efficiency improvement.

  10. Structural insight into the UNC-45–myosin complex

    DEFF Research Database (Denmark)

    Fratev, Filip; Jonsdottir, Svava Osk; Pajeva, Ilza

    2013-01-01

    is mainly stabilized by electrostatic interactions. Remarkably, the contact surface area is similar to that of the myosinactin complex. A significant interspecies difference in the myosin binding epitope is observed. Our results reveal the structural basis of MYH7 exons 15–16 hypertrophic cardiomyopathy......The UNC-45 chaperone protein interacts with and affects the folding, stability, and the ATPase activity of myosins. It plays a critical role in the cardiomyopathy development and in the breast cancer tumor growth. Here we propose the first structural model of the UNC-45–myosin complex using various...

  11. Brackets, sigma models and integrability of generalized complex structures

    Energy Technology Data Exchange (ETDEWEB)

    Guttenberg, Sebastian [Service de Physique Theorique, CEA/Saclay, 91191 Gif-sur-Yvette Cedex (France); Institut fuer Theoretische Physik, Technische Universitaet Wien, 1040 Vienna (Austria)

    2007-06-15

    It is shown how derived brackets naturally arise in sigma-models via Poisson- or antibracket, generalizing a recent observation by Alekseev and Strobl. On the way to a precise formulation of this relation, an explicit coordinate expression for the derived bracket is obtained. The generalized Nijenhuis tensor of generalized complex geometry is shown to coincide up to a de-Rham closed term with the derived bracket of the structure with itself and a new coordinate expression for this tensor is presented. The insight is applied to two known two-dimensional sigma models in a background with generalized complex structure.

  12. Structure, complexity and cooperation in parallel external chat interactions

    DEFF Research Database (Denmark)

    Grønning, Anette

    2012-01-01

    This article examines structure, complexity and cooperation in external chat interactions at the workplace in which one of the participants is taking part in multiple parallel conversations. The investigation is based on an analysis of nine chat interactions in a work-related context, with partic......This article examines structure, complexity and cooperation in external chat interactions at the workplace in which one of the participants is taking part in multiple parallel conversations. The investigation is based on an analysis of nine chat interactions in a work-related context...

  13. Characterization of the superior olivary complex of Canis lupus domesticus.

    Science.gov (United States)

    Fech, Tatiana; Calderón-Garcidueñas, Lilian; Kulesza, Randy J

    2017-08-01

    The superior olivary complex (SOC) is a collection of brainstem auditory nuclei which play essential roles in the localization of sound sources, temporal coding of vocalizations and descending modulation of the cochlea. Notwithstanding, the SOC nuclei vary considerably between species in accordance with the auditory needs of the animal. The canine SOC was subjected to anatomical and physiological examination nearly 50 years ago and was then virtually forgotten. Herein, we aimed to characterize the nuclei of the canine SOC using quantitative morphometrics, estimation of neuronal number, histochemistry for perineuronal nets and immunofluorescence for the calcium binding proteins calbindin and calretinin. We found the principal nuclei to be extremely well developed: the lateral superior olive (LSO) contained over 20,000 neurons and the medial superior olive (MSO) contained over 15,000 neurons. In nearly all non-chiropterian terrestrial mammals, the MSO exists as a thin, vertical column of neurons. The canine MSO was folded into a U-shaped contour and had associated with the ventromedial tip a small, round collection of neurons we termed the tail nucleus of the MSO. Further, we found evidence within the LSO, MSO and medial nucleus of the trapezoid body (MNTB) for significant morphological variations along the mediolateral or rostrocaudal axes. Finally, the majority of MNTB neurons were calbindin-immunopositive and associated with calretinin-immunopositive calyceal terminals. Together, these observations suggest the canine SOC complies with the basic plan of the mammalian SOC but possesses a number of unique anatomical features. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Characterization of Catalytically Active Octahedral Metal Halide Cluster Complexes

    Directory of Open Access Journals (Sweden)

    Satoshi Kamiguchi

    2014-04-01

    Full Text Available Halide clusters have not been used as catalysts. Hexanuclear molecular halide clusters of niobium, tantalum, molybdenum, and tungsten possessing an octahedral metal framework are chosen as catalyst precursors. The prepared clusters have no metal–metal multiple bonds or coordinatively unsaturated sites and therefore required activation. In a hydrogen or helium stream, the clusters are treated at increasingly higher temperatures. Above 150–250 °C, catalytically active sites develop, and the cluster framework is retained up to 350–450 °C. One of the active sites is a Brønsted acid resulting from a hydroxo ligand that is produced by the elimination of hydrogen halide from the halogen and aqua ligands. The other active site is a coordinatively unsaturated metal, which can be isoelectronic with the platinum group metals by taking two or more electrons from the halogen ligands. In the case of the rhenium chloride cluster Re3Cl9, the cluster framework is stable at least up to 300 °C under inert atmosphere; however, it is reduced to metallic rhenium at 250–300 °C under hydrogen. The activated clusters are characterized by X-ray diffraction analyses, Raman spectrometry, extended X-ray absorption fine structure analysis, thermogravimetry–differential thermal analysis, infrared spectrometry, acid titration with Hammett indicators, and elemental analyses.

  15. Studies on Zn(II monohydroxyphenyl mesoporphyrinic complexes. Synthesis and characterization

    Directory of Open Access Journals (Sweden)

    RICA BOSCENCU

    2008-07-01

    Full Text Available A series of four Zn(II complexes with asymmetrical porphyrinic ligands were synthesized: [5-(4-hydroxyphenyl-10,15,20-triphenyl-21H,23H-porphinato]Zn(II (Zn(IITPPOHP, [5-(3-hydroxyphenyl-10,15,20-triphenyl-21H,23H-porphinato]Zn(II (Zn(IITPPOHM, [5-(2-hydroxyphenyl-10,15,20-triphenyl-21H,23H-Zn(II-porphinato]Zn(II (Zn(IITPPOHO and the well-known (5,10,15,20-tetraphenyl-21H,23H-porphinato]Zn(II (Zn(IITPP as reference, in a 1:1 mole ratio. In all cases, the free-base porphyrin served as a tetradentate ligand through the four pyrrole nitrogen atoms. The complexes were characterized by elemental analysis, FTIR and UV–Vis spectroscopy, which fully confirmed the structure of the complexes. UV–Vis showed that the spectral absorption of the four complexes was blue-shifted by at least 50 nm compared to that of the free ligands. Also important structural data were obtained from several different NMR experiments (including 1H-NMR, 13C-NMR, DEPT, COSY, HMBC and HMQC. Influences of external substituents on the porphyrin ring were observed.

  16. Characterization and Antioxidant Activity of the Complex of ...

    African Journals Online (AJOL)

    Purpose: To improve the aqueous solubility of phloridzin by complexing it with hydroxypropyl-β-cyclodextrin Methods: The complex of phloridzin with HP-β-CD was prepared by freeze-drying method. The physicochemical properties of the complex were investigated by ultraviolet-visible spectrometry (UV), infrared ...

  17. Preparation and Characterization of Double Metal Cyanide Complex Catalysts

    Directory of Open Access Journals (Sweden)

    Weilin Guo

    2003-01-01

    Full Text Available A series of double metal cyanide (DMC complex catalysts were prepared in two different methods by using ß-cyclodextrin, PEG-1000 and Tween-60 as an additional complex ligands respectively. It was showed that a mixture of crystalline and amorphous DMC was synthesized by using traditional method in which the additional complex ligand was added after the precipitation of DMC. Amorphous and dispersed DMC with higher activity could be obtained when the additional complex ligand was added in the reactant solution before reaction. The effect of additional complex ligand and preparation method on the crystalline state and catalytic property of DMC were also investigated.

  18. Synthesis, characterization, DFT calculations and antibacterial activity of palladium(II) cyanide complexes with thioamides

    Science.gov (United States)

    Ahmad, Saeed; Nadeem, Shafqat; Anwar, Aneela; Hameed, Abdul; Tirmizi, Syed Ahmed; Zierkiewicz, Wiktor; Abbas, Azhar; Isab, Anvarhusein A.; Alotaibi, Mshari A.

    2017-08-01

    Palladium(II) cyanide complexes of thioamides (or thiones) having the general formula PdL2(CN)2, where L = Thiourea (Tu), Methylthiourea (Metu), N,N‧-Dimethylthiourea (Dmtu), Tetramethylthiourea (Tmtu), 2-Mercaptopyridine (Mpy) and 2-Mercaptopyrimidine (Mpm) were prepared by reacting K2[PdCl4] with potassium cyanide and thioamides in the molar ratio of 1:2:2. The complexes were characterized by elemental analysis, thermal and spectroscopic methods (IR, 1H and 13C NMR). The structures of three of the complexes were predicted by DFT calculations. The appearance of a band around 2100 cm-1 in IR and resonances around 120-130 ppm in the 13C NMR spectra indicated the coordination of cyanide to palladium(II). More than one resonances were observed for CN- carbon atoms in 13C NMR indicating the existence of equilibrium between different species in solution. DFT calculations revealed that in the case of the palladium(II) complex of Tmtu, the ionic dinuclear [Pd(Tmtu)4][Pd(CN)4] form was more stable than the dimer of mononuclear complex [Pd(Tmtu)2(CN)2] by 0.91 kcal mol-1, while for the complexes of Tu or Mpy ligands, the nonionic [Pd(L)2(CN)2] forms were more stable than the corresponding [Pd(L)4][Pd(CN)4] complexes by 1.26 and 6.49 kcal mol-1 for L = Tu and Mpy, respectively. The complexes were screened for antibacterial effects and some of them showed significant activities against both gram positive as well as gram negative bacteria.

  19. Synthesis, characterization and biocidal activity of some transition metal(II) complexes with isatin salicylaldehyde acyldihydrazones.

    Science.gov (United States)

    Singh, Vinod P; Singh, Shweta; Singh, Divya P

    2012-06-01

    Cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) complexes with two new unsymmetrical ligands, isatin salicylaldehyde oxalic acid dihydrazide (isodh) and isatin salicylaldehyde malonic acid dihydrazide (ismdh) were synthesized and characterized by elemental analyses, electrical conductance, magnetic moments, electronic, NMR, ESR and IR spectral studies. The isodh acts as a dibasic tetra dentate ligand bonding through two >C=N-, a deprotonated phenolate and deprotonated indole enolate groups to the metal. The ismdh ligand shows monobasic tetra dentate behaviour in bonding with metal ion through two >C=N-, indole >C=O and a deprotonated phenolate group. The electronic spectral data suggest 4-coordinate square planar geometry for Co(II), Ni(II) and Cu(II) complexes of isodh, whereas, 6-coordinate octahedral structure for the ismdh complexes. The ESR studies also indicate a square planar and distorted octahedral environment around Cu(II) for isodh and ismdh complexes, respectively. Most of the metal complexes show better antifungal activity than the standard and a significant antibacterial activity against various fungi and bacteria.

  20. Synthesis, characterization and biological evaluation of ruthenium flavanol complexes against breast cancer

    Science.gov (United States)

    Singh, Ashok Kumar; Saxena, Gunjan; Sahabjada; Arshad, M.

    2017-06-01

    Four Ru(II) DMSO complexes (M1R-M4R) having substituted flavones viz. 3-Hydroxy-2-(4-methoxyphenyl)-4H-chromen-4-one (HL1), 3-Hydroxy-2-(4-nitrophenyl)-4H-chromen-4-one (HL2), 3-Hydroxy-2-(4-dimethylaminophenyl)-4H-chromen-4-one (HL3) and 3-Hydroxy-2-(4-chlorophenyl)-4H-chromen-4-one (HL4) were synthesized and characterized by elemental analysis, IR, UV-Vis, 1H NMR spectroscopies and ESI-MS. The molecular structures of the complexes were investigated by integrated spectroscopic and computational techniques (DFT). Both ligands as well as their complexes were screened for anticancer activities against breast cancer cell lines MCF-7. Cytotoxicity was assayed by MTT [3-(4, 5-dimethyl thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide] assay. All ligands and their complexes exhibited significant cytotoxic potential of 5-40 μM concentration at incubation period of 24 h. The cell cytotoxicity increased significantly in a concentration-dependent manner. In this series of compounds, HL2 (IC50 17.2 μM) and its complex M2R (IC50 16 μM) induced the highest cytotoxicity.

  1. Characterization of strained semiconductor structures using transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Oezdoel, Vasfi Burak

    2011-08-15

    Today's state-of-the-art semiconductor electronic devices utilize the charge transport within very small volumes of the active device regions. The structural, chemical and optical material properties in these small dimensions can critically affect the performance of these devices. The present thesis is focused on the nanometer scale characterization of the strain state in semiconductor structures using transmission electron microscopy (TEM). Although high-resolution TEM has shown to provide the required accuracy at the nanometer scale, optimization of imaging conditions is necessary for accurate strain measurements. An alternative HRTEM method based on strain mapping on complex-valued exit face wave functions is developed to reduce the artifacts arising from objective lens aberrations. However, a much larger field of view is crucial for mapping strain in the active regions of complex structures like latest generation metal-oxide-semiconductor field-effect transistors (MOSFETs). To overcome this, a complementary approach based on electron holography is proposed. The technique relies on the reconstruction of the phase shifts in the diffracted electron beams from a focal series of dark-field images using recently developed exit-face wave function reconstruction algorithm. Combining high spatial resolution, better than 1 nm, with a field of view of about 1 {mu}m in each dimension, simultaneous strain measurements on the array of MOSFETs are possible. Owing to the much lower electron doses used in holography experiments when compared to conventional quantitative methods, the proposed approach allows to map compositional distribution in electron beam sensitive materials such as InGaN heterostructures without alteration of the original morphology and chemical composition. Moreover, dark-field holography experiments can be performed on thicker specimens than the ones required for high-resolution TEM, which in turn reduces the thin foil relaxation. (orig.)

  2. Nickel (II and Iron (II Complexes with Azole Derivatives: Synthesis, Crystal Structures and Antifungal Activities

    Directory of Open Access Journals (Sweden)

    Emmanuel N. Nfor

    2013-01-01

    Full Text Available Two new complexes of nickel (II with 4-amino-3, 5-bis(pyridyl-1, 2, 4-triazole (abpt and iron (II with 2-(3-phenyl-1H-pyrazole-5-yl pyridine (phpzpy have been synthesized and characterized by elemental analysis and IR spectroscopy. The crystal structures of the complexes have been determined by single crystal X-ray diffraction techniques. In the nickel and iron complexes, the ligands are coordinated through nitrogen atoms in bidentate manner. The ligands and their respective complexes have been tested for their antifungal activity against Aspergillus niger, Aspergillus flavus, and Candida albicans. From the study, the complexes showed enhanced activities against the tested organisms compared to the ligands.

  3. Structural evolution of Mesozoic complexes in Western Chukotka

    Science.gov (United States)

    Golionko, B. G.; Vatrushkina, E. V.; Verzhbitsky, V. E.; Degtiarev, K. E.

    2017-07-01

    Detailed structural investigations were carried out in the Pevek area in order to verify the tectonic evolution of the Mesozoic thrust and fold belt in Chukotka. South-vergent F1 folds in Triassic rocks were proved to be the earliest structures formed during the first deformation stage DI. These structures were deformed by north-vergent folds F2 that were formed during the second deformation stage DII. North-vergent folds are the main structures of the Jurassic-Lower Cretaceous complex. The fold structures of the first two stages are deformed by shear folds F3 finishing the stage DII. All these structures are deformed by submeridionally trending normal faults referred to the deformation stage DIII.

  4. A Neutrally Charged Trimethylmanganese(III) Complex: Synthesis, Characterization, and Disproportionation Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Stalzer, Madelyn M.; Telser, Joshua; Krzystek, Jurek; Motta, Alessandro; Delferro, Massimiliano; Marks, Tobin J.

    2016-08-22

    The synthesis and properties of an unusual, neutrally charged and volatile N,N,N',N'-tetramethylethylenediamine trimethyl manganese(III) complex, (TMEDA)MnMe3, are described, along with its facile disproportionation to the corresponding Mn(II) and Mn(IV) complexes. Characterization by single-crystal XRD, UV-vis spectroscopy, high-frequency and -field EPR (HFEPR), magnetic susceptibility, and density functional theory (DFT) computations indicate that the (TMEDA)MnMe3 electronic structure can be described as largely square pyramidal Mn(III) centered. The paucity of manganese(III) polyalkyls and the simplicity and reactivity of this compound implicate it as a potentially useful synthetic building block.

  5. Bis(pentamethylene)urea complexes of the lanthanide nitrates: synthesis, characterization, properties

    Science.gov (United States)

    de Souza, H. K. S.; Pedrosa, A. M. Garrido; Marinho, E. P.; Batista, M. K. S.; Melo, D. M. Araújo; Zinner, K.; Zinner, L. B.; Zukerman-Schpector, J.; Vicentini, G.

    2003-02-01

    Lanthanide nitrate complexes of bis(pentamethylene)urea (BPMU) with general formula Ln(NO 3) 33BPMU, where Ln: La, Nd, Sm, Eu, Ho and Er have been prepared and characterized based on CHN elemental analyses, lanthanide titration with EDTA, molar conductivity, spectroscopic data and thermal studies. The infrared spectra show that ligands (BPMU) are bonded through the carbonyl oxygen, nitrate counter-ions are bidentate linked to the central ions. The structure of the neodymium complex was determined. The crystal is monoclinic, P2 1/c, Z=4, with the following parameters: a=10.148(1) Å, b=21.879(2), c=19.154(2) Å, β=104.11(1)°, V=4124.3(7) Å 3. The polyhedron is a distorted tricapped trigonal prism, coordination number nine.

  6. Syntheses, characterization and antifungal activity of novel dimethylbis(N-R-sulfonyldithiocarbimato)stannate(IV) complexes

    Science.gov (United States)

    Bomfim Filho, Lucius F. O.; Oliveira, Marcelo R. L.; Miranda, Liany D. L.; Vidigal, Antonio E. C.; Guilardi, Silvana; Souza, Rafael A. C.; Ellena, Javier; Ardisson, José D.; Zambolim, Laércio; Rubinger, Mayura M. M.

    2017-02-01

    Four new complexes of the general formula: (Ph4P)2[Sn(CH3)2(RSO2Ndbnd CS2)2], where Ph4P = tetraphenylphosphonium cation and R = CH3, (1), CH3CH2 (2), C6H5 (3), 4-FC6H4 (4), were prepared by the reaction of the appropriate potassium N-R-sulfonyldithiocarbimates, K2(RSO2Ndbnd CS2), and tetraphenylphosphonium chloride with dimethyltin dichloride. The compounds 1-4 were characterized by 1H, 13C and 119Sn NMR, 119Sn Mössbauer, vibrational spectroscopy and by elemental analyses of C, H, N and Sn. The crystal structure of 1 was determined by X-ray diffraction techniques. The in vitro antifungal activity of the tin(IV) complexes were evaluated against the fungi Rhizoctonia solani and Botrytis cinerea by the Poisoned food test. The new compounds showed comparable activities to the fungicides manzate and ziram.

  7. Extending the Concept of Diversity Partitioning to Characterize Phenotypic Complexity.

    Science.gov (United States)

    Marion, Zachary H; Fordyce, James A; Fitzpatrick, Benjamin M

    2015-09-01

    Most components of an organism's phenotype can be viewed as the expression of multiple traits. Many of these traits operate as complexes, where multiple subsidiary parts function and evolve together. As trait complexity increases, so does the challenge of describing complexity in intuitive, biologically meaningful ways. Traditional multivariate analyses ignore the phenomenon of individual complexity and provide relatively abstract representations of variation among individuals. We suggest adopting well-known diversity indices from community ecology to describe phenotypic complexity as the diversity of distinct subsidiary components of a trait. Using a hierarchical framework, we illustrate how total trait diversity can be partitioned into within-individual complexity (α diversity) and between-individual components (β diversity). This approach complements traditional multivariate analyses. The key innovations are (i) addition of individual complexity within the same framework as between-individual variation and (ii) a group-wise partitioning approach that complements traditional level-wise partitioning of diversity. The complexity-as-diversity approach has potential application in many fields, including physiological ecology, ecological and community genomics, and transcriptomics. We demonstrate the utility of this complexity-as-diversity approach with examples from chemical and microbial ecology. The examples illustrate biologically significant differences in complexity and diversity that standard analyses would not reveal.

  8. Studies on the structure and function of pyruvate dehydrogenase complexes

    NARCIS (Netherlands)

    Abreu, de R.

    1978-01-01

    The aim of the present investigation was to obtain more information of the structure and function of the pyruvate dehydrogenase complexes from Azotobacter vinelandii and Escherichia coli.

    In chapter 2 a survey is given of the recent literature on

  9. Synthesis and structural study of platinum group metal complexes ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 126; Issue 4. Synthesis and structural study of platinum group metal complexes containing pyrimidine bridged pyrazolyl-pyridine ligand and 5 and 6 - cyclic hydrocarbons. Thirumala Prasad Kota Mohan Rao Kollipara. Volume 126 Issue 4 July 2014 pp 1143-1151 ...

  10. Structure, Agency, Complexity Theory and Interdisciplinary Research in Education Studies

    Science.gov (United States)

    Smith, John A.

    2013-01-01

    This article argues that Education Studies needs to develop its existing interdisciplinarity understanding of structures and agencies by giving greater attention to the modern process theories of self-organisation in the physical, biological, psychological and social sciences, sometimes given the umbrella term "complexity theory". The…

  11. Complex Colloidal Structures by Self-assembly in Electric Fields

    NARCIS (Netherlands)

    Vutukuri, H.R.

    2012-01-01

    The central theme of this thesis is exploiting the directed self-assembly of both isotropic and anisotropic colloidal particles to achieve the fabrication of one-, two-, and three-dimensional complex colloidal structures using external electric fields and/or a simple in situ thermal annealing

  12. Fitting Meta-Analytic Structural Equation Models with Complex Datasets

    Science.gov (United States)

    Wilson, Sandra Jo; Polanin, Joshua R.; Lipsey, Mark W.

    2016-01-01

    A modification of the first stage of the standard procedure for two-stage meta-analytic structural equation modeling for use with large complex datasets is presented. This modification addresses two common problems that arise in such meta-analyses: (a) primary studies that provide multiple measures of the same construct and (b) the correlation…

  13. Shear wave velocity structure of the Bushveld Complex, South Africa

    CSIR Research Space (South Africa)

    Kgaswane, EM

    2012-07-01

    Full Text Available The structure of the crust in the environs of the Bushveld Complex has been investigated by jointly inverting high-frequency teleseismic receiver functions and 2–60 s period Rayleigh wave group velocities for 16 broadband seismic stations located...

  14. Analyzing Complex and Structured Data via Unsupervised Learning Techniques

    Science.gov (United States)

    Polsterer, Kai Lars; Gieseke, Fabian; Gianniotis, Nikos; Kügler, Dennis

    2015-08-01

    In the last decades more and more dedicated all-sky-surveys created an enormous amount of data which is publicly available on the internet. The resulting datasets contain spatial, spectral, and temporal information which exhibit complex structures in the respective domain. The capability to deal with morphological features, spectral signatures, and complex time series data has become very important but is still a challenging task. A common approach when processing this kind of structured data is to extract representative features and use those for a further analysis. We present unsupervised learning approaches that help to visualize / cluster these complex data sets by e.g. deriving rotation / translation invariant prototypes or capturing the latent dynamics of time series without employing features and using echo-state-networks instead.

  15. Ranking influential nodes in complex networks with structural holes

    Science.gov (United States)

    Hu, Ping; Mei, Ting

    2018-01-01

    Ranking influential nodes in complex networks is of great theoretical and practical significance to ensure the safe operations of networks. In view of the important role structural hole nodes usually play in information spreading in complex networks, we propose a novel ranking method of influential nodes using structural holes called E-Burt method, which can be applied to weighted networks. This method fully takes into account the total connectivity strengths of the node in its local scope, the number of the connecting edges and the distributions of the total connectivity strengths on its connecting edges. The simulation results on the susceptible-infectious-recovered (SIR) dynamics suggest that the proposed E-Burt method can rank influential nodes more effectively and accurately in complex networks.

  16. Hydroxyflavone metal complexes - molecular structure, antioxidant activity and biological effects.

    Science.gov (United States)

    Samsonowicz, Mariola; Regulska, Ewa; Kalinowska, Monika

    2017-08-01

    High content of hydroxyflavones in fruits, vegetables, cereals and herbs makes them a common component of the human diet. Because of their antioxidant, antiviral, antibacterial, anti-inflammatory, anticancer properties they still pay an attention of many scientific centers. Hydroxyflavones may form complexes with metal cations, and their chelating properties differ significantly depending on the number and position of hydroxyl substituents in the ring. Synthesis of new complexes of hydroxyflavones allows for improvement biological properties, stability, water-solubility, hydrophilicity, bioavailability comparing with the parent hydroxyflavones. It expands the applicability of hydroxyflavones as food additives, diet supplements, preservatives or drug. This paper reviews on the procedures of synthesis of metal complexes with hydroxyflavones, their molecular structure, mode of coordinations, spectroscopic properties and their biological activity. The dependency between the biological activity of these compounds and their molecular structure is discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Synthesis, structures, and luminescent properties of lanthanide complexes with triphenylphospine oxide

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Yan; Xu, Shan; Wang, Xin; Li, Yue-Xue; Jin, Qiong-Hua [Department of Chemistry, Capital Normal University, Beijing (China); Liu, Min [The College of Materials Science and Engineering, Beijing University of Technology (China); Xin, Xiu-Lan [School of Food and Chemical Engineering, Beijing Technology and Business University (China)

    2017-07-03

    Seven lanthanide complexes [Ln(OPPh{sub 3}){sub 3}(NO{sub 3}){sub 3}] (1-3) (OPPh{sub 3} = triphenylphosphine oxide, Ln = Nd, Sm, Gd), [Dy(OPPh{sub 3}){sub 4}(NO{sub 3}){sub 2}](NO{sub 3}) (4), [Ln(OPPh{sub 3}){sub 3}(NO{sub 3}){sub 3}]{sub 2} (5-7) (Ln = Pr, Eu, Gd) were synthesized by the reactions of different lanthanide salts and OPPh{sub 3} ligand in the air. These complexes were characterized by single-crystal X-ray diffraction analysis, elemental analysis, IR and fluorescence spectra. Structure analysis shows that complexes 1-4 are mononuclear complexes formed by OPPh{sub 3} ligands and nitrates. The asymmetric units of complexes 5-7 consist of two crystallographic-separate molecules. Complex 1 is self-assembled to construct a 2D layer-structure of (4,4) net topology by hydrogen bond interactions. The other complexes show a 1D chain-like structure that was assembled by OPPh{sub 3} ligands and nitrate ions through C-H..O interactions. Solid emission spectra of compounds 4 and 6 are assigned to the characteristic fluorescence of Tb{sup 3+} (λ{sub em} = 480, 574 nm) and Eu{sup 3+} (λ{sub em} = 552, 593, 619, 668 nm). (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Delivery of siRNA Complexed with Palmitoylated α-Peptide/β-Peptoid Cell-Penetrating Peptidomimetics: Membrane Interaction and Structural Characterization of a Lipid-Based Nanocarrier System

    DEFF Research Database (Denmark)

    Jing, Xiaona; Foged, Camilla; Martin-Bertelsen, Birte

    2016-01-01

    . Cryo-transmission electron microscopy (cryo-TEM) revealed multilamellar, onion-like spherical vesicles, and small-angle X-ray scattering (SAXS) analysis confirmed that the majority of the lipids in the nanocarriers were organized in lamellar structures, yet coexisted with a hexagonal phase, which...

  19. Challenges in Characterizing and Controlling Complex Cellular Systems

    Science.gov (United States)

    Wikswo, John

    2011-03-01

    Multicellular dynamic biological processes such as developmental differentiation, wound repair, disease, aging, and even homeostasis can be represented by trajectories through a phase space whose extent reflects the genetic, post-translational, and metabolic complexity of the process - easily extending to tens of thousands of dimensions. Intra- and inter-cellular sensing and regulatory systems and their nested, redundant, and non-linear feed-forward and feed-back controls create high-dimensioned attractors in this phase space. Metabolism provides free energy to drive non-equilibrium processes and dynamically reconfigure attractors. Studies of single molecules and cells provide only minimalist projections onto a small number of axes. It may be difficult to infer larger-scale emergent behavior from linearized experiments that perform only small amplitude perturbations on a limited number of the dimensions. Complete characterization may succeed for bounded component problems, such as an individual cell cycle or signaling cascade, but larger systems problems will require a coarse-grained approach. Hence a new experimental and analytical framework is needed. Possibly one could utilize high-amplitude, multi-variable driving of the system to infer coarse-grained, effective models, which in turn can be tested by their ability to control systems behavior. Navigation at will between attractors in a high-dimensioned dynamical system will provide not only detailed knowledge of the shape of attractor basins, but also measures of underlying stochastic events such as noise in gene expression or receptor binding and how both affect system stability and robustness. Needed for this are wide-bandwidth methods to sense and actuate large numbers of intracellular and extracellular variables and automatically and rapidly infer dynamic control models. The success of this approach may be determined by how broadly the sensors and actuators can span the full dimensionality of the phase space

  20. Soil structure characterized using computed tomographic images

    Science.gov (United States)

    Zhanqi Cheng; Stephen H. Anderson; Clark J. Gantzer; J. W. Van Sambeek

    2003-01-01

    Fractal analysis of soil structure is a relatively new method for quantifying the effects of management systems on soil properties and quality. The objective of this work was to explore several methods of studying images to describe and quantify structure of soils under forest management. This research uses computed tomography and a topological method called Multiple...

  1. Hydrothermal synthesis, structure and characterization of new ...

    Indian Academy of Sciences (India)

    Unknown

    The structure has tunnel-type cavities and are congenial for ion transportation through them. The compound exhibits moderate thermal stability. Keywords. Hydrothermal; crystal structure; solid electrolyte; iron (III) pyrophosphate. 1. Introduction. NASICON and related compounds belong to the well known family of solid ...

  2. Novel Organotin(IV) Schiff Base Complexes with Histidine Derivatives: Synthesis, Characterization, and Biological Activity

    Science.gov (United States)

    Garza-Ortiz, Ariadna; Camacho-Camacho, Carlos; Sainz-Espuñes, Teresita; Rojas-Oviedo, Irma; Gutiérrez-Lucas, Luis Raúl; Gutierrez Carrillo, Atilano; Vera Ramirez, Marco A.

    2013-01-01

    Five novel tin Schiff base complexes with histidine analogues (derived from the condensation reaction between L-histidine and 3,5-di-tert-butyl-2-hydroxybenzaldehyde) have been synthesized and characterized. Characterization has been completed by IR and high-resolution mass spectroscopy, 1D and 2D solution NMR (1H, 13C  and 119Sn), as well as solid state 119Sn NMR. The spectroscopic evidence shows two types of structures: a trigonal bipyramidal stereochemistry with the tin atom coordinated to five donating atoms (two oxygen atoms, one nitrogen atom, and two carbon atoms belonging to the alkyl moieties), where one molecule of ligand is coordinated in a three dentate fashion. The second structure is spectroscopically described as a tetrahedral tin complex with four donating atoms (one oxygen atom coordinated to the metal and three carbon atoms belonging to the alkyl or aryl substituents), with one molecule of ligand attached. The antimicrobial activity of the tin compounds has been tested against the growth of bacteria in vitro to assess their bactericidal properties. While pentacoordinated compounds 1, 2, and 3 are described as moderate effective to noneffective drugs against both Gram-positive and Gram-negative bacteria, tetracoordinated tin(IV) compounds 4 and 5 are considered as moderate effective and most effective compounds, respectively, against the methicillin-resistant Staphylococcus aureus strains (Gram-positive). PMID:23864839

  3. Genetic and phenotypic characterization of complex hereditary spastic paraplegia

    National Research Council Canada - National Science Library

    Kara, Eleanna; Tucci, Arianna; Manzoni, Claudia; Lynch, David S; Elpidorou, Marilena; Bettencourt, Conceicao; Chelban, Viorica; Manole, Andreea; Hamed, Sherifa A; Haridy, Nourelhoda A; Federoff, Monica; Preza, Elisavet; Hughes, Deborah; Pittman, Alan; Jaunmuktane, Zane; Brandner, Sebastian; Xiromerisiou, Georgia; Wiethoff, Sarah; Schottlaender, Lucia; Proukakis, Christos; Morris, Huw; Warner, Tom; Bhatia, Kailash P; Korlipara, L V Prasad; Singleton, Andrew B; Hardy, John; Wood, Nicholas W; Lewis, Patrick A; Houlden, Henry

    2016-01-01

    The hereditary spastic paraplegias are a heterogeneous group of degenerative disorders that are clinically classified as either pure with predominant lower limb spasticity, or complex where spastic...

  4. Characterization of a cadmium-binding complex of cabbage leaves

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, G.J.

    1984-11-01

    The chemical nature of a principle, inducible cadmium-binding complex which accumulates in cabbage leaves was studied and compared with that of animal metallothionein and copper-binding proteins isolated from various organisms. The apparent molecular weight of native cabbage complex and carboxymethylated ligand of the complex under native conditions as determined by gel filtration was about 10,000 daltons. Under denaturing conditions their apparent molecular weights were about 2000 daltons. Ligand of native complex contained 37, 28, and 9 residue per cent of glutamic acid-glutamine, cysteine, and glycine, respectively, and low aromatic residue, serine and lysine content. The high acidic and low hydrophobic residue content explain the behavior of complex on electrophoresis in the presence and absence of sodium dodecyl sulfate. Its isoelectric point was below 4.0 and it bound 4 to 6 moles cadmium per mole ligand in what appear to be cadmium-mercaptide chromophores. The complex was found to be heat stable, relatively protease insensitive, and lacking in disulfide bonds. Attempts to determine the primary sequence of reduced native complex and carboxymethylated, cleaved ligand using the Edman degradation procedure were unsuccessful. An electrophoretic procedure is described for preparative isolation of purified complex and a method is described for monitoring ligand of complex as its fluorescent dibromobimane adduct. 31 references, 6 figures, 2 tables.

  5. Structure function relationship in complex brain networks expressed by hierarchical synchronization

    Science.gov (United States)

    Zhou, Changsong; Zemanová, Lucia; Zamora-López, Gorka; Hilgetag, Claus C.; Kurths, Jürgen

    2007-06-01

    The brain is one of the most complex systems in nature, with a structured complex connectivity. Recently, large-scale corticocortical connectivities, both structural and functional, have received a great deal of research attention, especially using the approach of complex network analysis. Understanding the relationship between structural and functional connectivity is of crucial importance in neuroscience. Here we try to illuminate this relationship by studying synchronization dynamics in a realistic anatomical network of cat cortical connectivity. We model the nodes (cortical areas) by a neural mass model (population model) or by a subnetwork of interacting excitable neurons (multilevel model). We show that if the dynamics is characterized by well-defined oscillations (neural mass model and subnetworks with strong couplings), the synchronization patterns are mainly determined by the node intensity (total input strengths of a node) and the detailed network topology is rather irrelevant. On the other hand, the multilevel model with weak couplings displays more irregular, biologically plausible dynamics, and the synchronization patterns reveal a hierarchical cluster organization in the network structure. The relationship between structural and functional connectivity at different levels of synchronization is explored. Thus, the study of synchronization in a multilevel complex network model of cortex can provide insights into the relationship between network topology and functional organization of complex brain networks.

  6. Structural characterization and thermally stimulated discharge ...

    Indian Academy of Sciences (India)

    The electrical conductivity of naphthalene doped polystyrene (PS) films (≈ 61.58 m thick) was studied as a function of dopant concentration and temperature. The formation of charge transfer (CT) complexes and strong concentration dependence of carrier mobility point out that the current carriers are transported through ...

  7. Significance tests for functional data with complex dependence structure

    KAUST Repository

    Staicu, Ana-Maria

    2015-01-01

    We propose an L (2)-norm based global testing procedure for the null hypothesis that multiple group mean functions are equal, for functional data with complex dependence structure. Specifically, we consider the setting of functional data with a multilevel structure of the form groups-clusters or subjects-units, where the unit-level profiles are spatially correlated within the cluster, and the cluster-level data are independent. Orthogonal series expansions are used to approximate the group mean functions and the test statistic is estimated using the basis coefficients. The asymptotic null distribution of the test statistic is developed, under mild regularity conditions. To our knowledge this is the first work that studies hypothesis testing, when data have such complex multilevel functional and spatial structure. Two small-sample alternatives, including a novel block bootstrap for functional data, are proposed, and their performance is examined in simulation studies. The paper concludes with an illustration of a motivating experiment.

  8. Hormone Anchored Metal Complexes. 1. Synthesis, Structure, Spectroscopy and In Vitro Antitumor Activity of Testosterone Acetate Thiosemicarbazone and its Metal Complexes

    OpenAIRE

    Murugkar, Anupa; Unnikrishnan, Bindu; Padhye, Subhash; Bhonde, Ramesh; Teat, Simon; Triantafillou, Evangelia; Sinn, Ekkehard

    1999-01-01

    Testosterone acetate thiosemicarbazone (TATSC, 17-β-hydroxyandrost-4-one acetate thiosemicarbazone) was synthesized and characterized by single crystal X-ray structure determination. The copper and platinum complexes of this steroid derivative were synthesized and characterized by spectroscopy and electrochemiatry. The in vitro activity of these compounds against human breast cancer cell line MCF-7 was tested. The highest activity was found for the [Pt(TATSC)Cl1] followed by [Cu(TATSC)Cl2] an...

  9. On the structure of thorium and americium adenosine triphosphate complexes.

    Science.gov (United States)

    Mostapha, Sarah; Fontaine-Vive, Fabien; Berthon, Laurence; Boubals, Nathalie; Zorz, Nicole; Solari, Pier Lorenzo; Charbonnel, Marie Christine; Den Auwer, Christophe

    2014-11-01

    The actinides are chemical poisons and radiological hazards. One challenge to better appraise their toxicity and develop countermeasures in case of exposure of living organisms is to better assess pathways of contamination. Because of the high chemical affinity of those actinide elements for phosphate groups and the ubiquity of such chemical functions in biochemistry, nucleotides and in particular adenosine triphosphate nucleotide (ATP) may be considered critical target building blocks for actinides. Combinations of spectroscopic techniques (Fourier transformed Infra Red [FTIR], Electrospray Ionization Mass Spectrometry [ESI-MS], and Extended X-ray Absorption Fine Structure [EXAFS]) with quantum chemical calculations have been implemented in order to assess the actinides coordination arrangement with ATP. We describe and compare herein the interaction of ATP with thorium and americium; thorium(IV) as a representative of actinide(IV) like plutonium(IV) and americium(III) as a representative of all heavier actinides. In the case of thorium, an insoluble complex is readily formed. In the case of americium, a behavior identical to that described previously for lutetium has been observed with insoluble and soluble complexes. The comparative study of ATP complexation with Th(IV) and Am(III) shows their ability to form insoluble complexes for which a structural model has been proposed by analogy with previously described Lu(III) complexes.

  10. Polyacrylic acids–bovine serum albumin complexation: Structure and dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Othman, Mohamed; Aschi, Adel, E-mail: aschi13@yahoo.fr; Gharbi, Abdelhafidh

    2016-01-01

    The study of the mixture of BSA with polyacrylic acids at different masses versus pH allowed highlighting the existence of two regimes of weak and strong complexation. These complexes were studied in diluted regime concentration, by turbidimetry, dynamic light scattering (DLS), zeta-potential measurements and nuclear magnetic resonance (NMR). We have followed the pH effect on the structure and properties of the complex. This allowed refining the interpretation of the phase diagram and understanding the observed phenomena. The NMR measurements allowed probing the dynamics of the constituents versus the pH. The computational method was used to precisely determine the electrostatic potential of BSA and how the polyelectrolyte binds to it at different pH. - Highlights: • Influence of physico-chemical parameters on the electrostatic interactions in the complex system (polyelectrolyte/protein). • Stabilization and encapsulation of biological macromolecules solution by mean of polyelectrolyte. • Properties and structure of mixture obtained by screening the charges of globular protein and at different masses of polyacrylic acids. • Dynamic of the constituents formed by complexes particles. • Evaluation of the electrostatic properties of bovine serum albumin versus pH through solution of the Poisson-Boltzmann equation.

  11. Bim Automation: Advanced Modeling Generative Process for Complex Structures

    Science.gov (United States)

    Banfi, F.; Fai, S.; Brumana, R.

    2017-08-01

    The new paradigm of the complexity of modern and historic structures, which are characterised by complex forms, morphological and typological variables, is one of the greatest challenges for building information modelling (BIM). Generation of complex parametric models needs new scientific knowledge concerning new digital technologies. These elements are helpful to store a vast quantity of information during the life cycle of buildings (LCB). The latest developments of parametric applications do not provide advanced tools, resulting in time-consuming work for the generation of models. This paper presents a method capable of processing and creating complex parametric Building Information Models (BIM) with Non-Uniform to NURBS) with multiple levels of details (Mixed and ReverseLoD) based on accurate 3D photogrammetric and laser scanning surveys. Complex 3D elements are converted into parametric BIM software and finite element applications (BIM to FEA) using specific exchange formats and new modelling tools. The proposed approach has been applied to different case studies: the BIM of modern structure for the courtyard of West Block on Parliament Hill in Ottawa (Ontario) and the BIM of Masegra Castel in Sondrio (Italy), encouraging the dissemination and interaction of scientific results without losing information during the generative process.

  12. Predicting and characterizing data sequences from structure-variable systems

    CERN Document Server

    Fangi, H P

    1995-01-01

    Abstract: In principle, all the natural systems such as biological, ecological and economical systems are structure-variable systems (in which some environment parameters are not fixed). In this Letter we show that data sequences from many structure-variable systems are short-term predictable. We also argue how to characterize the data sequences from structure-variable systems.

  13. Synthesis, characterization and biological activity of transition metal complexes with Schiff bases derived from 2-nitrobenzaldehyde with glycine and methionine

    Science.gov (United States)

    Singh, Bibhesh K.; Rajour, Hemant K.; Prakash, Anant

    Schiff bases derived from 2-nitrobenzaldehyde with amino acids (glycine, methionine) and their Co(II), Ni(II) and Cu(II) complexes have been synthesized and characterized by various physico-chemical techniques. From spectral studies, it has been concluded that the ligands acts as bidentate molecule, coordinates metal through azomethine nitrogen and carboxylate oxygen. Mass spectrum explains the successive degradation of the molecular species in solution and justifies ML2 complexes. X-ray powder diffraction helps to determine the cell parameters of the complexes. Molecular structure of the complexes has been optimized by MM2 calculations and suggests a square planar geometry. The ligands and their metal complexes have been tested in vitro against Streptococcus, Staph, Staphylococcus aureus and Escherchia coli bacteria in order to assess their antibacterial potential. The results indicate that the biological activity increases on complexation.

  14. DNA binding and cleavage activity of a structurally characterized Ni(II)

    Indian Academy of Sciences (India)

    1375–1381. c Indian Academy of Sciences. DOI 10.1007/s12039-015-0900-4. DNA binding and cleavage activity of a structurally characterized Ni(II). Schiff base complex. SARAT CHANDRA KUMARa, ABHIJIT PALa, MERRY MITRAa,. V M MANIKANDAMATHAVANb, CHIA -HER LINc, BALACHANDRAN UNNI NAIRb,∗.

  15. Palladium(II) complexes bearing a salicylaldiminato ligand with a hydroxyl group: Synthesis, structures, deprotonation, and catalysis

    OpenAIRE

    Murata, Yusuke; Ohgi, Hiroyuki; Fujihara, Tetsuaki; Terao, Jun; Tsuji, Yasushi

    2011-01-01

    Palladium complexes with a salicylaldiminato ligand bearing a hydroxyl group (1a and 1b) have been synthesized and characterized. The structures of these complexes were confirmed by X-ray crystallography. A reversible deprotonation/protonation of the hydroxyl moiety on 1b was observed, while such behaviour was impossible with a related palladium complex (1c) bearing a methoxyl group in place of the hydroxyl group. The deprotonation affected its catalytic behaviour: the activity for polymeriza...

  16. Synthesis and characterization of an iron complex bearing a cyclic tetra-N-heterocyclic carbene ligand: An artifical heme analogue?

    KAUST Repository

    Anneser, Markus R.

    2015-04-20

    An iron(II) complex with a cyclic tetradentate ligand containing four N-heterocyclic carbenes was synthesized and characterized by means of NMR and IR spectroscopies, as well as by single-crystal X-ray structure analysis. The iron center exhibits an octahedral coordination geometry with two acetonitrile ligands in axial positions, showing structural analogies with porphyrine-ligated iron complexes. The acetonitrile ligands can readily be substituted by other ligands, for instance, dimethyl sulfoxide, carbon monoxide, and nitric oxide. Cyclic voltammetry was used to examine the electronic properties of the synthesized compounds. © 2015 American Chemical Society.

  17. Characterizing Complexity of Containerized Cargo X-ray Images

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guangxing [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Martz, Harry [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Glenn, Steven [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Divin, Charles [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Birrer, Nat [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-08-19

    X-ray imaging can be used to inspect cargos imported into the United States. In order to better understand the performance of X-ray inspection systems, the X-ray characteristics (density, complexity) of cargo need to be quantified. In this project, an image complexity measure called integrated power spectral density (IPSD) was studied using both DNDO engineered cargos and stream-of-commerce (SOC) cargos. A joint distribution of cargo density and complexity was obtained. A support vector machine was used to classify the SOC cargos into four categories to estimate the relative fractions.

  18. Synthesis and characterization of tin(II) complexes of fluorinated Schiff bases derived from amino acids.

    Science.gov (United States)

    Singh, Har Lal

    2010-07-01

    New tin(II) complexes of general formula Sn(L)(2) (L=monoanion of 3-methyl-4-fluoro-acetophenone phenylalanine L(1)H, 3-methyl-4-fluoro-acetophenone alanine L(2)H, 3-methyl-4-fluoro acetophenone tryptophan L(3)H, 3-methyl-4-fluoro-acetophenone valine L(4)H, 3-methyl-4-fluoro-acetophenone isoleucine L(5)H and 3-methyl-4-fluoro-acetophenone glycine L(6)H) have been prepared. It is characterized by elemental analyses, molar conductance measurements and molecular weight determinations. Bonding of these complexes is discussed in terms of their UV-visible, infrared, and nuclear magnetic resonance ((1)H, (13)C, (19)F and (119)Sn NMR) spectral studies. The ligands act as bidentate towards metal ions, via the azomethine nitrogen and deprotonated oxygen of the respective amino acid. Elemental analyses and NMR spectral data of the ligands with their tin(II) complexes agree with their proposed square pyramidal structures. A few representative ligands and their tin complexes have been screened for their antibacterial activities and found to be quite active in this respect. Copyright 2010 Elsevier B.V. All rights reserved.

  19. Characterization and Enhanced Antioxidant Activity of the Cysteinyl β-Cyclodextrin-Baicalein Inclusion Complex

    Directory of Open Access Journals (Sweden)

    Hwanhee Kim

    2016-05-01

    Full Text Available Baicalein is a type of flavonoid isolated from the roots of a medicinal plant, Scutellaria baicalensis. Although it has attracted considerable attention due to its antiviral, anti-tumor, and anti-inflammatory activities, its limited aqueous solubility inhibits the clinical application of this flavonoid. The present study aimed to prepare and characterize a host-guest complex in an effort to improve the solubility and antioxidant activity of baicalein. The host molecule is a macrocyclic β-cyclodextrin (β-CD functionalized with cysteine for a synergetic effect. The structure of the synthesized cysteinyl β-CD was analyzed using nuclear magnetic resonance (NMR spectroscopy and mass spectrometry. The inclusion complex with baicalein was studied by UV-vis, NMR spectroscopy, scanning electron microscopy, and X-ray powder diffractometry. The formed cysteinyl β-CD/baicalein inclusion complex efficiently improved the solubility and antioxidant ability of baicalein. Therefore, we suggest that the present cysteinyl β-CD is a potential host molecule for inclusion complexation and for bioavailability augmentation.

  20. SURFACE COMPLEXITY COMPONENT OF LIDAR POINT CLOUD ERROR CHARACTERIZATION

    OpenAIRE

    C. Toth; Grejner-Brzezinska, D.

    2012-01-01

    There are several data product characterization methods to describe LiDAR data quality. Typically based on guidelines developed by government or professional societies, these techniques require the statistical analysis of vertical differences at known checkpoints (surface patches) to obtain a measure of the vertical accuracy. More advanced methods attempt to also characterize the horizontal accuracy of the LiDAR point cloud, using measurements at LiDAR-specific targets or other man-m...

  1. Characterization and Antioxidant Activity of the Complex of ...

    African Journals Online (AJOL)

    visible spectrometry (UV), infrared spectrometry (IR), differential scanning calorimetry (DSC) and x-ray diffractometry (XRD). The antioxidant activity was examined by DPPH and ABTS radical-scavenging activities. Results: Phloridzin in the complex ...

  2. Synthesis and Characterization of Mercuric Bromide-Phenothiazine Complexes

    OpenAIRE

    Vidisha A. Alwani; Kishore Cholkar; Ananth A Nayak; Netkal M. Made Gowda

    2014-01-01

    N-alkylphenothiazines (NAPTZs) are biologically active heterocyclic compounds that find extensive applications in the field of medicine. In the pharmaceutical industry, they are used as psychotherapeutic, antiemetic, and antihistaminic drugs. In this study, complexation reactions of mercuric bromide with NAPTZs as principal ligands have been investigated in MeOH medium. Five mercuric bromide complexes of the NAPTZ ligands namely, chlorpromazine hydrochloride (CP.HCl), promethazine hydrochl...

  3. Carbon nanotubes: synthesis, structure, functionalization, and characterization.

    Science.gov (United States)

    Zamolo, Valeria Anna; Vazquez, Ester; Prato, Maurizio

    2014-01-01

    Carbon nanotubes have generated great expectations in the scientific arena, mainly due to their spectacular properties, which include a high aspect ratio, high strain resistance, and high strength, along with high conductivities. Nowadays, carbon nanotubes are produced by a variety of methods, each of them with advantages and disadvantages. Once produced, carbon nanotubes can be chemically modified, using a wide range of chemical reactions. Functionalization makes these long wires much easier to manipulate and dispersible in several solvents. In addition, the properties of carbon nanotubes can be combined with those of organic appendages. Finally, carbon nanotubes need to be carefully characterized, either as pristine or modified materials.

  4. Zein/caseinate/pectin complex nanoparticles: Formation and characterization.

    Science.gov (United States)

    Chang, Chao; Wang, Taoran; Hu, Qiaobin; Luo, Yangchao

    2017-11-01

    In this study, pectin was used as coating material to form zein/caseinate/pectin complex nanoparticles through pH adjustment and heating treatment for potential oral delivery applications. The preparation conditions were studied by applying heating treatment at different pHs, either the isoelectric point of zein (pH 6.2) or caseinate (pH 4.6), or consecutively at both pHs. The particulate characteristics, including particle size, polydispersity index, and zeta potential were monitored for complex nanoparticles formed under different preparation conditions. The complex nanoparticles generally exhibited particle size smaller than 200nm with narrow distribution, spherical shape, and strong negative charge. Fourier transform infrared and fluorescence spectroscopy revealed that hydrophobic interactions and hydrogen bonds were involved in the formation of complex nanoparticles, in addition to electrostatic interactions. Fresh colloidal dispersion and freeze-dried powders varied in their morphology, depending on their preparation conditions. Our results suggested that heating pH and sequence significantly affected the morphology of complex nanoparticles, and pectin coating exerted stabilization effect under simulated gastrointestinal conditions. The present study provides insight into the formation of protein/polysaccharide complex nanoparticles under different preparation conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Characterization of complex phase steel using backscattered electron images with controlled collection angles.

    Science.gov (United States)

    Sato, Kaoru; Sueyoshi, Hitoshi; Yamada, Katsumi

    2015-10-01

    For optimizing the microstructure of complex phase (CP) steels, characterization using scanning electron microscopy (SEM) is powerful because it allows observations from very low to high magnification. SEM specimens of steels are often etched in order to distinguish between the different phases by producing topographic information. This is however an 'indirect' method of characterization, which does not give precise structural information. We have developed a new technique for the selective imaging of the martensite (M) phase in a ferritic (F)-M complex phase steel. Backscattered electron (BSE) images at 15-20 kV were recorded by systematically changing the collection angle θ, where θ is measured from the specimen surface. When θ was 30-45°, strong channeling contrast was observed. For lower values of θ, it is the low energy loss electrons that mainly contribute to the contrast. As θ increases, the M phase exhibits brighter contrast. When θ exceeds 60°, a selective imaging of the M phase is achieved. This is not because martensite has a larger mean atomic number than ferrite, but is due to the fact that martensite has a high crystallographic defect density. Anomalously bright M contrast is due to multiple scattering of BSE due to the high density of planar defects and dislocations. Low angle BSE allows high resolution characterization of complex microstructures, while high angle BSE gives quantitative assessment of the distribution and the volume fraction of the martensite phase. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. Geophysical Characterization of Controls on Biogenic gas realease in the Red Lake Peatland Complex, Northern Minnesota

    Science.gov (United States)

    Nolan, J.; Parsekian, A.; Slater, L.; Glaser, P.; O'Brian, M.

    2008-05-01

    Recently there has been an increased interest in northern peatlands with respect to their role in the global carbon balance, as they are a net sink of carbon dioxide in the biomass, and a net source of biogenic methane. Methane can store heat roughly 25 times more efficiently than carbon dioxide, making characterization of releases to the atmosphere through both diffusion and ebullition events critical to understanding the global carbon budget. The spatial and temporal heterogeneity of ebullition events make this characterization difficult, and traditional sampling schemes are inadequate due to poor spatial sampling scales, destruction of peat fabric during coring, and difficulty of working in remote ecosystems. Observations of zones of hydraulic overpressure related to free phase gas accumulation forming below confining layers in the peat suggest that peat stratigraphy a key factor controlling the spatial heterogeneity of biogenic gas ebullition. We used electrical geophysical methods to characterize the peat stratigraphy and hydrogeological framework of the Red Lake Peatland Complex in Northern Minnesota, one of the largest (140 km2) and most studied peatlands in North America. This mid-continent forested bog complex is comprised of three major peat landforms, each of which was surveyed using ground penetrating radar (GPR), electrical resistivity, and induced polarization (IP): (1) a raised, ombrotrophic, wooded crest; (2) a sphagnum lawn down slope of the bog crest; (3) a spring fen water track where water flows across the peat surface around ovoid wooded islands. GPR measurements show clearly the peat thickness as well as horizontally continuous internal reflections that indicate the presence of confining layers that may allow for over pressuring zones due to the trapping of free phase biogenic gasses. These results also form a novel data set of a well studied bog complex, offering new insights into the peat structure and hydrogeologic framework and have

  7. Structural and ethnobotanical characterization of velvet tamarind ...

    African Journals Online (AJOL)

    In order to help the sustainable management and conservation of this species, its structural characteristics and ethnobotanical traits were studied in the 4 vegetation types (typical dense forest, degraded dense forest, young fallow and old fallow) of the Lama forest reserve. A forest inventory was carried out in 100 randomly ...

  8. Synthesis, structural and surface morphological characterizations of ...

    African Journals Online (AJOL)

    Sulfated zirconia (SZ) nanoparticles (NPs) were successfully synthesized and deposited via chemical route called sol-gel technique. The structural, morphological, and optical properties the samples were investigated by X-ray diffraction (XRD), Energy Dispersive X-ray Spectrometry (EDX), Scanning Electron Microscopy ...

  9. Hydrothermal synthesis, structure and characterization of new ...

    Indian Academy of Sciences (India)

    The structure has tunnel-type cavities and are congenial for ion transportation through them. The compound exhibits moderate ... Prasad2 K G Ashamanjari1. Department of Studies in Geology, University of Mysore, Mysore 570 006, India; Department of Studies in Physics, University of Mysore, Mysore 570 006, India ...

  10. Principal Physicochemical Methods Used to Characterize Dendrimer Molecule Complexes Used as Genetic Therapy Agents, Nanovaccines or Drug Carriers.

    Science.gov (United States)

    Alberto, Rodríguez Fonseca Rolando; Joao, Rodrigues; de Los Angeles, Muñoz-Fernández María; Alberto, Martínez Muñoz; Manuel Jonathan, Fragoso Vázquez; José, Correa Basurto

    2017-08-30

    Nanomedicine is the application of nanotechnology to medicine. This field is related to the study of nanodevices and nanomaterials applied to various medical uses, such as in improving the pharmacological properties of different molecules. Dendrimers are synthetic nanoparticles whose physicochemical properties vary according to their chemical structure. These molecules have been extensively investigated as drug nanocarriers to improve drug solubility and as sustained-release systems. New therapies such as gene therapy and the development of nanovaccines can be improved by the use of dendrimers. The biophysical and physicochemical characterization of nucleic acid/peptide-dendrimer complexes is crucial to identify their functional properties prior to biological evaluation. In that sense, it is necessary to first identify whether the peptide-dendrimer or nucleic aciddendrimer complexes can be formed and whether the complex can dissociate under the appropriate conditions at the target cells. In addition, biophysical and physicochemical characterization is required to determine how long the complexes remain stable, what proportion of peptide or nucleic acid is required to form the complex or saturate the dendrimer, and the size of the complex formed. In this review, we present the latest information on characterization systems for dendrimer-nucleic acid, dendrimer-peptide and dendrimer-drug complexes with several biotechnological and pharmacological applications. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  11. Geophysical mapping of complex glaciogenic large-scale structures

    DEFF Research Database (Denmark)

    Høyer, Anne-Sophie

    2013-01-01

    is required to understand the structures. In practice, however, also the applicability and costs of the methods are crucial. The SkyTEM method is very cost-effective in providing dense data sets, and it is therefore recommendable to use this method initially in mapping campaigns. For more detailed structural...... information, seismic data can profitably be acquired in certain areas of interest, preferably selected on the basis of the SkyTEM data. In areas where extremely detailed information about the near-surface is required, geoelec¬tri¬cal data (resistivity information) and ground penetrating radar data (structural......This thesis presents the main results of a four year PhD study concerning the use of geophysical data in geological mapping. The study is related to the Geocenter project, “KOMPLEKS”, which focuses on the mapping of complex, large-scale geological structures. The study area is approximately 100 km2...

  12. Resolving complex chromosome structures during meiosis: versatile deployment of Smc5/6.

    Science.gov (United States)

    Verver, Dideke E; Hwang, Grace H; Jordan, Philip W; Hamer, Geert

    2016-03-01

    The Smc5/6 complex, along with cohesin and condensin, is a member of the structural maintenance of chromosome (SMC) family, large ring-like protein complexes that are essential for chromatin structure and function. Thanks to numerous studies of the mitotic cell cycle, Smc5/6 has been implicated to have roles in homologous recombination, restart of stalled replication forks, maintenance of ribosomal DNA (rDNA) and heterochromatin, telomerase-independent telomere elongation, and regulation of chromosome topology. The nature of these functions implies that the Smc5/6 complex also contributes to the profound chromatin changes, including meiotic recombination, that characterize meiosis. Only recently, studies in diverse model organisms have focused on the potential meiotic roles of the Smc5/6 complex. Indeed, Smc5/6 appears to be essential for meiotic recombination. However, due to both the complexity of the process of meiosis and the versatility of the Smc5/6 complex, many additional meiotic functions have been described. In this review, we provide a clear overview of the multiple functions found so far for the Smc5/6 complex in meiosis. Additionally, we compare these meiotic functions with the known mitotic functions in an attempt to find a common denominator and thereby create clarity in the field of Smc5/6 research.

  13. New bioactive silver(I) complexes: Synthesis, characterization, anticancer, antibacterial and anticarbonic anhydrase II activities

    Science.gov (United States)

    Ozdemir, Ummuhan O.; Ozbek, Neslihan; Genc, Zuhal Karagoz; İlbiz, Firdevs; Gündüzalp, Ayla Balaban

    2017-06-01

    Silver(I) complexes of alkyl sulfonic acide hydrazides were newly synthesized as homologous series. Methanesulfonic acide hydrazide (L1), ethanesulfonic acide hydrazide (L2), propanesulfonic acide hydrazide (L3) and butanesulfonic acide hydrazide (L4) were used for complexation with Ag(I) ions. The silver complexes obtained in the mol ratio of 1:2 have the structural formula as Ag(L1)2NO3 (I), Ag(L2)2NO3 (II), Ag(L3)2NO3(III), (Ag(L4)2NO3 (IV). The Ag(I) complexes exhibit distorted linear two-fold coordination in [AgL2]+ cations with uncoordinated nitrates. Ligands are chelated with silver(I) ions through unsubstituted primary nitrogen in hydrazide group. Ag(I) complexes were characterized by using elemental analysis, spectroscopic methods (FT-IR, LC-MS), magnetic susceptibility and conductivity measurements. Silver(I) complexes were optimized using PBEPBE/LanL2DZ/DEF2SV basic set performed by DFT method with the Gaussian 09 program package. The geometrical parameters, frontier molecular orbitals (HOMOs and LUMOs) and molecular electrostatic potential (MEP) mapped surfaces of the optimized geometries were also determined by this quantum set. The anticancer activities of silver(I) complexes on MCF-7 human breast cancer cell line were investigated by comparing IC50 values. The antibacterial activities of complexes were studied against Gram positive bacteria; S. aureus ATCC 6538, B. subtilis ATCC 6633, B. cereus NRRL-B-3711, E. faecalis ATCC 29212 and Gram negative bacteria; E. coli ATCC 11230, P. aeruginosa ATCC 15442, K. pneumonia ATCC 70063 by using disc diffusion method. The inhibition activities of Ag(I) complexes on carbonic anhydrase II enzyme (hCA II) were also investigated by comparing IC50 and Ki values. The biological activity screening shows that Ag(I) complex of butanesulfonicacidehydrazide (IV) has the highest activity against tested breast cancer cell lines MCF-7, Gram positive/Gram negative bacteria and carbonic anhydrase II (hCA II) isoenzyme.

  14. Characterization of a Carbon Dioxide-Hexaflourobenzene Complex Using Matrix Isolation Infrared Spectroscopy

    Science.gov (United States)

    Amicangelo, Jay C.; Gall, Bradley K.; Horn, Maryn N.

    2017-06-01

    Matrix isolation infrared spectroscopy was used to characterize a 1:1 complex of carbon dioxide (CO_2) with hexaflourobenzene (C_6F_6). Co-deposition experiments with CO_2 and {_6F_6} were performed at 20 K using argon as the matrix gas. New infrared peaks attributable to the CO_2-C_6F_6 complex were observed near the O-C-O antisymmetric stretching vibration of the CO_2 monomer and near the C-F stretching vibration of the C_6F_6 monomer. The initial identification of the newly observed infrared peaks to those of a CO_2-C_6F_6 complex was established by performing several concentration studies in which the sample-to-matrix ratios of the monomers were varied between 1:100 to 1:1600, by comparing the resulting co-deposition spectra with the spectra of the individual monomers, and by matrix annealing experiments (30 - 35 K). Co-deposition experiments were also performed using isotopically labeled carbon dioxide (^{13}CO_2) and the analogous peaks for the ^{13}CO_2-C_6F_6 complex were observed. Quantum chemical calculations were performed for the CO_2-C_6F_6 complex at the MP2/aug-cc-pVDZ level of theory in order to explore the intermolecular potential energy surface of the complex and to obtain optimized complex geometries and predicted vibrational frequencies of the complex. The calculations for the exploration of the potential energy surface involved rigid scans along the intermolecular distance and various angle coordinates for several general orientations of the two monomers. Based on these calculations, full geometry optimizations were then performed and two stable complex minima were found: one in which the CO_2 is perpendicular and centered to the C_6F_6 ring (ΔE_{int} = -7.9 kJ/mol) and one in which the CO_2 is parallel to the C_6F_6 ring but displaced from the center (ΔE_{int} = -6.0 kJ/mol). Comparing the predicted vibrational spectra for both complexes to the observed experimental spectra, particularly for the O-C-O antisymmetric stretching region, it is

  15. Rotational Spectrum and Structure of the Quinuclidine Water Complex

    Science.gov (United States)

    Consalvo, D.; Stahl, W.

    1995-12-01

    The rotational spectrum of the quinuclidine-water complex has been observed in the region 6-20 GHz using a pulsed molecular beam Fourier transform microwave (MB-FTMW) spectrometer. In order to obtain detailed structural information on the complex, spectra of quinuclidine, also called 1-azabicyclo[2.2.2]octane (ABCO), combined with both H2O and H218O were examined. The observation of a symmetric top spectrum is consistent with a complex in which water undergoes internal rotation. Using a reasonable model for the interaction potential, it has been possible to estimate the torsional barrier of water. Centrifugal distortion analysis yields a N-H bond stretching force constant of 12.3 N/m, corresponding to a stretching frequency of 116 cm-1for ABCO-H216O.

  16. Insights into the structure and architecture of the CCR4–NOT complex

    Science.gov (United States)

    Xu, Kun; Bai, Yuwei; Zhang, Aili; Zhang, Qionglin; Bartlam, Mark G.

    2014-01-01

    The CCR4–NOT complex is a highly conserved, multifunctional machinery with a general role in controlling mRNA metabolism. It has been implicated in a number of different aspects of mRNA and protein expression, including mRNA degradation, transcription initiation and elongation, ubiquitination, and protein modification. The core CCR4–NOT complex is evolutionarily conserved and consists of at least three NOT proteins and two catalytic subunits. The L-shaped complex is characterized by two functional modules bound to the CNOT1/Not1 scaffold protein: the deadenylase or nuclease module containing two enzymes required for deadenylation, and the NOT module. In this review, we will summarize the currently available information regarding the three-dimensional structure and assembly of the CCR4–NOT complex, in order to provide insight into its roles in mRNA degradation and other biological processes. PMID:24904637

  17. Insights into the structure and architecture of the CCR4-NOT complex.

    Science.gov (United States)

    Xu, Kun; Bai, Yuwei; Zhang, Aili; Zhang, Qionglin; Bartlam, Mark G

    2014-01-01

    The CCR4-NOT complex is a highly conserved, multifunctional machinery with a general role in controlling mRNA metabolism. It has been implicated in a number of different aspects of mRNA and protein expression, including mRNA degradation, transcription initiation and elongation, ubiquitination, and protein modification. The core CCR4-NOT complex is evolutionarily conserved and consists of at least three NOT proteins and two catalytic subunits. The L-shaped complex is characterized by two functional modules bound to the CNOT1/Not1 scaffold protein: the deadenylase or nuclease module containing two enzymes required for deadenylation, and the NOT module. In this review, we will summarize the currently available information regarding the three-dimensional structure and assembly of the CCR4-NOT complex, in order to provide insight into its roles in mRNA degradation and other biological processes.

  18. Community structure from spectral properties in complex networks

    Science.gov (United States)

    Servedio, V. D. P.; Colaiori, F.; Capocci, A.; Caldarelli, G.

    2005-06-01

    We analyze the spectral properties of complex networks focusing on their relation to the community structure, and develop an algorithm based on correlations among components of different eigenvectors. The algorithm applies to general weighted networks, and, in a suitably modified version, to the case of directed networks. Our method allows to correctly detect communities in sharply partitioned graphs, however it is useful to the analysis of more complex networks, without a well defined cluster structure, as social and information networks. As an example, we test the algorithm on a large scale data-set from a psychological experiment of free word association, where it proves to be successful both in clustering words, and in uncovering mental association patterns.

  19. Variable structure control of complex systems analysis and design

    CERN Document Server

    Yan, Xing-Gang; Edwards, Christopher

    2017-01-01

    This book systematizes recent research work on variable-structure control. It is self-contained, presenting necessary mathematical preliminaries so that the theoretical developments can be easily understood by a broad readership. The text begins with an introduction to the fundamental ideas of variable-structure control pertinent to their application in complex nonlinear systems. In the core of the book, the authors lay out an approach, suitable for a large class of systems, that deals with system uncertainties with nonlinear bounds. Its treatment of complex systems in which limited measurement information is available makes the results developed convenient to implement. Various case-study applications are described, from aerospace, through power systems to river pollution control with supporting simulations to aid the transition from mathematical theory to engineering practicalities. The book addresses systems with nonlinearities, time delays and interconnections and considers issues such as stabilization, o...

  20. Structural characterization of vegetation in the fynbos biome

    CSIR Research Space (South Africa)

    Campbell, BM

    1981-08-01

    Full Text Available A proposed system for the standardization of descriptive terminology for structural characterization of vegetation in the Fynbos Biome is presented in tabular form. Specific applications of the system are described and illustrations of some...

  1. Synthesis, characterization, x-ray structure and antimicrobial activity ...

    African Journals Online (AJOL)

    Purpose: To synthesize thiosemicarbazide and determine its antimicrobial properties. Methods: Pyridine-based thiosemicarbazide was synthesized, characterized and evaluated for antimicrobial activity. The structure of the synthesized compound was established by spectral analysis, namely, Fourier transform infrared ...

  2. Copper(II) and nickel(II) complexes of benzyloxybenzaldehyde-4-phenyl-3-thiosemicarbazone: Synthesis, characterization and biological activity

    Science.gov (United States)

    Prathima, B.; Subba Rao, Y.; Adinarayana Reddy, S.; Reddy, Y. P.; Varada Reddy, A.

    2010-09-01

    Benzyloxybenzaldehyde-4-phenyl-3-thiosemicarbazone ligand (L) has been synthesized from benzyloxybenzaldehyde and 4-phenyl-3-thiosemicarbazide. Complexes of this ligand with chlorides of Cu(II) and Ni(II) have been prepared. The structure of the ligand (L) is proposed based on elemental analysis, IR and 1H NMR spectra. Its complexes with Cu(II) and Ni(II) ions are characterized from the studies of electronic as well as EPR spectra. On the basis of electronic and EPR studies, rhombically distorted octahedral structure has been proposed for Cu(II) complex while the Ni(II) complex has been found to acquire an octahedral structure. The ligand and their metal complexes have been tested in vitro for their biological effects. Their antibacterial activities against Gram-negative bacteria ( Escherichia coli and Klebsiella pneumoniae) and Gram-positive bacteria ( Staphylococcus aureus and Bacillus subtilis) have been investigated. The prepared metal complexes exhibit higher antibacterial activities than the parent ligand. The in vitro antioxidant activity of free ligand and its metal(II) complexes have also been investigated and the results however reveal that the ligand exhibits greater antioxidant activity than its complexes.

  3. Ultrathin conformal coating for complex magneto-photonic structures.

    Science.gov (United States)

    Pascu, Oana; Caicedo, José Manuel; López-García, Martín; Canalejas, Víctor; Blanco, Álvaro; López, Cefe; Arbiol, Jordi; Fontcuberta, Josep; Roig, Anna; Herranz, Gervasi

    2011-11-01

    We report on an extremely fast and versatile synthetic approach, based on microwave assisted sol-gel chemistry, that allows a conformal nanometric coating of intricate three-dimensional structures. Using this methodology, we have achieved a conformal coverage of large areas of three-dimensional opals with a superparamagnetic manganese ferrite layer, yielding magneto-photonic crystals with excellent quality. The use of a ternary oxide for the ultrathin coating demonstrates the potential of this methodology to realize three-dimensional structures with complex materials that may find applications beyond photonics, such as energy, sensing or catalysis.

  4. The structure of complex networks theory and applications

    CERN Document Server

    Estrada, Ernesto

    2012-01-01

    This book deals with the analysis of the structure of complex networks by combining results from graph theory, physics, and pattern recognition. The book is divided into two parts. 11 chapters are dedicated to the development of theoretical tools for the structural analysis of networks, and 7 chapters are illustrating, in a critical way, applications of these tools to real-world scenarios. The first chapters provide detailed coverage of adjacency and metric and topologicalproperties of networks, followed by chapters devoted to the analysis of individual fragments and fragment-based global inva

  5. Synthesis and characterization of technetium(V) oxo-complexes with quadridentate Schiff-base ligands: X-ray structures of. mu. -oxo-bis-(oxo(N,N'-propane-1,3-diylbis(salicylideneiminato))technetium(V)) and chloro-oxo(N,N'-propane-1, 3-diylbis(salicylideneiminato))technetium(V)

    Energy Technology Data Exchange (ETDEWEB)

    Bandoli, G.; Nicolini, M. (Padua Univ. (Italy). Facolta di Farmacia); Mazzi, U.; Refosco, F. (Consiglio Nazionale delle Ricerche, Padua (Italy). Lab. di Chimica e Tecnologia dei Radioelementi)

    1984-11-01

    The reactions of quadridentate Schiff-base ligands derived from salicylaldehyde and diamines with (TcOCl/sub 4/)/sup -/ have been investigated. The complexes (NBu/sub 4/)(TcOCl/sub 3/(Hsalpd)), (NBu/sub 4/)(TcOCl/sub 3/ (Hsalbd)), ((TcO(salpd))/sub 2/O), (TcOCl(salpd)), and (TcOCl(salbd)) (salpd = N,N'-propane-1,3-diylbis(salicylideneiminate), salbd = N,N'-butane-1,4-diylbis(salicylideneiminate)) were isolated from the reaction mixture in ethanol. The complexes have been characterized by elemental analysis and by i.r. spectroscopy. The crystal structures of ((TcO(salpd))/sub 2/)O (1) and (TcOCl (salpd)) (2) have been determined from three dimensional X-ray data. Results are reported. The 'dimeric' structure of (1) consists of two crystallographically independent and chemically well separated TcO(salpd) moieties bridged by an oxygen atom with the bridging Tc-O-Tc angle symmetrically imposed at 180 deg. A novel feature is the presence of the almost linear O-Tc-O-Tc-O group. The technetium atoms have octahedral co-ordination, with the equatorial plane formed by the N/sub 2/O/sub 2/ donor set, and the chelate ligand, as a whole, is very nearly planar. The structure of (2) consists of discrete molecules of (TcOCl(salpd)) with a pseudo-octahedral co-ordination around technetium. The salpd ligand occupies the four equatorial positions, whereas the Cl and the oxygen are trans to each other in axial positions. The two salicylaldimine groups are bent in an 'umbrella' shape. Bond distances are given.

  6. Structural complexity and the quality of stepfather-stepchild relationships.

    Science.gov (United States)

    Clingempeel, W G; Ievoli, R; Brand, E

    1984-12-01

    This research examined the effects of structural complexity and sex of stepchild on the quality of stepfather-stepchild relationships. Sixteen simple stepfather families (the wife had custody of a child from a previous marriage, but the stepfather has no biological children) and 16 complex stepfather families (the wife had custody of a child from a previous marriage, and the stepfather was a noncustodial biological parent) with half of each type (N = 8) having a male and half having a female, 9-12-year-old target child participated in a multimethod-multimeasure assessment of the stepfather-stepchild relationship. Families were recruited from marriage license records, and data collection was accomplished in a single three-and-a-half-hour home visit. Dependent variables included: (a) questionnaire measures of love and detachment relationship dimensions independently obtained from parents, stepparents, and (step)children, and (b) proportions of positive and negative stepparent and stepchild communication behaviors derived from videotaped interaction tasks. Findings revealed that simple and complex stepfather families did not differ on any questionnaire or behavioral measures. Girls, however, engaged in a lower proportion of positive verbal and greater proportion of negative problem-solving behaviors toward their stepfathers than boys did. Stepfathers did not differ on proportions of communication behaviors emitted toward boys and girls. No sex-of-child differences were obtained on the questionnaire measures. Directions for future research on structural complexity and stepfather families are discussed.

  7. Improvement of seismic imaging of complex geologic structures

    Energy Technology Data Exchange (ETDEWEB)

    Duquet, B.

    1996-04-11

    Successful imaging of complex geologic structures by pre-stack depth migration requires a correct velocity model of the subsurface. In recent years, it has been proposed to use pre-stack depth migration of the cube of pre-stack depth migrated images and the subsequent use of the interpretation for velocity model update. However, in complex geologic structures, pre-stack depth migration does not yield results of sufficient quality for interpretation. We therefore propose a new wave-field imaging technique based on linearized inversion using the paraxial approximation of the wave equation. Using this technique we can remove the artifacts contaminating the individual depth images by integrating a priori information in the inverse problem. The application of the method to synthetic and real data shows that it allows us to largely improve the quality of the depth images at reasonable cost.We thus obtain an interpretable cube of depth images that makes migration velocity analysis feasible in complex structures. In 3D, due to the size of the problem there is still a large interest in using post stack techniques for velocity model determination. The quality of the results of such techniques relies on the quality of the stacking process. Classical data stacking techniques rely on simplifications that are not valid anymore in case of complex geologic structures. We propose a data stacking technique based on depth domain stacking after pre-stack depth migration, followed by explosive reflector modeling, to obtain the stacked seismic data. This method which is totally automatic yield 3 D stacked data that are suitable for 3D post stack velocity determination techniques.

  8. Acoustic Wave Dispersion and Scattering in Complex Marine Sediment Structures

    Science.gov (United States)

    2015-09-30

    Acoustic wave dispersion and scattering in complex marine sediment structures Charles W. Holland The Pennsylvania State University Applied...shear waves on dispersion in marine sediments . The first step will be development of the theory. WORK COMPLETED A brief summary of the work...propagation and scattering in the seabed. OBJECTIVES The objectives are to advance understanding of 1) the nature and mechanisms leading to sediment

  9. Structural Basis for TSC-1 TSC-2 Complex Formation

    Science.gov (United States)

    2008-03-01

    organs, including brain, skin, kidney, heart, and liver (1-2). This syndrome often manifests in early age with infantile seizures and patients may have...tuberin: working together for tumour suppression. Int. J. Cancer 118: 1-5 2. Astrinidis A, Henske EP. (2005). Tuberous sclerosis complex: linking growth...be regulated by changes in pH. Importantly, the BARD1 BRCT structure provides insights into the mechanisms by which the cancer - associated missense

  10. Generating a 2D Representation of a Complex Data Structure

    Science.gov (United States)

    James, Mark

    2006-01-01

    A computer program, designed to assist in the development and debugging of other software, generates a two-dimensional (2D) representation of a possibly complex n-dimensional (where n is an integer >2) data structure or abstract rank-n object in that other software. The nature of the 2D representation is such that it can be displayed on a non-graphical output device and distributed by non-graphical means.

  11. Characterization of a crosslinked nucleic acid - helix destabilizing protein complex

    Energy Technology Data Exchange (ETDEWEB)

    Karpel, R.L.; Levin, V.Y.; Haley, B.E.

    1986-05-01

    They have enzymatically synthesized /sup 3/H- and /sup 32/P-poly(A,8N/sub 3/A) from 8-N/sub 3/ADP and radiolabeled ADP, and have used this polynucleotide to photoaffinity label T4 gene 32 protein, as well as several other helix-destabilizing proteins (HDPs). Irradiation of /sup 32/P-/sup 3/H-poly(A,N/sub 3/A) mixtures for short durations produces a covalent complex, seen as a high molecular weight, radioactive band on SDS-polyacrylamide gels. Preliminary experiments on other HDPs, from prokaryotic, eukaryotic and animal viral sources, show analogous results. Several successful control experiments indicate that this system is suitable for binding site localization on /sup 32/P. Single-stranded nucleic acids competitively inhibit photolabeling. The effect of NaCl on photolabeling parallels the salt-dependence of /sup 32/P-poly(A,N/sub 3/A) binding. Photolabeling reaches a plateau after approx.1 min, and the formation of the high molecular weight complex parallels the reduction of free /sup 32/P on SDS gels. Staph. nuclease digestion of crosslinked complexes produces a diffuse, radioactive band on SDS gels, migrating just behind free /sup 32/P. When these digested complexes are subjected to reverse-phase HPLC on a C3 Ultrapore column, the nucleic acid /sup 32/P-label is seen to coelute with protein. They are currently employing RP-HPLC methods to locate the label on tryptic peptides of nuclease-digested complexes.

  12. Structural characterization of Heusler compounds using NMR

    Energy Technology Data Exchange (ETDEWEB)

    Wurmehl, Sabine; Fecher, Gerhard; Balke, Benjamin; Ksenofontov, Vadim; Jung, Verena; Felser, Claudia [Johannes Gutenberg - Universitaet, 55099 Mainz (Germany); Wojcik, Marek [Institute of Physics, Polish Academy of Sciences, 02-668 Warszawa (Poland)

    2007-07-01

    The L2{sub 1} ordered Heusler alloys Co{sub 2}Mn{sub 1-x}Fe{sub x}Si with 0{<=}x{<=}1 attracted much scientific interest, as they are predicted to show high spin polarisation at the Fermi-energy. Therefore Co{sub 2}Mn{sub 1-x}Fe{sub x}Si samples were investigated using spin echo nuclear magnetic resonance (NMR) measurements. This method provides a tool to measure the hyperfine fields. The hyperfine fields represent a very sensitive local probe to order-disorder phenomena. The NMR measurements of polycrystalline Co{sub 2}FeSi samples exhibit a two-peak spectrum with an additional shoulder. This additional signals are attributed to second-order quadrupole splitting, a so called asymmetric line broadening and might be caused by tension within the structure (strain). This effect occurs even in highly ordered systems. Thus previous structural results are corroborated, demonstrating even locally a very high degree of order in Co{sub 2}FeSi. The NMR spectra of the series Co{sub 2}Mn{sub 1-x}Fe{sub x}Si (0.1{<=}x{<=}0.9) exhibit multiplet structures. These might be explained by quadrupole splitting and statistical distribution of Mn and Fe atoms on the Mn site. In summary, the high degree of order in Co{sub 2}Mn{sub 1-x}Fe{sub x}Si is shown.

  13. 18-crown-6-sodium cholate complex: thermochemistry, structure, and stability.

    Science.gov (United States)

    Mihelj, Tea; Tomašić, Vlasta; Biliškov, Nikola

    2014-06-03

    18-Crown-6, one of the most relevant crown ethers, and sodium cholate, a steroidal surfactant classified as a natural bile salt, are components of a novel, synthesized coordination complex: 18-crown-6-sodium cholate (18C6·NaCh). Like crown ethers, bile salts act as building blocks in supramolecular chemistry to design new functionalized materials with a desired structure and properties. In order to obtain thermal behavior of this 1:1 coordination complex, thermogravimetry and differential thermal analysis were used, as well as microscopic observations and differential scanning calorimetry. Temperature dependent infrared (IR) spectroscopy gave a detailed view into phase transitions. The structures during thermal treatment were observed with powder X-ray diffraction, and molecular models of the phases were made. Hard, glassy, colorless compound 18C6·NaCh goes through crystalline-crystalline polymorphic phase transitions at higher temperatures. The room temperature phase is indexed to a triclinic lattice, while in the high temperature phases molecules take randomly one of the two different configurations in the unit cell, resulting in the 2-fold symmetry. The formation of cholesteric liquid crystalline phase occurs simultaneously with partial decomposition, followed by the isotropization with simultaneous and complete decomposition at much higher temperature, as obtained by IR. The results provide valuable information about the relationship between molecular structure, thermal properties, and stability of the complex, indicating the importance of an appropriate choice of cation, amphiphilic, and crown ether unit in order to synthesize compounds with desired behavior.

  14. X-ray diffraction characterization of suspended structures forMEMS applications

    Energy Technology Data Exchange (ETDEWEB)

    Goudeau, P.; Tamura, N.; Lavelle, B.; Rigo, S.; Masri, T.; Bosseboeuf, A.; Sarnet, T.; Petit, J.-A.; Desmarres, J.-M.

    2005-09-15

    Mechanical stress control is becoming one of the major challenges for the future of micro and nanotechnologies. Micro scanning X-ray diffraction is one of the promising techniques that allows stress characterization in such complex structures at sub micron scales. Two types of MEMS structure have been studied: a bilayer cantilever composed of a gold film deposited on poly-silicon and a boron doped silicon bridge. X-ray diffraction results are discussed in view of numerical simulation experiments.

  15. Characterization of Polyimide Foams for Ultra-Lightweight Space Structures

    Science.gov (United States)

    Meador, Michael (Technical Monitor); Hillman, Keithan; Veazie, David R.

    2003-01-01

    Ultra-lightweight materials have played a significant role in nearly every area of human activity ranging from magnetic tapes and artificial organs to atmospheric balloons and space inflatables. The application range of ultra-lightweight materials in past decades has expanded dramatically due to their unsurpassed efficiency in terms of low weight and high compliance properties. A new generation of ultra-lightweight materials involving advanced polymeric materials, such as TEEK (TM) polyimide foams, is beginning to emerge to produce novel performance from ultra-lightweight systems for space applications. As a result, they require that special conditions be fulfilled to ensure adequate structural performance, shape retention, and thermal stability. It is therefore important and essential to develop methodologies for predicting the complex properties of ultra-lightweight foams. To support NASA programs such as the Reusable Launch Vehicle (RLV), Clark Atlanta University, along with SORDAL, Inc., has initiated projects for commercial process development of polyimide foams for the proposed cryogenic tank integrated structure (see figure 1). Fabrication and characterization of high temperature, advanced aerospace-grade polyimide foams and filled foam sandwich composites for specified lifetimes in NASA space applications, as well as quantifying the lifetime of components, are immensely attractive goals. In order to improve the development, durability, safety, and life cycle performance of ultra-lightweight polymeric foams, test methods for the properties are constant concerns in terms of timeliness, reliability, and cost. A major challenge is to identify the mechanisms of failures (i.e., core failure, interfacial debonding, and crack development) that are reflected in the measured properties. The long-term goal of the this research is to develop the tools and capabilities necessary to successfully engineer ultra-lightweight polymeric foams. The desire is to reduce density

  16. Catecholase activity of a mu-hydroxodicopper(II) macrocyclic complex: structures, intermediates and reaction mechanism.

    Science.gov (United States)

    Koval, Iryna A; Belle, Catherine; Selmeczi, Katalin; Philouze, Christian; Saint-Aman, Eric; Schuitema, Anna Maria; Gamez, Patrick; Pierre, Jean-Louis; Reedijk, Jan

    2005-11-01

    The monohydroxo-bridged dicopper(II) complex (1), its reduced dicopper(I) analogue (2) and the trans-mu-1,2-peroxo-dicopper(II) adduct (3) with the macrocyclic N-donor ligand [22]py4pz (9,22-bis(pyridin-2'-ylmethyl)-1,4,9,14,17,22,27,28,29,30- decaazapentacyclo -[22.2.1(14,7).1(11,14).1(17,20)]triacontane-5,7(28),11(29),12,18,20(30), 24(27),25-octaene), have been prepared and characterized, including a 3D structure of 1 and 2. These compounds represent models of the three states of the catechol oxidase active site: met, deoxy (reduced) and oxy. The dicopper(II) complex 1 catalyzes the oxidation of catechol model substrates in aerobic conditions, while in the absence of dioxygen a stoichiometric oxidation takes place, leading to the formation of quinone and the respective dicopper(I) complex. The catalytic reaction follows a Michaelis-Menten behavior. The dicopper(I) complex binds molecular dioxygen at low temperature, forming a trans-mu-1,2-peroxo-dicopper adduct, which was characterized by UV-Vis and resonance Raman spectroscopy and electrochemically. This peroxo complex stoichiometrically oxidizes a second molecule of catechol in the absence of dioxygen. A catalytic mechanism of catechol oxidation by 1 has been proposed, and its relevance to the mechanisms earlier proposed for the natural enzyme and other copper complexes is discussed.

  17. Synthesis, crystal structure and applications of palladium thiosalicylate complexes

    Directory of Open Access Journals (Sweden)

    S.B. Moosun

    2017-05-01

    Full Text Available Three palladium thiosalicylate complexes [Pd(tb(bipy]·3H2O (1, [Pd2(tb2(bipy2]·(dtdb2 (2 and [Pd2(tb2(phen2]·dtdb·H2O (3 (bipy = bipyridine; phen = phenanthroline were prepared from the reaction of PdCl2(CH3CN2 with dithiosalicylic acid (dtdb which underwent cleavage to form thiobenzoate anion (tb in DMF/MeOH. Square planar geometries of the complexes with a N2SO coordination type were proposed on the basis of single crystal X-ray structural study. The presence of trapped and uncoordinated dtdb was observed in complexes 2 and 3. Complexes 1–3 were evaluated as catalysts for Heck coupling reactions of methyl acrylate with iodobenzene, and showed moderate activities at a very low catalyst loading. Complex 1 was found to inhibit the growth of bacteria and scavenge free radicals efficiently.

  18. Structure, bonding, and catecholase mechanism of copper bispidine complexes.

    Science.gov (United States)

    Comba, Peter; Martin, Bodo; Muruganantham, Amsaveni; Straub, Johannes

    2012-09-03

    Oxygen activation by copper(I) complexes with tetra- or pentadentate mono- or dinucleating bispidine ligands is known to lead to unusually stable end-on-[{(bispidine)Cu}(2)(O(2))](2+) complexes (bispidines are methyl-2,4-bis(2-pyridin-yl)-3,7-diazabicyclo-[3.3.1]-nonane-9-diol-1,5-dicarboxylates); catecholase activity of these dinuclear Cu(II/I) systems has been demonstrated experimentally, and the mechanism has been thoroughly analyzed. The present density functional theory (DFT) based study provides an analysis of the electronic structure and catalytic activity of [{(bispidine)Cu}(2)(O(2))](2+). As a result of the unique square pyramidal coordination geometry, the d(x(2)-y(2)) ground state leads to an unusual σ/π bonding pattern, responsible for the stability of the peroxo complex and the observed catecholase activity with a unique mechanistic pathway. The oxidation of catechol to ortho-quinone (one molecule per catalytic cycle and concomitant formation of one equivalent of H(2)O(2)) is shown to occur via an associative, stepwise pathway. The unusual stability of the end-on-peroxo-dicopper(II) complex and isomerization to copper(II) complexes with chelating catecholate ligands, which inhibit the catalytic cycle, are shown to be responsible for an only moderate catalytic activity.

  19. Physicochemical characterization of functionalized-nanostructured-titania as a carrier of copper complexes for cancer treatment

    Energy Technology Data Exchange (ETDEWEB)

    López, Tessy [Nanotechnology and Nanomedicine Laboratory, Metropolitan Autonomous University-Xochimilco, Calzada del Hueso 1100, Villa Quietud, Coyoacán, 04960 México D.F. (Mexico); Nanotechnology Laboratory, National Institute of Neurology and Neurosurgery “MVS”, Avenida Insurgentes Sur 3877, La Fama, Tlalpan, 14269 México D.F. (Mexico); Department of Chemical and Biomolecular Engineering, Tulane University, 6823 St. Charles Avenue, New Orleans (United States); Ortiz, Emma, E-mail: emma170@hotmail.com [Nanotechnology Laboratory, National Institute of Neurology and Neurosurgery “MVS”, Avenida Insurgentes Sur 3877, La Fama, Tlalpan, 14269 México D.F. (Mexico); Guevara, Patricia [Neuroimmunology Laboratory, National Institute of Neurology and Neurosurgery “MVS”, Insurgentes Sur 3877, La Fama, Tlalpan, 14269 México D.F. (Mexico); Gómez, Esteban [Nanotechnology Laboratory, National Institute of Neurology and Neurosurgery “MVS”, Avenida Insurgentes Sur 3877, La Fama, Tlalpan, 14269 México D.F. (Mexico); Novaro, Octavio [Institute of Physics-UNAM, Circuito de la Investigación Científica Ciudad Universitaria, CP 04510 México D.F. (Mexico)

    2014-07-01

    In the present paper we report the preparation and characterization of functionalized-TiO{sub 2} (F-TiO{sub 2}) to obtain a biocompatible material to be used as carrier of alternative anticancer agents: copper acetate and copper acetylacetonate. The sol–gel procedure was used to prepare the fuctionalized titania material through hydrolysis and condensation of the titanium's butoxide. Sulfate, amine and phosphate ions served as functional groups which were anchored to the titania's surface. Mineral acids and gamma amine butyric acid were the precursors and they were added at the initial step of the synthesis. The copper complexes were loaded on titania and were also added to the reactor synthesis from the beginning. Infrared and ultraviolet–visible spectroscopies were the principal techniques used to the characterization of F-TiO{sub 2} and copper complexes loaded on titania materials. Transmission Electronic Microscopy (TEM) was used to complement the characterization's studies. The biocompatibility of F-TiO{sub 2} was evaluated by treating different cancer cell lines with increased concentration of this compound. The amine, the sulfate and the phosphate on the titania's surface, as well as the integral structures of the metal complexes on titania were well identified by infrared and ultraviolet–visible spectroscopies. The TEM photographs of Cu(acac){sub 2}/F-TiO{sub 2} and Cu(Oac){sub 2}/F-TiO{sub 2} materials showed the formation of nanoparticles, which have sizes ranging from 4 to 10 nm, with no morphology alterations in comparison with F-TiO{sub 2} nanoparticles, suggesting that the presence of low quantities of copper do not affect the structure of the nanoparticles. The Energy Dispersive Spectroscopy (EDS) confirms the presence of copper on the titania's nanoparticles. The biological results indicate that there is more than 90% cell survival, thus suggesting that F-TiO{sub 2} does not cause damage to the cells. Therefore

  20. Structural Analysis of Protein Complexes by Cryo Electron Microscopy.

    Science.gov (United States)

    Costa, Tiago R D; Ignatiou, Athanasios; Orlova, Elena V

    2017-01-01

    Structural studies of biocomplexes using single-particle cryo-electron microscopy (cryo-EM) is now a well-established technique in structural biology and has become competitive with X-ray crystallography. The latest advances in EM enable us to determine structures of protein complexes at 3-5 Å resolution for an extremely broad range of sizes from ~200 kDa up to hundreds of megadaltons (Bartesaghi et al., Science 348(6239):1147-1151, 2051; Bai et al., Nature 525(7568):212-217, 2015; Vinothkumar et al., Nature 515(7525):80-84, 2014; Grigorieff and Harrison, Curr Opin Struct Biol 21(2):265-273, 2011). The majority of biocomplexes comprise a number of different components and are not amenable to crystallisation. Secretion systems are typical examples of such multi-protein complexes, and structural studies of them are extremely challenging. The only feasible approach to revealing their spatial organisation and functional modification is cryo-EM. The development of systems for digital registration of images and algorithms for the fast and efficient processing of recorded images and subsequent analysis facilitated the determination of structures at near-atomic resolution. In this review we will describe sample preparation for cryo-EM, how data are collected by new detectors, and the logistics of image analysis through the basic steps required for reconstructions of both small and large biological complexes and their refinement to nearly atomic resolution. The processing workflow is illustrated using examples of EM analysis of a Type IV Secretion System.

  1. Bio-inspired Fabrication of Complex Hierarchical Structure in Silicon.

    Science.gov (United States)

    Gao, Yang; Peng, Zhengchun; Shi, Tielin; Tan, Xianhua; Zhang, Deqin; Huang, Qiang; Zou, Chuanping; Liao, Guanglan

    2015-08-01

    In this paper, we developed a top-down method to fabricate complex three dimensional silicon structure, which was inspired by the hierarchical micro/nanostructure of the Morpho butterfly scales. The fabrication procedure includes photolithography, metal masking, and both dry and wet etching techniques. First, microscale photoresist grating pattern was formed on the silicon (111) wafer. Trenches with controllable rippled structures on the sidewalls were etched by inductively coupled plasma reactive ion etching Bosch process. Then, Cr film was angled deposited on the bottom of the ripples by electron beam evaporation, followed by anisotropic wet etching of the silicon. The simple fabrication method results in large scale hierarchical structure on a silicon wafer. The fabricated Si structure has multiple layers with uniform thickness of hundreds nanometers. We conducted both light reflection and heat transfer experiments on this structure. They exhibited excellent antireflection performance for polarized ultraviolet, visible and near infrared wavelengths. And the heat flux of the structure was significantly enhanced. As such, we believe that these bio-inspired hierarchical silicon structure will have promising applications in photovoltaics, sensor technology and photonic crystal devices.

  2. Radiological Characterization of TFA metallic tubes from CERN Accelerator Complex

    CERN Document Server

    Saraiva, João Pedro de Carvalho; Carvalho, João

    The scope of this thesis consists in the radiological characterization of chilled water pipes used for air-conditioning and exposed to ionizing radiation in the PS accelerator, one of the CERN accelerators, for more than 40 years. Due to corrosion problems, the 1200 m of steel pipeline were removed from the PS tunnel during the long shutdowns between the years 2000 to 2004. The radiological characterization, that included the use of FLUKA Monte Carlo simulations and the JEREMY code, began in mid-2011 and revealed a radionuclide inventory with the presence of 55Fe as dominant radionuclide and 60Co as dominant gamma emitter. Due to operational reasons, only 5.5% of the pipeline were characterized for validation. In the course of this work it was found that the contribution of both aforementioned radionuclides corresponds to more than 90% of the total computed IRAS factor (Indice Radiologique d’Acceptation en Stokage). Two different methods were used for the characterization of the PS pipes, yielding two diffe...

  3. Synthesis and Characterization of Metal Complexes with Schiff Base Ligands

    Science.gov (United States)

    Wilkinson, Shane M.; Sheedy, Timothy M.; New, Elizabeth J.

    2016-01-01

    In order for undergraduate laboratory experiments to reflect modern research practice, it is essential that they include a range of elements, and that synthetic tasks are accompanied by characterization and analysis. This intermediate general chemistry laboratory exercise runs over 2 weeks, and involves the preparation of a Schiff base ligand and…

  4. Crystal structure of phosphoethanolamine methyltransferase from Plasmodium falciparum in complex with amodiaquine

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Soon Goo; Alpert, Tara D.; Jez, Joseph M. (WU)

    2012-07-17

    Phosphoethanolamine N-methyltransferase (PMT) is essential for phospholipid biogenesis in the malarial parasite Plasmodium falciparum. PfPMT catalyzes the triple methylation of phosphoethanolamine to produce phosphocholine, which is then used for phosphatidylcholine synthesis. Here we describe the 2.0 {angstrom} resolution X-ray crystal structure of PfPMT in complex with amodiaquine. To better characterize inhibition of PfPMT by amodiaquine, we determined the IC{sub 50} values of a series of aminoquinolines using a direct radiochemical assay. Both structural and functional analyses provide a possible approach for the development of new small molecule inhibitors of PfPMT.

  5. Synthesis, structure and reactivity of rare-earth metal complexes containing anionic phosphorus ligands.

    Science.gov (United States)

    Li, Tianshu; Kaercher, Sabrina; Roesky, Peter W

    2014-01-07

    A comprehensive review of structurally characterized rare-earth metal complexes containing anionic phosphorus ligands is presented. Since rare-earth elements form hard ions and phosphorus is considered as a soft ligand, the rare-earth metal phosphorus coordination is regarded as a less favorite combination. Three classes of phosphorus ligands, (1) the monoanionic organophosphide ligands (PR2(-)) bearing one negative charge on the phosphorus atom; (2) the dianionic phosphinidene (PR(2-)) and P(3-) ligands; and (3) the pure inorganic polyphosphide ligands (Pn(x-)), are included here. Particular attention has been paid to the synthesis, structure, and reactivity of the rare-earth metal phosphides.

  6. Continuous Dimensionality Characterization of Image Structures

    DEFF Research Database (Denmark)

    Felsberg, Michael; Kalkan, Sinan; Krüger, Norbert

    2009-01-01

    Intrinsic dimensionality is a concept introduced by statistics and later used in image processing to measure the dimensionality of a data set. In this paper, we introduce a continuous representation of the intrinsic dimension of an image patch in terms of its local spectrum or, equivalently, its...... is the representation of confidences as prior probabilities which can be used within a probabilistic framework. To show the potential of our continuous representation, we highlight applications in various contexts such as image structure classification, feature detection and localisation, visual scene statistics...... and optic flow evaluation....

  7. Structural Investigations of Complex Oxides using Synchrotron Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hans-Conrad zur Loye

    2007-03-24

    The work is a collaborative effort between Prof. Hanno zur Loye at the University of South Carolina and Dr. Tom Vogt at Brookhaven National Laboratory. The collaborative research focuses on the synthesis and the structural characterization of perovskites and perovskite related oxides and will target new oxide systems where we have demonstrated expertise in synthesis, yet lack the experimental capabilities to answer important structural issues. Synthetically, we will focus on two subgroups of perovskite structures, the double and triple perovskites, and the 2H-perovskite related oxides belonging to the A3n+3mA’nB3m+nO9m+6n family. In the first part of the proposal, our goal of synthesizing and structurally characterizing new ruthenium, iridium, rhodium and ruthenium containing double and triple perovskites, with the emphasis on exercising control over the oxidation state(s) of the metals, is described. These oxides will be of interest for their electronic and magnetic properties that will be investigated as well.

  8. Synthesis and characterization of some metal complexes of a Schiff ...

    African Journals Online (AJOL)

    Sadtler Research Laboratories Inc. 1966 Standard Spectra, #21078K. 34. Bellamy, L.J. The Infrared Spectra of Complex Molecules, Vol. II, 2nd ed., Chapman and. Hall: New York; 1980. 35. Nakamoto, K. Infrared and Raman Spectra of Inorganic and Coordination Compounds, Part. B, 5th ed., John Wiley: New York; 1997.

  9. Synthesis and characterization of mixed ligand complexes of bio ...

    Indian Academy of Sciences (India)

    In these complexes, the nucleoside (uridine) acts as a monodentate ligand coordinating through O(4) under the conditions of investigation, whereas the amino acids coordinate through the carboxylate oxygen and the amino nitrogen. Distorted octahedral geometry for Cu(II) and octahedral geometries for both Ni(II) and ...

  10. Gold(I)-selenolate complexes: Synthesis, characterization and ...

    Indian Academy of Sciences (India)

    a recovery of enzyme activity is expected when the lig- and L attacks at the Au(I) centre to release the cata- lytically active selenol (scheme 4). Therefore, the li- gand exchange reactions at the Au(I) centres in protein– gold complexes may or may not affect the inhibition of enzymatic activity depending on the relative strength.

  11. synthesis, characterization an complexes with schiff base co ...

    African Journals Online (AJOL)

    userpc

    Aspergillus niger, Aspergillus flavus nd. Rhizoctoni abataicola cultured on potato dextrose agar as medium. The stock solution was prepared by dissolving .... Table 5:Antifungal activity of the Schiff base and its Ru(II) complexes. Compounds. Zone of Inhibition (mm). Aspergillus niger Aspergillus flavus Rhizoctonia bataicola.

  12. Synthesis, characterization and self-assembly of Co complexes ...

    Indian Academy of Sciences (India)

    (H-bonded) assemblies and afford inclusion complexes with solvents serving as the guest molecules.12 Self- assembly of phenolic compounds show that the ...... Board (SERB), Govt. of India for the generous financial support and CIF-USIC of this university for the instru- mental facilities. AA and DB thank University Grant.

  13. Synthesis and characterization of mixed ligand complexes of bio ...

    Indian Academy of Sciences (India)

    Unknown

    bio-metals with pyrimidine nucleoside (uridine) and amino acids. P RABINDRA REDDY* and A MOHAN REDDY. Department of Chemistry, Osmania University, Hyderabad 500 007, India. MS received 24 December 1999; revised 28 August 2000. Abstract. The mixed ligand complexes of Cu(II), Ni(II) and Co(II) with uridine ...

  14. Using complex networks to characterize international business cycles.

    Directory of Open Access Journals (Sweden)

    Petre Caraiani

    Full Text Available BACKGROUND: There is a rapidly expanding literature on the application of complex networks in economics that focused mostly on stock markets. In this paper, we discuss an application of complex networks to study international business cycles. METHODOLOGY/PRINCIPAL FINDINGS: We construct complex networks based on GDP data from two data sets on G7 and OECD economies. Besides the well-known correlation-based networks, we also use a specific tool for presenting causality in economics, the Granger causality. We consider different filtering methods to derive the stationary component of the GDP series for each of the countries in the samples. The networks were found to be sensitive to the detrending method. While the correlation networks provide information on comovement between the national economies, the Granger causality networks can better predict fluctuations in countries' GDP. By using them, we can obtain directed networks allows us to determine the relative influence of different countries on the global economy network. The US appears as the key player for both the G7 and OECD samples. CONCLUSION: The use of complex networks is valuable for understanding the business cycle comovements at an international level.

  15. Metathesis synthesis and characterization of complex metal fluoride ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Metathesis synthesis of complex metal fluorides using mechanochemical activation has been reported. The high lattice energy of the byproduct KCl helps the reaction towards product formation in under 20 min. The proposed process, in contrast to the available methods of synthesis, is very rapid, economical and ...

  16. Using complex networks to characterize international business cycles.

    Science.gov (United States)

    Caraiani, Petre

    2013-01-01

    There is a rapidly expanding literature on the application of complex networks in economics that focused mostly on stock markets. In this paper, we discuss an application of complex networks to study international business cycles. We construct complex networks based on GDP data from two data sets on G7 and OECD economies. Besides the well-known correlation-based networks, we also use a specific tool for presenting causality in economics, the Granger causality. We consider different filtering methods to derive the stationary component of the GDP series for each of the countries in the samples. The networks were found to be sensitive to the detrending method. While the correlation networks provide information on comovement between the national economies, the Granger causality networks can better predict fluctuations in countries' GDP. By using them, we can obtain directed networks allows us to determine the relative influence of different countries on the global economy network. The US appears as the key player for both the G7 and OECD samples. The use of complex networks is valuable for understanding the business cycle comovements at an international level.

  17. Ultrathin conformal coating for complex magneto-photonic structures

    Science.gov (United States)

    Pascu, Oana; Caicedo, José Manuel; López-García, Martín; Canalejas, Víctor; Blanco, Álvaro; López, Cefe; Arbiol, Jordi; Fontcuberta, Josep; Roig, Anna; Herranz, Gervasi

    2011-11-01

    We report on an extremely fast and versatile synthetic approach, based on microwave assisted sol-gel chemistry, that allows a conformal nanometric coating of intricate three-dimensional structures. Using this methodology, we have achieved a conformal coverage of large areas of three-dimensional opals with a superparamagnetic manganese ferrite layer, yielding magneto-photonic crystals with excellent quality. The use of a ternary oxide for the ultrathin coating demonstrates the potential of this methodology to realize three-dimensional structures with complex materials that may find applications beyond photonics, such as energy, sensing or catalysis.We report on an extremely fast and versatile synthetic approach, based on microwave assisted sol-gel chemistry, that allows a conformal nanometric coating of intricate three-dimensional structures. Using this methodology, we have achieved a conformal coverage of large areas of three-dimensional opals with a superparamagnetic manganese ferrite layer, yielding magneto-photonic crystals with excellent quality. The use of a ternary oxide for the ultrathin coating demonstrates the potential of this methodology to realize three-dimensional structures with complex materials that may find applications beyond photonics, such as energy, sensing or catalysis. Electronic supplementary information (ESI) available. See DOI: 10.1039/c1nr10959f

  18. Metal complexes as antibacterial agents: Synthesis, characterization and antibacterial activity of some 3d metal complexes of sulphadimidine

    OpenAIRE

    Adedibu Clement Tella; Joshua Ayoola Obaleye

    2010-01-01

    Metal complexes of Sulphadimidine(SAD) were synthesized.The complexes were formulated as [Co(SAD)2Cl2], [Cu(SAD)2 (H2O)2], [Ni (SAD)2 Cl2 H2O], [Cd (SAD)2 Br2], [Fe (SAD)3](H­2O)­3 and [Mn (SAD)2Cl2] characterized by elemental Analysis, conductivity, IR , UV-Vis, Magnet moment and 1H-NMR and Mass spectroscopies. Co(II), Mn (II),  and Ni(II) sulphadimidine complexes consist of metal ion which coordinates through amino nitrogen of the terminal NH2 group and oxygen of sulfonamidic g...

  19. Random field Ising model and community structure in complex networks

    Science.gov (United States)

    Son, S.-W.; Jeong, H.; Noh, J. D.

    2006-04-01

    We propose a method to determine the community structure of a complex network. In this method the ground state problem of a ferromagnetic random field Ising model is considered on the network with the magnetic field Bs = +∞, Bt = -∞, and Bi≠s,t=0 for a node pair s and t. The ground state problem is equivalent to the so-called maximum flow problem, which can be solved exactly numerically with the help of a combinatorial optimization algorithm. The community structure is then identified from the ground state Ising spin domains for all pairs of s and t. Our method provides a criterion for the existence of the community structure, and is applicable equally well to unweighted and weighted networks. We demonstrate the performance of the method by applying it to the Barabási-Albert network, Zachary karate club network, the scientific collaboration network, and the stock price correlation network. (Ising, Potts, etc.)

  20. The interplay between microscopic and mesoscopic structures in complex networks.

    Directory of Open Access Journals (Sweden)

    Jörg Reichardt

    Full Text Available Understanding a complex network's structure holds the key to understanding its function. The physics community has contributed a multitude of methods and analyses to this cross-disciplinary endeavor. Structural features exist on both the microscopic level, resulting from differences between single node properties, and the mesoscopic level resulting from properties shared by groups of nodes. Disentangling the determinants of network structure on these different scales has remained a major, and so far unsolved, challenge. Here we show how multiscale generative probabilistic exponential random graph models combined with efficient, distributive message-passing inference techniques can be used to achieve this separation of scales, leading to improved detection accuracy of latent classes as demonstrated on benchmark problems. It sheds new light on the statistical significance of motif-distributions in neural networks and improves the link-prediction accuracy as exemplified for gene-disease associations in the highly consequential Online Mendelian Inheritance in Man database.